method of laser hardening a surface of a workpiece; method of laser hardening the surfaces of trunni

专利摘要:
METHOD OF LASER HARDENING OF A SURFACE OF A WORKPIECE; METHOD OF LASER HARDENING OF CRANKSHAFT TRUCK SURFACES; METHOD FOR HARDENING SURFACE AREAS OF AT LEAST TWO CRANKSHAFT; APPLIANCE FOR HARDENING A SURFACE AREA OF A WORKPIECE; APPARATUS FOR LASER HARDENING OF CRANKSHAFT TRUCK SURFACES; AND APPARATUS FOR SIMULTANEOUS LASER HARDENING OF CRANKSHAFT TRUCK SURFACES. This is a method of laser hardening a surface area of a workpiece, such as a crankshaft trunnion surface, which comprises: generating relative motion between the workpiece surface and a laser source to allow a laser spot to be subsequently projected onto different portions of said surface area and, during said relative movement, to repetitively sweep the laser beam (2) for the purpose of producing an effective two-dimensional equivalent laser spot (5) on said surface area. The scan pattern can comprise at least three substantially parallel lines, which the laser spot follows in a certain order. When the workpiece comprises several journals that (...).
公开号:BR112016020870B1
申请号:R112016020870-6
申请日:2015-02-11
公开日:2021-05-18
发明作者:Jesús Domínguez；Paula SANCHO；Olatz BILBAO
申请人:Etxe-Tar, S.A.；
IPC主号:

专利说明:

FIELD OF TECHNIQUE
[001] The present invention relates to the field of surface hardening of ferrous material products such as steel, for example, crankshafts, through laser. TECHNICAL STATUS
[002] It is well known in the art to harden ferrous materials, such as medium carbon steel, by heating the material to a high temperature below its melting temperature and its subsequent sudden cooling, i.e., cooling sufficiently quickly to form hardened martensite. Heating can take place in furnaces or through induction heating, and cooling can take place through the application of a coolant such as water or water mixed with other components.
[003] Often, it is only the surface that needs to be hardened. Surface hardening increases the wear resistance of the material and can sometimes also be used to increase the fatigue strength caused by residual compressive stresses. Surface hardening can be useful for hardening surfaces that will be subject to wear when in use, for example bearing surfaces such as crankshaft journal surfaces.
[004] Laser surface hardening is a method of surface treatment in which high energy laser light is employed as a heat source to harden the surface of a substrate. It is known to use laser light to achieve surface hardening, see for example: - F. Vollertsen, et al., "State of the art of Laser Hardening and Cladding", Proceedings of the Third International WLT-Conference on Lasers in Manufacturing 2005 Munich, June 2005; - M. Seifert, et al. , "High Power Diode Laser Beam Scanning in Multi-Kilowatt Range", Proceedings of the 23rd International Congress on Applications of Lasers and Electro-Optics 2004; - S. Safdar, et al. , "An Analysis of the Effect of Laser Beam Geometry on Laser Transformation Hardening", Journal of Manufacturing Science and Engineering, August 2006, volume 128, pages 659-667; - H. Hagino, et al. , "Design of a computer-generated hologram for achieving a uniform hardened profile by laser hardening with a high-power laser diode", Precision Engineering 34 (2010), pages 446-452; - document US-4313771-A; - document DE-4123577-A1; - document EP-1308525-A2; - document EP-2309126-A1; - document JP-2008-202438-A; - document JP-S61-58950-A; - document US-4797532-A.
[005] The use of laser light for surface hardening involves several advantages: the laser beam is essentially independent of the workpiece, is easily controlled, does not require a vacuum and does not generate combustion products. Furthermore, since the laser beam usually only heats the metal product or workpiece locally, the rest of the workpiece can act as a heat sink, ensuring rapid cooling, which is also known as sudden self-cooling : The interior cold of the workpiece constitutes a heat sink large enough to abruptly cool the hot surface by conducting heat inward at a rate high enough to allow martensite to form on the surface. In this way, the need for external cooling means such as coolant fluids can be eliminated.
[006] A problem involved with using laser light as the heat source in metal hardening processes is that the width of the hardening zone is limited by the dimensions of the laser spot. It is known to use optical elements to modify the shape of the dot, for example, to provide a substantially rectangular dot that has a more or less uniform intensity distribution. As an alternative, scanning means (such as a scanning mirror associated with conduction means) can be used to repetitively move the point on the trajectory, so that the heat source can be considered a rectangular source moving along the path. trajectory.
[007] Despite its advantages, laser hardening is not used very often as it is believed that the production rate will not be high enough for many practical applications of this technique and due to the fact that it is difficult to make all the parts that should to be heated are heated to the desired point. Heating is essential to ensure that hardening and tempering is achieved, to the required depths, but without causing damage from overheating.
[008] For example, a crankshaft (the part of the engine that transforms linear reciprocating piston movement into rotation) is a complex product that has often been designed as difficult to harden by laser light. An example of a crankshaft is shown in Figure 1. The 1000 crankshaft is a forged or cast steel product that has two or more centrally located coaxial cylindrical journals 1001 (also known as "main journals") and one or more pin journals offset cylindrical crankshafts 1002 (also known as "rod journals"), separated by counterweights and mats that establish walls 1005 that extend substantially perpendicular to the journal surfaces. The complex shape of the product can make it difficult to properly "sweep" the surface with the laser beam; the paths or areas for hardening can have different widths and/or be asymmetric and/or be arranged in different planes (which is the case with walls 1005 and the surfaces of trunnions 1001 and 1002). Thus, today, high-frequency induction heating followed by a polymer-based water quenching process is often used for hardening crankshafts. However, this process, while proven to be helpful in achieving the desired hardening, does involve certain disadvantages. For example, inductors for creating induction heating need to be designed according to the specific crankshaft design, which reduces flexibility: adapting an induction machine to a new type of crankshaft can be time-consuming and costly. Additionally, induction heating is expensive in terms of the energy required to heat the crankshaft to the desired point. Furthermore, the cooling process is complex, costly and challenging from an environmental point of view, due to the use of large amounts of coolant that are required. Furthermore, parameters such as temperature and coolant flow need to be carefully controlled to ensure a correct hardening process.
[009] Thus, hardening with the use of laser light as the heat source can be an attractive alternative in terms of flexibility, ecology, energy consumption and costs.
[010] DE-10 2005 005 141-B3 discloses a method for laser hardening the journal surfaces of a crankshaft. According to this method, a six-axis industrial robot is used to hold the crankshaft and to subsequently rotate it around the geometric axis of the main journals and around the geometric axes of the connecting rod journals, while heating the respective journals. with laser light. In this way, through the use of the industrial robot's motion capabilities, the distance between the laser source and the surface on which the laser beam is projected can be kept constant.
[011] Also, the document US-2004/0244529-A1 teaches the use of laser to harden a small region of a crankshaft. In that case, laser light is used to harden a plurality of spaced apart portions, the extent of the portions varying over the region to be hardened. As only a smaller portion of the crankshaft is hardened with these spaced portions, there is no need to worry about overheating other portions that are more sensitive to heat.
[012] The document DE-3905551-A1 teaches a system for hardening a surface of a crankshaft, in which a laser beam is projected onto a crankshaft and in which there is a relative movement between the beam and the crankshaft so that the beam will subsequently be projected onto different portions of the crankshaft. The power or power distribution in the beam is adapted depending on the geometry of the respective portion of the crankshaft and depending on the desired penetration depth of the laser beam. One problem with the approach taught by DE-3905551-A1 is that it may not allow for a high production rate. To achieve a sufficient hardened layer depth (in the engine industry, typically, hardening depths of at least 800, 1000, 1500, 2000 or even 3000 µm are required in terms of effective layer depth, and is often desired having 100 % martensite transformed to depths of 200 μm or more) , it is not enough to raise the temperature of a certain portion of the surface, but the energy needs to be applied for a long enough time to heat not only the surface but also the material beneath. the surface, to a sufficient depth. Since excessive surface heating is not desired, to achieve the desired penetration, the best solution is not simply to increase the amount of laser beam power, but rather the time during which the laser heating is applied to the relevant area. In the system disclosed in DE-3905551-A1 where the laser beam is held stationary and applied to a specific area, obtaining adequate heating and penetration into the main portions of the main journals or connecting rod journals appears to require substantial amounts of time. Thus, DE-3905551-A1 can describe a suitable method for hardening very specific portions of the surface of a crankshaft, but not for hardening the general surfaces of the journals.
[013] Furthermore, the document EP-1972694-A2 focuses on the hardening of specific portions of a crankshaft, namely, the fillet portions, with the use of one or more lasers. Laser light is directed onto the portion to be hardened and the crankshaft is rotated. The disclosed method may include a pre-heating step, a main heating step, and a post-heating step. It appears that the laser irradiation is kept constant while the crankshaft rotation takes place. EP-1972694-A2 does not stress the risk of overheating more heat sensitive portions of the crankshaft surface.
[014] The document US-2004/0108306-A1 states that the automobile industry uses the induction heating process to harden the bearings of a crankshaft, that is, the surfaces of the main journals and the connecting rod journals, as a process of Mechanical lamination is used to laminate the fillets to improve compressive stresses. However, according to US-2004/0108306-A1 , these processes are known to be costly, time-consuming, lead to non-uniformities and have a propensity for cracking in the oil lubrication holes that requires a quenching process. Document US-2004/0108306-A1 teaches a laser thread heat treatment which aims to eliminate the need for the mechanical lamination process. Closed-loop temperature control through the use of an optical pyrometer is proposed. The use of a controllable x,y mechanism to maintain a fixed heating distance between the laser and the thread is proposed.
[015] SM Shariff, et al., "Laser Surface Hardening of a Crankshaft", SAE 2009-28-0053 (SAE International), discusses laser surface hardening of a driven crankshaft at a hardened layer depth above 200 µm with a hardness of 500-600 HV at different places mentioned. The document mentions the problem of fusing at the periphery of holes due to the reduced heat sink effect and heat build-up at the edge. It is determined that the problem can be addressed by reducing the preheating effect at the edge of the hole by choosing an appropriate start location and by varying the process parameters within the allowable range.
[016] One reason why laser hardening has not become more often used in the context of complex products like crankshafts is that it is believed that it can be difficult to achieve correct heating of parts, ie sufficient heating to ensure hardening correct (in general, the hardened layer needs to have an effective layer depth of at least 800 μm or more, such as at least 1000, 1500, 2000 μm or more, and/or having 100% transformed martensite to a depth such as 200 μm or more), while preventing overheating of sensitive portions. For example, in the case of a crankshaft as in figure 1, it is necessary to be careful with heating the journals in correspondence with the oil lubrication holes 1003 and optionally also in relation to the fillets 1004. For example, if a laser spot large is simply projected onto the trunnion surface during trunnion rotation to heat the entire surface, if the rotational speed and power of the laser beam are kept constant so that each portion of the surface receives the same amount of energy and if if this energy is sufficient to achieve adequate heating of most of the surface to produce the desired hardening, the heating can become excessive at the edges of the oil lubrication holes, thereby damaging said edges. The same can happen with fillets, which are commonly undercut; therefore, there are edges that can be damaged if overheated. DESCRIPTION OF THE INVENTION
[017] A first aspect of the invention relates to a method of laser hardening a surface of a workpiece, wherein the workpiece comprises at least one surface area to be hardened, wherein the method comprises:
[018] project a laser beam from a laser source onto said surface area, with the purpose of producing a laser spot (that is, what can be called a real laser spot) in said area of surface;
[019] generate a relative movement between the surface of the workpiece and the laser source (for example, through the displacement of the workpiece and/or the laser source; such displacement may, in some embodiments of the invention, include, eg rotation of the workpiece), thereby enabling the laser spot to be subsequently projected onto different portions of said surface area;
[020] during said relative movement, repetitively sweeping the laser beam along the respective portion of said surface area in two dimensions, following a scanning pattern in order to produce an effective laser spot or two-dimensional equivalent in said area surface, wherein said effective laser spot has an energy distribution. This energy distribution will depend on parameters such as the power of the actual laser spot, the scan pattern, and the speed at which the laser spot is swept along different portions or segments of the scan pattern.
[021] Due to relative motion, said effective laser dot travels along said surface area, for example, in a first direction, as in the case of crankshaft journal hardening, in a circumferential direction of the crankshaft journal. crankshaft.
[022] This type of provision is disclosed in the international patent application PCT/EP2013/067949 of the same applicant, whose contents are incorporated in this document by way of reference. This arrangement is advantageous in that it allows, inter alia, the energy distribution along and through the effective laser spot to be dynamically adapted while the effective laser spot is traveling along the surface area to be hardened, through adaptation, by example, one or more of the parameters indicated above, such as the structure of the scan pattern (such as the number, orientation and/or length of scan pattern segments) and/or the speed at which the laser spot is shifted along the scan pattern, such as along different portions or segments of the scan pattern. For example, different speeds can be assigned to different segments, and the structure of the scan pattern and/or the speed assigned to one or more of the segments can be modified while the relative movement of the effective laser spot along the surface area being hardened is taking place. Thereby, the energy distribution can be adapted to consider certain sub-areas more sensitive to heat. A typical example of such a more heat sensitive sub-area is the area adjacent to an oil lubrication hole of a crankshaft journal.
[023] According to that aspect of the invention, the scan pattern comprises at least three segments and said laser beam scanning is performed such that said laser beam or actual laser spot follows at least one of said segments more often than follows at least one other of said segments. This arrangement is advantageous in that it enhances the flexibility and manner in which the sweep pattern can be used to provide adequate energy distribution and, where desired, symmetrical or substantially symmetrical. For example, one of said segments can be used as a trajectory or bridge followed by the laser dot when moving between two other segments, so that the transfer of the laser dot between different portions (such as an end and a beginning) of the pattern Scanning can be performed using segments (such as intermediate segments) of the scan pattern for transfer, whereby transfer can often be performed without turning off the laser beam and without distorting the symmetry of the energy distribution. two-dimensional, when such symmetry is desired.
[024] In some embodiments of the invention, the scan pattern comprises at least three substantially parallel curved or straight lines distributed one after the other in a first direction, wherein said lines generally extend in a second direction, wherein the said at least three lines comprise a first line, at least one intermediate line and a last line arranged one after the other in said first direction, wherein said laser beam scanning is performed so that said laser beam or point The actual laser beam follows said intermediate line more often than said laser beam follows said first line and/or said last line. That is, for example, the laser beam can, on average, follow said intermediate line twice as often as it follows said first line and said last line, for example, the laser beam can travel along said intermediate line each time it moves from the first line to the last line and vice versa. That is, the intermediate line(s) can serve as a type of bridge followed by the actual laser dot when moving between the first and the last line.
[025] It was concluded that this arrangement is practical and easy to implement, and it was concluded that the proper energy distributions can often be obtained by adapting the scan speed and without substantially adapting the power of the laser beam. It is also possible to modify the power of the laser beam during scanning for the purpose of shaping the power distribution, but fast switching power is not always possible or desirable, and having the laser beam at a low power level or turned off during substantial parts of the scan cycle may imply non-optimal use of laser capacity. Therefore, it is often desirable to operate the laser beam completely in the on state to take full advantage of the available power.
[026] It is often desirable to use three or more lines arranged in this way, that is, one after the other in a direction other than, as perpendicular to, the direction along which the lines extend, in order to achieve a substantial extension of the effective laser spot not only in the direction along the lines, but also in the other direction, in order to make the effective laser spot suitable for heating a sufficiently large surface portion to a high enough temperature and to maintain the temperature at the desired level or levels for sufficient time, while allowing the effective laser spot to travel with sufficient speed, thereby allowing for high productivity. Thus, a substantial extension of the effective laser spot in two dimensions is often an advantage.
[027] In some embodiments of the invention, the scanning pattern comprises at least three substantially parallel lines or segments, distributed one after the other in a first direction, as in the direction along which the effective laser spot travels during the process of hardening, wherein said lines extend in a second direction, such as in a direction perpendicular to the first direction. In some embodiments of the invention, said at least three lines comprise a first line, at least an intermediate line and a last line, arranged one after the other in said first direction, and the laser beam scanning is carried out so that the laser point is scanned along said lines according to a sequence according to which the laser point, after following said first line, follows said intermediate line, said last line, said intermediate line and said first line, in that order.
[028] The above definition does not mean that the scan needs to start with the first line, but only indicates the sequence in which the laser spot travels or follows the lines mentioned above in the scan pattern. Also, this does not preclude that, between (as before or after) following some or all of the lines indicated above, the effective laser spot may follow other lines, such as lines that interconnect the first, last and middle line, and/or additional intermediate lines.
[029] That is, in these modes, after moving along the first line, the laser point always follows said intermediate line twice before moving along the first line again. While a more immediate approach may have been used to perform the scan so that, after said last line, the laser spot returns directly to said first line, it was concluded that the sequence followed according to these embodiments of the invention is suitable for achieving a symmetrical energy distribution around a geometric axis of symmetry extending in said first direction.
[030] In some embodiments of the invention, the scan pattern comprises a plurality of said intermediate lines. The number of lines can be chosen by the operator, the process designer or the equipment designer depending, for example, on the size of the actual laser spot and the desired length of the effective laser spot, for example, in the first direction. For example, a minimum number of lines can be three lines, but in many practical implementations a larger number of lines can be used, such as four, five, six, ten or more lines, when counting the first, last, and the middle line. In some embodiments of the invention, the number of lines is modified to modify the energy distribution while the effective laser spot is traveling along the surface area to be hardened.
[031] In some embodiments of the invention, the laser spot is displaced with a higher speed along said at least one intermediate line than along said first line and last line. This is often preferred in order to achieve adequate energy distribution in said first direction, at least during a portion or a substantial portion of the hardening process. The higher speed of the laser dot when moving along intermediate lines, or at least when moving along one or some of them, compensates for the fact that the laser dot moves along said intermediate lines twice as often as it moves along the first and last lines. For example, the laser spot speed along intermediate lines may, in some embodiments of the invention, be about twice the laser spot speed along the first and/or last lines. Speed may be different for different intermediate lines. The speed for each line can be chosen according to a desired energy distribution in the first direction. Now, the speed with which the effective laser spot is moved along different lines or segments of the scan pattern can be dynamically modified, while the effective laser spot is traveling along the surface area to be hardened, for example , to adapt the power distribution in order to prevent overheating of sub-areas that are more sensitive to heat.
[032] In some embodiments of the invention, the scan pattern additionally comprises lines extending in said first direction, between the ends of the first line, the last line and the intermediate line, whereby said laser spot follows said lines that extend in said first direction when moving between said first line, said intermediate lines and said last line. In some embodiments of the invention, the laser spot is moved at a higher speed along said lines extending in the first direction than along said first line and said last line, at least during part of the hardening process. .
[033] In some embodiments of the invention, the laser spot is moved along said scanning pattern without turning the laser beam on and off and/or while keeping the laser beam power substantially constant. This makes it possible to scan at a high speed without considering the laser's ability to switch between different power levels, such as on and off, and makes it possible to use laser equipment that may not allow very fast switching between power levels. Also, this provides efficient use of the available output power, ie the capacity of the laser equipment in terms of power.
[034] In some embodiments of the invention, the work piece is a crankshaft.
[035] Another aspect of the invention relates to a method of laser hardening trunnion surfaces of a crankshaft, wherein said crankshaft has at least one first trunnion having a first width and at least one second trunnion having a second width, wherein said second width is greater than said first width, wherein each of said journals comprises a surface area to be hardened, wherein said surface area extends in a corresponding first direction. to a circumferential direction of the journal and in a second direction parallel to a geometric axis of rotation of the crankshaft. The method comprises: A) during at least one stage of the method, or stage of a crankshaft hardening process using said method, simultaneously projecting a laser beam from a first laser source and a laser beam from a second laser source over said surface area of said second trunnion; and B) during at least one further stage of the method or process, projecting a laser beam from said first laser source onto said surface area of said first trunnion, while simultaneously projecting a laser beam from said second laser source on another portion (such as another journal, such as another first journal) of a crankshaft, which can be the same or a different crankshaft.
[036] The use of two sources/beams of lasers, according to this second aspect of the invention, is beneficial as it allows an increase in efficiency in terms of using the laser power available during the hardening process. If only one laser is used, it is necessary to use a laser that has adequate power to allow it to provide an effective laser spot with an adequate energy distribution for hardening the surface of a crankshaft, and with a size that extends through most also of the journals that have the second width - that is, the wider journals to be hardened - while, on the other hand, it also extends sufficiently in the circumferential direction to allow a sufficiently high travel speed of the effective laser spot in said circumferential direction - due to the relative motion discussed above - while at the same time allowing the relevant parts of the trunnion to be heated for a sufficiently long time without unwanted excessive energy swings. Such lasers may be available, but the problem is that a laser that has this capacity and this power may not be used efficiently when it is used to harden the surfaces of the trunnions that have the first width, that is, the smallest width. That is, for example, in the case of a journal like the one in figure 1, a laser suitable for hardening, by itself, the surfaces of the connecting rod journals (which are about twice as wide as the main journals) in one way. efficient and at a speed that implies high productivity, it will be used in a non-ideal way when it is used to harden a main journal.
[037] Thus, the use of two laser sources, which can be adapted so that their capacity/power is sufficient so that each of them can be used for adequate and efficient hardening of the journals that have a first width (a smaller) with a desired speed in terms of finished trunnions per unit of time, and which can be used together to harden trunnions having the second (larger) width at a desired speed, allows more efficient use of available laser power . When the two-dimensional energy distribution of each effective laser spot is determined by scanning the laser spot along the scan pattern, the same can apply to scanning equipment: two smaller or simpler scan patterns can be combined to form the desired energy distribution, in a way that would require a larger or more complex scanning pattern if only a laser and associated scanning medium were used.
[038] In some embodiments of the invention, the method comprises: A) during at least one stage of the method, projecting a laser beam from a first laser source onto said surface area of said second trunnion, for the purpose of producing an effective laser spot on said surface area, wherein said effective laser spot extends, in said second direction, across a first portion of the surface area to be hardened, and projecting another laser beam to from a second laser source on said surface area of said second trunnion, for the purpose of producing an effective laser spot on said surface area, wherein said effective laser spot extends, in said second direction, along a second portion of the surface area to be hardened, wherein said first portion and said second portion together extend over most of said surface area to be hardened; B) during at least another stage of the method, projecting a laser beam from said first laser source onto said surface area of said first trunnion, in order to produce an effective laser spot on said surface area , wherein said effective laser spot extends, in said first direction, across most of the surface area to be hardened; during both said stages of the method, generating a relative movement between the surface of the crankshaft and the laser source in said circumferential direction, for the purpose of subsequently projecting the effective laser points onto different portions of said surface areas in the circumferential direction; wherein said effective laser points have a two-dimensional energy distribution.
[039] This two-dimensional energy distribution can be fixed or can be dynamically adapted, for example, to accommodate subareas more or less sensitive to heat. For example, the effective laser spot can be established by scanning an actual laser spot through the respective portion of said surface area in two dimensions, following a scanning pattern for the purpose of producing an effective laser spot or two-dimensional equivalent. on said surface area, wherein said effective laser spot having a two-dimensional energy distribution depends on parameters such as sweep speed (the speed with which the laser spot moves along different parts or segments of the laser pattern. scan), laser spot power and power variation across scan pattern, scan pattern structure, laser spot size, etc. One or more of these parameters can be dynamically adapted while the effective laser spot is traveling around the circumference of the respective trunnion, in order to adapt the energy distribution when, for example, the effective laser spot approaches a sensitive area to heat, such as the area adjacent to an oil lubrication hole. This concept and related concepts are disclosed in the international patent application PCT/EP2013/067949 of the same applicant, whose contents are incorporated in this document by way of reference.
[040] In some embodiments of the invention, the first portion is placed substantially adjacent to said second portion, without any substantial overlap between the two portions. For example, the overlap can be less than 5, 10, 2 0 or 3 0 %; it can be, in some modalities, zero or almost zero.
[041] In other embodiments of the invention, the first portion and the second portion are substantially superimposed on each other. For example, the overlap can be more than 70, 80, or 90%, such as 100%.
[042] That is, the first portion and the second portion can be separate non-overlapping portions, but they can also be superimposed on each other. In some embodiments of the invention, the first and second portions are substantially or completely overlapping in space. What is important is that the combined effect of the two laser beams produces a total two-dimensional energy distribution that is of sufficient extension in the first and second directions, and with sufficient energy density in terms of applied power per unit area, to allow that the trunnion is hardened effectively and with quality (eg without unwanted excessive energy oscillations within the effective laser spot) and with the effective laser spot traveling at a sufficient speed in the circumferential direction to achieve high productivity in terms of products per hour.
[043] In some embodiments of the invention, during at least one stage of the method, the laser beam from the first laser source is projected onto a trunnion of a crankshaft, and the laser beam from the second laser source is projected onto a trunnion of another crankshaft. In many cases, a crankshaft will have multiple journals that will not be optimal in terms of how effectively it uses the available laser power. For example, when two laser sources are used to harden the wider journals together, and to harden the shorter journals separately, when the number of shorter journals is not even, during a hardening sequence or step of trunnions, a laser source will remain idle.
[044] For example, in the case of a crankshaft like the one in figure 1, there are four wide connecting rod journals, but there may be five smaller main journals. The two laser sources can be used simultaneously to harden each of the connecting rod journals, and can be used separately to harden the different main journals so that two main journals can be hardened simultaneously. However, after the hardening of four of the main trunnions, the fifth will remain, and one of the laser sources is sufficient to harden the same. To enhance effectiveness, the other laser source, rather than sitting idle, can then be used to harden a second crankshaft main journal. This can serve to further enhance the effectiveness of using the equipment.
[045] In some embodiments of the invention, during at least one stage of the process, two journals having the first width are hardened in one step, and a journal having the second width is hardened in another step, in which said two steps follow one after the other, and without any relative movement between the laser sources and the crankshaft, in the second direction, between said two steps. This can speed up the process as it can reduce the time between the two steps.
[046] In some embodiments of the invention, said surface area comprises at least one sub-area more sensitive to heat and at least one sub-area less sensitive to heat, wherein said energy distribution is adapted so that it is different in a sub-area more heat sensitive, such as the area adjacent to an oil lubrication hole of a crankshaft, than in a less heat sensitive sub-area, in order to prevent overheating of said more heat-sensitive sub-area.
[047] A further aspect of the invention relates to a method for hardening surface areas, such as journal surface areas, of at least two crankshafts, wherein the method comprises:
[048] during at least one stage of the method or process, simultaneously use a laser beam from a first laser source and a laser beam from a second laser source for hardening a first of said crankshafts, for example, through applying laser beams to the same or different crankshaft journals; and
[049] during at least another stage of the method, simultaneously using a laser beam from the first laser source for hardening said first of said crankshafts and a laser beam from the second laser source for hardening a second of said crankshafts.
[050] This was found to be beneficial to increase flexibility and effectiveness, reduce or avoid any downtime of laser equipment. One or more laser sources can thus be shared between a plurality of crankshafts. This is especially advantageous in the case of a product that has a configuration like a crankshaft, with a complex structure involving a plurality of journals, which are often different widths.
[051] In some embodiments of the invention, the method includes, during at least one stage of the method or process, simultaneously using a laser beam from a first laser source and a laser beam from a second laser source for hardening the first. of said crankshafts, while using a laser beam from a third laser source to harden said second of said crankshafts.
[052] A further aspect of the invention relates to an apparatus for hardening a surface area of a workpiece, wherein the apparatus comprises at least one laser source arranged to project an effective laser spot onto the surface area , and means for generating relative movement between said surface area and the effective laser spot so that said effective laser spot is moved along said surface area for the purpose of subsequently and progressively heating different portions of said area. surface to a suitable temperature for hardening. The apparatus is arranged, for example, by means of a control system suitably programmed to operate for the purpose of carrying out one or more of the methods described above.
[053] In some embodiments of the invention, the apparatus comprises at least two laser sources and is arranged for hardening, in one stage of a process of hardening the surfaces of crankshaft journals, of a journal through the application of laser beams from both said laser sources to said trunnion, and, at another stage of said process, from two trunnions by applying a laser beam from a first of said laser sources to one of said trunnions, and a beam of laser from the other of said laser sources to the other of said trunnions.
[054] In some embodiments of the invention, the machine, apparatus or system may comprise two or more laser sources arranged to operate on at least two crankshafts during at least one stage of the hardening process. For example, the machine may comprise at least three laser sources, arranged so that, during at least one stage of the hardening process, laser beams from two of these three laser sources are used to harden a first of the crankshafts and a a laser beam from one of said laser sources is used for one-second hardening of said crankshafts, while, during at least one other stage of the hardening process, a laser beam from one of these three laser sources is used for hardening of the first of said crankshafts and laser beams of two of said laser sources are used for hardening of the second of said crankshafts.
[055] In some embodiments of the invention, for a substantial part (such as at least 50%, 75%, 90%, 95% or more) of the application time of the effective laser spot on the surface area, the laser spot effective has a width (or linear extent, along the curvature of the trunnion surface) in the circumferential direction of at least 5 mm, preferably at least 7 mm, more preferably at least 10 mm, and even more preferably at least 15 mm, 20 mm, 30 mm or more, such as at least 50 mm. The use of a sufficient extension in the circumferential direction, that is, in the direction of the relative movement produced between the laser source and the trunnion surface, makes it possible to heat each portion of the surface area to be hardened for a sufficient time while completing the process of hardening within a reasonably short time. That is, a sufficient extension of the effective laser spot in the circumferential direction makes it possible to carry out the relative movement at a relatively high speed while reaching a sufficient penetration depth or hardening, without using excessively high temperatures. For this reason, a substantial effective laser spot width in the circumferential direction may be preferred. Obviously, a balance needs to be found between the power capacity of the laser used and the surface area covered by the effective laser spot, as the available power needs to be sufficient to provide sufficient heating of the area. It was concluded that when working with automobile crankshafts that have trunnions with widths of the order of one or a few cm in the first direction and that use lasers that have an output power in the range of a few kW, such as 3-4 kW, the effective point it can, for example, have a width in the circumferential direction in the order of 1 cm, while the linear relative velocity between the laser and the trunnion surface can be in the order of 60 cm/minute. For many industrial purposes it is considered that the laser beam should have a power of at least 3 kW, more preferably 6 kW.
[056] In some embodiments of the invention, said effective laser point is an equivalent or virtual laser point obtained by scanning the laser beam in the first and second directions, including directions between these two directions, i.e., directions which are oblique to the first and second directions, for example, along a trajectory or straight or curved lines, which repetitively follows a sweep pattern along which the laser point is displaced with a sweep speed, so that the Two-dimensional energy distribution during a scan cycle is determined by said scan speed, said scan pattern, laser spot size, laser beam power and the power distribution within the laser beam. In this way, one or more of these parameters can be used to dynamically adapt the two-dimensional energy distribution. This makes it possible to easily adapt and modify the size and shape of the effective laser spot, as well as the two-dimensional energy distribution within the effective laser spot, during the relative displacement between the laser source and the workpiece surface, or ie, during the crankshaft rotation around its longitudinal geometric axis, thereby adapting the two-dimensional energy distribution in order to prevent overheating of the more heat-sensitive areas such as the areas adjacent to the lubrication holes of Oil. In some embodiments of the invention, the adaptation of the energy distribution is performed by adapting at least one of said scan speed, scan pattern, laser spot size, laser beam power and the distribution of power within the laser beam, such that said energy distribution is different when heating said less heat sensitive sub-area than when heating said more heat sensitive sub-area which includes the area adjacent to a lubrication port of oil, for the purpose of preventing overheating of said area adjacent to an oil lubrication hole. In some embodiments of the invention, power distribution adaptation is performed by adapting the power of the laser beam, for example, by turning the laser beam on and off during scanning of the laser spot along the scan pattern. . For example, when using a laser such as a fiber laser, the laser beam can be turned on and off very quickly, thus making it possible to obtain a desired energy distribution by turning the laser beam on and off as it goes. the sweep pattern. In this way, heating can be achieved by turning on the laser beam during certain lines or parts of lines of the scan pattern.
[057] In some embodiments of the invention, the adaptation of the energy distribution can be (additionally) performed by adapting the scan speed while scanning the laser spot along the scan pattern. For a fixed laser beam power, a higher speed implies less energy being applied and vice versa.
[058] In some embodiments of the invention, the scanning is performed at a sufficiently high scanning speed so that the temperature oscillations at points within said effective laser spot have an amplitude less than 200 °C, preferably less than 150 °C, more preferably less than 100 °C, and even more preferably less than 50 °C, between a local maximum and the next local minimum of the temperature. In this context, the amplitude of oscillations refers to the amplitude of repetitive variations between maximum and minimum locations of the temperature curve, excluding initial substantial heating to a maximum temperature at the leading edge of the effective laser spot and subsequent cooling to a low temperature at the posterior edge of effective laser spot. For proper hardening, it is desirable that the metal quickly reach a high enough temperature and that the metal subsequently remain at said high enough temperature for a reasonable amount of time, without substantial fluctuations in said temperature, as such fluctuations can negatively affect the quality of hardening. Sweep speeds greater than 10, 25, 50, 75, 100, 150, 200, or 300 Hz (ie, sweep pattern repeats per second) may be appropriate to prevent the temperature of a hot spot from dissipating long before the spot is reheated by the laser beam during the next scan cycle. Proper hardening requires certain minimum temperatures and if a desired hardening depth is to be reached quickly, high temperatures are preferred. However, excessive temperatures can negatively affect quality due, for example, to grain size growth. Thus, an agreed temperature needs to be found and deviations from that temperature should be as small as possible. Therefore, a high sweep speed in terms of cycles per second may be preferred to reduce the amplitude of oscillations or temperature variations.
[059] In some embodiments of the invention, said energy distribution has a higher energy density in a portion or leading edge of said effective laser spot than in a portion or trailing edge of said effective laser spot, so that an area swept by the effective laser spot is first receiving laser irradiation with higher average power and is subsequently receiving laser irradiation with lower average power. This increases effectiveness as an appropriate hardening temperature is quickly reached, in order to reduce the time during which the effective laser spot needs to be applied to a certain area in order to achieve a required hardening depth. In this way, it takes less time to complete the hardening of, for example, the surface of a sleeve.
[060] In some embodiments of the invention, the method comprises the step of using a different scanning pattern for the laser beam within said effective laser spot, in said sub-area more sensitive to heat compared to said sub-area less sensitive to heat. heat.
[061] In some embodiments of the invention, the method comprises the step of adapting said energy distribution by adapting the scan speed so that it is different in at least part of said effective laser spot, in said sub-area more sensitive to heat compared to in said sub-area less sensitive to heat.
[062] In some embodiments of the invention, said effective laser spot comprises a front portion with a selected energy distribution and density for heating a portion of the workpiece surface to a hardening temperature, an intermediate portion with a distribution and an energy density (such as a very low energy density, such as zero power or near-zero power) selected for the purpose of allowing the cooling of a portion of the heated surface for sudden cooling, and a posterior portion that has a distribution and a selected energy density for heating the quenched portion for the purpose of hardening the same. In general, many work pieces such as crankshafts require, in addition to hardening them, tempering in order to reduce hardness, enhance malleability and reduce brittleness. For hardening, the workpiece must be heated to a temperature that is generally lower than the temperature used for hardening. When a workpiece has been hardened using a laser treatment, hardening can take place in a furnace or oven, but it is also possible to harden it by applying a laser treatment similar to that used for hardening, but with a density and/or different energy distribution. For example, in the case of a crankshaft, hardening can take place by applying a hardening cycle after the hardening cycle. For example, after a trunnion has hardened 360 degrees, the effective laser spot can again be moved around or along the trunnion, this time to harden the trunnion. However, it is also possible to provide hardening and tempering in the same cycle or process step through the use of an effective laser spot that includes: an anterior portion for heating the workpiece surface to a desired hardening temperature and to maintain the surface at said temperature for a sufficient time in order to obtain the desired hardening depth; an intermediate portion with a low energy density, such as an energy or power density of substantially 0 W/cm2, for the purpose of allowing the heated portion to cool for the purpose of producing quench cooling or quench self-cooling thereof; and a back portion having an energy distribution and density for the purpose of reheating the quenched portion to the point necessary for quenching as desired. Thus, to produce both quenching and quenching, it may suffice to let the effective laser spot sweep the surface to be treated once, for example, in the case of a crankshaft trunnion surface, by rotating the crankshaft once around its geometric axis of rotation.
[063] In the different aspects of the invention described above which include scanning the laser beam or laser spot along and/or through a portion of the workpiece, such scanning can be performed so that the laser spot repetitively follows a scan pattern comprising a plurality of segments, and wherein at least one parameter value influencing said two-dimensional energy distribution is associated with each of said segments, e.g. stored in a memory of a control system with the purpose of being used to adapt the operation in correspondence with the respective segment each time the laser spot is moved along said segment. Said at least one parameter value can be dynamically adapted during operation so that said at least one parameter value is different for at least one of said segments when the effective laser spot is heating said more heat sensitive sub-area when heating said sub-area less sensitive to heat. For example, for a given segment, different parameter values (or combinations of parameter values) can be stored in different memory locations and, depending on the sub-area being heated, the parameter value can be pulled from a memory location or from another memory location. However, this is just an example, and also other implementations are included in the scope of the invention. It was concluded that the use of a segmented sweep pattern makes it easy to find and implement a power distribution that is tailored to the specific design of a crankshaft. By adapting one or more parameters that influence the two-dimensional energy distribution, it is easy to modify the energy distribution in order, for example, to apply less power/energy in correspondence with more heat-sensitive portions of the workpiece, such as the area around the edges of a crankshaft oil lubrication hole. In this way, an operator can, by assigning different values to certain parameters in correspondence with each segment, define different energy distributions, and by switching between different energy distributions during hardening of a portion of a workpiece, such as On the surface of a crankshaft journal, adequate hardening can be achieved while avoiding local overheating of heat-sensitive portions. Using a segmented scan pattern and assigning parameter values on a per segment basis makes it easy to find appropriate values, for example, with a few trial and error tests. For example, to accommodate an oil lubrication hole, the values assigned to certain segments can be selected to reduce the energy applied adjacent to said oil lubrication holes when the effective laser spot arrives in the corresponding sub-areas of the workpiece.
[064] Parameter values can be indicative of at least one of scan speed, laser spot size, laser beam power, power distribution within the laser beam, corresponding segment length, and corresponding segment orientation. In many embodiments of the invention, laser beam power and/or sweep speed may be preferred parameters.
[065] In some embodiments of the aspects of the invention described above, the method comprises the step of reducing the energy density in an earlier portion of the effective laser spot when the effective laser spot is arriving at a previously hardened portion of said area of surface, as in a previously hardened portion of a crankshaft journal hardened by the displacement of the effective laser spot around the journal in a circumferential direction. Thereby, undue heating of an already heated and hardened portion of the journal can be prevented. In some embodiments of the invention, the power/energy density at the leading edge of the effective laser spot is merely reduced, but the effective laser spot continues to travel, for example, around the trunnion in the circumferential direction, in order to reheat the portion hardened to a certain extent, with the purpose of tempering it. In other embodiments of the invention, the method comprises the step of, when the effective laser spot is arriving at a previously hardened portion of said surface area, such as a previously hardened portion of a crankshaft trunnion hardened by displacement of the point of laser effective around the trunnion in a circumferential direction, interrupting the movement of said effective laser spot in an anterior portion of said effective laser spot, while a posterior portion of said effective laser spot continues to move in said circumferential direction , thereby progressively reducing the size of said effective laser spot in said circumferential direction, until said effective laser spot disappears. That is, the effective laser spot stops substantially when it reaches the previously hardened portion, ie, for example, the leading edge stops and the trailing edge reaches the leading edge, completing the hardening cycle.
[066] In both cases, the implementation of the method can be substantially facilitated if the effective laser spot is composed of segments, like segments of a scan pattern. The reduction or cancellation of the effective laser spot starting at its leading edge can be achieved by adapting the energy density in said segments, such as by reducing the beam power and/or increasing the scan speed, and/or by simple cancellation or rearrangement of segments. Thus, the segmented approach in combination with the use of two-dimensional scanning of the laser beam to create the effective laser spot provides flexibility and makes manipulation by the skilled element easy, for example in the case of laser hardening of sleeves. crankshafts in the circumferential direction, from the arrival of the effective laser point on the previously hardened portion of the trajectory.
[067] The different aspects described above can be combined with each other, when they are compatible with each other. BRIEF DESCRIPTION OF THE DRAWINGS
[068] To complete the description and in order to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate different ways of carrying out the invention, which should not be interpreted as restricting the scope of the invention, but only as examples of how the invention can be carried out. The drawings comprise the following figures:
[069] Figure 1 is a schematic perspective view of a crankshaft as known in the art.
[070] Figure 2 is a schematic perspective view of a system according to a possible embodiment of the invention.
[071] Figure 3 is a schematic front elevation view of a portion of the laser source 1 and a portion of a workpiece, according to a possible embodiment of the invention.
[072] Figures 4A-4C schematically illustrate how the power distribution of an effective laser spot is adapted when hardening the area around a crankshaft oil lubrication hole.
[073] Figures 5A and 5B are schematic top views of a section of a workpiece at two different times in the hardening process, with an effective laser spot created using a polygonal scan pattern.
[074] Figure 6 schematically illustrates an effective laser spot created by a scanning pattern comprising a plurality of parallel lines.
[075] Figures 7A and 7B illustrate a possible scan pattern comprising a plurality of parallel lines.
[076] Figures 8A and 8B illustrate a scan pattern to create an effective laser spot according to an embodiment of the invention.
[077] Figures 9A and 9B illustrate a scan pattern to create an effective laser spot according to another embodiment of the invention.
[078] Figures 10A-10C schematically illustrate how two laser sources can be used to harden crankshaft journals.
[079] Figures 11A and 11B schematically illustrate how laser beams from two laser sources can provide an effective laser spot on the surface of a crankshaft trunnion.
[080] Figures 12A and 12B schematically illustrate how, in a possible embodiment of the invention, the apparatus or system can comprise two or more lasers, which can be shared between two or more crankshafts. DESCRIPTION OF WAYS TO CARRY OUT THE INVENTION
[081] Figure 2 illustrates a system according to a possible embodiment of the invention. The system comprises a frame structure that accommodates a laser source 1 mounted on a laser carrier 11 which is displaceable in the vertical direction, parallel to a vertical axis Z of the system, by means of the first laser carrier driving means 12 , for example, by means of a servomotor or any other suitable driving means. On the other hand, the laser source 1 can also be driven horizontally, parallel to a horizontal X axis of the system, along a horizontal trajectory 14, driven by means of the second laser conveyor driving means 13, like another servomotor or other suitable means of conduct.
[082] On the other hand, the system comprises two workpiece conveyors 20, wherein each workpiece conveyor can accommodate two parallel workpieces 1000 (in the present embodiment, the workpieces are crankshafts) and includes means of driving (not shown) to rotate each workpiece along a central geometric axis (in the present embodiment, the central geometric axis corresponds to the longitudinal geometric axis passing through the centers of the crankshaft main journals), wherein said geometric axis it is parallel to the X axis of the system. On the other hand, each workpiece carrier 20 is associated with workpiece carrier driving means 21 (such as a servomotor or any other suitable driving means) arranged to move the workpiece carrier horizontally, parallel to a Y axis of the system, perpendicular to the X axis.
[083] References to horizontal and vertical directions are used only to simplify the explanation, and any other orientation of the geometric axes is obviously possible and falls within the scope of the invention.
[084] In the present case, the laser source 1 is first used to harden the relevant parts of the surface of one of the workpieces 1000 in a first of the workpiece carriers 20, then it is used to harden the relevant parts of the surface of the other workpiece 1000 on said first of the workpiece carriers 20 and then it is moved along path 14 so that it faces the second of the workpiece carriers 20 , to harden the surfaces of the workpieces 1000 arranged thereon. Although laser source 1 operates on the workpieces in the second of the workpiece conveyors, the workpieces in the first of the workpiece conveyors can be unloaded and replaced with new workpieces to be handled by the source. laser and vice versa.
[085] Obviously, there are many alternative possibilities. For example, there may be only one workpiece per workpiece conveyor, or there may be more than two workpieces per workpiece conveyor. There may be one laser source per workpiece conveyor (i.e. a second laser source conveyor with its corresponding laser source can be added to path 14) . Furthermore, several arrangements like the one in figure 2, or variables thereof, can be placed in parallel. Furthermore, each laser carrier 11 can be provided with more than one laser source 1 so that several workpieces on a workpiece carrier can be subjected to laser hardening treatment simultaneously. The relationship between the number of laser sources, the number of workpiece carriers and the number of workpieces can be chosen in order to optimize the use of the most expensive parts of the system and to optimize productivity, for example, allowing loading and unloading of workpieces without interrupting system operation. In some embodiments of the invention, a plurality of laser sources can be used to direct laser beams simultaneously to the same crankshaft, for example, to act simultaneously on different crankshaft journals or the same crankshaft journal.
[086] In some embodiments of the invention, when the workpiece is a 1000 crankshaft with 1001 main trunnions and 1002 connecting rod trunnions, during the heat treatment of the 1001 crankshaft main trunnions, the laser source does not move in the direction of the Z axis and the workpiece carrier does not move in the Y axis direction, as the main journal surface is circular and symmetrical around the crankshaft rotation axis. In some embodiments of the invention, there may be movement of the laser source and/or workpieces along the X axis, if it is necessary to apply the laser heat treatment along the entire length of the main journal in the direction of the X axis. This depends on the power capability of the laser source and the ability of the scanning means (not shown) to shift the laser beam in the direction of the X axis. main trunnion 1001 along its entire length in the direction of the X axis, there may not be a need to move the laser source 1 in the direction of the X axis during heat treatment of, for example, one of the main trunnions 1001 of a crankshaft, but only when switching from treating one trunnion to treating another; the same applies to the heat treatment of, for example, connecting rod journals 1002 of a crankshaft.
[087] Meanwhile, during heat treatment of a connecting rod journal 1002, whose central axis is radially displaced from the central axis of the main journals, during rotation of the respective crankshaft workpiece 1000 on the workpiece carrier 20 , the laser light source 1 is moved vertically parallel to the geometric axis Z and the workpiece carrier 2 is moved horizontally parallel to the geometric axis Y, in order to maintain a constant distance between the laser source (as the output of the laser source's scanning means, or the surface of a lens) and the surface onto which the laser beam is projected. In other embodiments of the invention, the crankshafts can be moved parallel to the Z and Y geometric axes. Additionally or alternatively, the laser source can be arranged to be movable parallel to the Z and Y geometric axes.
[088] The operation of the first 12 and second 13 laser conveyor driving means, as well as the operation of the workpiece carrier driving means 21 of the driving means for rotating the workpieces 1000 on the workpiece carriers working 20, can be controlled by electronic control means such as a computer, computer system or PLC (not shown in figure 2).
[089] Laser source 1 includes a scanning system arranged to change the direction of the laser beam. Such scanning systems are well known in the art, and often include one or more scanning mirrors, the angles of which can be changed in accordance with scanning functions, such as sine functions, triangular functions, etc., under the control of a computer. A geometry axis scanning system (eg a scanning system with a scanning mirror pivoting around a geometry axis or the like) can be used to scan the laser beam parallel to the X axis, ie. mode perpendicular to the direction of movement of the workpiece surface 1000 relative to laser source 1 due to the rotation of the workpiece 1000. A quick sweep across the relevant portion of the surface can thus create a virtual point that has a extension in the X direction much greater than the extension of the unscanned point: in this way, the original point becomes a wider virtual point (with a greater extension in the X direction), but with a lower power density, since the beam power is distributed over a larger area.
[090] With a two-axis scanning system (for example, with a scanning system that has a biaxial mirror or two uniaxial mirrors), the laser beam can be moved in two directions, for example, on one side, parallel to the X axis and, on the other hand, parallel to the Y axis, and combinations thereof. Thus, in addition to sweeping the surface perpendicular to the direction of movement of the surface in relation to the laser source, that is, in addition to sweeping the surface "along the" surface of the trunnions in the direction of the geometric axis X, the beam of laser can also sweep the surface in the direction of its movement, that is, parallel to the geometric Y axis; thus, the surface of a crankshaft journal can also be swept in the circumferential direction of the journal. In addition, the laser beam can describe trajectories that combine motion in the X direction and the Y direction. Thereby, the beam can follow trajectories that have complex shapes, such as rectangular, oval, trapezoidal, etc. The laser dot can be swept over the surface to form a virtual filled rectangle that has a substantial height in the Y (or W) direction (for example, following a meander pattern within a rectangular boundary or following a plurality of separate lines within of said boundary), or to repetitively outline the edges of a rectangle or any other geometrical shape. In this way, using the capability of the scanning system, an effective virtual laser spot or equivalent can be created which has a desired length and shape in either the X direction or the Y or W direction. termed XYZ sweeper, in addition to the possibility of movement in the X and Y directions, a focusing lens is provided, which can be shifted in the Z direction by some kind of conduction means, thereby allowing a dynamic size adaptation. of the laser point. Thereby, both the position of the stitch and its size can be controlled and adapted to optimize the hardening process. Furthermore, as an alternative or in addition to shifting a focusing lens or the like, the laser spot size can be controlled and adapted by moving the laser source parallel to the Z axis, using the first means of laser conveyor driving. Furthermore, the system may include means for varying the power distribution at the laser spot, as is known, for example, from DE-3905551-A1 mentioned above.
[091] Figure 3 schematically illustrates the laser source 1 which includes a schematically illustrated two-axis scanning system 3, based on a biaxial mirror or two uniaxial mirrors and arranged to deflect an incident laser beam 2 in the vertical plane parallel to the X axis and in the vertical plane parallel to the Y axis; angle α represents the maximum sweep in the vertical plane parallel to geometric axis X, and angle β represents maximum sweep in the plane parallel to geometric axis Y. Figure 3 schematically illustrates laser source 1 placed above a workpiece and , more specifically, above the main journal 1001 of a crankshaft, which includes an oil lube hole 1003 and which is rotated on the workpiece carrier (not shown) in the direction suggested by the arrow. In figure 3 a portion or section 1006 is schematically illustrated that can be scanned by the laser spot due to the scanning of the laser beam. Thus, using this type of laser source, a small laser dot projected onto the top of the workpiece can be replaced by a larger or equivalent virtual dot, obtained by repetitively scanning a pattern at high speed. which has any desired shape, in section 1006 which is determined by the maximum scan allowed by the scanning system, according to the angles α and β. In this way, instead of heating a single small spot with the laser beam, a larger area can be heated (but with less power per unit area) over a period of time by scanning that area with the laser beam. . Or in other words: instead of providing a large dot (such as a large rectangular dot) with the use, for example, of suitable optical elements, a corresponding distribution of power can be achieved by scanning a smaller and larger dot. power intensity over a larger area. This involves an important advantage: it provides the possibility to dynamically apply different amounts of energy to different portions of the surface, by adapting the sweep pattern, the speed of the sweep movement, the beam power and/or the spot size, of according to different characteristics of different portions of the surface, for example depending on the sensitivity to heat and the risk of damage from overheating. For example, the scan pattern, scan speed, beam power and/or laser spot size can be chosen (and dynamically adapted during the hardening process) in order to limit the amount of heating energy applied to the surface in the vicinity of oil lubrication holes or in the vicinity of recessed fillets. To obtain adequate depth and hardening quality, scanning is performed repetitively and preferably at a high frequency such as more than 10 Hz or more preferably more than 50, 100, 150, 200 or 250 Hz, in order to avoid substantial variations in temperature in the heated area.
[092] Figures 4A-4C show how the energy distribution of an effective laser spot can be adapted to accommodate an oil lubrication hole. The oil lubrication hole 1003 is positioned in a surface of a crankshaft trunnion, and said surface extends in a first direction W, viz., the circumferential direction, and in a second direction parallel to the geometric axis of rotation of the crankshaft. In Figure 4A, an equivalent substantially rectangular effective laser spot 5 is used, which has a front portion 5A with higher power density and a trailing portion 5B with lower power density. However, as shown in figure 4B, when oil lubrication hole 1003 approaches the effective laser point due to the relative movement between the crankshaft surface and the laser source due, for example, to the crankshaft rotation around its longitudinal geometric axis, the energy distribution is substantially adapted by reducing the energy or power density towards the center of the front portion 5A, in order to avoid overheating the area adjacent to the oil lubrication hole 1003. , the effective laser spot is substantially U-shaped. Subsequently, once the oil lubrication hole 1003 has passed the anterior portion 5A, the original energy distribution in the anterior portion is restored, while the energy distribution in the anterior portion is restored. rear portion 5B is adapted to accommodate oil lube hole 1003 by reducing power or energy density. towards the center of the posterior portion. In the present document, the effective laser spot 5 substantially adopts an inverted U-shape as shown in figure 4C. That is, although the oil lubrication hole passes through the effective laser spot, the energy distribution is adapted in order to apply less energy to the more heat sensitive area adjacent to the oil lubrication hole than is applied to the surface so that it is hardened in the opposite direction to said oil lubrication hole. The area around the oil lubrication hole can be hardened without damaging the most heat sensitive sub-area adjacent to the oil lubrication hole; the side portions of the U-shaped effective laser spot serve to harden the areas on the sides of the oil lubrication hole. The change in energy distribution illustrated in Figures 4A to 4C can be obtained, for example, by adapting the scan pattern and/or by adapting the way in which the beam power is distributed along the scan pattern (by example, by adapting the way the laser beam is switched on and off by switching during different segments of the scan pattern) and/or by adapting the scan speed in correspondence with different segments of the scan pattern, etc.
[093] A simple sweep pattern may comprise a simple pattern or a polygon, as illustrated schematically in Figures 5A and 5B, which are top views of a portion of a crankshaft, viz. a main trunnion 1001 of the crankshaft, during two different stages of a hardening process. In Figures 5A and 5B, the sweep pattern extends almost over the entire width of the journal, substantially from one of the fillets 1004 to the other. The sweep pattern is designed to imply lower power density in the most heat sensitive subarea around oil lube hole 1003 (see figure 5B), than in the least heat sensitive subarea or region farthest from the hole. oil lubrication (see figure 5A); In this case, this is achieved by a greater height of the trapezoidal sweep pattern when the area around oil lube hole 1003 is swept. In addition, the area adjacent to fillets 1004 is considered a heat sensitive area, for example, due to the use of recessed fillets. In this way, the scan pattern is arranged to provide a lower power density in this area as well; this is achieved using a trapezoidal sweep pattern whereby, with a substantially constant sweep speed, less energy will be received in the vicinity of the fillets than if a rectangular sweep pattern is used. Instead of using a trapezoidal pattern, only two parallel lines can be used, such as the top and bottom lines of the trapezoid shown in figures 5A and 5B.
[094] Now, regardless of whether only two parallel lines are used, or these two lines are interconnected to form a polygon as illustrated in Figures 5A and 5B, one problem with this approach is that the actual laser spot size limits the height of the polygon, that is, in a case like that in figures 5A and 5B, the height of the polygon in the circumferential direction, or the distance between the two parallel lines in the circumferential direction. It is important that the temperature to which the material is heated at the effective laser spot is substantially constant during a substantial part of the heating, to avoid variations that could negatively affect the quality of the hardening process. Thus, the height of the polygon is, to a substantial extent, limited by the diameter of the actual laser spot. However, it is often desired that the effective laser spot has a substantial extension in the direction of displacement, that is, in the case illustrated in figures 5A and 5B, in the circumferential direction: this is due to the fact that in order to ensure a depth of sufficient hardening, each point of the surface to be hardened must remain for a long enough time within the area that is heated by the effective laser spot. On the other hand, in order to achieve high productivity in terms of units per hour, the effective laser spot must move as fast as possible. In this way, a substantial extension of the effective laser spot in the direction of travel is desired.
[095] For a given size of the actual laser spot, a substantial extension of the effective laser spot in the direction of displacement can be achieved by providing a scan pattern that comprises more than two lines arranged one after the other in the direction. of displacement, as illustrated schematically in Figure 6, wherein the effective laser spot 5 is created by a plurality of parallel lines extending in the second direction perpendicular to the first direction W, i.e. the direction of relative movement between the point of effective laser and the surface area that is hardened.
[096] This scan pattern can be created by repetitively scanning the actual laser spot in the second direction perpendicular to the first direction the effective laser spot travels, shifting the laser beam a small distance in the first direction between each step in order to draw a plurality of parallel lines. Once the actual laser spot has completed the scan pattern, it will return to its original position and run the scan pattern again. The frequency with which this occurs is preferably high, in order to avoid unwanted temperature variations at the effective laser spot 5.
[097] The laser beam can be turned off while moving towards a new line to be followed and/or between ending the last line of the scan pattern and returning to the first line of the scan pattern. However, turning the laser beams on and off takes time and can slow down the scan frequency. Furthermore, the time during which the laser beam is turned off is wasted time in terms of using the laser effectively for heating.
[098] Figures 7A and 7B illustrate a possible scan pattern comprising three main lines a-c (illustrated as solid lines) of the scan pattern, and dashed lines that illustrate the trajectory that the laser spot follows between said lines. In Figure 7B, the arrows schematically illustrate the path in which the actual laser spot travels over the surface to be hardened while following the sweep pattern.
[099] Now, this scan pattern involves a problem in the sense that the heat distribution will not be symmetrical. The same applies if, at the end of the pattern, at the end of the last line c (ie from the arrowhead of line c in figure 7B), the laser beam returns vertically to line a.
[0100] A more symmetrical distribution of energy with respect to the geometric axis W can be obtained with a scanning pattern as shown in figures 8A and 8B, which also comprises three parallel lines ac interconnected by lines d followed by the real laser spot when moving between these lines. As illustrated in 7B, the laser beam, from the beginning of the first line a, moves as follows: a - d1 - b - d2 - c - d3 - b - d4.
[0101] That is, the actual laser spot travels along midline b twice as often as it travels through the first line and the last line: it travels along midline b twice for each time it scrolls along the first line a and the last line c. Thus, a completely symmetrical sweep pattern can be obtained, with respect to the geometric axis W, that is, with respect to the circumferential direction.
[0102] The energy distribution along the geometric axis W can be defined by adjusting, for example, the distance between lines a-c and the speed with which the laser beam moves along the lines. By adjusting the speed and/or the scan pattern, the power distribution can be dynamically adapted without turning the laser beam on and off or without substantially modifying the power of the laser beam. For example, if the energy needs to be distributed substantially equally along the effective laser spot, the laser beam may travel faster along the middle line b than along the first line a and the last line c . For example, the actual laser spot speed along line b can be double the actual laser spot speed along lines a and c. In some embodiments of the invention, the effective laser spot speed along lines d1-d4 may also be substantially greater than the effective laser spot speed along lines a and c.
[0103] In this way, the adjustment of the energy distribution can be achieved by adapting the distribution of lines, such as the first line, the last line and the intermediate lines ac, and by adapting the speed of the laser spot to the along the different segments ad (including d1-d4) of the scan pattern. The segment distribution and segment speed can be dynamically modified as the effective laser spot moves along the surface area to be hardened, such as around a crankshaft journal, in order to adapt the distribution. of energy to prevent overheating of more heat-sensitive subareas, such as subareas adjacent to oil lubrication holes, recessed fillets, or a previously hardened area that the effective laser spot approaches at the end of its travel around the circumference of a surface area to be hardened, such as the surface of a crankshaft journal. In addition, the scan pattern can be adapted by adding or deleting segments while moving the effective laser spot along the surface to be hardened.
[0104] The same principle can be applied to other scan patterns, such as the scan pattern in figures 9A and 9B, which includes an additional midline b. In this document, the trajectory followed by the actual laser point is: a - d1- b - d2 - b - d3 - c - d4 - b - d5 - b - d6.
[0105] Figures 10A-10C schematically illustrate how two lasers or laser sources 1 and 1A can be used to harden the crankshaft surfaces or journals, which can be advantageous, for example, when the crankshaft has journals that have different widths. The crankshaft 1000 of figures 10A-10C includes main journals 1001 that have a first width, and connecting rod journals 1002 that have a second width that is, for example, approximately twice the first width. In Figure 10A, laser beams 2 and 2A from laser sources 1 and 1A, respectively, are both applied to the connecting rod journal, so that the combined power and scanning capability of these laser sources can be used to provide, on the surface area to be hardened, an effective combined laser spot suitable for fast and effective hardening of the connecting rod sleeve. In another stage of the hardening process, two main journals are hardened simultaneously, each by a single laser source, as illustrated in Figures 10B and 10C. Figures 11A and 11B show how the portions P and PA heated by the first laser beam 2 and the second laser beam 2A, respectively, can be more or less superimposed. Substantially overlapping portions may be preferred to optimize the uniformity of hardening and to avoid any risk of boundary effects where the two portions meet. However, as suggested by figure 10A, it may sometimes be of interest to let each of the laser beams harden only a part of the area to be hardened, in relation to the extension of said area in the second direction, ie along the axis crankshaft geometric. This can sometimes be useful to subsequently harden several crankshaft journals without moving the laser source or crankshaft in said second direction, while overcoming the problem that counterweights and other radially protruding parts of the crankshaft can interfere with the laser beam. This is easily understood when viewing figures 10A-10C: in figure 10A, the first laser beam 2 is applied to a portion P and the second laser beam 2A is applied to a portion PA of the connecting rod sleeve 1002, placed substantially on the side side by side and not substantially overlapping each other, according to Figure 11A. In Figures 10B and 10C, the laser beams have been reoriented to impinge on the two main journals 1001, without displacing the laser sources or the crankshaft, parallel to the geometric axis of rotation of the crankshaft.
[0106] In some embodiments of the invention, two or more laser sources may be shared between two or more crankshafts, thus improving flexibility and effective use of laser sources and available laser power. For example, figures 12A and 12B illustrate a possible arrangement, where the machine or system is arranged to simultaneously harden two or more crankshafts. In the illustrated arrangements, the machine comprises three laser sources 1, 1A and 1B, associated with the respective scanning means 3 . During at least one stage (figure 12A) of the hardening process, the 2, 2A laser beams of two (1, 1A) among these three laser sources are used to harden a first of the crankshafts (figure 12A illustrates how these laser sources 1, 1A are used to jointly harden a crankshaft rod end 1002) and a laser beam 2B from one of said 1B laser sources is used to harden another of said crankshafts (the figure 12A illustrates how laser beam 2B is used to harden a main trunnion 1001), while, during at least another stage of the hardening process (figure 12B), a laser beam 2 from one of these three laser sources 1 is used to harden the first of the crankshafts (namely, in figure 12B, a main journal 1001 thereof) and laser beams 2A, 2B of two of said laser sources 1A, 1B are used to harden another of said crankshafts (in the stage shown in fig. ra 12B, a connecting rod sleeve thereof). That is, sharing one or more laser sources among a plurality of crankshafts can be used to optimize equipment usage and reduce costly laser equipment downtime, improving efficiency and productivity.
[0107] Reference numbers used in this description: 1, 1A, 1BLaser source 2, 2A, 2BLaser beam 3Scan system 5Effective laser spot 5Front portion of effective laser spot 5BRear portion of effective laser spot 11Laser conveyor 12first laser driving means carrier for laser source vertical movement 13second laser driving means carrier for laser source horizontal movement 14horizontal path for laser source movement 20workpiece carrier 21workpiece carrier driving means work 1000crankshaft 1001main trunnion 1002rod trunnion 1003oil lubrication holes 1004fillets 1005surface perpendicular to the trunnions 1006area or section that can be scanned by laser beam a, b, c, d1, d2, d3, d4, d5, d6 X scan pattern segments , Y, Zdirections in space Wa circumferential direction P, PPortions of a crankshaft trunnion
[0108] In this document, the term "effective laser spot" refers to an area onto which a laser beam is effectively projected for the purpose of illuminating and heating the area. The effective laser spot can be a laser spot obtained by transforming an original laser beam using optical elements for the purpose of shaping the laser spot and for the purpose of distributing power over the effective laser spot in a desired manner, or a virtual laser spot or equivalent obtained by rapidly and repetitively scanning the laser beam which follows a scanning pattern for the purpose of repetitively applying the laser beam to the same or substantially the same area, of so that the heating effect of the laser beam is substantially equal to what it would be if a stationary laser beam had been used with a power distribution that corresponds to the power distribution across the virtual laser spot or equivalent during a scan cycle. Here, the term "quickly" means that the sweep speed is much greater than the speed of relative movement between the laser source and the crankshaft surface, for example, in the circumferential direction, so that portions of the surface area to be hardened are repetitively heated by the laser spot. For example, typically the scan speed can be selected so that, for example, at least 10, 50 or 100 scan cycles per second are achieved. Preferably, when the effective laser spot is a virtual or equivalent laser spot obtained by repetitively scanning a true or real laser spot over the surface area to be hardened, this scanning preferably takes place in two dimensions, and the size of the virtual laser spot in any of said dimensions is preferably at least 2, 3, 4, 5, 10, 20 or more times the size of the true or real laser spot in said dimension, e.g. direction parallel to a geometric axis of rotation of a crankshaft and in the circumferential direction of a crankshaft journal. For example, it may be preferred that, for at least 50% of the time of application of the effective laser spot on the surface area, the effective laser spot has a width in the circumferential direction of at least 5 mm, preferably at least 7 mm, more preferably at least 10 mm, and even more preferably at least 15 mm, 20 mm, 30 mm or more, such as at least 50 mm. Such substantial extension can provide high productivity combined with sufficient hardening depth.
[0109] The term scanning is preferably intended to imply the movement of the laser beam, and the scanning pattern is preferably intended to refer to the pattern that the beam would follow on a stationary surface, that is, without consider the relative movement between the laser source and the workpiece surface.
[0110] In general, the growth of the treated area or segment is achieved by a relative movement between the effective laser spot and the surface to be hardened, through the movement of the effective laser spot and said surface relative to each other, for example, in the case of a crankshaft, by rotating the crankshaft. In order to achieve a sufficient hardening depth, for example a hardening layer depth of 1000 µm or more, it is preferred that substantially each portion of the surface area to be hardened remains within the effective laser spot area by an amount enough time, as typically, for example, in the case of crankshaft journals, 0.5-5 seconds, like 1-3 seconds, so that not only the surface temperature is high enough, but so that the part is work is sufficiently heated to the required depth. Increasing the laser beam power density is not a substitute for sufficient warm-up time, as the surface area should not be overheated as this would cause damage to the workpiece. Therefore, the surface temperature must be within a suitable range for a sufficient time. Therefore, a substantial size of the effective laser spot is desired, in one dimension in order to provide a sufficient width of the hardening path (for example, in order to cover substantially the entire width of a crankshaft journal), and in another dimension in order to allow a high relative speed between the effective laser spot and the surface to be treated (thus providing a high production rate), while allowing the portions to be hardened to remain long enough within the effective laser spot in order to achieve the desired or required hardening depth.
[0111] In this document, the term "crankshaft" preferably refers to the part of an engine that transforms linear reciprocating piston movement into rotation, for example, to the type of crankshaft that is used in internal combustion engines, such as those used in many types of motor vehicles, such as trucks, automobiles and motorcycles.
[0112] In this document, the depth of hardening preferably refers to the effective layer depth, which preferably refers to the perpendicular distance from the surface of the hardened layer to the farthest point where a specified level of hardness is sustained. Said level may be in the range, for example, 40-55 HRC, preferably 45 HRC. In the field of crankshafts, desired hardness levels are generally decided by considering the carbon content of the steel, but a typical level is 45 HRC. In the context of the present document and regarding hardening of crankshaft journals, a hardening depth of at least 1000, 2000 or 3000 µm is preferred.
[0113] Another aspect of interest may be the level or depth to which the 100% transformed martensite can be observed. In the context of the present document and regarding the hardening of journals of a crankshaft, that depth can preferably be at least 200, 300, 500, 800, 1000 µm or more.
[0114] When a segmented scan pattern is used, a scan speed of at least 300 segments per second may be preferred, while speeds of, for example, at least 600, 1000, 5000 and 10000 segments per second may be more preferred, preferably in combination with scan pattern repetition frequencies of at least 10 Hz, more preferably at least 50 Hz, even more preferably at least 100 Hz or 200 Hz.
[0115] Although the present invention has been described in several references to the surface hardening of crankshafts, the scope of the invention is by no means limited to the surface treatment of crankshafts.
[0116] In this text, the term "comprises" and its derivations (such as "comprises", etc.) should not be understood in an exclusive sense, that is, these terms should not be interpreted as excluding the possibility that what described and defined may include additional elements, steps, etc.
[0117] On the other hand, the invention is obviously not limited to the specific modality(s) described in this document, but also covers any variations that may be considered by any person skilled in the art (by example, with respect to the choice of materials, dimensions, components, configuration, etc.), included in the general scope of the invention as defined in the claims.

权利要求:
Claims (18)
[0001]
1. METHOD OF LASER HARDENING OF A SURFACE OF A WORKPIECE, wherein the workpiece comprises at least one surface area to be hardened, wherein the method is characterized by comprising: projecting a laser beam (2) from a laser source (1) over said surface area, for the purpose of producing a laser spot on said surface area; generating a relative movement between the surface of the workpiece (1000) and the laser source (1), thereby allowing the laser spot to be subsequently projected onto different portions of said surface area; during said relative movement, repetitively sweeping the laser beam (2) along the respective portion of said surface area in two dimensions, following a sweeping pattern in order to produce an effective two-dimensional laser spot (5) over the said surface area, wherein said effective laser spot (5) has an energy distribution, wherein, due to relative motion, said effective laser spot travels along said surface area; wherein said scan pattern comprises at least three segments (a, b, c), and wherein said laser beam scanning is performed such that said laser beam follows at least one of said segments (b) more often than follows at least one other of said segments (a, c).
[0002]
2. METHOD according to claim 1, characterized in that the scan pattern comprises at least three parallel lines (a, b, c) distributed one after the other in a first direction, wherein said lines extend in a second direction , wherein said at least three lines comprise a first line (a), at least one intermediate line (b) and a last line (c) arranged one after the other in said first direction, wherein said scanning beam of laser is performed such that said laser beam or actual laser spot follows said intermediate line (b) more often than said laser beam follows said first line (a) and/or said last line ( ç).
[0003]
3. METHOD according to claim 1, characterized in that the scan pattern comprises at least three parallel lines (a, b, c) distributed one after the other in a first direction, wherein said lines extend in a second direction , wherein said at least three lines comprise a first line (a), at least one intermediate line (b) and a last line (c) arranged one after the other in said first direction, and wherein the scanning of the beam of laser is performed so that the laser spot is scanned along said lines according to a sequence, according to which, the laser spot, after following said first line (a), follows said intermediate line ( b), said last line (c), said intermediate line (b) and said first line (a) , in that order.
[0004]
4. METHOD, according to any one of claims 2 or 3, characterized in that said scan pattern comprises a plurality of said intermediate lines (b).
[0005]
5. METHOD according to any one of claims 2 to 4, characterized in that the laser spot is moved with a higher speed along said at least one intermediate line (b) than along said first line (a) and last line (c).
[0006]
6. METHOD according to any of claims 2 to 5, characterized in that the scan pattern additionally comprises lines (d1-d6) extending in said first direction, between the ends of the first line, the last line and the intermediate line , thereby said laser spot follows said lines (d1-d6) which extend in said first direction when moving between said first line (a), said intermediate line (b) and said last line (c ).
[0007]
7. METHOD according to claim 6, characterized in that the laser spot is moved with a higher speed along said lines (d1-d6) extending in the first direction than along said first line (a) and of said last line (c).
[0008]
8. METHOD, according to any one of the preceding claims, characterized in that the laser spot is moved along said scanning pattern while maintaining constant laser beam power.
[0009]
9. METHOD, according to any one of the preceding claims, characterized in that said work piece is a crankshaft (1000).
[0010]
10. METHOD OF LASER HARDENING SURFACE OF TRUNNIONS (1001, 1002) OF A CRANKCASE (1000), wherein said crankshaft has at least one first journal (1001) having a first width and at least one second journal (1002 ) having a second width, wherein said second width is greater than said first width, wherein each of said journals comprises a surface area to be hardened, wherein said surface area extends over a first direction that corresponds to a circumferential direction (W) of the journal and in a second direction parallel to a geometric axis of rotation (X) of the crankshaft, in which the method is characterized by comprising: A) during at least one stage of the method, simultaneously projecting a laser beam (2) from a first laser source (1) and a laser beam (2A) from a second laser source (1A) onto said surface area of said second trunnion ( 1002); and B) during at least one further stage of the method, projecting a laser beam (2) from said first laser source (1) onto said surface area of said first trunnion (1001) while simultaneously projecting a beam of laser (2A) from said second laser source (1A) on another portion of a crankshaft.
[0011]
11. METHOD, according to claim 10, characterized in that it comprises: A) during at least one stage of the method: projecting a laser beam (2) from a first laser source (1) onto said surface area of said second trunnion (1002), for the purpose of producing an effective laser spot (5) on said surface area, wherein said effective laser spot (5) extends, in said second direction, along a first portion (P) of the surface area to be hardened, and projecting another laser beam (2A) from a second laser source (1A) onto said surface area of said second trunnion (1002), with the purpose of producing an effective laser spot (5) on said surface area, wherein said effective laser spot (5) extends, in said second direction, along a second portion (PA) of the surface area to be hardened, wherein said first portion (P) and said second portion (PA) extend together over most of said area. surface area to be hardened; B) during at least one other stage of the method: projecting a laser beam (2) from said first laser source (1) onto said surface area of said first trunnion (1001), in order to produce a effective laser spot (5) on said surface area, wherein said effective laser spot (5) extends, in said first direction, over most of the surface area to be hardened; during both said stages of the method, generate a relative movement between the surface of the crankshaft (1000) and the laser source (1) in said circumferential direction, in order to subsequently project the effective laser points (5) onto different portions of said surface areas in the circumferential direction; said effective laser points (5) have a two-dimensional energy distribution.
[0012]
12. METHOD, according to claim 11, characterized in that the first portion (P) is placed adjacent to said second portion (PA), without any overlap between the first and second portions.
[0013]
13. METHOD, according to claim 11, characterized in that the first portion (P) and the second portion (PA) are superimposed on each other.
[0014]
14. METHOD, according to any one of claims 10 to 13, characterized in that, during at least one stage of the method, the laser beam (2) of the first laser source (1) is projected onto a trunnion of a crankshaft ( 1000), and the laser beam (2A) from the second laser source (1A) is projected onto a trunnion of another crankshaft.
[0015]
15. METHOD according to any one of claims 10 to 14, characterized in that, during at least one stage of the process, two journals having the first width are hardened in one step, and a journal having the second width is hardened in a second stage, in which said stages follow one after the other, and without any relative movement between the laser sources and the crankshaft, in the second direction, between said two stages.
[0016]
16. METHOD FOR HARDENING SURFACE AREAS OF AT LEAST TWO CRANKSHAFT (1000), wherein the method is characterized by comprising: during at least one stage of the method, simultaneously using a laser beam (2) from a first laser source (1) and a laser beam (2A) from a second laser source (1A) for hardening a first of said crankshafts; and during at least one further stage of the method, simultaneously using a laser beam (2) from the first laser source (1) for hardening said first of said crankshafts and a laser beam (2A) from the second laser source (1A ) for one-second hardening of said crankshafts.
[0017]
17. METHOD according to claim 16, characterized in that it comprises, during at least one stage of the method, using simultaneously a laser beam (2) from the first laser source (1) and a laser beam (2A) from the second laser source (1A) for hardening the first of said crankshafts, while using a laser beam (2B) from a third laser source (1B) for hardening the second of said crankshafts.
[0018]
18. The method according to any one of claims 1 to 9, 11 to 13 or 16 to 17, characterized in that said surface area comprises at least one sub-area more sensitive to heat and at least one sub-area less sensitive to heat, and in that said energy distribution is adapted so that it is different in a more heat sensitive sub-area than in a less heat-sensitive sub-area, in order to prevent overheating of said more heat-sensitive sub-area.

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法律状态:
2019-08-13| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-03-30| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-05-18| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 11/02/2015, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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EP14382086.8|2014-03-11|

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EP14382086|2014-03-11|

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PCT/EP2015/052879|WO2015135715A1|2014-03-11|2015-02-11|Method and system for laser hardening of a surface of a workpiece|

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