• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a stamping method for the production of a finished or semi-finished metal product of given shape, starting from a slug (51), made of martensitic stainless steel, by a plurality of stamping operations. between molds and / or annealing of the blank until the product is obtained. The process comprises annealing conditioned to obtain a determined work hardening rate, and the cuts to separate the excess material, if necessary, are limited to regions heavily thinned by pre-stamping. In this way, all deformations remain in the plastic field and surface defects due to the intrinsic friability of martensitic stainless steels are avoided. With careful molds, a surface state in the product can be reached with an arithmetic average deviation of roughness R a equal to or less than 0.40 mm. The products thus manufactured can be used as is or with a minimum of termination operations.
    公开号:CH713110A1
    申请号:CH01469/16
    申请日:2016-11-04
    公开日:2018-05-15
    发明作者:Donzé Damien
    申请人:Varin Etampage Sa；
    IPC主号:
    专利说明:

    Description: TECHNICAL FIELD [0001] The present invention relates to a method for the production of metal objects by cold stamping, and the objects thus obtained.
    STATE OF THE ART [0002] Stamping is an implementation method well known in the art for the manufacture of metal objects having a given shape. By this method, a metal piece is obtained from a laminated slab of approximately constant thickness by press stamping between shaped molds. In most cases, the final product is obtained by a plurality of stamping operations with different tools to obtain the desired shape without exceeding the limits of deformability of the chosen material. Annealing and removal operations are generally required.
    This method is widely used, inter alia, in the production of parts for the watch industry, for example the middle, funds, glasses, clasps, or bracelet links, but also jewelry, eyewear , and many other applications. This process can be applied to precious metals, for example gold or platinum, but also to steels, brasses and many other materials. Often, the stamping process results in a semi-finished product, of substantially equal shape, or very close to that of the final product, and intended to undergo finishing and / or finishing operations, such as polishing, precision machining, drilling, metallization, and so on. Advantageously, the stamping allows the production of semi-finished products whose dimensions are very close to the final ones, with an excellent surface state, and without loss of material, so that these semi-finished products require a smaller number of operations. than those obtained, for example, by forging.
    [0004] Stainless steel has become indispensable in many fields: kitchen utensils, everyday objects, medicine, surgery, building and public works, shipbuilding, automotive, aerospace, tools, mechanical industries, food, chemical, transport, etc. . It is fully recyclable and, because of its chrome content, is not very sensitive to corrosion.
    [0005] Several classes of stainless steels are known. Austenitic steels, the most widespread, are characterized by the presence of chromium and nickel and can be easily deformed cold and high temperature. These steels are generally classified in the 300 series of the AISI classification. Among the most used, we can mention the steels AISI 303, AISI 304, AISI304L, AISI316L
    [0006] Austenitic stainless steel lends itself well to stamping work, and it is commonly used in the production of articles such as bodice and trim elements of wristwatches whose material is usually stainless steel type 316L.
    [0007] Martensitic stainless steels, on the other hand, have very high mechanical characteristics and are hardenable. They include chrome steels named AISI 410, AISI 420, AISI 440, and are used because of their superior characteristics of hardness, toughness, elasticity, and load, especially in the production of surgical instruments.
    The stamping of martensitic steels was until now impossible, or not economic, precisely because of their friability during cutting operations and their tendency to crumble (straws) during cold stamping. This results in surface defects that make the post-stamping termination operations very consistent and therefore uneconomical.
    BRIEF SUMMARY OF THE INVENTION [0009] An object of the present invention is to provide a cold stamping method for economically obtaining objects with an irreproachable surface condition, even when applied to stainless steels. martensitic type.
    Another object of the invention is the production of martensitic type stainless steel surgical instruments more economically and efficiently than current means.
    According to the invention, these objects are achieved in particular by means of the object of claim 1, and in particular by a stamping process for the production of a finished or semi-finished metal product of form. data, comprising: preparing a slug, of martensitic stainless steel, a plurality of stamping operations between molds and / or annealing of the blank to obtain the product.
    Preferred variants of the invention are the subject of the dependent claims and may comprise, inter alia: - A decision to perform at least one annealing between two of said stamping operations provided that the rate of work hardening has reached a predetermined value. - A stamping method comprising a first stamping roughing operation producing a blank having a determined profile surrounded by a thin peripheral zone. - A material separation operation in excess of the blank by cutting in correspondence of the thin peripheral zone. - A plurality of stamping operations and / or annealing of the blank to obtain the product. - The stamping of the billet between two molds with protruding regions to create the thin peripheral zone and cavities configured to leave a gap between the molds and the piece. - The positioning of the blank by a hole in the blank in which engages a key in one of the stamping molds. Advantageously, the surface of the hole is larger than the section of the key. - The application of a force in increasing increments separated from release phases. - Annealing steps conditioned to obtain a given value of surface hardness. Research and adaptations have been carried out to anneal the parts being manufactured in passing furnaces.
    BRIEF DESCRIPTION OF THE FIGURES [0013] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:
    Fig. 1 illustrates a blank resulting from the roughing operation:
    Fig. 2 illustrates a roughing operation according to one aspect of the invention. This figure is a section of the blank and molds in the plane A-A shown in FIG. 1;
    Fig. 3 illustrates the product obtained from the sketch of FIG. 2;
    Fig. 4 illustrates a stamping force profile according to one aspect of the invention.
    Example (s) of Embodiment of the Invention [0014] FIGS. 1 and 2 illustrate a roughing operation according to one aspect of the present invention. The stamping process is carried out from a metal billet of suitable shape, generally it is obtained by rolling, with a substantially constant section, but the invention also includes variants in which the initial billet is one obtained by another processes, for example by bar turning or wire cutting, or by any other suitable method. The process of the invention has given excellent results on martensitic type surgical stainless steels, for example the steels of the AISI 420 series commonly used in the production of surgical instruments.
    According to a variant, the method of the invention comprises the production of a blank from the billet of constant thickness. The inventors have found that it is advantageous, in this first step, to use two molds 21, 22 with protruding zones defining the contour of the blank 61. In correspondence with these protruding zones, the metal is greatly thinned by example up to 0.5-0.2 mm thick. Preferably the blank 61 is in front of the cavities 25 of the molds 21,22, so that its thickness is not reduced in this initial passage.
    Following stamping between the molds 21, 22, the blank 61 is separated from the excess material 51 in correspondence of the thin zone 60, for example by cutting or punching.
    The position of the billet 51 in the molds 21, 22 may be provided by a key 35, integral with one of the molds, which engages in a hole 30 of complementary shape, so as to ensure correct positioning. In this case, it is advantageous that the hole 30 has a greater surface than that of the section of the key 35, allow expansion of the material during the strike. In the example shown, the key 35 has a parallelepipedal shape, while the hole 30 has a cross shape: two branches of the cross engage with the key, while the other two branches, empty, leaves a consenting space the expansion of the metal. Other combinations of shapes are possible, however.
    The final product 55 (visible in FIG 3) is obtained by a series of stamping operations with a series of molds, until the desired shape in three dimensions. Punching, drilling or machining steps can also be provided. Unlike the above roughing operation, in which the upper and lower faces of the blank are untouched, the final product generally has curved faces and thickness variations.
    Between the stamping phases which lead to the product 55 annealing operations are generally necessary. The inventors have determined that it is advantageous to carry out these annealing steps provided that the material has reached a minimum degree of hardening during the last stamping step. The rate of work hardening can be determined by any suitable technical process. The work hardening being directly related to the hardening, one can determine or estimate the rate of hardening by a measurement of the surface hardness after each stamping operation, or group of stamping operations, and then compare the value of hardness obtained with a predetermined hardness value, corresponding to the desired work hardening threshold. The hardness can be measured with any conventional method, for example with a standardized Vickers tip, and the value to be achieved depends on the nature of the material and the amount of deformation. In the case of martensitic stainless steel, typical values for Vickers hardness (HV30) are between 120 and 200.
    权利要求:
    Claims (10)
    [1]
    However, one could determine the work hardening by other known means: for example by crystallographic measurements, by microscopic examination, or by simulation with a computer program. When the measurement of work hardening involves the destruction of the workpiece or makes it unusable, it is performed on a small sample of workpieces. When hardening, for example expressed by the surface hardness, remains below the threshold value, the workpiece can be routed directly to the next stamping phase. If, however, the threshold hardness is reached or exceeded, annealing should be carried out before further deformation. The annealing can be carried out in a passage furnace, at a temperature suitable for the material used (between 750 ° C and 900 ° C for martensitic stainless steels) followed by a relatively rapid cooling, the duration of which can be between 5 'and 30', depending on the size and nature of the parts produced. Another aspect of the invention is the application, during the stamping phases, of a deformation force in increasing increments, until the programmed maximum force is obtained, separated by release phases. in which the press is programmed to reduce the deformation force to zero, or to a value substantially less than the maximum force. Fig. 4 illustrates a possible compression profile. The operating parameters of the stamping steps described above, in particular step stamping, the fact of carrying out conditioned annealing to obtain a determined rate of work hardening, and to limit the operations of removal of excess material to heavily thinned regions by prior stamping, allow not to exceed the limits of plastic deformation martensitic stainless steels, and avoid surface defects due to their intrinsic friability. Operating in this way with careful molds, a surface state in the product can be reached with an arithmetic mean difference of roughness Ra equal to or less than 0.40 mm. The semi-finished products thus obtained can be used as is or with a minimum of termination operations. Reference Numbers Employed in Figs. [0025] 21 upper mold 22 lower mold 23 thread 25 cavity 30 alignment hole 35 key 51 piece 55 product 60 thin peripheral area 61 draft
    A stamping method for producing a finished or semi-finished metal product of a given form, comprising: preparing a slug (51) of martensitic stainless steel, a plurality of stamping operations between molds and / or annealing the blank to obtain the product (55).
    [2]
    2. Stamping method according to the preceding claim, comprising a decision to perform at least one annealing between two of said stamping operations provided that the rate of work hardening has reached a predetermined value.
    [3]
    3. Stamping method according to the preceding claim, comprising measuring operations, possibly by sampling, the surface hardness after the stamping operations, and a decision to perform or not annealing provided that the measured surface hardness has reaches a predetermined value.
    [4]
    4. Stamping method according to one of the preceding claims, comprising annealing operations in a passage furnace.
    [5]
    The stamping method according to one of the preceding claims, comprising a stamping roughing operation producing a blank (61) having a defined profile surrounded by a thin peripheral area (60), followed by a separation of metallic material by excess (51) of the blank in section corresponding to the thin peripheral zone.
    [6]
    6. Stamping method according to the preceding claim, wherein the roughing operation comprises the stamping of the billet between two molds (21,22), the molds having projecting regions (23) corresponding to the thin peripheral zone ( 60), and recesses (25) shaped to leave a gap between the molds (21,22) and the billet (51).
    [7]
    7. stamping method according to one of the preceding claims with positioning of the blank with a hole (30) for interacting with a key (35) in one of the stamping molds. The surface of the hole being larger than the section of the key.
    [8]
    8. stamping method according to one of the preceding claims, wherein the force is applied by compression steps, separate release steps in which the applied force is reduced.
    [9]
    9. stamping method according to the preceding claim, wherein the maximum force applied in each compression step is increasing.
    [10]
    10. Stamping method according to one of the preceding claims, wherein the surface condition of the product comprises a roughness with an arithmetic average deviation Ra equal to or less than 0.40 mm.
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    同族专利:
    公开号 | 公开日
    CH713110B1|2020-12-15|
    DE102017103569A1|2018-05-09|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US306849A|1884-10-21|Manufacture of razor-blades |
    US1202611A|1912-11-18|1916-10-24|Herbert Tolputt|Apparatus for making metal articles.|
    US1565340A|1925-05-28|1925-12-15|Treiber Oskar|Manufacturing scissors and the like|
    US2577316A|1949-08-24|1951-12-04|Jr Charles Frederick Ern|Method of manufacturing cutting tools, such as scissors and knives|
    US3164038A|1962-12-12|1965-01-05|Fred E Ahlbin|Method of making scissors|
    US4133107A|1976-07-07|1979-01-09|Donald Eugene Vogel|Tool and method for making the same|
    JP2011245317A|2011-07-01|2011-12-08|Manii Kk|Medical knife|
    法律状态:
    2018-05-31| PK| Correction|Free format text: RECTIFICATION TITULAIRE |
    优先权:
    申请号 | 申请日 | 专利标题
    CH01469/16A|CH713110B1|2016-11-04|2016-11-04|Cold stamping process for the production of a finished or semi-finished metal product of a given shape.|CH01469/16A| CH713110B1|2016-11-04|2016-11-04|Cold stamping process for the production of a finished or semi-finished metal product of a given shape.|
    DE102017103569.9A| DE102017103569A1|2016-11-04|2017-02-22|Forming|
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