• 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 system for controlling the pretensioning of bolts (1), each end of each bolt (1) being screwed into a cavity (4) of two pieces (2) to be joined. Each bolt (1) comprises a pretensioning piece (3) comprising a double wedge (5), a washer (6) disposed at each side of the double wedge (5), and attachment elements that attach the wedges once the desired preload has been reached. The pretensioning of the corresponding bolt (1) is carried out using a tensioning tool (10) that acts on the pretensioning piece (3), reducing the distance between the wedges, increasing the distance between the pieces (2) to be joined, and reducing the distance between the ends of the wedges and the washers (6). In the control system of the invention, at least one of the described distances is measured, the tensioning tool acting according to the measured distance.
    公开号:ES2775069A2
    申请号:ES202090027
    申请日:2017-12-27
    公开日:2020-07-23
    发明作者:Lesmes Javier Montreal；Escartin Javier Callen；Eleta Javier Iriarte；Pascual Eneko Sanz
    申请人:Nabrawind Technologies SL；
    IPC主号:
    专利说明:

    [0004] Field of the invention
    [0006] The present invention relates to a bolt prestressing control system.
    [0008] Background
    [0010] Bolts are one of the most common methods of joining two or more components. In most applications, it is extremely important that tightening is done evenly to the proper level of tension on the bolt, and this requires the use of proper tools and control equipment.
    [0012] There are different tensioning techniques that can be classified according to the control of the tightening in the element being pretensioned. The pretension can be measured on a single screw or on a plurality of bolts.
    [0014] Depending on the control technique used, the following methods shown in Figures 1a and 1b of the state of the art differ:
    [0015] - Torque control. During the torque of the bolt or nut, the torque is measured by monitoring the tightening tension. It is also combined with the measurement of the angle of rotation.
    [0016] - Control of the “yield” stretch. When the point between the elastic zone and the plastic zone is reached.
    [0017] - Control of the axial load. Lengthening the screw prior to tightening the nut. - Control of stretching by heating and expanding the screw and / or the nut or the parts to be joined prior to tightening.
    [0019] However, if the bolt to be tensioned and the bolt to be controlled have limited accessibility, none of the previously mentioned control methods would be applicable.
    [0021] In the state of the art, there are tightening tensioning tools for screws that they have specific controls. Such is the case of the utility model ES1072452U whose tightening tip rotates and produces the relative displacement of the elements to be tightened, reducing the distance between two retainers until the contact between them causes the rotation to be interrupted. In this case, the retainers can also be replaced by contact sensors. Patent applications ES2220182A1 and ES2277506A1 use as means of measurement and control a load sensor that reports the force applied in the constriction of the elements to be joined and a clamping force measuring system based on strain gauges and a distance meter traversed by the tool's fingers by means of a magnetic displacement sensor.
    [0023] Likewise, document WO2017174828A1 describes how two pieces or modules are joined through bolts that are pretensioned with a tensioning tool. The ends of each bolt are threaded and are housed and threaded in a respective cavity of the pieces to be joined. The bolt comprises a pretensioning piece in the form of a double wedge for prestressing the bolt. On each side of the double wedge there is a washer that rests on said double wedge through a respective inclined face. The pretensioning piece also comprises fastening elements. By applying the external load, the distance between the wedges of the double wedge is reduced, increasing the distance between the pieces to be joined and reducing the distance between the ends of the wedges and the washers, producing the preload or tensioning of the bolt.
    [0025] Description
    [0027] The object of the invention is to provide a bolt prestressing control system, as defined in the claims.
    [0029] In the control system of the invention, each end of each bolt is threaded into a respective two-piece cavity to be joined together. Each bolt in turn comprises a pretension piece for prestressing said bolt. Said pretensioning piece comprises a double wedge formed by two wedges that hug the bolt, a washer arranged on each side of the double wedge that rests on said double wedge through a respective inclined face, and fixing elements that fix the wedges of the double wedge once the desired preload is reached. The prestressing of the corresponding bolt is carried out by means of a tensioning tool that acts on the pretensioning piece, reducing the distance between wedges of the double wedge, increasing the distance between the pieces to be joined for their prestressing, and reducing the distance between the ends of the wedges and the washers.
    [0031] However, in the control system of the invention at least one of said distances described and that vary during tightening of the bolt is measured, said tensioning tool acting as a function of said measured distance.
    [0033] As mentioned, the two ends of the bolt to be tensioned are threaded in the cavities that are housed inside the elements to be joined and are not accessible. For this reason, neither the tightening nor the angle of rotation can be controlled according to the methods described in the previous section referring to the state of the art. Nor can the “yield” stretch be controlled, since for this the angle of rotation and the tightening torque would have to be previously measured. Furthermore, if a plurality of bolts were arranged parallel to and close to each other, lateral accessibility to the bolts would also be limited.
    [0035] Therefore, with the control system of the invention the correct tensioning of the bolts is possible even if access to said bolts is limited or difficult, preventing the bolt in question from being deformed excessively and being plastically deformed.
    [0037] Brief description of the drawings
    [0039] Next, a series of drawings will be described very briefly that help to better understand the invention and that expressly relate to an embodiment of said invention that is presented as a non-limiting example thereof.
    [0041] Figures 1a and 1b show the tension control techniques existing in the state of the art.
    [0043] Figure 2a shows the arrangement of the bolts along the modular blade and Figure 2b shows the same bolts with their pretensioning pieces placed on them.
    [0045] Figure 3a shows a section of the blade joint with a single pretensioning part and Figure 3b the pretensioning part and its inner bolt taken in a section through its longitudinal axis.
    [0046] Figures 4a and 4b represent two practical embodiments of tightening the joining elements of the pretensioning piece.
    [0048] Figure 5 represents a practical embodiment for the configuration of the tensioning tool.
    [0050] Figure 6 represents a graph of the load acquired by the bolt as a function of the displacement suffered.
    [0052] Figure 7 represents a specific configuration of a hydraulic tensioning tool.
    [0054] Detailed description
    [0056] As shown in figure 2a, the elements 2 to be joined in this case are two halves of a modular blade that, when joined, will form the blade of a wind turbine for example. The union of the two halves is carried out through a plurality of bolts 1, as can be seen in said figure. The use of said bolts to join a modular blade is described for example in WO2017174828A1.
    [0058] In the preferred embodiment of the invention, each end of the bolt 1 is threaded in a respective cavity 4 of the two pieces 2 to be joined together, as can be seen, for example, in Figures 3a or 3b. The bolt 1 in turn comprises a pretension piece 3 for prestressing said bolt 1. Said pretension piece 3 comprises a double wedge 5 formed by two wedges that hug the bolt 1, a washer 6 arranged on each side of the double wedge 5 that rests on said double wedge 5 through a respective inclined face, and fixing elements 8 that fix the wedges of double wedge 5 once the desired preload is reached. The prestressing of the corresponding bolt 1 is carried out by means of a tensioning tool 10 that acts on the pretensioning piece 3, reducing the distance "a" between wedges of the double wedge 5, increasing the distance "b" between the pieces 2 to be joined. pretensioning the corresponding bolt 1, and reducing the distance “c” between the ends of the wedges and the washers 6.
    [0060] However, in the control system of the invention at least one of said distances "a", "b" or "c" described and which vary during the tightening or tensioning of the bolt 1 is measured, said tensioning tool 10 acting as a function of said distance "a", "b" or "c" measured.
    [0062] Figure 2b shows the plurality of bolts 1 of figure 2a but with the pretensioning pieces 3 arranged on them, hugging them. The protruding end of the bolt 1 shown in figure 2b will be threaded into the blade piece to be joined and will not be visible.
    [0064] To facilitate the joining of the bolts 1 to the pieces 2 to be joined, the two halves of the modular blade in this example, inserts 7 are arranged in the cavities 4 of said blades 2. The interior of said inserts 7 are threaded in a manner that the threaded end of each bolt 1 is housed in a corresponding insert 7.
    [0066] In figure 3a a single bolt 1 is represented with the two ends threaded in the inserts 7 that are inside the blade 2 and as it is also covered with the pretensioning piece 3, said bolt 1 remains totally inaccessible. In reality, as shown in figure 2a, they are a plurality of bolts 1 whose ends are threaded into the inserts 7 of the cavities 4, and furthermore, the pretension pieces 3 cover the bolts 1, which makes it impossible to control of its stretch and / or axial load.
    [0068] Therefore, with the control system of the invention the correct tensioning of the bolts 1 is possible even though access to said bolts 1 is inaccessible, preventing the bolt 1 in question from being deformed excessively and being plastically deformed.
    [0070] As shown in figure 3b, when the tensioning of one of the bolts 1 is carried out, the control parameters are obtained in the pretension piece 3, by means of the displacement of the parts that compose it: the double wedge 5 that is it moves on the washers 6 with inclined faces pushed by the tensioning tool 10 that applies a force on said double wedge 5.
    [0072] By applying said clamping force on the double wedge 5, the movement between said wedge 5 and the washers 6 is made possible, which leads to stretching the corresponding bolt 1.
    [0074] The tensioning tool 10 according to the preferred embodiment of the invention, in addition to providing the necessary force to cause the corresponding bolt 1 to stretch, also carries out the measurement of at least one of the distances "a", "b" or "c" described, Therefore, the control over the deformation suffered by bolt 1 during prestressing or tightening is total and immediate, which ensures the correct pretensioning of bolt 1, preventing bolt 1 from being deformed excessively, that is, it can deform plastically.
    [0076] As already explained, the displacements that occur during the tensioning of a bolt 1 are three and at least one of them should be controlled:
    [0078] - Displacement a (represented by the dimension "a" in figure 3b) .- Approximation between two wedges 5 when an external force is applied.
    [0080] - Displacement b (represented by dimension "b" in figure 3b) .- Increase in the distance between the inserts 7 where the threaded ends of the bolt are housed, that is, increase the distance between the pieces 2 to be joined.
    [0082] - Displacement c (represented by the dimension "c" in figure 3b) .- Reduction of the relative distance between the ends of the wedges 5 and washers 6 along the sliding plane or the direction of the applied force.
    [0084] As mentioned, the two wedges of the double wedge 5 of the pretensioning piece 3 cooperate with the inclined faces of the washers 6 arranged at each end of the pretensioning piece 3. In this way, when the two wedges approach 5 towards each other the distance "a" represented in figure 3b is shortened, and the corresponding washers 6 are pushed away from one another, pushed by said wedges, increasing the distance "b" represented in figure 3b. In this way, the parts to be joined through the bolts 1, in the practical embodiment of the invention, the two halves of a blade 2, tend to separate so that the bolt 1 is stretched, obtaining the desired prestress as a function of said stretched.
    [0086] In the control system of the invention, the distance "a" is preferably measured, through the tensioning tool 10 which in turn applies the necessary force that causes the corresponding bolt 1 to stretch or pretensioning, to control the stretching of said bolt. 1, as will be described in detail later.
    [0088] The control system of the invention is carried out in three phases, shown in figure 6 where the phases of deformation or elongation of bolt 1 during operation are shown. prestressing:
    [0090] Phase 1: non-linear pre-tightening phase.
    [0091] Phase 2: deformation of bolt 1 until reaching an intermediate target preload. Phase 3: deformation of bolt 1 and torque control until final preload.
    [0093] The wedges of the double wedge 5 are joined together by means of the fixing elements 8, preferably screws, as shown for example in figure 3a, with the possibility of relative movement between both wedges.
    [0095] In a non-limiting example, when rotating the fixing elements 8 in one direction the two wedges of the double wedge 5 will approach each other guided by said fixing elements 8, and when rotating in the opposite direction both wedges will move one of the other.
    [0097] Figure 4a shows how tensioning can be done sequentially on all the fixing elements 8 or simultaneously, figure 4b, with a complement 9 of pinions that acts on all the fixing elements 8 of the pretensioning piece (3).
    [0099] In the example of figures 2a and 2b, where the union of the two blades 2 is made through a plurality of bolts 1, said bolts 1 are pre-tensioned, for example measuring the distance "a" between wedges of each double wedge 5 in a preliminary positioning phase that is carried out with a tool, not shown in the drawings, which places the tensioning tools 10 of all the bolts 1 in the same starting position.
    [0101] There are two practical embodiments for the configuration of the tensioning tool: hydraulic actuators or electric actuators.
    [0103] In the case of using hydraulic actuators, these act simultaneously on both wedges of the double wedge 5, as shown in figure 5. The lower and upper wedge advance simultaneously to approach in a coordinated manner.
    [0105] In the case of using electric actuators, the fixing elements can be carried out independently or jointly. The steps in the case of an electric tool are as follows: 1st force control, 2nd and 3rd movement control with electric assistance.
    [0106] Figure 6 shows the three tightening zones described above. the non-linear phase at the beginning that is solved with a positioning tool, the phase of control of the deformation of bolt 1 with hydraulic or electrical actuation and the third phase that is a control of the deformation of bolt 1 with application of the tightening torque (manually or electrically) to reduce the distance between the wedges of the double wedge 5.
    [0108] In the preferred embodiment of the tensioning tool 10 it is hydraulic. As shown in Figure 7, said tensioning tool 10 comprises a hydraulic cylinder, preferably single-acting, comprising a piston that acts on the upper part of the pretensioning piece 3, that is, on the upper wedge. The cylinder body, that is to say the casing, is connected via an interface plate 12 and temporarily arranged connecting elements 13 to the lower wedge of the pretensioning piece 3. As the hydraulic cylinder piston advances, the wedge The upper one descends, pushed by the plunger, and the interface plate 12 rises, dragging the lower wedge in a coordinated manner. The reduction of the distance "a" between the two wedges of the double wedge 5 is measured with a dial gauge 14 that is held integral with one of the wedges of the double wedge 5, preferably the upper wedge, through the interface plate 12, and whose measuring tip is in contact with the lower wedge.
    [0110] Once the desired stretching or prestressing of the corresponding bolt 1 has been carried out, the connecting elements 13 are disassembled by removing the corresponding tensioning tool 10. Although it is not necessary to fix the wedges of the double wedge 5 together again (since after the prestressing operation the set formed by the double wedge 5, the washers 6 and the pieces 2 to be joined is very stable), optionally they could be place fixing elements 8, for example screws, permanently.
    权利要求:
    Claims (9)
    [1]
    1. Bolt prestressing control system (1), each end of each bolt (1) being threaded in a respective cavity (4) of two pieces (2) to be joined together, the bolt (1) comprising a piece of pretension (3) for prestressing said bolt (1), the pretension part (3) comprising a double wedge (5) formed by two wedges that hug the bolt (1), a washer (6) on each side of the double wedge (5) that rests on said double wedge (5) through a respective inclined face, and fixing elements (8,) that fix the wedges of the double wedge (5) once the desired preload has been reached, taking The prestressing is carried out by means of a tensioning tool (10) that acts on the pretensioning part (3), reducing the distance (a) between wedges of the double wedge (5), increasing the distance (b) between the parts (2) to join for its prestressing, and the distance (c) between the ends of the wedges and the washers (6) is reduced, characterized in that the control system measures at least one of the distances (a, b, c) that varies during the tightening of the bolt (1), said tensioning tool (10) acting as a function of said distance (a, b, c) measured.
    [2]
    2. Control system according to claim 1, wherein it is the tensioning tool (10) itself that carries out the measurement of the at least one distance (a, b, c) during tightening.
    [3]
    Control system according to claim 1 or 2, wherein the prestressing of the bolt (1) is carried out in three phases, wherein the first phase is a non-linear pre-tightening phase, the second is a phase of deformation of the bolt (1) until reaching an intermediate target preload, and the third is a phase of deformation of the bolt (1) and torque control until the final preload.
    [4]
    Control system according to any of the preceding claims, wherein the tensioning of the bolt (1) is carried out sequentially on the tightening elements (8).
    [5]
    Control system according to any of claims 1 to 3, wherein the tensioning of the bolt (1) is carried out simultaneously on all the elements tightening (8) by means of a complement (9) that acts on all tightening elements (8).
    [6]
    Control system according to any of the preceding claims, wherein a plurality of bolts (1) are pre-tensioned, the distance (a) between wedges of each double wedge (5) being measured in a preliminary positioning phase carried out with a tool that places the tensioning tools (10) of all the bolts (1) in the same starting position.
    [7]
    Control system according to any of the preceding claims, wherein the tensioning tool (10) is a hydraulic or electric tool.
    [8]
    8. Control system according to claim 7, wherein the tensioning tool (10) is a hydraulic cylinder, preferably single-acting, comprising a plunger that acts on the upper wedge of the double wedge (5) of the pretensioning piece (3), the lower wedge of the double wedge (5) being connected with an interface plate (12) included in the hydraulic cylinder (10), through some connecting elements (13) so that when the piston of the cylinder (10) the upper wedge descends pushed by the piston and the lower wedge rises dragged by the interface plate (12) which moves integral with the casing of the hydraulic cylinder (10).
    [9]
    Control system according to any of the claims, wherein the distance (a) between wedges is obtained by means of a dial gauge (14) that is held together with one of the wedges of the double wedge (5) and whose measuring tip is rests on the other wedge of said double wedge (5).
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    同族专利:
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    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    PCT/ES2017/070853|WO2019129894A1|2017-12-27|2017-12-27|System for controlling bolt pretensioning|
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