Stretcher device, control method for stretcher device and control program

Abstract

To appropriately manage deformation amount of a workpiece.SOLUTION: A stretcher device 1 comprises: a first clamp portion 3F gripping one end of a workpiece W; a second clamp portion 3M gripping the other end of the workpiece W; an actuator 6 that moves the second clamp portion 3M in a direction away from the first clamp portion 3F to increase a distance between the first clamp portion 3F and the second clamp portion 3M; a laser sensor 34 that measures the distance D between the first clamp portion 3F and the second clamp portion 3M; and a control unit 74 that drives the actuator 6 on the basis of the distance D measured by the laser sensor 34.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a stretcher device, a control method for a stretcher device, and a control program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a stretcher device that applies a tensile stress equal to or greater than the yield point (proof strength) to a plate-shaped workpiece made of steel, aluminum, or the like, and removes residual stress (see, for example, Patent Document 1). In this type of stretcher device, the hydraulic cylinder, which is an actuator, is servo-controlled, and the amount of strain (deformation) of the workpiece is managed based on the extension of its stroke. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 60-82220 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are many error factors between the actuator stroke and the deformation of the workpiece, such as distortion of the hydraulic cylinder, stretch of the link, deformation of the frame, etc. Therefore, even if you try to pull the workpiece 50 mm with the cylinder stroke, it may happen that the workpiece actually extends only 45 mm.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to appropriately manage the deformation amount of a workpiece. [Means for solving the problem]

[0006] The present invention relates to a stretcher device, A first gripping portion that grips one end of the workpiece; A second gripping portion that grips the other end of the workpiece; a drive unit that moves the second gripping portion in a direction away from the first gripping portion to extend a distance between the first gripping portion and the second gripping portion; A measuring unit that measures the distance between the first gripping unit and the second gripping unit; A control unit that drives the drive unit based on the distance measured by the measurement unit; Equipped with. Effect of the Invention

[0007] According to the present invention, residual stress in a workpiece can be suitably removed. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are a plan view and a side view of a stretcher device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the stretcher device taken along line II-II in FIG. [Diagram 3] 4 is a flowchart showing a procedure of a stress relief process according to the embodiment. [Figure 4] 1A to 1C are diagrams for explaining the state of a workpiece in a stress relief process according to an embodiment. [Diagram 5] FIG. 13 is a diagram showing an example of a display of operating points on a stress-strain diagram in a stress relief process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0010] [Overall configuration of stretcher device] 1(a) and (b) are a plan view and a side view of a stretcher device 1 according to this embodiment, and FIG. 2 is a cross-sectional view of the stretcher device 1 taken along line II-II in FIG. 1 and 2, the stretcher device 1 according to this embodiment is a device that removes residual stress and removes distortion by applying a tensile stress equal to or greater than the yield point to a plate-shaped workpiece (object to be processed) W. The material of the workpiece W is not particularly limited, but may be, for example, steel material or aluminum. In the following description, the X, Y, and Z directions refer to the directions shown in FIGS.

[0011] Specifically, the stretcher device 1 includes a frame 2, two clamp units 3, a position adjustment mechanism 5, an actuator 6, and a control device 7.

[0012] The frame 2 is a support member having a generally rectangular shape that is elongated in the X direction. The frame 2 has side walls 21 that are erected along the X direction on both sides in the Y direction.

[0013] The two clamp units 3 are arranged side by side in the X direction on the frame 2, and pull the workpiece W in the X direction while clamping the workpiece W between them. The two clamp units 3 are disposed on the side wall 21 of the frame 2, and are supported so as to be able to move individually in the X direction using the side wall 21 as a rail. Of the two clamp units 3, the first clamp unit 3F on one side in the X direction (the left side in Fig. 1) is the clamp on the side that is fixed to the frame 2 by the position adjustment mechanism 5 (hereinafter referred to as the "fixed side"). The second clamp unit 3M on the other side in the X direction (the right side in Fig. 1) is the clamp on the side that moves away from the first clamp unit 3F by the actuator 6 to pull the workpiece W (hereinafter referred to as the "pulling side"). The two clamping parts 3 have a plurality of chuck jaws 32 arranged side by side along the Y direction on the side surfaces facing each other in the X direction. Each of the chuck jaws 32 is capable of firmly gripping the workpiece W.

[0014] At least one of the two clamp units 3 is provided with a laser sensor 34 that measures the distance D between them along the X direction. In this embodiment, for example, the laser sensor 34 is disposed in the first clamp unit 3F, and its target 35 is disposed in the second clamp unit 3M. Two sets of laser sensors 34 and targets 35 are provided on both side surfaces of the two clamp parts 3 in the Y direction. The laser sensor 34 and the target 35 are disposed on the side surface of each clamping part 3 as close as possible to the gripped portion of the workpiece W to be measured, and also as close as possible to each other. Specifically, the laser sensor 34 and the target 35 are disposed on the side surface of each clamping part 3 immediately above the tip of the chuck jaws 32. The laser sensor 34 and the target 35 may be any one that can detect the "amount of change (amount of change from a reference length)" of the distance D between the two clamping parts 3. Furthermore, the measuring means for measuring the distance D is not particularly limited to any other specific configuration as long as it can measure the distance D with the required accuracy and at a position close to the workpiece W. For example, the clamping part 3 itself may be the measurement target of the laser sensor instead of the target, a distance measuring sensor other than a laser sensor may be used, or a potentiometer or the like may be used.

[0015] The position adjustment mechanism 5 holds (fixes) the fixed-side first clamp portion 3F so that its position in the X direction is adjustable. The position adjustment mechanism 5 of this embodiment is a ball screw or a trapezoidal screw, etc., and includes a nut portion 51, a screw shaft 52, and a drive motor (gear motor) 53. The nut portion 51 is fixed to the lower surface of the first clamp portion 3F. The screw shaft 52 extends along the X direction below the first clamp portion 3F in a state where it is screwed into the nut portion 51. The drive motor 53 rotates the screw shaft 52 by driving. With this configuration, the position adjustment mechanism 5 rotates the screw shaft 52 about its central axis by being driven by the drive motor 53, and moves the first clamp portion 3F fixed to the nut portion 51 in the X direction.

[0016] The actuator 6 is a drive unit that moves the second clamp unit 3M on the pulling side in the X direction to extend the distance D between the two clamp units 3. The actuator 6 in this embodiment is, although not limited to, a hydraulic cylinder. Specifically, the actuator 6 is disposed on the other side in the X direction (the right side in FIG. 1) of the second clamp portion 3M and is fixed to the frame 2, and causes a cylinder rod 6a to extend and retract to the other side. The tip of the cylinder rod 6a is fixed to a block body 62 supported by the frame 2 so as to be movable in the X direction. The block body 62 is connected to the second clamp portion 3M via two link arms 63 disposed on both sides of the block body 62 in the Y direction. With this configuration, when the actuator 6 is driven to extend the cylinder rod 6a to the other side in the X direction, the second clamp portion 3M connected to the block body 62 via the link arm 63 moves to the other side in the X direction.

[0017] The control device 7 includes a display unit 72 , a storage unit 73 , and a control unit 74 . The display unit 72 is, for example, a liquid crystal display, an organic electroluminescence display, or other display, and displays various information based on a display signal input from the control unit 74. The display unit 72 may be a touch panel that also serves as part of the operation unit, or may include a speaker capable of audio display (output). The storage unit 73 is a memory configured, for example, by a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores various programs and data, and also functions as a work area for the control unit 74. In the storage unit 73 of this embodiment, stress-strain curve data (σ-ε data) 731 of the material of the workpiece W is stored in advance. The control unit 74 is configured with, for example, a CPU (Central Processing Unit) and controls each part of the stretcher device 1. Specifically, the control unit 74 controls the driving of the drive motor 53 of the position adjustment mechanism 5 and the actuator 6, etc., based on a user operation from an input unit (not shown) or a predetermined program.

[0018] [Stretcher device in operation] Next, the stress relief process for the workpiece W by the stretcher device 1 will be described. FIG. 3 is a flowchart showing the steps of the stress relief process, FIG. 4 is a diagram for explaining the state of the workpiece W during the stress relief process, and FIG. 5 is a diagram showing an example of the display of the operating point on a stress-strain diagram during the stress relief process.

[0019] In the stress relief process, residual stress is removed and distortion is eliminated by applying a tensile stress equal to or greater than the yield point to the workpiece W. This stress relief process is executed by the control unit 74 of the control device 7 reading and developing a corresponding execution program from the storage unit 73 based on, for example, a user operation. In the following, unless otherwise specified, "stress" refers to tensile stress in the X direction, and "strain" refers to longitudinal strain in the X direction.

[0020] 3, in the stress relief process, the user first puts the workpiece W into the stretcher device 1 (step S1). Specifically, the workpiece W is inserted between the two clamp units 3 from the Y direction by a roller conveyor (not shown). Then, the user grips both ends of the workpiece W in the X direction with the chuck jaws 32 of the two clamp units 3 (step S2).

[0021] Next, a preliminary (pre-production) first tension control is performed to eliminate the initial deflection (step S3). 4(a), a pre-operational pulling operation is performed to minimize the vertical deflection δ in the pulling direction (X direction) of the workpiece W and the gap (play) in the drive system. Here, the "drive system" includes the actuator 6, which is the drive source, as well as connecting elements (position adjustment mechanism 5, block body 62, link arm 63, etc.) that determine the X-directional positions of the two clamp parts 3 that apply tension to the workpiece W. More specifically, the control unit 74 drives the actuator 6 to apply tension to the workpiece W little by little. Then, as shown in FIG. 4(b), the second clamp unit 3M moves in the X direction by ΔX, so that the warped workpiece W becomes as straight as possible along the X direction, and the play in the drive system becomes substantially zero. In this case, the control unit 74 may determine the state of warping of the workpiece W based on the distance D between the two clamp units 3 and the output of the actuator 6 (or the stress and strain generated in the workpiece W). In other words, it may be determined that the warping has been eliminated when the amount of change in the deformation amount (distance D) of the workpiece W relative to an increase in the output of the actuator 6 becomes equal to or less than a predetermined amount. The state of the tensile stress and longitudinal strain in the X direction generated in the workpiece W at this time becomes the initial state of the actual second tension control in the next step (initial position P1 in the stress-strain diagram (see Figure 5)). As a result, in the actual second tension control in the next step, the tensile force in the X direction immediately acts on the workpiece W.

[0022] In step S3, the stress of the workpiece W at the initial position P1 may be set to a predetermined initial stress σ0 that has just started to be generated, rather than to zero or less (see FIG. 5). This allows the initial stress σ0 to be common regardless of the cross-sectional shape (cross-sectional area) of the workpiece W, and suppresses variation in the initial state in the next step. In this case, the initial stress σ0 of the workpiece W is expressed by the following equation (1) using the thickness t of the workpiece W in the vertical direction, the width B in the Y direction, and the output (axial load) F of the actuator 6. σ0 = F / (t × B) (1) Therefore, σ0 is preset to a predetermined low stress value, and when the cross-sectional shape of the workpiece W changes, the output F of the actuator 6 is calculated using the above formula (1). This makes it possible to keep the initial stress σ0 for the next step constant even if the cross-sectional shape of the workpiece W changes. In this step, a stress-strain diagram may be displayed on the display unit 72, as in the next step.

[0023] Next, the actual second tensile control is performed to remove the stress (step S4). In this step, as shown in Fig. 4(c), the distance D between the two clamp units 3 is further extended (widened) from the state in step S3, thereby elongating the workpiece W in the X direction. Specifically, the control unit 74 drives the actuator 6 to apply tension to the workpiece W until the stress-strain state of the workpiece W shifts from the initial position P1 to a predetermined end position P2 on the stress-strain diagram, as shown in Fig. 5. The end position P2 is preset at a predetermined position between the 0.2% proof stress (yield point) Py and the maximum stress point Pmax based on the stress-strain curve data 731 of the material of the workpiece W. At this time, the end position P2 is set at a point with a sufficient margin from the maximum stress point Pmax so that the workpiece W does not break. When the strain generated in the workpiece W reaches the strain value of the end position P2, the control unit 74 stops the actuator 6 and ends the second tension control. The strain can be obtained by dividing the elongation (stroke) ΔL of the workpiece W in the X direction by the initial length L of the workpiece W in the X direction. The initial length L is preset, and the elongation ΔL is measured by the laser sensor 34 (and the target 35).

[0024] 5, the control unit 74 obtains the current position (operating point P) on the stress-strain diagram in real time and displays it on the display unit 72. Specifically, the control unit 74 reads out the stress-strain diagram data 731 from the storage unit 73, and sets the point on the stress-strain diagram data 731 corresponding to the strain calculated from the distance D as the operating point P. Alternatively, the control unit 74 may use the stress calculated from the output of the actuator 6 and set the point of the calculated strain and stress as the operating point P. This allows the user to easily recognize the current stress-strain state of the workpiece W. However, this display mode does not have to be the operating point on the stress-strain diagram. For example, the elongation ΔL may be displayed instead of the strain, or the output of the actuator 6 may be displayed instead of the stress. Alternatively, each value may be displayed as a waveform or a digital value instead of a stress (force)-strain (elongation) diagram.

[0025] The end position P2 at which the second tension control is ended may be detected by stress instead of strain, or both may be used. Using both improves the accuracy of managing the operating point, and the second tension control can be stopped at the end position P2 with higher accuracy. As a result, breakage of the workpiece W can be more reliably suppressed. Alternatively (or in addition to) monitoring the stress and strain, the load rise rate may be monitored in real time. The load rise rate is the rate of change of stress per unit strain, and corresponds to the slope of the stress-strain diagram. This load increase rate is monitored, and when it becomes equal to or lower than a predetermined threshold, the second tension control is stopped. This makes it possible to prevent the workpiece W from entering the slow speed region just before breakage (after the maximum stress point Pmax) in the stress-strain diagram. As a result, breakage of the workpiece W can be more reliably suppressed.

[0026] As shown in FIG. 3, when the second tension control in step S4 is completed, the user releases the grip of the workpiece W by the chuck jaws 32 of the two clamp units 3 (step S5). Then, the user carries the workpiece W out of the stretcher device 1, for example, by a roller conveyor (not shown) (step S5). This completes the stress relief process by the stretcher device 1.

[0027] [Technical Effects of the Embodiments] As described above, according to this embodiment, the distance D between the first clamp portion 3F and the second clamp portion 3M is measured, and the actuator 6 is driven based on this distance D. This makes it possible to manage the amount of deformation of the workpiece W with higher accuracy than in the past, where the amount of deformation of the workpiece was managed by the stroke of the actuator (cylinder). In other words, the amount of deformation in the X direction of each part, such as the first clamp part 3F, the second clamp part 3M, the screw shaft 52 of the position adjustment mechanism 5, the link arm 63, and the frame 2, affect the extension of the cylinder rod 6a of the actuator 6 and the extension of the workpiece W as error factors. In this regard, in this embodiment, the distance D between the two clamp parts 3 that grip the workpiece W is directly measured and the drive of the actuator 6 is controlled based on this, so that the above error factors can be eliminated. Therefore, the amount of deformation of the workpiece W can be appropriately managed.

[0028] In addition, according to this embodiment, the strain generated in the workpiece W is calculated based on the actual measured value of the distance D, and the operating point P on the stress-strain curve data 731 is displayed on the display unit 72 based on the calculated strain. This allows the user to easily recognize the current stress-strain state of the workpiece W.

[0029] Furthermore, according to this embodiment, the stress generated in the workpiece W is calculated based on the output of the actuator 6, and the driving of the actuator 6 is stopped based on the calculated stress. This makes it possible to stop driving the actuator 6 based on the stress in addition to controlling the actuator 6 based on the strain. Therefore, breakage of the workpiece W can be more reliably prevented.

[0030] Furthermore, according to this embodiment, the rate of change in stress per unit strain generated in the workpiece W is calculated as the load increase rate, and the driving of the actuator 6 is stopped based on this load increase rate. This makes it possible to prevent the workpiece W from entering the slow-speed region (after the maximum stress point Pmax) just before fracture in the stress-strain diagram, and thus makes it possible to more reliably suppress fracture of the workpiece W.

[0031] Furthermore, according to this embodiment, in the first tension control before the actual operation to reduce the initial deflection of the workpiece W, the output of the actuator 6 is adjusted according to the cross-sectional shape of the workpiece W so as to generate a predetermined initial stress σ0 in the workpiece W. This allows the initial stress σ0 to be standardized regardless of the cross-sectional shape (cross-sectional area) of the workpiece W, thereby suppressing variation in the initial state in the actual second tension control.

[0032] [others] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the actuator 6 (hydraulic cylinder) of the drive system can be controlled with a hydraulic servo valve circuit to accurately control the speed and stop position. Also, the electric motor that drives the hydraulic pump for the hydraulic cylinder may be an inverter motor or servo motor whose rotation speed can be controlled. Alternatively, the actuator of the drive system may be electrically driven instead of hydraulically driven. For example, a mechanical servo mechanism such as a tension type using a ball screw and a servo motor or a link drive type may be used.

[0033] In addition, the details shown in the above embodiment can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0034] 1. Stretcher device 2 Frames 3 Clamp section 3F First clamp part (first grip part) 3M Second clamp part (second grip part) 5 Position adjustment mechanism 6 Actuator (drive unit) 6a Cylinder rod 7 Control device 21 Side wall 32 Chuck jaws 34 Laser sensor (measurement section) 35 Target (measurement section) 51 Nut part 52 Screw shaft 53 Drive motor 62 Block Letters 63 Link arm (connection part) 72 Display section 73 Memory section 74 Control unit (calculation unit) 731 Stress-strain curve data D Distance (distance between two clamp parts) F Output P operating point P1 initial position P2 End position Pmax Maximum stress point Double work σ0 Initial stress

Claims

1. A first gripping portion that grips one end of the workpiece; A second gripping portion that grips the other end of the workpiece; a drive unit that moves the second gripping portion in a direction away from the first gripping portion to extend a distance between the first gripping portion and the second gripping portion; A measuring unit that measures the distance between the first gripping unit and the second gripping unit; A control unit that drives the drive unit based on the distance measured by the measurement unit; A stretcher apparatus comprising:

2. A frame supporting the first gripping portion and the driving portion; A connecting portion that connects the second gripping portion and the driving portion; Equipped with 2. The stretcher apparatus of claim 1.

3. The measurement unit is a laser sensor or a potentiometer.

2. The stretcher apparatus of claim 1.

4. A storage unit that stores stress-strain curve data of the material of the workpiece in advance; A calculation unit that calculates a strain generated in the workpiece based on an actual measurement value of the distance measured by the measurement unit; A display unit that displays an operating point on the stress-strain curve data based on the strain of the workpiece calculated by the calculation unit; Equipped with 2. The stretcher apparatus of claim 1.

5. The control unit is Calculating a stress generated in the workpiece based on an output of the drive unit; stopping the driving of the driving unit based on the stress; 2. The stretcher apparatus of claim 1.

6. The control unit is Calculating the rate of change of stress per unit strain generated in the workpiece; stopping the driving of the driving unit based on the rate of change; 2. The stretcher apparatus of claim 1.

7. The control unit is Executing a first control for reducing an initial deflection of the workpiece and a second control for generating a predetermined stress in the workpiece after execution of the first control; In the first control, an output of the driving unit is adjusted in accordance with a cross-sectional shape of the workpiece so as to generate a predetermined initial stress in the workpiece.

2. The stretcher apparatus of claim 1.

8. A control method for a stretcher device including a first gripping unit that grips one end of a workpiece, a second gripping unit that grips the other end of the workpiece, a drive unit that extends a distance between the first gripping unit and the second gripping unit, and a measurement unit that measures the distance between the first gripping unit and the second gripping unit, The measuring unit measures a distance between the first gripping portion and the second gripping portion; Driving the driving unit based on the distance measured by the measuring unit. A method for controlling a stretcher device.

9. A control program for a stretcher device including a first gripping unit that grips one end of a workpiece, a second gripping unit that grips the other end of the workpiece, a drive unit that extends a distance between the first gripping unit and the second gripping unit, and a measurement unit that measures the distance between the first gripping unit and the second gripping unit, causing the computer to function as a control unit that drives the drive unit based on the distance measured by the measurement unit; A control program for the stretcher device.

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