Measurement method of work-piece bending angle, and bending process machine

Abstract

To accurately measure a work-piece bending angle.SOLUTION: A measurement method of a work-piece bending angle comprises: a bending process which performs bending of the work-piece W through moving a bend beam 30 with standard bending molds 40, 41 in a condition that a top die 25 and a bottom die 15 press the work-piece W to fix the work-piece W relative to a work-piece reference face Pw; and a measurement process which measures a bending angle of the work-piece W. The bend beam 30 includes an angle measurement unit 60 which irradiates the work-piece W with laser beam to measure the bending angle. The measurement process includes a switching process which switches direction of the laser beam with which the work-piece W is irradiated according to bending direction of the work-piece W bended at the bending process.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a workpiece bending angle measuring method and a bending machine. [Background technology]

[0002] There is known a bending machine that includes a top die, a bottom die that faces the top die below, and a bend beam that is provided behind the top die and the bottom die. In this bending machine, the bend beam is swung by moving in the up-down and back-and-forth directions while a workpiece is fixed by the top die and the bottom die. A bending die attached to the front upper part or the front lower part of the bend beam bends the end of the workpiece that protrudes rearward from the top die and the bottom die (iron bending).

[0003] The turning bending machine described in Patent Document 1 is provided with an angle measurement system that measures the bending angle in a non-contact manner inside a bend beam having a C-shaped cross section. The angle measurement system includes a first angle measurement unit that is arranged below a reference plane on which a workpiece is placed, and a second angle measurement unit that is arranged above the reference plane on which the workpiece is placed. The first angle measurement unit has a measurement range above the reference plane, and the second angle measurement unit has a measurement range below the reference plane. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 181208 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the method disclosed in Patent Document 1, when performing two or more bending operations, the laser light irradiated from the angle measurement unit may be blocked by the bending area of ​​the workpiece bent in the preceding bending process, making it impossible to measure the angle of the bending area to be measured. [Means for solving the problem]

[0006] One embodiment of the present invention provides a method for measuring a workpiece bend angle, comprising a bending process in which a bend beam equipped with a bending die is operated to bend the workpiece while the workpiece is fixed against a workpiece reference surface by pressing the workpiece with a top die and a bottom die, and a measurement process in which the bend angle of the workpiece is measured, wherein the bend beam is equipped with an angle measurement unit that irradiates the workpiece with detection light for measuring the bend angle, and the measurement process includes a switching process in which the direction of the detection light irradiated to the workpiece is switched depending on the bending direction of the workpiece bent in the bending process.

[0007] According to this workpiece bending angle measuring method, the direction of the laser light can be switched according to the bending direction of the workpiece bent in the bending process, which makes it possible to prevent the laser light irradiated from the angle measuring unit from being blocked by the bending region of the workpiece bent in the preceding bending process. Effect of the Invention

[0008] According to one aspect of the present invention, since the bending region of the workpiece to be measured can be appropriately irradiated with laser light, the bending angle of the workpiece can be measured with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing a schematic view of a main part of a bending machine according to the present embodiment. [Diagram 2] FIG. 2 is a front view showing a schematic view of a main part of a bend beam of the bending machine according to the present embodiment. [Diagram 3]FIG. 3 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. [Figure 4] FIG. 4 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. [Diagram 5] FIG. 5 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. [Figure 6] FIG. 6 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. [Figure 7] FIG. 7 is a diagram showing a modified example of the bending machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a workpiece bending angle measuring method and a bending machine according to the present embodiment will be described with reference to the drawings.

[0011] First, a bending machine 1 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a side view showing a schematic view of a main part of the bending machine 1 according to this embodiment. Figure 2 is a front view showing a schematic view of a main part of a bend beam 30 of the bending machine 1 according to this embodiment. For convenience, only the right side of the bend beam 30 is shown in Figure 2, but the configuration of the left side of the bend beam 30 is the same.

[0012] In describing the configuration of the bending machine 1, the left-right direction, the front-rear direction, and the up-down direction are used as definitions of directions. The left-right direction and the front-rear direction correspond to two directions that are perpendicular to the horizontal direction, and the up-down direction corresponds to the vertical direction. In Fig. 1, the vertical direction of the paper surface corresponds to the left-right direction, and in Fig. 2, the vertical direction of the paper surface corresponds to the front-rear direction. However, these directions are merely defined for the sake of convenience in describing the processing machine according to this embodiment.

[0013] The bending machine 1 is a processing machine that bends the plate-shaped workpiece W into a desired shape by performing bending (ironing) on ​​the edge portion of the workpiece W, and is called a panel bender. In front of the bending machine 1, a manipulator (not shown) that supplies and positions the workpiece W is disposed.

[0014] As shown in FIG. 1, the bending machine 1 includes a lower frame 10, an upper frame 20, a bottom die 15, a top die 25, a bend beam 30, and a control device 100.

[0015] The lower frame 10 is formed to be long horizontally along the left-right direction. A bottom die 15 serving as a fixed mold is provided on the upper portion of the lower frame 10.

[0016] The upper frame 20 is formed to be long horizontally along the left-right direction. A top die 25 as a movable mold is provided at the lower part of the upper frame 20 and faces the bottom die 15.

[0017] The upper frame 20 is configured to be movable in the vertical direction, and is driven by a frame drive mechanism (not shown). When the upper frame 20 is moved downward by the frame drive mechanism, the bottom die 15 and the top die 25 press the workpiece W. This pressing fixes the workpiece W and positions the workpiece W on the workpiece reference plane Pw. Conversely, when the upper frame 20 is moved upward by the frame drive mechanism, the top die 25 moves away from the workpiece W, thereby releasing the fixation of the workpiece W.

[0018] The bend beam 30 is disposed behind the bottom die 15 and the top die 25. The bend beam 30 extends in the left-right direction. The bend beam 30 is configured to be movable in the front-rear and up-down directions, and is driven by a bend beam driving mechanism (not shown). The front end side of the bend beam 30 moves in an arc due to the movement in the up-down and front-rear directions.

[0019] As shown in FIGS. 1 and 2, the bend beam 30 is composed of a plurality of vertical frames 31, a lower beam 32, and an upper beam 33.

[0020] The vertical frames 31 are arranged at regular intervals in the left-right direction. Each vertical frame 31 has a C-shaped cross section with an opening, and is arranged so that the opening faces forward.

[0021] The lower beam 32 is provided on the lower surfaces of the multiple vertical frames 31 and extends in the left-right direction. A standard bending die 40 for positive bending is attached to the front end of the lower beam 32 for performing positive bending to bend the workpiece W upward.

[0022] The upper beam 33 is provided on the upper surfaces of the multiple vertical frames 31 and extends in the left-right direction. A standard reverse bending die 41 for reverse bending the workpiece W downward is attached to the front end of the upper beam 33.

[0023] A base member 35 is provided inside the bend beam 30. The base member 35 is disposed at approximately the center in the up-down direction of the vertical frame 31 and extends in the left-right direction. The left-right dimension of the base member 35 is larger than the left-right dimension of the bend beam 30.

[0024] 2, the right end of the base member 35 has a right extension 35a that protrudes a certain amount to the right beyond the right end of the bend beam 30. Although not shown in FIG. 2, the left end of the base member 35 has a left extension 35a that protrudes a certain amount to the left beyond the left end of the bend beam 30.

[0025] The bend beam 30 is provided with a pair of bending units 50. Each bending unit 50 can be equipped with a dedicated die for performing bending processing that cannot be performed with the standard bending dies 40, 41 attached to the bend beam 30. The dedicated die attached to the bending unit 50 can perform bending of a thin workpiece W, acute angle bending, cutting and raising bending in which a cut-and-raised portion is bent, and the like. The left-right size of the bending unit 50 is set to be smaller than the left-right size of the bend beam 30.

[0026] The pair of bending units 50 are each attached to the base member 35, and are divided into a right bending unit 50 and a left bending unit 50. Each bending unit 50 is moved left and right by a drive mechanism (not shown) to be positioned in a position appropriate for the processing of the workpiece W.

[0027] Furthermore, when bending is performed using the standard bending dies 40, 41 attached to the bend beam 30, the right bending unit 50 is retracted to the right extension 35a of the base member 35. Similarly, the left bending unit 50 is retracted to the left extension 35a of the base member 35. This makes it possible to prevent the pair of bending units 50 from interfering with the workpiece W or parts of the mechanism such as the bottom die 15 and the top die 25 during bending using the standard bending dies 40, 41.

[0028] The bending unit 50 includes a lower plate 51 and an upper plate 52 arranged facing each other vertically. The bending unit 50 has a C-shaped cross section with an opening at the front, similar to the bend beam 30. A dedicated die can be attached to the front end of the lower plate 51 and the front end of the upper plate 52 of the bending unit 50, as necessary.

[0029] In this embodiment, the bending unit 50 is attached to the base member 35 of the bend beam 30. Therefore, when bending is performed using the bending unit 50 equipped with a dedicated die, the bend beam 30 moves in the up-down and front-back directions. In response to the up-down and front-back movements of the bend beam 30, the front end side of the bending unit 50 moves to draw an arc, thereby allowing the workpiece W to be bent.

[0030] An angle measuring unit 60 is provided inside the bending unit 50. The angle measuring unit 60 measures the bending angle of the workpiece W. The angle measuring unit 60 can move in the left-right direction as the bending unit 50 moves. The angle measuring unit 60 can move in the up-down direction and the front-back direction as the bend beam 30 moves in the up-down direction and the front-back direction.

[0031] The angle measurement unit 60 includes an illumination device 61 and an imaging device 62. In Fig. 2, the illumination device 61 is disposed on the left side, and the imaging device 62 is disposed on the right side. However, the positions of the illumination device 61 and the imaging device 62 may be reversed.

[0032] The irradiation device 61 irradiates the workpiece W with laser light (an example of detection light). The irradiation device 61 irradiates the workpiece W with planar fan-shaped laser light emitted from a point light source, or planar rectangular laser light emitted from a line light source. The imaging device 62 images the workpiece W irradiated with the laser light. That is, the imaging device 62 images the reflected light of the laser light reflected by the workpiece W. The image captured by the imaging device 62, which is the measurement result of the bending angle, is output to the control device 100.

[0033] In this embodiment, the angle measuring unit 60 has an operation mode for switching the direction of the laser light irradiated onto the workpiece W in accordance with the bending direction of the workpiece W bent by bending processing. The details of this operation mode will be described later.

[0034] When measuring the bending angle using the angle measuring unit 60, it is preferable to perform the measurement with the dedicated die detached from the bending unit 50. This is to prevent the laser light emitted from the angle measuring unit 60 or the light reflected by the workpiece W from being blocked by the dedicated die.

[0035] The control device 100 is configured by a computer having a hardware processor such as a CPU (Central Processing Unit), a memory, and various interfaces. The memory and various interfaces are connected to the hardware processor via a bus. The hardware processor executes a program stored in the memory, thereby realizing various functions of the control device 100.

[0036] The control device 100 controls the operation of the bending machine 1. Specifically, the control device 100 controls the up-down movement of the upper frame 20, the front-rear and up-down movement of the bend beam 30, the left-right movement of the pair of bending units 50, etc.

[0037] Furthermore, the control device 100 performs image processing based on the measurement result of the bending angle output from the angle measurement unit 60, i.e., the image captured by the imaging device 62, to calculate the bending angle of the workpiece W. Note that the calculation of the bending angle is not limited to being performed by the control device 100. The angle measurement unit 60 may be equipped with a processing circuit to cause the angle measurement unit 60 to calculate the bending angle of the workpiece W.

[0038] 3 to 6, a method for bending a workpiece W using the bending machine 1 will be described below. This method for bending a workpiece W includes a method for measuring a workpiece bending angle, which is one of the features of this embodiment.

[0039] The workpiece bend angle measuring method according to this embodiment includes a bending process in which a bend beam 30 equipped with standard bending dies 40, 41 is operated to bend the workpiece W in a state in which the workpiece W is fixed against the workpiece reference plane Pw by pressing the workpiece W with the top die 25 and the bottom die 15, and a measuring process in which the bend angle of the workpiece W is measured. The bend beam 30 is equipped with an angle measuring unit 60 that irradiates the workpiece W with a laser beam for measuring the bend angle. The measuring process includes a switching process in which the direction of the laser beam irradiated to the workpiece W is switched depending on the bending direction of the workpiece W bent in the bending process.

[0040] Below, a specific method for bending a workpiece W will be explained using as an example a situation in which a forward bend is performed parallel to the edge of the workpiece W, and then a reverse bend is performed parallel to the edge of the workpiece W on the inside of the first bending position.

[0041] First, the control device 100 operates the movable frame 22 to fix the workpiece W, which has been positioned for the first bending, that is, the forward bending, by the bottom die 15 and the top die 25.

[0042] As shown in step a1 of Fig. 3, the control device 100 performs a bending process for a positive bend. Specifically, the control device 100 operates the bend beam 30 to perform a positive bend on the workpiece W using the standard bending die 40 for positive bending. At this time, the control device 100 controls the operation of the bend beam 30 so that the workpiece W is bent to an extent that does not completely reach the target bend angle. When bending of the workpiece W is completed, the control device 100 controls the attitude of the bend beam 30 so that the opening of the bend beam 30 faces forward.

[0043] Next, as shown in step b1 of Fig. 3 and step c1 of Fig. 4, the control device 100 performs a measurement step of measuring the bending angle of the workpiece W. Specifically, the control device 100 moves one of the left and right bending units 50 in the left-right direction and positions the bending unit 50 to a predetermined position (step b1). By this positioning, the position of the angle measuring unit 60 mounted on the bending unit 50, i.e., the position of the laser light irradiated from the angle measuring unit 60 to the workpiece W, is aligned with the position on the workpiece W whose angle is to be measured.

[0044] At the same time, the control device 100 moves the bend beam 30 to a positive bend measurement posture (step c1). The positive bend measurement posture is a posture in which the bend beam 30 is rotated so that the laser beam is directed upward by a predetermined angle with respect to the reference posture of the bend beam 30 in which the center of the laser beam coincides with the workpiece reference surface Pw. By the bend beam 30 being in the positive bend measurement posture, the direction of the laser beam irradiated to the workpiece W is switched according to the bending direction (upward) of the workpiece (switching step).

[0045] In addition, when moving the bend beam 30 to the forward bend measurement position, the control device 100 also controls the position of the bend beam 30 so that the angle measurement unit 60 is at a predetermined reference distance from the bottom die 15 and the top die 25 (the same applies to the reverse bend measurement position described below).

[0046] The angle measuring unit 60 irradiates the workpiece W with a laser beam and captures an image of the workpiece W irradiated with the laser beam. The control device 100 identifies the bending angle of the workpiece W by performing image processing on the captured image.

[0047] Then, the control device 100 moves one of the bending units 50 in the left-right direction, and retreats the bending unit 50 to the extension portion 35a of the base member 35.

[0048] As shown in step d1 of Fig. 4, the control device 100 performs a bending process for a positive bend again. Specifically, the control device 100 operates the bend beam 30 to perform a positive bend on the workpiece W using the standard bending die 40 for positive bending. At this time, the control device 100 controls the operation of the bend beam 30 based on the difference between the measured bending angle of the workpiece W and the target bending angle, so that the bending angle of the workpiece W matches the target bending angle.

[0049] Next, the control device 100 raises the upper frame 20 and positions the workpiece W for the second bending process, which is reverse bending. The control device 100 operates the movable frame 22 to fix the workpiece W between the bottom die 15 and the top die 25.

[0050] As shown in step a2 of Fig. 5, the control device 100 performs a bending step for reverse bending. Specifically, the control device 100 operates the bend beam 30 to perform reverse bending on the workpiece W using the standard bending die for reverse bending 41. At this time, the control device 100 controls the operation of the bend beam 30 so that the workpiece W is bent to an extent that does not completely reach the target bending angle. When bending of the workpiece W is completed, the control device 100 controls the attitude of the bend beam 30 so that the opening of the bend beam 30 faces forward.

[0051] Next, as shown in step b2 of Fig. 5 and step c2 of Fig. 6, the control device 100 performs a measurement step of measuring the bending angle of the workpiece W. Specifically, the control device 100 moves one of the left and right bending units 50 in the left-right direction, and positions the bending unit 50 at a predetermined position (step b2).

[0052] At the same time, the control device 100 moves the bend beam 30 to a reverse bending measurement posture (step c2). The reverse bending measurement posture is a posture in which the bend beam 30 is rotated so that the laser light is directed downward by a predetermined angle with respect to the reference posture of the bend beam 30. By the bend beam 30 being in the reverse bending measurement posture, the direction of the laser light irradiated to the workpiece W is switched according to the bending direction (downward) of the workpiece (switching step).

[0053] The angle measuring unit 60 irradiates the workpiece W with a laser beam and captures an image of the workpiece W irradiated with the laser beam. The control device 100 identifies the bending angle of the workpiece W by performing image processing on the captured image.

[0054] Then, the control device 100 moves one of the bending units 50 in the left-right direction, and retreats the bending unit 50 to the extension portion 35a of the base member 35.

[0055] As shown in step d2 of Fig. 6, the control device 100 performs the bending process for reverse bending again. The control device 100 operates the bend beam 30 to perform reverse bending on the workpiece W using the standard bending die for reverse bending 41. At this time, the control device 100 controls the operation of the bend beam 30 based on the difference between the measured bending angle of the workpiece W and the target bending angle so that the bending angle of the workpiece W matches the target bending angle.

[0056] Through the above series of steps, the bending of the workpiece W is completed.

[0057] In this way, the workpiece bending angle measuring method according to the present embodiment includes a switching step of switching the direction of the laser light depending on the bending direction of the workpiece W bent in the bending step. Specifically, in the case of forward bending in which the workpiece W is bent upward by the standard bending die for forward bending 40 provided at the lower part of the front end side of the bend beam 30, the switching step switches the laser light upward from the state in which the center of the laser light is parallel to the workpiece reference plane Pw. On the other hand, in the case of reverse bending in which the workpiece W is bent downward by the standard bending die for reverse bending 41 provided at the upper part of the front end side of the bend beam 30, the switching step switches the direction of the laser light downward from the state in which the center of the laser light is parallel to the workpiece reference plane Pw.

[0058] According to this method, the direction of the laser light can be switched according to the bending direction of the workpiece W bent in the bending process. This makes it possible to prevent the laser light irradiated from the angle measurement unit 60 from being blocked by the bending region of the workpiece W bent in the preceding bending process. Since the laser light can be appropriately irradiated to the bending region of the workpiece W to be measured, the bending angle of the workpiece W can be measured with high accuracy.

[0059] In this embodiment, the angle measurement unit 60 includes an irradiation device 61 that irradiates the workpiece W with laser light, and an imaging device 62 that images the reflected light of the laser light irradiated onto the workpiece W.

[0060] According to this angle measuring unit 60, it is only necessary to select the normal bending measurement posture or the reverse bending measurement posture according to the bending direction of the bending region to be measured for the bending angle, and it is not necessary to change to a plurality of postures when measuring the angle of this bending region. This allows efficient angle measurement.

[0061] In this embodiment, the switching step is a step of pivoting the bend beam 30 to which the angle measurement unit 60 is fixed.

[0062] According to this process, by rotating the bend beam 30 that operates to bend the workpiece W, the angle measurement unit 60 fixed inside the bend beam 30 can also be rotated. This makes it possible to appropriately switch the direction of the laser light according to the bending direction of the workpiece W.

[0063] In this embodiment, the bend beam 30 has a moving unit that is disposed inside the bend beam 30 and configured to be freely movable along the longitudinal direction of the bend beam 30. The angle measurement unit 60 is mounted on the moving unit. This moving unit is a bending unit 50 to which a dedicated die can be attached for performing bending processing that cannot be performed with the standard bending dies 40, 41 attached to the bend beam 30.

[0064] According to this configuration, the angle measuring unit 60 can be moved in conjunction with the left-right movement of the bending unit 50. This allows the angle measuring unit 60 to be appropriately positioned with respect to the measurement position of the workpiece W.

[0065] In this embodiment, the bend beam 30 is rotated as a method for switching the direction of the laser light. However, as shown in FIG. 7, a rotation mechanism 63 for rotating the angle measurement unit 60 may be mounted on the bending unit 50. In this configuration, the switching process may rotate only the angle measurement unit 60 while the bend beam 30 is stationary. In addition, the bend beam 30 may be rotated, and then the angle measurement unit 60 may be rotated. This ensures the rotation angle required for angle measurement even when the rotation angle of the bend beam 30 is insufficient.

[0066] Furthermore, the angle measurement unit 60 may include an optical system that switches the direction of the laser light irradiated to the workpiece W. In this case, the switching step may switch the direction of the laser light irradiated to the workpiece W by the optical system.

[0067] In the above-described embodiment, the angle measurement unit 60 is mounted on the bending unit 50, and the angle measurement unit 60 is moved in the left-right direction by the left-right movement of the bending unit 50. However, in the case of a model that does not include the bending unit 50, a dedicated mechanism for moving the angle measurement unit 60 in the left-right direction may be provided.

[0068] In the above embodiment, an example was shown in which the bending angle was measured by the angle measurement unit 60 mounted on one of the bending units 50 among the angle measurement units 60 mounted on the left and right bending units 50. However, the angle measurement units 60 mounted on the left and right bending units 50 may each measure the bending angle. Since the bending angle can be measured at multiple positions in the bending area, the accuracy of the bending process can be evaluated. However, the angle measurement unit 60 may be mounted on only one of the left and right bending units 50. Even in this case, the accuracy of the bending process can be evaluated by moving one of the bending units 50 in the left and right direction to measure the bending angle at multiple positions.

[0069] In addition, this embodiment is not limited to the workpiece bending angle measuring method, but also extends to a bending machine 1 that executes this method. That is, the bending machine 1 includes an upper frame 20 on which a top die 25 is provided and which is movable in the vertical direction, a lower frame 10 on which a bottom die 15 facing the top die 25 is provided, and a bend beam 30 that bends the workpiece W in a state in which the workpiece W is fixed to a workpiece reference plane Pw by the top die 25 and the bottom die 15. The bend beam 30 includes an angle measuring unit 60 that irradiates the workpiece W with a laser beam for measuring the bending angle of the workpiece W. The angle measuring unit 60 includes an operation mode for switching the direction of the laser beam irradiated to the workpiece W according to the bending direction of the workpiece W bent by bending.

[0070] As described above, the present embodiment has been described, but the description and drawings forming a part of this embodiment should not be understood as limiting this embodiment. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this embodiment. [Explanation of symbols]

[0071] 1 Bending machine 10 Lower Frame 15 Bottom Die 20 Upper Frame 25 Top Die 30 Bend Beam 40 Standard bending die for positive bending 41 Standard bending die for reverse bending 50 bending unit 60 Angle Measuring Unit 61 Irradiation device 62 Imaging Device 100 Control device Pw Work reference surface Double work

Claims

1. a bending process in which a bend beam having a bending die attached thereto is operated to bend the workpiece while the workpiece is fixed relative to a workpiece reference surface by pressing the workpiece with a top die and a bottom die; A measuring step of measuring a bending angle of the workpiece, The bend beam is equipped with an angle measurement unit that irradiates the workpiece with detection light for measuring the bend angle, The measuring step includes: A switching step of switching the direction of the detection light irradiated to the workpiece in accordance with the bending direction of the workpiece bent in the bending step. How to measure workpiece bending angle.

2. In the case where the bending process is a positive bending process in which the workpiece is bent upward by a positive bending die provided at the lower part of the front end side of the bend beam, The switching step switches the detection light to be directed upward from a state in which the center of the detection light is parallel to the workpiece reference surface, In the case where the bending step is a reverse bending step in which the workpiece is bent downward by a bending die for reverse bending provided at an upper portion of the front end side of the bend beam, The switching step switches the detection light to a lower direction than a state in which the center of the detection light is parallel to the workpiece reference surface.

2. The method for measuring a workpiece bending angle according to claim 1.

3. The angle measurement unit is an irradiation device that irradiates the workpiece with the detection light; and an imaging device that images the workpiece irradiated with the detection light.

2. The method for measuring a workpiece bending angle according to claim 1.

4. The switching step is a step of rotating the bend beam. The method for measuring a workpiece bending angle according to any one of claims 1 to 3.

5. The switching step is a step of rotating only the angle measurement unit while keeping the bend beam stationary. The method for measuring a workpiece bending angle according to any one of claims 1 to 3.

6. The bend beam is A moving unit is disposed inside the bend beam and configured to be movable along a longitudinal direction of the bend beam, The angle measurement unit is mounted on the moving unit. The method for measuring a workpiece bending angle according to any one of claims 1 to 3.

7. The moving unit is a unit to which a dedicated die can be attached for performing bending processing that cannot be performed by the bending die attached to the bend beam.

7. The method for measuring a workpiece bending angle according to claim 6.

8. The angle measurement unit is An optical system for switching the direction of the detection light irradiated to the workpiece, The switching step includes: The optical system switches the direction of the detection light irradiated onto the workpiece. The method for measuring a workpiece bending angle according to any one of claims 1 to 3.

9. an upper frame provided with a top die and movable in a vertical direction; a lower frame provided with a bottom die facing the top die; A bend beam that bends the workpiece while the workpiece is fixed to a workpiece reference surface by the top die and the bottom die. The bend beam includes an angle measuring unit that irradiates the workpiece with a detection light for measuring a bending angle of the workpiece, The angle measuring unit has an operation mode for switching the direction of the detection light irradiated onto the workpiece in accordance with the bending direction of the workpiece bent by the bending process. Bending machine.

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