Workpiece bending angle measuring method and bending machine

Abstract

This workpiece bending angle measuring method comprises: a bending process for bending a workpiece (W) by operating a bend beam (30) to which standard bending molds (40, 41) are attached in a state where the workpiece (W) is fixed to a workpiece reference surface (Pw) by pressing the workpiece (W) with a top die (25) and a bottom die (15); and a measuring process for measuring the bending angle of the workpiece (W). An angle measuring unit (60) that irradiates the workpiece (W) with a laser beam for measuring the bending angle is mounted on the bend beam (30). The measuring process includes a switching step for switching the direction of the laser beam applied to the workpiece W in accordance with the bending direction of the workpiece (W) bent in the bending process.

Description

Workpiece bending angle measurement method and bending machine

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

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

[0003] The rotary bending machine described in Patent Document 1 is equipped with an angle measurement system that measures the bending angle without contact 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.

[0004] International Publication No. 2017 / 181208

[0005] However, according to the technique disclosed in Patent Document 1, when bending two or more times, the laser light emitted 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.

[0006] One aspect of one or more embodiments is a method for measuring a workpiece bend angle, comprising: a bending step of bending the workpiece by operating a bend beam equipped with a bending die while the workpiece is fixed relative to a workpiece reference surface by pressing the workpiece with a top die and a bottom die; and a measuring step of measuring the bend 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, and the measuring step includes a switching step of switching the direction of the detection light irradiated on the workpiece depending on the bending direction of the workpiece bent in the bending step.

[0007] According to this workpiece bending angle measurement method, the direction of the laser light can be switched depending on the bending direction of the workpiece bent in the bending process, thereby preventing the laser light emitted from the angle measurement unit from being blocked by the bending area of ​​the workpiece bent in the preceding bending process.

[0008] According to one or more embodiments of the workpiece bending angle measurement method, the bending area of ​​the workpiece to be measured can be appropriately irradiated with laser light, thereby enabling the bending angle of the workpiece to be measured with high accuracy.

[0009] Fig. 1 is a side view schematically showing a main part of a bending machine according to this embodiment. Fig. 2 is a front view schematically showing a main part of a bend beam of the bending machine according to this embodiment. Fig. 3 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. Fig. 4 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. Fig. 5 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. Fig. 6 is a diagram showing the concept of a method for bending a workpiece W using a bending machine. Fig. 7 is a diagram showing a modified example of the bending machine.

[0010] Hereinafter, a workpiece bending angle measuring method and a bending machine according to this 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 schematically showing the main parts of the bending machine 1 according to this embodiment. Figure 2 is a front view schematically showing the main parts 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 left side of the bend beam 30 has the same configuration.

[0012] In describing the configuration of the bending machine 1, directions are defined as left-right, front-rear, and up-down. The left-right and front-rear directions correspond to two directions that are orthogonal to the horizontal direction, and the up-down direction corresponds to the vertical direction. In the drawings, the right, left, up, down, front, and rear directions are indicated by RT, LT, UP, DN, FR, and RR, respectively. 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 convenience in describing the bending machine according to this embodiment.

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

[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 in the left-right direction. A bottom die 15 serving as a fixed mold is provided on the upper part of the lower frame 10.

[0016] The upper frame 20 is formed to be long in the left-right direction. A top die 25 as a movable mold is provided at the bottom 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 frame drive mechanism moves the upper frame 20 downward, the bottom die 15 and the top die 25 press against the workpiece W. This pressing fixes the workpiece W and positions the workpiece W on the workpiece reference plane Pw. Conversely, when the frame drive mechanism moves the upper frame 20 upward, 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 drive mechanism (not shown). The movement of the bend beam 30 in the up-down and front-rear directions causes the front end of the bend beam 30 to move in an arc.

[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 to perform positive bending, that is, bending 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 of the vertical frame 31 in the up-down direction 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] As shown in Fig. 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 fitted with a dedicated die for performing bending processes 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 bending of cut-and-raised portions, etc. The left-right size of the bending unit 50 is set 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-side bending unit 50 and a left-side bending unit 50. Each bending unit 50 is positioned in accordance with the processing position of the workpiece W by moving left and right in the left-right direction via a drive mechanism (not shown).

[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 opposite each other. Similar to the bend beam 30, the bending unit 50 has a C-shaped cross section with an opening at the front. Dedicated dies can be attached to the front ends of the lower plate 51 and upper plate 52 of the bending unit 50, as needed.

[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 of the bending unit 50 moves in an arc, thereby bending the workpiece W.

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

[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 captures an image of the workpiece W irradiated with the laser light. That is, the imaging device 62 captures an image 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 measurement 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. Details of this operation mode will be described later.

[0034] When measuring the bending angle using the angle measurement 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 measurement 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 various functions of the control device 100 are realized by having the hardware processor execute programs stored in the memory.

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

[0037] Furthermore, the control device 100 calculates the bending angle of the workpiece W by performing image processing based on the bending angle measurement results output from the angle measurement unit 60, i.e., the images captured by the imaging device 62. Note that the calculation of the bending angle does not necessarily have to be performed by the control device 100. The angle measurement unit 60 may be equipped with a processing circuit 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 the workpiece W is fixed to the workpiece reference plane Pw by pressing the workpiece W with the top die 25 and the bottom die 15, and then a bend beam 30 equipped with standard bending dies 40, 41 is operated to bend the workpiece W, and a measurement process in which the bend angle of the workpiece W is measured. The bend beam 30 is equipped with an angle measurement unit 60 that irradiates the workpiece W with a laser beam for measuring the bend angle. The measurement process includes a switching process in which the direction of the laser beam irradiated onto the workpiece W is switched depending on the bending direction of the workpiece W bent in the bending process.

[0040] Below, we will explain in detail the bending method for the workpiece W, 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 at a position inside the workpiece that is further inside 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 Figure 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. After bending the workpiece W is complete, the control device 100 controls the attitude of the bend beam 30 so that the opening of the bend beam 30 faces forward.

[0043] 3 and step c1 in 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 measurement unit 60 mounted on the bending unit 50, i.e., the position of the laser light irradiated onto the workpiece W from the angle measurement unit 60, 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 relative to the reference posture of the bend beam 30 in which the center of the laser beam coincides with the workpiece reference plane Pw. By moving the bend beam 30 to the positive bend measurement posture, the direction of the laser beam irradiated onto 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 bending 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 bending measurement position described below).

[0046] The angle measurement unit 60 irradiates the workpiece W with laser light and takes an image of the workpiece W irradiated with the laser light. The control device 100 identifies the bending angle of the workpiece W by processing the captured image.

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

[0048] As shown in step d1 of Fig. 4, the control device 100 performs a new forward bending process. Specifically, the control device 100 operates the bend beam 30 to perform a forward bending of the workpiece W using the standard bending die for forward bending 40. 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 Figure 5, the control device 100 performs a bending process 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. After bending of the workpiece W is complete, 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 bend measurement position (step c2). The reverse bend measurement position is a position in which the bend beam 30 is rotated so that the laser light is directed downward by a predetermined angle relative to the reference position of the bend beam 30. By the bend beam 30 being in the reverse bend measurement position, the direction of the laser light irradiated onto the workpiece W is switched according to the bending direction (downward) of the workpiece (switching step).

[0053] The angle measurement unit 60 irradiates the workpiece W with laser light and takes an image of the workpiece W irradiated with the laser light. The control device 100 identifies the bending angle of the workpiece W by processing the captured image.

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

[0055] As shown in step d2 of Fig. 6, the control device 100 performs a reverse bending process 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] The bending process for the workpiece W is completed through the above series of steps.

[0057] As described above, the workpiece bending angle measuring method according to this embodiment includes a switching step of switching the direction of the laser beam depending on the bending direction of the workpiece W bent in the bending step. Specifically, when the bending step is a forward bending step in which the workpiece W is bent upward using the standard bending die for forward bending 40 provided below the front end of the bend beam 30, the switching step switches the laser beam upward from a state in which the center of the laser beam is parallel to the workpiece reference plane Pw. On the other hand, when the bending step is a reverse bending step in which the workpiece W is bent downward using the standard bending die for reverse bending 41 provided above the front end of the bend beam 30, the switching step switches the direction of the laser beam downward from a state in which the center of the laser beam is parallel to the workpiece reference plane Pw.

[0058] According to this method, the direction of the laser light can be switched depending on 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 onto 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 captures an image of the reflected light of the laser light irradiated onto the workpiece W.

[0060] With this angle measurement unit 60, it is only necessary to select either the forward bending measurement position or the reverse bending measurement position depending on the bending direction of the bending region to be measured for the bending angle, and there is no need to change to multiple positions when measuring the angle of this bending region. This allows for efficient angle measurement.

[0061] In this embodiment, the switching step is a step of rotating 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 therein can also be rotated. This makes it possible to appropriately switch the direction of the laser light depending on 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 is configured to be 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 that can be fitted with a dedicated die for performing bending processes that cannot be performed with the standard bending dies 40, 41 attached to the bend beam 30.

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

[0065] In this embodiment, the direction of the laser beam is switched by rotating the bend beam 30. 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 involve rotating only the angle measurement unit 60 while the bend beam 30 remains stationary. Alternatively, the bend beam 30 may be rotated, and then the angle measurement unit 60 may be further 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 onto the workpiece W. In this case, the switching step may switch the direction of the laser light irradiated onto 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 left and right by moving the bending unit 50 left and right. 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 left and right may be provided.

[0068] In the above-described embodiment, an example has been shown in which the bending angle is measured by the angle measurement unit 60 mounted on one of 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 angles 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 left and right and measuring the bending angles at multiple positions.

[0069] Furthermore, this embodiment is not limited to the workpiece bend angle measurement method, but also extends to a bending machine 1 that executes this method. That is, the bending machine 1 includes an upper frame 20 that is provided with a top die 25 and that is movable in the vertical direction, a lower frame 10 that is provided with a bottom die 15 that faces the top die 25, and a bend beam 30 that bends the workpiece W while 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 measurement unit 60 that irradiates the workpiece W with a laser beam for measuring the bend angle of the workpiece W. The angle measurement unit 60 has an operation mode for switching the direction of the laser beam irradiated onto the workpiece W depending on the bending direction of the workpiece W bent by the bending process.

[0070] Although the present embodiment has been described above, the description and drawings forming a part of this embodiment should not be understood as limiting this embodiment. From this embodiment, various alternative embodiments, examples and operation techniques will become apparent to those skilled in the art.

[0071] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-165230, filed with the Japan Patent Office on September 27, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. A method for measuring a work bending angle, comprising: a bending process for bending the work by operating a bend beam equipped with a bending die while fixing the work against a work reference surface by pressing the work with a top die and a bottom die; and a measuring process for measuring the bending angle of the work, wherein the bend beam is equipped with an angle measuring unit that irradiates the work with detection light for measuring the bending angle, and the measuring process includes a switching process for switching the direction of the detection light irradiated to the work depending on the bending direction of the work bent in the bending process.

2. A workpiece bending angle measuring method as described in claim 1, wherein, when the bending process is forward bending in which the workpiece is bent upward by a bending die for forward bending provided at the lower part of the front end side of the bend beam, the switching process switches the detection light to be upward rather than a state in which the center of the detection light is parallel to the workpiece reference surface; and, when the bending process is reverse bending in which the workpiece is bent downward by a bending die for reverse bending provided at the upper part of the front end side of the bend beam, the switching process switches the detection light to be downward rather than a state in which the center of the detection light is parallel to the workpiece reference surface.

3. A work bending angle measuring method as described in claim 1, wherein the angle measuring unit includes: an irradiation device that irradiates the work with the detection light; and an imaging device that images the work irradiated with the detection light.

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

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

6. A method for measuring a workpiece bend angle as claimed in any one of claims 1 to 3, wherein the bend beam has a moving unit arranged inside the bend beam and configured to be freely movable along the longitudinal direction of the bend beam, and the angle measuring unit is mounted on the moving unit.

7. The method for measuring a workpiece bending angle according to claim 6, wherein the moving unit is a unit capable of mounting a dedicated die for performing bending processing that cannot be performed by the bending die mounted on the bend beam.

8. A method for measuring a work bending angle as described in any one of claims 1 to 3, wherein the angle measurement unit includes an optical system that switches the direction of the detection light irradiated to the workpiece, and the switching process switches the direction of the detection light irradiated to the workpiece by the optical system.

9. A bending machine comprising: an upper frame having a top die and movable in a vertical direction; a lower frame having a bottom die opposite the top die; and a bend beam that bends a workpiece while the workpiece is fixed to a workpiece reference surface by the top die and the bottom die, wherein the bend beam has an angle measurement unit that irradiates the workpiece with detection light for measuring the bending angle of the workpiece, and the angle measurement unit has an operating mode for switching the direction of the detection light irradiated to the workpiece depending on the bending direction of the workpiece bent by the bending process.

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