Bending angle measuring device and bending angle measuring method

Abstract

To provide a bending angle measuring device capable of accurately measuring the bending angle of a workpiece even if a part of the surface of the workpiece to be irradiated with laser light is curved. [Solution] A laser diode 34 irradiates a linear laser beam onto a first flange on the front side of the punch and die and a second flange on the rear side of the workpiece bent to a target bend angle. A camera 35 captures the reflected light of the laser beam irradiated onto the first and second flanges. An image angle calculation unit 33 extracts a range of high-brightness points, excluding high-brightness points irradiated onto the curved area of ​​the first or second flange, as a straight line portion from among multiple high-brightness points sampled from a line image of the reflected light contained in the image captured by the camera 35, and calculates the image angle of a straight line obtained by linearly approximating at least the sampled high-brightness points included in the straight line portion. A bend angle conversion unit 22 converts the image angle into the bend angle of the workpiece.

Description

[Technical Field]

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

[0002] A press brake has an upper table on which a punch is attached and a lower table on which a die is attached, and the upper table is lowered onto the lower table to sandwich and bend a workpiece placed on the die between the punch and the die. The press brake also has a bend angle measuring device that measures the bend angle of the workpiece. Bend angle measuring devices are available in contact and non-contact types, and Patent Document 1 describes a non-contact type bend angle measuring device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-10666 Summary of the Invention [Problem to be solved by the invention]

[0004] Typically, a non-contact bend angle measuring device irradiates a workpiece with a linear laser beam, a camera captures the reflected light of the laser beam irradiated onto the workpiece, and measures the bend angle of the workpiece based on the angle of the linear image of the captured reflected light.The non-contact bend angle measuring device can accurately measure the bend angle of a workpiece as long as the surface of the bent workpiece that is irradiated with the laser beam is flat.

[0005] However, the edges of a workpiece being bent by a press brake may have sagging due to the shearing process. Sagging is a rounding or depression formed at the edge of the surface of a workpiece that has been sheared. If the workpiece is a long, thin plate, such as one with a thickness of 1 mm, the edge of the workpiece may sag when the workpiece is bent by the press brake. Furthermore, the edge of the workpiece may have an intentionally rounded shape known as an R-shape. In such cases, the part of the workpiece surface irradiated with the laser beam may be curved. If the part of the workpiece surface irradiated with the laser beam is curved, an error may occur in the measurement angle, making it impossible to accurately measure the bending angle of the workpiece.

[0006] There is a need for a bend angle measuring device and a bend angle measuring method that can accurately measure the bend angle of a workpiece even if part of the surface of the workpiece that is irradiated with laser light is curved. [Means for solving the problem]

[0007] A first aspect of one or more embodiments includes a laser light irradiation unit that irradiates a linear laser beam onto a first flange on a front side of the punch and the die and a second flange on a rear side of the punch and the die in a workpiece that is sandwiched between the punch and the die and bent to a target bend angle; a camera that captures reflected light of the laser beam irradiated onto the first and second flanges; an image angle calculation unit that extracts, as a straight line portion, a range of high brightness points excluding high brightness points irradiated onto an area where the first or second flange is a curved surface from a plurality of high brightness points sampled from a line image of the reflected light included in the image captured by the camera, and calculates an image angle of a straight line obtained by linearly approximating at least the sampled high brightness points included in the straight line portion; and a bend angle conversion unit that converts the image angle into a bend angle of the workpiece. The image angle calculation unit sets the lowest high-brightness point or a high-brightness point nearby among the high-brightness points based on the reflected light of the laser light irradiated onto the first and second flanges as a reference point, calculates the angle between the reference point and each high-brightness point positioned above the reference point, sets the theoretical angle of a line image due to the reflected light included in a photographed image taken by the camera of the reflected light of the laser light irradiated onto the first and second flanges of the workpiece bent to the target bending angle as a straight line portion angle, and excludes a range of high-brightness points in which the difference between the angle between the reference point and each high-brightness point and the straight line portion angle exceeds an allowable value as high-brightness points irradiated onto an area where the first or second flange is a curved surface. A bending angle measuring device is provided.

[0008] A second aspect of one or more embodiments is a method for forming a film sandwiched between a punch and a die. , so that the target bending angle is achieved.A linear laser beam is irradiated onto a first flange on the front side of the punch and the die and a second flange on the rear side of the bent workpiece, and the reflected light of the laser beam irradiated onto the first and second flanges is photographed by a camera. A linear image of the reflected light included in the photographed image by the camera is sampled to obtain a plurality of high-brightness points, and among the plurality of high-brightness points, a high brightness point located at the bottom or a high brightness point nearby the high brightness point is used as a reference point, the angle formed by the reference point and each high brightness point located above the reference point is calculated, and the theoretical angle of a line image formed by the reflected light included in a photographed image obtained by photographing the reflected light of the laser light irradiated on the first and second flanges of the work bent to the target bending angle is used as a straight line angle, and a range of high brightness points among the plurality of high brightness points where the difference between the angle formed by the reference point and each high brightness point and the straight line angle exceeds an allowable value is determined. The present invention provides a bending angle measurement method that extracts, as a straight line section, high-brightness points that are excluded as high-brightness points illuminated in an area where the first or second flange is a curved surface, generates a straight line that is a linear approximation of at least the high-brightness points included in the straight line section, calculates an image angle of the straight line, and converts the image angle into a bending angle of the workpiece. [Effects of the Invention]

[0009] According to the bend angle measuring device and bend angle measuring method of one or more embodiments, the bend angle of a workpiece can be accurately measured even if part of the surface of the workpiece onto which the laser light is irradiated is curved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the overall configuration of a press brake equipped with a bending angle measuring device according to one or more embodiments. [Figure 2] FIG. 2 is a perspective view showing angle sensors disposed in front of and behind the punch and die. [Figure 3] FIG. 3 is a block diagram illustrating a bend angle measurement device according to one or more embodiments. [Figure 4] FIG. 4 is a block diagram showing a specific example of the configuration of an image angle calculation unit included in the bending angle measurement device according to one or more embodiments. [Figure 5] FIG. 5 is a diagram showing a plurality of high-brightness points obtained by sampling a line image included in a captured image of the reflected light of laser light irradiated onto a workpiece and a die, using a camera provided in a bending angle measuring device according to one or more embodiments. [Figure 6] FIG. 6 is a diagram showing peak luminance in the luminance distribution for each line of a captured image. [Figure 7A] FIG. 7A is a diagram showing a process of determining an angle A12 formed by a high luminance point P1 and a high luminance point P2 among the plurality of high luminance points shown in FIG. 5, in a series of processes for extracting workpiece high luminance points. [Figure 7B] FIG. 7B is a diagram showing a process of determining an angle A23 formed by high luminance point P2 and high luminance point P3 among the plurality of high luminance points shown in FIG. 5, in a series of processes for extracting workpiece high luminance points. [Figure 7C] FIG. 7C is a diagram showing a process of determining an angle A34 formed by high luminance point P3 and high luminance point P4 among the plurality of high luminance points shown in FIG. 5, in a series of processes for extracting workpiece high luminance points. [Figure 7D] FIG. 7D is a diagram showing a process of determining an angle A45 formed by high luminance point P4 and high luminance point P5 among the plurality of high luminance points shown in FIG. 5, in a series of processes for extracting workpiece high luminance points. [Figure 8] FIG. 8 is a diagram showing an example of a method for extracting curved surface high brightness points obtained by reflected light of laser light irradiated onto a curved area of ​​the workpiece from among the multiple high brightness points shown in FIG. [Figure 9] FIG. 9 is a diagram showing a state in which high luminance points of a workpiece, excluding curved surface high luminance points, are extracted as straight line portions. [Figure 10] FIG. 10 is a diagram showing a state in which all high-luminance points included in the straight line portion shown in FIG. 9 are extracted. [Figure 11] FIG. 11 is a diagram showing a straight line obtained by linearly approximating all high-luminance points included in the straight line portion shown in FIG. [Figure 12] FIG. 12 is a diagram showing the image angle of the straight line shown in FIG. [Figure 13] FIG. 13 is a diagram showing another method for extracting the main reference points of the workpiece high-luminance points. [Figure 14] FIG. 14 is a flowchart illustrating the operation of one or more embodiments of a bend angle measurement device and one or more embodiments of a bend angle measurement method. DETAILED DESCRIPTION OF THE INVENTION

[0011] Bending angle measuring devices and bending angle measuring methods according to one or more embodiments will be described below with reference to the accompanying drawings.

[0012] First, an example of the overall configuration and schematic operation of a press brake 100 equipped with a bending angle measuring device according to one or more embodiments will be described using Figure 1. As shown in Figure 1, the press brake 100 is equipped with an NC (Numerical Control) device 10 that functions as a control device for controlling the press brake 100. The parts excluding the NC device 10 and the bending angle measuring device (described later) will be referred to as a press brake main body 101. The press brake 100 is equipped with an upper table 1, a lower table 3, and left and right side plates 5R and 5L. An upper die holder 2 is attached to the upper table 1, and a lower die holder 4 is attached to the lower table 3.

[0013] The upper table 1 is configured to be raised and lowered by hydraulic cylinders 6L and 6R provided on the left and right sides. The hydraulic cylinders 6L and 6R constitute a table lifting mechanism. The table lifting mechanism may include actuators other than the hydraulic cylinders 6L and 6R. The table lifting mechanism may also be configured with actuators other than the hydraulic cylinders 6L and 6R. The table lifting mechanism lowers the upper table 1 so that it approaches the lower table 3, or raises it so that it moves away from the lower table 3.

[0014] A punch Tp, which is an upper die, is attached to the upper die holder 2, and a die Td, which is a lower die, is attached to the lower die holder 4. Fig. 1 shows a modular type in which the upper die holder 2 is attached integrally along the entire length of the lower end of the upper table 1, but it may also be an intermediate plate type in which multiple intermediate plates for attaching punches Tp are attached in the longitudinal direction of the lower end of the upper table 1. The intermediate plates are also upper die holders.

[0015] Mounting a punch Tp on the upper table 1 means mounting the punch Tp on the upper die holder 2 or intermediate plate. Mounting a die Td on the lower table 3 means mounting the die Td on the lower die holder 4. Two or more punches Tp may be mounted side by side on the upper table 1, and two or more dies Td may be mounted side by side on the lower table 3.

[0016] A back gauge 40 is disposed on the rear side of the lower table 3. The back gauge 40 has stoppers 42a and 42b that move left and right along a back gauge carriage 41. Here, there are two stoppers, 42a and 42b, but the number of stoppers is not limited to two. The stoppers 42a and 42b are configured to move in the height direction and the front and rear directions as well.

[0017] The operator places the metal sheet W, which is the workpiece to be processed, on the die Td, and before sandwiching and bending the metal sheet W between the punch Tp and the die Td, the butts 42a and 42b move to positions corresponding to the die Td. The operator places the metal sheet W on the die Td so that the rear end of the metal sheet W butts against the butts 42a and 42b. In other words, the butts 42a and 42b act to determine the position of the metal sheet W in the front-to-rear direction when the metal sheet W is placed on the die Td.

[0018] An operation pendant 7 having a display unit 71 and an operation unit 72 including a plurality of operation buttons is attached via an arm 7a to the left side of the press brake 100. The operation pendant 7 is connected to an NC device 10. The NC device 10 is connected to a foot switch 8 having an open foot switch 81 that raises the upper table 1 and a close foot switch 82 that lowers the upper table 1. When the operator steps on the close foot switch 82, the upper table 1 lowers and the metal sheet W is sandwiched between the punch Tp and the die Td and bent. When the operator steps on the open foot switch 81, the upper table 1 rises and the bent metal sheet W can be removed.

[0019] The bending angle measuring device is not shown in FIG. 1. As shown in FIG. 2, angle sensors 30F and 30R, which constitute part of the bending angle measuring device, are arranged in front of and behind the die Td, respectively. The punch Tp is not shown in FIG. 2. The front-side angle sensor 30F and the rear-side angle sensor 30R have the same configuration. The angle sensors 30F and 30R are collectively referred to as angle sensor 30. In the configuration example shown in FIG. 3, the angle sensor control device 20 and the angle sensor 30 constitute the bending angle measuring device. The angle sensor control device 20 includes a straight portion angle conversion unit 21 and a bending angle conversion unit 22. The angle sensor control device 20 can be configured using a computer device.

[0020] 3, the angle sensor 30 includes a sensor board 31, a laser diode 34, and a camera 35. The sensor board 31 has an operation instruction unit 32 and an image angle calculation unit 33. As shown in FIG. 2, the housing 301 of the angle sensor 30 (30F and 30R) has a first storage section 315 that stores the sensor board 31 and the camera 35, and a second storage section 340 that stores the laser diode 34.

[0021] The laser diode 34 of the angle sensor 30F is housed in the second housing section 340 and oriented toward the metal sheet W so as to irradiate the lower surface of the front flange Wf (first flange) of the metal sheet W with a linear laser beam (hereinafter referred to as "line laser beam") indicated by the dashed dotted line. The laser diode 34 of the angle sensor 30R is housed in the second housing section 340 and oriented toward the metal sheet W so as to irradiate the lower surface of the rear flange Wr (second flange) of the metal sheet W with a line laser beam. In FIG. 2, the line laser beam irradiated onto the rear flange Wr by the laser diode 34 of the angle sensor 30R is not shown. The laser diode 34 is an example of a laser beam irradiator.

[0022] The camera 35 captures the reflected light of the line laser light irradiated onto the front flange Wf and the rear flange Wr from a position a predetermined distance away from the laser diode 34. The line laser light may also be irradiated onto the upper end of the die Td.

[0023] In Figure 3, when the NC device 10 controls the press brake main body 101 to bend the metal sheet W at a predetermined target bend angle, it sends a bend angle measurement request signal and the target bend angle to the angle sensor control device 20. The straight portion angle conversion unit 21 of the angle sensor control device 20 converts the target bend angle into a theoretical straight portion angle. When the camera 35 captures the reflected light of a line laser beam irradiated onto the front flange Wf and rear flange Wr of the metal sheet W bent to the target bend angle, the angle of the line image of the reflected light included in the captured image is determined in principle. The straight portion angle conversion unit 21 converts the target bend angle into a straight portion angle that is determined in advance corresponding to the target bend angle.

[0024] The angle of the straight line portion of the line image in the image captured by the camera 35 is, for example, the angle with respect to the horizontal direction of the frame of the captured image.

[0025] The angle sensor control device 20 transmits an instruction signal to the operation instruction unit 32 of the sensor board 31 to instruct it to irradiate a line laser beam and capture an image of the reflected light. Upon receiving the instruction signal from the angle sensor control device 20, the operation instruction unit 32 instructs the laser diode 34 to irradiate a line laser beam and instructs the camera 35 to capture an image of the reflected light. The straight line portion angle conversion unit 21 transmits the straight line portion angle to the image angle calculation unit 33. The image angle calculation unit 33 acquires the image captured by the camera 35 and calculates the image angle of the line image as described below.

[0026] As shown in Fig. 4, the image angle calculation unit 33 includes a sampling processing unit 331, a straight line portion extraction unit 332, a straight line all pixel extraction unit 333, a straight line approximation unit 334, and a straight line angle calculation unit 335. The sampling processing unit 331 samples a line image by extracting peak luminance for each of a predetermined number of lines from all of the lines constituting the input captured image. Fig. 5 shows an example of a state in which the sampling processing unit 331 has sampled a line image in frame F of the captured image. In Fig. 5 and Fig. 7A and subsequent figures described below, for simplicity of illustration, the number of lines from which peak luminance is extracted is shown to be smaller than the actual number.

[0027] In Figures 5 and 7A to 8, horizontal solid lines indicate lines from which peak brightness is extracted in the captured image. By extracting the peak brightness of the selected line by the sampling processing unit 331, pixels having high brightness points P1 to P15 can be extracted. The high brightness points P1 to P3 are high brightness points based on the reflected light of the line laser light irradiated onto the upper end of the die Td. The high brightness points P4 to P15 are high brightness points based on the reflected light of the line laser light irradiated onto the front flange Wf or the rear flange Wr. As shown in Figure 6, the high brightness points P1 to P15 indicate pixels at horizontal positions where peak brightness is obtained in the brightness distribution for each line.

[0028] 5, among the high-brightness points P4 to P15, the multiple high-brightness points on the high-brightness point P15 side are curved. This is because the multiple high-brightness points on the high-brightness point P15 side are high-brightness points based on reflected light of the line laser light irradiated onto an area where the front flange Wf or the rear flange Wr is curved due to sagging, hanging, or an R-shape of the metal sheet W. The high-brightness points based on reflected light of the line laser light irradiated onto an area where the front flange Wf or the rear flange Wr is curved are referred to as curved high-brightness points.

[0029] The straight line portion extraction unit 332 first extracts high brightness points based on the reflected light of the line laser light irradiated onto the front flange Wf or the rear flange Wr from among the high brightness points P1 to P15, excluding high brightness points based on the reflected light of the line laser light irradiated onto the die Td, as follows: The high brightness points based on the reflected light of the line laser light irradiated onto the die Td will be referred to as die high brightness points, and the high brightness points based on the reflected light of the line laser light irradiated onto the front flange Wf or the rear flange Wr will be referred to as workpiece high brightness points. The straight line portion extraction unit 332 sets a selected high brightness point from among the workpiece high brightness points as a reference point (main reference point).

[0030] As shown in FIG. 7A, the straight line segment extraction unit 332 uses, for example, the lowest high-luminance point P1 in frame F as a tentative reference point and calculates the angle A12 between the high-luminance point P1 and the next higher high-luminance point P2. The straight line segment extraction unit 332 calculates the difference between the angle A12 and the straight line segment angle. Since the difference exceeds the tolerance, the straight line segment extraction unit 332 determines that the high-luminance point P1 is a die high-luminance point. The tolerance can be set appropriately.

[0031] As shown in FIG. 7B, the straight line segment extraction unit 332 uses the high-brightness point P2 as a tentative reference point and calculates the angle A23 between the high-brightness point P2 and the high-brightness point P3 located immediately above it. The straight line segment extraction unit 332 calculates the difference between the angle A23 and the straight line segment angle. Because the difference again exceeds the allowable value, the straight line segment extraction unit 332 determines that the high-brightness point P2 is a die high-brightness point. Similarly, the difference between the angle A34 and the straight line segment angle formed by the high-brightness point P3 and the high-brightness point P4 shown in FIG. 7C also exceeds the allowable value. Therefore, the straight line segment extraction unit 332 determines that the high-brightness point P3 is a die high-brightness point.

[0032] As shown in FIG. 7D, the straight line portion extraction unit 332 sets the high-luminance point P4 as a tentative reference point and calculates the angle A45 formed between the high-luminance point P4 and the high-luminance point P5 located immediately above it. The straight line portion extraction unit 332 calculates the difference between the angle A45 and the straight line portion angle. Here, since the difference does not exceed the allowable value, the straight line portion extraction unit 332 determines that the high-luminance point P4 is a high-luminance workpiece point. The straight line portion extraction unit 332 sets the high-luminance point P4 as the final reference point. The straight line portion extraction unit 332 may also set a high-luminance point P5 located near the high-luminance point P4, for example, the high-luminance point P5 located immediately above it, as the final reference point. The straight line portion extraction unit 332 determines that the high-luminance point P4 and the high-luminance points P5 to P15 located immediately above it are high-luminance workpiece points.

[0033] As shown in FIG. 8, the straight line portion extraction unit 332 calculates angles A45 to A415 formed by the high-luminance point P4, which is the reference point, and high-luminance points P5 to P15. The straight line portion extraction unit 332 calculates the differences between the angles A45 to A415 and the straight line portion angles. Here, it is assumed that the differences between the angles A45 to A411 and the straight line portion angles do not exceed the allowable values, and the differences between the angles A412 to A415 and the straight line portion angles exceed the allowable values. Therefore, the straight line portion extraction unit 332 determines that the high-luminance points P12 to P15 are curved surface high-luminance points. The straight line portion extraction unit 332 extracts the high-luminance points P12 to P15 as curved surface high-luminance points. The curved surface high-luminance point extraction method shown in FIG. 8 makes it possible to accurately extract curved surface high-luminance points.

[0034] In this way, the straight line portion extraction unit 332 extracts the range of high luminance points P4 to P11, excluding the high luminance points P12 to P15, which are curved surface high luminance points, from among the high luminance points P4 to P15, which are workpiece high luminance points, as a straight line portion. Fig. 9 shows the straight line portions extracted by the straight line portion extraction unit 332. Fig. 9 shows not only the lines on which the high luminance points P4 to P11 are located, but also lines on which no peak luminance is extracted. Here, too, the number of lines is reduced from the actual number.

[0035] Even if the line laser light is irradiated so as to straddle the upper end of the die Td and the sheet metal W, the straight line portion extraction unit 332 excludes the die high brightness points from the high brightness points P1 to P15, and therefore can extract the straight line portion from the workpiece high brightness points.

[0036] As shown in Fig. 10, the straight line all pixel extraction unit 333 extracts all high-luminance points included in the straight line portion by extracting pixels having peak luminance on all lines that do not have pixels having peak luminance in the range of high-luminance points P4 to P11 extracted. As shown in Fig. 11, the straight line approximation unit 334 generates a straight line Ls by linearly approximating all high-luminance points included in the straight line portion shown in Fig. 10 using, for example, the least squares method. As shown in Fig. 12, the straight line angle calculation unit 335 calculates the image angle φ of the straight line Ls with respect to the horizontal direction.

[0037] The straight line approximation unit 334 may generate the straight line Ls by linearly approximating the high-luminance points P4 to P15 shown in Fig. 9 using the least squares method, instead of generating the straight line Ls based on all the high-luminance points included in the straight line portion shown in Fig. 10. It is not essential to provide the straight line all-pixel extraction unit 333. However, since the straight line approximation unit 334 can generate a more accurate straight line Ls by generating it based on all the high-luminance points included in the straight line portion, it is preferable to provide the straight line all-pixel extraction unit 333.

[0038] Returning to FIG. 3 , the image angle φ of the straight line Ls calculated by the image angle calculation unit 33 of the angle sensors 30F and 30R is transmitted to the bending angle conversion unit 22 of the angle sensor control device 20. The bending angle conversion unit 22 converts the two image angles φ calculated by the image angle calculation unit 33 of the angle sensors 30F and 30R into the bending angle θ of the sheet metal W shown in FIG. 2 and transmits it to the NC device 10. The NC device 10 compares the target bending angle with the bending angle θ, which is the measured actual bending angle of the sheet metal W bent to the target bending angle. Based on the comparison result, the NC device 10 can control the press brake main body 101 to bend the sheet metal W so as to further approach the target bending angle. Furthermore, the NC device 10 can control the press brake main body 101 to bend the sheet metal W so as to even closer to the target bending angle during subsequent bending processes of the sheet metal W.

[0039] As described above, the bend angle measuring device and bend angle measuring method according to one or more embodiments calculates the image angle φ based on the high-brightness points on the straight line portion of the workpiece high-brightness points, excluding the high-brightness points on the curved surface, and converts the image angle φ into the bend angle θ of the metal sheet W. Therefore, according to the bend angle measuring device and bend angle measuring method according to one or more embodiments, even if part of the surface of the front flange Wf or the rear flange Wr onto which the line laser light is irradiated is curved, it is possible to accurately measure the bend angle θ of the metal sheet W.

[0040] The method by which the straight line portion extraction unit 332 extracts the reference point (main reference point) of the workpiece high brightness point from among a plurality of high brightness points obtained by sampling a line image included in the image captured by the camera 35 is not limited to the method described in Figures 7A to 7D. The straight line portion extraction unit 332 may extract the main reference point by the method shown in Figure 13.

[0041] As shown in FIG. 13, the straight line segment extraction unit 332 sets, for example, the lowest high-luminance point P1 in frame F as a tentative reference point, and calculates the angle A12 between the high-luminance point P1 and the next higher high-luminance point P2. Next, the straight line segment extraction unit 332 calculates the angle A13 between the high-luminance point P1 and the next higher high-luminance point P3. Because the difference between angle A12 and angle A13 is within the tolerance, the straight line segment extraction unit 332 determines that the high-luminance point P3 is not the actual reference point for the workpiece high-luminance point. This tolerance does not need to be the same as the tolerance used in the method described with reference to FIGS. 7A to 7D.

[0042] Furthermore, the straight line portion extraction unit 332 calculates the angle A14 formed by the high luminance point P1 and the high luminance point P4. Because the difference between the angle A12 and the angle A14 exceeds the allowable value, the straight line portion extraction unit 332 determines that the high luminance point P4 and the high luminance points P5 to P15 located above it are workpiece high luminance points, and sets the high luminance point P4 as the main reference point.

[0043] The method of extracting the main reference points of the workpiece high-brightness points shown in Fig. 13 can be used when the line laser light is also irradiated onto the upper end of the die Td, and the high-brightness points obtained by sampling the line image included in the image captured by the camera 35 include the die high-brightness points. When the line laser light is not irradiated onto the upper end of the die Td, and is irradiated only onto the front flange Wf and the rear flange Wr, the method described with reference to Figs. 7A to 7D can be used.

[0044] When the straight line portion extraction unit 332 uses the method shown in FIG. 13, the straight line portion angle is not used, so the NC device 10 does not need to send the target bending angle to the angle sensor control device 20, and the angle sensor control device 20 does not need to send the straight line portion angle to the image angle calculation unit 33.

[0045] Furthermore, the method by which the straight-line segment extraction unit 332 extracts curved-surface high-brightness points from among the workpiece high-brightness points is not limited to the method described in FIG. 8. The straight-line segment extraction unit 332 calculates the difference between angle A45 and each of angles A46 to A415, such as the difference between angle A45 and angle A46, the difference between angle A45 and angle A47, the difference between angle A45 and angle A48, and so on. The high-brightness point at an angle where the difference exceeds the tolerance, i.e., the high-brightness point where the angle has changed beyond the tolerance, is the first high-brightness point among the curved-surface high-brightness points. The straight-line segment extraction unit 332 determines that high-brightness points P12 and subsequent points, which are high-brightness points at angles where the difference exceeds the tolerance, are curved-surface high-brightness points. The tolerance here does not need to be the same as the tolerance used in the method described in FIG. 8.

[0046] When the straight line portion extraction unit 332 uses a method of extracting the first high-brightness point on the curved surface depending on whether the angle changes beyond the allowable value, the straight line portion angle is not used. Therefore, the NC device 10 does not need to transmit the target bending angle to the angle sensor control device 20, and the angle sensor control device 20 does not need to transmit the straight line portion angle to the image angle calculation unit 33.

[0047] The operation of the bend angle measuring device according to one or more embodiments and the bend angle measuring method according to one or more embodiments will be further described using the flowchart shown in Figure 14. In Figure 14, when processing is started by turning on the power of the press brake 100, for example, the angle sensor control device 20 determines in step S1 whether a bend angle measurement request has been made from the NC device 10. If a bend angle measurement request has not been made from the NC device 10 (NO), the angle sensor control device 20 repeats the processing of step S1.

[0048] If a request to measure the bending angle is made from the NC device 10 in step S1 (YES), the angle sensor control device 20 instructs the angle sensor 30 to irradiate line laser light and capture an image in step S2. In step S3, the angle sensor 30 irradiates the metal sheet W with line laser light and captures the reflected light. In step S4, the image angle calculation unit 33 of the angle sensor 30 samples a line image included in the captured image. In step S5, the image angle calculation unit 33 sets the selected high-brightness point among the workpiece high-brightness points as the main reference point. The image angle calculation unit 33 may set the lowmost high-brightness point among the workpiece high-brightness points or a high-brightness point nearby as the main reference point.

[0049] In step S6, the image angle calculation unit 33 extracts straight line portions by excluding curved surface high-brightness points from the workpiece high-brightness points. In step S7, the image angle calculation unit 33 extracts all high-brightness points included in the straight line portions. In step S8, the image angle calculation unit 33 linearly approximates all high-brightness points. In step S9, the image angle calculation unit 33 calculates the image angle of the linearly approximated straight line. The image angle calculation unit 33 transmits the image angle to the angle sensor control device 20. In step S10, the bending angle conversion unit 22 converts the image angles obtained by the two angle sensors 30F and 30R into bending angles of the sheet metal W. In step S11, the angle sensor control device 20 transmits the bending angle to the NC device 10.

[0050] In step S12, the angle sensor control device 20 determines whether or not to terminate the operation of the bending angle measuring device by, for example, turning off the power to the press brake 100. If the operation is not to be terminated (NO), the bending angle measuring device repeats the processing from step S1 onwards. If the operation is to be terminated (YES), the bending angle measuring device terminates the processing.

[0051] In the configuration example of the bending angle measuring device shown in Fig. 3, an image angle calculation unit 33 is provided on a sensor substrate 31 in an angle sensor 30. The image angle calculation unit 33 may be provided in an angle sensor control device 20. Furthermore, a function similar to that of the angle sensor control device 20 may be provided in an NC device 10, or a function similar to that of the angle sensor control device 20 and the image angle calculation unit 33 may be provided in an NC device 10. The function of the operation instruction unit 32 may be provided in the NC device 10.

[0052] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0053] 1 Upper table 2 Upper mold holder 3 Lower table 4 Lower mold holder 5L,5R side plate 6L, 6R hydraulic cylinder 7 Operation pendant 8 Footswitch 10 NC device 20 Angle sensor control device 21 Straight section angle conversion section 22 Bending angle conversion section 30, 30F, 30R angle sensor 31 Sensor board 32 Operation instruction section 33 Image angle calculation unit 34 Laser diode (laser light irradiation part) 35 Camera 40 Backgauge 41 Backgauge carriage 42a, 42b butt 100 Press Brake 101 Press brake body Td die Tp Punch W Sheet metal (workpiece) Wf Front flange (first flange) Wr Rear flange (second flange)

Claims

1. a laser light irradiation unit that irradiates a linear laser light onto a first flange on a front side of the punch and the die and a second flange on a rear side of the punch and the die in a workpiece that is sandwiched between the punch and the die and bent to a target bending angle; a camera that captures the reflected light of the laser light irradiated onto the first and second flanges; an image angle calculation unit that extracts, as a straight line portion, a range of high-brightness points excluding high-brightness points irradiated onto an area where the first or second flange is a curved surface from among a plurality of high-brightness points obtained by sampling a line image due to the reflected light included in the image captured by the camera, and calculates an image angle of a straight line obtained by linearly approximating at least the sampled high-brightness points included in the straight line portion; a bending angle conversion unit that converts the image angle into a bending angle of the workpiece; Equipped with The image angle calculation unit a reference point is set to the lowest high-brightness point or a high-brightness point nearby among the high-brightness points based on the reflected light of the laser light irradiated on the first and second flanges, and angles formed between the reference point and each high-brightness point located above the reference point are calculated; The theoretical angle of a line image of the reflected light included in the photographed image, which is obtained by photographing the reflected light of the laser light irradiated on the first and second flanges of the workpiece bent to the target bending angle, is defined as a straight line angle, and a range of high brightness points in which the difference between the angle formed by the reference point and each high brightness point and the straight line angle exceeds an allowable value is excluded as high brightness points irradiated on an area where the first or second flange is a curved surface. Bending angle measuring device.

2. 2. The bending angle measurement device according to claim 1, wherein the image angle calculation unit extracts all high-brightness points included in the straight line portion, including unsampled high-brightness points included in the straight line portion, and calculates an image angle of a straight line obtained by linearly approximating all high-brightness points included in the straight line portion.

3. the laser light irradiation unit irradiates the first and second flanges with the laser light so that the upper end of the die is also irradiated with the laser light; The image angle calculation unit excludes high brightness points based on reflected light of the laser light irradiated to the die from the plurality of high brightness points obtained by sampling the line image included in the photographed image, and extracts the straight line portion from high brightness points based on reflected light of the laser light irradiated to the first and second flanges.

3. The bending angle measuring device according to claim 1 or 2.

4. A linear laser beam is irradiated onto a first flange on a front side of the punch and a second flange on a rear side of the punch and the die in a workpiece that is sandwiched between the punch and the die and bent to a target bending angle; Photographing the reflected light of the laser light irradiated on the first and second flanges with a camera; sampling a line image due to the reflected light included in the image captured by the camera to obtain a plurality of high-brightness points; a high-luminance point located at the bottom of the plurality of high-luminance points or a high-luminance point nearby the high-luminance point is set as a reference point, and angles formed between the reference point and each high-luminance point located above the reference point are calculated; a linear portion angle is defined as a theoretical angle of a line image of the reflected light included in a photographed image obtained by photographing with the camera the reflected light of the laser light irradiated onto the first and second flanges of the workpiece bent to the target bending angle, and a range of high-brightness points among the plurality of high-brightness points in which a difference between the angle formed by the reference point and each high-brightness point and the linear portion angle exceeds an allowable value is excluded as high-brightness points irradiated onto an area in which the first or second flange is a curved surface, and the high-brightness points are extracted as linear portions; generating a straight line by linearly approximating high-luminance points included in at least the straight line portion; Calculating an image angle of the straight line; The image angle is converted into a bending angle of the workpiece. Bending angle measurement method.

5. A bending angle measurement method as described in claim 4, which extracts all high-brightness points contained in the straight line portion, including unsampled high-brightness points contained in the straight line portion, and calculates the image angle of a straight line that is a linear approximation of all high-brightness points contained in the straight line portion.

Images