Punching device

Abstract

The present invention provides a punching device capable of detecting foreign matter with higher accuracy than the prior art. The punching device is used for punching processing, which uses a die composed of a die with a hole of a predetermined shape and a punch composed of a die of a predetermined shape to punch a workpiece into a predetermined shape, and the punching device also includes: load sensors, which are respectively arranged at positions in the punching device to which the force applied to the die is transmitted, and measure the load in the punching direction of each of at least three different predetermined points in the die; and a control device, which calculates a first moment and a second moment, and determines that foreign matter has been generated when the magnitude of at least one of the first moment and the second moment deviates from the range of a predetermined value, with respect to a first axis and a second axis on a plane perpendicular to the punching direction, the first moment is the sum of the moments of the measured load around the first axis, and the second moment is the sum of the moments of the measured load around the second axis.

Description

Technical Field

[0001] The present invention relates to a punching device for shearing a workpiece such as metal using a die, and more particularly to a punching device capable of detecting the generation of foreign matter. Background Art

[0002] In the past, in the blanking process of shearing the workpiece with a die and a punch, foreign matter mixed between the die and the punch, or between the punch and the workpiece has become a major factor in processing abnormalities and has therefore become a problem. In particular, it is widely known that the phenomenon called "waste floating" is a phenomenon in which waste of the workpiece generated during blanking is mixed between the die and the punch, or between the punch and the workpiece as foreign matter as the punch rises, and causes product defects and mold damage.

[0003] The punching device of patent document 1 is provided with a plurality of distance sensors around the die, and the plurality of distance sensors detect the distance between the upper die including the punch and the lower die including the die, and when the relationship between the detected values ​​does not satisfy the prescribed reference, it is judged that foreign matter is mixed between the punch and the workpiece, and the abnormality is output to be detected by the operator, and the operation of the punching device is automatically stopped.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 7-164075 Summary of the invention

[0007] A punching device according to one embodiment of the present invention is used for punching work, in which a workpiece is punched into a predetermined shape using a die formed of a die having a hole of a predetermined shape and a punch formed of a die of a predetermined shape.

[0008] The punching device also has:

[0009] load sensors are respectively arranged at positions in the punching device to which the force applied to the die is transmitted, and measure the load in the punching direction at each of at least three predetermined points different from each other in the die; and

[0010] A control device calculates a first moment and a second moment, and determines that foreign matter has been generated when the magnitude of at least one of the first moment and the second moment deviates from a specified value range, wherein the first moment is the sum of the moments of the measured load around the first axis and the second moment is the sum of the moments of the measured load around the second axis with respect to the first axis and the second axis on a plane perpendicular to the punching direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram showing a configuration example of the punching device according to the first embodiment.

[0012] Figure 2A It is shown Figure 1 A side view of an example of a detailed structure of a die of a punching device.

[0013] Figure 2B It is shown Figure 1 A three-dimensional diagram of a detailed structural example of a die of a punching device.

[0014] Figure 3 It is shown Figure 1 A top view of an example of the configuration of load sensors in a punching device.

[0015] Figure 4A It is shown in Figure 1 A side view of an operation example of a punching device in which foreign matter is generated on a workpiece.

[0016] Figure 4B It is shown in Figure 1 A side view of an operation example in which a foreign matter is generated on the side of a workpiece in a punching device.

[0017] Figure 5A It is shown in Figure 1 A three-dimensional diagram showing an example of force and torque during foreign matter detection operation in a punching device.

[0018] Figure 5B It is shown in Figure 1 A front view of a display example of a display device during a foreign matter detection operation in a punching device.

[0019] Figure 6 It is shown in Figure 1 FIG. 4 is a diagram showing an example of a display of a setting screen for a foreign matter detection threshold value in a punching device.

[0020] Figure 7 It is shown in Figure 1 Figure 2 is a diagram showing an example of a foreign matter detection action result table in a punching device.

[0021] Description of Reference Numerals

[0022] 1 Punch

[0023] 2 Punch base

[0024] 3 Punch retainer

[0025] 4 Ejector spring

[0026] 5. Demoulding device

[0027] 6 Stripper guide

[0028] 7 Die

[0029] 8 Die base

[0030] 9 Die Cage

[0031] 11 upper backing plate

[0032] 12 Bottom plate

[0033] 121 Hole (of lower plate)

[0034] 122 Blanking shaft

[0035] 13 Linear guides

[0036] 21 Workpiece

[0037] 22 Foreign matter

[0038] 31 Mould

[0039] 32 upper mold

[0040] 33 Lower die

[0041] 34. Demolder unit

[0042] 35, 351~354 Load sensor

[0043] 36 Load Amplifier

[0044] 37 Computer

[0045] 38 Display device

[0046] 51 Punching device

[0047] 52 Servo Motor

[0048] 53 Top Plate

[0049] 54 Sliding Plate

[0050] 55 Base plate

[0051] 56 Slide bar

[0052] 57 Ball Screw

[0053] 58 Control device. DETAILED DESCRIPTION

[0054] In the punching device of Patent Document 1, when foreign matter represented by the above-mentioned punching waste is generated on the side of the workpiece without overlapping with the workpiece, the distance between the upper die and the lower die does not change, so the foreign matter cannot be detected. In addition, in the punching device of Patent Document 1, when the upper die also has a structure of a demolding device that presses the workpiece before punching, if the punching cycle is shortened (made high speed), sometimes due to the rebound of the demolding device, etc., even if there is no foreign matter, the change in distance will be detected. Such erroneous detection will hinder the continuous punching process and reduce the working efficiency, so it is not preferred.

[0055] The present invention solves the above-mentioned problems and provides a punching device capable of detecting foreign matter with higher accuracy than the conventional technology.

[0056] A punching device according to a first aspect of the present invention is used for punching work, in which a workpiece is punched into a predetermined shape using a die formed of a die having a hole of a predetermined shape and a punch formed of a die of a predetermined shape.

[0057] The punching device also has:

[0058] load sensors are respectively arranged at positions in the punching device to which the force applied to the die is transmitted, and measure the load in the punching direction at each of at least three predetermined points different from each other in the die; and

[0059] A control device calculates a first moment and a second moment, and determines that foreign matter has been generated when the magnitude of at least one of the first moment and the second moment deviates from a specified value range, wherein the first moment is the sum of the moments of the measured load around the first axis and the second moment is the sum of the moments of the measured load around the second axis with respect to the first axis and the second axis on a plane perpendicular to the punching direction.

[0060] A second punching device according to the present invention is the first device, wherein the first axis and the second axis are perpendicular to each other at the center of the hole of the die.

[0061] The punching device of the third scheme of the present invention can be based on the above-mentioned first scheme or second scheme, and the range of the specified value is a range of values ​​with a amplitude of positive and negative specified values ​​based on the value of the first initial torque and the value of the second initial torque. The first initial torque is the first torque pre-measured when no foreign matter is generated, and the second initial torque is the second torque pre-measured when no foreign matter is generated.

[0062] The punching device of the fourth scheme of the present invention can be based on any one of the above-mentioned first to third schemes, and can also be that when the control device determines that foreign matter has been generated, it can estimate in which quadrant of the four quadrants divided by the first axis and the second axis the foreign matter has been generated based on the size relationship between the size of the first torque and the size of the first initial torque and the size relationship between the size of the second torque and the size of the second initial torque, and provide it to the user via the output device.

[0063] A punching device according to a fifth aspect of the present invention may be any one of the first to fourth aspects, and further include a stripper that presses and holds the workpiece before the punching process.

[0064] In a punching device according to a sixth aspect of the present invention, in any one of the first to fifth aspects, the control device may stop the punching process of the punching device when determining that a foreign object has been generated.

[0065] According to the punching device of the present invention, foreign matter can be detected with higher accuracy than in the prior art.

[0066] Hereinafter, the punching device of Embodiment 1 will be described with reference to the accompanying drawings. It should be noted that in the accompanying drawings, substantially the same components are marked with the same reference numerals. In addition, components that are not necessary to explain the embodiments may be omitted unless otherwise specified.

[0067] [Implementation Method 1]

[0068] Figure 1 1 is a block diagram showing a configuration example of a punching device 51 according to Embodiment 1 of the present invention. Figure 1 In the figure, the punching device 51 includes a servo motor 52, a top plate 53, a sliding plate 54, a base plate 55, a sliding rod 56, a ball screw 57, a control device 58, a die 31, multiple load sensors 35, a load amplifier 36, a computer 37 and a display device 38.

[0069] exist Figure 1 In the embodiment, the servo motor 52 is disposed on the top plate 53 and is rotated by being driven and controlled by the control device 58. The ball screw 57 converts the rotation of the servo motor 52 into a linear movement, and moves the slide plate 54 up and down along the slide rod 56.

[0070] The die 31 includes an upper die 32 and a lower die 33. The lower die 33 is fixed to a base plate 55. The upper die 32 is fixed to a slide plate 54 and moves up and down with the movement of the slide plate 54. The workpiece 21 is sandwiched between the lower die 33 and the upper die 32 moving downward to perform the punching process. The detailed structure of the die 31 will be described later.

[0071] Four load sensors 35 are arranged on the lower die 33. The load sensors 35 measure the load applied to the lower die 33 and output a load signal indicating the measured load to the load amplifier 36. The load amplifier 36 amplifies the input load signal into an amplified load signal and outputs the amplified load signal to the computer 37. The computer 37 determines whether there is a foreign object 22 inside the die 31 based on the input amplified load signal. When the computer 37 determines that there is a foreign object 22, it controls the control device 58 to stop the punching process, or notifies the operator of the generation of the foreign object 22 via the display device 38. When the computer 37 determines that there is a foreign object 22, it may also control the control device 58 to stop the punching process, and notify the operator of the generation of the foreign object 22 via the display device 38.

[0072] Figure 2A It is shown Figure 1 A side view of a detailed structural example of the mold 31. In addition, Figure 2B It is shown Figure 1 A three-dimensional diagram of a detailed structural example of the mold 31.

[0073] exist Figure 2A In the embodiment, the die 31 includes an upper pad 11, a lower pad 12, a linear guide 13, an upper die 32, a lower die 33, and a stripper section 34. The upper die 32 includes a punch 1, a punch base 2 for fixing the punch 1, and a punch holder 3. The lower die 33 includes a die 7, a die base 8 for fixing the die 7, and a die holder 9. The stripper section 34 is composed of a stripper spring 4, a stripper 5, and a stripper guide 6.

[0074] The upper die 32 moves up and down by being fixed to an upper pad that moves up and down along the linear guide 13. A hole of any predetermined shape, such as a circle or a polygon, is formed in the die 7. In addition, the punch 1 has a columnar shape of the same shape. By sandwiching a workpiece 21 (not shown) between the die 7 and the punch 1 and moving the upper die 32 downward in such a manner that the punch 1 is introduced into the hole of the die 7, a hole in the shape of the punch 1 can be punched out in the workpiece 21.

[0075] The stripper 5 of the stripper portion 34 is arranged so that the lower surface is located below the front end of the punch 1. The stripper 5 can move in the up-down direction along the stripper guide 6. The stripper 5 comes into contact with the workpiece 21 before the punch 1 as the upper die 32 moves downward, and presses and holds the workpiece 21 during the punching process under the elastic force of the stripper spring 4.

[0076] Four load sensors 35 are arranged between the lower surface of the die base 8 and the upper surface of the lower pad 12. The detailed arrangement of the load sensors 35 will be described later. The load sensors 35 measure the load applied to the die 7 during the punching process and output a load signal indicating the measured load to the load amplifier 36.

[0077] Figure 3 It is shown Figure 1 A top view of an example of the configuration of the load sensor 35 of the punching device 51. Figure 3 In FIG. 1 , the paper surface shows the upper surface of the bottom plate 12. Elements other than the bottom plate 12 and the load sensor 35 that are not necessary for explanation are omitted.

[0078] exist Figure 3 In this embodiment, four load sensors 35, namely, load sensors 351 to 354, are arranged in the punching device 51. The load sensors 351 to 354 are arranged symmetrically about the X-axis and the Y-axis with respect to the XY plane having the center of the hole 121 of the die 7, namely, the punching axis 122 as the origin. Specifically, the load sensors 351 to 354 are arranged in sequence at four points whose coordinates on the XY plane are (a, -b), (-a, -b), (-a, b), and (a, b) for the lengths a and b.

[0079] The loads in the punching direction applied to the load sensors 351 to 354 are represented by Fz1 to Fz4, respectively. At this time, the total punching load Fz, the moment Mx about the X axis, and the moment My about the Y axis are represented by the following equations, respectively.

[0080] Fz=Fz1+Fz2+Fz3+Fz4

[0081] Mx=b(-Fz1-Fz2+Fz3+Fz4) (1)

[0082] My=a(-Fz1+Fz2+Fz3-Fz4) (2)

[0083] The moment Mx about the X-axis is processed as positive in the clockwise direction relative to the positive direction of the X-axis, and the moment My about the Y-axis is processed as positive in the clockwise direction relative to the positive direction of the Y-axis.

[0084] It should be noted that, when the load sensors 351 to 354 are not arranged symmetrically with respect to the X-axis and the Y-axis, the mathematical formula of the moment becomes more complicated. In order to stably support the die base 8, the load sensors 351 to 354 are also preferably arranged symmetrically.

[0085] For the punching device 51 constructed as described above, the following is used Figure 4A to Figure 7 Let's explain its foreign body detection action.

[0086] In the present embodiment, the punching waste generated by the phenomenon of "waste floating" is assumed to be the foreign matter 22. Waste floating is a phenomenon in which the punching waste generated during the punching process adheres to the punch 1 under the action of electrostatic force, surface tension, etc., and detaches from the punch 1 after the punching process is completed, thereby being generated as a foreign matter 22 on the workpiece 21 or the die 7. Waste floating is particularly generated when the workpiece 21 is a thin plate with a thickness of less than 0.1 mm, for example, or when punching a small hole with a small punching shape. The reason is believed to be that the mass of the punching waste generated is small, so the punching waste is easily attached to the punch 1 under the action of the surface tension of the lubricating oil, magnetic force, electrostatic force, etc.

[0087] Figure 4A It is a side view showing an appearance example in the case where a foreign object 22 is generated on the upper surface of the workpiece 21. Since the foreign object 22 is generated on the upper surface on the negative side of the X-axis of the workpiece 21, the ejector 5 that presses the workpiece 21 does not contact the workpiece 21 but contacts the foreign object 22 above it. Among the ejector springs 4 connected to the ejector 5, the ejector spring 4 in the negative direction of the X-axis contracts more than the ejector spring 4 in the positive direction of the X-axis by an amount corresponding to the thickness of the foreign object 22. Therefore, the load in the blanking direction applied by the ejector 5 to the die 7 becomes greater toward the negative side of the X-axis. In addition, due to the generation of the foreign object 22, as Figure 4A As shown by the arrow, the center of gravity of the object placed on the die 7 is biased toward the negative direction of the X-axis. Therefore, for the load in the blanking direction applied to the die 7 by the workpiece 21 and the foreign matter 22, the side in the negative direction of the X-axis (Fz2, Fz3) is greater than the side in the positive direction (Fzl, Fz4).

[0088] Figure 4B 2 is a side view showing an example of the appearance when the foreign matter 22 is directly generated on the side of the workpiece 21, that is, on the die 7. Figure 4A Unlike the case of the stripper 5, the stripper 5 is in horizontal contact with the workpiece 21, so there is no load offset caused by the stripper spring 4. On the other hand, since the foreign matter 22 is generated on the negative side of the X-axis of the workpiece 21, Figure 4A Likewise, if Figure 4B As shown by the arrow, the center of gravity of the object placed on the die 7 is biased toward the negative direction of the X-axis, so that the load (Fz2, Fz3) on the negative side of the X-axis is greater than that on the positive side (Fzl, Fz4).

[0089] The values ​​of the measured loads Fz1 to Fz4 of the load sensors 351 to 354 are output as load signals indicating the measured loads Fz1 to Fz4 to the load amplifier 36 . The load amplifier 36 amplifies the load signals into amplified load signals and outputs the amplified load signals to the computer 37 .

[0090] Figure 5A 2 is a diagram showing the relationship between the loads Fz1 to Fz4 and the moments Mx and My about the X-axis and the Y-axis when the foreign matter 22 is generated without overlapping the workpiece 21. Figure 5A In the figure, the moments Mx and My of the load around the X-axis and Y-axis are respectively indicated by the arrows in the figure, with the clockwise direction relative to each axis being positive. Assuming that no foreign matter 22 is generated, the measured loads Fz1 to Fz4 of the load sensors 351 to 354 symmetrically arranged relative to the X-axis and the Y-axis are all the same value. Therefore, if the moments Mx and My are calculated according to equations (1) and (2), Mx = 0 and My = 0 are essentially established. Such moments Mx and My in the case where no foreign matter 22 is generated are called initial moments Mx0 and My0.

[0091] Here, in Figure 5A In the above, consider the case where the foreign matter 22 is generated without overlapping the workpiece 21 in the region (first quadrant) where both the X and Y coordinates of the die 7 are positive. Figure 4B As described above, the position of the center of gravity of the object placed on the die 7 is biased toward the side of the foreign matter 22, so the load applied to the load sensors 351 to 354 becomes larger as it approaches the side where the foreign matter 22 is generated. Therefore, the measured load Fz4 of the load sensor 354 located on the foreign matter 22 side with respect to the X-axis becomes larger than the measured load Fz1 of the load sensor 351 located on the opposite side, and similarly, the measured load Fz3 of the load sensor 353 becomes larger than the measured load Fz2 of the load sensor 352. In addition, with respect to the Y-axis, the measured load Fz4 becomes larger than the measured load Fz3, and the measured load Fz1 becomes larger than the measured load Fz2.

[0092] When the moments Mx and My are calculated according to equations (1) and (2) using these measured loads Fz1 to Fz4, Mx>0 and My<0 are satisfied. When at least one of the moments Mx and My is not zero, the computer 37 determines that the foreign matter 22 has occurred.

[0093] Here, consider the case where the foreign matter 22 is generated in other quadrants of the die 7. When the foreign matter 22 is generated in the second quadrant of the die 7 (the region where the X coordinate is negative and the Y coordinate is positive), the measured load Fz3 becomes larger and the measured load Fzl becomes smaller. Therefore, if the moments Mx and My are calculated based on equations (1) and (2), Mx>0 and My>0 hold. Similarly, when the foreign matter 22 is generated in the third quadrant of the die 7 (the region where both the X coordinate and the Y coordinate are negative), Mx<0 and My>0 are obtained. When the foreign matter 22 is generated in the fourth quadrant of the die 7 (the X coordinate is positive and the Y coordinate is negative), Mx<0 and My<0 are obtained. Therefore, by confirming the positive and negative moments Mx and My around the X axis and the Y axis, it is possible to estimate in which quadrant of the die 7 the foreign matter 22 is generated.

[0094] The computer 37 that determines that the foreign object 22 has been generated estimates in which quadrant the foreign object 22 has been generated as described above, and controls the display device 38 to display Figure 5B The operator is warned by the screen 380 shown, and the control device 58 is controlled to stop the operation of the punching device 51. The screen 380 displays the frames corresponding to the first to fourth quadrants of the die 7, and the frame corresponding to the quadrant where the foreign matter 22 is estimated to have been generated is displayed in a warning color different from other frames. By viewing the screen 380, the operator can confirm in which quadrant of the die 7 the foreign matter 22 has been generated, and remove the foreign matter 22.

[0095] It should be noted that in the present embodiment, the moments about the X-axis and the Y-axis are used to estimate in which of the four regions divided by the X-axis and the Y-axis the foreign matter 22 is generated. However, as long as there are at least three load sensors 35, the purpose of estimating the position of the foreign matter 22 can be achieved. However, if more load sensors are used, in addition to improving the detection accuracy of the foreign matter 22, the region of the die 7 can be divided into more regions, thereby estimating a more detailed position of the foreign matter 22.

[0096] In addition, Figure 5B In the embodiment, the display device 38 is, for example, a display device such as a liquid crystal display. However, any display device may be used as long as the operator can be informed of which area of ​​the plurality of areas divided by the area of ​​the die 7 has produced the foreign matter 22. For example, the four LED lights arranged on the punching device 51 may be used to inform the operator of the location where the foreign matter 22 has been produced.

[0097] Figure 61 is a front view showing an example of a display of a setting screen for determining the generation of foreign matter. In the step of determining that the above-mentioned foreign matter 22 has been generated, when the values ​​of the moments Mx and My are not 0, it can be considered that a slight measurement error or a swing is mistakenly detected as the generation of the foreign matter 22. Therefore, the punching device 51 in this embodiment determines that the foreign matter 22 has been generated when at least one of the absolute values ​​of the moments Mx and My is greater than a predetermined threshold value. This threshold value can be set by, for example, prompting the operator. Figure 6 The screen shown in the figure is displayed, and the operator is prompted to input and set the threshold values ​​for the moments Mx and My.

[0098] It should be noted that, since the initial moments Mx0 and My0 are 0 in the present embodiment, the quadrant of the die 7 where the foreign matter 22 has been generated can be estimated based on the positive and negative values ​​of the moments Mx and My. However, sometimes the initial moments Mx0 and My0 are not 0 due to the number and location of the load sensors 35. In this case, the same estimation can be performed based on the magnitude relationship between the moments Mx and My and the initial moments Mx0 and My0. In this case, the threshold value of the moment Mx is not set for the absolute value |Mx| of the moment Mx, but the absolute value |Mx-Mx0| of the difference between the moment Mx and the initial moment Mx0 is set. In addition, it is also possible to set the upper limit and the lower limit separately, and when the magnitude of the moment Mx exceeds the range of the value, it is judged that the foreign matter 22 has been generated. This is also the same for the moment My.

[0099] In addition, in the present embodiment, when the absolute value of the moment Mx, My exceeds the threshold value, it is determined that the foreign matter 22 has been generated, and a warning is displayed on the display device 38, and the control device 58 is controlled to stop the punching device 51. However, other threshold values ​​may be set for the display of the warning and the stop of the punching device 51. For example, a warning may be displayed when the absolute value of the moment Mx exceeds 1.0 m·N, and the punching device 51 may be stopped when it exceeds 2.0 m·N.

[0100] Figure 7 is a table showing an example of the operation of the punching device 51. Figure 7 In Figure 6The threshold value shown is set as a threshold value for determining the generation of foreign matter 22. "Number of punching times" indicates the number of times the workpiece 21 is punched. The value in the "Torque difference" column indicates the difference between the moment Mx, My and the initial moment Mx0, My0. "Determination" indicates whether any of the above-mentioned moment differences related to the X and Y axes exceeds the threshold value, that is, the determination result indicating whether a foreign matter 22 has been generated. "NG" indicates the case where the moment difference exceeds the threshold value, and "OK" indicates the case where the threshold value is not exceeded. "Response" indicates the response automatically performed by the punching device 51 upon receiving the above-mentioned determination result.

[0101] exist Figure 7 In the first punching, the torque difference value did not exceed the threshold value, so it was determined that no foreign matter 22 was generated, and the punching process was continued in this state. In the second punching, the torque difference value related to the Y axis exceeded the threshold value, and it was determined that a foreign matter 22 was generated. Therefore, based on the signs of the torque differences related to the X and Y axes, respectively, a warning is displayed to the operator, and the punching process is stopped.

[0102] After that, the operator receives the warning and removes the foreign matter 22, and then restarts the punching device 51 to perform the third punching. In the third punching, the torque difference value does not exceed the threshold value, and it is determined that no foreign matter 22 is generated, and the punching process is continued.

[0103] In this way, the punching device 51 of the present embodiment measures the load applied to the die 7 using the load sensors 351 to 354, and calculates the moments Mx and My based on the measured loads Fz1 to Fz4. Thereafter, it is determined whether the foreign matter 22 has been generated based on the difference between the calculated moments Mx and My and the initial moments Mx0 and My0. When the foreign matter 22 has been generated, the punching device 51 displays the determination result including the quadrant of the die 7 where the foreign matter 22 has been generated to the operator, or stops the punching process of the punching device 51. It should be noted that, when the foreign matter 22 has been generated, the punching device 51 may display the determination result including the quadrant of the die 7 where the foreign matter 22 has been generated to the operator, and stop the punching process of the punching device 51. Thus, even when the foreign matter 22 has been generated in a place that does not overlap with the workpiece 21, the generation of the foreign matter 22 can be detected and the punching process can be stopped. Furthermore, by knowing in advance where the foreign matter 22 is generated, the operator can smoothly remove the foreign matter 22 and resume the next punching process.

[0104] It should be noted that in this embodiment, the punching waste generated by "waste floating" is assumed to be the foreign matter 22, but the punching device 51 is not limited to being able to detect the waste floating, and can also detect the mixing of foreign matter from the outside, etc. In addition, at least two of the load amplifier 36, computer 37, display device 38, control device 58, etc. in this embodiment can also be configured as the same element.

[0105] In the present embodiment, the load sensor 35 is disposed under the die base 8 , but it may be disposed at any position in the die to which the loads applied to three or more points are transmitted. For example, a plurality of load sensors 35 may be disposed in the stripper portion 34 .

[0106] [Industrial Applicability]

[0107] The punching device of the present invention can detect foreign matter even when the distance between the demolding device and the lower die does not change, such as when the foreign matter is left on the side of the workpiece, and the punching processing cycle is accelerated. Although the detection sensitivity is high, the number of false detections is small. Therefore, a punching device capable of high-precision foreign matter detection without reducing the productivity of the punching operation can be provided. The punching device of the present invention can also be applied to the punching processing of films and composite materials.

Claims

1. A punching device, wherein: The punching device is used for punching processing, wherein a workpiece is punched into the prescribed shape using a die formed by a die having a hole of a prescribed shape and a punch formed by the die of the prescribed shape. The punching device also includes: load sensors are respectively arranged at positions in the punching device to which the force applied to the die is transmitted, and measure the load in the punching direction at each of at least three predetermined points different from each other in the die; as well as A control device that calculates a first moment and a second moment, and determines that foreign matter has been generated when the magnitude of at least one of the first moment and the second moment deviates from a specified value range, wherein the first moment is the sum of the measured moments of the load around the first axis and the second moment is the sum of the measured moments of the load around the second axis with respect to a first axis and a second axis on a plane perpendicular to the punching direction.

2. The punching device according to claim 1, wherein: The first axis and the second axis are orthogonal at the center of the hole of the die.

3. The punching device according to claim 1 or 2, wherein: The range of the specified value is a range of values ​​with a amplitude of plus or minus the specified value based on the value of the magnitude of the first initial moment and the value of the magnitude of the second initial moment, wherein the first initial moment is the first moment measured in advance when no foreign matter is generated, and the second initial moment is the second moment measured in advance when no foreign matter is generated.

4. The punching device according to claim 3, wherein: The punching device further includes an output device configured to provide various information to a user. When the control device determines that the foreign object has been generated, based on the magnitude relationship between the magnitude of the first torque and the magnitude of the first initial torque and the magnitude relationship between the magnitude of the second torque and the magnitude of the second initial torque, it estimates in which quadrant of the four quadrants divided by the first axis and the second axis the foreign object has been generated, and provides the information to the user via the output device.

5. The punching device according to any one of claims 1 to 4, wherein: The punching device further includes a stripper that presses and holds the workpiece before the punching process.

6. The punching device according to any one of claims 1 to 5, wherein: The control device stops the punching process of the punching device when it is determined that the foreign matter has been generated.

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