JP2007111703A - Apparatus for controlling die cushion mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for controlling a die cushion mechanism, wherein a work can be stably worked while abnormality caused upon the operation of a press machine is accurately detected so as to prevent the breakage of a die cushion. <P>SOLUTION: The apparatus (10) for controlling the die cushion mechanism comprises: a first force detection means (21a) of detecting force generated between a die cushion (20) and a slide (24); a second force detection means (21b) of detecting force generated between the die cushion and the slide; and an abnormality detection means (70) of detecting abnormality generated at the press machine. The abnormality detection means detects the fact that abnormality is generated at the press machine in the case the absolute value of the difference between the first force detected value (Dfa) detected by the first force detection means and the second force detected value (Dfb) detected by the second force detection means lies in a threshold or above. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a die cushion mechanism.

  In a press machine that performs press processing such as bending, drawing, and punching, a second die is attached to a movable side support member (generally referred to as a slide) that supports the first die used for press processing during the processing operation. It is known to equip a die cushion mechanism as an accessory device that applies a desired force (pressure) from the side of a supporting member (generally called a bolster) to be supported. A die cushion mechanism usually causes a movable element (called a die cushion) held at a predetermined pressure to directly or indirectly collide with a slide (or first mold) moving in the mold closing direction, and then closes the mold ( The cushion pad is configured to move with the slide while applying a force (pressure) to the slide until it reaches the mold opening after molding. In the meantime, for example, by pinching the peripheral area of the processing part of the workpiece to be processed between the cushion pad and the slide, it is possible to prevent wrinkles of the workpiece to be processed.

  If the force acting between the slide and the die cushion during operation of the press machine is too great than the desired force, a relatively large impact will be exerted between the first and second molds, so Product life may be reduced. On the other hand, when the force acting between the slide and the die cushion is too small than the desired force, there is a possibility that the workpiece is not sufficiently processed.

  In order to avoid such a problem, a force detection unit that detects a force acting between the slide and the die cushion is usually provided. Then, when the detection value detected by the force detection unit is larger than the predetermined upper limit value and smaller than the predetermined lower limit value, it is detected that there is an abnormality, and the die life is reduced and the processing defect is generated. It is preventing.

  However, when such a force detection unit fails for some reason, a force detection value that does not correspond to the force that actually acts between the slide and the die cushion is output from the force detection unit. However, even if the detected value does not correspond to the actual force, if the detected value is between the above-described upper limit value and lower limit value, it cannot be detected that an abnormality has occurred. In such a case, since the press machine operates as it is, there is a possibility that the mold life is shortened and a processing failure occurs.

  FIG. 17 is a functional block diagram of a conventional control device for a die cushion mechanism. The position control unit 920 of the control device 100 creates a position control speed command value Cv1 from the die cushion position command value and the detected value of the die cushion position used for position feedback. Further, the force control unit 940 creates a force control speed command value Cv2 from the force command value acting between the die cushion and the slide and the force detection value used for force feedback.

  Next, the position control speed command value Cv1 and the force control speed command value Cv2 are supplied to the comparison calculation unit 950. The comparison calculation unit 950 compares the downward magnitude of the position control speed command value Cv1 and the force control speed command value Cv2, that is, the magnitude of the speed in the direction in which the slide descends toward the cushion pad. . For example, when it is determined that the position control speed command value Cv1 is larger, the position control unit 920 controls the die cushion, and when the force control speed command value Cv2 is determined to be larger. The switching operation of the switching device 930 is performed so that the die cushion is controlled by the force control unit 940.

  However, when switching from position control to force control when the position control speed command value Cv1 and the force control speed command value Cv2 are not equal, the command value of the force acting between the die cushion and the slide and its detected value If the force deviation between the two is too large, the press machine will be impacted.

  Similarly, when switching from force control to position control when the position control speed command value Cv1 and the force control speed command value Cv2 are not equal, the position deviation between the command value of the die cushion position and its detected value is If it is too large, the press machine will be impacted.

  Further, when the absolute value of the difference between the position control speed command value Cv1 and the force control speed command value Cv2 is relatively large, the press machine is also subjected to an impact when switching between position control and force control. Can occur.

  Due to such an impact, the position of the work to be processed between the first and second molds is shifted, and as a result, stable processing of the work to be processed cannot be performed.

  The present invention has been made in view of such circumstances, and it is possible to accurately detect an abnormality that may occur during operation of a press machine to prevent damage to the die cushion and to stably process a workpiece. An object of the present invention is to provide a control device for a die cushion.

  In order to achieve the above-described object, according to a first invention, in a control device for a die cushion mechanism that generates a force against a slide of a press machine using a servomotor, A first force detecting means for detecting the force generated in the first, a second force detecting means for detecting the force generated between the die cushion and the slide, and an abnormality occurring in the press machine. An abnormality detection means for detecting the first force detection value detected by the first force detection means and the second force detection value detected by the second force detection means. There is provided a control device that detects an abnormality of the press machine when the absolute value of the difference between the two is greater than or equal to a threshold value.

  According to the second aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using the servo motor, the force that commands the force generated between the die cushion and the slide. Command means, first force detection means for detecting force generated between the die cushion and the slide, and second force for detecting force generated between the die cushion and the slide Based on the detection means, the force command value commanded by the force command means, and the first and second force detection values detected by the first and second force detection means, respectively, the force of the servo motor Force control speed command value creating means for creating a control speed command value, die cushion position command means for commanding the position of the die cushion, and detecting the position of the die cushion A position control speed of the servo motor based on the cushion position detection means, the die cushion position command value commanded by the die cushion position command means, and the die cushion position detection value detected by the die cushion position detection means; Position control speed command value creating means for creating a command value, force control speed command value created by the force control speed command value creating means, position control speed command value created by the position control speed command value creating means, A switching means for switching between the first force detection means and an abnormality detection means for detecting an abnormality occurring in the press machine, wherein the abnormality detection means includes the first force detection value detected by the first force detection means and the first force detection value. An abnormality of the press machine is detected when the absolute value of the difference between the second force detection value detected by the second force detection means is equal to or greater than a threshold value. A control device is provided in which the threshold value is different between when the switching means is switched to the force control speed command value and when the threshold value is switched to the position control speed command value. .

That is, in the first and second inventions, the absolute value of the difference between the detection values of the two force detection means is compared with a threshold value, so that if one of the force detection means fails, the absolute value of the difference Becomes greater than or equal to the threshold value, so that it is possible to accurately detect that an abnormality has occurred in the force detection means. Since the detection value detected by the force detection means is used for control of the press machine, if an abnormality occurs in the force detection means, the operation of the press machine is affected. That is, it is possible to accurately detect an abnormality that may occur during operation of the press machine by accurately detecting an abnormality that has occurred in the force detection means.
Furthermore, in the second aspect of the invention, different threshold values can be adopted when the position control speed command value is used and when the force control speed command value is used, so that an abnormality occurring in the press machine can be determined more precisely. .

  According to the third aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using a servo motor, the force generated between the die cushion and the slide is detected. A force detecting means; a collision detecting means for detecting the collision between the slide and the die cushion; and an abnormality detecting means for detecting an abnormality occurring in the press machine, and detected by the force detecting means. When the force detection value does not exceed the threshold value within a predetermined time after the collision detection by the collision detection means, a control device is provided in which the abnormality detection means detects an abnormality of the press machine.

  According to the fourth aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using the servo motor, the force generated between the die cushion and the slide is detected. A force detecting means; a collision detecting means for detecting the collision between the slide and the die cushion; and an abnormality detecting means for detecting an abnormality occurring in the press machine, and detected by the force detecting means. When the differential value of the force detection value does not exceed a threshold value within a predetermined time after the collision detection by the collision detection means, a control device is provided in which the abnormality detection means detects an abnormality of the press machine. The

  That is, in the third invention, since the force acting between the slide and the die cushion increases after the collision, if this force does not exceed the threshold value within a predetermined time, an abnormality has occurred in the force detection means. Can be detected. Since the detection value detected by the force detection means is used for control of the press machine, if an abnormality occurs in the force detection means, the operation of the press machine is affected. That is, it is possible to accurately detect an abnormality that may occur during operation of the press machine by accurately detecting an abnormality that has occurred in the force detection means.

  Note that, as in the fourth aspect of the invention, the abnormality may be detected by comparing the differential value of the force detection value detected by the force detection means with a threshold value.

  According to the fifth aspect of the present invention, in a control device for a die cushion mechanism that generates a force against a slide of a press machine using a servo motor, a force that commands a force generated between the die cushion and the slide. Command means, force detection means for detecting a force generated between the die cushion and the slide, a force command value commanded by the force command means, and a force detection value detected by the force detection means A force control speed command value creating means for creating a force control speed command value for the servo motor, a die cushion position command means for commanding the position of the die cushion, and a die cushion for detecting the position of the die cushion. Position detection means, die cushion position command value commanded by the die cushion position command means and die cushion position detection A position control speed command value creating means for creating a position control speed command value for the servo motor based on a die cushion position detection value detected by the step; and a force control speed created by the force control speed command value creating means. A switching means for switching the command value and the position control speed command value created by the position control speed command value creating means; and an abnormality detection means for detecting an abnormality occurring in the press machine. When switching from the position control speed command value to the force control speed command value, the force deviation between the force command value commanded by the force command means and the force detection value detected by the force detection means is greater than or equal to a threshold value. In some cases, a control device is provided in which the abnormality detection means detects an abnormality of the press machine.

  If the force deviation is relatively large when switching from the position control speed command value to the force control speed command value, an impact will occur on the press machine. In the fifth aspect of the invention, this force deviation is compared with a threshold value. Therefore, it is possible to accurately detect an abnormality that may occur during the operation of the press machine and prevent the occurrence of an impact.

  According to the sixth aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using a servo motor, a force that commands the force generated between the die cushion and the slide. Command means, force detection means for detecting a force generated between the die cushion and the slide, a force command value commanded by the force command means, and a force detection value detected by the force detection means A force control speed command value creating means for creating a force control speed command value for the servo motor, a die cushion position command means for commanding the position of the die cushion, and a die cushion for detecting the position of the die cushion. Position detection means, die cushion position command value commanded by the die cushion position command means and die cushion position detection A position control speed command value creating means for creating a position control speed command value for the servo motor based on a die cushion position detection value detected by the step; and a force control speed created by the force control speed command value creating means. A switching means for switching the command value and the position control speed command value created by the position control speed command value creating means; and an abnormality detection means for detecting an abnormality occurring in the press machine. When switching from the force control speed command value to the position control speed command value, the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means When the positional deviation between the two is greater than or equal to a threshold value, the abnormality detecting means detects an abnormality of the press machine. Your device is provided.

  If the position deviation is relatively large when switching from the force control speed command value to the position control speed command value, an impact will occur on the press machine. In the sixth aspect of the invention, this position deviation is compared with a threshold value. Therefore, it is possible to accurately detect an abnormality that may occur during the operation of the press machine and prevent the occurrence of an impact.

  According to the seventh aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using a servo motor, a force that commands the force generated between the die cushion and the slide. Command means, force detection means for detecting a force generated between the die cushion and the slide, a force command value commanded by the force command means, and a force detection value detected by the force detection means A force control speed command value creating means for creating a force control speed command value for the servo motor, a die cushion position command means for commanding the position of the die cushion, and a die cushion for detecting the position of the die cushion. Position detection means, die cushion position command value commanded by the die cushion position command means and die cushion position detection A position control speed command value creating means for creating a position control speed command value for the servo motor based on a die cushion position detection value detected by the step; and a force control speed created by the force control speed command value creating means. A switching means for switching the command value and the position control speed command value created by the position control speed command value creating means; and an abnormality detection means for detecting an abnormality occurring in the press machine. If the absolute value of the difference between the position control speed command value and the force control speed command value is greater than or equal to a threshold when switching from the position control speed command value to the force control speed command value, the abnormality detection A control device is provided in which means detects an abnormality of the press machine.

  According to the eighth aspect of the invention, in the control device for the die cushion mechanism that generates a force against the slide of the press machine using a servo motor, a force that commands the force generated between the die cushion and the slide. Command means, force detection means for detecting a force generated between the die cushion and the slide, a force command value commanded by the force command means, and a force detection value detected by the force detection means A force control speed command value creating means for creating a force control speed command value for the servo motor, a die cushion position command means for commanding the position of the die cushion, and a die cushion for detecting the position of the die cushion. Position detection means, die cushion position command value commanded by the die cushion position command means and die cushion position detection A position control speed command value creating means for creating a position control speed command value for the servo motor based on a die cushion position detection value detected by the step; and a force control speed created by the force control speed command value creating means. A switching means for switching the command value and the position control speed command value created by the position control speed command value creating means; and an abnormality detection means for detecting an abnormality occurring in the press machine. When the absolute value of the difference between the position control speed command value and the force control speed command value is greater than or equal to a threshold value when switching from the force control speed command value to the position control speed command value, the abnormality detection A control device is provided in which means detects an abnormality of the press machine.

  When the switching means switches between the position control speed command value and the force control speed command value, if the difference between these speed command values is relatively large, the press machine is impacted, but the seventh and eighth In this invention, since this difference is compared with a threshold value, an abnormality that may occur during the operation of the press machine can be accurately detected.

  In the first to eighth inventions described above, since an abnormality that may occur during the operation of the press machine is accurately detected, the die cushion can be prevented from being damaged and the workpiece can be processed stably.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a schematic diagram showing a basic configuration of a die cushion mechanism 20 of a press machine provided with a control device 10 according to the present invention, and the press machine is in an open state. As shown in FIG. 1, two support portions 12 extend in the vertical direction from the base 11, and flat plate bolsters 15 are disposed at the tips of the support portions 12 via dampers 13, respectively. In FIG. 1, a die cushion mechanism 20 is provided below the bolster 15.

  The slide 24 supports a first die 26 used for press working. A ball screw device 33 is connected to the slide 24 on the side opposite to the side supporting the first mold 26. The ball screw device 33 is connected to the output shaft of the first servo motor 38 via a belt / pulley device 34. With such a mechanism, the slide 24 moves toward or away from the second die 27 supported by the bolster 15 at a speed required for pressing.

  The die cushion mechanism 20 according to the present invention includes a cushion pad 16 that slides in a direction perpendicular to the lower surface of the bolster 15 in response to the operation of the slide 24, and a second servomotor 18 that raises and lowers the cushion pad 16. It is out. A plurality of cushion pins 31 extending from the top surface of the cushion pad 16 protrude from the bolster 15 through the holes of the bolster 15. The workpiece 35 is supported at the tip of the cushion pin 31.

  The cushion pad 16 is disposed in association with the second mold 27 and is connected to the output shaft of the second servomotor 18 via the ball screw device 17. The slide 24 (or the first mold 26) directly or indirectly collides with the cushion pad 16 waiting at a predetermined position while moving in the mold closing direction. Normally, the cushion pad 16 is configured to move together with the slide 24 while applying a required force (pressure) F to the slide 24 until the mold is opened after the mold is closed (molded). In the present specification, the cushion pad 16 and members related thereto are appropriately referred to as a die cushion.

  Such an operation is performed by the control device 10 of the press machine according to the present invention. During the operation of the press machine, the first servo motor 38 is rotated by the control device 10 and the slide 24 is lowered. For this reason, the first mold 26 presses the plurality of cushion pins 31 via the workpiece 35. Thereby, the cushion pad 16 is pushed downward.

  On the other hand, the second servo motor 18 is rotated by the control device 10 so as to lower the cushion pad 16 in accordance with the lowering operation of the cushion pad 16. When the force (pressure) acting on the cushion pad 16 is increased, the cushion pin 31 is further lowered, and the workpiece 35 is gripped between the first die 26 of the slide 24 and the second die 27 of the bolster 15 and pressed. Processed. At this time, the bolster 15 is slightly lowered by the slide 24. Next, when the slide 24 reaches its bottom dead center, the slide 24 starts to rise, the other members return to their initial positions, and the press work is finished.

  As described above, the control device 10 controls the first servo motor 38 and the second servo motor 18 to generate a relative pressure (ie, force F) between the cushion pad 16 and the slide 24. As can be seen from FIG. 1, a first force detection unit 21 a and a second force detection unit 21 b that detect this pressure (that is, force F) are connected to the control device 10. These force detectors 21a and 21b are arranged below the cushion pad 16, and each detects a pressure (ie, force F). A speed detector 32 that detects the rotational speed of the first servo motor 38 as the speed Dv ′ of the slide 24 is connected to the control device 10. Similarly, a speed detection unit 22 that detects the rotation speed of the second servomotor 18 as the die cushion speed detection value Dv is also connected to the control device 10. These speed detectors 22 and 32 are used for feedback control of the slide speed and the die cushion speed, respectively.

  As shown in FIG. 1, the position detection unit 25 is disposed adjacent to the support unit 12, and this position detection unit 25 is also connected to the control device 10. The position detector 25 can detect the vertical position of the die cushion 20, particularly the vertical position of the cushion pad 16, and can also detect the position of the slide 24. That is, the position detection unit 25 can serve as a die cushion position detection unit and a slide position detection unit. The force detectors 21a and 21b can employ known force sensors, the speed detectors 22 and 32 can employ known encoders, and the position detector 25 can employ known linear scales.

  In an embodiment not shown, a dedicated position detector (not shown) for detecting the vertical position of the die cushion and a dedicated position detector (not shown) for detecting the vertical position of the slide 24 are separately provided. You may make it provide.

  FIG. 2 is a functional block diagram showing a control device for a die cushion mechanism based on the first and second embodiments of the present invention. As shown in FIG. 2, the control device 10 according to the first and second embodiments includes a position control unit 92 and a force control unit 94.

  As illustrated, the position control unit 92 is connected to a die cushion position command unit 61 that commands a die cushion position command value Cx and a die cushion position detection unit 25 that detects a die cushion position detection value Dx. The position control unit 92 creates a position control speed command value Cv1 from the die cushion position command value Cx and the die cushion position detection value Dx used for position feedback.

  Further, the force control unit 94 detects a force command unit 62 that commands a force command value Cf of the force F acting between the die cushion 20 and the slide 24, and detects force detection values Dfa and Dfb of the force F, respectively. The first force detector 21a and the second force detector 21b are connected. The force control unit 94 creates a force control speed command value Cv2 from the force command value Cf and the force detection value Dfa or Dfb used for force feedback. The position control speed command value Cv1 and the force control speed command value Cv2 are speed command values related to the rotation speed of the second servomotor 18.

  As illustrated, the position control speed command value Cv 1 and the force control speed command value Cv 2 are input to the comparison calculation unit 95. The comparison calculation unit 95 compares the downward magnitude of the position control speed command value Cv1 and the force control speed command value Cv2, that is, the magnitude of the speed in the direction in which the slide descends toward the cushion pad. . For example, when it is determined that the position control speed command value Cv1 is larger, the comparison operation unit 95 switches so that the position control speed command value Cv1 of the position control unit 92 is selected.

  On the other hand, when it is determined that the force control speed command value Cv2 is larger, the comparison operation unit 95 switches so that the force control speed command value Cv2 of the force control unit 94 is selected. That is, the comparison calculation unit 95 serves as switching means for switching between the position control speed command value Cv1 and the force control speed command value Cv2. Although not shown in the drawings, the control device 10 may be provided with a switching device 930 similar to the prior art, and the switching operation may be performed by the switching device.

  One of the selected position control speed command value Cv <b> 1 and force control speed command value Cv <b> 2 is input to the current command generation unit 65 of the control device 10 through the comparison calculation unit 95. The current command creation unit 65 has a function of creating a current command value Ci of the second servomotor 18 based on one of the position control speed command value Cv1 and the force control speed command value Cv2 and the die cushion speed detection value Dv. I have.

  The current command value Ci is obtained in advance by experiments or the like as a function f of one of the position control speed command value Cv1 and the force control speed command value Cv2 and, for example, the die cushion speed detection value Dv. It is assumed that it is stored in 10 storage units (not shown). The current command value Ci by the current command creation unit 65 may be obtained from such a map, or may be calculated based on a predetermined calculation formula. The storage unit of the control device 10 stores a threshold value, a reference value, and the like used in the operation program in addition to the operation program described later.

  The control device 10 further includes an abnormality detection unit 70 that detects an abnormality that has occurred in the press machine. As illustrated, the force detection values Dfa and Dfb detected by the first force detection unit 21a and the second force detection unit 21b are supplied to the abnormality detection unit 70. Further, the abnormality detection unit 70 is connected to the current command generation unit 65 so that an abnormality signal indicating that an abnormality has occurred can be output to the current command generation unit 65. When an abnormality signal is output from the abnormality detection unit 70, predetermined processing at the time of abnormality detection is performed. For example, it is assumed that the current command value Ci is created using a map at the time of detecting an abnormality instead of the map at the time of normal control described above.

  The operation of the die cushion mechanism according to the first embodiment of the present invention will be described below with reference to FIG. In steps 101 and 102 of the operation program 110, the force detection value Dfa from the first force detection unit 21a and the force detection value Dfb from the second force detection unit 21b are read. Next, in step 103, the absolute value ΔDf (= | Dfa−Dfb |) of the difference between the force detection values Dfa and Dfb is calculated.

  Next, at step 104, it is determined whether or not the difference ΔDf is greater than or equal to a predetermined threshold value ΔDf0. If the difference ΔDf is not equal to or greater than the predetermined threshold value ΔDf0, it is determined that the difference is normal, normal control is performed (step 105), and the process is repeated (see “RETURN” in the drawing).

  On the other hand, when the difference ΔDf is equal to or greater than the predetermined threshold value ΔDf0, it is considered that one of the first force detection unit 21a and the second force detection unit 21b has failed and cannot output proper detection values Dfa and Dfb. It is done. Since the detection values Dfa and Dfb detected by the force detection units 21a and 21b are used for controlling the press machine, if an abnormality occurs in the force detection means, the operation of the press machine is affected. Accordingly, in such a case, it is determined in step 106 that an abnormality has occurred in the press machine. Next, in step 107, the processing at the time of abnormality detection described above is performed, and then the processing is repeated.

  That is, in the first embodiment of the present invention, by providing the first force detection unit 21a and the second force detection unit 21b, it is possible to accurately detect a case where one of the force detection units fails. The present invention may be configured to include three or more force detection units, and the abnormality may be determined through the absolute value of the difference between the force detection values detected by any two of these force detection units.

  FIG. 4 is a flowchart showing the operation of the die cushion mechanism according to the second embodiment of the present invention. Steps 201 to 203 of the operation program 200 shown in FIG. 4 are the same as steps 101 to 103 of the control device 100, and thus description thereof is omitted.

  In step 204, it is determined whether or not the current control is force control, that is, whether or not the force control speed command value Cv2 by the force control unit 94 is used. In the case of force control, the routine proceeds to step 206, where it is determined whether or not the difference ΔDf is greater than or equal to a predetermined threshold value ΔDf02. When the difference ΔDf is greater than or equal to the threshold value ΔDf02, an abnormality is determined in the same manner as described above, and processing when an abnormality is detected is performed (steps 207 and 208). If the difference ΔDf is not greater than or equal to the threshold value ΔDf02, normality is determined and normal control is performed (step 209).

  On the other hand, if it is determined in step 204 that it is not force control, that is, position control, that is, if it is determined that the position control speed command value Cv1 by the position control unit 92 is used, the process proceeds to step 205. It is determined whether the difference ΔDf is greater than or equal to a predetermined threshold value ΔDf01. This threshold value ΔDf01 is different from the threshold value ΔDf02, and these threshold values are values optimized for force control and position control, respectively.

  If the difference ΔDf is greater than or equal to a predetermined threshold value ΔDf01, an abnormality is determined, and processing when an abnormality is detected is performed (steps 210 and 211). If the difference ΔDf is not greater than or equal to the threshold value ΔDf01, normality is determined and normal control is performed (step 209). Thus, in the second embodiment, different threshold values ΔDf01 and ΔDf02 are used for position control and force control. Therefore, in addition to the same effects as those obtained in the case of the first embodiment, it is possible to perform more appropriate abnormality determination at the time of each control.

  By the way, since the die cushion 20 receives force from the slide 24 at the time of force control, the first force detection unit 21a is more than the second force detection unit 21b depending on the place where the first force detection unit 21a is installed. May receive power. For this reason, the threshold value ΔDf02 is set to a relatively large value including an extra force.

  On the other hand, since the die cushion 20 is separated from the slide 24 during position control, no force is generated between them. Therefore, the threshold value ΔDf01 used at the time of position control does not need to take extra force into consideration, and as a result, the threshold value ΔDf01 may be smaller than the threshold value ΔDf02. In other words, by adopting a threshold value ΔDf01 that is smaller than the threshold value ΔDf02 during position control, it is possible to more accurately determine an abnormality that occurs in the press machine.

  FIG. 5 is a functional block diagram showing a control device for the die cushion mechanism according to the third and fourth embodiments of the present invention. In the first and second embodiments, two or more force detection units are used, but in the following embodiments, a single force detection unit may be used. For this reason, in the drawing, the first force detection unit 21a is shown as a representative, and the force detection value detected by the first force detection unit 21a is indicated by a force detection value Df.

  In the embodiment shown in FIG. 5, the first force detection unit 21 a and the abnormality detection unit 70 are connected, and the force detection value Df is supplied to the abnormality detection unit 70. Further, as shown in the figure, the force detection value Df may be supplied to the abnormality detection unit 70 as a force differential value d (Df) via a differentiation circuit 75 provided in the control device 10.

  The control device 10 further includes a collision detection unit 66 that determines whether or not the slide 24 and the die cushion 20 collide, and a timer 67 that measures an elapsed time T after the collision. As shown in the figure, the collision detection unit 66 and the timer 67 are connected to the abnormality detection unit 70.

  FIG. 6 is a flowchart showing the operation of the die cushion mechanism according to the third embodiment of the present invention. In step 301 of the operation program 300 shown in FIG. 6, the force detection value Df from the first force detection unit 21a is read. Next, at step 302, it is determined whether or not a collision between the slide 24 and the die cushion 20 is detected by the collision detection unit 66. A collision determination method by the collision detection unit 66 will be described later.

  If it is determined that the slide 24 and the die cushion 20 collide, the process proceeds to step 303. Then, an elapsed time T after the slide 24 and the die cushion 20 collide is read from the timer 67. Next, in step 304, it is determined whether or not the elapsed time T is within a predetermined threshold T0.

  When the elapsed time T is within the predetermined threshold T0, the routine proceeds to step 305, where it is determined whether or not the force detection value Df read at step 301 is greater than or equal to the predetermined threshold Df0. If the force detection value Df is greater than or equal to the predetermined threshold value Df0, a threshold value exceeding flag indicating that the force detection value Df is greater than or equal to the predetermined threshold value Df0 is set in step 307.

  On the other hand, if the force detection value Df is not equal to or greater than the predetermined threshold value Df0, no flag is set as shown in step 306. Similarly, when the collision between the slide 24 and the die cushion 20 is not detected in step 302, the threshold value exceeding flag is not set.

  Thereafter, the routine proceeds to step 309, where it is determined whether or not the slide 24 and the die cushion 20 are separated from each other. For this determination, the position of the slide 24 and the position of the die cushion 20 detected by the position detection unit 25 are appropriately used. If the slide 24 and the die cushion 20 are separated from each other, in step 310, a pre-collision state in which the slide 24 and the die cushion 20 do not collide is set. In step 310, the threshold value exceeding flag is cleared at the same time. Next, normal determination is made in step 311 and normal control is performed, and then the processing is repeated. In step 309, if the slide 24 and the die cushion 20 are not separated from each other, the process proceeds to step 311 and the process is repeated. Note that the threshold crossing flag is not cleared in this case.

  If it is determined in step 304 that the elapsed time T has exceeded the predetermined threshold value T0, it is determined in step 308 whether or not a threshold value exceeding flag is set. If the threshold exceeded flag is set, the process proceeds to step 309 as it is.

  On the other hand, when the threshold value exceeding flag is not raised, the force detection value Df does not exceed the threshold value Df0 within the predetermined time T0. In other words, the average increase rate of the force at the predetermined time T0 is smaller than the predetermined increase rate. Normally, the force acting between the slide 24 and the die cushion 20 at the time of collision increases with the passage of time. Therefore, if NO is determined in step 308, that is, the force detection value Df is within the predetermined time T0, the threshold value Df0 is set. If not, it can be determined that there is an abnormality in the first force detector 21a that has output the force detection value Df (step 312).

  As described above, the detection value Df detected by the force detection unit 21a is used for control of the press machine. Therefore, when an abnormality occurs in the force detection means, the operation of the press machine is affected. Therefore, in such a case, it can be determined that an abnormality has occurred in the press machine. In this case, in step 313, processing at the time of abnormality detection is performed.

  FIG. 7 is a flowchart showing the operation of the die cushion mechanism according to the fourth embodiment of the present invention. Steps 401 to 404 and 406 to 413 of the operation program 400 shown in FIG. 7 are the same as steps 301 to 304 and 306 to 313 of the operation program 300 shown in FIG.

  In the fourth embodiment, in step 404 ′, the force detection value Df is differentiated by the differentiating circuit 75 to calculate a differential value d (Df) of the force detection value Df. Next, in step 405, it is compared whether or not the differential value d (Df) is equal to or greater than a predetermined threshold value d (Df0). The differential value d (Df) of the force detection value Df calculated in step 404 'directly represents the increasing speed of the force generated at the time of collision. Therefore, in the fourth embodiment in which the differential value d (Df) of the force detection value Df is compared, a more strict determination is possible than in the case of the third embodiment.

  The collision detection unit 66 used in the third and fourth embodiments includes a slide position command unit 71 for commanding the vertical position Cy of the slide 24, as shown in FIG. 8 which is a functional block diagram thereof. A die cushion position command unit 61 that commands the vertical position Cx of the die cushion, a slide position detection unit 25 that detects the vertical position Dy of the slide, and a die cushion position detection unit that detects the vertical position Dx of the die cushion 25 and a force detection unit 21a that detects a detection value Df of the force F. The slide position command value Cy, the die cushion position command value Cx, the slide position detection value Dy, the die cushion position detection value Dx, and the force detection value Df are input to the collision detection unit 66.

  The collision determination of the collision detection unit 66 will be described with reference to FIGS. 9A to 9C which are flowcharts showing the operation of the collision detection unit. As shown in FIG. 9A, when the slide position command value Cy and the die cushion position command value Cx are always compared, and the slide position command value Cy and the die cushion position command value Cx are equal to each other. It can be determined (step 122) that the die cushion 20 and the slide 24 have collided with each other (step 121).

  Further, as shown in FIG. 9B, the slide position detection value Dy and the die cushion position detection value Dx are always compared, and the slide position detection value Dy and the die cushion position detection value Dx are equal to each other. (Step 131), it may be determined that the die cushion 20 and the slide 24 have collided (step 132).

  Furthermore, as shown in FIG. 9C, when the force detection value Df is larger than the predetermined value Df0 ′ by comparing the force detection value Df with the predetermined value Df0 ′ (step 141), It may be determined that the die cushion 20 and the slide 24 have collided (step 142). Any of the collision determination methods shown in FIGS. 9 (a) to 9 (c) may be adopted to determine the collision, or another collision determination method (not shown) may be employed.

  FIG. 10 is a functional block diagram showing a control device for a die cushion mechanism according to the fifth embodiment of the present invention. In the force control unit 94 shown in detail in FIG. 10, the difference between the force command value Cf commanded by the force command unit 62 and the force detection value Df detected by the force detection unit 21a, that is, the force deviation Δf ( = Cf−Df) is calculated. Next, a force control speed command value Cv2 is output by multiplying the force deviation Δf by a force gain Gf. Further, as shown in the figure, in the fifth embodiment, the force deviation Δf is supplied to the abnormality detection unit 70.

  FIG. 11 is a flowchart showing the operation of the die cushion mechanism according to the fifth embodiment of the present invention. In step 501 of the operation program 500 in FIG. 11, it is determined whether or not the current control is force control. If the current control is force control, normal determination is made and normal control is performed (step 504), and the process is repeated.

  If the current control is not force control, that is, if it is position control, the process proceeds to step 502. In step 502, it is determined whether or not switching from position control to force control is performed. If such switching is not performed, the process proceeds to step 504.

  On the other hand, when switching from position control to force control is performed, the routine proceeds to step 503, where it is determined whether or not the force deviation Δf is greater than or equal to a predetermined threshold value Δf0. If the force deviation Δf is greater than or equal to the threshold value Δf0, an abnormality is determined and processing at the time of abnormality detection is performed (steps 505 and 506). If the force deviation Δf is greater than or equal to a predetermined threshold value Δf0, an impact may occur at the time of switching, but in the present embodiment, the force deviation Δf is compared with the threshold value Δf0, which occurs during operation of the press machine. It is possible to accurately detect a possible abnormality and prevent the occurrence of an impact in advance.

  FIG. 12 is a functional block diagram showing a control device for a die cushion mechanism based on the sixth embodiment of the present invention. In the position control unit 92 shown in detail in FIG. 12, between the die cushion position command value Cx commanded by the die cushion position command unit 61 and the die cushion position detection value Dx detected by the die cushion position detection unit 25. Difference, that is, position deviation Δx (= Cx−Dx) is calculated. Next, the position control speed command value Cv1 is output by multiplying the position deviation Δx by the position gain Gx. As shown in the figure, in the sixth embodiment, the position deviation Δx is supplied to the abnormality detection unit 70.

  FIG. 13 is a flowchart showing the operation of the die cushion mechanism according to the sixth embodiment of the present invention. In step 601 of the operation program 600 in FIG. 13, it is determined whether or not the current control is force control. If the current control is not force control, that is, position control, normal determination is made and normal control is performed (step 604), and the process is repeated.

  If the current control is force control, the process proceeds to step 602. In step 602, it is determined whether or not switching from force control to position control is performed. If such switching is not performed, the process proceeds to step 604.

  On the other hand, when switching from force control to position control is performed, the routine proceeds to step 603, where it is determined whether or not the position deviation Δx is greater than or equal to a predetermined threshold value Δx0. When the position deviation Δx is greater than or equal to the threshold value Δx0, an abnormality is determined and processing at the time of abnormality detection is performed (steps 605 and 606). If the position deviation Δx is equal to or greater than the predetermined threshold value Δx0, an impact may occur at the time of switching. In this embodiment, however, the positional deviation Δx is generated during operation of the press machine by comparing the position deviation Δx with the threshold value Δx0. It is possible to accurately detect a possible abnormality and prevent the occurrence of an impact in advance.

  FIG. 14 is a functional block diagram showing a control device for a die cushion mechanism based on the seventh and eighth embodiments of the present invention. In these embodiments, the position control speed command value Cv1 created by the position control unit 92 and the force control speed command value Cv2 created by the force control unit 94 are supplied to the abnormality detection unit 70.

  FIG. 15 is a flowchart showing the operation of the die cushion mechanism according to the seventh embodiment of the present invention. In step 701 of the operation program 700 in FIG. 15, it is determined whether or not the current control is force control. If the current control is force control, normal determination is made and normal control is performed (step 705), and the process is repeated.

  If the current control is not force control, that is, if it is position control, the process proceeds to step 702. In step 702, it is determined whether or not switching from position control to force control is performed. If such switching is not performed, the process proceeds to step 705.

  On the other hand, when switching from position control to force control is performed, the routine proceeds to step 703, where the absolute value of the difference between the position control speed command value Cv1 and the force control speed command value Cv2 | Cv1-Cv2 | ( = ΔCv) is calculated. The speed command value difference ΔCv is created in the abnormality detection unit 70.

  Next, the routine proceeds to step 703, where it is determined whether or not the speed command value difference ΔCv is greater than or equal to a predetermined threshold value ΔCv01 (step 704). If the speed command value difference ΔCv is greater than or equal to the threshold value ΔCv01, an abnormality is determined, and processing when an abnormality is detected is performed (steps 706 and 707). When the speed command value difference ΔCv is greater than or equal to a predetermined threshold value ΔCv01, there is a possibility that an impact may occur at the time of switching. It is possible to accurately detect an anomaly that may occur during the operation and prevent the occurrence of an impact in advance. If the speed command value difference ΔCv is greater than or equal to the predetermined threshold value ΔCv01 in step 704, the process proceeds to step 705 and normal control is performed.

  FIG. 16 is a flowchart showing the operation of the die cushion mechanism according to the eighth embodiment of the present invention. In step 801 of the operation program 800 in FIG. 16, it is determined whether or not the current control is force control. If the current control is not force control, that is, position control, normal determination is made and normal control is performed (step 805), and the process is repeated.

  If the current control is force control, the process proceeds to step 802. In step 802, it is determined whether or not switching from position control to force control is performed. If such switching is not performed, the process proceeds to step 805.

  On the other hand, when switching from position control to force control is performed, the routine proceeds to step 803 where the absolute value of the difference between the position control speed command value Cv1 and the force control speed command value Cv2 | Cv1-Cv2 | ( = ΔCv) is similarly calculated.

  Next, the routine proceeds to step 803, where it is determined whether or not the speed command value difference ΔCv is greater than or equal to a predetermined threshold value ΔCv02 (step 804). If the speed command value difference ΔCv is greater than or equal to the threshold value ΔCv02, an abnormality is determined and processing upon abnormality detection is performed (steps 806 and 807). When the speed command value difference ΔCv is greater than or equal to a predetermined threshold value ΔCv02, there is a possibility that an impact may occur at the time of switching. It is possible to accurately detect an anomaly that may occur during the operation and prevent the occurrence of an impact in advance. If the speed command value difference ΔCv is greater than or equal to the predetermined threshold value ΔCv02 in step 804, the process proceeds to step 805 and normal control is performed.

  Combining some of the embodiments described above as appropriate is within the scope of the present invention.

It is a schematic diagram which shows the basic composition of the die cushion mechanism of the press machine provided with the control apparatus based on this invention. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 1st and 2nd embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 1st embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 2nd embodiment of this invention. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 3rd and 4th embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 3rd embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 4th embodiment of this invention. It is a functional block diagram which shows the detail of a collision detection part. (A) It is a flowchart which shows operation | movement of a collision detection part. (B) It is another flowchart which shows operation | movement of a collision detection part. (C) It is another flowchart which shows operation | movement of a collision detection part. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 5th embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 5th embodiment of this invention. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 6th embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 6th Embodiment of this invention. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 7th and 8th embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 7th embodiment of this invention. It is a flowchart which shows operation | movement of the die cushion mechanism based on 8th embodiment of this invention. It is a functional block diagram of the control apparatus of the die cushion mechanism of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control apparatus 18 2nd servomotor 20 Die cushion 21a 1st force detection part 21b 2nd force detection part 22, 32 Speed detection part 24 Slide 25 Slide position detection part, Die cushion position detection part 35 Workpiece | work 38 1st servo Motor 61 Die cushion position command section 62 Force command section 65 Current command creation section 66 Collision detection section 67 Timer 70 Abnormality detection section 71 Slide position command section 75 Differentiation circuit 92 Position control section 94 Force control section 95 Comparison calculation section Cf Force command value Ci Current command value Cv1 Position control speed command value Cv2 Force control speed command value Cx Die cushion position command value Cy Slide position command value d (Df) Differential value Df Force detection value Dfa, Dfb Force detection value Dv Die cushion speed detection value Dx Die cushion position detection value Dy Slide position detection value Elapsed time T0 predetermined time ΔCv speed command value difference ΔDf force detection value of the difference Δf force deviation Δx position deviation ΔDf0, ΔDf01, ΔDf02, Df0, d (Df0), Δf0, Δx0, ΔCv01, ΔCv02 threshold

Claims (8)

In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
First force detection means for detecting a force generated between the die cushion and the slide;
Second force detection means for detecting a force generated between the die cushion and the slide;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
The abnormality detection means has an absolute value of a difference between the first force detection value detected by the first force detection means and the second force detection value detected by the second force detection means. A control device that detects an abnormality of the press machine when the value is equal to or greater than a threshold value. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force command means for commanding a force generated between the die cushion and the slide;
First force detection means for detecting a force generated between the die cushion and the slide;
Second force detection means for detecting a force generated between the die cushion and the slide;
Based on the force command value commanded by the force command means and the first and second force detection values detected by the first and second force detection means, respectively, the force control speed command value of the servo motor Force control speed command value creating means for creating
Die cushion position command means for commanding the position of the die cushion;
Die cushion position detecting means for detecting the position of the die cushion;
Position control for creating a position control speed command value for the servo motor based on the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means Speed command value creation means;
Switching means for switching between the force control speed command value created by the force control speed command value creation means and the position control speed command value created by the position control speed command value creation means;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
The abnormality detection means has an absolute value of a difference between the first force detection value detected by the first force detection means and the second force detection value detected by the second force detection means. It is designed to detect abnormalities in the press machine when the threshold value is exceeded,
The control device in which the threshold value is different between when the switching means is switched to the force control speed command value and when the threshold value is switched to the position control speed command value. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force detecting means for detecting a force generated between the die cushion and the slide;
A collision detection means for detecting the collision between the slide and the die cushion;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
When the force detection value detected by the force detection means does not exceed a threshold value within a predetermined time from the time of collision detection by the collision detection means, the abnormality detection means detects an abnormality of the press machine. Control device. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force detecting means for detecting a force generated between the die cushion and the slide;
A collision detection means for detecting the collision between the slide and the die cushion;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
If the differential value of the force detection value detected by the force detection means does not exceed a threshold value within a predetermined time after the collision detection by the collision detection means, the abnormality detection means detects an abnormality of the press machine. Control device. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force command means for commanding a force generated between the die cushion and the slide;
Force detecting means for detecting a force generated between the die cushion and the slide;
Force control speed command value creating means for creating a force control speed command value for the servo motor based on the force command value commanded by the force command means and the force detection value detected by the force detection means;
Die cushion position command means for commanding the position of the die cushion;
Die cushion position detecting means for detecting the position of the die cushion;
Position control for creating a position control speed command value for the servo motor based on the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means Speed command value creation means;
Switching means for switching between the force control speed command value created by the force control speed command value creation means and the position control speed command value created by the position control speed command value creation means;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
When the switching means switches from the position control speed command value to the force control speed command value, the force between the force command value commanded by the force command means and the force detection value detected by the force detection means. A control device in which the abnormality detecting means detects an abnormality of the press machine when the deviation is equal to or greater than a threshold value. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force command means for commanding a force generated between the die cushion and the slide;
Force detecting means for detecting a force generated between the die cushion and the slide;
Force control speed command value creating means for creating a force control speed command value for the servo motor based on the force command value commanded by the force command means and the force detection value detected by the force detection means;
Die cushion position command means for commanding the position of the die cushion;
Die cushion position detecting means for detecting the position of the die cushion;
Position control for creating a position control speed command value for the servo motor based on the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means Speed command value creation means;
Switching means for switching between the force control speed command value created by the force control speed command value creation means and the position control speed command value created by the position control speed command value creation means;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
When switching from the force control speed command value to the position control speed command value by the switching means, the die cushion position command value commanded by the die cushion position command means and the die cushion detected by the die cushion position detection means A control apparatus in which the abnormality detecting means detects an abnormality of the press machine when a positional deviation between the position detection value and the position detection value is equal to or greater than a threshold value. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force command means for commanding a force generated between the die cushion and the slide;
Force detecting means for detecting a force generated between the die cushion and the slide;
Force control speed command value creating means for creating a force control speed command value for the servo motor based on the force command value commanded by the force command means and the force detection value detected by the force detection means;
Die cushion position command means for commanding the position of the die cushion;
Die cushion position detecting means for detecting the position of the die cushion;
Position control for creating a position control speed command value for the servo motor based on the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means Speed command value creation means;
Switching means for switching between the force control speed command value created by the force control speed command value creation means and the position control speed command value created by the position control speed command value creation means;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
When the switching means switches from the position control speed command value to the force control speed command value, and the absolute value of the difference between the position control speed command value and the force control speed command value is greater than or equal to a threshold value. Is a control device in which the abnormality detecting means detects an abnormality of the press machine. In the control device of the die cushion mechanism that generates a force against the slide of the press machine using a servo motor,
Force command means for commanding a force generated between the die cushion and the slide;
Force detecting means for detecting a force generated between the die cushion and the slide;
Force control speed command value creating means for creating a force control speed command value for the servo motor based on the force command value commanded by the force command means and the force detection value detected by the force detection means;
Die cushion position command means for commanding the position of the die cushion;
Die cushion position detecting means for detecting the position of the die cushion;
Position control for creating a position control speed command value for the servo motor based on the die cushion position command value commanded by the die cushion position command means and the die cushion position detection value detected by the die cushion position detection means Speed command value creation means;
Switching means for switching between the force control speed command value created by the force control speed command value creation means and the position control speed command value created by the position control speed command value creation means;
An abnormality detecting means for detecting an abnormality occurring in the press machine,
When the switching means switches from the force control speed command value to the position control speed command value when the absolute value of the difference between the position control speed command value and the force control speed command value is equal to or greater than a threshold value. Is a control device in which the abnormality detecting means detects an abnormality of the press machine.

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