JP4824463B2 - Control device for die cushion mechanism - Google Patents

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 collides a movable element (generally referred to as a cushion pad) held at a predetermined pressure with a slide (or first mold) moving in a mold closing direction directly or indirectly, and then a mold. The cushion pad is configured to move with the slide while applying a force (pressure) to the slide until the mold is opened after closing (molding). During this time, for example, by pinching the peripheral region of the processed portion of the workpiece material between the cushion pad and the slide, generation of wrinkles of the workpiece material can be prevented.

In the die cushion control device disclosed in Patent Document 1, oil is supplied to the lower oil chamber of the cylinder using a hydraulic accumulator, thereby raising the die cushion connected to the piston in the cylinder and the piston. . Further, by adjusting the relief valve, the oil in the lower oil chamber is discharged while exhibiting the cushion effect, thereby lowering the die cushion. In addition, a servo valve provided separately reduces the cushioning force at the end of the stroke.
JP-A-63-63533

  However, in the conventional die cushion control device as disclosed in Patent Document 1, the relief valve or the servo valve is often controlled by simple sequence control. In such a case, these valves cannot be controlled at high speed and with high accuracy, and therefore it is difficult to raise and lower the die cushion smoothly.

  Further, in Patent Document 1, the drive source differs between when the die cushion is raised and when it is lowered, which also hinders the valve from being controlled at high speed and with high accuracy.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a control device for a die cushion mechanism capable of smoothly operating the die cushion.

  In order to achieve the above-described object, according to the first invention, there is provided a control device for a die cushion mechanism that generates a force against a slide of a press machine using a servo motor as a drive source, and commands the speed of the servo motor. A speed command means; a speed detection means for detecting the speed of the servo motor; and a switching means for switching the rise and fall of the die cushion, wherein the switching means is the servo motor created by the speed command means. There is provided a control device for a die cushion mechanism that operates based on a change in a sign of a speed command or a change in a sign of a detected speed of the servo motor detected by the speed detecting means.

  That is, in the first invention, the switching means is operated based on the change in the speed of the servo motor, that is, the speed command or the sign of the detected speed. That is, when the sign changes from plus to minus or from minus to plus, the switching of the die cushion is switched by the switching means. For this reason, the switching means can be controlled at high speed and with high accuracy, and the operation of the die cushion becomes smooth. Note that the switching means is, for example, a switching valve, but other switching means that can switch the rising and lowering of the die cushion may be used.

According to the second invention, in the first invention, even if the speed command or the sign of the detected speed is changed, the detected speed detected by the speed detecting means is zero or less than a predetermined value. The switching means is not operated until it becomes smaller.
When the switching operation is performed immediately after the sign is changed, an impact can occur in the die cushion. Therefore, in the second invention, such an impact can be prevented from occurring.

According to a third invention, in the first invention, when the speed command is within a predetermined range when the sign of the speed command or the detected speed is changed, the speed command is set to zero. A different predetermined value was maintained.
Normally, when the sign of the speed command changes, the actual speed of the servo motor once becomes zero. However, in the third invention, the actual speed of the servo motor never becomes zero. It becomes possible. A positive predetermined value is used when the speed command is greater than or equal to zero, and a negative predetermined value is used when the speed command is less than zero.

According to a fourth invention, in the first invention, when the speed command is zero or within a predetermined range when the sign of the speed command or the detected speed changes, the die The switching means is controlled so that the cushion does not rise and fall.
When the speed command is zero or within a predetermined range and is relatively small, the switching means may malfunction due to the influence of noise. However, in the fourth invention, the switching means is substantially stopped. , Malfunction of the switching means can be avoided.

According to a fifth invention, in the first invention, when the speed command or the sign of the detected speed changes, the die cushion does not rise and fall until the detected speed falls within a predetermined range. The switching means is controlled as follows.
That is, in the fifth aspect, the control effect equivalent to that the actual speed of the servo motor is quickly made zero can be realized by stopping the switching means, and as a result, the die cushion can be controlled more quickly.

According to a sixth aspect, in the first aspect, when the speed command or the sign of the detected speed changes, the speed command of the code after the change is changed until the detected speed falls within a predetermined range. To be used.
That is, in the sixth aspect, a relatively large torque command can be generated by using the speed command after the sign change, and the actual speed of the servo motor can be quickly made zero. As a result, the die cushion can be controlled more quickly.

According to a seventh invention, in any one of the first to sixth inventions, the invention further comprises a prediction means for predicting a future speed command created by the speed command means, and is predicted by the prediction means. The sign of the speed command is used as the sign of the speed command created by the speed command means, thereby operating the switching means.
According to an eighth invention, in any one of the first to sixth inventions, the invention further comprises a prediction means for predicting a future speed command created by the speed command means, and is predicted by the prediction means. The speed command was used at the same time as the sign of the speed command created by the speed command means and the speed command used for speed control of the servo motor.
According to a ninth invention, in any one of the first to sixth inventions, the invention further comprises a prediction means for predicting a future speed command created by the speed command means, and is predicted by the prediction means. The speed command is used only as the servo motor speed command, and the switching means is operated with the sign of the speed command before prediction.
That is, in the seventh to ninth inventions, the die cushion mechanism can be controlled more quickly by using a future speed command. By using the speed command predicted by the prediction means as only the speed command used for the servo motor speed control, it is possible to realize the effect of matching the timing of the control of the switching means and the speed control of the servo motor. As the prediction means, the rate of change immediately before the speed command may be used, and a high-pass filter may be adopted as the prediction means.

According to a tenth invention, in any one of the first to sixth inventions, the invention further comprises a prediction means for predicting a future detection speed detected by the speed detection means, and is predicted by the prediction means. The sign of the detected speed is used as the sign of the detected speed detected by the speed detecting means, thereby operating the switching means.
That is, in the tenth invention, the die cushion mechanism can be controlled at a higher speed by using the future detection speed. Note that the predicting means may use the rate of change immediately before the speed command, and may employ a high-pass filter as the predicting means.

According to an eleventh invention, in any one of the first to tenth inventions, the speed command used for the operation of the switching means is a speed command created by the speed command means a predetermined time ago. I did it.
That is, in the eleventh aspect of the invention, since the operation of the servo motor based on the speed command takes longer than the switching of the switching means, the control of the switching means and the speed control of the servo motor are performed by using the speed command a predetermined time before. Match the timing.

According to a twelfth aspect, in any one of the first to eleventh aspects, the speed command further comprising a low-pass filter and used for the operation of the switching means is a speed command after passing through the low-pass filter. It was made to be.
According to a thirteenth invention, in any one of the first to eleventh inventions, further comprising a low-pass filter, wherein the speed command used for the operation of the switching means and the speed control of the servo motor is the low-pass filter. It was made to be a speed command after passing the filter.
That is, in the twelfth or thirteenth invention, since the operation of the servo motor based on the speed command takes longer than the switching of the switching means, the control of the switching means and the servo motor are controlled by using the speed command a predetermined time before. Match the speed control timing. Further, by using a low-pass filter, it is possible to cut noise that causes malfunction of the switching means.

According to a fourteenth aspect, in any one of the first to thirteenth aspects, the pressure command means for commanding a pressure generated between the die cushion and the slide, and the die cushion and the slide Pressure detecting means for detecting a pressure generated between the servo motor and the speed command means based on the pressure command created by the pressure command means and the detected pressure detected by the pressure detection means. Command speed.
That is, in the fourteenth invention, the die cushion can be controlled with higher accuracy by further combining the pressure control between the die cushion and the slider.

According to a fifteenth aspect, in any one of the first to thirteenth aspects, the pressure command means for commanding a pressure generated between the die cushion and the slide, and the die cushion and the slide A pressure detection means for detecting a pressure generated therebetween, a position command means for commanding the position of the die cushion, and a position detection means for detecting the position of the die cushion, and the pressure generated by the pressure command means Of the first speed command created based on the command and the detected pressure detected by the pressure detection means, the position command created by the position command means, and the second speed command detected by the position detection means Using at least one of the above, or using the result of the calculation of the first speed command and the second speed command, the speed command means Degree to command.
That is, in the fifteenth invention, the die cushion can be controlled with higher accuracy by further combining the pressure control between the die cushion and the slider and the position control of the die cushion.

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, for example, a CNC 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. 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 lifting mechanism 50 that lifts and lowers the cushion pad 16. . A plurality of cushion pins 30 extending from the top surface of the cushion pad 16 protrude from the bolster 15 through the holes of the bolster 15. The workpiece 45 is supported at the tip of the cushion pin 30.

  The cushion pad 16 is disposed in association with the second mold 27, and the rod 51 extends from the lower surface of the cushion pad 16. The piston 52 provided at the tip of the rod 51 slides in a die cushion cylinder 60 (hereinafter simply referred to as “cylinder 60”) filled with sealing oil. As illustrated, the cylinder 60 is partitioned into an upper chamber 61 and a lower chamber 62 by a piston 52.

  On the other hand, a hydraulic pump 55 is connected to the output shaft 19 of the servo motor 18. The hydraulic pump 55 is provided in a pipe 63 connected to the switcher 70. As shown in the drawing, both ends of the pipe 63 terminate as connection points 71 and 74 in the switching device 70, respectively. In the present invention, the hydraulic pump 55 is driven only in one direction according to the rotation of the output shaft 19, and the sealing oil in the pipe 63 flows from the connection point 71 side toward the connection point 74 side.

  As shown, the switcher 70 includes other connection points 72, 73, 75, 76. The switcher 70 can switch the connection point 71 of the pipe 63 between the connection point 72 and the connection point 73, and can switch the connection point 74 of the pipe 63 between the connection point 75 and the connection point 76. In the present invention, it is assumed that the switching work of the connection point 71 and the connection point 74 in the switching device 70 is performed at the same time, and these switching work is not performed separately. Such a switching device 70 is, for example, a switching valve, but other switching means may be employed.

  A connection point 72 of the switcher 70 is connected to the upper end 61 of the upper chamber 61 of the cylinder 60 by a pipe 64. Similarly, the connection point 75 of the switching device 70 is connected to the lower end side of the lower chamber 62 of the cylinder 60 by a pipe 65. Further, as shown in the drawing, another pipe 66 extending from the pipe 64 is connected to the connection point 76 of the switch 70, and another pipe 67 extending from the pipe 65 is connected to the connection point 73 of the switch 70. Yes.

  The cylinder 60 and the pipes 63 to 67 are filled with sealing oil. Therefore, when the switch 70 is switched so that the connection point 71 and the connection point 72 are connected and the connection point 74 and the connection point 75 are connected, the hydraulic pump 55 seals the inside of the upper chamber 61. Oil is supplied to the lower chamber 62 through the pipe 64, the pipe 63 and the pipe 65. This raises the piston 52 and the associated die cushion mechanism 20.

  Further, when the switch 70 is switched so that the connection point 71 and the connection point 73 are connected and the connection point 74 and the connection point 76 are connected, the hydraulic oil is sealed in the lower chamber 62 by the hydraulic pump 55. Is supplied to the upper chamber 61 through the pipe 65, the pipe 67, the pipe 63, the pipe 66 and the pipe 64. In this case, the piston 52 and the associated die cushion mechanism 20 are lowered.

  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. When the press machine operates, the control device 10 performs the switching operation described above, so that the slide 24 is lowered. For this reason, the first mold 26 presses the plurality of cushion pins 30 through the workpiece 45. Thereby, the cushion pad 16 is pushed downward.

  On the other hand, the servo motor 18 is rotated by the control device 10 in accordance with the lowering operation of the cushion pad 16, and the hydraulic pump 55 is operated so that the cushion pad 16 is lowered. When the force (pressure) acting on the cushion pad 16 is increased, the cushion pin 30 is further lowered, and the workpiece 45 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 hydraulic pump 55 through the servo motor 18 to generate a relative pressure (ie, force F) between the cushion pad 16 and the slide 24. The servo motor 18 is connected to the servo motor speed detection unit 22, whereby the rotation speed of the servo motor 18 is detected as the detection speed Vd of the servo motor. The servo motor speed detection unit 22 is connected to the control device 10.

  As shown in FIG. 1, a die cushion position detection unit 25 is disposed adjacent to the support unit 12, and the die cushion position detection unit 25 is also connected to the control device 10. The die cushion position detector 25 detects the vertical position of the die cushion 20, particularly the vertical position of the cushion pad 16, and supplies this to the control device 10.

  Furthermore, a pressure detector 53 that detects the pressure in the lower chamber 62 of the cylinder 60 is provided in the pipe 65. It is assumed that the detected pressure detected by the pressure detection unit 53 is also supplied to the control device 10. The servo motor speed detection unit 22 can employ a known encoder, and the die cushion position detection unit 25 can employ a known linear scale.

  FIG. 2A is a functional block diagram showing the control device for the die cushion mechanism according to the first embodiment of the present invention. As shown in FIG. 2A, the control device 10 includes a pressure command unit 81 that creates a pressure command Pc related to the pressure in the lower chamber 62, and a speed command unit 82 that creates a speed command Vc related to the speed of the servo motor 18. And a current command unit 83 that creates a current command Ic related to the current flowing through the servomotor 18.

  As illustrated, a pressure deviation ΔP between the pressure command Pc created by the pressure command unit 81 and the detected pressure Pd detected by the pressure detection unit 53 is supplied to the speed command unit 82. The speed command unit 82 creates a speed command Vc based on the pressure deviation ΔP by a known method. Strictly speaking, the speed command unit 82 creates an absolute value | Vc | of the speed command Vc or a value “− | Vc |” obtained by multiplying the absolute value | Vc | by “−1”. Next, the speed deviation ΔV between the absolute value | Vc | of the speed command Vc (or the negative value “− | Vc |” of the absolute value | Vc |) and the detected speed Vd from the servo motor speed detector 22 is a current. It is supplied to the command unit 83.

  The negative value “− | Vc |” of the absolute value | Vc | is used, for example, when the die cushion is lowered. In the present invention, the absolute value | Vc | or the negative value “− | Vc |” is used because the rotation direction of the servo motor 18 is one direction.

  The current command unit 83 creates a current command Ic by a known method based on the speed deviation ΔV. Next, the current command Ic is supplied to the servo motor 18 via a driver (not shown), and the servo motor 18 is driven according to the current command Ic.

  By the way, in the first embodiment of the present invention, the sign of the speed command Vc of the servo motor 18 created by the speed command unit 82 is constantly supplied to the switcher 70. For example, when the sign of the speed command Vc is plus, the connection point 71 and the connection point 74 of the switcher 70 are connected to the connection point 72 and the connection point 75, respectively, and the die cushion 20 moves up. Similarly, when the sign of the speed command Vc is negative, the connection point 71 and the connection point 74 of the switcher 70 of the switcher 70 are connected to the connection point 73 and the connection point 76, respectively, and the die cushion 20 Descends. In the first embodiment of the present invention, the switcher 70 performs a switching operation when the sign of the speed command Vc changes.

  That is, for example, when the sign of the speed command Vc changes from plus to minus, the switcher 70 switches the connection point 71 from the connection point 72 to the connection point 73 and switches the connection point 74 from the connection point 75 to the connection point 76. Similarly, when the sign of the speed command Vc changes from minus to plus, the switcher 70 switches the connection point 71 from the connection point 73 to the connection point 72 and switches the connection point 74 from the connection point 76 to the connection point 75.

  By such switching operation of the switching device 70, the flow of the sealing oil in each pipe is reversed smoothly and quickly. As a result, the die cushion is switched from the raised state to the lowered state or from the lowered state to the raised state. That is, in this embodiment, since the switcher 70 is operated based on the sign change of the speed command Vc, the switcher 70 can be controlled at high speed and with high accuracy, and as a result, the die cushion can be operated smoothly. Is possible.

  FIG.2 (b) is a functional block diagram which shows the control apparatus of the die cushion mechanism based on other embodiment of this invention. In the embodiment shown in FIG. 2B, the sign of the detected speed Vd of the servomotor 18 detected by the servomotor speed detecting unit 22 is supplied to the switcher 70. In other words, in the present embodiment, the speed command Vc created by the speed command unit 82 is not used, and the sign of the detected speed Vd of the servo motor 18 is used instead. In such a case, since the switching operation is performed based on the change in the sign of the actual speed Vd of the servo motor 18, it will be understood that a more precise operation than that described above is possible.

  FIG. 3 is a first flowchart showing an operation program of the control device for the die cushion mechanism according to the present invention. It is assumed that the operation program 110 shown in FIG. 3 and other operation programs 120, 130, and 140 described later are stored in advance in a storage unit (not shown) of the control device 10. Further, in the operation programs 110 to 140, the sign change of the speed command Vc created in the speed command unit 82 is used as a reference for determination, but the sign change of the detected speed Vd can be used instead. is there.

  In step 111 of the operation program 110 shown in FIG. 3, it is determined whether or not a sign change of the speed command Vc has occurred. If a sign change has occurred, the value of the speed command Vc is set to a predetermined lower limit value in step 112. It is further determined whether or not it is between a and a predetermined upper limit value b. The lower limit value a and the upper limit value b are slightly larger than zero, and are sufficiently small so that no impact is generated on the die cushion 20 when the switcher 70 is switched. In the operation program 110, when the value of the speed command Vc is between the predetermined lower limit value a and the predetermined upper limit value b, the switching operation of the switcher 70 is performed in step 113.

  In this way, when the switching operation is performed when the speed command Vc is in the range between the predetermined lower limit value a and the upper limit value b, it can be said that the speed of the servo motor 18 is sufficiently small. Even if the switching operation is performed, no impact is generated on the die cushion 20. In other words, an impact may occur in the die cushion 20 when switching is performed immediately after the sign is changed, but such an impact can be prevented by the operation program 110 described above.

  If NO is determined in steps 111 and 112, the process proceeds to step 114, and the switching operation of the switch 70 is not performed immediately. In this case, the processing may be repeated until the speed command Vc is between a predetermined lower limit value a and an upper limit value b.

  In the embodiment (not shown), instead of determining whether or not the speed command Vc is between the predetermined lower limit value a and the upper limit value b in step 112, the absolute value | Vc | of the speed command Vc is zero. You may make it determine whether it becomes. In this case, the above-mentioned impact can be completely prevented.

  By the way, when the sign of the speed command Vc changes, the actual speed Vd of the servo motor 18 instantaneously becomes zero when the sign changes, and then becomes the speed Vd after the sign change. That is, since there is a time when the actual speed Vd of the servomotor 18 becomes zero, the time required for the control of the die cushion 20 is increased.

  FIG. 4 is a second flowchart showing an operation program of the control device for the die cushion mechanism according to the present invention for solving such a problem. In step 121 of the operation program 120 shown in FIG. 4, it is determined whether or not the value of the speed command Vc is between a predetermined lower limit value c and a predetermined upper limit value d. Next, when it is determined that the speed command Vc is between the predetermined lower limit value c and the upper limit value d, the routine proceeds to step 122, where it is further determined whether or not the speed command Vc is equal to or greater than zero.

  If the speed command Vc is greater than or equal to zero, the predetermined value x is used as the speed command Vc in step 123. On the other hand, if it is determined that the speed command Vc is smaller than zero, the predetermined value −x is used as the speed command Vc in step 124. The absolute value | x | of the predetermined value x is a value relatively close to zero, and the absolute value | x | is smaller than the absolute value | c | and the absolute value | d |.

  That is, when the speed command Vc becomes close to zero in the operation program 120, the speed command Vc is maintained at the predetermined value x (or -x) so that the servo motor 18 is not stopped. That is, in the operation program 120, it is possible to avoid the actual speed of the servomotor 18 from becoming zero, so that the die cushion 20 can be controlled more quickly. On the other hand, when the speed command Vc deviates from a predetermined range between the lower limit value c and the upper limit value d (see step 125), the value of the speed command Vc is adopted as it is.

  FIG. 5 is a third flowchart showing an operation program of the control device for the die cushion mechanism according to the present invention. In step 131 of the operation program 130 shown in FIG. 5, it is determined whether or not a sign change of the speed command Vc has occurred. If a sign change has occurred, the value of the speed command Vc is set to a predetermined lower limit e in step 132. It is further determined whether or not it is between a predetermined upper limit value f. The lower limit value e and the upper limit value f are relatively close to zero.

  When the speed command Vc is between the predetermined lower limit value e and the upper limit value f, it can be determined that the absolute value | Vc | of the speed command Vc is relatively close to zero. Generally, when the value of the speed command Vc is close to zero, the switcher 70 may malfunction due to the influence of noise. Therefore, in the operation program 130, the switcher 70 is stopped when the value of the speed command Vc is close to zero (step 133).

  Here, stopping the switching device 70 indicates a state in which both the connection point 71 and the connection point 74 of the switching device 70 are not connected to any of the other connection points 72, 73, 75, and 76 (FIG. 1). See). Therefore, in the operation program 130, it can be avoided that the switcher 70 malfunctions due to the influence of noise.

  On the other hand, if it is determined in step 132 that the speed command Vc has deviated from a predetermined range between the lower limit value e and the upper limit value f, the speed command Vc is large enough to ignore the influence of noise. Since it can be determined, in step 134, the switching operation of the switch 70 is performed. If there is no sign change in the speed command Vc in step 131, the switching operation of the switcher 70 is not performed as in step 114 of the operation program 110 (step 135). Note that the detected speed Vd may be used instead of the speed command Vc.

  FIG. 6 is a fourth flowchart showing the operation program of the control device for the die cushion mechanism according to the present invention. In step 141 of the operation program 140 shown in FIG. 6, it is determined whether or not a sign change of the speed command Vc has occurred. If a sign change has occurred, the value of the detected speed Vd is set to a predetermined lower limit value in step 142. It is further determined whether or not it is between g and a predetermined upper limit value h. As in the case described above, the lower limit value g and the upper limit value h are relatively close to zero.

  If the detection speed Vd is between the predetermined lower limit value g and the upper limit value h, the process proceeds to step 144, and the absolute value | Vc | or its negative value “− | Vc |” is used as usual. The speed deviation ΔV is created. On the other hand, if the detected speed Vd deviates from the range between the lower limit value g and the upper limit value h, the process proceeds to step 143, and the speed deviation ΔV is created using the speed command Vc after the sign change. .

  The reason for performing such control is as follows. When the sign of the speed command Vc changes, the actual detected speed Vd of the servo motor 18 once becomes zero, and then the servo motor 18 again in the same direction based on the speed command Vc after the switching operation of the switch 70. Rotate. For this reason, after the change of the sign of the speed command Vc, it is desired that the actual speed Vd of the servo motor 18 is made zero by a relatively large torque, thereby shortening the required time. In order to obtain a relatively large torque, it is necessary to increase the speed deviation ΔV.

  In general, the speed deviation ΔV represented by “Vc−Vd” is larger than the speed deviation ΔV represented by “| Vc | −Vd” or “− | Vc | −Vd”. Therefore, in the embodiment shown in FIG. 6, when the detected speed Vd deviates from the range between the lower limit value g and the upper limit value h, that is, when the detected speed Vd is relatively large, the speed after the sign change. The command Vc is used as it is.

  Thereby, after the sign change of the speed command Vc, the detected speed Vd of the servo motor 18 can be quickly made zero. That is, by such control, the die cushion 20 can be controlled more quickly. As can be seen from FIG. 6, when there is no sign change of the speed command Vc in step 141, the switching operation of the switch 70 is not performed as in step 114 of the operation program 110. In the embodiment described with reference to FIGS. 3 to 6, the upper limit values a, c, e, and g may be equal to each other, and the lower limit values b, d, f, and h may be equal to each other. .

  FIG. 7A to FIG. 7C are functional block diagrams showing a control device for the die cushion mechanism according to the second embodiment of the present invention. In the embodiment shown in FIGS. 7A to 7C, the prediction unit 86 is provided immediately after the speed command unit 82. The prediction unit 86 in the present embodiment serves to predict the value of the speed command Vc ′ after a predetermined time from the current time.

  FIG. 8 is a diagram showing an example of the prediction method of the prediction unit, where the vertical axis indicates the speed command Vc and the horizontal axis indicates time. The speed command Vc is created at predetermined intervals. In FIG. 8, the speed command Vc at the current time nT is represented as a speed command Vc (n).

  The prediction unit 86 obtains the speed command Vc (n + 1) at a time (n + 1) T that is a predetermined time after the current time nT as follows. First, the rate of change a (n) of the speed command Vc is calculated from the speed command Vc (n-1) at the time (n-1) T before the predetermined time and the speed command Vc (n) at the current time nT. Next, the rate of change a (n + 1) between the speed command Vc (n) at the current time nT and the speed command Vc (n + 1) at time (n + 1) T after a predetermined time becomes the rate of change a (n) described above. Assume that they are equal. Next, a speed command Vc (n + 1) at a time (n + 1) T after a predetermined time is calculated based on the assumption described above.

  In the embodiment shown in FIG. 7A, the sign of the speed command Vc ′ predicted by the prediction unit 86 is supplied to the switch 70 as described above. That is, in the embodiment shown in FIG. 7A, the predicted future speed command is used, so that the die cushion mechanism can be controlled more quickly.

  Note that, as shown in FIG. 7D, the prediction unit 86 may be employed even when the sign of the detection speed Vd detected by the servo motor speed detection unit 22 is supplied to the switch 70. That is, in the embodiment shown in FIG. 7D, the prediction unit 86 calculates the detection speed Vd ′ after a predetermined time from the change rate of the detection speed Vd, and supplies the sign to the switch 70. Again, it will be appreciated that the die cushion can be controlled more quickly in the same manner as described above.

Further, in the embodiment shown in FIGS. 7B and 7C, the absolute value | Vc of the speed command Vc ′ after a predetermined time when calculating the speed deviation ΔV input to the current command unit 83. '| Or its negative value “− | Vc ′ |” may be used. In this case, it will be understood that the servo motor 18 can be quickly controlled since the future speed command is used.
By the way, although the switching action of the switching device 70 can be instantaneously performed by a signal from the control device 10, the response of the servo motor 18 may be delayed from the response of the switching device 70 due to inertia and load. In the embodiment shown in FIG. 7C, since only the speed command used for the speed control of the servo motor 18 is passed through the prediction unit 86, the response of the servo motor 18 becomes quicker. As a result, the response timing of the switching device 70 and the response timing of the servo motor 18 can be substantially matched. In other words, the prediction unit 86 is set so that the response of the servo motor 18 and the response of the switcher 70 can be matched.

  In the embodiment shown in FIGS. 7 (a) to 7 (d), a prediction for calculating the future speed command Vc ′ or the detected speed Vd ′ using the rate of change of the speed command Vc or the detected speed Vd. Portion 86 is shown. In the embodiment (not shown), a high-pass filter (not shown) may be provided instead of the prediction unit 86, and the speed command Vc ′ or the detected speed Vd ′ obtained through the high-pass filter is used. It may be used as a value after a predetermined time.

  FIG. 9A and FIG. 9B are functional block diagrams showing a control device for a die cushion mechanism based on the third embodiment of the present invention. In the embodiment shown in FIGS. 9A and 9B, the speed command Vc created by the speed command unit 82 is passed through the low-pass filter 87. As a result, an accurate speed command Vc ′ from which high-frequency noise has been cut is created. In the third embodiment, since the accurate sign of the speed command Vc 'is supplied to the switcher 70, more accurate control is possible.

  In the embodiment shown in FIG. 9B, since the low-pass filter 87 is passed, the response of the switcher 70 is delayed. As a result, the response timing of the switching device 70 and the response timing of the servo motor 18 can be substantially matched. In other words, the low-pass filter 87 is set so that the response of the servo motor 18 and the response of the switcher 70 can be matched.

  Note that, as shown in FIG. 9C, the low pass filter 87 may be employed even when the sign of the detected speed Vd detected by the servo motor speed detecting unit 22 is supplied to the switch 70. In this case as well, it will be understood that the response timing of the switcher 70 and the response timing of the servo motor 18 can be made to be substantially the same as in the case of FIG. 9B.

  FIG. 10 is a functional block diagram showing a control device for a die cushion mechanism according to the fourth embodiment of the present invention. In the embodiment shown in FIG. 10, the speed command Vc created by the speed command unit 82 is passed through the delay element 88.

  The delay element 88 shown in FIG. 10 is a kind of storage device, which sequentially stores the speed command Vc input at a predetermined cycle and sequentially outputs the speed command Vc input at a predetermined time. Yes. That is, when the speed command Vc input to the delay element 88 from the speed command unit 82 is referred to as Vc (n), the delay element 88 outputs the speed command Vc (n−1) input last time, for example, the previous time. .

  Therefore, in the present embodiment, the sign of the speed command Vc ′ a predetermined time before is supplied to the switcher 70. Even in such a case, since the response of the switching device 70 is delayed, the same effect as described above that the response timing of the switching device 70 and the response timing of the servo motor 18 can be substantially matched is obtained.

  FIG. 11 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 embodiment shown in FIG. 11, the control device 10 includes a position command unit 84 that creates a position command Xc related to the position of the die cushion 20, particularly the position of the cushion pad 16, and a die that detects the detection position Xd of the die cushion. And a cushion position detector 25.

  As can be seen from FIG. 11, the second speed command unit 82B included in the control device 10 uses a known method based on the position deviation ΔX between the position command Xc and the detected position Xd of the die cushion, and uses the second speed command VcB. Create Further, in the fifth embodiment of the present invention shown in FIG. 11, the speed command unit 82 is shown as a first speed command unit 82A that outputs a first speed command VcA.

The control device 10 also includes a computing unit 85 that creates a speed command Vc from the first speed command VcA created by the first speed command unit 82A and the second speed command VcB created by the second speed command unit 82B. The computing unit 85 creates a speed command Vc based on the following equation (1).
Vc = (1−α) · VcB + α · VcA (1)

  The variable α in the equation (1) varies depending on the magnitude of the detected pressure Pd. FIG. 12 is a diagram showing the relationship between the variable α and the detected pressure Pd. As shown in FIG. 12, the variable α is zero when the detected pressure Pd is equal to or lower than the predetermined value P1, and is 1 when the detected pressure Pd is equal to or higher than another predetermined value P2 greater than the predetermined value P1. . Furthermore, the variable α changes linearly as shown when the detected pressure Pd is between the predetermined values P1 and P2.

  In the embodiment shown in FIG. 11, a first speed command VcA is created in the first speed command section 82A by pressure control between the die cushion and the slider, and in the second speed command section 82B by position control of the die cushion. A second speed command VcB is created. Then, the calculation unit 85 creates a speed command Vc from the first speed command VcA and the second speed command VcB, and the sign thereof is supplied to the switcher 70. That is, in the embodiment shown in FIG. 11, it is possible to control the die cushion with higher accuracy by combining the pressure control between the die cushion and the slider and the position control of the die cushion.

  As a matter of course, the scope of the present invention also applies to the case where the arithmetic unit 85 is excluded and either one of the first speed command VcA and the second speed command VcB is supplied to the switch 70. included. Furthermore, some of the above-described embodiments may be appropriately combined.

It is a schematic diagram which shows the basic composition of the die cushion mechanism based on this invention. (A) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 1st embodiment of this invention. (B) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on other embodiment of this invention. It is a 1st flowchart which shows the operation | movement program of the control apparatus of the die cushion mechanism based on this invention. It is a 2nd flowchart which shows the operation | movement program of the control apparatus of the die cushion mechanism based on this invention. It is a 3rd flowchart which shows the operation | movement program of the control apparatus of the die cushion mechanism based on this invention. It is a 4th flowchart which shows the operation | movement program of the control apparatus of the die cushion mechanism based on this invention. (A) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 2nd embodiment of this invention. (B) It is another functional block diagram which shows the control apparatus of the die cushion mechanism based on 2nd embodiment of this invention. (C) It is another functional block diagram which shows the control apparatus of the die cushion mechanism based on 2nd embodiment of this invention. (D) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on other embodiment of this invention. It is a figure which shows one example of the prediction method of a prediction part. (A) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 3rd embodiment of this invention. (B) It is another functional block diagram which shows the control apparatus of the die cushion mechanism based on 3rd embodiment of this invention. (C) It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on other embodiment of this invention. It is a functional block diagram which shows the control apparatus of the die cushion mechanism based on 4th embodiment of this invention. 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 figure which shows the relationship between the variable (alpha) and detected pressure Pd.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control apparatus 11 Base 12 Support part 13 Damper 15 Bolster 16 Cushion pad 18 Servo motor 19 Output shaft 20 Die cushion 22 Servo motor speed detection part 24 Slide 25 Die cushion position detection part 26 First type 27 Second type 30 Cushion pin 45 Workpiece 50 Lifting mechanism 51 Rod 52 Piston 53 Pressure detector 55 Hydraulic pump 60 Die cushion cylinder 61 Upper chamber 62 Lower chamber 63-67 Piping 70 Switch 71-76 Connection point 81 Pressure command section 82 Speed command section 82A 1st Speed command unit 82B Second speed command unit 83 Current command unit 84 Position command unit 85 Calculation unit 86 Prediction unit 87 Low pass filter 88 Delay element Ic Current command Pc Pressure command Pd Detection pressure Vc Speed command Vc 'Filter, predictor, delay element The Spent speed command VcA first velocity command VcB second speed command Vd detected speed Vd 'filter, detection speed Xc position command Xd detected position ΔP pressure deviation ΔV speed deviation ΔX positional deviation that has passed through the predictor

Claims (15)

A control device for a die cushion mechanism that generates a force against a slide of a press machine using a servo motor as a drive source,
Speed command means for commanding the speed of the servo motor;
Speed detecting means for detecting the speed of the servo motor;
Switching means for switching the rising and lowering of the die cushion,
The switching means operates based on a change in the sign of the speed command of the servo motor created by the speed command means or a change in the sign of the detection speed of the servo motor detected by the speed detection means. Control device for the mechanism.   The switching means is not operated until the detected speed detected by the speed detecting means is zero or smaller than a predetermined value even when the speed command or the sign of the detected speed is changed. The control apparatus of the die cushion mechanism of 1.   The speed command is maintained at a predetermined value different from zero when the speed command is within a predetermined range when the speed command or the sign of the detected speed changes. The control apparatus of the die cushion mechanism as described.   If the speed command is zero or is within a predetermined range when the speed command or the sign of the detected speed changes, the switching means is controlled so that the die cushion does not rise and fall. The control device for a die cushion mechanism according to claim 1.   2. The switching unit according to claim 1, wherein when the speed command or the sign of the detected speed changes, the switching unit is controlled so that the die cushion does not rise and fall until the detected speed falls within a predetermined range. Control device for die cushion mechanism.   The die cushion according to claim 1, wherein when the speed command or the sign of the detected speed is changed, the speed command of the sign after the change is used until the detected speed is within a predetermined range. Control device for the mechanism. And further comprising prediction means for predicting a future speed command created by the speed command means,
The sign of the speed command predicted by the predicting means is used as the sign of the speed command created by the speed command means, thereby operating the switching means. The control device for a die cushion mechanism according to one item. And further comprising prediction means for predicting a future speed command created by the speed command means,
7. The speed command predicted by the prediction means is used simultaneously as a speed command used for speed control of a servo motor and a sign of the speed command created by the speed command means. The control apparatus of the die cushion mechanism as described. And further comprising prediction means for predicting a future speed command created by the speed command means,
7. The speed command predicted by the prediction means is used only as a speed command for a servo motor, and the switching means is operated with a sign of a speed command before prediction. Die cushion mechanism control device. And further comprising prediction means for predicting a future detection speed detected by the speed detection means,
The sign of the detection speed predicted by the prediction means is used as the sign of the detection speed detected by the speed detection means, and thereby the switching means is operated. The control device for a die cushion mechanism according to one item.   The die cushion mechanism according to any one of claims 1 to 10, wherein the speed command used for the operation of the switching means is a speed command created by the speed command means a predetermined time ago. Control device. Furthermore, it has a low-pass filter,
The control device for a die cushion mechanism according to any one of claims 1 to 11, wherein the speed command used for the operation of the switching means is a speed command after passing through the low-pass filter. Furthermore, it has a low-pass filter,
The die cushion mechanism according to any one of claims 1 to 11, wherein the speed command used for the operation of the switching means and the speed control of the servo motor is a speed command after passing through the low-pass filter. Control device. A pressure command means for commanding a pressure generated between the die cushion and the slide;
Pressure detecting means for detecting pressure generated between the die cushion and the slide;
The speed command means commands the speed of the servo motor based on a pressure command created by the pressure command means and a detected pressure detected by the pressure detection means. The control apparatus of the die cushion mechanism as described in 2. A pressure command means for commanding a pressure generated between the die cushion and the slide;
Pressure detecting means for detecting pressure generated between the die cushion and the slide;
Position command means for commanding the position of the die cushion;
Comprising position detecting means for detecting the position of the die cushion,
Detected by the first speed command created based on the pressure command created by the pressure command means and the detected pressure detected by the pressure detection means, the position command created by the position command means, and the position detection means The speed command means commands the speed of the servo motor using at least one of the second speed commands generated or using a calculation result of the first speed command and the second speed command. The control apparatus of the die cushion mechanism as described in any one of 1 to 13.

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