JP2011152569A - Device and method for controlling hydraulic die cushion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for controlling a hydraulic die cushion device, by which a target cushion force is immediately generated while suppressing overshooting. <P>SOLUTION: The controlling device 30 controls the action of the hydraulic die cushion device 20 which includes a die cushion pad 22 which touches a slide 10 and is uniaxially movable linked with the movement of the slide 10 and a hydraulic cylinder 23 for driving the die cushion pad 22. A second cushion force which is larger than a first cushion force to be generated in the hydraulic cylinder 23 on and after a point of time (point of time of contact) when the slide 10 touches the die cushion pad 22 is generated preliminarily by the hydraulic cylinder 23 before the point of time of contact, the control for bringing into a state where the cushion force of the hydraulic cylinder 23 is reduced at the point of time of contact is performed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device and a control method for a hydraulic die cushion device.

  The hydraulic die cushion device is provided in a press machine that molds the work piece between the upper mold and the lower mold. Is a device that generates a reaction force and a push-up force (pressing force against a slide that is a movable part of a press machine: cushion force) for press-molding a workpiece. The hydraulic die cushion device includes a die cushion pad to which a lower mold is attached, a hydraulic cylinder that drives the die cushion pad, and a control device that controls the hydraulic cylinder to generate the cushion force.

  FIG. 4 is a diagram showing ideal characteristics of the hydraulic die cushion device. Ideally, the hydraulic die cushion device can achieve high-speed response without occurrence of overshoot. That is, as shown in FIG. 4, at the time t1 when the slide collides (contacts) with the die cushion pad of the hydraulic die cushion device, the target cushion force F1 can be generated immediately without generating an extra cushion force. Ideal.

  Conventionally, a preload method has been proposed as one of methods for realizing high-speed response. FIG. 5 is a diagram for explaining a conventional preloading method. As shown in FIG. 5, the preload method is a method in which a target cushioning force F1 is generated in advance and waits for a slide collision before time t1 when the slide collides with the die cushion pad. In this method, since the target cushioning force F1 is already obtained at time t1 when the slide collides with the hydraulic die cushion device, high-speed response is realized compared to the case where the cushioning force is generated only at time t1. Is possible.

  Patent Document 1 below discloses a technique for performing control such that the speed of the die cushion pad does not greatly deviate from the speed of the slide, and preventing the clamping force between the two from being reduced. Specifically, the speed command value of the die cushion is obtained based on the command of the force to be generated between the slide and the die cushion pad and the detection result of the force generated between the two, and the absolute value of this speed command value is A command value for the die cushion is created so as not to exceed a threshold value equal to or greater than the absolute value of the detected slide speed.

Japanese Patent No. 4189419

  By the way, in the preload method described above, the servo valve starts to move at a predetermined timing (timing in consideration of the dead time Ta and response time Tb of the servo valve of the hydraulic cylinder) before the timing at which the slide collides. It is necessary to perform control so that the timing at which the cushion force is adjusted and the timing at which the slide collides exactly. For this reason, there is a problem that excessive overshoot occurs when the timing of control switching is shifted. Further, depending on the mechanism of the hydraulic die cushion device, there is a problem in that overshoot may occur due to vibration caused by a shift in timing for adjusting the cushion force.

  FIG. 6 is a diagram showing an example of overshoot that occurs when the conventional preload method is used. In FIG. 6, a curve denoted by reference numeral C100 is a curve indicating a command value for driving a hydraulic cylinder provided in the hydraulic die cushion device, and a curve denoted by reference numeral F100 is a curve indicating a cushion force generated in the hydraulic cylinder. As shown in FIG. 6, when the timing for adjusting the cushion force deviates from the timing at which the slide collides (time t1), the cushion force generated in the hydraulic cylinder overshoots, and a command to drive the hydraulic cylinder to suppress this overshoot. The value also vibrates.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device and a control method for a hydraulic die cushion device that can immediately generate a target cushion force while suppressing overshoot. To do.

In order to solve the above-described problem, a control device for a hydraulic die cushion device according to the present invention comprises a contact member (22) that contacts a contact object (10) and is uniaxially movable in conjunction with the movement of the contact object; A control device (30, 50) of a hydraulic die cushion device (20, 40) comprising a hydraulic cylinder (23, 41) for driving the contact member, wherein the contact object comes into contact with the contact member. A second cushion force larger than the first cushion force to be generated in the hydraulic cylinder after the contact point is generated in the hydraulic cylinder in advance before the contact point, and the cushion force of the hydraulic cylinder is reduced at the contact point. It is characterized in that it is controlled to be in a state where
In the control device for the hydraulic die cushion device according to the present invention, the cushion force of the hydraulic cylinder at the time of contact may be reduced between the first cushion force and the second cushion force. It is characterized by control.
In the control device for the hydraulic die cushion device according to the present invention, the hydraulic die cushion device includes a valve device (24) that supplies and discharges oil to and from the hydraulic cylinder, and controls the valve device. The cushion force generated in the hydraulic cylinder is controlled.
In the control device for the hydraulic die cushion device of the present invention, the hydraulic die cushion device includes a motor (43) that moves a drive mechanism that pressurizes and depressurizes the oil in the hydraulic cylinder. Controlling the cushioning force generated in the hydraulic cylinder is performed.
The control method of the hydraulic die cushion device of the present invention includes a contact member (22) that contacts the contact object (10) and can move in one axis in conjunction with the movement of the contact object, and a hydraulic cylinder that drives the contact member (23, 41) and a control method of the hydraulic die cushion device (20, 40), wherein the hydraulic cylinder is to be generated after a contact time point, which is a time point when the contact object contacts the contact member. A first step of causing the hydraulic cylinder to generate a second cushion force that is greater than one cushion force in advance before the contact time point and a state in which the cushion force of the hydraulic cylinder is reduced at the contact time point are controlled. And a second step.
In the control method of the hydraulic die cushion device according to the present invention, the second step includes reducing the cushion force of the hydraulic cylinder at the contact time point between the first cushion force and the second cushion force. It is the step which controls to be in the state which exists.

  According to the present invention, a second cushion force that is greater than the first cushion force to be generated in the hydraulic cylinder after the contact time point when the contact object contacts the contact member is previously applied to the hydraulic cylinder before the contact time point. Since the control is performed so that the cushioning force of the hydraulic cylinder is reduced at the time of contact, the target cushioning force can be generated immediately while suppressing overshooting at the time of contact. is there.

It is a side view which shows schematic structure of a press provided with a hydraulic die cushion apparatus. It is a figure for demonstrating operation | movement of the control apparatus by one Embodiment of this invention. It is a figure which shows the modification of a press machine. It is a figure which shows the ideal characteristic of a hydraulic die cushion apparatus. It is a figure for demonstrating the conventional preload method. It is a figure which shows an example of the overshoot which arises when the conventional preload method is used.

  Hereinafter, a control device and a control method of a hydraulic die cushion device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view showing a schematic configuration of a press machine including a hydraulic die cushion device. As shown in FIG. 1, the press machine 1 includes a slide 10 (contact object) and a hydraulic die cushion device 20. The slide 10 collides (contacts) with the hydraulic die cushion device 20. The sandwiched panel P (workpiece) is press-molded.

  The slide 10 is configured to be capable of reciprocating in the vertical direction, and an upper mold D1 for press-molding the panel P is attached to the lower part thereof. Specifically, the slide 10 is reciprocated by a crank mechanism that includes a crankshaft 11 that is rotationally driven by a main motor (not shown), and a connecting rod 12 that connects an eccentric portion of the crankshaft 11 and an upper portion of the slide 10. Is possible.

  The crank mechanism is provided with a rotation angle sensor 13 for detecting the rotation angle of the crankshaft 11, and the speed of the slide 10 and the time point at which the slide 10 collides are obtained by the rotation angle detected by the rotation angle sensor 13. It is done. The detection result of the rotation angle sensor 13 is output to a control device (not shown) that controls the operation of the slide 10 and a control device 30 that controls the operation of the hydraulic die cushion device 20.

  The hydraulic die cushion device 20 includes a cushion pin 21, a die cushion pad 22, a hydraulic cylinder 23, a servo valve 24 (valve device), a logic valve 25, a check valve 26, a stroke sensor 27, and pressure sensors 28a and 28b. Under the control of the control device 30, a reaction force for wrinkle pressing and a cushioning force for press-molding the panel P are generated. The die cushion pad 22 is disposed below the slide 10 and supports the lower mold D <b> 2 via the cushion pin 21.

  The die cushion pad 22 is connected to the lower end of one end of the piston of the hydraulic cylinder 23 and can move vertically downward in conjunction with the movement of the slide 10 when the slide 10 collides. The hydraulic cylinder 23 includes an upper chamber 23a and a lower chamber 23b that are partitioned at the other end of the piston, and a necessary cushioning force is obtained by supplying and discharging oil to and from the upper chamber 23a and the lower chamber 23b. appear. The servo valve 24 switches the supply destination (the upper chamber 23a or the lower chamber 23b of the hydraulic cylinder 23) and the supply amount of pressurized oil supplied from a pump (not shown) under the control of the control device 30, and The oil discharge source (the upper chamber 23a or the lower chamber 23b of the hydraulic cylinder 23) and the discharge amount are switched. The oil discharged from the hydraulic cylinder 23 is stored in a tank (not shown) that stores oil used in the hydraulic cylinder 23.

  The logic valve 25 is provided in a pipe connecting the upper chamber 23 a of the hydraulic cylinder 23 and the servo valve 24, and the flow path of this pipe is turned off or opened under the control of the control device 30. The check valve 26 is provided in a pipe connecting the upper chamber 23a of the hydraulic cylinder 23 and the servo valve 24 and a tank (not shown), and the hydraulic pressure of the upper chamber 23a of the hydraulic cylinder 23 is preset. It is a valve that opens when it becomes smaller than the threshold value.

  The stroke sensor 27 is a sensor that detects the amount of movement of the die cushion pad 22 in the vertical direction. The pressure sensors 28a and 28b are sensors that detect the hydraulic pressure in the upper chamber 23a and the hydraulic pressure in the lower chamber 23b, respectively. Although not shown in FIG. 1, the detection results of the stroke sensor 27 and the pressure sensors 28 a and 28 b are output to the control device 30.

  The control device 30 adjusts the cushion force generated in the hydraulic cylinder 23 by controlling the servo valve 24 and the logic valve 25 using the detection results of the rotation angle sensor 13, the stroke sensor 27, and the pressure sensors 28a and 28b. Thus, the operation of the hydraulic die cushion device 20 is controlled. Here, when press-molding the panel P, the control device 30 generates an excessive cushion force in the hydraulic cylinder 23 in advance (over preload), and the cushion force of the hydraulic cylinder 23 is reduced when the slide 10 collides. Control to make it in a state that is

  Specifically, when the time point at which the slide 10 collides with the die cushion pad 22 is time t1, the control device 30 causes the cushion force F1 (target value: first cushion force) to be generated in the hydraulic cylinder 23 after time t1. Control is performed to cause the hydraulic cylinder 23 to generate a larger cushion force F2 (second cushion force) before time t1. Then, at a predetermined timing before time t1, the servo valve 24 is opened and the cushioning force is gradually reduced. At time t1, the cushioning force of the hydraulic cylinder 23 is between the cushioning force F1 and the cushioning force F2. Control the cushion force. This control is performed in order to immediately generate a target cushion force while suppressing overshoot during a collision.

  Here, if the magnitude of the cushioning force F2 is larger than the cushioning force F1, it can be set to an arbitrary magnitude. However, if the cushioning force F2 is too large, it takes time to reduce the cushioning force. End up. For this reason, it is desirable that the magnitude of the cushioning force F2 is set so that the time required for reducing the cushioning force of the hydraulic cylinder 23 from the cushioning force F2 to the cushioning force F1 is within a few seconds.

  Next, operation | movement of the press machine in the said structure is demonstrated. FIG. 2 is a diagram for explaining the operation of the control device according to the embodiment of the present invention. In FIG. 2, a curve denoted by reference numeral C10 is a curve indicating a command value (command value indicating the opening degree of the servo valve 24) output from the control device 30 to the servo valve 24, and denoted by reference numeral F10. A curve is a curve which shows the cushioning force which arises with a hydraulic cylinder.

  The slide 10 provided in the press machine 1 and the die cushion pad 22 of the hydraulic die cushion device 20 are respectively arranged at a predetermined height position by the control of the control device 30 or the like before starting the molding of the panel P. . In addition, the height position where the slide 10 is disposed is H1, and the height position where the die cushion pad 22 is disposed is H2. And the panel P is arrange | positioned on the lower metal mold | die D2 supported on the die cushion pad 20 via the cushion pin 21. FIG.

  When the above arrangement is completed, the control device 30 controls the servo valve 24 to generate a cushion force F2 larger than the cushion force F1 to be generated in the hydraulic cylinder 23 after the collision of the slide 10, as shown in FIG. Over preload: first step). When the hydraulic cylinder 23 is in an over-preloaded state, the torque of the main motor is controlled by control of a control device (not shown) to start the rotation of the crankshaft 11, thereby starting the lowering of the height slide 10.

  When the slide 10 starts to descend, the control device 30 opens the servo valve 24 to gradually decrease the cushion force, and when the slide 10 collides, the cushion force of the hydraulic cylinder 23 becomes the above-described cushion force F1. Control is performed so that the cushioning force is between the cushioning force F2 (second step). By such control, the slide 10 collides with the die cushion pad 22 in a state where the cushioning force of the hydraulic cylinder 23 is reduced (time t1).

  Here, in order to simplify the explanation, an example is given in which the cushion force of the hydraulic cylinder 23 is gradually reduced after the slide 10 is lowered. However, for example, if the time required to reduce the cushioning force of the hydraulic cylinder 23 from the cushioning force F1 to the cushioning force F2 is longer than the time required from the start of the lowering of the slide 10 to the collision, the slide 10 is lowered. Before, control for gradually decreasing the cushioning force of the hydraulic cylinder 23 is started.

  After the slide 10 collides with the die cushion pad 22 (after time t1), as shown in FIG. 2, control is performed to generate a cushion force F1 as a target value in the hydraulic cylinder 23. As a result, the slide 10 and the die cushion pad 22 are integrated vertically by a predetermined distance (stroke) while the panel P is sandwiched between the upper mold D1 and the lower mold D2 with the cushioning force F1. Move in the direction. When the movement of the slide 10 and the die cushion pad 22 is completed, the slide 10 is separated from the die cushion pad 22, thereby obtaining a molded product in which the panel P is press-molded in accordance with the upper mold D 1 and the lower mold D 2.

  As described above, in the present embodiment, a cushion force F2 larger than the cushion force F1 to be generated in the hydraulic cylinder 23 after the time t1 when the slide 10 collides with the die cushion pad 22 is preliminarily set before the time t1. 23, and the cushioning force of the hydraulic cylinder 23 is reduced at time t1 (specifically, it is reduced between the cushioning force F1 and the cushioning force F2). Thereby, the robustness with respect to the shift | offset | difference of control switching timing increases, and the target cushion force can be generated immediately, suppressing an overshoot at the time of a collision.

  The control device and the control method for the hydraulic die cushion device according to the embodiment of the present invention have been described above. However, the present invention is not limited to the above embodiment, and can be freely changed within the scope of the present invention. For example, in the above embodiment, the hydraulic die cushion device 20 includes the hydraulic cylinder 23 to which oil is supplied from the outside, and the cushion force generated in the hydraulic cylinder 23 when the control device 30 controls the servo valve 24. An example of controlling the above has been described.

  However, the present invention can also be applied to control of a hydraulic die cushion device including a hydraulic cylinder other than the hydraulic cylinder 23 described above. FIG. 3 is a view showing a modification of the press machine. The press machine 2 shown in FIG. 3 includes a slide 10 and a hydraulic die cushion device 40. The slide 10 collides (contacts) with the hydraulic die cushion device 40, and a panel P (covered) sandwiched therebetween. (Workpiece) is press-molded.

  The die cushion device 40 is provided with a hydraulic cylinder 41 whose cushioning force is controlled by a motor drive, instead of the hydraulic cylinder 23, the servo valve 24, the logic valve 25, and the check valve 26 in the die cushion device 20 shown in FIG. It is a configuration. The hydraulic cylinder 41 includes two pistons P1 and P2. One end of the piston P1 is connected to the lower portion of the die cushion pad 22, and the other end divides the interior of the hydraulic cylinder 41 into an upper chamber 41a and a lower chamber 41b. The piston P2 has one end connected to the movable plate 42 and the other end dividing the lower chamber 41b of the hydraulic cylinder 41 into two. Both the upper chamber 41a and the lower chamber 41b partitioned by the piston P1 are filled with oil.

  The movable plate 42 is a flat member in which holes having screw grooves are formed at both ends. Each hole formed in the movable plate 42 is provided with a cylindrical feed member 44 having a thread formed on the side surface and configured to be rotatable around a shaft by a motor 43. Each axis of the feed member 44 is set in the vertical direction, and when the feed member 44 is rotated at the same speed by the motor 43, the movable plate 42 can be translated in the vertical direction.

  Here, since the movable plate 42 is connected to one end of the piston P2, when the movable plate 42 moves in the vertical direction, the piston P2 moves integrally with the movable plate 42 in the vertical direction. When the movable plate 42 is moved upward by driving the motor 43, the oil sandwiched between the pistons P1 and P2 is pressurized, so that the cushioning force of the hydraulic cylinder 41 can be increased. On the other hand, when the movable plate 42 is moved downward by driving the motor 43, the oil sandwiched between the pistons P1 and P2 is depressurized, so that the cushioning force of the hydraulic cylinder 41 can be reduced. it can.

  The control device 50 controls the motor 43 using the detection results of the rotation angle sensor 13, the stroke sensor 27, and the pressure sensors 28 a and 28 b to adjust the cushion force generated in the hydraulic cylinder 41, thereby providing a hydraulic die cushion. The operation of the device 40 is controlled. Here, similarly to the control device 30 described above, when the panel P is press-molded, the control device 50 causes the hydraulic cylinder 41 to generate an excessive cushion force in advance (over preload), and the slide 10 collides. Control is performed so that the cushioning force of the hydraulic cylinder 41 is sometimes reduced. Therefore, also in the die cushion device 40 having the configuration shown in FIG. 3, it is possible to immediately generate a target cushion force while suppressing overshoot at the time of collision.

10 Slide 20 Hydraulic Die Cushion Device 22 Die Cushion Pad 23 Hydraulic Cylinder 24 Servo Valve 30 Control Device 40 Hydraulic Die Cushion Device 41 Hydraulic Cylinder 43 Motor 50 Control Device

Claims (6)

A control device for a hydraulic die cushion device, comprising: a contact member that contacts a contact object and is movable in one axis in conjunction with the movement of the contact object; and a hydraulic cylinder that drives the contact member,
A second cushion force larger than the first cushion force to be generated in the hydraulic cylinder after the contact time point when the contact object contacts the contact member is generated in the hydraulic cylinder in advance before the contact time point. And controlling the hydraulic cylinder cushion so that the cushioning force of the hydraulic cylinder is reduced at the time of contact.   2. The hydraulic die according to claim 1, wherein a control is performed so that a cushioning force of the hydraulic cylinder at the time of the contact is reduced between the first cushioning force and the second cushioning force. Control device for cushion device. The hydraulic die cushion device includes a valve device for supplying and discharging oil to and from the hydraulic cylinder,
The control device for the hydraulic die cushion device according to claim 1 or 2, wherein a cushion force generated in the hydraulic cylinder is controlled by controlling the valve device. The hydraulic die cushion device includes a motor that moves a drive mechanism that pressurizes and depressurizes the oil in the hydraulic cylinder,
The control device for a hydraulic die cushion device according to claim 1 or 2, wherein a cushion force generated in the hydraulic cylinder is controlled by controlling the motor. A control method for a hydraulic die cushion device, comprising: a contact member that contacts a contact object and is uniaxially movable in conjunction with the movement of the contact object; and a hydraulic cylinder that drives the contact member,
A second cushion force larger than the first cushion force to be generated in the hydraulic cylinder after the contact time point, which is a time point when the contact object contacts the contact member, is applied to the hydraulic cylinder in advance before the contact time point. A first step of generating,
And a second step of controlling the hydraulic cylinder so that the cushioning force of the hydraulic cylinder is reduced at the time of the contact.   The second step is a step of controlling so that a cushioning force of the hydraulic cylinder at the time of contact is reduced between the first cushioning force and the second cushioning force. A control method for a hydraulic die cushion device according to claim 5.

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