JP4838047B2 - Die cushion control device and die cushion control method for press machine - Google Patents

Description

  The present invention relates to a die cushion control device for a press machine used for drawing or the like, and relates to a die cushion control device and a die cushion control method for controlling the operation of a die cushion pad in synchronization with the operation of a slide.

  2. Description of the Related Art Conventionally, as a die cushion control device that controls the lifting / lowering operation of a die cushion pad driven by a servomotor, for example, a device proposed in Patent Document 1 is known. In the die cushion control device according to Patent Document 1, the cushion stroke of the die cushion is controlled by position control until the upper mold of the slide comes into contact with the workpiece. When a change in the current of the servo motor when a load is applied to the die cushion pad is detected, the position control is switched to the pressure control based on the detection signal of the current change, and a preset cushion pressure is applied to the die cushion pad. In such a die cushion control device, since the position control can be switched to the pressure control, the drawing process can be performed satisfactorily.

  By the way, when the upper die of the slide that has been lowered comes into contact with the work on the die cushion that has been stopped in a standby state, a large impact is generated at the time of contact and the machining accuracy is lowered. Therefore, preliminary acceleration is performed on the die cushion, and the upper die of the slide is brought into contact with the workpiece on the die cushion that is descending at a predetermined speed. By performing such preliminary acceleration, the impact at the time of contact between the workpiece and the upper die is mitigated, so that the machining accuracy is improved.

Japanese Patent Laid-Open No. 10-202327

  However, in position control of the die cushion, for example, if position control that determines the position target value of the die cushion in response to the passage of time from the start of the press machine is adopted, the slide motion that occurs during continuous drawing processing is detected. Since the time delay cannot be absorbed and divided on the die cushion control device side, the upper mold cannot be brought into contact with the workpiece at an optimal timing during preliminary acceleration. In such a case, because the slide movement is delayed, the preliminary acceleration of the die cushion is preceded. Therefore, the upper die comes into contact with the workpiece at a lower position, and the drawing process is completed in a short time. In particular, there is a problem that processing defects are likely to occur. In particular, if a position target value is set to allow the die cushion to wait at a predetermined height at the end of preliminary acceleration, the upper die may come into contact with the workpiece in the standby state, resulting in a large impact. There is a possibility.

  An object of the present invention is to provide a die cushion control device and a die cushion control method capable of reliably bringing a die into contact with a workpiece at an optimal position at the time of preliminary acceleration in the die cushion.

Die cushion control apparatus of a press machine according to claim 1 of the present invention is a die cushion control apparatus of a press machine, a first position command signal output section for outputting a position command signal corresponding to the target position value of the die cushion pad The press detected by the slide position detecting means in each of the subdivision sections obtained by subdividing a predetermined section including a section where the die cushion pad is pre-accelerated, and a slide position detecting means for detecting the slide position of the press machine A second position command signal output unit that outputs a position command signal based on a position matrix that specifies a die cushion pad position corresponding to a machine slide position; and a die cushion position detection unit that detects a position of the die cushion pad; from the die cushion position detecting means and the position target value based on the position command signal A position comparison unit that outputs a position deviation signal corresponding to a deviation from a position detection value based on the position detection signal; and any one of the position command signals of the first position command signal output unit and the second position command signal output unit A first output switching unit that switches whether to output to the position comparison unit; a position control unit that outputs a position speed command signal based on the position deviation signal; and a position speed command signal from the position control unit. A speed control unit that outputs a motor current command signal, and a servo amplifier that supplies a current corresponding to the motor current command signal to an electric servo motor for driving the die cushion.

Die cushion control apparatus of a press machine according to claim 2 of the present invention, the die cushion control apparatus of a press machine according to claim 1, based on the detection signal from the previous SL slide position detection means, said first output A switching signal generation unit that outputs a switching signal to the switching unit is provided.

A die cushion control device for a press machine according to claim 3 of the present invention is the die cushion control device for a press machine according to claim 2 , further outputting a pressure command signal corresponding to a pressure target value of the die cushion pad. A pressure command signal output unit, pressure detection means for detecting the pressure generated on the die cushion pad, a pressure target value based on the pressure command signal, and a pressure detection value based on a pressure detection signal from the pressure detection means A pressure comparison unit that outputs a pressure deviation signal corresponding to the deviation; a pressure control unit that outputs a pressure speed command signal based on the pressure deviation signal; a pressure speed command signal from the pressure control unit and the position control; A position / pressure control switching unit for switching which signal is output to the speed control unit among the position speed command signals from the unit; The use speed command signal, characterized in that a second output switching section for switching whether via the position and pressure control switching unit.

According to a fourth aspect of the present invention, there is provided a die cushion control method for a press machine, wherein a standby step for waiting a die cushion pad driven by an electric servo motor at an upper limit position and a slide of the press machine to be lowered are set in advance. a first position detecting step of detecting that reaches one position, when the slide has reached the first position, the predetermined interval including an interval in which the die cushion pad is preliminarily accelerated by finely divided each subdivision sections a matrix control step of controlling the position the electric servo motor on the basis of the position matrix that specifies the position of the die cushion pad corresponding to the position of the slide detected by the slide position detecting means, before kissing ride, the preliminary acceleration There a second position detecting step for detecting that has reached the second position to end, when the slide has reached the second position, The position of the electric servo motor is controlled so that the position of the die cushion pad follows a preset target position, or the pressure applied to the die cushion pad follows the preset target pressure. And a position / pressure switching control step for controlling the pressure of the electric servomotor.

  According to the present invention, at the time of preliminary acceleration of the die cushion pad, the die cushion pad moves with a predetermined position specified according to the position of the slide as a target. Even if a time delay occurs, the preliminary acceleration of the die cushion pad can always be started at the same timing according to the position of the slide, and each time the preliminary acceleration is performed, the mold on the slide side is placed at the optimum position. The processing accuracy can be improved.

Next, specific embodiments of the die cushion control device according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a press machine 1 according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of the die cushion 13 according to the first embodiment.

  A press machine 1 shown in FIG. 1 includes a slide 4 that is supported by a main body frame 2 so as to be movable up and down and is driven up and down by a slide drive mechanism 3, and a bolster 6 that is disposed opposite to the slide 4 and attached to a bed 5. And. An upper die 7 is attached to the lower surface of the slide 4, and a lower die 8 is attached to the upper surface of the bolster 6. Thus, press work (drawing) is performed on the work 9 disposed between the upper die 7 and the lower die 8 by the lifting and lowering operation of the slide 4.

  Among these configurations, the bed 5 has a built-in die cushion (D / C) 13. The die cushion 13 includes a required die cushion pin 14, a die cushion pad 15 that is supported by the bed 5 so as to be movable up and down in the bed 5, and a die cushion pad drive mechanism 16 that drives the die cushion pad 15 up and down. It is configured with.

  Each die cushion pin 14 is inserted into a hole formed in each of the bolster 6 and the lower mold 8 and penetrating in the vertical direction. The upper end of each die cushion pin 14 is in contact with a blank holder 17 disposed in the recess of the lower mold 8, and the lower end thereof is in contact with the die cushion pad 15.

  Between each side surface of the die cushion pad 15 and the inner wall surface of the bed 5 facing each side surface, one or more guide members (not shown) for guiding the die cushion pad 15 in the vertical direction are provided. Each guide member includes a pair of inner guide and outer guide that engage with each other. The inner guide is attached to each side surface of the die cushion pad 15, and the outer guide is attached to the inner wall surface of the bed 5. Thus, the die cushion pad 15 is supported in the bed 5 so as to be movable up and down.

  As shown in FIG. 2, the die cushion pad drive mechanism 16 includes an electric servo motor 21 as a drive source, a ball screw mechanism 22 as an elevator means for the die cushion pad 15, an electric servo motor 21 and a ball screw mechanism. A winding transmission mechanism 23 and a connecting member 24 arranged in a power transmission path between the die cushion pad 15 and the electric servomotor 21 are configured to be able to transmit each other's power freely.

  The electric servo motor 21 is a rotary AC servo motor having a rotation shaft, and the rotation speed and the rotation force of the rotation shaft are controlled by controlling the motor current (current) i supplied to the electric servo motor 21. It has become. A main body portion of the electric servo motor 21 is fixed to a beam 25 laid between the inner wall surfaces of the bed 5. The electric servomotor 21 is provided with an encoder (die cushion position detecting means) 36. The encoder 36 detects the angle and angular velocity of the rotating shaft of the electric servomotor 21 and outputs the detected values as a motor rotation angle detection signal θ and a motor rotation angular velocity detection signal ω, respectively. The motor rotation angle detection signal θ and the motor rotation angular velocity detection signal ω output from the encoder 36 are input to the controller 41 described later.

  The ball screw mechanism 22 includes a screw portion 26 and a nut portion 27 that is screwed to the screw portion 26. The rotary power input from the nut portion 27 is converted into linear power by the screw portion 26 and output. It has a function to do. The lower end portion of the screw portion 26 is disposed so as to be able to advance and retreat in a space formed in the central portion of the connecting member 24, and the lower end portion of the nut portion 27 is coupled to the upper end portion of the connecting member 24. The connecting member 24 is supported by the beam 25 via a bearing device 28 including required bearings and a bearing housing that accommodates the bearings.

  In the winding transmission mechanism 23, a timing belt 31 is wound between a small pulley 29 fixed to the rotating shaft of the electric servomotor 21 and a large pulley 30 fixed to the lower end portion of the connecting member 24. Is made up of.

  With the above configuration, the rotational power of the electric servomotor 21 is transmitted to the nut portion 27 in the ball screw mechanism 22 via the small pulley 29, the timing belt 31, the large pulley 30, and the connecting member 24, and is transmitted to the nut portion 27. The screw portion 26 in the ball screw mechanism 22 is moved in the vertical direction by the rotational power thus generated, and the die cushion pad 15 is driven up and down. Further, the urging force applied to the die cushion pad 15 is controlled by controlling the motor current i to the electric servomotor 21.

  Incidentally, in this die cushion 13, a plunger rod 80 is connected to the lower end portion of the die cushion pad 15. The plunger rod 80 is slidably supported at its side by a cylindrical plunger guide 82. The plunger guide 82 has a function of guiding the plunger rod 80 and the die cushion pad 15 connected to the plunger rod 80 in the up and down direction. A cylinder 80A having a downward opening is formed in the lower portion of the plunger rod 80, and a piston 81 is slidably accommodated in the cylinder 80A.

  A hydraulic chamber 83 is formed on the inner wall surface of the cylinder 80A and the upper surface of the piston 81, and the hydraulic chamber 83 is filled with pressure oil. The axial center of the hydraulic chamber 83 is the same as that of the plunger rod 80 and the ball screw mechanism 22. The pressure oil port of the hydraulic chamber 83 is connected to a hydraulic circuit, and pressure oil is exchanged between the hydraulic chamber 83 and the hydraulic circuit. The pressure oil in the hydraulic chamber 83 relaxes the impact generated when the upper mold 7 and the work 9 come into contact with each other, and is discharged to the tank when the hydraulic pressure exceeds a predetermined value. The pressure oil in the hydraulic chamber 83 has such an overload protection function.

  The lower end of the piston 81 is in contact with the upper end of the screw portion 26 in the ball screw mechanism 22. A spherical concave surface 81A is formed at the lower end of the piston 81, and a spherical convex surface is formed at the upper end of the screw portion 26 facing the concave surface 81A. On the contrary, a convex surface may be formed at the lower end of the piston 81 and a concave surface may be formed at the upper end of the screw portion 26. A rod-like member such as the screw portion 26 is strong against an axial force acting on the end portion, but is weak against a bending moment. If the upper end of the threaded portion 26 is spherical, even if the die cushion pad 15 is inclined and a bending moment is generated at the upper end of the threaded portion 26, only the axial force acts on the entire threaded portion 26. Such a structure can prevent the screw portion 26 from being damaged by the eccentric load.

  In the die cushion 13, the pressure in the hydraulic chamber 83 is detected in the hydraulic circuit described above. The port of the hydraulic chamber 83 communicates with a pipe line 85 constituting a hydraulic circuit, and a pressure gauge 93 is provided in the middle of the pipe line 85. The pressure gauge 93 detects the pressure in the hydraulic chamber 83, that is, the load generated on the die cushion pad 15. A pressure detection signal Pr is output from the pressure gauge 93 toward the controller 41.

  Next, the configuration of the die cushion control device 40 that controls the die cushion 13 will be described below with reference to the functional block diagram of FIG. 3 and the control block diagram of FIG.

  The die cushion control device 40 shown in FIGS. 3 and 4 includes a controller 41 and a servo amplifier 42 that supplies a motor current i corresponding to a motor current command signal ic output from the controller 41 to the electric servomotor 21. It has.

  Although not described in detail, the controller 41 is mainly composed of an input interface for converting and shaping various input signals, a microcomputer, a high-speed numerical arithmetic processor, and the like, and performs arithmetic on input data according to a predetermined procedure. A computer apparatus that performs a logical operation and an output interface that converts the operation result into a control signal and outputs the control signal. The controller 41 includes a die cushion pad position calculation unit 43, a die cushion pad speed calculation unit 44, a first position command signal output unit 45, a position comparison unit 46, a position control unit 47, a pressure command signal output unit 48, and a pressure comparison. 49, pressure control unit 50, position / pressure control switching unit 51, speed comparison unit 52, speed control unit 53, second position command signal output unit (position command signal output unit) 74, first output switching unit 75, first Various output switching units 76 and switching signal generation unit 77 are provided. These functional units are formed by software or the like processed by the computer.

  The die cushion pad position calculation unit 43 receives a motor rotation angle detection signal θ from an encoder 36 attached to the electric servomotor 21, and the die cushion pad 15 having a predetermined relationship with the motor rotation angle based on this input signal. And a result of outputting the result as a die cushion pad position detection signal (position detection signal) hr.

  The die cushion pad speed calculation unit 44 receives the motor rotation angular speed detection signal ω from the encoder 36, and the speed (elevating speed) of the die cushion pad 15 having a predetermined relationship with the motor rotation speed based on this input signal. And outputs the result as a die cushion pad speed detection signal υr.

  The first position command signal output unit 45 obtains a position target value of the die cushion pad 15 by referring to a preset position pattern 54, and generates a position command signal hc based on the obtained position target value. It has a function to output. Here, the position pattern 54 indicates a desired correspondence between time and die cushion pad position.

  Specifically, as shown in FIG. 5, in the position pattern 54, the die cushion pad 15 is positioned at the standby position h1 until time t1, and preliminary acceleration is performed toward the position h2 from here until time t2. At a predetermined time constant, and after preliminary acceleration, it is further lowered from time t2 to time t21 to position h21 with a different time constant, waits at this position h21 until time t3, and decreases at time t3. Positioned at the position h3 corresponding to the dead center position, until the time t4 is reached, the position h3 is maintained and the bottom dead center locking is performed.From time t4 to time t5, the auxiliary lift is raised, and then the standby position h1 Is set to return to

  In FIG. 5, the position pattern 54 from time t12 to time t3 is drawn with a two-dot chain line, and the other portions are drawn with a solid line. The solid line portion represents the actual movement locus of the die cushion pad 15. Therefore, between the time t12 and the time t3, the die cushion pad 15 goes down through a lower position together with the slide 4 against the position target of the position pattern 54.

  The position comparison unit 46 includes a position command signal hc output from the first position command signal output unit 45 or the second position command signal output unit 74 via the first output switching unit 75, and a die cushion pad position calculation unit 43. Is compared with the die cushion pad position detection signal hr, and a position deviation signal eh is output.

The position control unit 47 includes a coefficient unit 55 that receives the position deviation signal eh from the position comparison unit 46, multiplies the input signal by a predetermined position gain K1, and outputs a position corresponding to the position deviation signal eh. It has a function to generate and output the industrial speed command signal υhc.

The pressure command signal output unit 48 obtains a pressure (cushion pressure) target value generated in the die cushion pad 15 by referring to a preset pressure pattern 56, and a pressure command based on the obtained pressure target value. It has a function to generate and output the signal Pc. Here, the pressure pattern 56 indicates a desired correspondence between time and the pressure generated in the die cushion pad 15.

  Specifically, as shown in FIG. 5, the pressure pattern 56 is set to a predetermined pressure value P <b> 1 until time t <b> 12 when the upper die 7 contacts the workpiece 9. This predetermined value P1 is set to a value that is higher by a predetermined ratio than the preload of the die cushion pad 15, so that, in a state before the upper die 7 is in contact with the workpiece 9, a predetermined pressure from the pressure comparison unit 49 described below is set. The pressure deviation signal ep is generated. Next, in the range from time t12 to time t3 when the upper die 7 is in contact with the workpiece 9, the pressure value 56 is set to a pressure value P2 optimum for the drawing, and the time t3 Thereafter, the pressure value P3 is set to be a large pressure value.

  The pressure comparison unit 49 has a function of comparing the pressure command signal Pc from the pressure command signal output unit 48 with the pressure detection signal Pr from the pressure gauge 93 and outputting a pressure deviation signal ep.

The pressure control unit 50 receives the pressure deviation signal ep from the pressure comparison unit 49, multiplies the input signal by a predetermined proportional gain K2, and outputs the coefficient unit 71 and the pressure deviation signal ep from the pressure comparison unit 49. An integrator 72 that inputs and integrates and outputs the input signal (the symbol s in the block is a Laplace operator), and an output signal from the integrator 72 is input and a predetermined integral gain K3 is input to the input signal. And a coefficient unit 73 that multiplies and outputs, and has a function of generating and outputting a pressure speed command signal υpc by adding the output signal from the coefficient unit 73 to the output signal from the coefficient unit 71.

  In this pressure control unit 50, a pressure deviation signal is transmitted from the pressure control unit 50 by performing a proportional + integral operation (PI operation) that combines a proportional operation (P operation) and an integration operation (I operation). A pressure speed command signal υpc that is large enough to match ep and increases as long as there is a pressure deviation signal ep is output, so that the detected pressure matches the target pressure quickly and accurately. .

  The position / pressure control switching unit 51 switches between position control for controlling the position of the die cushion pad 15 and pressure control for controlling the pressure generated in the die cushion pad 15. A switch 60 for switching the connection with the c contact and a position / pressure comparison unit 61 for selecting a switching operation of the switch 60 are provided.

  When the contact b is connected to the contact a by the switch 60 (hereinafter, this connection operation is referred to as “ba contact connection operation”), the position speed command signal υhc from the position controller 47 compares the speed. On the other hand, when the b contact and the c contact are connected by the switch 60 (hereinafter, this connection operation is referred to as “bc contact connection operation”), the pressure control unit 50 The speed command signal υpc for pressure flows to the speed comparison unit 52.

  The position / pressure comparison unit 61 compares the pressure speed command signal υpc from the pressure control unit 50 with the position speed command signal υhc from the position control unit 47, and selects the smaller one of the two. Has been. That is, if the position speed command signal υhc is small, position control is performed, and if the pressure speed command signal υpc is small, pressure control is performed.

When the position control is selected by the switching operation by the position / pressure control switching unit 51, the speed comparison unit 52 receives the position speed command signal υhc from the position control unit 47 and the die cushion pad speed calculation unit 44. When the pressure control is selected by the switching operation by the position / pressure control switching unit 51 by comparing with the die cushion pad speed detection signal υr, and the pressure deviation signal ev is output. It has a function of comparing the speed command signal υpc and the die cushion pad speed detection signal υr from the die cushion pad speed calculation unit 44 and outputting a speed deviation signal ev.

According to the present embodiment, at the time of pressure control, a pressure speed command signal υpc from the pressure control unit 50 that corresponds to the pressure deviation signal ep and increases as long as the pressure deviation signal ep is present. Is output, the pressure deviation can be reduced quickly and reliably. Therefore, the accuracy of pressure control can be improved.

The speed control unit 53 receives the speed deviation signal ev from the speed comparison unit 52, multiplies the input signal by a predetermined proportional gain K4, and outputs the coefficient unit 62 and the speed deviation signal ev from the speed comparison unit 52. An integrator 63 (symbol s in the block is a Laplace operator) for inputting and integrating the input signal, and an output signal from the integrator 63 is input and a predetermined integral gain K5 is input to the input signal. And a coefficient unit 64 that multiplies and outputs the signal, and adds the output signal from the coefficient unit 64 to the output signal from the coefficient unit 62 to generate a motor current command signal (torque command signal) ic
It has a function to output.

Also in the speed control unit 53, a proportional deviation + integral operation (PI operation) combining a proportional operation (P operation) and an integration operation (I operation) is performed, so that the speed control unit 53 receives a speed deviation signal. A motor current command signal ic having a magnitude corresponding to ev and increasing as long as the speed deviation signal ev is present is output, and the detected speed is quickly and accurately matched to the target speed. In this way, stable position / pressure control can be performed.

The second position command signal output unit 74 obtains a position target value of the die cushion pad 15 by referring to a preset position matrix 78, and generates a position command signal hc based on the obtained position target value. It has a function to output. Here, the position matrix 78 indicates a desired correspondence between the slide position and the die cushion pad position. That is, in the first position command signal output section 45 described above, generates a position command signal hc in accordance with the elapsed time on the basis of the position pattern 54 has been output, in the second place置指command signal output unit 74, A position command signal hc corresponding to the position of the slide 4 is generated and output.

  Specifically, as shown in FIGS. 6 and 7, the position matrix 78 includes the actual position of the slide 4 (or the rotation angle of the main shaft of the press machine 1 and the servo motor that drives the same) P0 (first position). The positions A0 to An of the die cushion pad 15 corresponding to ~ Pn (second position) are designated as position target values. In this embodiment, position control using such a position matrix 78 is applied during preliminary acceleration of the die cushion pad 15. That is, the positions P0 to Pn are positions obtained by dividing a predetermined section including the preliminary acceleration section at equal time intervals, and in this way, the die cushion pad 15 synchronized with the position of the slide 4 at the time of preliminary acceleration. Position control can be performed. Therefore, by setting the positions Pn and An at the same position where the upper die 7 and the workpiece 9 are in contact with each other, the slide 4 is moved to the position Pn even when the operation of the slide 4 is delayed due to continuous drawing. At any time, the die cushion 14 can be positioned at the position An having the same height, and the upper die 7 can be brought into contact with the workpiece 9 at the optimum height positions Pn and An at each preliminary acceleration.

  The first output switching unit 75 functions as a switch that is switched by a press signal S from a press signal generation unit 10 provided in the press machine 1, and includes contacts d, e, and f in terms of a control block. In the first output switching unit 75, during the ed contact connection operation when the contact e and the contact d are connected, the position command signal hc from the first position command signal output unit 45 is compared as described above. Is output to the unit 46. On the other hand, the position detection signal hc from the second position command signal output unit 74 is output to the position comparison unit 46 during the ef contact connection operation when the contact e and the contact f are connected.

  The second output switching unit 76 also functions as a switch that is switched by a press signal S from the press signal generation unit 10 provided in the press machine 1 and includes contacts g, h, and i. In the second output switching unit 76, during the h-g contact connection operation when the contact h and the contact g are connected, the position speed command signal υhc from the position control unit 47 is the position / pressure control as described above. It is output to the switching unit 51. On the other hand, at the time of the hi contact connecting operation when the contact h and the contact i are connected, the position speed command signal υhc is directly output to the speed comparison unit 52, and the position / pressure control switching unit 51. Is not output.

  The switching signal generation unit 77 has a function of outputting a switching signal to the first and second output switching units 75 and 76 based on the press signal S from the press signal generation unit 10. Here, the press signal S generated by the press signal generation unit 10 is related to the slide position, and in this embodiment, a linear scale (slide position detecting means) provided across the slide 4 and the main body frame 2 is used. ) 11 based on the position signal λ from 11. That is, the press signal generation unit 10 determines which height position of the slide 4 is P0 to Pn based on the position signal λ, and outputs a press signal S corresponding to the position.

  When the switching signal generation unit 77 inputs the press signal S corresponding to the position P0, the switching signal is output to the first output switching unit 75 so as to perform the ef contact connection operation, and the second output. A switching signal is output to the switching unit 76 so as to perform the hi contact connection operation.

The servo amplifier 42 includes a current comparison unit 65, a current control unit 66, and a current detection unit 67. In the servo amplifier 42, the current detector 67 detects the motor current i supplied to the electric servomotor 21, and outputs the detected value as a motor current detection signal ir. Current comparison unit 65 compares motor current command signal ic from speed control unit 53 with motor current detection signal ir from current detection unit 67 and outputs motor current deviation signal ei. The current control unit 66 controls the motor current i to the electric servomotor 21 based on the motor current deviation signal ei from the current comparison unit 65.

  In the die cushion control device 40 configured as described above, as shown in FIGS. 5 and 7, the position control in the position / pressure switching control, that is, until the slide 4 reaches the position P0 from the start of processing, that is, Position control is performed by the position command signal hc using the position pattern 54, and the position of the slide 4 is between the positions P0 to Pn, that is, the preliminary acceleration sections A0 to An of the die cushion pad 15 (however, as shown in FIG. 7). In the interval from position A0 to A3, the position control using the position matrix 78 is performed. In the section where the drawing process is performed past the positions Pn and An, the pressure control in the position / pressure switching control is performed, and after the position h3 corresponding to the bottom dead center, the position control in the position / pressure switching control is performed again. Return.

  At this time, the position control is performed after the slide 4 starts processing until it reaches the position P0 by the following operation. First, in this section, the ed contact connection operation and the hg contact connection operation are performed in the first and second output switching units 76 and 77, respectively. The position target by the position pattern 54 of the die cushion pad 15 in the section is the standby position h1, whereas the die cushion pad 15 is actually waiting at the standby position h1. The deviation signal eh is 0 “zero”, and the position speed command signal υhc generated based on the deviation signal eh is also 0 “zero”. On the other hand, the target pressure value based on the pressure pattern 56 in this section is set to a predetermined pressure deviation signal ep because the predetermined pressure value P1 is set despite the state before drawing. Is generated by the pressure comparator 49, and a predetermined pressure speed command signal υpc is generated based on the generated pressure. Therefore, by comparing the predetermined pressure speed command signal υpc with the position speed command signal υhc which is 0, the position / pressure control switching unit 51 selects the position speed command signal υhc, and the position pattern 54 Control is done.

  When the slide 4 is in the positions P0 to Pn, first, when the switching signal generation unit 77 inputs the position P0, the operations in the first and second output switching units 76 and 77 are respectively connected to the ef contact. Switch to operation, hi contact connection operation. By this switching, the second position command signal output unit 74 outputs a position command signal hc that targets positions A0 to An corresponding to the positions P0 to Pn based on the position matrix 78. The position speed command signal υhc based on the position command signal hc is directly output to the speed comparison unit 52 without being compared with the pressure speed command signal υpc, so that position control using the position matrix 78 is performed. It will be.

  The reason why the pressure control is selected in the section of drawing processing past the positions Pn and An is as follows. In the drawing section, the first and second output switching units 76 and 77 perform the ed contact connection operation and the hg contact connection operation by the switching signal from the switching signal generation unit 77, respectively. In the section where the drawing process is performed, pressure feedback is performed so that the pressure applied to the die cushion pad 15 becomes a pressure target based on the pressure pattern 56, so that the pressure deviation signal ep generated in the pressure comparison unit 49 is relatively low. The pressure speed command signal υpc generated by the pressure controller 50 is also small. On the other hand, since the position pattern 54 in the drawing section is set to a position above the descending locus even though the die cushion pad 15 is lowered together with the slide 4 (FIG. 5). The position deviation signal eh and the position speed command signal υhc are increased. Therefore, the position / pressure control switching unit 51 selects the pressure speed command signal υpc, and pressure control using the pressure pattern 56 is performed.

  The following operation returns to the position control in the position / pressure switching control again after the position h3 corresponding to the bottom dead center. First, the operation states in the first and second output switching units 76 and 77 are the ed contact connection operation and the hg contact connection operation. At the position h3, the position target based on the position pattern 54 is still set to the position h3, and the position deviation signal eh and the position speed command signal υhc are relatively small. However, at the position h3 which is the bottom dead center, the pressure applied to the die cushion pad 15 is released because the slide 4 starts to rise, so the actual pressure is substantially zero, but the pressure target at the position h3 based on the pressure pattern 56 is The pressure P3 (FIG. 5) is set excessively, and the pressure deviation signal ep and the pressure speed command signal υpc both increase. Therefore, the smaller position speed command signal υhc is selected, and the position control using the position pattern 54 is switched.

Hereinafter, the position control by the position pattern 54, the pressure control by the pressure pattern 56, and the position control by the position matrix 78 will be briefly described with reference to the flowchart of FIG.
First, when the control program for the die cushion 13 is started, the die cushion control device 40 executes position / pressure switching control (ST1: position / pressure switching control process). Specifically, position control using the position pattern 54 is executed. During execution of this position control, the die cushion control device 40 first waits the die cushion pad 15 at the standby position h1 that is the upper limit position (standby step). The switching signal generator 77 of the die cushion device 40 receives the press signal S from the press signal generator 10 (ST2) and monitors whether the slide 4 has reached the position P0 (ST3: first position detection). Process).

  When the slide 4 reaches the position P0, the switching signal generation unit 77 outputs a switching signal to the first output switching unit 75, and switches the connection operation from the ed contact connection operation to the ef contact connection operation. A position command signal hc based on the matrix 78 in the second position command signal output unit 74 is output. At the same time, the switching signal generation unit 77 outputs a switching signal to the second output switching unit 76, switches the connection operation from the hg contact connection operation to the hi contact connection operation, and performs the second position command. A position speed command signal υhc based on the position command signal hc from the signal output unit 74 is directly output to the speed comparison unit 52, bypassing the position / pressure control switching unit 51 (ST4, 5). As a result, the die cushion control device 40 executes position control using the position matrix 78 (ST6: matrix control step), and performs preliminary acceleration of the die cushion pad 15.

  Thereafter, the switching signal generator 77 monitors whether the slide 4 has passed the position Pn based on the press signal S (ST7: second position detection step). When the position Pn is passed, the switching signal generator 77 determines that the preliminary acceleration has ended, and returns the connection operation from the ef contact connection operation to the ed contact connection operation, and outputs the first position command signal output. A position command signal hc based on the position pattern 54 in the unit 45 is output. At the same time, the switching signal generation unit 77 outputs a switching signal to the second output switching unit 76 to return the connection operation from the hi contact connection operation to the hg contact connection operation. A position speed command signal υhc based on the position command signal hc from the position command signal output unit 45 is output to the position / pressure control switching unit 51 (ST8, 9).

  Thus, returning to the position / pressure switching control step of ST1, the die cushion control device 40 executes position / pressure switching control. Specifically, the position / pressure control switching unit 51 compares the position speed command signal υhc with the pressure speed command signal υpc based on the pressure pattern 56, and as a result, selects the pressure speed command signal υpc. Execute pressure control and perform drawing. Thereafter, when the slide 4 and the die cushion pad 15 reach the bottom dead center position, the pressure control is switched to the position control, the bottom cushion is locked by the die cushion pad 15, and then the standby position h1 is again set. Repeat after ST2.

The best configuration, method, and the like for carrying out the present invention have been disclosed above, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of quantity, other details, and the like.
Therefore, the description limited to the shape, quantity, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  For example, in the embodiment, a pressure gauge provided in the hydraulic circuit is used as a means for detecting the pressure applied to the die cushion pad, but a strain gauge provided on the side surface of the die cushion pad may be used. Also good. The position detection means in the present invention is not limited to the encoder provided in the electric servo motor for driving the die cushion, and may be a linear scale provided between the die cushion pad and the bed. Furthermore, the electric servo motor is not limited to the rotary type, and may be a direct acting type such as a linear servo motor. Further, the slide position detecting means is not limited to a linear scale, and may be an encoder provided in an electric servo motor for driving a press or a rotation angle of a main shaft driven by this electric servo motor. .

In the above embodiment, the die cushion control device is configured to switch between the position control based on the position pattern and the pressure control based on the pressure pattern except during the preliminary acceleration of the die cushion. It is sufficient that the position control is used, and even when the position control using the position matrix is performed through the stroke, it is included in the present invention. Even when the position control and the pressure control are switched, the position control may be performed entirely using the position matrix, or the position control based on the position pattern may be omitted.

  INDUSTRIAL APPLICABILITY The present invention can be used for a die cushion control device for controlling a die cushion used in a press machine that performs drawing or the like, and can be suitably used particularly as a die cushion control device for a die cushion driven by an electric servo motor.

1 is a schematic configuration diagram of a press machine according to an embodiment of the present invention. The schematic block diagram of the die cushion which concerns on the said embodiment. The functional block diagram explaining the structure of a die cushion control apparatus. The control block diagram explaining the structure of a die cushion control apparatus. The figure which shows a position pattern and a pressure pattern. The figure which shows a position matrix. Explanatory drawing for demonstrating position control using a position matrix. The flowchart for demonstrating operation | movement of a die cushion control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Press machine, 4 ... Slide, 9 ... Workpiece, 11 ... Slide position detection means, 13 ... Die cushion, 15 ... Die cushion pad, 21 ... Electric servo motor, 36 ... Encoder which is die cushion position detection means, 40 ... Die cushion control device, 42 ... servo amplifier, 45 ... first position command signal output unit, 46 ... position comparison unit, 47 ... position control unit, 48 ... pressure command signal output unit, 49 ... pressure comparison unit, 50 ... pressure control 51, position / pressure control switching unit, 53 ... speed control unit, 74 ... second position command signal output unit which is a position command signal output unit, 77 ... switching signal generation unit, 78 ... position matrix, 93 ... pressure detection Pressure gauge as means, ic ... motor current command signal, i ... motor current as current, hc ... position command signal, hr ... die cushion pad position as position detection signal Out signal, eh ... position deviation signal, υhc ... position-speed command signal.

Claims (4)

In the die cushion control device (40) of the press machine (1),
A first position command signal output unit (45) for outputting a position command signal according to a position target value of the die cushion pad (15);
Slide position detecting means (11) for detecting the position of the slide (4) of the press machine (1);
Corresponding to the slide position of the press machine (1) detected by the slide position detecting means (11) in each subdivision section obtained by subdividing a predetermined section including a section where the die cushion pad (15) is pre-accelerated. A second position command signal output unit (74) for outputting a position command signal based on a position matrix (78) for designating the die cushion pad position,
Die cushion position detecting means (36) for detecting the position of the die cushion pad (15);
A position comparison unit (46) for outputting a position deviation signal according to a deviation between a position target value based on the position command signal and a position detection value based on a position detection signal from the die cushion position detection means (36);
A first output switching section (75) for switching which position command signal of the first position command signal output section (45) and the second position command signal output section (74) is output to the position comparison section (46). )When,
A position controller (47) for outputting a position speed command signal based on the position deviation signal;
A speed control unit (53) for outputting a motor current command signal based on the position speed command signal from the position control unit (47);
A die cushion control device for a press machine (1), comprising: a servo amplifier (42) for supplying a current corresponding to the motor current command signal to an electric servomotor (21) for driving the die cushion. In the die cushion control device (40) of the press machine (1) according to claim 1 ,
A press machine comprising a switching signal generation unit (77 ) for outputting a switching signal to the first output switching unit (75) based on a detection signal from the slide position detection means (11). 1) Die cushion control device. In the die cushion control device (40) of the press machine (1) according to claim 2 ,
A pressure command signal output unit (48) for outputting a pressure command signal corresponding to a pressure target value of the die cushion pad (15);
Pressure detecting means (93) for detecting the generated pressure applied to the die cushion pad (15);
A pressure comparison unit (49) for outputting a pressure deviation signal corresponding to a deviation between a pressure target value based on the pressure command signal and a pressure detection value based on a pressure detection signal from the pressure detection means (93);
A pressure controller (50) for outputting a pressure speed command signal based on the pressure deviation signal;
Which signal is output to the speed control unit (53) from the pressure speed command signal from the pressure control unit (50) and the position speed command signal from the position control unit (47). A switching position / pressure control switching section (51);
A die for a press machine (1), comprising: a second output switching unit (76) for switching whether or not the position speed command signal passes through a position / pressure control switching unit (51). Cushion control device. In the die cushion control method of the press machine (1),
A standby step of waiting the die cushion pad (15) driven by the electric servo motor (21) at the upper limit position;
A first position detecting step for detecting that the slide (4) of the descending press machine (1) has reached a preset first position;
When the slide (4) reaches the first position , the slide position detecting means (11) detects each subdivision section obtained by subdividing a predetermined section including a section where the die cushion pad (15) is pre-accelerated. A matrix control step for controlling the position of the electric servomotor (21) based on a position matrix (78) that specifies the position of the die cushion pad (15) corresponding to the position of the slide (4) to be performed ;
Before Kiss Ride (4), and a second position detecting step for detecting that the pre-acceleration has reached the second position to end,
When the slide (4) reaches the second position, the position of the electric servo motor (21) is controlled so that the position of the die cushion pad (15) follows a preset target position, or A position / pressure switching control step for performing pressure control of the electric servo motor (21) so that the pressure applied to the die cushion pad (15) follows a preset target pressure. A die cushion control method for the press machine (1).

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