Die buffer device and control method of die buffer device

Abstract

Provided are a die buffer device that is not restricted by the configuration of a die and a control method for the die buffer device. The die buffer device (200) includes four hydraulic cylinders that support a buffer pad (210), a die buffer load controller (308) that controls each hydraulic cylinder and causes the buffer pad (210) to generate a die buffer load, and a die buffer position controller (304) that controls each hydraulic cylinder and controls the position of the buffer pad (210). When only a left component is produced by using a left die (120L) through a stamping machine, the die buffer load controller (308) performs die buffer load control on the two hydraulic cylinders on the left, and the die buffer position controller (304) performs die buffer position control on the two hydraulic cylinders on the right.

Description

Technical Field

[0001] The present invention relates to a die buffer device and a control method of the die buffer device, and in particular to a die buffer device capable of freely configuring a die and a control method of the die buffer device. Background Art

[0002] Patent Document 1 describes a die cushion device in which a plurality of cushion pads are supported by a plurality of drive shafts (hydraulic cylinders), respectively, and a required die cushion load can be applied to each hydraulic cylinder, or a cushion pad standby position can be changed (thereby changing the die cushion stroke).

[0003] In addition, in Patent Document 1 Figure 5 A press machine equipped with a plurality of independent dies and a die cushion device provided with a plurality of cushion pads corresponding to each of the plurality of dies are described.

[0004] However, there is an expectation that Fig.16 As shown, two products are produced using a press machine equipped with a plurality of (two) dies 120L and 120R, and then one die 120R is removed and the product is produced using only the other die 120L.

[0005] For example, in an automated production line (Tandem line) responsible for mass production of automobile bodies, after completing production of a specified amount of two products (two on the left and two on the right) in one cycle by using different left and right molds, if one of the products is found to be defective, it is sometimes desirable to continue production of the one product corresponding to the number of defective products.

[0006] In such Fig.16 When the mold 120R represented by the dotted line is removed as shown and only the mold 120L is used to produce the product, the mold 120L is arranged at a position offset on (the projection surface of) the buffer pad 210 supported by four hydraulic cylinders (220LF, 220LB, 220RF, 220RB) at the left front, left rear, right front, and right rear.

[0007] In this case, if Fig.16 As shown by the arrows, the mold cushion load control in the four hydraulic cylinders (220LF, 220LB, 220RF, 220RB) acts on the cushion pad 210 so that the cushion pad 210 moves to Fig.16 The moment of rotation in the direction of the arrow, the cushion 210 becomes tilted (at Fig.16 On the top, the right side of the buffer pad 210 is lifted).

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2016-221564

[0011] When the mold is arranged at a position offset on the cushion pad as described above, a problem of the cushion pad being tilted occurs, and therefore there is a limit to the arrangement of the mold.

[0012] As a result, for example, in the case where two dies are mounted on a stamping machine in order to simultaneously produce two products, even if only one product needs to be produced after a specified amount of production in order to adjust the production number accompanied by a different number of defectives, there is a problem of waste caused by producing two products. Summary of the invention

[0013] Problems to be solved by the invention

[0014] The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to provide a die cushion device and a control method of the die cushion device which are not restricted by the arrangement of the die.

[0015] Means for solving problems

[0016] In order to achieve the above-mentioned purpose, a mold buffer device according to one embodiment of the present invention is characterized in that the mold buffer device comprises: a plurality of cushion lifting units, which have a plurality of drive shafts for supporting cushions and drive each drive shaft to lift the cushions; a mold buffer load controller, which controls each drive shaft of the plurality of cushion lifting units respectively so that the cushions generate a mold buffer load; a mold buffer position controller, which controls each drive shaft of the plurality of cushion lifting units respectively so as to control the position of the cushion; and a selector, which independently selects, for each of the drive shafts of the plurality of cushion lifting units, whether to be a first drive shaft for performing mold buffer load control based on the mold buffer load controller or a second drive shaft for not performing mold buffer load control based on the mold buffer load controller, wherein in a specific mold buffer load control process, the mold buffer load controller controls only the first drive shaft selected by the selector.

[0017] According to one embodiment of the present invention, for each of the driving shafts of the plurality of cushion lifting units, it is independently selected whether to be set as the first driving shaft for performing mold buffer load control based on the mold buffer load controller, or to be set as the second driving shaft for not performing mold buffer load control based on the mold buffer load controller. The selection of whether to set as the first driving shaft or the second driving shaft for each of the plurality of cushion lifting units is preferably determined based on the area where the mold is configured on the projection surface of the cushion. For example, when there is no mold on the projection surface of the driving shaft, the driving shaft can be selected as the second driving shaft. Furthermore, in a specific mold buffer load control process, the mold buffer load controller controls only the first driving shaft, and does not perform mold buffer load control on the second driving shaft. As a result, it is possible to prevent the second driving shaft from generating a mold buffer load that tilts the cushion, and to perform good mold buffer load control on the cushion.

[0018] In another embodiment of the mold buffer device of the present invention, the feature is that the selector independently selects, for each of the driving shafts of the multiple buffer pad lifting units, whether to be set as a first driving shaft for performing mold buffer load control based on the mold buffer load controller, or to be set as a second driving shaft for performing mold buffer position control based on the mold buffer position controller, and in the specific mold buffer load control process, the mold buffer load controller controls the first driving shaft selected by the selector, and the mold buffer position controller controls the second driving shaft selected by the selector.

[0019] According to another aspect of the present invention, the second drive shaft selected as the drive shaft not to perform the die cushion load control is controlled by the die cushion position controller, thereby preventing the second drive shaft from generating a die cushion load that tilts the cushion pad.

[0020] In another embodiment of the present invention, the mold buffer device is characterized in that the mold buffer device further includes a plurality of mold buffer position detectors, which detect the positions of the cushion pad in the lifting direction corresponding to the positions of the driving shafts of the plurality of cushion pad lifting units, and respectively output position detection values ​​indicating the detected positions, and in the specific mold buffer load control process, the mold buffer position controller controls the second driving shaft based on the position detection value detected by the mold buffer position detector corresponding to the first driving shaft. Thus, the position of the second driving shaft controlled by the mold buffer position controller can be made consistent with the position of the first driving shaft controlled by the mold buffer load controller, so that the cushion pad can be prevented from tilting.

[0021] In another embodiment of the mold buffer device of the present invention, it is preferred that the mold buffer position controller uses as a target value a position detection value detected by a mold buffer position detector corresponding to the first drive shaft adjacent to the second drive shaft, or uses as a target value an average value of two or more position detection values ​​detected by a plurality of mold buffer position detectors corresponding to a plurality of the first drive shafts.

[0022] In the die cushion device of another embodiment of the present invention, preferably, in the specific die cushion load control step, the die cushion position controller controls the second drive shaft so as to be within ±2 mm relative to the target value. This is because the inclination of the cushion pad is controlled within an allowable range.

[0023] In another embodiment of the mold buffer device of the present invention, it is preferred that the plurality of cushion lifting units respectively include a plurality of servo motors driving each drive shaft, and the mold buffer position controller calculates the torque command signal of the servo motor corresponding to the second drive shaft based on the target value and the position detection value of the mold buffer position detector corresponding to the second drive shaft, and adds a signal proportional to the signal obtained by differentiating the target value in time, or a signal proportional to the speed of the sliding part of the stamping machine to the calculated torque command signal, so that it is within ±2mm relative to the target value. A signal proportional to the signal obtained by differentiating the target value in time, or a signal proportional to the speed of the sliding part of the stamping machine is added to the calculated torque command signal as a feedforward compensation amount, thereby compensating for the phase delay amount, and position control can be performed in a manner that is within ±2mm relative to the target value.

[0024] In another embodiment of the mold buffer device of the present invention, it is preferred that the multiple buffer pad lifting units respectively include multiple servo motors driving each drive shaft, and the mold buffer position controller calculates the torque command signal of the servo motor corresponding to the second drive shaft based on the target value and the position detection value of the mold buffer position detector corresponding to the second drive shaft, and adds to the calculated torque command signal a signal obtained by multiplying a signal proportional to a signal obtained by differentiating the target value in time or a signal proportional to the speed of a sliding part of a stamping machine by a phase lead compensation element, so that it is within ±2 mm relative to the target value. A signal proportional to a signal obtained by differentiating a target value in time, or a signal proportional to the speed of a sliding part of a stamping machine, is multiplied by a phase advance compensation element and added as a feedforward compensation amount to the calculated torque command signal, thereby compensating for the phase delay amount. In particular, when the signal obtained by differentiating a target value in time or the speed of a sliding part of a stamping machine changes sharply, it contains specific high-frequency components, but the phase advance compensation element plays a role of compensating in such a way that the position deviation becomes extremely small.

[0025] In a die cushion device according to another embodiment of the present invention, it is preferred that the die cushion device includes a plurality of angular velocity detectors for respectively detecting the rotational angular velocity of the plurality of servo motors, and the die cushion position controller includes a stabilization controller for using the angular velocity signals respectively detected by the plurality of angular velocity detectors as angular velocity feedback signals. The stabilization controller plays a role in improving a phase delay of an open-loop transfer function (open loop) of a die cushion position control system from a die cushion position command signal including a target value in a specific die cushion load control process to a position detection value, thereby stabilizing the position control function.

[0026] In another embodiment of the mold buffer device of the present invention, the feature is that the multiple buffer pad lifting units include: multiple hydraulic cylinders, which include piston rods functioning as respective drive shafts; and multiple hydraulic pumps / motors, which allow working fluid to act on the mold buffer load generating side pressurization chambers of the multiple hydraulic cylinders, and the multiple servo motors are connected to the multiple hydraulic pump / motor shafts.

[0027] Another embodiment of the invention is a control method for a mold buffer device, the mold buffer device comprising: a plurality of cushion lifting units, each having a plurality of drive shafts for supporting a cushion, and each driving shaft is driven to lift the cushion; a mold buffer load controller, which controls each drive shaft of the plurality of cushion lifting units to cause the cushion to generate a mold buffer load; and a mold buffer position controller, which controls each drive shaft of the plurality of cushion lifting units to control the position of the cushion, the control method for the mold buffer device being characterized in that the control method for the mold buffer device comprises the following steps: independently selecting, by a selector, for each of the drive shafts of the plurality of cushion lifting units, whether to be a first drive shaft for performing mold buffer load control based on the mold buffer load controller or a second drive shaft for not performing mold buffer load control based on the mold buffer load controller; and in a specific mold buffer load control process, controlling only the first drive shaft by the mold buffer load controller.

[0028] In another embodiment of the control method of the mold buffer device of the present invention, it is characterized in that, in the step of selecting by the selector, for each of the driving shafts of the multiple buffer pad lifting units, it is independently selected whether to be set as a first driving shaft for performing mold buffer load control based on the mold buffer load controller, or to be set as a second driving shaft for performing mold buffer position control based on the mold buffer position controller, and in the specific mold buffer load control process, the first driving shaft is controlled by the mold buffer load controller, and the second driving shaft is controlled by the mold buffer position controller.

[0029] In another embodiment of the control method of the mold buffer device of the present invention, the mold buffer device is characterized in that the mold buffer device also has a plurality of mold buffer position detectors, which detect the positions of the cushion pads in the lifting direction corresponding to the positions of the driving shafts of the plurality of cushion pad lifting units, and respectively output position detection values ​​representing the detected positions. In the specific mold buffer load control process, the mold buffer position controller controls the second driving shaft based on the position detection value detected by the mold buffer position detector corresponding to the first driving shaft.

[0030] In another embodiment of a control method for a mold buffer device of the present invention, it is preferred that the mold buffer position controller uses as a target value a position detection value detected by a mold buffer position detector corresponding to the first drive shaft adjacent to the second drive shaft, or uses as a target value an average value of two or more position detection values ​​detected by a plurality of mold buffer position detectors corresponding to a plurality of the first drive shafts.

[0031] In a control method of a die cushion device according to still another aspect of the present invention, in the specific die cushion load control step, the die cushion position controller controls the second drive shaft so as to be within ±2 mm with respect to the target value.

[0032] In another embodiment of the control method of the mold buffer device of the present invention, it is characterized in that the specific mold buffer load control process includes a mold buffer load control process when the mold is configured at an offset position relative to the center of the buffer pad, or a mold buffer load control process when there is no material on a part of the multiple drive shafts.

[0033] Effects of the Invention

[0034] According to the present invention, regardless of the arrangement of the mold, control can be performed in the mold cushion load control step so that the cushion pad does not tilt, and there is no restriction on the arrangement of the mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a diagram showing a structural example of a press machine to which the present invention is applied.

[0036] Figure 2 It is a figure which shows the whole structure of the die cushion device of this invention.

[0037] Figure 3 The diagram shows the relationship between the positions of the four driving points LF, LB, RF, and RB of the cushion pad 210 and the positions of the left and right dies 120L and 120R.

[0038] Figure 4 The diagram shows the positions of the dies, the driving points for performing the die cushion load control or the die cushion position control, and the like when performing normal die cushion load control and specific die cushion load control.

[0039] Figure 5 The diagrams show variations of the positions of the dies, the driving points for performing the die cushion load control or the die cushion position control, and the like when performing normal die cushion load control and when performing specific die cushion load control.

[0040] Figure 6 This is a diagram showing another variation of the position of the die, the driving point for performing the die cushion load control or the die cushion position control, and the like when a specific die cushion load control is performed.

[0041] Figure 7 It is shown Figure 2A block diagram of an embodiment of a die cushion control device in a die cushion device is shown.

[0042] Figure 8 : is a waveform diagram showing the slide position and the left front position of the die cushion when only the left component is produced.

[0043] Fig. 9 : is a waveform diagram showing the die cushion left front position, the die cushion right front position, the die cushion left rear position, and the die cushion right rear position when only the left component is produced.

[0044] Fig.10 It is a waveform diagram showing the deviation (die cushion left front position - die cushion right front position) between the die cushion left front position and the die cushion right front position when only the left component is produced.

[0045] Fig.11 It is a waveform diagram showing the loads on the left front, right front, left rear, and right rear drive shafts when only the left component is produced.

[0046] Fig.12 This is a waveform diagram showing a torque command signal of a representative one of three servomotors that respectively drive each drive shaft when only the left component is produced.

[0047] Fig.13 Will Fig. 9 The circle in the figure indicates an enlarged view of the X part.

[0048] Fig.14 Will Fig. 9 The circle in the figure shows an enlarged view of the Y part.

[0049] Fig.15 This is a flowchart showing an embodiment of a control method of a die cushion device according to the present invention.

[0050] Fig.16 It is a diagram for explaining the problems of the conventional die cushion device.

[0051] Description of reference numerals:

[0052] 10L, 10R... Materials;

[0053] 100...Stamping machinery;

[0054] 102...base;

[0055] 103... pad;

[0056] 104... Pillar;

[0057] 105...Connecting rod;

[0058] 108...Guidance Department;

[0059] 110...Sliding parts;

[0060] 112...Crankshaft;

[0061] 118...Encoder;

[0062] 120...Mold;

[0063] 120′...Mold;

[0064] 120L...Mold;

[0065] 120LD...lower die;

[0066] 120LU... Upper die;

[0067] 120R...Mold;

[0068] 120RD...lower die;

[0069] 120RU... Upper die;

[0070] 200...Mold buffer device;

[0071] 200mm...Mold buffer starts sliding position;

[0072] 202L, 202R...Blank holder;

[0073] 204...buffer pin;

[0074] 210, 210L, 210R... cushion;

[0075] 220LF, 220LB, 220RF, 220RB...Hydraulic cylinders;

[0076] 220LFa, 220LBa, 220RFa, 220RBa...piston rod;

[0077] 224...Mold buffer position detector;

[0078] 232...Piping;

[0079] 234...Piping;

[0080] 252...Liquid reservoir;

[0081] 253...Relief valve;

[0082] 258...Angular velocity detector;

[0083] 262...Check valve;

[0084] 264...Pressure detector;

[0085] 300LB... Left rear die buffer controller;

[0086] 300LF...Left front die buffer controller;

[0087] 300RB...Right rear die buffer controller;

[0088] 300RF...Right front mold buffer controller;

[0089] 302...Mold buffer position commander;

[0090] 304...Mold buffer position controller;

[0091] 306...Mold buffer load commander;

[0092] 308...Mold buffer load controller;

[0093] 310...Position command selector;

[0094] 320...Position controller;

[0095] 322, 331A~333A...Subtractor;

[0096] 324...Position control compensator;

[0097] 330... Stabilization Controller;

[0098] 331B~333B...stabilization control compensator;

[0099] 341, 342, 343... Adder;

[0100] 350...Feedforward compensator;

[0101] 352...differential elements;

[0102] 354...Phase advance compensation elements;

[0103] 356...adjuster;

[0104] 360...Torque command selector;

[0105] P / M1~P / M3...Hydraulic pump / motor;

[0106] SM1~SM3...Servo motor;

[0107] SWf1, SWf2, SWpr, SWtr... switches. DETAILED DESCRIPTION

[0108] Hereinafter, preferred embodiments of a die cushion device and a control method of a die cushion device according to the present invention will be described in detail with reference to the accompanying drawings.

[0109] [Stamping Machinery]

[0110] Figure 1 It is a diagram showing a configuration example of a press machine to which the present invention is applied.

[0111] exist Figure 1 In the illustrated press machine 100 , a frame is formed by a base 102 , columns 104 , and a beam (frame upper strength member) 106 , and a slide 110 is guided by a guide 108 provided on the column 104 so as to be movable in the up-down direction (vertical direction).

[0112] The slider 110 is connected to the crankshaft 112 via the connecting rod 105, and the rotational driving force is transmitted to the crankshaft 112 via a driving unit (equivalent to the part from the flywheel as a mechanical driving unit, from the servo motor as a servo driving unit to the speed reducer) not shown in the figure. The driving unit drives the crankshaft 112 to rotate, and the slider 110 is rotated. Figure 1 The upper edge moves in the up and down direction.

[0113] In addition, an encoder 118 for detecting the angle of the crankshaft 112 is provided on the crankshaft 112. The position signal of the slider 110 is converted (detected) based on the crankshaft angle signal detected by the encoder 118. In addition, the speed signal of the slider 110 can be detected by time differentiating the position signal of the slider 110.

[0114] In the present example, the slide 110 is equipped with two upper dies 120LU and 120RU, and the pad 103 on the base 102 is equipped with two lower dies 120LD and 120RD corresponding to the two upper dies 120LU and 120RU.

[0115] Blank holders (anti-wrinkle pressure plates) 202L and 202R are respectively arranged between the upper molds 120LU and 120RU and the lower molds 120LD and 120RD. The lower sides of the blank holders 202L and 202R are supported by buffer pads 210 via multiple buffer pins 204, and materials 10L and 10R are respectively placed on the upper sides of the blank holders 202L and 202R.

[0116] In the press machine 100, the material is press-formed between the upper die and the lower die by lowering the slide 110. The die cushion device 200 described later is a device that presses the periphery of the material to be press-formed from the bottom.

[0117] exist Figure 1The example shown shows the following situation: two upper molds 120LU and 120RU are assembled on the slide 110, and two lower molds 120LD and 120RD corresponding to the two upper molds 120LU and 120RU are assembled on the pad 103 on the base 102. After two products are produced at the same time, the two lower molds 120LD and 120RD are removed. Figure 1 The right mold 120R (upper mold 120RU, lower mold 120RD) is removed and only the left mold 120L (upper mold 120LU, lower mold 120LD) is assembled, and the material 10L is molded using only the left mold 120L.

[0118] [Mold cushion device]

[0119] Figure 1 This is a diagram showing the main mechanical parts of the die cushion device. Figure 2 It is a figure which shows the whole structure of the die cushion device of this invention.

[0120] exist Figure 1 In this example, the mold buffer device 200 has a buffer pad 210 that supports the blank holders 202L and 202R via the base 102 of the stamping machine 100 and a plurality of buffer pins 204 inserted into the pad 103, and a plurality of hydraulic cylinders (hydraulic cylinders) 220LF, 220LB, 220RF, and 220RB that have a plurality of drive shafts that support the buffer pad 210 and drive each drive shaft to lift and lower the buffer pad 210.

[0121] like Figure 2 As shown, the four hydraulic cylinders 220LF, 220LB, 220RF, and 220RB are respectively arranged at the left front, left rear, right front, and right rear relative to the buffer pad 210, and the piston rods 220LFa, 220LBa, 220RFFa, and 220RB of the hydraulic cylinders 220LF, 220LB, 220RF, and 220RB function as multiple driving shafts supporting the buffer pad 210.

[0122] like Figure 2 As shown, hydraulic devices for independently driving the four hydraulic cylinders 220LF, 220LB, 220RF, and 220RB are provided. The four hydraulic cylinders 220LF, 220LB, 220RF, and 220RB and the hydraulic devices function as a plurality of cushion lifting units for independently driving a plurality of drive shafts.

[0123] Here, the hydraulic devices that independently drive the hydraulic cylinders have the same structure. Figure 2 Only the hydraulic device of the right front hydraulic cylinder 220RF is shown in the figure, and the illustration of other hydraulic devices is omitted.

[0124] Therefore, the hydraulic device of the right front hydraulic cylinder 220RF will be described below.

[0125] As the hydraulic device of the hydraulic cylinder 220RF, a plurality of hydraulic pumps / motors (in this example, three hydraulic pumps / motors (P / M1 to P / M3)) are provided, and a plurality of servo motors (in this example, three servo motors (SM1 to SM3)) are connected to the rotating shafts of the respective hydraulic pumps / motors (P / M1 to P / M3). It should be noted that an angular velocity detector 258 is provided in each servo motor (SM1 to SM3), and each angular velocity detector 258 outputs an angular velocity signal indicating the rotational angular velocity of each servo motor (SM1 to SM3).

[0126] The ports of one side of the three hydraulic pumps / motors (P / M1 to P / M3) are connected to the pressurization chamber on one side of the hydraulic cylinder 220RF, i.e., the pressurization chamber on the mold buffer load generating side (rising side hydraulic chamber) through the piping 232, and the ports of the other side of the three hydraulic pumps / motors (P / M1 to P / M3) are connected to the hydraulic chamber on the other side of the hydraulic cylinder 220RF (rod side hydraulic chamber) through the piping 234 and are connected to the reservoir 252 that maintains a substantially constant low pressure.

[0127] In addition, Figure 2 In the embodiment, the hydraulic cylinder 220RF is provided with a mold cushion position detector 224 that detects the position of the cushion pad 210 in the lifting direction corresponding to the piston rod (drive shaft) and outputs a position detection value indicating the detected position. It should be noted that the mold cushion position detector 224 is not limited to detecting the position of the piston rod (drive shaft) of the hydraulic cylinder, and can also detect the position of the cushion pad 210 near each drive shaft.

[0128] The pipe 232 communicating with the hydraulic chamber on the lifting side of the hydraulic cylinder 220RF is provided with a pressure detector 264 that detects the pressure in the hydraulic chamber on the lifting side of the hydraulic cylinder 220RF and outputs a pressure signal corresponding to the die cushion load signal.

[0129] The accumulator 252 is provided with low-pressure air pressure to function as a tank, and also functions to supply substantially constant low-pressure oil to the hydraulic chamber on the rising side of the hydraulic cylinder 220RF via the check valve 262 to facilitate pressure increase during die cushion load control. In addition, the relief valve 253 provided in the hydraulic device functions as a unit that operates when abnormal pressure is generated (when die cushion load control cannot be performed and sudden abnormal pressure is generated) to prevent damage to the hydraulic device.

[0130] [Principle of die cushion load control]

[0131] The die cushion load acting on each drive shaft can be expressed by the product of the pressure of the hydraulic chamber on the ascending side of the hydraulic cylinder and the cylinder area. Therefore, controlling the die cushion load means controlling the pressure of the hydraulic chamber on the ascending side of the hydraulic cylinder.

[0132] Now, set it as follows:

[0133] Cross-sectional area of ​​the hydraulic chamber on the rising side of the hydraulic cylinder: a

[0134] Volume of the hydraulic chamber on the rising side of the hydraulic cylinder: V

[0135] Die cushion pressure: P

[0136] Servo motor torque: T

[0137] Servo motor inertia moment: I

[0138] Viscous drag coefficient of servo motor: DM

[0139] Friction torque of servo motor: fM

[0140] Displacement of hydraulic motor: Q

[0141] Force applied from the slide to the piston rod of the hydraulic cylinder: F slide

[0142] The speed of the cushion that is pressed during the punching process: v

[0143] Inertial mass of the hydraulic cylinder's piston rod + buffer pad: M

[0144] Viscous drag coefficient of hydraulic cylinder: DS

[0145] Friction force of hydraulic cylinder: fS

[0146] Angular velocity of the servo motor that rotates when pressed by the hydraulic oil: ω

[0147] Volume elastic coefficient of working oil: K

[0148] Proportional constants: k1, k2

[0149] The static behavior can be expressed by [Equation 1] and [Equation 2].

[0150] [Formula 1]

[0151] P=∫K((v·A-3k1Q·ω) / V)dt

[0152] [Formula 2]

[0153] T=k2·PQ / (2π)

[0154] In addition, the dynamic behavior can be expressed by [Formula 3] and [Formula 4] in addition to [Formula 1] and [Formula 2].

[0155] [Formula 3]

[0156] PA-F=M·dv / dt+DS·v+fS

[0157] [Formula 4]

[0158] T-k2·PQ / (2π)=I·dω / dt+DM·ω+fM

[0159] The object referred to by the above [Formula 1] to [Formula 4], i.e., the force transmitted from the slider 110 to the driving shaft of the hydraulic cylinder via the cushion 210, compresses the hydraulic chamber on the rising side of the hydraulic cylinder, thereby generating a mold cushion pressure. At the same time, the mold cushion pressure causes the hydraulic pump / motor (P / M1 to P / M3) to function as a hydraulic motor, and the rotating shaft torque generated in the hydraulic pump / motor (P / M1 to P / M3) overcomes the driving torque of the servo motor (SM1 to SM3), causing the servo motor (SM1 to SM3) to rotate, thereby suppressing the increase in pressure. As a result, the mold cushion pressure (mold cushion load) is determined according to the driving torque of the servo motor (SM1 to SM3).

[0160] Figure 2 The die cushion control device of the die cushion device 200 shown is composed of a die cushion position commander 302 , a die cushion position controller 304 , a die cushion load commander 306 , a die cushion load controller 308 , and a torque command selector 360 .

[0161] The mold buffer control device determines whether the slide 110 is located in a non-processing area or a processing area based on a position signal of the slide 110 calculated based on a crankshaft angle signal detected by the encoder 118, and switches to a mold buffer position control state performed by a mold buffer position controller 304 when the slide 110 is located in a non-processing area; and switches to a mold buffer load control state performed by a mold buffer load controller 308 when the slide 110 is located in a processing area.

[0162] The mold cushion position controller 304 generates a position control command signal (torque command signal) for driving each servomotor based on the mold cushion position command signal output from the mold cushion position commander 302 and the position signal (position detection value) of the cushion pad of each driving axis detected by the mold cushion position detector 224, and outputs the generated torque command signal to each servomotor (SM1 to SM3) via the torque command selector 360 and the amplifier, thereby controlling the position corresponding to each driving axis of the cushion pad 210. It should be noted that the mold cushion position controller 304 inputs an angular velocity signal group indicating the angular velocity (servo motor angular velocity (ω)) of each servomotor (SM1 to SM3) detected by the angular velocity detector 258, and uses the angular velocity signal group as an angular velocity feedback signal for ensuring the dynamic stability of the mold cushion position.

[0163] Preferably, in order to ensure dynamic stability, the speed of each servo motor ( SM1 to SM3 ) is controlled to thereby perform position control in the lifting direction of the cushion pad 210 .

[0164] In addition, in the case of a specific mold buffer load control process described later, the mold buffer position controller 304 generates a torque command signal corresponding to the second drive shaft in order to perform position control on a drive shaft (second drive shaft) selected as the drive shaft for mold buffer position control from among multiple drive shafts (in this example, four drive shafts: left front, left rear, right front, and right rear).

[0165] The die cushion load controller 308 generates a pressure control command signal (torque command signal) for driving each servomotor based on the die cushion load command signal for each drive shaft applied from the die cushion load commander 306 and the pressure signal indicating the pressure of the hydraulic chamber on the ascending side of each hydraulic cylinder detected by the pressure detector 264, and outputs the generated torque command signal to each servomotor (SM1 to SM3) via the torque command selector 360 and the amplifier, thereby controlling the die cushion load applied to each drive shaft of the cushion pad 210. It should be noted that the die cushion load controller 308 outputs an angular velocity signal group of each servomotor (SM1 to SM3) detected by the angular velocity detector 258, and uses the angular velocity signal group as an angular velocity feedback signal for ensuring the dynamic stability of the die cushion load.

[0166] In addition, in the case of a specific die cushion load control process, the die cushion load controller 308 performs the die cushion load control only on the drive axis (first drive axis) selected as the drive axis to be subjected to the die cushion load control among the plurality of drive axes in the die cushion load control process.

[0167] The torque command selector 360 basically selects the torque command signal generated by the mold buffer position controller 304 when the slide 110 is located in the non-processing area, and selects the torque command signal generated by the mold buffer load controller 308 when the slide 110 is located in the processing area, and outputs the selected torque command signal to the amplifier of the subsequent stage.

[0168] In addition, in the case of a specific mold buffer load control process, the torque command selector 360 does not select the torque command signals used to perform mold buffer load control on multiple drive axes respectively, but only selects and outputs the torque command signal generated for the first drive axis selected as the drive axis for mold buffer load control among the multiple drive axes, and selects and outputs the torque command signal generated by the mold buffer position controller 304 for the second drive axis selected as the drive axis for mold buffer position control among the multiple drive axes.

[0169] [Application example of specific die cushion load control]

[0170] Nowadays, in an automated production line of a stamping machine for producing a body of a motor vehicle, a stamping machine 100 and a die buffer device 200 ( Figure 1 , Figure 2 ) to produce parts for a certain part of the body of a certain car model (No.5).

[0171] Figure 3 The diagram shows the relationship between the positions of the four driving points LF, LB, RF, and RB of the cushion pad 210 and the positions of the left and right dies 120L and 120R.

[0172] like Figure 3 As shown, the parts of the vehicle body are composed of two parts, the front part (No. 5L) and the back part (No. 5R). The mold 120L for the front part is assembled on the left side of the stamping machine 100, and the mold 120R for the back part is assembled on the right side of the stamping machine 100, so that the two parts are produced at the same time.

[0173] The cushion pad 210 is a 4-point drive type, and the mold cushion load is set to 1000 kN for each axis (in other words, the left mold cushion load is 2000 kN, the right mold cushion load is 2000 kN, and the total mold cushion load is 4000 kN). The mold cushion stroke is 200 mm.

[0174] The drive shafts that independently drive the four drive points LF, LB, RF, and RB are the piston rods of hydraulic cylinders 220LF, 220LB, 220RF, and 220RB driven by hydraulic pumps / motors (P / M1 to P / M3) connected to the shafts of three servomotors (SM1 to SM3). In addition, the plate thickness of the material is 1.2 mm on the left and 1.6 mm on the right.

[0175] And after the production met the specified quantity (for example, 5,000 pieces) and was completed, trouble arose. In the post-process of the stamping line, during the quality inspection of the product, which was carried out almost simultaneously with the production (slightly delayed), damage (defective) was found on part of the surface of multiple (for example, 45) of the surface parts (L). All the inner parts (R) were normal.

[0176] At this time, before starting production of other parts by the next mold, in order to make up for the 45 unqualified watch parts (L), 45 additional watch parts (L) must be produced as soon as possible (condition X). In this condition X, when the left and right parts are produced simultaneously (two of them) by the left and right molds 120L and 120R, it is not possible to produce only the left parts, and the redundant right parts must also be produced simultaneously (condition Y).

[0177] This is because, if no material is placed on the right side and it is left vacant, the buffer pad 210 will tilt (tilt in a manner that sinks to the left side) by an amount corresponding to the thickness of the material (taking into account the thickness after forming), resulting in defectiveness in the production of the left part, damage to the machinery (for example, the drive shafts that drive the buffer pad 210), etc., causing a malfunction.

[0178] <Overview of the Invention>

[0179] In the present invention, specific die buffer load control is performed. For example, in condition X, even in a stamping machine that produces left and right parts at the same time (take two), only the left die 120L continues to be used, and only the left part can be produced well without producing excess right parts at the same time (condition Z).

[0180] Figure 4 The diagram shows the positions of the dies, the driving points for performing the die cushion load control or the die cushion position control, and the like when performing normal die cushion load control and specific die cushion load control.

[0181] Figure 4 (A) indicates the normal production situation where the left and right parts are produced at the same time. Figure 4 (B) shows the case where only the left component is produced. Figure 4In the figure, the reference numeral A in a circle indicates a driving point for performing die cushion load control, and the reference numeral B indicates a driving point for performing die cushion position control.

[0182] exist Figure 4 In the case of normal production represented by (A), in the die cushion load step, all four driving points LF, LB, RF, and RB for the cushion pad 210 are set as the driving point A for performing the die cushion load control.

[0183] On the other hand, Figure 4 In the case of condition Z represented by (B), in the mold buffer load control process, the driving points LF and LB corresponding to the mold 120L on the left among the four driving points LF, LB, RF, and RB are set as driving points A for mold buffer load control, and the driving points RF and RB corresponding to the mold 120R on the right are set as driving points B for mold buffer position control.

[0184] That is, in Figure 4 In the case of condition Z represented by (B), in the die buffer load control process, a specific die buffer load control is implemented in which the die buffer load control is performed only on the driving shaft (first driving shaft) selected as the driving shaft for die buffer load control among the multiple driving shafts of the driving buffer pad.

[0185] In a specific die buffer load control, die buffer position control is performed in a die buffer load control process for a drive shaft (second drive shaft) other than the first drive shaft among the plurality of drive shafts. In addition, in the die buffer position control in this case, the die buffer (cushion pad) position of the first drive shaft adjacent to the second drive shaft for which the die buffer position control is performed is controlled to a target value in position control.

[0186] In the case of situation Z, if the operator presses a "produce left side only" button on the die cushion operation screen (not shown), specific die cushion load control is implemented, and only the left die 120L is used to produce only the left component.

[0187] Therefore, even if no material is placed on the right side (and even if no mold is assembled on the right side), during forming, a force is always applied to the driving axes corresponding to the two driving points RF and RB on the right side to keep the buffer pad 210 parallel, so that only the left part is produced well and the machine (for example, the driving axes that drive the buffer pad 210) will not be damaged.

[0188] Figure 5 The diagrams show variations A to H of the positions of the dies, the driving points for performing the die cushion load control or the die cushion position control, etc., when normal die cushion load control and specific die cushion load control are performed.

[0189] Variations A, B, and E respectively show the positions of the dies (120, 120L, 120R, 120', 120LF, and 120RB) relative to the cushion pad 210 when the normal die cushion load control is performed. In the case of these die positions, the four driving points are driving points A where the die cushion load control is performed in all the die cushion load control steps.

[0190] On the other hand, Modifications C, D, F, G, and H respectively show the position of the mold (120R, 120LF, 120RF, and 120RB) relative to the cushion pad 210 when performing specific mold cushion load control. The specific mold cushion load control process includes a mold cushion load control process in which the mold is arranged at a position offset from the center of the cushion pad 210, or a mold cushion load control process in which a material does not exist on a part of the plurality of drive shafts.

[0191] Variant G is equivalent to Figure 4 The force shown in (B) shows the position of the mold 120L when only the left part is produced, and the left driving point is set to the driving point A corresponding to the first driving axis that performs mold buffer load control in the mold buffer load control process, and the right driving point is set to the driving point B corresponding to the second driving axis that performs mold buffer position control in the mold buffer load control process in a manner that makes the mold buffer positions of the respective adjacent left driving points A become target values ​​in position control.

[0192] Variant C shows the position of the mold 120R when only the right part is produced, which is opposite to Variant G. The right driving point is set to the driving point A corresponding to the first driving axis that performs mold buffer load control in the mold buffer load control process, and the left driving point is set to the driving point B corresponding to the second driving axis that performs mold buffer position control in the mold buffer load control process in a manner that makes the mold buffer positions of the respective adjacent right driving points A become target values ​​in position control.

[0193] Variants D, F, and H each have a driving point within the projection surface of the mold (120LF, 120RF, 120RB), and the driving point is set to a driving point A corresponding to the first driving axis that performs mold buffer load control in the mold buffer load control process, and the other driving points are set to driving points B of the second driving axis that performs mold buffer position control in the mold buffer load control process in such a manner that the mold buffer position of the adjacent driving point A becomes the target value in the position control.

[0194] Figure 61 is a diagram showing another variation IJ of the position of the die, the driving point for performing the die cushion load control and the die cushion position control, etc., when a specific die cushion load control is performed.

[0195] exist Figure 6 In the variation IJ shown, there are cushion pads 210L and 210R divided into two parts, each cushion pad 210L and 210R is applied to a mold cushion device driven by four drive shafts, and molds 120 and 120' are arranged at positions straddling the left and right cushion pads 210L and 210R.

[0196] In variant I, there are four driving points on the inner side of the projection surface of the mold 120, and these driving points are set as driving points A corresponding to the first driving axis that performs mold buffer load control in the mold buffer load control process, and the driving points on the outer side of the projection surface of the mold 120 are set as driving points B of the second driving axis that performs mold buffer position control in the mold buffer load control process in a manner that makes the mold buffer position of the adjacent driving point A become the target value in position control.

[0197] In variant J, the right front driving point of the left side buffer pad 210L close to the mold 120' and the left front driving point of the right side buffer pad 210R are set as driving point A corresponding to the first driving axis that performs mold buffer load control in the mold buffer load control process, and the other driving points are set as driving point B of the second driving axis that performs mold buffer position control in the mold buffer load control process in a manner that makes the mold buffer position of the adjacent driving point A become the target value in position control.

[0198] [Mold cushion control device]

[0199] Figure 7 Yes means Figure 2 The block diagram of the embodiment of the die cushion control device in the die cushion device 200 shown in FIG. The die cushion load control in the die cushion control device is described with respect to the case where a specific die cushion load control is performed for the case where only the left component is produced by the die 120L for the condition X.

[0200] like Figure 7 As shown, the mold buffer control device is composed of a mold buffer position commander 302, a mold buffer load commander 306, and four mold buffer controllers (left front mold buffer controller 300LF, right front mold buffer controller 300RF, left rear mold buffer controller 300LB, right rear mold buffer controller 300RB) corresponding to the four driving shafts of the left front, left rear, right front, and right rear, respectively.

[0201] The four die buffer controllers have the same structure. Figure 7 , only the right front mold buffer controller 300RF is shown in detail.

[0202] The right front die cushion controller 300RF is composed of a die cushion position controller 304 , a die cushion load controller 308 , and a torque command selector 360 .

[0203] When the mold cushion position commander 302 determines that the slide 110 is located in a non-machining process area based on the slide 110 position signal calculated based on the crankshaft angle signal detected by the encoder 118 , it outputs a position command value of the cushion pad 210 based on the slide 110 position signal.

[0204] In this example, the mold buffer position commander 302 outputs a position command value indicating the buffer pad standby position during position control in which the buffer pad 210 is placed on standby at a preset buffer pad standby position, outputs a position command value for pre-accelerating the buffer pad 210 when the buffer pad 210 is pre-accelerated from the buffer pad standby position in order to reduce the impact (force) in a collision when the mold buffer load is applied, and when the slide 110 reaches the bottom dead point and the mold buffer load control is ended, the product is demolded and a position command value for resetting the buffer pad 210 to the mold buffer standby position is output.

[0205] The die cushion position controller 304 is composed of a position command selector 310 , a position controller 320 , a stabilization controller 330 , a feedforward compensator 350 , and adders 341 - 343 .

[0206] The position command selector 310 selects either one of the position command value from the die cushion position controller 304 applied to the input A and the position signal (position detection value) of the cushion pad 210 at the driving point LF of the left front driving shaft detected by the die cushion position detector 224 applied to the input B. Here, the position detection value applied to the input B is the driving point at which the die cushion load control is performed in a specific die cushion load control process and the position detection value at the left front driving point LF adjacent to the driving point RF of the right front die cushion controller 300RF.

[0207] In the case of a situation other than the mold buffer load process and when the right front drive shaft is selected as the first drive shaft for mold buffer load control in the mold buffer load process, the position command selector 310 switches the switch SWpr to input A and selects the position command value input from the mold buffer position controller 304. In the case of a situation other than the mold buffer load process and when the right front drive shaft is selected as the second drive shaft for mold buffer position control in the mold buffer load process, the switch SWpr is switched to input B and the position detection value of the left front drive shaft is selected as the target value (position command value) of the mold buffer position control.

[0208] In this example, it is assumed that only the left component is produced by the mold 120L for condition X, so the position command selector 310 selects the right front drive shaft as the second drive shaft for mold buffer position control in the mold buffer loading process, and selects the position detection value of the left front drive shaft as the position command value and outputs it.

[0209] The position controller 320 includes a subtractor 322 and a position control compensator 324. The position command value selected by the position command selector 310 is added to the positive input of the subtractor 322, and the position detection value of the right front driving point RF of the cushion pad 210 detected by the right front mold cushion position detector 224 is added to the negative input. The subtractor 322 calculates the deviation (position deviation) of the position detection value relative to the position command value, and outputs it to the position control compensator 324 in order to reduce the calculated position deviation.

[0210] The position control compensator 324 calculates a signal contributing to reduction of the position deviation by adding a compensation amount proportional to the position deviation to a compensation amount proportional to the integrated amount of the position deviation, and so on.

[0211] The stabilization controller 330 has three subtractors (331A~333A) and three stabilization control compensators (331B~333B), and the position controller 320 independently plays the role of solving the problem of the phase delay of an open-loop transfer function (open loop) of the mold buffer position control system from the position command value to the position detection value becoming larger and the position control function becoming unstable.

[0212] A signal calculated by the position controller 320 is added to the positive input of each subtractor (331A~333A), and an angular velocity signal (FR1~FR3) indicating the angular velocity of each servo motor (SM1~SM3) detected by the angular velocity detector 258 is added to the negative input as an angular velocity feedback signal. Each subtractor (331A~333A) calculates the deviation (angular velocity deviation) of the two input signals and outputs the calculated angular velocity deviation to the stabilization control compensator (331B~333B).

[0213] Each stabilization control compensator (331B to 333B) calculates a signal that helps reduce the angular velocity deviation by performing operations such as adding a compensation amount proportional to the angular velocity deviation calculated by each subtractor (331A to 333A) to a compensation amount proportional to the integrated amount of the angular velocity deviation.

[0214] The signals calculated by the stabilization control compensators (331B to 333B) are output to the adders (341 to 343) as torque command signals for the servo motors (SM1 to SM3).

[0215] The feedforward compensator 350 includes a differential element 352, a phase advance compensation element 354, an adjuster 356, and switches SWf1 and SWf2, and functions to reduce the deviation between the position command value and the position detection value in the position control of the cushion pad 210. In particular, the right front feedforward compensator 350 turns on the switch SWf1 when the right front drive shaft is selected as the second drive shaft for performing the position control of the cushion pad in the cushion pad loading process, and functions to perform the feedforward compensation.

[0216] The differential element 352 of the feedforward compensator 350 outputs a structure obtained by time-differentiating the position command value when the position detection value (position command value) of the input B is selected by the position command selector 310. Here, the transfer function of the differential element 352 is not simply set to S (S is the Laplace operator), but is set to ωaS / (S+ωa). The reason for multiplying the differential by the low-pass filter of the angular frequency ωa is to smoothly process the time differential operation within a limited operation cycle in the digital (discrete value) operation.

[0217] It should be noted that the differential signal of the mold buffer position (= mold buffer position instruction) signal of the left front and left rear drive shafts in the mold buffer load control process is almost the same as the slide speed signal in the mold buffer load control process, so the differential signal of the mold buffer position signal can also be used instead of the slide speed signal.

[0218] When the upper die 120LU on the left collides with the buffer pad 210 via the material 10L, the lower die 120LD-blank holder 202, and the buffer pin 204, the upper die 120LU contacts the main body of the lower die 120LD near the lower dead center and the stamping frame begins to extend, the forming of the left part is completed, and the mold buffer load on the left is removed, and when the position detection value of the left front drive shaft and the position detection value of the left rear drive shaft, which function as the position command value of the right front drive shaft, change sharply, specific high-frequency components are respectively included in the mold buffer position signal, but the phase compensation element functioning in the feedforward compensator 350 plays a role in compensating in a manner that makes the position deviation relative to the specific high-frequency component extremely small.

[0219] The phase advance compensation element 354 is a compensation element that advances the phase of the input signal, and its transfer function is represented by (1+T2·S) / (1+T1·s). T1 and T2 (where T1<T2) are constants, and are preferably appropriately set according to a specific high frequency component.

[0220] The phase advance compensation element 354 is characterized in that it is not arranged in series with the compensation elements constituting a closed loop such as the position controller 320 and the stabilization controller 330, but is arranged in series with the feedforward compensator 350 constituting an open loop. In this way, the position control system itself does not increase noise and does not become unstable.

[0221] The switch SWf2 selects the input x to which the output signal of the differential element 352 is added, or the input y to which the output signal of the differential element 352 and the output signal of the phase advance compensation element 354 are added, and outputs the selected signal to the subsequent regulator 356. It should be noted that the switch SWf2 is switched to the input y during a constant period at the start and end of the die cushion loading process, and is switched to the input x during other periods, but details of the switching timing of the switch SWf2 will be described later.

[0222] The regulator 356 adjusts the gain of the signal input via the switch SWf2. The differential element 352 and the regulator 356 compensate for the phase delay of the servo motor angular velocity signal (obviously equivalent to the speed command signal of the servo motor) relative to the output signal from the position control compensator 324, which is the cost (side effect) of stabilization by the stabilization controller 330.

[0223] The switch SWf1 is turned on in the die cushion load process when the right front drive shaft is selected as the second drive shaft for performing die cushion position control as described above, and functions as the right front feedforward compensator 350. The output signals from the feedforward compensator 350 outputted via the switch SWf1 are outputted to the adders (341 to 343).

[0224] In the other inputs of adders 341 to 343, signals calculated by each stabilization control compensator (331B to 333B) of the stabilization controller 330 are added as torque command signals for each servo motor (SM1 to SM3). When the feedforward compensator 350 is functioning (i.e., the switch SWf1 is set to ON), adders 341 to 343 add the torque command signals for each servo motor (SM1 to SM3) to the output signal from the feedforward compensator 350, and output the addition result to the torque command selector 360. When the feedforward compensator 350 is not functioning (i.e., the switch SWf1 is set to OFF), the torque command signals for each servo motor (SM1 to SM3) calculated by each stabilization control compensator (331B to 333B) are output to the torque command selector 360 as is.

[0225] A torque command signal for each servo motor ( SM1 to SM3 ) generated by the die cushion load controller 308 is added to the other input F of the torque command selector 360 .

[0226] The torque command selector 360 basically selects the torque command signal generated by the mold buffer position controller 304 when the slide 110 is located in the non-processing area, and selects the torque command signal generated by the mold buffer load controller 308 when the slide 110 is located in the processing area. The torque command selector 360 outputs the selected torque command signal (RF1~RF3) to each servo motor (SM1~SM3) via the amplifier.

[0227] The torque command selector 360 also functions as a selector for selecting whether the right front drive axis of the cushion pad 210 is set as the first drive axis for performing the die cushion load control by the die cushion load controller 308 or the second drive axis for performing the die cushion position control by the die cushion position controller 304 .

[0228] That is, the torque command selector 360 of the right front mold buffer controller 300RF for the right front drive shaft that implements a specific mold buffer load control process also selects the torque command signal on the input P side generated by the mold buffer position controller 304 during the mold buffer load control process, thereby selecting the right front drive shaft as the second drive shaft for performing mold buffer position control.

[0229] On the other hand, the die cushion load controller 308 of each driving axis has no direct relationship with the gist of the present invention, and thus will be briefly described below.

[0230] In the mold buffer load controller 308 of the right front mold buffer controller 300RF, the mold buffer load instruction signal from the mold buffer load commander 306 is added to the pressure signal from the pressure detector 264 that detects the pressure of the rising side hydraulic chamber of the right front hydraulic cylinder 220RF corresponding to the right front drive shaft.

[0231] The mold buffer load controller 308 generates a pressure control command signal (torque command signal) for driving the three servo motors (SM1 to SM3) corresponding to the right front hydraulic cylinder 220RF based on the input mold buffer load command signal and pressure signal, and outputs the generated torque command signal to the torque command selector 360.

[0232] The mold buffer load controller 308 is provided with a stabilization controller (not shown) similarly to the stabilization controller 330 of the mold buffer position controller 304, and uses angular velocity signals (FR1 to FR3) representing the angular velocity of each servo motor (SM1 to SM3) in generating torque command signals for driving each servo motor (SM1 to SM3) respectively.

[0233] It should be noted that the mold buffer load controller 308 of the right front mold buffer controller 300RF generates a torque command signal for causing the right front hydraulic cylinder 220RF to generate a mold buffer load. However, in this example, the right front hydraulic cylinder 220RF performs mold buffer position control in the mold buffer load process (the torque command selector 360 selects the torque command signal from the mold buffer position controller 304), so the generation of the torque command signal by the mold buffer load controller 308 can also be stopped.

[0234] In the case of this example, the right rear die cushion controller 300RB, like the right front die cushion controller 300RF, performs position control on the right rear hydraulic cylinder 220RB in accordance with the torque instruction signal from the die cushion position controller 304 in the die cushion loading process.

[0235] On the other hand, the left front die cushion controller 300LF and the left rear die cushion controller 300LB each perform normal die cushion load control based on the torque instruction signal from the die cushion load controller 308 in the die cushion load process.

[0236] [Function of mold cushion device]

[0237] Next, refer to Figures 8 to 12 The function of the die cushion device 200 is described. It should be noted that: Figures 8 to 12This is a diagram showing main physical quantities in the molding (mold cushion load control) process and the product demolding process in relation to the elapsed time when only the left component is produced (case Z).

[0238] Figure 8 This is a waveform diagram showing the slide position and the left front position of the die cushion when only the left part is produced. The left front position of the die cushion indicates the position of the cushion pad corresponding to the left front driving point driven by the left front driving shaft.

[0239] Fig. 9 It is a waveform graph showing the die cushion left front position, the die cushion right front position, the die cushion left rear position, and the die cushion right rear position when only the left component is produced.

[0240] These positions are basically position-controlled in order to follow the common mold buffer position command signal such as the mold buffer start position command and the mold release position command obtained by integrating the mold release speed setting during mold release throughout the entire cycle. However, in the mold buffer load control process, the mold buffer right front position and the mold buffer right rear position use the mold buffer left front position and the mold buffer left rear position as position command values, respectively, and are position-controlled in such a way that the position deviation relative to them becomes (as much as possible) 0.

[0241] It should be noted that in Fig. 9 The above four positions are roughly consistent, and the buffer pad 210 is kept horizontal.

[0242] Fig.10 This is a waveform diagram showing the deviation between the die cushion left front position and the die cushion right front position (die cushion left front position - die cushion right front position) when only the left component is produced. The absolute value of this deviation is limited to about 1 mm at most.

[0243] Fig.11 : is a waveform diagram showing the load of each drive shaft (left front, right front, left rear, right rear) when only the left component is produced.

[0244] like Fig.11 As shown, the loads of the left front and left rear drive shafts are roughly the same, and the loads of the right front and right rear drive shafts are roughly the same.

[0245] In addition, the load means the die cushion load in the die cushion load acting process with respect to the drive shaft (in this case, the left front drive shaft and the left rear drive shaft) that controls the die cushion load.

[0246] Fig.12 This is a waveform diagram showing a torque command signal of a representative one of three servomotors that respectively drive each drive shaft when only the left component is produced.

[0247] like Fig.12 As shown, the torque command signals of the servo motors driving the left front and left rear drive shafts are substantially consistent, and the torque command signals of the servo motors driving the right front and right rear drive shafts are substantially consistent.

[0248] Fig.13 as well as Fig.14 They are Fig. 9 The circles in the figure show enlarged views of the X and Y parts.

[0249] <Cushion pad standby process>

[0250] exist Figure 8 At about 2.3 seconds as shown, the cushion pad holds the left and right blank holders at the sliding position of 200 mm at the start of die cushioning via the cushion pins. The left blank holder is loaded with material, and the right blank holder is not loaded with material.

[0251] At this time, Figure 7 In the die cushion control device shown, the switch SWtr of the torque command selector 360 of each drive axis selects the torque command signal for position control input to the P side, and the die cushion position controller 304 functions.

[0252] In the die cushion position controller 304 of each drive axis, the switch SWpr of the position command selector 310 is switched to the input A side, and the die cushion start position (standby position) command signal output from the die cushion position commander 302 is selected as the die cushion position command value.

[0253] In the feedforward compensator 350 , the switch SWf1 is turned OFF, and the feedforward compensation does not function.

[0254] The torque command signal for position control generated by the die cushion position controller 304 of each drive axis is output as a torque command signal (LF1 to LF3, LB1 to LB3, RF1 to RF3, RB1 to RB3) to the three servo motors (SM1 to SM3) that drive each drive axis respectively via the torque command selector 360. Thus, each drive axis is position-controlled in such a manner that the cushion pad 210 stands by at a predetermined cushion pad standby position.

[0255] In the cushion standby process (around 2.3 seconds) performed by the mold cushion position control, for example Fig.10 As shown in FIG. 1 , the left and right position deviation of the mold buffer front side is almost 0. In addition, as shown in FIG. Fig.12 As shown, the torque signals of the representative servo motors driving the drive shafts are also synchronized.

[0256] <Pre-acceleration process before forming>

[0257] like Fig.13 As shown, at around 2.55 seconds, the cushion is slightly accelerated downward in order to mitigate the impact when the left upper die 120LU collides with the lower die 120LD-blank holder 202L via the material 10L at the start of forming.

[0258] At this time, Figure 7 In the die cushion control device shown, the switch SWtr of the torque command selector 360 of each drive axis selects the torque command signal for position control input to the P side, and the die cushion position controller 304 functions.

[0259] In the die cushion position controller 304 of each driving axis, the switch SWpr of the position command selector 310 is switched to the input A side, and the pre-acceleration die cushion position command value output from the die cushion position commander 302 is selected as the die cushion position command value.

[0260] In the feedforward compensator 350 , the switch SWf1 is turned OFF, and the feedforward compensation does not function.

[0261] As a result, in the pre-acceleration process, the position controller 320 and the stabilization controller 330 of each servo motor function, and the die cushion positions of the respective drive axes are position-controlled and synchronized so as to follow the common pre-acceleration position command signal.

[0262] For example, in Fig.10 In the mold buffer, the left and right position deviation is about -0.03mm. Fig.12 In the figure, the torque command signals of the representative servo motors driving the drive shafts are also synchronized (while showing negative values).

[0263] <(Left) Forming (die cushion load control) process>

[0264] like Fig.11 As shown, the die cushion load acts on the left side of the cushion pad from 2.6 seconds to 3.41 seconds, so that the left part is formed. The operating force to maintain balance acts on the right side of the cushion pad by the die cushion position control so that the cushion pad does not tilt to the left or right.

[0265] At this time, Figure 7 In the mold buffer control device shown, each switch SWpr of the position command selector 310RF, 310RB of the right front drive shaft and the right rear drive shaft is switched to the input B side, and the position signal of the left front drive shaft and the position signal of the left rear drive shaft in the mold buffer load control which are indirectly pressed down by sliding are respectively used as buffer position command values ​​(target values ​​of position control).

[0266] In the feedforward compensator 350 , the switch SWf1 is turned on, and the feedforward compensation functions.

[0267] Regarding the feedforward compensator 350, when the upper die 120LU on the left collides with the cushion 210 via the material 10L, the lower die 120LD-the blank holder 202L, and the cushion pin 204, Fig. 9 X part ( Fig.13 ), the switch SWf2 in the feedforward compensator 350 is switched to the input y side within 0.03 seconds from the time point of 2.59 seconds, so that the time constants are T 1X , T 2X (where T 1X <T 2X )'s phase advance compensation element 354 comes into play.

[0268] This is in line with Fig.12 This is related to the effect that the torque of the right front and right rear of the middle servo motor changes greatly to the negative side, thereby strongly accelerating the left side of the cushion pad downward.

[0269] After that, the switch SWf2 is temporarily switched to the input x side and near the bottom dead center ( Fig. 9 Y part ( Fig.14 )) is switched to the input y side again, so that the time constants are respectively T and T in the period of about 0.02 seconds from before the main bodies of the upper and lower molds start to contact until the cushion load of the left mold is just removed. 1Y , T 2Y (where T 1Y <T 2Y )'s phase advance compensation element 354 comes into play.

[0270] As a result, in the forming process, the position controller 320, the stabilization controllers 330 of the servo motors, and the feedforward compensator 350 function, and the mold buffer positions of the right front and right rear drive shafts are position-controlled and synchronized in a manner that follows the mold buffer position (target value) of the first drive shaft that is subjected to mold buffer load control with less deviation.

[0271] In this way, in a specific mold buffer load control process, when calculating the torque command signal for the second drive shaft whose mold buffer position is controlled, the torque command signal of the servo motor corresponding to the second drive shaft is calculated based on the target value and the position detection value, and the calculated torque command signal is added to the feedforward compensation amount calculated by the feedforward compensator 350, so that the mold buffer position can be controlled in a manner within ±2 mm relative to the target value.

[0272] In this example, if Fig.10As shown, the position deviation is controlled within about -1.2 mm to 0 mm relative to the target value.

[0273] It should be noted that the reason for controlling the position within ±2 mm relative to the target value is that if the position exceeds ±2 mm, the allowable inclination angle of the cushion pad set in the die cushion device of this example is exceeded, and the die cushion device may stop abnormally.

[0274] In addition, in this example, the drive shafts (second drive shafts) that perform mold buffer position control in a specific mold buffer load process are the right front and right rear drive shafts. When mold buffer position control is performed on these drive shafts, the mold buffer (buffer pad) positions of the adjacent (closer) drive shafts among the left front and left rear drive shafts (first drive shafts) that perform mold buffer load control are set as target values ​​for position control, but this is not limited to this, and the average value of two or more position detection values ​​detected by each mold buffer position detector corresponding to more than one first drive shaft may also be used as a common target value.

[0275] <Mold release process>

[0276] exist Figure 8 After about 3.41 seconds, the cushion pad is loaded with the molded product and rises (performs a demolding operation) at a predetermined (predetermined) demolding speed until the mold cushion starts sliding at the position (standby position).

[0277] At this time, Figure 7 In the die cushion control device shown, the switch SWtr of the torque command selector 360 of each drive axis selects the torque command signal for position control input to the P side, so that the die cushion position controller 304 functions.

[0278] In the die cushion position controller 304 of each driving axis, the switch SWpr of the position command selector 310 is switched to the input A side, and the mold release position command signal output from the die cushion position commander 302 is selected as the die cushion position command value.

[0279] In the feedforward compensator 350 , the switch SWf1 is turned OFF, and the feedforward compensation does not function.

[0280] As a result, in the mold release process, the position controller 320 and the stabilization controller 330 of each servo motor function, and the mold cushion positions of the respective drive axes are position-controlled and synchronized so as to follow the common mold release position command signal.

[0281] It should be noted that in this example, an example of a controller that can freely arrange the mold only in the left and right direction is shown, but of course a controller that can freely arrange the mold in the front and back direction can also be adopted for the same considerations as this example.

[0282] <Control method of die cushion device>

[0283] Fig.15 This is a flowchart showing an embodiment of a control method of a die cushion device according to the present invention.

[0284] Fig.15 It is shown that in particular Figure 1 , Figure 2 The diagram of the control method of the die cushion device 200 shown here is shown with respect to the case where only the left component is produced by the left die 120L (the case of condition Z).

[0285] exist Fig.15 In the process, for each of the four driving axes of the left front, left rear, right front and right rear corresponding to the four hydraulic cylinders (220LF, 220LB, 220RF, 220RB) driving the buffer pad 210, it is selected whether to set it as the first driving axis for performing mold buffer load control based on the mold buffer load controller 308, or to set it as the second driving axis for performing mold buffer position control based on the mold buffer position controller 304 (step S10).

[0286] This selection can be made, for example, by pressing a button assigned with "Only left production" on the die cushion operation screen, and based on the selection result, the torque command signal in the torque command selector 360 of each drive axis and the position command selector 310 ( Figure 7 ) etc. In this example, the two drive shafts corresponding to the left hydraulic cylinders (220LF, 220LB) are selected as the first drive shafts, and the two drive shafts corresponding to the right hydraulic cylinders (220RF, 220RB) are selected as the second drive shafts.

[0287] Next, the die cushion position controller 304 of each driving axis controls the position of each driving axis so that the cushion pad 210 stands by at a predetermined cushion pad standby position (step S12 ).

[0288] During the cushion standby, the mold cushion control device determines whether the slide 110 has reached the pre-acceleration position based on the slide position signal indicating the position of the slide 110 (step S14). If the position of the slide 110 reaches the pre-acceleration position, the mold cushion position controller 304 of each drive axis controls the position of the cushion 210 based on the pre-acceleration mold cushion position command value (pre-accelerates the cushion 210) (step S16).

[0289] During the pre-acceleration, the die cushion control device determines whether the slide 110 has reached a position where it collides with the cushion pad 210 via the die 120L, the material, etc. based on the slide position signal indicating the position of the slide 110 (step S18). If the position of the slide 110 reaches a position where it collides with the cushion pad 210, the four die cushion controllers corresponding to each drive axis branch the control method in the die cushion loading process according to whether the drive axis of each control object is the first drive axis or the second drive axis (step S20).

[0290] In this example, the left front and left rear mold buffer controllers control the drive axes selected as the first drive axes through the mold buffer load controller 308 (step S22), and the right front and right rear mold buffer controllers control the drive axes selected as the second drive axes through the mold buffer position controller 304.

[0291] In the die buffer position control performed by the die buffer position controller 304 in this case, the position detection value detected by the die buffer position detector corresponding to the first drive shaft adjacent to the second drive shaft is used as a target value. In this example, the die buffer position controller 304 corresponding to the right front drive shaft uses the position detection value detected by the die buffer position detector corresponding to the left front drive shaft performing the die buffer load control as a target value, and the die buffer position controller 304 corresponding to the right rear drive shaft uses the position detection value detected by the die buffer position detector corresponding to the left rear drive shaft performing the die buffer load control as a target value.

[0292] Next, the mold cushion control device determines whether the mold cushion load control is completed (whether the slide 110 has reached the predetermined lower dead center vicinity area) (step S26). If the mold cushion load control is completed, the mold cushion position controller 304 of each drive axis controls the position of the cushion pad 210 based on the mold cushion position command value for demolding (step S28).

[0293] If the cushion pad 210 reaches the standby position, it is determined whether the press operation is terminated (step S32). If it is determined not to be terminated, the process proceeds to step S12 and the processes from step S12 to step S32 are repeated. If it is determined to be terminated, the production of the left component in the case of condition Z is terminated.

[0294] [other]

[0295] In the present embodiment, it is set that by pressing the "Left Side Production Only" button in the mold buffer operation screen, it is manually selected which of the four drive axes, the left front, left rear, right front, and right rear, is to be set as the first drive axis for mold buffer load control or the second drive axis for not performing mold buffer load control (the second drive axis for mold buffer position control) in a specific mold buffer load control process, and the selection in the torque command selector 360 and the position command selector 310 is performed according to the selection result, but it is not limited to this. The selection (identification) of the first drive axis or the second drive axis can also be automatically performed as follows: in the cushion standby (position control), the pressure of the hydraulic cylinder corresponding to each drive axis is compared and calculated to determine which drive axis bears the mass of the mold-blank holder; or, area sensors (a plurality of area sensors for detecting the state of being equipped with a mold) are installed at various locations on the pad, and the signals of these area sensors are compared and calculated to identify the area where the mold is installed.

[0296] In the present embodiment, a case where a hydraulic cylinder is used to lift the cushion pad and oil is used as the working fluid of the hydraulic pump / motor is described, but the present invention is not limited to this and water or other liquids may be used.

[0297] In addition, the cushion pad lifting unit that causes the cushion pad to perform lifting and lowering actions is composed of a hydraulic cylinder, a hydraulic pump / motor, and a servo motor, but is not limited to this. As long as the mold cushion load control and the mold cushion position control can be performed, for example, it can also be basically composed of a screw-nut mechanism that causes the cushion pad to be lifted and lowered, and a mechanism using a servo motor that drives the screw-nut mechanism, or it can also be basically composed of a rack-and-pinion mechanism that causes the cushion pad to be lifted and lowered, and a servo motor that drives the rack-and-pinion mechanism. Moreover, the present invention can also be applied to any device as long as it is a servo mold cushion device.

[0298] In addition, the number of drive shafts for one cushion pad in the mold cushion device is not limited to four in this example, and can be two or more, and the cushion pad can also be divided into multiple parts (for example, Figure 6 The division shown is two left and right).

[0299] In addition, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention.

Claims

1. A mold buffer device, characterized in that: The die buffer device comprises: A plurality of cushion lifting units, each having a plurality of drive shafts for supporting the cushion, and driving each drive shaft to lift the cushion; A mold buffer load controller, which controls the driving shafts of the plurality of buffer pad lifting units respectively so that the buffer pads generate a mold buffer load; a mold buffer position controller, which controls the driving shafts of the plurality of buffer pad lifting units respectively to control the position of the buffer pad; and a selector for independently selecting, for each of the driving shafts of the plurality of cushion lifting units, whether to be a first driving shaft for performing the die cushion load control based on the die cushion load controller or a second driving shaft for performing the die cushion position control based on the die cushion position controller instead of performing the die cushion load control based on the die cushion load controller, In a specific die cushion load control process, the die cushion load controller controls the first drive axis selected by the selector, and the die cushion position controller controls the second drive axis selected by the selector.

2. The mold buffer device according to claim 1, characterized in that: The die cushion device includes a plurality of die cushion position detectors, which detect positions of the cushion pads in the lifting direction corresponding to the positions of the driving shafts of the plurality of cushion pad lifting units and output position detection values ​​indicating the detected positions, respectively. In the specific die cushion load control step, the die cushion position controller controls the second drive shaft based on a position detection value detected by the die cushion position detector corresponding to the first drive shaft.

3. The mold buffer device according to claim 2, characterized in that: The mold buffer position controller uses as a target value a position detection value detected by a mold buffer position detector corresponding to the first drive shaft adjacent to the second drive shaft, or uses as a target value an average value of two or more position detection values ​​detected by a plurality of mold buffer position detectors corresponding to a plurality of the first drive shafts.

4. The mold buffer device according to claim 3, characterized in that: In the specific die cushion load control step, the die cushion position controller controls the second drive shaft so as to be within ±2 mm with respect to the target value.

5. The mold buffer device according to claim 4, characterized in that: The plurality of cushion lifting units respectively include a plurality of servo motors for driving the respective drive shafts. The mold buffer position controller calculates the torque command signal of the servo motor corresponding to the second drive shaft based on the target value and the position detection value of the mold buffer position detector corresponding to the second drive shaft, and adds a signal proportional to the signal obtained by differentiating the target value in time, or a signal proportional to the speed of the sliding part of the stamping machine, to the calculated torque command signal so that it is within ±2mm relative to the target value.

6. The mold buffer device according to claim 4, characterized in that: The plurality of cushion lifting units respectively include a plurality of servo motors for driving the respective drive shafts. The mold buffer position controller calculates the torque command signal of the servo motor corresponding to the second drive shaft based on the target value and the position detection value of the mold buffer position detector corresponding to the second drive shaft, and adds a signal obtained by multiplying a signal proportional to a signal obtained by differentiating the target value in time or a signal proportional to the speed of a sliding part of a stamping machine by a phase lead compensation element to the calculated torque command signal so that it is within ±2mm relative to the target value.

7. The mold buffer device according to claim 5 or 6, characterized in that: The die cushion device includes a plurality of angular velocity detectors for respectively detecting the rotational angular velocity of the plurality of servo motors. The die cushion position controller includes a stabilization controller that uses angular velocity signals respectively detected by the plurality of angular velocity detectors as angular velocity feedback signals.

8. The mold cushion device according to claim 5 or 6, characterized in that: The plurality of cushion lifting units include: a plurality of hydraulic cylinders including piston rods functioning as respective drive shafts; and a plurality of hydraulic pumps / motors that cause working fluid to act on die cushion load generating side pressurizing chambers of the plurality of hydraulic cylinders. The plurality of servomotors are connected to the plurality of hydraulic pump / motor shafts.

9. A control method for a mold cushion device, the mold cushion device comprising: a plurality of cushion lifting units, each of which has a plurality of drive shafts for supporting a cushion, and each of which drives the drive shafts to lift the cushion; a mold cushion load controller, which controls each of the drive shafts of the plurality of cushion lifting units to cause the cushion to generate a mold cushion load; and a mold cushion position controller, which controls each of the drive shafts of the plurality of cushion lifting units to control the position of the cushion, The control method of the die buffer device is characterized in that: The control method of the mold buffer device comprises the following steps: In a specific die buffer load control step, a selector is used to independently select, for each of the plurality of drive shafts of the cushion pad lifting units, whether to be a first drive shaft that performs die buffer load control based on the die buffer load controller or a second drive shaft that performs die buffer position control based on the die buffer position controller instead of performing die buffer load control based on the die buffer load controller; and In a specific die cushion load control process, the first drive shaft is controlled by the die cushion load controller, and the second drive shaft is controlled by the die cushion position controller.

10. The control method of the die buffer device according to claim 9, characterized in that: The die cushion device includes a plurality of die cushion position detectors, which detect positions of the cushion pads in the lifting direction corresponding to the positions of the respective drive shafts of the plurality of cushion pad lifting units and output position detection values ​​indicating the detected positions, respectively. In the specific die cushion load control step, the die cushion position controller controls the second drive shaft based on a position detection value detected by the die cushion position detector corresponding to the first drive shaft.

11. The control method of the die buffer device according to claim 10, characterized in that: The mold buffer position controller uses as a target value a position detection value detected by a mold buffer position detector corresponding to the first drive shaft adjacent to the second drive shaft, or uses as a target value an average value of two or more position detection values ​​detected by a plurality of mold buffer position detectors corresponding to a plurality of the first drive shafts.

12. The control method of the die buffer device according to claim 11, characterized in that: In the specific die cushion load control step, the die cushion position controller controls the second drive shaft so as to be within ±2 mm with respect to the target value.

13. The control method of the die cushion device according to any one of claims 9 to 12, characterized in that: The specific die cushion load control step includes a die cushion load control step when the die is arranged at a position offset from the center of the cushion pad, or a die cushion load control step when no material exists on a part of the plurality of drive shafts.

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