Mold cushioning device

Abstract

The present invention provides a mold cushion device that can well pre-pressurize a cushion pad when the cushion pad is in a mold cushion standby position. The mold cushion device of the present invention has a first oil cylinder (120) and a second oil cylinder (130) that are independently controlled simultaneously. In the case of pre-pressurizing the cushion pad (110), the first oil cylinder (120) is pressure-controlled through a first oil pressure circuit (140) so that the pressure of the lower chamber (120A) of the first oil cylinder (120) is pre-pressurized to a pre-set pressure, and the second oil cylinder (130) is position-controlled through a second oil pressure circuit (150) so that the cushion pad (110) is maintained in the mold cushion standby position. The force with which the first oil cylinder (120) raises the cushion pad (110) is balanced with the force (the force with which the cushion pad (110) is maintained in the mold cushion standby position) with which the second oil cylinder (130) lowers the cushion pad (110).

Description

Technical Field

[0001] This invention relates to a mold cushioning device, and more particularly to a technique for pressurizing (pre-pressurizing) the cushioning pad when it is in the mold cushioning standby position. Background Technology

[0002] In the past, a mold buffer device was proposed that could pre-pressurize the buffer pad when the buffer pad was in the mold buffer standby position (Patent Document 1).

[0003] Patent Document 1 describes a mold buffer device comprising: a hydraulic cylinder that supports a buffer pad and generates a buffering force in the mold when the slide of the stamping machine descends; a first hydraulic circuit connected to the head side hydraulic chamber (lower chamber) of the hydraulic cylinder; and a second hydraulic circuit connected to the rod side hydraulic chamber (upper chamber). When the buffer pad is in the mold buffer standby position, the second hydraulic circuit prevents the outflow of working oil from the upper chamber of the hydraulic cylinder through a pilot-driven check valve, and supplies pressurized oil to the lower chamber of the hydraulic cylinder through the first hydraulic circuit to pre-pressurize the buffer pad.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: JP 2017-113786

[0007] In the mold cushioning device described in Patent Document 1, when the cushioning pad is in the mold cushioning standby position, pressurized oil is supplied to the lower chamber of the hydraulic cylinder while preventing the outflow of working oil from the upper chamber, thus pre-pressurizing the cushioning pad. As a result, the working oil in the upper chamber of the hydraulic cylinder is compressed, and the cushioning pad rises slightly. For example, in a mold cushioning device with a maximum mold cushioning force of 2000kN, the cushioning pad rises by 9mm based on the cross-sectional area ratio of the upper and lower chambers of the cylinder due to a pre-pressurization of 400kN (20% of the maximum mold cushioning force). This rise is not an acceptable level for the cushioning pad.

[0008] Specifically, it is no longer a “permissible level” due to the following conditions (1) and (2).

[0009] (1) As the buffer pad rises, the upper surface (position) of the blank holder becomes relatively higher than the upper surface (position) of the lower die (punch), causing the blank (material) to flex, which affects the machining accuracy.

[0010] (2) Due to the rise of the pressure ring in (1), if the blank (material) is supplied from outside the press at the rising position, the track of the conveyor also needs to be adjusted.

[0011] Furthermore, the mold buffer device described in Patent Document 1 also has the problem of mold buffer standby position deviation (instability) during each pressing cycle.

[0012] Furthermore, as another problem arising from the "increase caused by compression," as in Patent Document 1... Figure 3 As shown, it can be seen that due to the compression of the working oil in the rod-side hydraulic chamber 120b of the hydraulic cylinder 120, the buffer pad 110 rises by an amount x. Therefore, if the buffer pad 110 does not drop by this amount x, the pressure in the upper chamber of the cylinder will not decrease to the containment pressure PR0 (the pressure corresponding to the system pressure of the present invention described later). Thus, if it does not decrease to the containment pressure PR0 level, the upward force that should be the buffering force will cancel out the downward force, resulting in the problem that the mold buffering force cannot immediately reach its target after the collision.

[0013] To address the issue of the mold buffer standby position rising due to pre-pressurization, the following control method is proposed: During the rise of the buffer pad via position control, the upper chamber of the hydraulic cylinder is closed to increase the pressure. By controlling this process, the final pressure value is made equal to the pre-pressurization pressure command, thus preventing the buffer pad from rising from the mold buffer standby position.

[0014] In this case, there is a problem with the pre-pressurization deviation in each pressing cycle. The deviation of the pre-pressurization at the mold buffer standby position (the difference in load during collision) is closely related to the stability of product quality. Summary of the Invention

[0015] The present invention is made in view of the following, and aims to provide a mold cushioning device that can effectively pre-pressurize the cushioning pad when the cushioning pad is in the mold cushioning standby position.

[0016] To achieve the above objectives, the mold buffer device according to the first aspect of the present invention is characterized by comprising: a first hydraulic cylinder that supports a buffer pad and causes the buffer pad to generate a mold buffering force when the slide of the stamping machine descends; a first hydraulic circuit that drives the first hydraulic cylinder; a first pressure command that outputs a first pressure command representing a mold buffering pressure corresponding to the mold buffering force; a first pressure detector that detects the pressure applied to the lower chamber of the first hydraulic cylinder; a first controller that controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector, such that the pressure applied to the lower chamber of the first hydraulic cylinder becomes the pressure corresponding to the first pressure command; a second hydraulic cylinder that supports the buffer pad and causes the buffer pad to move in a vertical direction; a second hydraulic circuit that drives the second hydraulic cylinder; a mold buffer position command that outputs a mold buffer position command representing the position of the buffer pad; and a mold buffer position detector. The system includes a first hydraulic controller that detects the position of the buffer pad, and a second controller that controls the second hydraulic circuit based on the mold buffer position command and the position of the buffer pad detected by the mold buffer position detector, so that the position of the buffer pad is corresponding to the mold buffer position command. The first pressure command outputs a second pressure command before pressing to pre-pressurize the pressure in the lower chamber of the first hydraulic cylinder to a preset pressure. The mold buffer position command outputs a first mold buffer position command before pressing to put the buffer pad in a mold buffer standby position. The first controller controls the first hydraulic circuit based on the second pressure command and the pressure detected by the first pressure detector, so that the pressure in the lower chamber of the first hydraulic cylinder is pre-pressurized to the pressure corresponding to the second pressure command. The second controller controls the second hydraulic circuit based on the first mold buffer position command, so that the buffer pad is in the mold buffer standby position.

[0017] According to a first aspect of the present invention, when the buffer pad is pre-pressurized while it is in the mold buffer standby position and the slide of the stamping machine is separated from the buffer pad, the pressure of the first hydraulic cylinder is controlled so that the pressure in the lower chamber of the first hydraulic cylinder is pre-pressurized to a predetermined pressure, and the position of the second hydraulic cylinder is controlled so that the buffer pad is in the mold buffer standby position. Since the buffer pad is positioned in the mold buffer standby position even when the desired pressure is supplied to the lower chamber of the first hydraulic cylinder for pre-pressurization, the buffer pad will not rise. Thus, the buffer pad can be accurately positioned in the mold buffer standby position, and the pressure in the lower chamber of the first hydraulic cylinder at the mold buffer standby position can be accurately pre-pressurized to the desired pressure, allowing molding to begin from the moment of impact using the pressure required for molding.

[0018] In the mold buffer device according to the second aspect of the present invention, pressure control of the first hydraulic cylinder implemented by the first controller and the first hydraulic circuit and position control of the second hydraulic cylinder implemented by the second controller and the second hydraulic circuit are performed simultaneously.

[0019] In the mold buffer device according to the third aspect of the present invention, preferably, the first hydraulic circuit comprises the following elements: a mold buffer pressure generating line connected to the lower chamber of the first hydraulic cylinder; a system pressure line connecting the upper chamber of the first hydraulic cylinder and a first accumulator for accumulating working fluid for the first system pressure; a first hydraulic pump / motor connected between the mold buffer pressure generating line and the system pressure line; and a first servo motor connected to the rotation shaft of the first hydraulic pump / motor, wherein the first controller controls the torque of the first servo motor based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector. By controlling the torque of the first servo motor, pressure control with good responsiveness to the pressure in the lower chamber of the first hydraulic cylinder can be achieved.

[0020] In the mold buffer device according to the fourth aspect of the present invention, the first hydraulic circuit is a closed hydraulic circuit comprising the following elements: a mold buffer pressure generating line connected to the lower chamber of the first hydraulic cylinder; a system pressure line connected to a first accumulator for accumulating working fluid for the first system pressure; a pilot-driven logic valve with port A connected to the mold buffer pressure generating line and port B connected to the system pressure line; a first solenoid valve for opening and closing the flow path between the mold buffer pressure generating line and the system pressure line; a pressure generator for generating pilot pressure acting on the pilot port of the logic valve; and a first hydraulic line connecting the pressure generator to the mold buffer pressure generating line. The first controller controls the pilot pressure based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector, controlling the pressure on the A port side of the logic valve, i.e., the pressure in the lower chamber of the first hydraulic cylinder, to a pressure corresponding to the first pressure command or the second pressure command. Thus, the first hydraulic circuit can be constructed using an inexpensive hydraulic circuit.

[0021] In the mold buffer device according to the fifth aspect of the present invention, preferably, a throttle is provided between the first hydraulic line or the pressure generator and the pilot port of the logic valve.

[0022] In the mold buffer device according to the sixth aspect of the present invention, preferably, the first hydraulic circuit has a second hydraulic line connecting the upper chamber of the first hydraulic cylinder and the system pressure line.

[0023] In the mold buffer device according to the seventh aspect of the present invention, preferably, the first hydraulic circuit has: a second solenoid valve that selectively applies the first system pressure or the pilot pressure to the pilot port of the logic valve.

[0024] In the mold buffer device according to the eighth aspect of the present invention, preferably, the pressure generator consists of a hydraulic pump disposed between the system pressure line and the pilot port of the logic valve and a third servo motor connected to the rotating shaft of the hydraulic pump. The first controller controls the torque of the third servo motor and controls the pilot pressure based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector.

[0025] In the mold buffer device according to the ninth aspect of the present invention, preferably, the mold buffer standby position is a position higher than the collision position at the start of pressing and molding. After outputting the first mold buffer position command, the mold buffer position commander outputs a second mold buffer position command to pre-accelerate the buffer pad before the slide reaches the collision position. The second controller controls the second hydraulic circuit based on the second mold buffer position command to pre-accelerate the buffer pad during the period from the mold buffer standby position to reaching the collision position. This suppresses the generation of surging pressure (impact pressure) during a collision.

[0026] In the mold buffer device according to the tenth aspect of the present invention, preferably, it includes: a second pressure command device that outputs a third pressure command representing a preset third pressure; and a second pressure detector that detects the pressure in the lower chamber of the second hydraulic cylinder. The second controller, during pressing, controls the second hydraulic circuit based on the third pressure command and the pressure detected by the second pressure detector, controlling the pressure in the lower chamber of the second hydraulic cylinder to the third pressure corresponding to the third pressure command. Accordingly, the control of the second hydraulic cylinder switches from position control to pressure control during pressing.

[0027] In the mold buffer device according to the 11th aspect of the present invention, preferably, the third pressure command is a pressure command corresponding to the auxiliary mold buffer force that assists the main mold buffer force generated by the first hydraulic cylinder or a pressure command that makes the mold buffer force generated by the second hydraulic cylinder zero.

[0028] When the third pressure command is a pressure command corresponding to the auxiliary mold buffering force, the second hydraulic cylinder can generate an auxiliary mold buffering force to compensate for the insufficient main mold buffering force generated by the first hydraulic cylinder when the main mold buffering force is insufficient to meet the desired mold buffering force. Furthermore, when the third pressure command is a pressure command that reduces the mold buffering force to zero, the second hydraulic cylinder is pressure-controlled so as not to obstruct the main mold buffering force generated by the first hydraulic cylinder.

[0029] In the mold buffer device according to the 12th aspect of the present invention, preferably, the mold buffer position commander outputs a third mold buffer position command corresponding to the position of the slide table during pressing, and the second controller controls the second hydraulic circuit based on the third mold buffer position command during pressing, so that the buffer pad moves to the mold buffer position corresponding to the position of the slide table. In this case, the second hydraulic cylinder is position-controlled during pressing so as not to obstruct the main mold buffering force generated by the first hydraulic cylinder.

[0030] In the mold buffer device according to the 13th aspect of the present invention, preferably, if the slide reaches the bottom dead center, the mold buffer position command device outputs a fifth mold buffer position command to move the buffer pad to the mold buffer standby position after outputting a fourth mold buffer position command to hold the buffer pad at the position corresponding to the bottom dead center for a certain period of time. If the slide reaches the bottom dead center, the second controller controls the second hydraulic circuit based on the fourth mold buffer position command and the fifth mold buffer position command, and after holding the buffer pad at the position corresponding to the bottom dead center for a certain period of time, moves the buffer pad to the mold buffer standby position.

[0031] In the mold buffer device according to the 14th aspect of the present invention, preferably, the second hydraulic circuit includes: a second hydraulic pump / motor connected between the upper and lower chambers of the second hydraulic cylinder; a second servo motor connected to the rotation shaft of the second hydraulic pump / motor; a second accumulator for storing working fluid of the second system pressure; a first pilot check valve provided in the flow path between the lower chamber of the second hydraulic cylinder and the second accumulator; and a second pilot check valve provided in the flow path between the upper chamber of the second hydraulic cylinder and the second accumulator, wherein the second controller executes: supplying working fluid from the second hydraulic pump / motor to the upper chamber of the second hydraulic cylinder. When working fluid is supplied, the second servo motor rotates in the first direction to supply working fluid to the upper chamber of the second hydraulic cylinder from the second hydraulic pump / motor, and the working fluid discharged from the lower chamber of the second hydraulic cylinder is pressurized in the second accumulator via the first pilot check valve. When working fluid is supplied to the lower chamber of the second hydraulic cylinder from the second hydraulic pump / motor, the second servo motor rotates in the second direction to supply working fluid to the lower chamber of the second hydraulic cylinder from the second hydraulic pump / motor, and the working fluid discharged from the upper chamber of the second hydraulic cylinder is pressurized in the second accumulator via the second pilot check valve.

[0032] The effects of the invention

[0033] According to the present invention, the buffer pad can be positioned precisely in the mold buffer standby position, and the pressure in the lower chamber of the first hydraulic cylinder at the mold buffer standby position can be pre-pressurized precisely to the desired pressure. Attached Figure Description

[0034] Figure 1 This is a structural diagram of a stamping machine equipped with the mold buffer device involved in this invention.

[0035] Figure 2 It means Figure 1 The diagram shows a first embodiment of the first and second hydraulic cylinders of the mold buffer device, and the first and second hydraulic circuits that drive the first and second hydraulic cylinders.

[0036] Figure 3 This is a block diagram illustrating a first embodiment of the first controller.

[0037] Figure 4 This is a block diagram illustrating an implementation of the second controller.

[0038] Figure 5 It is a waveform diagram showing the slide position, mold buffer position, pressure command (set pressure), and actual pressure of the pressing cycle when the mold buffer device is controlled by the first control method.

[0039] Figure 6It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operation state of the first and second hydraulic cylinders, etc., when the buffer pad is held in the mold buffer standby position before pre-pressurization.

[0040] Figure 7 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the initial operating state of the first and second hydraulic cylinders, etc., during pre-pressurization control when the buffer pad is held in the mold buffer standby position.

[0041] Figure 8 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operation state of the first and second hydraulic cylinders, etc., with the buffer pad held in the mold buffer standby position and pre-pressurization completed.

[0042] Figure 9 It is a waveform diagram showing the slide position, mold buffer position, pressure command (set pressure), and actual pressure of the pressing cycle 1 when the mold buffer device is controlled by the second control method.

[0043] Figure 10 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operating state of the first and second hydraulic cylinders, etc., during the pre-acceleration of the buffer pad.

[0044] Figure 11 It means Figure 1 The diagram shows a second embodiment of the first and second hydraulic cylinders of the mold buffer device and the first and second hydraulic circuits that drive the first and second hydraulic cylinders.

[0045] Figure 12 This is a block diagram illustrating a second implementation of the first controller.

[0046] Explanation of reference numerals in the attached figures

[0047] 10. Stamping Machinery

[0048] 12 pillars

[0049] 14 heads

[0050] 18 Guide Rail Section

[0051] 20 slide

[0052] 22 Crankshaft

[0053] 24-link

[0054] 26 Slide table position detector

[0055] 28 Crankshaft Encoder

[0056] 30 upper mold

[0057] 32 pad

[0058] 34 Lower mold

[0059] 100 Mold Buffer Device

[0060] 102 pressure ring

[0061] 104 Buffer Pin

[0062] 110 Cushion Pad

[0063] 112 Hydraulic Circuit

[0064] 114 First pressure detector

[0065] 115 Fixing part

[0066] 116 Mold Buffer Position Detector

[0067] 120 First Hydraulic Cylinder

[0068] 120A Lower Room

[0069] 120B Upper Room

[0070] 120C Piston Rod

[0071] 130 Second Hydraulic Cylinder

[0072] 130A Lower Room

[0073] 130B Upper Room

[0074] 130C Piston Rod

[0075] 140 First hydraulic circuit

[0076] 141 Mold buffer pressure generation pipeline

[0077] 142 System pressure lines

[0078] 143 First Accumulator

[0079] 144 First pressure detector

[0080] 150 Second hydraulic circuit

[0081] Hydraulic pipelines 151 and 152

[0082] 153 Second Accumulator

[0083] 154A First Pilot Check Valve

[0084] 154B Second Pilot Check Valve

[0085] 155A and 155B solenoid valves

[0086] 156 Second pressure detector

[0087] 157 Third pressure detector

[0088] 160 First Controller

[0089] 162 First Pressure Commander

[0090] 164, 165, 175 Amplifiers / PWM Controllers

[0091] 166 and 176 DC power supply units with power regeneration function

[0092] 167, 177 AC power supply

[0093] 170 Second Controller

[0094] 170A Mold Buffer Position Control Unit

[0095] 170B Mold Buffer Pressure Control Unit

[0096] 171 Mold Buffer Position Controller

[0097] 172 Mold Buffer Position Instructor

[0098] 173 Mold Buffer Pressure Controller

[0099] 174 Second Pressure Commander

[0100] Amplifiers 178 and 179

[0101] 180 hydraulic circuit

[0102] 182 Mold Buffer Pressure Generation Pipeline

[0103] 184 System pressure lines

[0104] 186 Accumulator

[0105] 188 Logic Valve

[0106] 190 Solenoid Valve No. 1

[0107] 191 First Hydraulic Line

[0108] 192 Second Hydraulic Line

[0109] 194. Solenoid Valve No. 2

[0110] 196. Orifice

[0111] Pressure detectors 198 and 199

[0112] 200 controller

[0113] 210 Pressure Commander

[0114] 220 amplifier

[0115] P / M1-1, P / M1-2 No. 1 Hydraulic Pump / Motor

[0116] SM1-1, SM1-2 First Servo Motor

[0117] P / M2 Second Hydraulic Pump / Motor

[0118] SM2 2nd Servo Motor

[0119] HP hydraulic pump

[0120] SM3 3rd Servo Motor Detailed Implementation

[0121] The preferred embodiments of the die cushion device of the present invention will be described in detail below with reference to the accompanying drawings.

[0122] Figure 1 This is a structural diagram of a stamping machine equipped with the mold buffer device involved in this invention.

[0123] Figure 1 The stamping machine 10 shown consists of a frame consisting of a support column 12, a head 14, and a crown (upper structural member of the frame) 16. The slide table 20 is freely guided to move in the vertical direction (vertical direction) by a guide rail 18 provided on the support column 12.

[0124] The slide 20 receives driving force from the servo motor via the crankshaft 22 and connecting rod 24, so that... Figure 1 The top moves in the vertical direction.

[0125] A slide position detector 26 for detecting the position of the slide 20 is provided on the head 14 side of the stamping machine 10, and a crankshaft encoder 28 for detecting the angle and angular velocity of the crankshaft 22 is provided on the crankshaft 22.

[0126] The slide 20 is equipped with an upper mold 30, and the head 14 is equipped with a lower mold 34 on the bolster 32.

[0127] Between the upper mold 30 and the lower mold 34, a pressure ring (anti-wrinkle pressure plate) 102 is arranged, which is supported by a buffer pad 110 on the lower side via a plurality of buffer pins 104, and the material is placed on the upper side (in contact).

[0128] The stamping machine 10 presses material between the upper die 30 and the lower die 34 by lowering the slide 20. The die buffer device 100 pushes the periphery of the pressed material from below.

[0129] The mold buffer device 100 mainly consists of the following elements: a pressure ring 102; a buffer pad 110 supporting the pressure ring 102 via a plurality of buffer pins 104; a first hydraulic cylinder 120 supporting the buffer pad 110 and causing the buffer pad 110 to generate mold buffering force; a second hydraulic cylinder 130 supporting the buffer pad 110 and causing the buffer pad 110 to move in the vertical direction; a first hydraulic circuit 140 driving the first hydraulic cylinder 120; a second hydraulic circuit 150 driving the second hydraulic cylinder 130; and a first controller 160 and a second controller 170 respectively controlling the first hydraulic circuit 140 and the second hydraulic circuit 150.

[0130] The first hydraulic cylinder 120 functions as a hydraulic cylinder that generates mold buffering force for the buffer pad 110 through pressure control via the first hydraulic circuit 140 and the first controller 160. The second hydraulic cylinder 130 functions as a hydraulic cylinder that moves the buffer pad 110 to a desired position in the vertical direction through position control via the second hydraulic circuit 150 and the second controller 170. That is, the first hydraulic cylinder 120 is pressure-controlled, and the second hydraulic cylinder 130 is mainly position-controlled; they are hydraulic cylinders with different functions.

[0131] [First Embodiment of the First and Second Hydraulic Circuits]

[0132] Figure 2 It means Figure 1 The diagram shows a first embodiment of the first and second hydraulic cylinders of the mold buffer device and the first and second hydraulic circuits that drive the first and second hydraulic cylinders.

[0133] Figure 2 The piston rod 120C of the first hydraulic cylinder 120 shown is connected to the lower surface of the buffer pad 110. The buffer pressure generating side pressurization chamber (hereinafter referred to as the "lower chamber") 120A of the first hydraulic cylinder 120 is connected to the mold buffer pressure generating line 141 of the first hydraulic circuit 140 via the hydraulic circuit 112 that supports the weight including the buffer pad 110, etc., and the rod side hydraulic chamber (hereinafter referred to as the "upper chamber") 120B of the first hydraulic cylinder 120 is connected to the system pressure line 142 of the first hydraulic circuit 140 via the hydraulic circuit 112.

[0134] The hydraulic circuit 112 supporting the weight includes a logic valve 112A, a solenoid valve 112B that switches the pilot pressure to the logic valve 112A, a pair of check valves 112C, a pressure relief valve 112D, and a first pressure detector 114.

[0135] The pilot port of logic valve 112A is pressured by opening / closing (ON / OFF) solenoid valve 112B to the lower chamber 120A (or mold buffer pressure generating line 141) of the first hydraulic cylinder 120 or the upper chamber 120B (system pressure line 142) of the first hydraulic cylinder 120.

[0136] If the solenoid valve 112B is closed without operating the stamping machine 10 (die buffer device 100), Figure 2 In the case of a certain state, pressure (at least an amount higher than the first system pressure corresponding to the weight) is applied to the pilot port of the logic valve 112A to the lower chamber 120A of the first hydraulic cylinder 120, and the logic valve 112A closes. As a result, the working fluid (working oil) in the lower chamber 120A of the first hydraulic cylinder 120 no longer flows out from the lower chamber 120A, and the first hydraulic cylinder 120 can support the weight of the buffer pad 110, etc.

[0137] On the other hand, if the solenoid valve 112B is opened while the stamping machine 10 (die buffer device 100) is running, a first system pressure is applied to the pilot port of the logic valve 112A. Since the first system pressure is lower than the pressure in the lower chamber 120A of the first hydraulic cylinder 120 or the die buffer pressure generating line 141, the logic valve 112A opens. As a result, the lower chamber 120A of the first hydraulic cylinder 120 and the die buffer pressure generating line 141 are connected via the logic valve 112A.

[0138] In addition, the first pressure detector 114 detects the pressure in the lower chamber 120A of the first hydraulic cylinder 120 and outputs a pressure signal representing the detected pressure to the first controller 160.

[0139] In addition, the hydraulic circuit 112 that supports the weight is not a necessary component of the mold buffer device involved in the present invention, but the first pressure detector 114 that detects the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is necessary.

[0140] In addition, such as Figure 2As shown, a mold buffer position detector 116 is provided between the fixing part 115 of the first hydraulic cylinder 120 and the second hydraulic cylinder 130 and the buffer pad 110 to detect the vertical position (mold buffer position) of the buffer pad 110. Alternatively, the mold buffer position detector can be built into the second hydraulic cylinder 130 and detect the position of the piston rod 130C in the extension and retraction direction as the mold buffer position, or it can be provided between the head 14 and the buffer pad 110.

[0141] <First Hydraulic Circuit>

[0142] Figure 2 The first hydraulic circuit 140 shown drives the first hydraulic cylinder 120 to generate mold buffering force in the buffer pad 110. It mainly includes: multiple (in this example, two) first hydraulic pumps / motors (first hydraulic pumps / motors) (P / M1-1, P / M1-2) connected between the mold buffering pressure generation line 141 and the system pressure line 142; first servo motors (SM1-1, SM1-2) respectively connected to the rotation shafts of the first hydraulic pumps / motors (P / M1-1, P / M1-2); a first accumulator 143 connected to the system pressure line 142; and a first pressure detector 144 for detecting the pressure of the first system.

[0143] The first hydraulic circuit 140 is supplied with working oil via a non-illustrated oil supply device through a connector 146A with a check valve connected to the mold buffer pressure generation line 141 and a connector 146B with a check valve connected to the system pressure line 142, thereby sealing in working oil at the given first system pressure.

[0144] The first accumulator 143, connected to the system pressure line 142, stores the working oil under the first system pressure. The first accumulator 143 is set to a given gas pressure and functions as an oil tank. Furthermore, the first system pressure is preferably set to a pressure within the range of 0.1 MPa to 1.0 MPa.

[0145] After the working oil of the first system pressure is sealed into the first hydraulic circuit 140, the oil supply device is disconnected from the connectors 146A and 146B. Then the first hydraulic circuit 140 becomes a closed hydraulic circuit in which the working oil will not flow in or out relative to the outside.

[0146] The pressure of the first system is detected by the first pressure detector 144. As long as it is not lower than the lower limit of the set first system pressure, there is no need to supply working oil to the first oil pressure circuit 140 from the oil supply device.

[0147] One port of the first hydraulic pump / motor (P / M1-1, P / M1-2) is connected to the mold buffer pressure generating line 141, and the other port is connected to the system pressure line 142.

[0148] In addition, a pressure relief valve 145 is installed between the mold buffer pressure generation line 141 and the system pressure line 142. This pressure relief valve 145 is designed to prevent damage to the hydraulic equipment by activating when abnormal pressure occurs (when pressure control is not possible, when a sudden abnormal pressure occurs).

[0149] Since the mold buffering force applied from the first hydraulic cylinder 120 to the buffer liner 110 can be represented by the product of the pressure in the lower chamber 120A of the first hydraulic cylinder 120 and the cross-sectional area of ​​the cylinder, controlling the mold buffering force means controlling the pressure in the lower chamber 120A of the first hydraulic cylinder 120.

[0150] The pressure of the lower chamber 120A of the first hydraulic cylinder 120 is controlled by the first servo motor (SM1-1, SM1-2) that drives the first hydraulic pump / motor (P / M1-1, P / M1-2). Further details regarding the pressure control by the first controller 160 will be described later.

[0151] Figure 2 The piston rod 130C of the second hydraulic cylinder 130 shown is connected to the lower surface of the buffer pad 110.

[0152] The lower chamber 130A of the second hydraulic cylinder 130 is connected to the hydraulic line 151 of the second hydraulic circuit 150, and the upper chamber 130B of the second hydraulic cylinder 130 is connected to the hydraulic line 152 of the second hydraulic circuit 150.

[0153] Preferably, in this example, the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130 is larger than the cross-sectional area of ​​the lower chamber 120A of the first hydraulic cylinder 120, and preferably the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130 is smaller than the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130.

[0154] If the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130 is increased, the pressure in the upper chamber 130B will be lower even if the downward load (= the reaction force of the upward load caused by pre-pressurization) is increased. A lower pressure in the upper chamber 130B will accelerate the depressurization of the upper chamber 130B during a collision. (This is because the time it takes for the pressure to decrease from the amount corresponding to the reaction force to the system pressure is negligible). As a result, a given buffering force can be generated in the lower chamber 120A of the first hydraulic cylinder 120 immediately after the collision. Furthermore, by reducing the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130, the upward movement speed of the piston rod 130C (buffer pad 110) corresponding to the amount of working oil supplied to the lower chamber 130A of the second hydraulic cylinder 130 can be accelerated.

[0155] <Second Hydraulic Circuit>

[0156] Figure 2The second hydraulic circuit 150 shown drives the second hydraulic cylinder 130 to move the buffer pad 110 in the vertical direction and maintain it in a desired position. It mainly includes: a second hydraulic pump / motor (second hydraulic pump / motor) (P / M2) connected between hydraulic lines 151 and 152; a second servo motor (SM2) connected to the rotation shaft of the second hydraulic pump / motor (P / M2); a second accumulator 153 that stores working oil pressure from the second system; and a flow path located between the lower chamber 130A of the second hydraulic cylinder 130 and the second accumulator 153. The first pilot check valve 154A; the second pilot check valve 154B located in the flow path between the upper chamber 130B of the second hydraulic cylinder 130 and the second accumulator 153; the solenoid valves 155A and 155B for applying pilot pressure to open the first pilot check valve 154A and the second pilot check valve 154B respectively; the second pressure detector 156 for detecting the pressure of the lower chamber 130A (hydraulic line 151) of the second hydraulic cylinder 130; and the third pressure detector 157 for detecting the pressure of the upper chamber 130B (hydraulic line 152) of the second hydraulic cylinder 130.

[0157] In addition, a pair of check valves 158A are installed between the hydraulic lines 151 and 152, and a pressure relief valve 158B is installed between the check valve 158A and the second accumulator 153 to prevent the generation of abnormal pressure.

[0158] The second hydraulic circuit 150 is supplied with working oil via connectors 159A and 159B with check valves connected to hydraulic lines 151 and 152, and the working oil at the given second system pressure is sealed in.

[0159] The working oil of the second system pressure is stored in the second accumulator 153, which is connected to the hydraulic lines 151 and 152 via the first pilot check valve 154A and the second pilot check valve 154B, respectively. The pressure of the second system is preferably set to the range of 0.1 MPa to 1.0 MPa, similar to the pressure of the first system stored in the first accumulator 143 of the first hydraulic circuit 140.

[0160] Since the second hydraulic pump / motor (P / M2) can spray working oil from two ports, one port of the second hydraulic pump / motor (P / M2) is connected to the hydraulic line 151, and the other port is connected to the hydraulic line 152.

[0161] Figure 2 Solenoid valves 155A and 155B are both in the closed state. However, when the buffer pad 110 is raised, solenoid valve 155A is opened and solenoid valve 155B is closed. On the other hand, when the buffer pad 110 is lowered, solenoid valve 155A is closed and solenoid valve 155B is opened.

[0162] Furthermore, when the second servo motor (SM2) raises the buffer pad 110, it drives the second hydraulic pump / motor (P / M2) to supply hydraulic oil to the lower chamber 130A of the second hydraulic cylinder 130 via hydraulic line 151 from one port of the second hydraulic pump / motor (P / M2). When the buffer pad 110 lowers, it drives the second hydraulic pump / motor (P / M2) to supply hydraulic oil to the upper chamber 130B of the second hydraulic cylinder 130 via hydraulic line 152 from the other port of the second hydraulic pump / motor (P / M2).

[0163] When the buffer pad 110 is raised (when the lower chamber 130A of the second hydraulic cylinder 130 is pressurized), the second hydraulic pump / motor (P / M2) is driven to supply pressurized oil to the lower chamber 130A of the second hydraulic cylinder 130. However, in this case, the solenoid valve 155A is opened, and the second system pressure stored in the second accumulator 153 is applied to the first pilot check valve 154A via the solenoid valve 155A. Therefore, the first pilot check valve 154A remains closed.

[0164] On the other hand, since the solenoid valve 155B is closed, the pressure of the hydraulic line 151 (lower chamber 130A of the second hydraulic cylinder 130) is applied to the second pilot check valve 154B via the solenoid valve 155B. Therefore, the second pilot check valve 154B is opened, and the pressure of the upper chamber 130B of the second hydraulic cylinder 130 is depressurized to the second system pressure.

[0165] Therefore, the working oil ejected from one port of the second hydraulic pump / motor (P / M2) is supplied to the lower chamber 130A of the second hydraulic cylinder 130 via the hydraulic line 151. The working oil discharged from the upper chamber 130B of the second hydraulic cylinder 130, which accompanies the rise of the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130, flows into the other port of the second hydraulic pump / motor (P / M2) and is stored in the second accumulator 153 via the second pilot check valve 154B.

[0166] Furthermore, when the buffer pad 110 is lowered (when the upper chamber 130B of the second hydraulic cylinder 130 is pressurized), the second hydraulic pump / motor (P / M2) is driven to supply pressurized oil to the upper chamber 130B of the second hydraulic cylinder 130. In this case, the solenoid valve 155B is opened, and the second system pressure stored in the second accumulator 153 is applied to the second pilot check valve 154B via the solenoid valve 155B. Therefore, the second pilot check valve 154B remains closed.

[0167] On the other hand, since the solenoid valve 155A is closed, the pressure of the hydraulic line 152 (the upper chamber 130B of the second hydraulic cylinder 130) is applied to the first pilot check valve 154A via the solenoid valve 155A. Therefore, the first pilot check valve 154A is opened, and the pressure in the lower chamber 130A of the second hydraulic cylinder 130 is depressurized to the second system pressure.

[0168] Therefore, the working oil ejected from the other port of the second hydraulic pump / motor (P / M2) is supplied to the upper chamber 130B of the second hydraulic cylinder 130 via the hydraulic line 152. As the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130 descends, the working oil discharged from the lower chamber 130A of the second hydraulic cylinder 130 is drawn into the port of the second hydraulic pump / motor (P / M2). Furthermore, since the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130 is larger than that of the lower chamber 130A, a portion of the working oil flowing into the second hydraulic pump / motor (P / M2) when the buffer pad 110 descends is supplied from the second accumulator 153.

[0169] In this way, the second hydraulic pump / motor (P / M2) can raise the buffer pad 110 by supplying working oil to the lower chamber 130A of the second hydraulic cylinder 130, and lower the buffer pad 110 by supplying working oil to the upper chamber 130B of the second hydraulic cylinder 130.

[0170] <Controller 1>

[0171] Next, the function of the first controller 160 of the first hydraulic circuit 140 that controls and drives the first hydraulic cylinder 120 will be explained.

[0172] Figure 3 This is a block diagram illustrating a first embodiment of the first controller.

[0173] like Figure 3 As shown, for the first controller 160, a pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is applied from the first pressure detector 114, and a slide position signal representing the position of the slide 20 is applied from the slide position detector 26.

[0174] The first controller 160 includes a first pressure command device 162, which applies a slide position signal detected by the slide position detector 26 in order to input a pressure command (including a mold buffer pressure command) corresponding to the position of the slide 20 to the first pressure command device 162.

[0175] The first pressure command unit 162 outputs a first pressure command that represents the mold buffer pressure corresponding to the mold buffer force during pressing and forming, and a second pressure command that pre-pressurizes the pressure of the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure before pressing and forming (when the buffer pad 110 is in the mold buffer standby position). In addition, the output timing of the first pressure command, the second pressure command, etc. is controlled based on the slide position signal.

[0176] In addition, in this example, the first pressure command unit 162 outputs a stepped first pressure command as described later, and outputs a second pressure command for pre-pressurization that represents the same pressure as the first pressure command for a certain period before the collision. Therefore, there is no change in pressure command between the first pressure command and the second pressure command.

[0177] Furthermore, the first pressure command unit 162 outputs the first pressure command, the second pressure command, etc., based on the slide position signal, but it is not limited to this. It can also output the first pressure command, the second pressure command, etc., based on the crank angle signal detected by the crankshaft encoder 28. This is because the slide position can be converted from the crank angle.

[0178] The first controller 160, in order to control the pressure of the lower chamber 120A of the first hydraulic cylinder 120 as indicated by the pressure commands (first and second pressure commands) output from the first pressure command unit 162 and the pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the first pressure detector 114, calculates torque commands for driving the first servo motors (SM1-1, SM1-2). When calculating the torque commands, the angular velocity of the drive shaft of the first servo motors (SM1-1, SM1-2) is preferably used as an angular velocity feedback signal to ensure dynamic stability.

[0179] The first controller 160 controls the pressure of the lower chamber 120A of the first hydraulic cylinder 120 by outputting torque commands calculated using pressure commands, pressure signals, etc., to the first servo motors (SM1-1, SM1-2) via amplifiers and PWM controllers 164 and 165.

[0180] However, the torque output direction of the first servo motor (SM1-1, SM1-2) during pressure control when pre-pressurizing the lower chamber 120A of the first hydraulic cylinder 120 is opposite to that during the descent of the slide 20 when the slide 20 collides with the buffer pad 110 (the upper mold 30 equipped on the slide 20 impacts the buffer pad 110 supported by the first hydraulic cylinder 120 through the material, the pressure ring 102 and the buffer pin 104) until the bottom dead center is reached (during pressing).

[0181] That is, the pressurized oil ejected from the lower chamber 120A of the first hydraulic cylinder 120 by the power received from the slide table 20 via the buffer pad 110 flows into the first hydraulic pump / motor (P / M1-1, P / M1-2), and the first hydraulic pump / motor (P / M1-1, P / M1-2) functions as a hydraulic motor. Through the first hydraulic pump / motor (P / M1-1, P / M1-2), the first servo motor (SM1-1, SM1-2) passively functions as a generator.

[0182] In other words, the force transmitted from the slide 20 to the first hydraulic cylinder 120 via the buffer pad 110 compresses the lower chamber 120A of the first hydraulic cylinder 120, generating mold buffer pressure. Simultaneously, the mold buffer pressure causes the first hydraulic pump / motor (P / M1-1, P / M1-2) to function as a hydraulic motor. The rotational shaft torque generated by the first hydraulic pump / motor (P / M1-1, P / M1-2) counteracts the driving torque of the first servo motor (SM1-1, SM1-2), causing the first servo motor (SM1-1, SM1-2) to rotate and control the mold buffer pressure. As a result, the mold buffer pressure is controlled according to the driving torque of the first servo motor (SM1-1, SM1-2).

[0183] In the generation of mold buffer pressure, the power generated by the first servo motor (SM1-1, SM1-2) is used to regenerate the AC power 167 via amplifier and PWM (pulse width modulation) controllers 164 and 165 and DC power supply device 166 with power regeneration function.

[0184] In addition, the first controller 160 performs the following pressure control: if the slide 20 reaches the bottom dead center, it depressurizes the pressure in the lower chamber 120A of the first hydraulic cylinder 120 and transitions to the first system pressure; pressure control of the amount of product ejection force required to raise the second hydraulic cylinder 130 after locking to eject the product; and pressure control of the amount of weight of the buffer pad 110, etc., during the standby period at the mold buffer standby position of the buffer pad 110 (except for the period of pre-pressurization).

[0185] <Second Controller>

[0186] Next, the function of the second controller 170 of the second hydraulic circuit 150 that controls and drives the second hydraulic cylinder 130 will be explained.

[0187] Figure 4 This is a block diagram illustrating an implementation of the second controller.

[0188] like Figure 4As shown, for the second controller 170, a mold buffer position signal indicating the position of the buffer pad 110 (mold buffer position) is applied from the mold buffer position detector 116, a slide position signal indicating the position of the slide 20 is applied from the slide position detector 26, and a pressure signal indicating the pressure of the lower chamber 130A of the second hydraulic cylinder 130 is applied from the second pressure detector 156.

[0189] The second controller 170 in this example includes a mold buffer position control unit 170A and a mold buffer pressure control unit 170B.

[0190] The mold buffer position control unit 170A mainly includes a mold buffer position controller 171 and a mold buffer position commander 172. The mold buffer position commander 172 is fed a slide position signal from the slide position detector 26, and outputs a mold buffer position command for controlling the position of the buffer pad 110 during periods other than pressing and molding based on the input slide position signal.

[0191] In this example, the mold buffer position instruction 172 outputs the following instructions: a first mold buffer position instruction to put the buffer pad 110 in the mold buffer standby position before pressing and molding; a second mold buffer position instruction to accelerate (pre-accelerate) the buffer pad 110 during the period from the mold buffer standby position to the collision position after the first mold buffer position instruction is output; a fourth mold buffer position instruction to keep the buffer pad 110 in a position corresponding to the bottom dead center of the slide 20; and a fifth mold buffer position instruction to move the buffer pad 110 to the mold buffer standby position after a certain period of time after the fourth mold buffer position instruction is output.

[0192] When the second hydraulic cylinder 130 is in position control mode, the mold buffer position controller 171 calculates a torque command for controlling the second servo motor (SM2) to move or maintain the position of the buffer pad 110 as instructed by the mold buffer position command output from the mold buffer position commander 172 and the mold buffer position signal detected by the mold buffer position detector 116. When calculating the torque command, the angular velocity of the drive shaft of the second servo motor (SM2) is preferably used as an angular velocity feedback signal to ensure dynamic stability.

[0193] Then, when the second hydraulic cylinder 130 is in position control state, the mold buffer position controller 171 of the second controller 170 outputs a torque command calculated using mold buffer position instructions, mold buffer position signals, etc., to the second servo motor (SM2) via an amplifier and PWM controller 175, so as to move the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130 in the vertical direction or keep the buffer pad 110 in the desired position.

[0194] Furthermore, when the mold buffer position controller 171 outputs a torque command to supply working oil to the lower chamber 130A of the second hydraulic cylinder 130, it outputs a drive signal to open the solenoid valve 155A via amplifier 178 to the solenoid valve 155A, thereby enabling the supply of working oil to the lower chamber 130A of the second hydraulic cylinder 130 and the outflow of working oil from the upper chamber 130B. Additionally, when the mold buffer position controller 171 outputs a torque command to supply working oil to the upper chamber 130B of the second hydraulic cylinder 130, it outputs a drive signal to open the solenoid valve 155B via amplifier 179 to the solenoid valve 155B, thereby enabling the supply of working oil to the upper chamber 130B of the second hydraulic cylinder 130 and the outflow of working oil from the lower chamber 130A.

[0195] On the other hand, the mold buffer pressure control unit 170B mainly includes a mold buffer pressure controller 173 and a second pressure command unit 174. A slide position signal is applied to the second pressure command unit 174 from the slide position detector 26, and the second pressure command unit 174 outputs a mold buffer pressure command (third pressure command) for pressure control of the second hydraulic cylinder 130 during pressing and molding based on the input slide position signal.

[0196] In this example, the second pressure command unit 174 outputs a pressure command corresponding to the auxiliary mold buffer force (main mold buffer force) generated by the first hydraulic cylinder 120 in the pressing process, or outputs a pressure command that makes the mold buffer force generated by the second hydraulic cylinder 130 zero.

[0197] When the second hydraulic cylinder 130 is in pressure control mode, the mold buffer pressure controller 173 calculates a torque command for driving the second servo motor (SM2) in order to control the pressure of the lower chamber 130A of the second hydraulic cylinder 130, based on the mold buffer pressure command output from the second pressure command unit 174 and the pressure signal output from the second pressure detector 156, as a pressure command. When calculating the torque command, the angular velocity of the drive shaft of the second servo motor (SM2) is preferably used as an angular velocity feedback signal to ensure dynamic stability.

[0198] Then, when the second hydraulic cylinder 130 is in pressure control state, the mold buffer pressure controller 173 of the second controller 170 outputs the torque command calculated using pressure command, pressure signal, etc., to the second servo motor (SM2) via the amplifier and PWM controller 175, thereby controlling the pressure of the lower chamber 130A of the second hydraulic cylinder 130 to a pressure corresponding to the auxiliary mold buffer force, or to a pressure that makes the mold buffer force generated by the second hydraulic cylinder 130 zero.

[0199] In addition, when the mold buffer pressure controller 173 outputs a torque command to supply working oil to the lower chamber 130A of the second hydraulic cylinder 130, it outputs a drive signal to open the solenoid valve 155A via the amplifier 178 to the solenoid valve 155A, thereby enabling the pressurization of the lower chamber 130A of the second hydraulic cylinder 130 and making the upper chamber 130B the second system pressure.

[0200] Furthermore, when the second hydraulic cylinder 130 is controlled to generate an auxiliary mold buffering force, the second servo motor (SM2) functions as a generator, and the power generated by the second servo motor (SM2) is regenerated by the AC power supply 177 via the amplifier and PWM controller 175 and the DC power supply device 176 with power regeneration function.

[0201] On the other hand, when the pressure of the second hydraulic cylinder 130 is controlled so that the mold buffering force generated by the second hydraulic cylinder 130 becomes zero, the second hydraulic cylinder 130 will not hinder the mold buffering force generated by the first hydraulic cylinder 120.

[0202] The position control of the second hydraulic cylinder 130 by the mold buffer position control unit 170A and the pressure control of the second hydraulic cylinder 130 by the mold buffer pressure control unit 170B can be switched according to the position of the slide table 20 and the crank angle detected by the crankshaft encoder 28.

[0203] Furthermore, the second controller 170 can also perform position control only on the second hydraulic cylinder 130. In this case, the mold buffer pressure control unit 170B is not required in the second controller 170.

[0204] Furthermore, during compression molding, the mold buffer position controller 172 of the mold buffer position control unit 170A outputs a mold buffer position command (third mold buffer position command) corresponding to the position of the slide 20. The mold buffer position controller 171 preferably controls the position of the second hydraulic cylinder 130 based on the third mold buffer position command and the mold buffer position signal. This allows for position control of the second hydraulic cylinder 130 so as not to obstruct the mold buffering force generated by the first hydraulic cylinder 120.

[0205] According to the first embodiment described above, when the buffer pad 110 is pre-pressurized in the mold buffer standby position, the pressure of the first hydraulic cylinder 120 is controlled and pressurized (pre-pressurized) so that the desired pressure is applied to the lower chamber 120A of the first hydraulic cylinder 120, and the position of the second hydraulic cylinder 130 is controlled to keep the buffer pad 110 in the mold buffer standby position. Therefore, the buffer pad 110 can be pre-pressurized and the buffer pad 110 can be accurately positioned in the mold buffer standby position.

[0206] Furthermore, by ensuring that the buffer pad 110 is precisely positioned in the mold buffer standby position, during pre-pressurization, the upper surface of the pressure ring 102 can be prevented from becoming higher than the upper surface of the lower mold 34, thus avoiding deflection of the blank (material) caused by the pressure ring 102 and maintaining good processing accuracy.

[0207] Furthermore, since the rise of the blank holder 102 is suppressed, the conveyor track correction is no longer required when supplying blanks (materials) from outside the press.

[0208] Furthermore, the stability of product quality is maintained due to the pre-pressurization of the buffer pad 110 in each cycle of the press and the stable standby position of the mold buffer.

[0209] Furthermore, since the pressure of the upper chamber 120B of the first hydraulic cylinder 120 can be maintained at a given first system pressure during pre-pressurization, the first hydraulic cylinder 120 can generate the target mold buffer force immediately after the collision.

[0210] Furthermore, in the first embodiment described above, when pressure control is applied to the first hydraulic cylinder 120 and the second hydraulic cylinder 130, for the sake of simplicity, the pressure of the upper chamber 120B of the first hydraulic cylinder 120 (first system pressure) and the pressure of the upper chamber 130B of the second hydraulic cylinder 130 (second system pressure) are not considered. However, in order to accurately control the mold buffering force generated by the buffer pad 110, it is desirable to consider the pressure of the upper chamber 120B of the first hydraulic cylinder 120.

[0211] <First Control Method for Mold Buffer Device>

[0212] Next, the first control method of the mold buffer device will be described.

[0213] Figure 5 It is a waveform diagram showing the slide position, mold buffer position, pressure command (set pressure), and actual pressure of the pressing cycle when the mold buffer device is controlled by the first control method.

[0214] The first control method of the mold buffer device 100 is particularly characterized by pre-pressurizing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure before pressing.

[0215] Before pressing, since no pressing force from the slide 20 of the stamping machine 10 is applied to the buffer pad 110, if the lower chamber 120A of the first hydraulic cylinder 120 is supplied with pressurized oil only to pre-pressurize the lower chamber 120A of the first hydraulic cylinder 120, the piston rod 120C (buffer pad 110) of the first hydraulic cylinder 120 will rise and the lower chamber 120A of the first hydraulic cylinder 120 cannot be pre-pressurized.

[0216] Therefore, in this invention, mold buffer pressure control and mold buffer position control are performed simultaneously. The first hydraulic cylinder 120 is pressure controlled for pre-pressurization, and the second hydraulic cylinder 130 is position controlled so that the buffer pad 110 does not move from the mold buffer standby position.

[0217] Figure 6 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operating state of the first and second hydraulic cylinders, etc., in which the buffer pad is held in the mold buffer standby position before pre-pressurization. Figure 5 The waveform diagram for cycle 1 shows the state before the start of pre-pressurization, t0.

[0218] In this case, the second controller 170 controls the position of the second hydraulic cylinder 130 by issuing a mold buffer position command (first mold buffer position command) that positions the buffer pad 110 in the mold buffer standby position X1. To maintain the buffer pad 110 in the mold buffer standby position X1 as instructed by the first mold buffer position command, the second controller 170 rotates the second servo motor (SM2) in one direction (first direction) or the other direction (second direction) to adjust the pressure applied to the lower chamber 130A and the upper chamber 130B of the second hydraulic cylinder 130 by the second hydraulic pump / motor (P / M2) driven by the second servo motor (SM2). With the first hydraulic cylinder 120 supporting an amount corresponding to the weight of the buffer pad 110, the cross-sectional area × pressure of the lower chamber 130A and the cross-sectional area × pressure of the upper chamber 130B of the second hydraulic cylinder 130 are approximately the same when the buffer pad 110 is held in the mold buffer standby position X1.

[0219] On the other hand, while the second controller 170 is controlling the position of the second hydraulic cylinder 130, the first controller 160 controls the pressure of the first hydraulic cylinder 120 so that the first hydraulic cylinder 120 assists in supporting an amount corresponding to the weight of the buffer pad 110, etc. That is, the first controller 160 controls the first servo motors (SM1-1, SM1-2) to apply a pressure P0 from the first hydraulic pump / motor (P / M1-1, P / M1-2) to the lower chamber 120A of the first hydraulic cylinder 120 to support an amount corresponding to the weight of the buffer pad 110, etc.

[0220] Afterwards, slide 20 descends. If the slide position reaches position X0, which is a height H higher than the mold buffer standby position X1, then... Figure 5 At time t0), the first controller 160 begins to pressurize the lower chamber 120A of the first hydraulic cylinder 120 to the set pressure P1.

[0221] Figure 7 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the initial operating state of the first and second hydraulic cylinders, etc., during the pre-pressurization control when the buffer pad is held in the mold buffer standby position.

[0222] In this case, the first controller 160 drives the first hydraulic pump / motor (P / M1-1, P / M1-2) via the first servo motor (SM1-1, SM1-2) to supply hydraulic oil to the lower chamber 120A of the first hydraulic cylinder 120 based on a second pressure command that causes the pre-pressurization to a preset pressure P1, thereby controlling the pressure so that the lower chamber 120A of the first hydraulic cylinder 120 reaches the set pressure P1.

[0223] By pressurizing the lower chamber 120A of the first hydraulic cylinder 120, the first hydraulic cylinder 120... Figure 7 A force is applied to the cushioning pad 110 to make it rise, as shown by the middle arrow.

[0224] Then, if the buffer pad 110 needs to rise through pre-pressurization control, the second controller 170 will control the position of the second hydraulic cylinder 130 to keep the buffer pad 110 in the mold buffer standby position (not rising).

[0225] Figure 8 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operation of the first and second hydraulic cylinders, etc., with the buffer pad held in the mold buffer standby position and pre-pressurization completed.

[0226] In this situation, the buffer pad 110 remains in the mold buffer standby position. Since the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is pressurized (compressed) to the set pressure P1, no working oil flows from the first hydraulic pump / motor (P / M1-1, P / M1-2) into the lower chamber 120A of the first hydraulic cylinder 120. However, the first controller 160, in order to maintain the pressure in the lower chamber 120A of the first hydraulic cylinder 120 at the set pressure P1, works with… Figure 7 Similarly, the first servo motor (SM1-1, SM1-2) is continuously driven for pressure control so that the pressure on the port side of one of the first hydraulic pumps / motors (P / M1-1, P / M1-2) becomes the set pressure P1.

[0227] On the other hand, the second controller 170 performs position control on the second hydraulic cylinder 130 so that the buffer pad 110 is held in the mold buffer standby position. As a result, the second hydraulic cylinder 130 applies a force (a depressing force) to the buffer pad 110 that cancels out the pushing force applied to the buffer pad 110 by the first hydraulic cylinder 120.

[0228] Here, the pushing force F1 exerted by the first hydraulic cylinder 120 on the buffer pad 110 can be characterized by the following formula.

[0229] [Mathematical Expression 1]

[0230] F1 = Pressure of the lower chamber 120A of the first hydraulic cylinder 120 (set pressure P1) × cross-sectional area

[0231] The depressurization force F2 exerted by the second hydraulic cylinder 130 on the buffer liner 110 is characterized by the following formula.

[0232] [Mathematical Expression 2]

[0233] F2 = Pressure in the upper chamber 130B of the second hydraulic cylinder 130 × Cross-sectional area

[0234] Therefore, with the buffer pad 110 held in the mold buffer standby position and pre-pressurization completed, F1 = F2.

[0235] Furthermore, in Formula 1, the first system pressure of the upper chamber 120B of the first hydraulic cylinder 120 is not considered, and in Formula 2, the second system pressure of the lower chamber 130A of the second hydraulic cylinder 130 is not considered. However, when the first system pressure and the second system pressure are approximately the same and the cross-sectional area of ​​the upper chamber 120B of the first hydraulic cylinder 120 and the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130 are approximately the same, the forces generated by the first system pressure and the second system pressure roughly cancel each other out, and the force F1 that pushes the buffer pad 110 up and the force F2 that presses the buffer pad 110 down are approximately equal.

[0236] like Figure 5 As shown, pre-pressurization is completed when the slide reaches the mold buffer standby position X1 (time t1).

[0237] The first controller 160 performs pressure control on the first hydraulic cylinder 120 so that after the slide reaches the mold buffer standby position X1 (after collision), the pressure in the lower chamber 120A of the first hydraulic cylinder 120 is maintained at the set pressure P1. In this example, the second pressure command that pre-pressurizes the pressure in the lower chamber 120A of the first hydraulic cylinder 120 to the preset pressure P1 before pressing is the same as the first pressure command that represents the mold buffer pressure P1 corresponding to the mold buffer force during pressing. Therefore, the first controller 160 performs pressure control on the first hydraulic cylinder 120 based on the same pressure command during the period from time t0 to time t1 and during the pressing period, i.e., from time t1 to time t2 (the time when the slide reaches the bottom dead center).

[0238] On the other hand, if the slide position reaches the mold buffer standby position X1 (time t1), the second controller 170 controls the position of the second hydraulic cylinder 130 based on the mold buffer position command (third mold buffer position command) corresponding to the slide position, thereby not hindering the mold buffer force generated by the first hydraulic cylinder 120.

[0239] Furthermore, if the slide position reaches the mold buffer standby position X1, the second controller 170 can replace the position control of the second hydraulic cylinder 130 and switch to pressure control based on the third pressure command. The third pressure command is either a pressure command corresponding to the auxiliary mold buffer force that assists the mold buffer force (main mold buffer force) generated by the first hydraulic cylinder 120 during pressing and molding, or a pressure command that makes the mold buffer force generated by the second hydraulic cylinder 130 zero.

[0240] Next, if the slide reaches the bottom dead center, the first controller 160 will depressurize the lower chamber 120A of the first hydraulic cylinder 120 during a certain period from the moment t2 when the bottom dead center is reached to the start time t3 when the product is ejected (the locking period during which the buffer pad 110 is held in the position corresponding to the bottom dead center), and perform pressure control to transition to the first system pressure. After the locking is completed, the first controller 160 performs the pressure control required for product ejection.

[0241] On the other hand, if the slide position reaches the bottom dead center, the second controller 170 will, within a certain time period (lock-up period) from the time t2 to the time t3 when the bottom dead center is reached, perform position control (lock-up control) based on the fourth mold buffer position command to keep the buffer pad 110 in the position corresponding to the bottom dead center for a certain time. After that, based on the fifth mold buffer position command, the buffer pad 110 will be raised, and position control will be performed again to move to the mold buffer standby position.

[0242] According to the first control method of the mold buffer device, pre-pressurization is performed before pressing to make the pressure of the lower chamber 120A of the first hydraulic cylinder 120 reach the set pressure P1. Since the force applied from the second hydraulic cylinder 130 to the buffer pad 110 is immediately zero after the collision, pressing can begin from the moment of collision with the mold buffer force required for molding (the set pressure P1 corresponding to the mold buffer force).

[0243] Furthermore, by pre-pressurizing before molding, the ripple pressure during impact can be reduced compared to not pre-pressurizing.

[0244] Furthermore, since the buffer pad 110 is held in the mold buffer standby position by the second hydraulic cylinder 130 before pressing, the buffer pad 110 will not be pushed up even if the collision position is mistaken. Since the position control and pressure control are separate, there is an advantage that even if the position control that holds the buffer pad 110 in the mold buffer standby position is roughly switched to pressure control (or other position control) after the collision, it will not cause any problems.

[0245] Furthermore, the mold buffer standby position can be freely set, thus enabling a wider variety of molds to be handled with buffer pins of the same length.

[0246] <Second Control Method for Mold Buffer Device>

[0247] Next, the second control method of the mold buffer device will be explained.

[0248] Figure 9 It is a waveform diagram showing the slide position, mold buffer position, pressure command (set pressure), and actual pressure of the pressing cycle 1 when the mold buffer device is controlled by the second control method.

[0249] As a second control method for mold buffer devices, and using Figure 5 Compared to the first control method for the mold buffer device described above, the second control method for the mold buffer device does not require the addition of pre-acceleration control for the buffer pad 110 before pressing. Furthermore, detailed descriptions of the parts common to the first control method are omitted in the second control method for the mold buffer device.

[0250] like Figure 9 As shown, the mold buffer standby position X1' is a position above the collision position X2 at the start of pressing and molding by a height H2.

[0251] When slide 20 descends, if the slide position reaches position X0 which is higher than the mold buffer standby position X1' by a height H1 ( Figure 9 At time t0), similar to the first control method, the first controller 160 begins to pressurize the lower chamber 120A of the first hydraulic cylinder 120 to a pre-pressurization of the set pressure P1. In addition, the second controller 170 performs position control on the second hydraulic cylinder 130 so that the buffer pad 110 is held in the mold buffer standby position X1'.

[0252] Next, the mold buffer position instruction 172 of the second controller 170, before the slide reaches the collision position ( Figure 9 At time t1), the output of the first mold buffer position command, which represents the mold buffer standby position X1', is replaced by the output of the second mold buffer position command, which pre-accelerates the buffer pad 110.

[0253] The second controller 170 controls the position of the second hydraulic cylinder 130 based on the second mold buffer position command, so that the buffer pad 110 accelerates (pre-accelerates) before the collision.

[0254] Figure 10 It means and Figure 2 The diagram of the drive section of the same mold buffer device mainly shows the operating state of the first and second hydraulic cylinders, etc., during the pre-acceleration of the buffer pad.

[0255] The second controller 170 controls the position of the second hydraulic cylinder 130 by issuing a second mold buffer position command that pre-accelerates the buffer pad 110. That is, the second controller 170 controls the second servo motor (SM2) to supply working oil from the second hydraulic pump / motor (P / M2) to the upper chamber 130B of the second hydraulic cylinder 130, thereby causing the buffer pad 110 to descend (pre-accelerate in the downward direction) through the second hydraulic cylinder 130.

[0256] During pre-acceleration, the first controller 160 continuously performs pressure control so that the pressure in the lower chamber 120A of the first hydraulic cylinder 120 becomes the pre-pressurization set pressure P1. However, the torque output direction of the first servo motor (SM1-1, SM1-2) when the buffer pad 110 is in the mold buffer standby position is opposite to the torque output direction of the first servo motor (SM1-1, SM1-2) during pre-acceleration.

[0257] Then, if the slide position reaches the collision position X2 at the start of the pressing process... Figure 9At time t2), the second controller 170 controls the position of the second hydraulic cylinder 130 based on the mold buffer position command (third mold buffer position command) corresponding to the current slide position. This prevents the second hydraulic cylinder 130 from obstructing the mold buffer force generated by the first hydraulic cylinder 120. Furthermore, the second controller 170 can switch the control of the second hydraulic cylinder 130 from position control to pressure control in the event of a collision.

[0258] On the other hand, the first controller 160 continuously controls the pressure of the first hydraulic cylinder 120 in the same way as the pressure control during pre-acceleration.

[0259] Figure 9 At time t3, the slide reaches the bottom dead center, and at time t4, the lock ends. The first controller 160 and the second controller 170, like the first control method, switch to different pressure commands and position commands at these times t3 and t4 to perform pressure control and position control.

[0260] In addition, in the position control of the second controller 170 that pre-accelerates the buffer pad 110, it is preferable to reduce the difference between the speed of the slide 20 and the speed of the buffer pad 110 during a collision.

[0261] According to the second control method of the mold buffer device, since the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to the set pressure P1 and the pad 110 is pre-accelerated, the molding can start from the moment of impact with the mold buffer force required for molding. In addition, the ripple pressure during the impact can be further reduced.

[0262] [Second Embodiment of the First and Second Hydraulic Circuits]

[0263] Figure 11 It means Figure 1 The diagram shows a second embodiment of the mold buffer device, including the first and second hydraulic cylinders and the first and second hydraulic circuits driving them. Additionally, in... Figure 11 In the middle, to and Figure 2 The common parts of the first embodiment of the first and second hydraulic circuits shown are labeled with the same reference numerals, and their detailed descriptions are omitted.

[0264] Figure 11 The second embodiment shown connects the hydraulic circuit (first hydraulic circuit) 180 with... Figure 2 The first hydraulic circuit 140 shown in the first embodiment is different. In addition, a hydraulic circuit 112 supporting the weight including the buffer pad 110, etc., is provided between the second hydraulic cylinder 130 and the second hydraulic circuit 150.

[0265] exist Figure 11The hydraulic circuit 180 is a closed-loop hydraulic circuit comprising the following elements: a mold buffer pressure generating line 182 connected to the lower chamber 120A of the first hydraulic cylinder 120; a system pressure line 184 connected to an accumulator (first accumulator) 186 that stores the working fluid of the system pressure (first system pressure); a pilot-driven logic valve 188 whose A port is connected to the mold buffer pressure generating line 182 and whose B port is connected to the system pressure line 184; a first solenoid valve 190 that opens and closes the flow path between the mold buffer pressure generating line 182 and the system pressure line 184; a third servo motor (SM3) and a hydraulic pump (HP) that function as a pressure generator that generates pilot pressure acting on the pilot port P of the logic valve 188; and a first hydraulic line (first hydraulic line) 191 that connects the hydraulic pump (HP) to the mold buffer pressure generating line 182.

[0266] In addition, the hydraulic circuit 180 includes: a second hydraulic line (second hydraulic line) 192 connecting the upper chamber 120B of the first hydraulic cylinder 120 and the system pressure line 184 (accumulator 186); a pressure relief valve 193 disposed between the mold buffer pressure generating line 182 (first hydraulic line 191) and the system pressure line 184; a second solenoid valve 194 that selectively applies system pressure or pilot pressure to the pilot port P of the logic valve 188; an orifice 196 disposed on the first hydraulic line 191 that functions as a throttle; a pressure detector (first pressure detector) 198 that detects the pressure of the lower chamber 120A of the first hydraulic cylinder 120; and a pressure detector 199 that detects the pressure (pilot pressure) of the working oil generated by the hydraulic pump (HP).

[0267] The hydraulic circuit 180 has a structure that allows control of the mold buffer pressure corresponding to the mold buffer force during pressing by controlling the pilot pressure applied to the pilot port P of the logic valve 188. Furthermore, since the hydraulic pump (HP) is connected to the mold buffer pressure generating line 182 (lower chamber 120A of the first hydraulic cylinder 120) via the first hydraulic line 191 equipped with an orifice 196, working oil can be supplied to the lower chamber 120A of the first hydraulic cylinder 120 from the hydraulic pump (HP) before impact, and the pressure in the lower chamber 120A of the first hydraulic cylinder 120 can be pre-pressurized to a preset pressure before impact.

[0268] Figure 12 This is a block diagram illustrating a second implementation of the first controller.

[0269] like Figure 12 As shown, the controller (first controller) 200 is given a pressure signal from the pressure detector 198, indicating the pressure of the lower chamber 120A of the first hydraulic cylinder 120, and a slide position signal indicating the position of the slide 20 is given from the slide position detector 26.

[0270] The controller 200 includes a pressure command device (first pressure command device) 210, which applies a slide position signal detected by the slide position detector 26 in order to output a pressure command (including a mold buffer pressure command) corresponding to the position of the slide 20 to the pressure command device 210.

[0271] Pressure command device 210 and Figure 3 The first pressure command device 162 shown outputs a first pressure command that represents the mold buffer pressure corresponding to the mold buffer force in the pressing process, a second pressure command that pre-pressurizes the pressure of the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure before pressing, and the output timing of the first pressure command, the second pressure command, etc. is controlled based on the slide position signal.

[0272] The controller 200 calculates a torque command for driving the third servo motor (SM3) in order to control the pressure of the lower chamber 120A of the first hydraulic cylinder 120 as a pressure command, based on the pressure command output from the pressure command unit 210 and the pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the pressure detector 198.

[0273] The controller 200 outputs the torque command calculated using pressure commands, pressure signals, etc., to the third servo motor (SM3) via the amplifier 220. The third servo motor (SM3) drives the hydraulic pump (HP), causing the hydraulic pump (HP) to spray working oil at the required pressure.

[0274] When the controller 200 controls the pressure of the first hydraulic cylinder 120, it closes the first solenoid valve 190 and the second solenoid valve 194 respectively. Figure 11 (As shown in the switching position), the flow path between the mold buffer pressure generation line 182 and the system pressure line 184 is closed by the first solenoid valve 190. In addition, the pressure of the working oil (pilot pressure) adjusted by the hydraulic pump (HP) is applied to the pilot port P of the logic valve 188 via the second solenoid valve 194.

[0275] Currently, when the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to a set pressure P1 before the collision, the controller 200 calculates a torque command to drive the third servo motor (SM3) based on the pressure command (second pressure command for pre-pressurization) output from the pressure command unit 210 and a pressure signal indicating the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the pressure detector 198, and drives the third servo motor (SM3) with the calculated torque command. As a result, working oil with a pressure corresponding to the driving torque of the third servo motor (SM3) is supplied from the hydraulic pump (HP) connected to the shaft of the third servo motor (SM3) to the lower chamber 120A of the first hydraulic cylinder 120 via the first hydraulic line 191 with orifice 196 and the mold buffer pressure generation line 182, and pressure control is performed so that the pressure of the lower chamber 120A of the first hydraulic cylinder 120 becomes the set pressure P1.

[0276] Furthermore, in the pre-pressurization pressure control, the buffer pad 110 is held in the mold buffer standby position by the second hydraulic cylinder 130, which is controlled by the second hydraulic circuit 150 and the second controller 170. Therefore, even if the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized before the collision, it will not rise (i.e., pre-pressurization can be performed). In addition, since the logic valve 188 can be closed by the pressure (pilot pressure) applied from the hydraulic pump (HP) to the pilot port P of the logic valve 188 via the second solenoid valve 194 during pre-pressurization, the lower chamber 120A of the first hydraulic cylinder 120 can be pre-pressurized.

[0277] Next, we will explain the control of the mold buffer pressure during the pressing process.

[0278] If the slide reaches the collision position, the buffer pad 110 then descends along with the slide 20 (by the pressure from the slide 20).

[0279] In this case, the controller 200 calculates the torque command to drive the third servo motor (SM3) based on the pressure command output from the pressure command unit 210 (a first pressure command representing the mold buffer pressure corresponding to the mold buffer force) and the pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the pressure detector 198. The calculated torque command drives the third servo motor (SM3). As a result, the pressure (pilot pressure) applied to the pilot port P of the logic valve 188 by the hydraulic pump (HP) connected to the shaft of the third servo motor (SM3) via the second solenoid valve 194 is appropriately adjusted to control the opening and closing of the logic valve 188.

[0280] If the pilot pressure logic valve 188 is closed, the pressure in the lower chamber 120A of the first hydraulic cylinder 120 rises due to the depressurization force applied from the slide 20. If the pressure signal detected by the pressure detector 198 becomes greater than the pressure command, the controller 200 drives the third servo motor (SM3) and the hydraulic pump (HP) to reduce the pilot pressure applied to the pilot port P. The reduction in pilot pressure causes the logic valve 188 to open. If the logic valve 188 is opened, the working oil flows from the lower chamber 120A of the first hydraulic cylinder 120 through the mold buffer pressure generation line 182 and the A port to B port of the logic valve 188 to the system pressure line 184, thus reducing the pressure in the lower chamber 120A of the first hydraulic cylinder 120.

[0281] Thus, the opening and closing action of the logic valve 188 is performed by balancing the mold buffer pressure (pressure at port A of the logic valve 188) applied to the lower chamber 120A of the first hydraulic cylinder 120 and the pilot pressure (pressure at the pilot port P of the logic valve 188). The pressure on the A-port side of the working oil flowing from port A to port B of the logic valve 188, i.e., the pressure in the lower chamber 120A of the first hydraulic cylinder 120, is controlled to correspond to the pressure command. That is, the mold buffer pressure applied to the lower chamber 120A of the first hydraulic cylinder 120 is controlled by the pilot pressure applied to the pilot port P of the logic valve 188.

[0282] In addition, not only the control of the mold buffer pressure in the pressing process, the pre-pressurization in the pre-acceleration of the second hydraulic cylinder 130 can also be controlled by the pilot pressure applied to the pilot port P of the logic valve 188.

[0283] Next, if the slide position reaches the bottom dead center, the controller 200 will output a drive signal to open the first solenoid valve 190 and the second solenoid valve 194 via amplifiers 230 and 240 in order to end the control state of the mold buffer pressure.

[0284] When the first solenoid valve 190 and the second solenoid valve 194 are respectively given a drive signal, they become open, from Figure 11 The state switching valve position is shown. As a result, the first solenoid valve 190 opens, opening the flow path between the mold buffer pressure generation line 182 and the system pressure line 184. Furthermore, the second solenoid valve 194 is switched, causing the system pressure stored in the accumulator 186 to be applied to the pilot port P of the logic valve 188 via the second solenoid valve 194. Additionally, since pilot pressure is not required to be applied to the pilot port P of the logic valve 188 if the slide position reaches the bottom dead center, the third servo motor (SM3) is stopped.

[0285] When the first solenoid valve 190 is opened, the flow path between the mold buffer pressure generating pipeline 182 and the system pressure pipeline 184 is opened, the lower chamber 120A of the first hydraulic cylinder 120 is connected to the system pressure pipeline 184, and the pressure in the lower chamber 120A of the first hydraulic cylinder 120 is depressurized into system pressure.

[0286] On the other hand, if the slide reaches the bottom dead center as described above, the second hydraulic cylinder 130 will lock at the bottom dead center for a certain period of time, causing the buffer pad 110 to rise and perform position control to move to the mold buffer standby position again. However, since the lower chamber 120A of the first hydraulic cylinder 120 is connected to the system pressure line 184 via the mold buffer pressure generation line 182 and the first solenoid valve 190, and the upper chamber 120B of the first hydraulic cylinder 120 is connected to the system pressure line 184 via the second hydraulic line 192, the first hydraulic cylinder 120 will not hinder the rise of the buffer pad 110. That is, in the upper chamber 120B and lower chamber 120A of the first hydraulic cylinder 120, working oil flows freely in and out as the buffer pad 110 rises.

[0287] according to Figure 11 The hydraulic circuit (first hydraulic circuit) 180 of the second embodiment shown can supply high-pressure and high-flow-rate working oil ejected from the lower chamber 120A of the first hydraulic cylinder 120 by the logic valve 188 when the mold buffer pressure is controlled during the pressing process, thereby enabling the slide table 20 to be driven at high speed in the mold buffering process.

[0288] Furthermore, the third servo motor (SM3) and the hydraulic pump (HP) are used for small-flow control that bears the pilot pressure, thus achieving higher efficiency than... Figure 2 The first hydraulic circuit 140 of the first embodiment shown in the figure has two first hydraulic pumps / motors (P / M1-1, P / M1-2) and a first servo motor (SM1-1, SM1-2), a third servo motor (SM3) with a small capacity, and a hydraulic pump (HP), which can generate the same mold buffer pressure as the first embodiment. As a whole, the number of first hydraulic pumps / motors + first servo motors can be greatly reduced, and an inexpensive hydraulic circuit can be formed.

[0289] In addition, although the hydraulic circuit 180 of the second embodiment with logic valve 188 does not have the ability to move the buffer pad 110 upward, the buffer pad 110 can be raised by the second hydraulic cylinder 130 which controls the position of the buffer pad 110. In particular, by making the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130 smaller, the buffer pad 110 can be raised at high speed.

[0290] [other]

[0291] In this embodiment, one first hydraulic cylinder 120 for pressure control of the buffer pad 110 and one second hydraulic cylinder 130 for position control are provided, but the number of the first hydraulic cylinder 120 and the number of the second hydraulic cylinder 130 are not limited thereto.

[0292] In addition, the first hydraulic circuit 140 uses two servo motors + hydraulic pumps / motors in parallel with one first hydraulic cylinder 120, but it is not limited to this, and any number of servo motors + hydraulic pumps / motors can be set.

[0293] Similarly, the second hydraulic circuit 150 uses one servo motor + hydraulic pump / motor for one second hydraulic cylinder 130, but is not limited to this; any number of servo motors + hydraulic pumps / motors can be set. In addition, the pressure generator that generates the pilot pressure acting on the pilot port P of the logic valve 188 is not limited to using a third servo motor (SM3) + hydraulic pump (HP).

[0294] Furthermore, as Figure 11 The hydraulic circuit 180 shown is a hydraulic circuit that controls the mold buffer pressure by means of a pilot-driven logic valve 188. However, it is not limited to this hydraulic circuit 180. Any hydraulic circuit that uses a pilot-driven logic valve and controls the mold buffer pressure by controlling the pilot pressure applied to the pilot port of the logic valve can be used.

[0295] Furthermore, although the use of oil as the working fluid for the first and second hydraulic cylinders and the first and second hydraulic pumps / motors is described, it is not limited to this and water or other liquids may also be used.

[0296] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention, which is self-evident.

Claims

1. A mold buffer device, characterized in that, have: The first hydraulic cylinder supports a buffer pad, which generates a mold buffering force when the slide of the stamping machine descends. The first hydraulic circuit drives the first hydraulic cylinder; The first pressure command device outputs a first pressure command representing the mold buffer pressure corresponding to the mold buffer force; The first pressure detector detects the pressure applied to the lower chamber of the first hydraulic cylinder; A first controller controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector, such that the pressure applied to the lower chamber of the first hydraulic cylinder is the pressure corresponding to the first pressure command; The second hydraulic cylinder supports the buffer pad and allows the buffer pad to move in the vertical direction. The second hydraulic circuit drives the second hydraulic cylinder; A mold buffer position instruction device, which outputs a mold buffer position instruction indicating the position of the buffer pad; A mold buffer position detector detects the position of the buffer pad; and The second controller controls the second hydraulic circuit based on the mold buffer position command and the position of the buffer pad detected by the mold buffer position detector, so that the position of the buffer pad corresponds to the mold buffer position command. Before pressing and molding, the first pressure command device outputs a second pressure command to pre-pressurize the lower chamber of the first hydraulic cylinder to a preset pressure. Before pressing and molding, the mold buffer position command device outputs a first mold buffer position command to put the buffer pad into the mold buffer standby position. The first controller controls the first hydraulic circuit based on the second pressure command and the pressure detected by the first pressure detector, so that the pressure in the lower chamber of the first hydraulic cylinder is pre-pressurized to the pressure corresponding to the second pressure command. When the lower chamber of the first hydraulic cylinder is pre-pressurized based on the second pressure command, the second controller controls the second hydraulic circuit based on the first mold buffer position command, so that the buffer pad is in standby position at the mold buffer standby position. The first pressure command device outputs the second pressure command during the period from the moment before pressing to the moment when pressing begins.

2. The mold buffer device according to claim 1, characterized in that, The first hydraulic circuit comprises the following elements: a mold buffer pressure generating pipeline connected to the lower chamber of the first hydraulic cylinder; a system pressure pipeline connecting the upper chamber of the first hydraulic cylinder and a first accumulator for accumulating the working fluid of the first system pressure; a first hydraulic pump / motor connected between the mold buffer pressure generating pipeline and the system pressure pipeline; and a first servo motor connected to the rotating shaft of the first hydraulic pump / motor. The first controller controls the torque of the first servo motor based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector.

3. The mold buffer device according to claim 1, characterized in that, The first hydraulic circuit is a closed-loop hydraulic circuit comprising the following elements: a mold buffer pressure generating line connected to the lower chamber of the first hydraulic cylinder; a system pressure line connected to a first accumulator for accumulating working fluid for the first system pressure; a pilot-driven logic valve with port A connected to the mold buffer pressure generating line and port B connected to the system pressure line; a first solenoid valve for opening and closing the flow path between the mold buffer pressure generating line and the system pressure line; a pressure generator for generating pilot pressure acting on the pilot port of the logic valve; and a first hydraulic line connecting the pressure generator to the mold buffer pressure generating line. The first controller controls the pilot pressure based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector, thereby controlling the pressure on the A port side of the logic valve, i.e. the pressure in the lower chamber of the first hydraulic cylinder, to a pressure corresponding to the first pressure command or the second pressure command.

4. The mold buffer device according to claim 3, characterized in that, A throttle is installed on the first hydraulic line.

5. The mold buffer device according to claim 3 or 4, characterized in that, The first hydraulic circuit includes a second hydraulic line connecting the upper chamber of the first hydraulic cylinder to the system pressure line.

6. The mold buffer device according to claim 3 or 4, characterized in that, The first hydraulic circuit includes a second solenoid valve that selectively applies the first system pressure or the pilot pressure to the pilot port of the logic valve.

7. The mold buffer device according to claim 3 or 4, characterized in that, The pressure generator comprises: a hydraulic pump disposed between the system pressure line and the pilot port of the logic valve; and a third servo motor connected to the rotating shaft of the hydraulic pump. The first controller controls the torque of the third servo motor based on the first pressure command or the second pressure command and the pressure detected by the first pressure detector, thereby controlling the pilot pressure.

8. The mold buffer device according to any one of claims 1 to 4, characterized in that, The mold buffer standby position is located above the collision position at the start of the pressing and molding process. After outputting the first mold buffer position command, the mold buffer position command device outputs a second mold buffer position command to pre-accelerate the buffer pad before the slide reaches the collision position. The second controller controls the second hydraulic circuit based on the second mold buffer position command, and pre-accelerates the buffer pad during the period from the mold buffer standby position to the collision position.

9. The mold buffer device according to any one of claims 1 to 4, characterized in that, The mold buffer device includes: The second pressure command unit, whose output represents a pre-set third pressure command; and The second pressure detector detects the pressure in the lower chamber of the second hydraulic cylinder. The second controller controls the second hydraulic circuit during pressing based on the third pressure command and the pressure detected by the second pressure detector, thereby controlling the pressure in the lower chamber of the second hydraulic cylinder to the third pressure corresponding to the third pressure command.

10. The mold buffer device according to claim 9, characterized in that, The third pressure command is a pressure command corresponding to the auxiliary mold buffer force that assists the main mold buffer force generated by the first hydraulic cylinder, or a pressure command that makes the mold buffer force generated by the second hydraulic cylinder zero.

11. The mold buffer device according to any one of claims 1 to 4, characterized in that, The mold buffer position command device outputs a third mold buffer position command corresponding to the position of the slide table during the pressing and molding process. The second controller controls the second hydraulic circuit based on the third mold buffer position command during the pressing process, so that the buffer pad moves to the mold buffer position corresponding to the position of the slide.

12. The mold buffer device according to any one of claims 1 to 4, characterized in that, If the slide reaches the bottom dead center, the mold buffer position controller, after outputting the fourth mold buffer position command to hold the buffer pad in the position corresponding to the bottom dead center for a certain period of time, outputs the fifth mold buffer position command to move the buffer pad to the mold buffer standby position. If the slide reaches the bottom dead center, the second controller controls the second hydraulic circuit based on the fourth mold buffer position command and the fifth mold buffer position command. After holding the buffer pad at the position corresponding to the bottom dead center for a certain period of time, the buffer pad is moved to the mold buffer standby position.

13. The mold buffer device according to any one of claims 1 to 4, characterized in that, The second hydraulic circuit includes: a second hydraulic pump / motor connected between the upper and lower chambers of the second hydraulic cylinder; a second servo motor connected to the rotation shaft of the second hydraulic pump / motor; a second accumulator for storing working fluid under the pressure of the second system; a first pilot check valve located in the flow path between the lower chamber of the second hydraulic cylinder and the second accumulator; and a second pilot check valve located in the flow path between the upper chamber of the second hydraulic cylinder and the second accumulator. The second controller executes: When the second hydraulic pump / motor supplies working fluid to the upper chamber of the second hydraulic cylinder, the second servo motor is rotated in the first direction to supply working fluid to the upper chamber of the second hydraulic cylinder, and the working fluid discharged from the lower chamber of the second hydraulic cylinder is pressurized in the second accumulator via the first pilot check valve. When the second hydraulic pump / motor supplies working fluid to the lower chamber of the second hydraulic cylinder, the second servo motor is rotated in the second direction to supply working fluid to the lower chamber of the second hydraulic cylinder, and the working fluid discharged from the upper chamber of the second hydraulic cylinder is pressurized in the second accumulator via the second pilot check valve.

Images