Die cushion device

Abstract

The present application provides a die cushion device capable of inexpensively and favorably controlling a die cushion force. The die cushion device is provided with a first hydraulic cylinder (120) that supports a cushion pad (110) and a first hydraulic circuit (140-1) that drives the first hydraulic cylinder (120). The first hydraulic circuit (140-1) is a hydraulic closed circuit that includes a logic valve (148) connected between a die cushion cushion pressure generation line (142) and a system pressure line (144), and a hydraulic pump (HP) driven by a first servo motor (SM1) that applies a pilot pressure to the logic valve (148). A first controller controls the first servo motor (pilot pressure) based on a first pressure command corresponding to the die cushion force and a pressure detected by a first pressure detector (143), and controls the pressure of a lower chamber (120A) of the first hydraulic cylinder (120) to be the pressure indicated by the first pressure command.

Description

Technical Field

[0001] This invention relates to a die buffer device, and more particularly to a die buffer device that functions inexpensively. Background Technology

[0002] Previously, the solutions described in Patent Documents 1 and 2 were proposed as a cost-effective die buffer device.

[0003] The die buffer device described in Patent Document 1 has a hydraulic closed circuit for generating die buffer pressure connected to the lower chamber of the hydraulic cylinder supporting the buffer pad. This hydraulic closed circuit includes a die buffer pressure generating line connected to the lower chamber of the hydraulic cylinder, a system pressure line that can perform ejection function and is connected to an accumulator that stores low-pressure system oil, a pilot-operated logic valve that can act as a main safety valve during die buffering, and a pilot-operated safety valve that generates pilot pressure. The working oil is pre-pressurized and sealed in.

[0004] According to the die buffer device described in Patent Document 1, the working oil in the hydraulic closed loop can be pressurized from the buffer pad by the die buffering force applied by the hydraulic cylinder during one cycle of the buffer pad, which includes the die buffering effect and the ejection effect. This results in a simple and inexpensive device without a hydraulic pump or other hydraulic drive source.

[0005] In addition, the die buffer device described in Patent Document 2 is equipped with a hydraulic servo control function that uses a proportional valve to control the throttling element, and an electric servo control function that uses a hydraulic pump / hydraulic motor driven by a servo motor. By controlling the opening of the proportional valve and the torque of the servo motor, the die buffer pressure in the die buffer pressure generating chamber (lower chamber) of the hydraulic cylinder supporting the buffer pad becomes the pressure corresponding to the die buffer pressure command.

[0006] According to the die buffer device described in Patent Document 2, when the die buffer pressure is applied, the working oil pressed out from the lower chamber of the hydraulic cylinder is released to the low-pressure source side through a proportional valve and a hydraulic pump / hydraulic motor. As a result, compared with the case where the die buffer pressure is controlled by a servo motor (+hydraulic pump / hydraulic motor) alone, the capacity of the servo motor can be reduced. As a result, the device can be miniaturized and reduced in price.

[0007] Prior art literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-000407

[0009] Patent Document 2: International Publication No. 2010 / 058710 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The die buffer device described in Patent Document 1 is a simple and inexpensive device without a hydraulic drive source. However, the pilot-operated safety valve uses the pressure of the working oil in the lower chamber of the hydraulic cylinder to generate pilot pressure. Therefore, there is a problem that the die buffer pressure rises slowly and takes time to reach the specified pressure.

[0012] Furthermore, the die buffer device described in Patent Document 1 experiences pressure over-control due to the inherent flow characteristics of the pilot-operated safety valve, resulting in pressure fluctuations depending on the flow rate (speed of the die buffer cylinder). In stamping machinery, deceleration occurs particularly near the bottom dead center, causing a corresponding decrease in the die buffer pressure. Consequently, there is a problem that the specified pressure cannot be maintained before the bottom dead center.

[0013] On the other hand, the die buffer device described in Patent Document 2 releases the working oil pressed from the lower chamber of the hydraulic cylinder to the low-pressure source side via a hydraulic pump / hydraulic motor whose torque is controlled by a servo motor throughout the stamping process. During the period when a large amount of working oil is pressed from the lower chamber of the hydraulic cylinder (the initial period of stamping when the sliding parts of the stamping machine move quickly), the proportional valve is opened to release the working oil that cannot be handled by the hydraulic pump / hydraulic motor alone to the low-pressure source side via the proportional valve. However, when the servo motor and the proportional valve are controlled in a compact hydraulic drive device, malfunctions may occur due to mutual noise. In addition, there is a problem that the control of the servo motor and the proportional valve becomes complicated.

[0014] In addition, compared with the electric servo-type die buffer device that does not use a proportional valve, the die buffer device described in Patent Document 2 can achieve a smaller capacity of the servo motor, but it requires at least a servo motor (+ hydraulic pump / hydraulic motor) to generate the required die buffer force, which is a correspondingly expensive device.

[0015] Furthermore, while the die buffer device described in Patent Document 2 can achieve high speed or miniaturization of the servo motor in the die buffering process (lowering side), in the ejection process (rising side), since the servo valve does not hold power, the buffer pad is raised only by reversing the rotation of the hydraulic motor connected to the servo motor. Therefore, it can only provide a rising speed corresponding to the capacity and number of hydraulic motors. The more advanced the miniaturization of the servo motor, the more pronounced this phenomenon becomes.

[0016] The present invention was made in view of the following circumstances, and its object is to provide a die buffer device that can control the die buffer force inexpensively and effectively.

[0017] Technical solutions for solving technical problems

[0018] To achieve the above objectives, a first aspect of the present invention relates to a die buffer device, characterized by comprising: a first hydraulic cylinder that supports a buffer pad and causes the buffer pad to generate a die buffering force when the sliding member of the stamping machine descends; a first hydraulic circuit that drives the first hydraulic cylinder; a first pressure command device that outputs a first pressure command representing a die buffering pressure corresponding to the die buffering force; a first pressure detector that detects the pressure in the lower chamber of the first hydraulic cylinder; and a first controller that controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector, so that the pressure applied to the lower chamber of the first hydraulic cylinder becomes the pressure corresponding to the first pressure command. It is a hydraulic closed loop, which includes: a die buffer pressure generating line connected to the lower chamber of the first hydraulic cylinder; a system pressure line connected to a first accumulator that stores the working fluid of the first system pressure; a pilot-driven logic valve with its A port connected to the die buffer pressure generating line and its B port connected to the system pressure line; and a pressure generator that generates a pilot pressure acting on the pilot port of the logic valve. The first controller controls the pilot pressure based on a first pressure command and the pressure detected by a first pressure detector, controlling the pressure on the A port side of the working fluid flowing from the A port of the logic valve to the B port, i.e., the pressure in the lower chamber of the first hydraulic cylinder, to the pressure corresponding to the first pressure command.

[0019] According to the first aspect of the present invention, when the die buffer pressure is applied, the working fluid pressed out from the lower chamber of the first hydraulic cylinder is released to the low-pressure source side (first accumulator side) of the first system pressure via a pilot-driven logic valve, thereby generating the die buffer pressure. However, the pilot pressure acting on the pilot port of the logic valve, i.e. the pilot pressure generated by the pressure generator, is controlled based on the first pressure command corresponding to the die buffer force and the pressure detected by the first pressure detector, thus enabling good control of the die buffer force.

[0020] Furthermore, even when the working fluid pumped from the lower chamber of the first hydraulic cylinder is at a high flow rate during die buffering pressure, it can be handled by a logic valve, thus enabling high-speed operation of the sliding parts and making it suitable for die buffering devices that generate large die buffering forces. Moreover, since the pressure generator only needs to generate pilot pressure, it can be constructed from inexpensive components, allowing for the design of an inexpensive die buffering device.

[0021] In the die buffer device according to the second aspect of the present invention, the first hydraulic circuit has a first solenoid valve that opens and closes the flow path between the die buffer pressure generation line and the system pressure line. The first controller opens the first solenoid valve after stamping or after locking for a certain period of time after stamping, so that the working fluid stored in the first system pressure of the first accumulator can be supplied to the lower chamber of the first hydraulic cylinder.

[0022] Therefore, when the sliding member reaches the lower stop point, the die buffer pressure generated in the lower chamber of the first hydraulic cylinder (die buffer pressure generation line) can be depressurized into the first system pressure. In addition, by supplying the working fluid of the first system pressure stored in the first accumulator to the lower chamber of the first hydraulic cylinder, the piston rod of the first hydraulic cylinder rises, thereby enabling the buffer pad to rise, including the ejection action of the product.

[0023] In the die buffer device according to the third aspect of the present invention, preferably, the first hydraulic circuit has a first hydraulic line connecting the pressure generator to the die buffer pressure generation line, and a second hydraulic line connecting the upper chamber of the first hydraulic cylinder to the system pressure line. The first pressure command outputs a second pressure command to pre-pressurize the pressure of the lower chamber of the first hydraulic cylinder to a preset pressure before stamping. The first controller controls the pressure generator based on the second pressure command and the pressure detected by the first pressure detector before stamping, so that the pressure of the lower chamber of the first hydraulic cylinder is pre-pressurized to the pressure corresponding to the second pressure command.

[0024] With the buffer pad abutting against the upper limit switch and the die in the buffer standby position, working fluid corresponding to the pressure of the second pressure command is supplied from the pressure generator to the lower chamber of the first hydraulic cylinder. This pre-pressurizes the lower chamber of the first hydraulic cylinder to the pressure corresponding to the second pressure command. By pre-pressurizing the first hydraulic cylinder before stamping, forming can begin at the required die buffer pressure from the moment the sliding part of the stamping machine collides with the buffer pad.

[0025] In the die buffer device according to the fourth aspect of the present invention, it is preferable to provide a throttling element between the first hydraulic line and the pilot port of the logic valve, or between the pressure generator and the pilot port of the logic valve.

[0026] In the die buffer device according to the fifth aspect of the present invention, it is preferred that 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. When the slider reaches the lower dead center, the pressure applied to the pilot port of the logic valve is switched from the pilot pressure to the first system pressure, thereby depressurizing the die buffer pressure generated in the lower chamber of the first hydraulic cylinder into the first system pressure.

[0027] In the die buffer device according to the sixth aspect of the present invention, it is preferred that the pressure generator is configured to include a hydraulic pump disposed between the system pressure line and the pilot port of the logic valve, and a first servo motor connected to the rotating shaft of the hydraulic pump. The first controller controls the torque of the first servo motor based on the first pressure command and the pressure detected by the first pressure detector during stamping, thereby controlling the pilot pressure.

[0028] In the die buffer device according to the seventh aspect of the present invention, preferably, the pressure generator is configured to include a first hydraulic pump / hydraulic motor disposed between the system pressure line and the first hydraulic line, and a first servo motor connected to the rotating shaft of the first hydraulic pump / hydraulic motor. The first pressure command device outputs a second pressure command before stamping. The first controller controls the first servo motor based on the second pressure command and the pressure detected by the first pressure detector before stamping, so that the first hydraulic pump / hydraulic motor functions as a hydraulic pump to supply working fluid to the lower chamber of the first hydraulic cylinder, so that the pressure of the lower chamber of the first hydraulic cylinder is pre-pressurized to the pressure corresponding to the second pressure command. During stamping, the first servo motor is controlled based on the first pressure command and the pressure detected by the first pressure detector, so that the first hydraulic pump / hydraulic motor functions as a hydraulic motor, so that a portion of the working fluid pressed out from the lower chamber of the first hydraulic cylinder flows to the system pressure line via the first hydraulic pump / hydraulic motor, and the remaining working fluid pressed out from the lower chamber of the first hydraulic cylinder flows to the system pressure line via a logic valve, so that the pressure of the lower chamber of the first hydraulic cylinder is controlled to the pressure corresponding to the first pressure command.

[0029] According to the seventh aspect of the present invention, in the stamping process, a portion of the working fluid extruded from the lower chamber of the first hydraulic cylinder flows to the system pressure line via the first hydraulic pump / hydraulic motor, and the remaining working fluid extruded from the lower chamber of the first hydraulic cylinder flows to the system pressure line via a logic valve. This increases the flow rate of the working fluid extruded from the lower chamber of the first hydraulic cylinder (accelerating the speed of the sliding member) compared to the case where the fluid flows only via the logic valve. Furthermore, it reduces the heat generated by the working fluid compared to the case where the fluid flows only via the logic valve. Moreover, when the buffer pad is in the die buffer standby position, the first hydraulic pump / hydraulic motor functions as a hydraulic pump to supply working fluid to the lower chamber of the first hydraulic cylinder. This allows the buffer pad to be pressurized (pre-pressurized) before stamping, enabling forming to begin at the required pressure from the moment of impact.

[0030] In the die buffer device according to the eighth aspect of the present invention, it is preferred that the die buffer device comprises: a second hydraulic cylinder that supports the buffer pad and moves the buffer pad in a vertical direction; a second hydraulic circuit that drives the second hydraulic cylinder; a die buffer position command that outputs a die buffer position command indicating the position of the buffer pad; a die buffer position detector that detects the position of the buffer pad; and a second controller that controls the second hydraulic circuit based on the die buffer position command output from the die buffer position command and the position of the buffer pad detected by the die buffer position detector, so that the position of the buffer pad is a position corresponding to the die buffer position command.

[0031] According to the eighth aspect of the present invention, a second hydraulic cylinder controlled by position is provided independently of the first hydraulic cylinder controlled by pressure. This allows for position control of the buffer pad, enabling free control of the buffer pad's rising speed and mid-journey stopping at the die buffer standby position. For example, by controlling the buffer pad's position at the die buffer standby position, even when the lower chamber of the first hydraulic cylinder is pressurized, the buffer pad can be held in the die buffer standby position. This ensures the buffer pad is accurately positioned in the die buffer standby position, and simultaneously, the pressure in the lower chamber of the first hydraulic cylinder at the die buffer standby position can be pre-pressurized to the desired pressure, allowing forming to begin at the required forming pressure from the moment of impact.

[0032] The ninth aspect of the present invention relates to a die buffer device, comprising: a first hydraulic cylinder that supports a buffer pad and causes the buffer pad to generate a die buffering force when the sliding member of the stamping machine descends; a first hydraulic circuit that drives the first hydraulic cylinder; 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 die buffer position command that outputs a die buffer position command indicating the position of the buffer pad; a die buffer position detector that detects the position of the buffer pad; and a second controller that, based on the die buffer position command output from the die buffer position command,... The second hydraulic circuit is controlled by the position of the buffer pad detected by the die buffer position detector, so that the position of the buffer pad is corresponding to the die buffer position command. The first hydraulic circuit is a hydraulic closed circuit, which includes: a die buffer pressure generating line connected to the lower chamber of the first hydraulic cylinder; a system pressure line connected to a first accumulator that stores the working fluid of the first system pressure; a pilot-driven logic valve whose A port is connected to the die buffer pressure generating line and its B port is connected to the system pressure line; and a pilot pressure applying unit that applies pilot pressure to the pilot port of the logic valve.

[0033] According to the ninth aspect of the present invention, a first hydraulic cylinder controlled by pressure and a second hydraulic cylinder controlled by position are provided, thereby enabling independent control of the die buffering force applied to the buffer pad and the position control of the buffer pad. Even if the first hydraulic circuit driving the first hydraulic cylinder does not have the function of raising the buffer pad, the second hydraulic cylinder can move the buffer pad to the position corresponding to the die buffering position command.

[0034] Furthermore, when the first hydraulic circuit driving the first hydraulic cylinder is subjected to the die buffer pressure, the working fluid squeezed out from the lower chamber of the first hydraulic cylinder is released to the low-pressure source side through a pilot-driven logic valve, thereby generating the die buffer pressure. Therefore, it can be set as an inexpensive hydraulic circuit. On the other hand, the second hydraulic circuit driving the second hydraulic cylinder can mainly move the buffer pad during periods other than stamping and forming. Therefore, it can be set as a relatively inexpensive device. As a whole, the die buffer device can be constructed inexpensively.

[0035] In the die buffer device according to the tenth aspect of the present invention, the pilot pressure application unit is a pilot-operated safety valve disposed between the die buffer pressure generation line and the system pressure line. The set pressure of the pilot-operated safety valve is set to the desired pressure, and the pressure generated by the pilot-operated safety valve is applied to the logic valve as the pilot pressure, thereby enabling the generation of a die buffer pressure corresponding to the pilot pressure.

[0036] In the die buffer device according to the eleventh aspect of the present invention, the pilot pressure application unit is a third hydraulic line that connects the pilot port of the logic valve to the lower chamber of the second hydraulic cylinder. For example, when the auxiliary die buffer force (main die buffer force) generated by the auxiliary first hydraulic cylinder is generated from the second hydraulic cylinder, the pressure of the lower chamber of the second hydraulic cylinder can be set as the pilot pressure of the logic valve via the third hydraulic line.

[0037] In the die buffer device according to the twelfth aspect of the present invention, it is preferable that the die buffer device includes a third solenoid valve for opening and closing the flow path of the third hydraulic line. After pressurizing the third hydraulic line to the desired pressure, the third solenoid valve is closed, thereby maintaining the pilot pressure.

[0038] In the die buffer device according to the thirteenth aspect of the present invention, preferably, the die buffer position commander outputs a first die buffer position command to make the buffer pad standby position of the die buffer before stamping, and the second controller controls the second hydraulic circuit based on the first die buffer position command before stamping to make the buffer pad standby position of the die buffer.

[0039] According to the thirteenth aspect of the present invention, the buffer pad can be made to standby in the die buffer standby position based on the first die buffer position command, thus eliminating the need for an upper limit stop for making the buffer pad standby in the die buffer standby position, and allowing the die buffer standby position to be set arbitrarily. Furthermore, when a second pressure command for pre-pressurization before stamping is output from the first pressure command unit, and the first controller controls the pressure generator to pre-pressurize the pressure in the lower chamber of the first hydraulic cylinder to the pressure corresponding to the second pressure command, the buffer pad can be kept in the die buffer standby position even without an upper limit stop to prevent the buffer pad from rising, thus enabling pre-pressurization.

[0040] In the fourteenth aspect of the present invention, the die buffer standby position is preferably located above the impact position at the start of the stamping process. After outputting a first die buffer position command, the die buffer position commander outputs a second die buffer position command that pre-accelerates the buffer pad during the period from the die buffer standby position to the impact position. The second controller controls the second hydraulic circuit based on the second die buffer position command to pre-accelerate the buffer pad during the period from the die buffer standby position to the impact position. This suppresses the generation of excitation pressure (impact pressure) during impact.

[0041] In the die buffer device according to the fifteenth aspect of the present invention, it is preferred that the die buffer device 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. During stamping, a second controller 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 stamping.

[0042] In the sixteenth embodiment of the present invention, the preferred embodiment is that the third pressure command is a pressure command corresponding to the auxiliary die buffering force that assists the main die buffering force generated by the first hydraulic cylinder, or a pressure command that makes the die buffering force generated by the second hydraulic cylinder zero.

[0043] When the third pressure command is a pressure command corresponding to the auxiliary die buffering force, if the main die buffering force generated by the first hydraulic cylinder is insufficient as the desired die buffering force, the second hydraulic cylinder can generate an auxiliary die buffering force to supplement the insufficient amount. When the third pressure command is a pressure command that makes the die buffering force zero, the second hydraulic cylinder is pressure controlled so as not to hinder the main die buffering force generated by the first hydraulic cylinder.

[0044] In the die buffer device according to the seventeenth aspect of the present invention, preferably, the die buffer position commander outputs a third die buffer position command corresponding to the position of the sliding member during stamping, and the second controller controls the second hydraulic circuit based on the third die buffer position command during stamping, so that the buffer pad moves to the position corresponding to the position of the sliding member. In this case, the second hydraulic cylinder is position-controlled during stamping to avoid hindering the main die buffering force generated by the first hydraulic cylinder.

[0045] In the die buffer device according to the eighteenth aspect of the present invention, preferably, when the sliding member reaches the lower stop point, the die buffer position command device outputs a fourth die buffer position command to keep the buffer pad at the position corresponding to the lower stop point, and after outputting the fourth die buffer position command for a certain period of time, outputs a fifth die buffer position command to move the buffer pad to the die buffer standby position. When the sliding member reaches the lower stop point, the second controller controls the second hydraulic circuit based on the fourth die buffer position command and the fifth die buffer position command, so that the buffer pad is kept at the position corresponding to the lower stop point for a certain period of time, and then the buffer pad is moved to the die buffer standby position.

[0046] In the die buffer device according to the nineteenth aspect of the present invention, preferably, the second hydraulic circuit includes a second hydraulic pump / hydraulic motor connected between the upper and lower chambers of the second hydraulic cylinder, a second servo motor connected to the rotating shaft of the second hydraulic pump / hydraulic motor, a second accumulator for storing working fluid under the second system pressure, a first pilot check valve disposed in the flow path between the upper chamber of the second hydraulic cylinder and the second accumulator, and a second pilot check valve disposed in the flow path between the lower chamber of the second hydraulic cylinder and the second accumulator. The second controller controls the flow from the second hydraulic pump / hydraulic motor to the second hydraulic cylinder. When the upper chamber is supplied with working fluid, the second servo motor rotates in the first direction, supplying working fluid from the second hydraulic pump / motor to the upper chamber of the second hydraulic cylinder. Working fluid expelled from the lower chamber of the second hydraulic cylinder is also stored in the second accumulator via the second 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 rotates in the second direction, supplying working fluid from the second hydraulic pump / motor to the lower chamber of the second hydraulic cylinder. Working fluid expelled from the upper chamber of the second hydraulic cylinder is also stored in the second accumulator via the first pilot check valve. In the die buffering process, the die buffering pressure (main die buffering force) generated in the upper chamber of the first hydraulic cylinder fluctuates due to hydraulic characteristics. However, the second hydraulic cylinder can perform highly responsive electric servo pressure control, thus offsetting the pressure fluctuations of the first hydraulic cylinder.

[0047] Invention Effects

[0048] According to the present invention, when the die buffer pressure is applied, the working fluid expelled from the lower chamber of the first hydraulic cylinder is released to the low-pressure source side of the first system pressure via a pilot-driven logic valve, thereby generating the die buffer pressure. Specifically, the pilot pressure acting on the pilot port of the logic valve is controlled based on the first pressure command and the pressure of the lower chamber of the first hydraulic cylinder, thus enabling good control of the die buffer pressure (die buffer force). Furthermore, even if the working fluid expelled from the lower chamber of the first hydraulic cylinder is in a large flow rate when the die buffer pressure is applied, it can be handled by the logic valve, thus enabling high-speed operation of the sliding component and making it suitable for die buffer devices that generate large die buffer forces. Moreover, since the pressure generator only needs to generate the pilot pressure, it can be constructed from inexpensive components, allowing the die buffer device to be a cost-effective device. Attached Figure Description

[0049] Figure 1 This is a structural diagram of a stamping machine equipped with the die buffer device of the first embodiment.

[0050] Figure 2 It means to Figure 1 The diagram shows a first embodiment of a first hydraulic circuit driven by the first hydraulic cylinder of the die buffer device.

[0051] Figure 3 This is a block diagram illustrating a first embodiment of a first controller that controls the first hydraulic circuit.

[0052] Figure 4 It means to Figure 1 The figure shows a second embodiment of the first hydraulic circuit driven by the first hydraulic cylinder of the die buffer device.

[0053] Figure 5 This is a block diagram illustrating a second embodiment of a first controller that controls the first hydraulic circuit.

[0054] Figure 6 This is a structural diagram of a stamping machine equipped with the die buffer device of the second embodiment.

[0055] Figure 7 This is a diagram illustrating the first embodiment, such as the hydraulic circuit of the die buffer device applicable to the second embodiment.

[0056] Figure 8 This is a block diagram illustrating a first embodiment of a second controller that controls the second hydraulic circuit.

[0057] Figure 9 It is a waveform diagram showing the position of the sliding member, the position of the die buffer, the pressure command (set pressure), and the actual pressure during one stamping cycle when the die buffer device is controlled by the first control method.

[0058] Figure 10 It is a waveform diagram showing the position of the sliding member, the position of the die buffer, the pressure command (set pressure), and the actual pressure during a stamping cycle when the die buffer device is controlled by the second control method.

[0059] Figure 11 This is a diagram illustrating a second embodiment, such as a hydraulic circuit suitable for a die buffer device in the second embodiment.

[0060] Figure 12 This is a diagram illustrating a third embodiment, such as a hydraulic circuit suitable for the die buffer device of the second embodiment.

[0061] Explanation of reference numerals in the attached figures

[0062] 10. Stamping Machinery

[0063] 11. Cushioning Pad

[0064] 12 pillars

[0065] 14 Base

[0066] 15 Upper limit switch

[0067] 18. Guiding Department

[0068] 20 Slider

[0069] 22 Crankshaft

[0070] 24-link

[0071] 26 Slider position detector

[0072] 28 Crankshaft Encoder

[0073] 30 upper mold

[0074] 32 pad

[0075] 34 Lower mold

[0076] 100-1, 100-2 Die Buffer Device

[0077] 102 pressure ring

[0078] 104 Buffer Pin

[0079] 110 Buffer Pad

[0080] 112 Hydraulic Circuit

[0081] 112A Logic Valve

[0082] 112B Solenoid Valve

[0083] 112C Check Valve

[0084] 112D safety valve

[0085] 114 Second pressure detector

[0086] 115 Fixing part

[0087] 116 Die Buffer Position Detector

[0088] 120 First Hydraulic Cylinder

[0089] 120A Lower Room

[0090] 120B Upper Room

[0091] 120C Piston Rod

[0092] 121 Muffler

[0093] 130 Second Hydraulic Cylinder

[0094] 130A Lower Room

[0095] 130B Upper Room

[0096] 130C Piston Rod

[0097] 140, 140-1~140-5 First Hydraulic Circuit

[0098] 142 Die buffer pressure generation line

[0099] 143 First pressure detector

[0100] 144 System pressure line

[0101] 145 Pressure Detector

[0102] 146 First Accumulator

[0103] 147 Second Hydraulic Line

[0104] 148 Logic Valve

[0105] 150 First Solenoid Valve

[0106] 151 First Hydraulic Line

[0107] 152 Third Hydraulic Line

[0108] 153 Safety Valve

[0109] 154 Second Solenoid Valve

[0110] 156 throttle orifice

[0111] 157 Pilot-operated safety valve

[0112] 158 Third Solenoid Valve

[0113] 160 First Controller

[0114] 160-1 First Controller

[0115] 160-2 First Controller

[0116] 162-1 First Pressure Commander

[0117] 162-2 First Pressure Commander

[0118] 164, 166 amplifiers

[0119] 165 Amplifier / PWM Controller

[0120] 167 DC power supply device with power regeneration function

[0121] 169 AC power supply

[0122] 170 Second hydraulic circuit

[0123] Hydraulic lines 171 and 172

[0124] 173 Second accumulator

[0125] 174A First Pilot Check Valve

[0126] 174B Second Pilot Check Valve

[0127] 175A and 175B solenoid valves

[0128] Pressure detectors 176 and 177

[0129] 178A Check Valve

[0130] 178B Safety Valve

[0131] 179A and 179B connectors

[0132] 180 Second Controller

[0133] 180A Die Buffer Position Control Unit

[0134] 180B Die Buffer Pressure Control Unit

[0135] 181 Die Buffer Position Controller

[0136] 182 Die Buffer Position Commander

[0137] 183 Die Buffer Pressure Controller

[0138] 184 Second Pressure Commander

[0139] 185 Amplifier / PWM Controller

[0140] 186 DC power supply unit with power regeneration function

[0141] 187 AC power supply

[0142] 188, 189 amplifiers

[0143] SM1 First Servo Motor

[0144] SM2 Second Servo Motor

[0145] P / M1 First Hydraulic Pump / Hydraulic Motor

[0146] P / M2 Second hydraulic pump / hydraulic motor. Detailed Implementation

[0147] The preferred embodiments of the die buffer device of the present invention will be described in detail with reference to the following figures.

[0148] [First Embodiment of the Die Buffer Device]

[0149] Figure 1 This is a structural diagram of a stamping machine equipped with the die buffer device of the first embodiment.

[0150] Figure 1 The stamping machine 10 shown consists of a frame consisting of a column 12, a base 14, and a crown member (upper strength member of the frame) 16. The sliding member 20 is guided to move freely in the vertical direction by a guide part 18 provided on the column 12.

[0151] The sliding member 20 receives driving force from the servo motor via the crankshaft 22 and connecting rod 24. Figure 1 Move along the top edge in the up-down direction.

[0152] A slider position detector 26 for detecting the position of slider 20 is provided on the base 14 side of the stamping machine 10, and a crankshaft encoder 28 for detecting the angle and angular velocity of crankshaft 22 is provided on crankshaft 22.

[0153] The upper mold 30 is assembled on the sliding component 20, and the lower mold 34 is assembled on the pad 32 of the base 14.

[0154] A pressure ring (pleated pressure plate) 102 is arranged between the upper mold 30 and the lower mold 34. The lower side is supported by a buffer pad 110 via multiple buffer pins 104, and the upper side is placed (in contact) with the material.

[0155] The stamping machine 10 presses material between the upper die 30 and the lower die 34 by lowering the sliding member 20. The die buffer device 100-1 presses down on the periphery of the stamped material from below.

[0156] The die buffer device 100-1 of the first embodiment mainly consists of a pressure ring 102, a buffer pad 110 that supports the pressure ring 102 via multiple buffer pins 104, a first hydraulic cylinder 120 that supports the buffer pad 110 and generates a die buffering force on the buffer pad 110, a first hydraulic circuit 140 that drives the first hydraulic cylinder 120, and a first controller 160 that controls the first hydraulic circuit 140.

[0157] The first hydraulic cylinder 120 functions as a hydraulic cylinder that generates a punching buffer force on the buffer pad 110 through pressure control via the first hydraulic circuit 140 and the first controller 160.

[0158] <First Implementation Method of the First Hydraulic Circuit>

[0159] Figure 2 It means to Figure 1 The diagram shows a first embodiment of a first hydraulic circuit driven by the first hydraulic cylinder of the die buffer device.

[0160] 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 die buffer pressure generating line 142 of the first hydraulic circuit 140-1, and the rod side pressure chamber (hereinafter referred to as the "upper chamber") 120B of the first hydraulic cylinder 120 is open to the atmosphere through the silencer 121.

[0161] exist Figure 2 In this configuration, an upper limit stop 15 is provided on the lower surface of the base 14, allowing the buffer pad 110 to abut against it. For example... Figure 2 As shown, the buffer pad 110 abuts against the upper limit limiter 15, and the position of the buffer pad 110 is restricted. The position of the buffer pad 110 in the vertical direction (the die buffer position) is the die buffer standby position where the buffer pad 110 is in standby position before stamping.

[0162] Additionally, a die buffer position detector 116 for detecting the position of the buffer pad 110 is provided between the fixing part 115 of the first hydraulic cylinder 120 and the buffer pad 110. It should be noted that the die buffer position detector can be built into the first hydraulic cylinder 120 and detect the position of the piston rod 120C in the extension and retraction direction as the die buffer position, or it can be provided between the base 14 and the buffer pad 110.

[0163] The first hydraulic circuit 140-1 drives the first hydraulic cylinder 120 to generate a die buffering force in the buffer pad 110, and is composed of a hydraulic closed circuit. The hydraulic closed circuit includes a die buffering pressure generating line 142 connected to the lower chamber 120A of the first hydraulic cylinder 120, a system pressure line 144 connected to a first accumulator 146 that stores working oil (working fluid) under the first system pressure, a pilot-driven logic valve 148 whose A port is connected to the die buffering pressure generating line 142 and whose B port is connected to the system pressure line 144, a first solenoid valve 150 that opens and closes the flow path between the die buffering pressure generating line 142 and the system pressure line 144, and a first servo motor SM1 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 148.

[0164] Working oil is supplied from the oil supply device to the first hydraulic circuit 140-1 via a caupler (not shown) with a check valve, and the working oil is pressurized to the specified first system pressure.

[0165] The first accumulator 146, connected to the system pressure line 144, stores working oil pressurized under the first system pressure. The first accumulator 146 is set with a specified gas pressure, acting as a tank and serving as a low-pressure source. It should be noted that the low-pressure first system pressure needs to be set at least above the pressure required to raise the buffer pad 110, enabling it to eject the product and move the buffer pad 110 towards the die buffer standby position.

[0166] When the working oil under the first system pressure is sealed into the first hydraulic circuit 140, the oil supply device is disconnected from the connector. After that, the first hydraulic circuit 140-1 becomes a closed hydraulic circuit in which the working oil does not flow in or out relative to the outside. It should be noted that in the first hydraulic circuit 140-1, as long as the first system pressure is not lower than the preset lower limit value, it is not necessary to inject working oil from the oil supply device into the first hydraulic circuit 140-1.

[0167] Additionally, the first hydraulic circuit 140-1 is equipped with a first pressure detector 143 for detecting the pressure of the lower chamber 120A (die buffer pressure generation line 142) of the first hydraulic cylinder 120, a pressure detector 145 for detecting the pressure (pilot pressure) of the working oil generated by the hydraulic pump HP, a safety valve 153 disposed between the die buffer pressure generation line 142 and the system pressure line 144, and a second solenoid valve 154 that selectively applies the first system pressure or pilot pressure to the pilot port P of the logic valve 148. It should be noted that the safety valve 153 operates when abnormal pressure is generated in the lower chamber 120A of the first hydraulic cylinder 120 (when pressure control fails or a sudden abnormal pressure occurs), serving as a mechanism to prevent damage to the hydraulic equipment.

[0168] The first hydraulic circuit 140-1 has a structure that enables the generation of a die buffer pressure corresponding to the pilot pressure during the die buffering process by controlling the pilot pressure applied to the pilot port P of the logic valve 148.

[0169] <First Implementation Method of the First Controller>

[0170] Figure 3 This is a block diagram illustrating a first embodiment of a first controller controlling a first hydraulic circuit, particularly illustrating the control... Figure 2 The block diagram of the first controller 160-1 of the first embodiment of the first hydraulic circuit 140-1 shown is illustrated.

[0171] like Figure 3 As shown, a pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is applied from the first pressure detector 143 to the first controller 160-1, and a slider position signal representing the position of the slider 20 is applied from the slider position detector 26 to the first controller 160-1.

[0172] The first controller 160-1 includes a first pressure command unit 162-1, which applies a slider position signal detected by the slider position detector 26 to the first pressure command unit 162-1 in order to output a die buffer pressure command (first pressure command) corresponding to the position of the slider 20.

[0173] In order to control the die buffer force in stamping, the first pressure command 162-1 outputs a first pressure command representing the die buffer pressure corresponding to the die buffer force, and controls the timing of the output of the first pressure command based on the sliding member position signal.

[0174] Here, the die buffering force applied from the first hydraulic cylinder 120 to the buffer pad 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 hydraulic cylinder. Therefore, controlling the die buffering force means controlling the pressure in the lower chamber 120A of the first hydraulic cylinder 120.

[0175] The first controller 160-1 calculates a torque command for driving the first servo motor SM1 based on a first pressure command output from the first pressure command unit 162-1 and a pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the first pressure detector 143, so as to control the pressure of the lower chamber 120A of the first hydraulic cylinder 120 according to the first pressure command.

[0176] The first controller 160-1 outputs the torque command calculated using the first pressure command and pressure signal to the first servo motor SM1 via the amplifier 164, and drives the hydraulic pump HP with the help of the first servo motor SM1, thereby controlling the pressure (pilot pressure) of the working oil generated by the hydraulic pump HP.

[0177] In addition, when the first controller 160-1 controls the pressure of the first hydraulic cylinder 120 during the die-bearing buffer process, it sets the first solenoid valve 150 and the second solenoid valve 154 of the first hydraulic circuit 140-1 to OFF respectively. Figure 2 (Switching position shown). In the OFF state, the first solenoid valve 150 is closed, thus closing the flow path between the die buffer pressure generation line 142 and the system pressure line 144. Additionally, the second solenoid valve 154 is a four-way two-position solenoid valve, but in the OFF state, the second solenoid valve 154 selects the pilot pressure from the two input pressures (pilot pressure and first system pressure) and applies it to the pilot port P of the logic valve 148.

[0178] The logic valve 148, which applies pilot pressure to the pilot port P, is closed as long as no pressure exceeding the pilot pressure is applied to the A port side of the logic valve 148 via the die buffer pressure generation line 142, and can pressurize the lower chamber 120A of the first hydraulic cylinder 120.

[0179] Here, when the sliding member 20 of the stamping machine 10 descends and the sliding member position reaches the impact position (the die buffer standby position), the buffer pad 110 then descends together with the sliding member 20 (by the downward pressure from the sliding member 20).

[0180] The piston rod 120C of the first hydraulic cylinder 120 descends together with the buffer pad 110, and the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is compressed, causing the pressure in the lower chamber 120A to rise.

[0181] A die buffer pressure proportional to the die buffer force is generated in the lower chamber 120A of the first hydraulic cylinder 120. The following forces are applied to the poppet of the logic valve 148: a force to open the poppet caused by the die buffer pressure acting on the die buffer pressure generation line 142 from port A and the first system pressure acting on the system pressure line 144 from port B; a force to close the poppet caused by the pilot pressure from the pilot port P and the spring force inside the logic valve; and a fluid force acting in the direction that prevents pressurized oil from flowing from the die buffer pressure generation line 142 to the system pressure line 144 (closing the poppet).

[0182] Here, the condition that the die buffer pressure is slightly greater than the pilot pressure and the pilot pressure is much greater than the first system pressure (the difference between the pilot pressure and the system pressure is greater than the difference between the die buffer pressure and the pilot pressure) becomes the condition under which the pilot pressure controls the die buffer pressure.

[0183] In the die buffering process, to maintain the balance of these forces, the position (opening) of the lifting head of the logic valve 148 is adjusted, generating die buffering pressure in this series of actions. The first controller 160-1 controls the pilot pressure generated by the hydraulic pump HP based on a first pressure command indicating the desired die buffering pressure, thereby generating the die buffering pressure indicated by the first pressure command.

[0184] When the slider reaches the lower stop point, the first controller 160-1 outputs a drive signal that turns the second solenoid valve 154 ON via amplifier 168 to end the control state of the die buffer pressure.

[0185] Therefore, a first system pressure is applied to the pilot port P of logic valve 148 via the second solenoid valve 154, causing the lifting head of logic valve 148 to move in the opening direction, and the die buffer pressure is released. At the point when the release of pressure in the lower chamber 120A of the first hydraulic cylinder 120 is complete, the lifting head of logic valve 148 closes. It should be noted that when the slider reaches the lower dead center, it is not necessary to apply pilot pressure to the pilot port P of logic valve 148; therefore, it is preferable to stop the first servo motor SM1.

[0186] After the lower chamber 120A of the first hydraulic cylinder 120 is depressurized, when the slider 20 rises from the lower dead center, the downward pressure from the slider 20 is no longer applied to the buffer pad 110. The pressure of the working oil (depressurized working oil) in the lower chamber 120A of the first hydraulic cylinder 120 is released, and the buffer pad 110 rises slightly. However, afterwards, the connection between the die buffer pressure generation line 142 and the system pressure line 144 is cut off by the logic valve 148 and the first solenoid valve 150, so the buffer pad 110 can stop (lock) near the lower dead center.

[0187] After a certain period of locking, the first controller 160-1 outputs a drive signal to the first solenoid valve 150 via the amplifier 166, which turns the first solenoid valve 150 ON.

[0188] When a drive signal is applied, the first solenoid valve 150 becomes ON, and the valve position changes from... Figure 2 The valve opens when the state is switched as shown. As a result, the flow path between the die buffer pressure generation line 142 and the system pressure line 144 is opened, and the working oil stored in the first accumulator 146 at the first system pressure can be supplied to the lower chamber 120A of the first hydraulic cylinder 120 via the system pressure line 144, the first solenoid valve 150 and the die buffer pressure generation line 142.

[0189] The first system pressure has the pressure to raise the buffer pad 110, to perform the ejection function of the product, and to move the buffer pad 110 to the die buffer standby position. Therefore, the working oil through the first system pressure flows into the lower chamber 120A of the first hydraulic cylinder 120, causing the piston rod 120C (buffer pad 110) of the first hydraulic cylinder 120 to rise.

[0190] The buffer pad 110 rises to abut against the upper limit stop 15 and stops there (standby).

[0191] According to the die buffer device having a first hydraulic circuit 140-1 and a first controller 160-1, when the die buffer pressure is applied, the working oil squeezed out from the lower chamber 120A of the first hydraulic cylinder 120 is released to the low-pressure source side of the first system pressure through the pilot-driven logic valve 148, thereby enabling the die buffer pressure to be generated. In particular, the first servo motor SM1 and the hydraulic pump HP are servo controlled based on the first pressure command and the pressure of the lower chamber 120A of the first hydraulic cylinder 120, thereby generating the pilot pressure acting on the pilot port P of the logic valve 148, thus enabling good control of the die buffer pressure (die buffer force).

[0192] That is, compared with the die buffer device described in Patent Document 1, which generates pilot pressure through a pilot-operated safety valve, the die buffer device with a first hydraulic circuit 140-1 and a first controller 160-1 has better responsiveness in controlling the pilot pressure and can shorten the time until the die buffer pressure reaches the specified pressure (accelerate the increase of the die buffer pressure).

[0193] Furthermore, in the hybrid servo die buffer device described in Patent Document 2, which separately servo controls the proportional valve and the hydraulic pump / motor, the hydraulic pump / motor, acting as a pressure generator, directly bears the large flow rate of the die buffer cylinder, resulting in significant interference. In contrast, the first hydraulic circuit 140-1 has a hydraulic pump HP that functions as a pressure generator in the pilot pressure line with no flow (low flow), thus minimizing interference. In other words, the hybrid servo die buffer device described in Patent Document 2 controls the pressure line of the high-flow die buffer cylinder, while the hydraulic pump HP of the first hydraulic circuit 140-1 controls the pilot pressure, which is unaffected by the die buffer flow rate, resulting in less interference and better control.

[0194] Furthermore, even when the working oil pumped from the lower chamber 120A of the first hydraulic cylinder 120 is at a high flow rate during die buffering pressure, the flow rate can be handled by the logic valve 148. Therefore, high-speed sliding component operation can be achieved, making it suitable for die buffering devices that generate large die buffering forces. Moreover, the hydraulic pump HP and servo motor SM, which function as pressure generators to generate pilot pressure, only need to generate pilot pressure, so a large flow rate is not required. Therefore, it can be constructed with inexpensive (small capacity, few units), and the overall space-saving design of the die buffering device can be achieved while maintaining its low cost.

[0195] <Second Implementation Method of the First Hydraulic Circuit>

[0196] Figure 4 It means to Figure 1 The diagram shows a second embodiment of the first hydraulic circuit driven by the first hydraulic cylinder of the die buffer device. It should be noted that, in... Figure 4 In the middle, to and Figure 2 The common parts of the first hydraulic circuit 140-1 in the first embodiment shown are labeled with the same reference numerals, and their detailed descriptions are omitted.

[0197] Figure 4 The first hydraulic circuit 140-2 shown replaces Figure 2 The first hydraulic circuit 140-1 shown is equipped with a first hydraulic pump / motor (first hydraulic pump / motor) P / M1, which is connected to the first hydraulic pump / motor P / M1 and the die buffer pressure generation line 142. It also has a first hydraulic line (first hydraulic line) 151 connecting the first hydraulic pump / motor P / M1 to the die buffer pressure generation line 142, and a second hydraulic line (second hydraulic line) 147 connecting the upper chamber 120B of the first hydraulic cylinder 120 to the system pressure line 144. Furthermore, a throttling orifice 156, functioning as a throttling element, is provided between the first hydraulic pump / motor P / M1 and the second solenoid valve 154.

[0198] The first hydraulic circuit 140-2 can supply working oil from the first hydraulic pump / hydraulic motor P / M1 to the lower chamber 120A of the first hydraulic cylinder 120 via the first hydraulic line 151 and the die buffer pressure generation line 142. In addition, it has a structure that can generate die buffer pressure in the die buffering process by using the first hydraulic pump / hydraulic motor P / M1 and the logic valve 148.

[0199] <Second Implementation of the First Controller>

[0200] Figure 5 This is a block diagram illustrating a second embodiment of a first controller controlling a first hydraulic circuit, particularly illustrating the control... Figure 4The diagram shows the block diagram of the first controller 160-2 of the first hydraulic circuit 140-2. It should be noted that... Figure 5 In the middle, to and Figure 3 The common parts of the first controller 160-1 shown are labeled with the same reference numerals, and their detailed descriptions are omitted.

[0201] Figure 5 The first controller 160-2 shown has a first pressure command unit 162-2, which applies a slider position signal detected by the slider position detector 26 to the first pressure command unit 162-2 in order to output a die buffer pressure command (first pressure command, second pressure command) corresponding to the position of the slider 20.

[0202] In addition to outputting a first pressure command indicating the die buffer pressure, the first pressure command 162-2 also outputs a second pressure command to pre-pressurize the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure before stamping. At this point, it is consistent with... Figure 3 The first pressure command device 162-1 shown is different.

[0203] In addition, in order to pre-pressurize the lower chamber 120A of the first hydraulic cylinder 120 before stamping, the first controller 160-2 calculates the torque command for driving the first servo motor SM1. In order to generate the desired die buffer pressure in the lower chamber 120A of the first hydraulic cylinder 120 during stamping, the first controller 160-2 calculates the torque command for driving the first servo motor SM1 and drives and controls the first servo motor SM1 based on the calculated torque command.

[0204] When the first controller 160-2 generates pressure (pre-pressurization, die buffer pressure) in the lower chamber 120A of the first hydraulic cylinder 120, it sets the first solenoid valve 150 and the second solenoid valve 154 of the first hydraulic circuit 140-2 to OFF. Figure 4 (Switching position shown). In the OFF state, the first solenoid valve 150 is closed, thus closing the flow path between the die buffer pressure generation line 142 and the system pressure line 144. Additionally, the second solenoid valve 154 is a four-way two-position solenoid valve, but in the OFF state, the second solenoid valve 154 selects the pilot pressure from the two input pressures (pilot pressure and first system pressure) and applies it to the pilot port P of the logic valve 148.

[0205] Here, as Figure 4As shown, the buffer pad 110 is held in the die buffer standby position. Before the sliding member position reaches the impact position (die buffer standby position), the first pressure command 162-2 outputs a second pressure command to pre-pressurize the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure (in this example, the second pressure command is the same pressure command as the first pressure command that represents the die buffer pressure corresponding to the die buffer force in the stamping process).

[0206] The first controller 160-2 calculates a torque command for driving the first servo motor SM1 based on a second pressure command for pre-pressurization output from the first pressure command unit 162-2 and a pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the first pressure detector 143, so as to control the pressure of the lower chamber 120A of the first hydraulic cylinder 120 according to the second pressure command. When calculating the torque command, the angular velocity of the drive shaft of the first servo motor SM1 is preferably used as the angular velocity feedback signal to ensure dynamic stability.

[0207] The first controller 160-2 outputs the torque command calculated using the second pressure command and pressure signal to the first servo motor SM1 via the amplifier and PWM controller (PWM: Pulse Width Modulation) 165, and drives the first hydraulic pump / hydraulic motor P / M1 as a hydraulic pump through the first servo motor SM1, so that the working oil is supplied from the first hydraulic pump / hydraulic motor P / M1 to the lower chamber 120A of the first hydraulic cylinder 120.

[0208] In order to prevent the buffer pad 110 from rising when it abuts against the upper limit switch 15, the pressure in the lower chamber 120A of the first hydraulic cylinder 120 is pressurized (pre-pressurized) to the pressure indicated by the second pressure command through the supply of working oil.

[0209] Next, when the sliding member 20 of the stamping machine 10 descends and the sliding member position reaches the impact position (the die buffer standby position), the buffer pad 110 then descends together with the sliding member 20 (by the downward pressure from the sliding member 20).

[0210] The piston rod 120C of the first hydraulic cylinder 120 descends together with the buffer pad 110, and the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is forced out. A portion of the working oil forced out from the lower chamber 120A of the first hydraulic cylinder 120 flows to the system pressure line 144 via the die buffer pressure generation line 142, the first hydraulic line 151, and the first hydraulic pump / hydraulic motor P / M1. In addition, the remaining working oil forced out from the lower chamber 120A of the first hydraulic cylinder 120 flows to the system pressure line 144 via the die buffer pressure generation line 142 and the logic valve 148.

[0211] Here, the first controller 160-2 calculates a torque command for driving the first servo motor SM1 based on a first pressure command representing the die buffer pressure and a pressure signal representing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 detected by the first pressure detector 143, so as to control the pressure of the lower chamber 120A of the first hydraulic cylinder 120 according to the first pressure command. When calculating the torque command, the angular velocity of the drive shafts of the first servo motors SM1-1 and SM1-2 is preferably used as the angular velocity feedback signal to ensure dynamic stability.

[0212] The first controller 160-2 outputs the torque command calculated using pressure commands and pressure signals to the first servo motor SM1 via an amplifier and PWM controller 165, thereby controlling the pressure of the lower chamber 120A of the first hydraulic cylinder 120.

[0213] However, during pressure control when the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized, the torque output direction of the first servo motor SM1 is opposite to the torque output direction of the first servo motor SM1 during the descent of the slider 20 until it reaches the lower stop point after impacting the buffer pad 110 (the upper die 30 assembled on the slider 20 collides with the material, the pressure ring 102, and the buffer pad 110 supported by the first hydraulic cylinder 120 via the buffer pin 104).

[0214] That is, under the action of the power received by the buffer pad 110 from the sliding member 20, the working oil pressed out from the lower chamber 120A of the first hydraulic cylinder 120 flows into the first hydraulic pump / hydraulic motor P / M1, and the first hydraulic pump / hydraulic motor P / M1 functions as a hydraulic motor. Under the action of the first hydraulic pump / hydraulic motor P / M1, the first servo motor SM1 is driven and functions as a generator.

[0215] In other words, the force transmitted from the sliding member 20 to the first hydraulic cylinder 120 via the buffer pad 110 compresses the lower chamber 120A of the first hydraulic cylinder 120, generating the die buffer pressure. Simultaneously, under the action of the die buffer pressure, the first hydraulic pump / motor P / M1 functions as a hydraulic motor. The rotational shaft torque generated by the first hydraulic pump / motor P / M1 resists the driving torque of the first servo motor SM1, causing the first servo motor SM1 to rotate and controlling the die buffer pressure.

[0216] In the generation of the die buffer pressure, the power generated by the first servo motor SM1 is regenerated in the AC power supply 169 via the amplifier and PWM controller 165 and the DC power supply device 167 with power regeneration function.

[0217] Additionally, the pilot port P of the logic valve 148 is pressured on the inflow side of the first hydraulic pump / hydraulic motor P / M1 via the throttle orifice 156 and the second solenoid valve 154 as pilot pressure. However, the remaining working oil in the working oil pumped out from the lower chamber 120A of the first hydraulic cylinder 120, which could not be processed at the first hydraulic pump / hydraulic motor P / M1, flows from port A of the logic valve 148, which is connected to the die buffer pressure generation line 142, to the low-pressure system pressure line 144.

[0218] After stamping, the first controller 160-2 and Figure 3 The first controller 160-1 shown can also control the first hydraulic circuit 140-2.

[0219] According to the die buffer device having a first hydraulic circuit 140-2 and a first controller 160-2, such as Figure 4 As shown, when the buffer pad 110 is in the standby position of the die buffer standby position abutting against the upper limit switch 15, working oil can be supplied from the first hydraulic pump / hydraulic motor P / M1 to the lower chamber 120A of the first hydraulic cylinder 120 via the first hydraulic line 151 and the die buffer pressure generating line 142. Thus, the lower chamber 120A of the first hydraulic cylinder 120 can be pressurized (pre-pressurized) before stamping.

[0220] Additionally, when the buffer pad 110 descends together with the sliding member 20 during stamping, working oil is forced out from the lower chamber 120A of the first hydraulic cylinder 120. A portion of the working oil forced out from the lower chamber 120A of the first hydraulic cylinder 120 flows to the system pressure line 144 via the die buffer pressure generation line 142, the first hydraulic line 151, and the first hydraulic pump / hydraulic motor P / M1. The remaining working oil forced out from the lower chamber 120A of the first hydraulic cylinder 120 flows to the system pressure line 144 via the die buffer pressure generation line 142 and the logic valve 148. It should be noted that, along with the descent of the buffer pad 110, working oil under system pressure is supplied from the system pressure line 144 to the upper chamber 120B of the first hydraulic cylinder 120 via the second hydraulic line 147.

[0221] A portion of the working oil pumped from the lower chamber 120A of the first hydraulic cylinder 120 is discharged via the first hydraulic pump / motor P / M1, enabling the first hydraulic pump / motor P / M1 to function as a hydraulic motor (load). This allows the first hydraulic pump / motor P / M1 and the first servo motor SM1 to absorb a portion of the die-bearing force generated by the buffer pad 110. Furthermore, the remaining working oil pumped from the lower chamber 120A of the first hydraulic cylinder 120 is discharged via a logic valve 148, which functions as a throttling device. This allows the logic valve 148 to absorb a portion of the die-bearing force generated by the buffer pad 110. Additionally, the logic valve 148 can handle a large flow rate of working oil, thus enabling the first servo motor SM1, which drives the first hydraulic pump / motor P / M1, to have a smaller capacity.

[0222] Furthermore, by rotating the first servo motor SM1 in the direction that feeds working oil into the lower chamber 120A of the first hydraulic cylinder 120, the lifting speed can be freely controlled during the ejection process. Applying torque to the first servo motor SM1 during this process increases the pressure in the lower chamber 120A of the first hydraulic cylinder 120. As a result, a greater ejection force can be generated compared to obtaining an ejection force dependent on the pressure of the first accumulator 146.

[0223] [Second Embodiment of the Die Buffer Device]

[0224] Figure 6 This is a structural diagram of a stamping machine equipped with the die buffer device of the second embodiment. It should be noted that... Figure 6 In the middle, to and Figure 1 The common parts of the die buffer device in the first embodiment shown are labeled with the same reference numerals, and their detailed descriptions are omitted.

[0225] Figure 6 The die buffer device 100-2 of the second embodiment shown includes, in addition to the first hydraulic cylinder 120, a second hydraulic cylinder 130 that supports the buffer pad 110 and moves the buffer pad 110 in the vertical direction. It also includes a second hydraulic circuit 170 for driving the second hydraulic cylinder 130 and a second controller 180 for controlling the second hydraulic circuit 170. At this point, it is similar to... Figure 1 The die buffer device 100-1 shown is different.

[0226] Figure 6 The piston rod 120C of the second hydraulic cylinder 130 shown is connected to the lower surface of the buffer pad 110.

[0227] In this example, the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130 is preferably larger than the cross-sectional area of ​​the lower chamber 120A of the first hydraulic cylinder 120, and the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130 is preferably smaller than the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130.

[0228] As will be described later, 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 remain low even if the downward load (= the reaction force of the upward load generated by pre-pressurization) is increased. When the pressure in the upper chamber 130B is low, the depressurization of the upper chamber 130B during impact can be accelerated. (This is because the time it takes for the pressure to decrease from the amount of reaction force to the system pressure is negligible.) As a result, the prescribed buffering force brought by the lower chamber 120A of the first hydraulic cylinder 120 can be generated immediately after the impact. In addition, 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) relative to the amount of working oil supplied to the lower chamber 130A of the second hydraulic cylinder 130 can be accelerated.

[0229] [First Embodiment, such as the hydraulic circuit for the die buffer device of the second embodiment]

[0230] Figure 7 This is a diagram showing the first embodiment, such as the hydraulic circuit of the die buffer device applicable to the second embodiment, and in particular, the diagram showing the first hydraulic circuit 140-3 and the second hydraulic circuit 170.

[0231] exist Figure 7 In the first hydraulic circuit 140-3 shown, for the... Figure 4 The common parts of the first hydraulic circuit 140-2 shown are labeled with the same reference numerals, and their detailed descriptions are omitted.

[0232] Figure 7 The first hydraulic circuit 140-3 shown is... Figure 4 Compared to the first hydraulic circuit 140-2 shown, a hydraulic pump HP is provided instead of the first hydraulic pump / hydraulic motor P / M1. In addition, a throttling orifice 156 is provided in the first hydraulic line 151 to function as a throttling element, which is different.

[0233] The first hydraulic circuit 140-3 and Figure 2 The first hydraulic circuit 140-1 shown also has the following structure, in which the pilot pressure applied to the pilot port P of the logic valve 148 is controlled by the hydraulic pump HP driven by the first servo motor SM1, and the corresponding die buffer pressure can be generated in the die buffering process.

[0234] Furthermore, the first hydraulic circuit 140-3 has, for example, a structure in which, when the buffer pad 110 is held in the die buffer standby position and does not move, the first solenoid valve 150 and the second solenoid valve 154 are respectively set to OFF, and the hydraulic pump HP is driven by the first servo motor SM1. This allows the lower chamber 120A of the first hydraulic cylinder 120 to be pressurized (pre-pressurized) via the first hydraulic line 151 equipped with a throttle orifice 156 and the die buffer pressure generation line 142. It should be noted that, during the pre-pressurization of the lower chamber 120A of the first hydraulic cylinder 120, a pilot pressure equivalent to the pre-pressurization pressure is applied from the hydraulic pump HP to the pilot port P of the logic valve 148. The logic valve 148 closes, therefore the working oil in the lower chamber 120A of the first hydraulic cylinder 120 does not flow to the system pressure line 144 via the logic valve 148.

[0235] According to the die buffer device having the first hydraulic circuit 140-3, and having Figure 2 Similarly, the die buffer device of the first hydraulic circuit 140-1 shown also releases the working oil squeezed from the lower chamber 120A of the first hydraulic cylinder 120 to the low-pressure source side of the first system pressure via the pilot-driven logic valve 148 when the die buffer pressure is applied. This enables the die buffer pressure to be generated. In particular, based on the first pressure command and the pressure of the lower chamber 120A of the first hydraulic cylinder 120, the first servo motor SM1 and the hydraulic pump HP are used to servo control the pilot pressure acting on the pilot port P of the logic valve 148, thereby enabling good control of the die buffer pressure (die buffer force).

[0236] That is, compared with the die buffer device described in Patent Document 1, which generates pilot pressure by a pilot-operated safety valve, the die buffer device with the first hydraulic circuit 140-3 has better responsiveness in controlling the pilot pressure and can shorten the time until the die buffer pressure reaches the specified pressure (accelerate the increase of the die buffer pressure).

[0237] Furthermore, in the hybrid servo die buffer device described in Patent Document 2, which separately servo controls the proportional valve and the hydraulic pump / motor, the hydraulic pump / motor, acting as a pressure generator, directly bears the large flow rate from the die buffer cylinder, resulting in significant interference. In contrast, the first hydraulic circuit 140-3 has a hydraulic pump HP functioning as a pressure generator on the pilot pressure line with no flow (low flow), thus experiencing less interference. In other words, the hybrid servo die buffer device described in Patent Document 2 controls the pressure of the high-flow die buffer cylinder pressure line. In contrast, the hydraulic pump HP of the first hydraulic circuit 140-3 is connected to the die buffer pressure generation line 142 via the throttle orifice 156, thus enabling control of the pilot pressure, which is almost unaffected by the flow rate expelled from the lower chamber 120A of the first hydraulic cylinder 120. Therefore, the first hydraulic circuit 140-3 experiences less interference and can be well controlled.

[0238] On the other hand, the first hydraulic circuit 140-3 cannot direct the working oil that moves the first hydraulic cylinder 120 to the first hydraulic cylinder 120, and cannot make the buffer pad 110 move in the up and down direction.

[0239] <Second Hydraulic Circuit>

[0240] The second hydraulic circuit 170 has a structure in which the buffer pad 110 can be moved in the vertical direction, the second hydraulic cylinder 130 can be driven to hold it in a desired position, and the pressure of the second hydraulic cylinder 130 can be controlled.

[0241] The piston rod 130C of the second hydraulic cylinder 130 is connected to the lower surface of the buffer pad 110 in the same way as the first hydraulic cylinder 120. The lower chamber 130A of the second hydraulic cylinder 130 is connected to the hydraulic line 171 of the second hydraulic circuit 170 via the hydraulic circuit 112 which has the function of preventing it from falling due to its own weight, and the upper chamber 130B of the second hydraulic cylinder 130 is connected to the hydraulic line 172 of the second hydraulic circuit 170 via the hydraulic circuit 112.

[0242] When working oil is supplied from one hydraulic line to the second hydraulic cylinder 130, the other hydraulic line is switched to a low-pressure second system pressure as described later. When working oil is supplied from the other hydraulic line to the second hydraulic cylinder 130, one hydraulic line is switched to the second system pressure.

[0243] The hydraulic circuit 112, which has the function of preventing itself from falling, has the function of supporting the weight including the buffer pad 110, and has 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 safety valve 112D, and a second pressure detector 114.

[0244] The pressure of the lower chamber 130A (or hydraulic line 171) of the second hydraulic cylinder 130 or the pressure of the upper chamber 130B (hydraulic line 172) of the second hydraulic cylinder 130 is applied to the pilot port of the logic valve 112A by the ON / OFF state of the solenoid valve 112B.

[0245] When the solenoid valve 112B is OFF without operating the stamping machine 10 (die buffer device) Figure 7 In the current state, pressure (a pressure equivalent to the weight of the pressure on the hydraulic line 171) is applied to the pilot port P of the logic valve 112A to the lower chamber 130A of the second hydraulic cylinder 130, and the logic valve 112A closes. As a result, the working oil in the lower chamber 130A of the second hydraulic cylinder 130 does not flow out, and the second hydraulic cylinder 130 is able to support the weight of the buffer pad 110, etc.

[0246] On the other hand, when working oil is supplied to the lower chamber 130A of the second hydraulic cylinder 130 to raise the buffer pad 110, the solenoid valve 112B is turned ON. It should be noted that when the buffer pad 110 is raised, working oil with a pressure higher than the second system pressure is supplied to the hydraulic line 171 as described later, and the hydraulic line 172 is depressurized to the second system pressure.

[0247] When solenoid valve 112B is ON, a second system pressure is applied to the upper chamber 130B (hydraulic line 172) of the second hydraulic cylinder 130 via the pilot port P of logic valve 112A. This second system pressure is lower than the pressure on hydraulic line 171 when working oil is supplied to the lower chamber 130A of the second hydraulic cylinder 130, thus opening logic valve 112A. As a result, working oil can be supplied from hydraulic line 171 to the lower chamber 130A of the second hydraulic cylinder 130 via logic valve 112A, and the working oil expelled from the upper chamber 130B of the second hydraulic cylinder 130 flows to the hydraulic line 172, which carries the second system pressure.

[0248] Additionally, when supplying working oil to the upper chamber 130B of the second hydraulic cylinder 130 to lower the buffer pad 110, the solenoid valve 112B is turned off. It should be noted that when lowering the buffer pad 110, working oil with a pressure higher than the second system pressure is supplied to the hydraulic line 172 as described later, and the hydraulic line 171 is depressurized to the second system pressure.

[0249] When solenoid valve 112B is OFF, a second system pressure is applied to the lower chamber 130A (hydraulic line 171) of the second hydraulic cylinder 130 via the pilot port P of logic valve 112A. This second system pressure is lower than the pressure on hydraulic line 171 when working oil is supplied to the upper chamber 130B of the second hydraulic cylinder 130, thus opening logic valve 112A. As a result, working oil can be supplied from hydraulic line 172 to the upper chamber 130B of the second hydraulic cylinder 130, and the working oil expelled from the lower chamber 130A of the second hydraulic cylinder 130 flows through logic valve 112A to the hydraulic line 171 with the second system pressure.

[0250] It should be noted that the second pressure detector 114 detects the pressure in the lower chamber 130A of the second hydraulic cylinder 130. Furthermore, the hydraulic circuit 112, which has a function to prevent it from falling due to its own weight, is not a necessary component of the die buffer device of the second embodiment.

[0251] The second hydraulic circuit 170 mainly includes a second hydraulic pump / motor (second hydraulic pump / motor) P / M2 connected between hydraulic lines 171 and 172, a second servo motor SM2 connected to the rotating shaft of the second hydraulic pump / motor P / M2, a second accumulator 173 that stores working oil under the second system pressure, a first pilot check valve 174A located in the flow path between the lower chamber 130A of the second hydraulic cylinder 130 and the second accumulator 173, a second pilot check valve 174B located in the flow path between the upper chamber 130B of the second hydraulic cylinder 130 and the second accumulator 173, solenoid valves 175A and 175B for applying pilot pressure to open the first pilot check valve 174A and the second pilot check valve 174B respectively, and pressure detectors 176 and 177 for detecting the pressure of hydraulic lines 171 and 172 respectively.

[0252] In addition, a pair of check valves 178A are installed between the hydraulic lines 171 and 172, and a safety valve 178B is installed between the check valve 178A and the second accumulator 173 to prevent abnormal pressure.

[0253] The second hydraulic circuit 170 supplies working oil to the oil supply device not shown in the figure through the joints 179A and 179B with check valves connected to the hydraulic lines 171 and 172, and seals the working oil at the specified second system pressure.

[0254] The working oil of the second system pressure is stored in the second accumulator 173, which is connected to the hydraulic lines 171 and 172 respectively via the first pilot check valve 174A and the second pilot check valve 174B. The second system pressure is preferably set to a pressure in the range of 0.1MPa to 1.0MPa.

[0255] The second hydraulic pump / hydraulic motor P / M2 can discharge working oil from two ports, with one port of the second hydraulic pump / hydraulic motor P / M2 connected to hydraulic line 171 and the other port connected to hydraulic line 172.

[0256] Figure 7 Solenoid valves 175A and 175B shown are both in the OFF state. However, when the buffer pad 110 is raised, solenoid valve 175A is ON and solenoid valve 175B is OFF. On the other hand, when the buffer pad 110 is lowered, solenoid valve 175A is OFF and solenoid valve 175B is ON.

[0257] In addition, when the second servo motor SM2 raises the buffer pad 110, it drives the second hydraulic pump / hydraulic motor P / M2 to supply pressurized oil from one port of the second hydraulic pump / hydraulic motor P / M2 via the hydraulic line 171 and the hydraulic circuit 112 to the lower chamber 130A of the second hydraulic cylinder 130. When the buffer pad 110 lowers, it drives the second hydraulic pump / hydraulic motor P / M2 to supply pressurized oil from the other port of the second hydraulic pump / hydraulic motor P / M2 via the hydraulic line 172 and the hydraulic circuit 112 to the upper chamber 130B of the second hydraulic cylinder 130.

[0258] When the buffer pad 110 is raised (pressurizing the lower chamber 130A of the second hydraulic cylinder 130), the second hydraulic pump / hydraulic motor P / M2 is driven to supply pressurized oil to the lower chamber 130A of the second hydraulic cylinder 130. In this case, the solenoid valve 175A is ON, and the second system pressure stored in the second accumulator 173 is applied to the first pilot check valve 174A via the solenoid valve 175A. Therefore, the first pilot check valve 174A remains closed.

[0259] On the other hand, when the solenoid valve 175B is OFF, the pressure of the hydraulic line 171 (lower chamber 130A of the second hydraulic cylinder 130) is applied to the second pilot check valve 174B via the solenoid valve 175B. Therefore, the second pilot check valve 174B is open, and the pressure of the upper chamber 130B of the second hydraulic cylinder 130 is depressurized to the second system pressure.

[0260] Thus, the working oil discharged from one port of the second hydraulic pump / hydraulic motor P / M2 is supplied to the lower chamber 130A of the second hydraulic cylinder 130 via the hydraulic line 171 and the hydraulic circuit 112. As the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130 rises, the working oil squeezed out from the upper chamber 130B of the second hydraulic cylinder 130 flows into the other port of the second hydraulic pump / hydraulic motor P / M2 via the hydraulic line 172, and is stored in the second accumulator 173 via the second pilot check valve 174B.

[0261] In addition, when the buffer pad 110 is lowered (when the upper chamber 130B of the second hydraulic cylinder 130 is pressurized), the second hydraulic pump / hydraulic 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 175B is ON, and the second system pressure stored in the second accumulator 173 is applied to the second pilot check valve 174B via the solenoid valve 175B. Therefore, the second pilot check valve 174B remains closed.

[0262] On the other hand, when solenoid valve 175A is OFF, the pressure of hydraulic line 172 (upper chamber 130B of the second hydraulic cylinder 130) is applied to the first pilot check valve 174A via solenoid valve 175A. Therefore, the first pilot check valve 174A is open, and the pressure of the lower chamber 130A of the second hydraulic cylinder 130 is depressurized to the second system pressure.

[0263] Therefore, the working oil discharged from the other port of the second hydraulic pump / hydraulic motor P / M2 is supplied to the upper chamber 130B of the second hydraulic cylinder 130 via the hydraulic line 172. As the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130 descends, the working oil expelled from the lower chamber 130A of the second hydraulic cylinder 130 is drawn into one port of the second hydraulic pump / hydraulic motor P / M2. It should be noted that the cross-sectional area of ​​the upper chamber 130B of the second hydraulic cylinder 130 is larger than that of the lower chamber 130A. Therefore, when the buffer pad 110 descends, a portion of the working oil flowing into the second hydraulic pump / hydraulic motor P / M2 is supplied from the second accumulator 173.

[0264] In this way, the second hydraulic pump / hydraulic 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 can lower the buffer pad 110 by supplying working oil to the upper chamber 130B of the second hydraulic cylinder 130.

[0265] <Second Controller>

[0266] Next, the second controller 180 that controls the second hydraulic circuit 170 that drives the second hydraulic cylinder 130 will be described.

[0267] Figure 8 This is a block diagram illustrating a first embodiment of a second controller that controls the second hydraulic circuit.

[0268] like Figure 8As shown, a die buffer position signal indicating the position of the buffer pad 110 (die buffer position) is applied from the die buffer position detector 116 to the second controller 180 of the first embodiment; a slider position signal indicating the position of the slider 20 is applied from the slider position detector 26 to the second controller 180 of the first embodiment; 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 114 to the second controller 180 of the first embodiment.

[0269] In this example, the second controller 180 includes a die buffer position control unit 180A and a die buffer pressure control unit 180B.

[0270] The die buffer position control unit 180A mainly includes a die buffer position controller 181 and a die buffer position commander 182. A slider position signal is applied from the slider position detector 26 to the die buffer position commander 182, and the die buffer position commander 182 outputs a die buffer position command for controlling the position of the buffer pad 110 during periods other than the stamping process based on the input slider position signal.

[0271] In this example, the die buffer position instruction 182 outputs a first die buffer position instruction to put the buffer pad 110 in the die buffer standby position before stamping, a second die buffer position instruction to accelerate (pre-accelerate) the buffer pad 110 during the period from the die buffer standby position to the impact position after the first die buffer position instruction is output, a fourth die buffer position instruction to keep the buffer pad 110 in a position corresponding to the lower stop point of the slider 20, and a fifth die buffer position instruction to move the buffer pad 110 to the die buffer standby position after a certain period of time after the fourth die buffer position instruction is output.

[0272] When the second hydraulic cylinder 130 is in position control mode, the die buffer position controller 181 calculates a torque command for controlling the second servo motor SM2 based on the die buffer position command output from the die buffer position commander 182 and the die buffer position signal detected by the die buffer position detector 116, so that the position of the buffer pad 110 moves or remains according to the die buffer position command. When calculating the torque command, the angular velocity of the drive shaft of the second servo motor SM2 is preferably used as the angular velocity feedback signal to ensure dynamic stability.

[0273] When the second hydraulic cylinder 130 is in position control state, the die buffer position controller 181 of the second controller 180 outputs a torque command calculated using the die buffer position command and die buffer position signal to the second servo motor SM2 via the amplifier and PWM controller 185, thereby causing the piston rod 130C (buffer pad 110) of the second hydraulic cylinder 130 to move in the up and down direction or to keep the buffer pad 110 in the desired position.

[0274] It should be noted that when the die buffer position controller 181 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 the solenoid valve 175A via the amplifier 188, thereby enabling the supply of working oil to the lower chamber 130A of the second hydraulic cylinder 130 and the flow of working oil from the upper chamber 130B. Furthermore, when the die buffer position controller 181 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 the solenoid valve 175B via the amplifier 189, thereby enabling the supply of working oil to the upper chamber 130B of the second hydraulic cylinder 130 and the flow of working oil from the lower chamber 130A.

[0275] On the other hand, the die buffer pressure control unit 180B mainly includes a die buffer pressure controller 183 and a second pressure command unit 184. A slider position signal is applied from the slider position detector 26 to the second pressure command unit 184, and the second pressure command unit 184 outputs a die buffer pressure command (third pressure command) for pressure control of the second hydraulic cylinder 130 during stamping based on the input slider position signal.

[0276] In this example, the second pressure command unit 184 outputs a pressure command corresponding to the auxiliary die buffer force that assists the die buffer force (main die buffer force) generated by the first hydraulic cylinder 120 in the stamping process, or outputs a pressure command that makes the die buffer force generated by the second hydraulic cylinder 130 zero.

[0277] When the second hydraulic cylinder 130 is in pressure control mode, the die buffer pressure controller 183 calculates a torque command for driving the second servo motor SM2 based on the die buffer pressure command output from the second pressure command unit 184 and the pressure signal output from the second pressure detector 114, so as to control the pressure of the lower chamber 130A of the second hydraulic cylinder 130 according to the pressure command. When calculating the torque command, the angular velocity of the drive shaft of the second servo motor SM2 is preferably used as the angular velocity feedback signal to ensure dynamic stability.

[0278] Furthermore, when the second hydraulic cylinder 130 is in a pressure control state, the punching die buffer pressure controller 183 of the second controller 180 outputs the torque command calculated using pressure commands, pressure signals, etc., to the second servo motor SM2 via the amplifier and PWM controller 185. This controls the pressure of the lower chamber 130A of the second hydraulic cylinder 130 to a pressure corresponding to the auxiliary punching die buffer force, or controls the punching die buffer force generated by the second hydraulic cylinder 130 to zero.

[0279] It should be noted that when the die buffer pressure controller 183 outputs a torque command to supply working oil to the lower chamber 130A of the second hydraulic cylinder 130, it will output a drive signal to turn the solenoid valve 175A ON via the amplifier 188 to the solenoid valve 175A. This enables the pressurization of the lower chamber 130A of the second hydraulic cylinder 130 and enables the upper chamber 130B to be the second system pressure.

[0280] In addition, when the second hydraulic cylinder 130 is controlled to generate an auxiliary punching die buffer force, the second servo motor SM2 acts as a generator, and the power generated by the second servo motor SM2 is regenerated in the AC power supply 187 via the amplifier and PWM controller 185 and the DC power supply device 186 with power regeneration function.

[0281] On the other hand, when the pressure of the second hydraulic cylinder 130 is controlled so that the punching buffer force generated by the second hydraulic cylinder 130 is zero, the second hydraulic cylinder 130 will not hinder the punching buffer force generated by the first hydraulic cylinder 120.

[0282] The position control of the second hydraulic cylinder 130 by the die buffer position control unit 180A and the pressure control of the second hydraulic cylinder 130 by the die buffer pressure control unit 180B can be switched according to the position of the sliding member 20 and the crankshaft angle detected by the crankshaft encoder 28.

[0283] Alternatively, the second controller 180 can also perform only position control on the second hydraulic cylinder 130. In this case, the die buffer pressure control unit 180B is not required in the second controller 180.

[0284] Furthermore, preferably, during stamping, the die buffer position controller 182 of the die buffer position control unit 180A outputs a die buffer position command (third die buffer position command) corresponding to the position of the sliding member 20, and the die buffer position controller 181 controls the position of the second hydraulic cylinder 130 based on the third die buffer position command and the die buffer position signal. This allows for position control of the second hydraulic cylinder 130 to avoid obstructing the die buffer force generated by the first hydraulic cylinder 120.

[0285] It should be noted that in this example, when the pressure of the first hydraulic cylinder 120 and the second hydraulic cylinder 130 is controlled, 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 for the sake of simplicity. However, in order to control the punching and buffering force generated by the buffer pad 110 with good accuracy, the pressure of the upper chamber 120B of the first hydraulic cylinder 120 is preferably considered.

[0286] <First Control Method for the Die Buffer Device in the Second Embodiment>

[0287] Next, the first control method of the die buffer device of the second embodiment will be described.

[0288] Figure 9 It is a waveform diagram showing the position of the sliding member, the position of the die buffer, the pressure command (set pressure), and the actual pressure during a stamping cycle when the die buffer device is controlled by the first control method.

[0289] The first control method of the die buffer device 100-2 is particularly characterized by pre-pressurizing the pressure of the lower chamber 120A of the first hydraulic cylinder 120 to a preset pressure before stamping.

[0290] Before stamping, the downward pressure from the sliding member 20 of the stamping machine 10 is not applied to the buffer pad 110, so as long as it is not like... Figure 2 As shown, the buffer pad 110 abuts against the upper limit switch 15, and the rise of the buffer pad 110 is restricted, so the lower chamber 120A of the first hydraulic cylinder 120 cannot be pre-pressurized.

[0291] Therefore, while pre-pressurizing the buffer pad 110 before stamping, the die buffer device 100-2 simultaneously controls the die buffer pressure and the die buffer position. That is, the first hydraulic cylinder 120 is pressure-controlled for pre-pressurization, and the second hydraulic cylinder 130 is position-controlled to prevent the buffer pad 110 from moving from the die buffer standby position.

[0292] exist Figure 9 In the waveform diagram of a cycle shown, in the state earlier than the start of pre-pressurization t0, Figure 7 The first controller 160, which controls the first hydraulic circuit 140-3, preferably controls the pressure of the first hydraulic cylinder 120 while the second controller 180 is controlling the position of the second hydraulic cylinder 130, so that the first hydraulic cylinder 120 assists in supporting the weight of the buffer pad 110, etc. That is, the first controller 160 controls the first servo motor SM1 to apply pressure P0 from the first hydraulic pump HP to the lower chamber 120A of the first hydraulic cylinder 120 to support the weight of the buffer pad 110, etc.

[0293] It should be noted that, in the state earlier than the start of pre-pressurization t0, the first controller 160 turns the first solenoid valve 150 ON, so that the lower chamber 120A and upper chamber 120B of the first hydraulic cylinder 120 are connected to the system pressure line 144 to achieve equal pressure (first system pressure). When the buffer pad 110 is moved by the second hydraulic cylinder 130, the working oil of the first system pressure moves between the lower chamber 120A and upper chamber 120B of the first hydraulic cylinder 120.

[0294] on the other hand, Figure 8 The second controller 180 shown controls the position of the second hydraulic cylinder 130 by issuing a die buffer position command (first die buffer position command) to position the buffer pad 110 in the die buffer standby position X1. In this case, to keep the buffer pad 110 in the die buffer standby position X1 as indicated by the first die buffer position command, the second controller 180 rotates the second servo motor SM2 in one direction (first direction) or the other direction (second direction), adjusting the pressure applied from the second hydraulic pump / hydraulic motor P / M2 driven by the second servo motor SM2 to the lower chamber 130A and the upper chamber 130B of the second hydraulic cylinder 130. When the buffer pad 110 is held in the die buffer standby position X1, the cross-sectional area × pressure of the lower chamber 130A of the second hydraulic cylinder 130 is approximately the same as the cross-sectional area × pressure of the upper chamber 130B.

[0295] Then, when the slider 20 descends and the slider position reaches position X0 (higher than the height H of the punch buffer standby position X1), Figure 9 At time t0, the first controller 160 begins to pressurize the lower chamber 120A of the first hydraulic cylinder 120 to the pre-pressurization of the set pressure P1.

[0296] In this case, the first controller 160 drives the first hydraulic pump HP via the first servo motor SM1 based on a second pressure command to pre-pressurize to a preset pressure P1, and supplies pressurized oil from the first hydraulic pump HP to the lower chamber 120A of the first hydraulic cylinder 120, thereby performing pressure control so that the lower chamber 120A of the first hydraulic cylinder 120 becomes the set pressure P1.

[0297] The lower chamber 120A of the first hydraulic cylinder 120 is pressurized, thereby the first hydraulic cylinder 120 applies a force to the buffer pad 110 to make the buffer pad 110 rise.

[0298] When the buffer pad 110 is about to rise through pre-pressurization control, the second controller 180 controls the position of the second hydraulic cylinder 130 to keep the buffer pad 110 in the die buffer standby position X1 (to prevent the buffer pad 110 from rising).

[0299] Therefore, the buffer pad 110 remains in the die buffer standby position X1, and the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is pressurized (compressed) to the set pressure P1. In this state, the working oil does not flow from the first hydraulic pump HP to the lower chamber 120A of the first hydraulic cylinder 120, but in order to maintain the pressure in the lower chamber 120A of the first hydraulic cylinder 120 at the set pressure P1, the first controller 160 continuously drives the first servo motor SM1 to perform pressure control so that the pressure on the discharge side of the first hydraulic pump HP becomes the set pressure P1.

[0300] On the other hand, the second controller 180 performs position control on the second hydraulic cylinder 130 to keep the buffer pad 110 in the die buffer standby position. As a result, the second hydraulic cylinder 130 applies a force (a downward force) to the buffer pad 110 that cancels out the upward force applied to the buffer pad 110 by the first hydraulic cylinder 120.

[0301] Here, the upward force F1 applied from the first hydraulic cylinder 120 to the buffer pad 110 can be expressed by the following formula:

[0302] [Number 1]

[0303] F1 = Pressure of the lower chamber 120A of the first hydraulic cylinder 120 (set pressure P1) × cross-sectional area.

[0304] The downward force F2 applied from the second hydraulic cylinder 130 to the buffer pad 110 can be expressed by the following formula:

[0305] [Number 2]

[0306] F2 = Pressure of the upper chamber 130B of the second hydraulic cylinder 130 × Cross-sectional area.

[0307] Therefore, when the buffer pad 110 is held in the die buffer standby position and pre-pressurization is completed, F1 = F2.

[0308] It should be noted that in Equation [1], the first system pressure of the upper chamber 120B of the first hydraulic cylinder 120 is not considered, and in Equation [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 is approximately the same as the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130, the forces generated by the first system pressure and the second system pressure roughly cancel each other out, and the force F1 pushing the buffer pad 110 upward is approximately equal to the force F2 pressing the buffer pad 110 downward.

[0309] like Figure 9 As shown, the pre-pressurization can be completed before the sliding part reaches the die buffer standby position X1 (time t1).

[0310] The first controller 160 performs pressure control on the first hydraulic cylinder 120 so that even after the slider position reaches the die buffer standby position X1 (after impact), 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 stamping and the first pressure command that represents the die buffer pressure P1 corresponding to the die buffer force in stamping are the same pressure commands. 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 stamping period, i.e., from time t1 to time t2 (the time when the slider position reaches the lower stop).

[0311] On the other hand, when the slider position reaches the die buffer standby position X1 (time t1), the second controller 180 controls the position of the second hydraulic cylinder 130 based on the die buffer position command (third die buffer position command) corresponding to the slider position, thereby avoiding obstruction of the die buffer force generated by the first hydraulic cylinder 120.

[0312] Furthermore, when the sliding member reaches the die buffer standby position X1, the second controller 180 replaces the position control of the second hydraulic cylinder 130 and can switch to pressure control based on the third pressure command. The third pressure command is either a pressure command corresponding to the auxiliary die buffer force (main die buffer force) that assists the die buffer force (main die buffer force) generated by the first hydraulic cylinder 120 during stamping, or a pressure command that makes the die buffer force generated by the second hydraulic cylinder 130 zero.

[0313] Next, when the slider reaches the lower stop, the first controller 160 depressurizes the pressure in the lower chamber 120A of the first hydraulic cylinder 120 for a certain period of time from the time t2 when the lower stop 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 lower stop), performs pressure control to transfer to the first system pressure P0, and performs the pressure control required for product ejection after locking (after the start time t3).

[0314] On the other hand, when the slider reaches the lower stop, the second controller 180 performs position control (locking control) to keep the buffer pad 110 in the position corresponding to the lower stop based on the fourth die buffer position command during a certain period of time (locking period) from the time t2 to the time t3 when the lower stop is reached. Then, based on the fifth die buffer position command, the buffer pad 110 is raised and the position control is performed again to move to the die buffer standby position.

[0315] According to the first control method of the die buffer device, the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to the set pressure P1 before stamping, so that the force applied to the buffer pad 110 from the second hydraulic cylinder 130 can be zero immediately after the impact. Therefore, stamping can start from the moment of impact with the die buffer force required for forming (the set pressure P1 corresponding to the die buffer force).

[0316] In addition, by pre-pressurizing before stamping, the surge pressure during impact can be reduced compared to the case where no pre-pressurization is performed.

[0317] Furthermore, the second hydraulic cylinder 130 holds the buffer pad 110 in the die buffer standby position before stamping, so even if the impact position is wrong, the buffer pad 110 will not be pushed upward. Since the position control and pressure control are separated, there is an advantage that even if the position control that holds the buffer pad 110 in the die buffer standby position is switched to pressure control (or other position control) hastily (after impact), no malfunction will occur.

[0318] In addition, the standby position of the die buffer can be set freely, thereby increasing the variety of dies that can be handled by buffer pins of the same length.

[0319] <Second Control Method for Die Buffer Device>

[0320] Next, the second control method of the die buffer device will be explained.

[0321] Figure 10 It is a waveform diagram showing the position of the sliding member, the position of the die buffer, the pressure command (set pressure), and the actual pressure during a stamping cycle when the die buffer device is controlled by the second control method.

[0322] The second control method and use of the die buffer device Figure 9 Compared to the first control method of the die buffer device described above, the second control method adds a control to pre-accelerate the buffer pad 110 before stamping, which is different in this respect. It should be noted that in the second control method of the die buffer device, the detailed description of the parts shared with the first control method is omitted.

[0323] like Figure 10 As shown, the die buffer standby position X1' is a position above the height H2 of the impact position X2 at the start of stamping.

[0324] When the slider 20 descends, and the slider position reaches the position X0 of the height H1 of the punch buffer standby position X1' ( Figure 10At 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 the pre-pressurization of the set pressure P1. In addition, the second controller 180 performs position control on the second hydraulic cylinder 130 so that the buffer pad 110 is kept in the die buffer standby position X1'.

[0325] Next, the die buffer position command 182 of the second controller 180, before the slider position reaches the impact position ( Figure 10 At time t1), instead of outputting the first die buffer position command representing the die buffer standby position X1', a second die buffer position command is output to pre-accelerate the buffer pad 110.

[0326] The second controller 180 controls the position of the second hydraulic cylinder 130 based on the second die buffer position command, so that the buffer pad 110 is accelerated (pre-accelerated) before impact.

[0327] That is, the second controller 180 controls the second servo motor SM2 to supply working oil from the second hydraulic pump / hydraulic motor P / M2 to the upper chamber 130B of the second hydraulic cylinder 130, and the second hydraulic cylinder 130 causes the buffer pad 110 to descend (pre-accelerate in the downward direction).

[0328] 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.

[0329] Then, when the sliding part reaches the impact position X2 at the start of the stamping process... Figure 10 At time t2), the second controller 180 controls the position of the second hydraulic cylinder 130 based on the die buffer position command (third die buffer position command) corresponding to the current sliding member position. This avoids obstructing the die buffer force generated by the first hydraulic cylinder 120. It should be noted that the second controller 180 can also switch the control of the second hydraulic cylinder 130 from position control to pressure control during impact.

[0330] On the other hand, the first controller 160 continuously performs pressure control on the first hydraulic cylinder 120 in the same way as the pressure control during pre-acceleration.

[0331] Figure 10 Time t3 is the time when the slider reaches the lower stop point, and time t4 is the time when the locking ends. The first controller 160 and the second controller 180 are the same as the first control method, and switch to different pressure commands and position commands at times t3 and t4 to perform pressure control and position control.

[0332] It should be noted that in the position control performed by the second controller 180 that pre-accelerates the buffer pad 110, it is preferable to reduce the difference between the speed of the slider 20 and the speed of the buffer pad 110 during the impact.

[0333] According to the second control method of the die buffer device, the pressure of the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to the set pressure P1, and the buffer pad 110 is pre-accelerated. Therefore, the stamping and forming can begin from the moment of impact with the die buffer force required for forming. In addition, the excitation pressure during impact can be further reduced.

[0334] It should be noted that it can also be used as a substitute. Figure 7 The first hydraulic circuit 140-3 shown is applicable. Figure 2 The first hydraulic circuit 140-1 shown or Figure 4 The first hydraulic circuit 140-2 is shown. In this case, the position of the buffer pad 110 can be controlled by the second hydraulic cylinder 130, etc., so the upper limit switch 15 is not required. In addition, the first hydraulic circuit 140-1 cannot supply working oil to the lower chamber 120A of the first hydraulic cylinder 120, so the buffer pad 110 cannot be pre-pressurized when it is in the die buffer standby position. However, when the buffer pad 110 is pre-accelerated, pre-pressurization can be performed during the period from the start of pre-acceleration to the impact.

[0335] [Second Embodiment: Hydraulic Circuit for Die Buffer Device, etc., Applicable to the Second Embodiment]

[0336] Figure 11 This diagram illustrates a second embodiment, including the hydraulic circuit of the die buffer device applicable to the second embodiment, particularly showing the first hydraulic circuit 140-4 and the second hydraulic circuit 170. It should be noted that... Figure 11 In the middle, to and Figure 7 The parts common to the first embodiment of the hydraulic circuit, etc., shown are marked with the same reference numerals, and their detailed descriptions are omitted.

[0337] Figure 11 The second embodiment of the hydraulic circuit, etc., shown is similar to Figure 7 The difference lies in the use of a first hydraulic circuit 140-4 instead of a first hydraulic circuit 140-3, as shown in the first embodiment.

[0338] Figure 11 Compared to the first hydraulic circuit 140-3, the first hydraulic circuit 140-4 shown is equipped with a pilot-operated safety valve 157 instead of the first servo motor SM1 and hydraulic pump HP, which function as pressure generators.

[0339] A pilot-operated safety valve 157 is disposed between a throttling orifice 156, which functions as a throttling element, on the first hydraulic line 151 and the system pressure line 144, in order to apply pilot pressure to the pilot port P of the logic valve 148.

[0340] Along with the descent of the buffer pad 110 during stamping, the piston rod 120C of the first hydraulic cylinder 120 descends, the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is compressed, and the pressure in the lower chamber 120A rises.

[0341] Along with the pressure (die buffer pressure) passing through the lower chamber 120A of the first hydraulic cylinder 120, the oil flow (flow rate of pressurized oil per unit time) from the lower chamber 120A of the first hydraulic cylinder 120 through the die buffer pressure generating line 142, the throttle orifice 156 of the first hydraulic line 151, and the pilot-operated safety valve 157 to the system pressure line 144 generates a pilot pressure smaller than the die buffer pressure between the throttle orifice 156 and the pilot-operated safety valve 157. This pilot pressure is applied to the pilot port P of the logic valve 148 via the second solenoid valve 154, and the opening of the logic valve 148 in the die buffering process is adjusted.

[0342] It should be noted that the pilot-operated safety valve 157 adjusts the release pressure to generate the desired die buffer pressure in the lower chamber 120A of the first hydraulic cylinder 120.

[0343] This first hydraulic circuit 140-4 has no power source such as an oil pump, and its structure is the simplest compared to the first hydraulic circuits of other embodiments, making it an inexpensive device. Furthermore, the first controller for controlling the first hydraulic circuit 140-4 only needs to have the function of controlling the first solenoid valve 150 and the second solenoid valve 154.

[0344] On the other hand, the second hydraulic circuit 170 that drives the second hydraulic cylinder 130 is suitable for use with Figure 7 The circuit shown is the same circuit. Additionally, the second controller controlling the second hydraulic circuit 170 can also be applied to... Figure 8 The second controller 180 shown is the same controller.

[0345] Therefore, the position control of the buffer pad 110 can be achieved using the second hydraulic cylinder 130, the second hydraulic circuit 170, etc. By causing the second hydraulic cylinder 130 to descend according to the stamping speed, the buffer pad 110 can be pre-accelerated. In addition, the buffer pad 110 is automatically pre-pressurized by the first hydraulic cylinder 120 during pre-acceleration.

[0346] In addition, the control of the second hydraulic cylinder 130 can be switched from position control to pressure control, and the pressure control of the second hydraulic cylinder 130 can be performed in the die buffering process, thereby enabling the buffer pad 110 to generate die buffering force.

[0347] That is, in the die buffering process, the buffer pad 110 can generate a die buffering force (main die buffering force) based on the first hydraulic cylinder 120 and a die buffering force (auxiliary die buffering force) based on the second hydraulic cylinder 130. This increases the total die buffering force. Furthermore, since the auxiliary die buffering force is variable, the total die buffering force can also be variable. Moreover, in the die buffering process, the pressure fluctuations in the lower chamber 120A of the first hydraulic cylinder 120 caused by the hydraulic characteristics can be counteracted by controlling the pressure of the second hydraulic cylinder 130, thus making the total die buffering force a smooth force.

[0348] In addition, the main die buffer force in the total die buffer force can be provided by the first hydraulic cylinder 120, thus reducing the auxiliary die buffer force. The number of the second servo motor SM2 and the second hydraulic pump / hydraulic motor P / M2 in the second hydraulic circuit 170 that drives the second hydraulic cylinder 130 can be set to a minimum (1 unit in this example), so that the die buffer device as a whole can be set as an inexpensive device.

[0349] [A third embodiment applicable to the hydraulic circuit, etc., of the die buffer device of the second embodiment]

[0350] Figure 12 This is a diagram illustrating a third embodiment, such as the hydraulic circuit of the die buffer device applicable to the second embodiment, particularly showing the first hydraulic circuit 140-5 and the second hydraulic circuit 170. It should be noted that... Figure 12 In the middle, to and Figure 7 The parts common to the first embodiment of the hydraulic circuit, etc., shown are marked with the same reference numerals, and their detailed descriptions are omitted.

[0351] Figure 12 The second embodiment of the hydraulic circuit, etc., shown is similar to Figure 7 The difference lies in the use of a first hydraulic circuit 140-5 instead of a first hydraulic circuit 140-3, as shown in the first embodiment.

[0352] Figure 12 The first hydraulic circuit 140-5 shown is... Figure 2 Compared to the first hydraulic circuit 140-1 shown, instead of the first servo motor SM1 and hydraulic pump HP which function as pressure generators, a third hydraulic line (third hydraulic line) 152 is provided, which can connect the pilot port P of the logic valve 148 to the hydraulic line 171 of the second hydraulic circuit 170, and a third solenoid valve 158 for opening and closing the flow path of the third hydraulic line 152.

[0353] The third hydraulic line 152 and the third solenoid valve 158 function as pilot pressure application units, which make the pressure of the hydraulic line 171 of the second hydraulic circuit 170 (i.e., the pressure of the lower chamber 130A of the second hydraulic cylinder 130 connected to the hydraulic line 171) act as the pilot pressure of the control logic valve 148.

[0354] That is, when the third solenoid valve 158 is OFF ( Figure 12 In the state shown, the first hydraulic circuit 140-5 and the second hydraulic circuit 170 are disconnected as hydraulic circuits. However, when the third solenoid valve 158 is ON, the first hydraulic circuit 140-5 and the second hydraulic circuit 170 are connected via the third hydraulic line 152. The pressure of the hydraulic line 171 of the second hydraulic circuit 170 can be applied to the pilot port P of the logic valve 148 via the third hydraulic line 152 with the third solenoid valve 158 and the second solenoid valve 154.

[0355] Next, the function of the first hydraulic circuit 140-5 will be explained.

[0356] Before stamping, when the position of the buffer pad 110 is controlled by the second hydraulic cylinder 130, the first solenoid valve 150 is turned ON, connecting the lower chamber 120A and upper chamber 120B of the first hydraulic cylinder 120 to the system pressure line 144 respectively, thus setting an equal first system pressure. Therefore, when the buffer pad 110 is moved by the second hydraulic cylinder 130, the working oil of the first system pressure moves in the lower chamber 120A and upper chamber 120B of the first hydraulic cylinder 120.

[0357] In the die buffering process of stamping, the control of the second hydraulic cylinder 130 is switched from position control to pressure control. Additionally, the first solenoid valve 150 and the second solenoid valve 154 are turned off, and the third solenoid valve 158 is turned on. Thus, the pressure in the lower chamber 130A of the pressure-controlled second hydraulic cylinder 130 (the pressure of the hydraulic line 171) is applied as a pilot pressure to the pilot port P of the logic valve 148 via the third hydraulic line 152, the third solenoid valve 158, and the second solenoid valve 154.

[0358] The opening of the logic valve 148 is adjusted according to the pilot pressure, and the pressure in the lower chamber 120A of the first hydraulic cylinder 120 becomes a die buffer pressure that is slightly higher than the pilot pressure (pilot pressure + α).

[0359] The total die buffering force applied to the buffer pad 110 by the first hydraulic cylinder 120 and the second hydraulic cylinder 130 is the sum of the main die buffering force obtained by multiplying the cross-sectional area of ​​the lower chamber 120A of the first hydraulic cylinder 120 by (pilot pressure (= pressure of the lower chamber 130A of the second hydraulic cylinder 130) + α) and the auxiliary die buffering force obtained by multiplying the cross-sectional area of ​​the lower chamber 130A of the second hydraulic cylinder 130 by the pressure of the lower chamber 130A of the second hydraulic cylinder 130. Therefore, by controlling the pressure of the lower chamber 130A of the second hydraulic cylinder 130, the total die buffering force generated by the buffer pad 110 can be made to the set die buffering force.

[0360] In addition, the following method can be used to pre-pressurize the buffer pad 110 while it is in the die buffer standby position.

[0361] For example, when the control of the second hydraulic cylinder 130 is switched to pressure control and the pressure in the lower chamber 130A of the second hydraulic cylinder 130 becomes equivalent to the pilot pressure, the third solenoid valve 158 is turned off, sealing the pilot pressure applied from the hydraulic line 171 through the third hydraulic line 152, the third solenoid valve 158 and the second solenoid valve 154 to the pilot port P of the logic valve 148.

[0362] Next, while controlling the position of the second hydraulic cylinder 130, the buffer pad 110 is raised to a position slightly higher than the die buffer standby position, and then the position is controlled to descend to the die buffer standby position.

[0363] On the other hand, after the buffer pad 110 moves to a position slightly higher than the die buffer standby position, the first solenoid valve 150 is turned off to prevent the movement of the working oil of the first system pressure between the lower chamber 120A and the upper chamber 120B of the first hydraulic cylinder 120.

[0364] Subsequently, when the buffer pad 110 is moved (lowered) to the die buffer standby position by the second hydraulic cylinder 130, the working oil in the lower chamber 120A of the first hydraulic cylinder 120 is compressed along with the descent of the buffer pad 110. The working oil in the lower chamber 120A of the first hydraulic cylinder 120 is compressed to a pressure corresponding to the sealed pilot pressure applied to the pilot port P of the logic valve 148. Thus, the lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to a pressure corresponding to the sealed pilot pressure.

[0365] It should be noted that during the die-bearing buffer process, the third solenoid valve 158 is turned ON and the pressure in the lower chamber 130A of the second hydraulic cylinder 130 is set to the pilot pressure. However, as long as the pilot pressure sealed in the die-bearing buffer process does not decrease, the third solenoid valve 158 can remain OFF to continue sealing the pilot pressure.

[0366] The first hydraulic circuit 140-5, like the first hydraulic circuit 140-4, does not have a power source such as a hydraulic pump, and has a simple structure, making it an inexpensive device.

[0367] [other]

[0368] In this embodiment, there is one first hydraulic cylinder 120 that controls the pressure of the buffer pad 110, but the number of first hydraulic cylinders 120 is not limited to this. In addition, the number of second hydraulic cylinders 130 that are controlled independently of the first hydraulic cylinder 120 is not limited to this embodiment.

[0369] In addition, the second hydraulic circuit 170 that drives the second hydraulic cylinder 130 uses one servo motor + hydraulic pump / hydraulic motor for each second hydraulic cylinder 130, but is not limited to this, and the number of servo motor + hydraulic pump / hydraulic motor can be set to any number.

[0370] Furthermore, the second hydraulic circuit that drives the second hydraulic cylinder and the second controller that controls the second hydraulic circuit are not limited to this embodiment. They can at least be used to control the position of the second hydraulic cylinder, or they can be arbitrary.

[0371] In addition, it is explained that oil is used as the working fluid for the first hydraulic cylinder, the second hydraulic cylinder, the first hydraulic circuit, and the second hydraulic circuit, but it is not limited to this and water or other liquids may also be used.

[0372] Furthermore, the present invention is not limited to the above-described embodiments. It goes without saying that the present invention can be modified in various ways without departing from the spirit of the present invention.

Claims

1. A die buffer device, characterized in that, The die buffer device includes: The first hydraulic cylinder supports the buffer pad and causes the buffer pad to generate a die buffering force when the sliding part of the stamping machine descends; A first hydraulic circuit drives the first hydraulic cylinder; A first pressure command device, the output of which represents a first pressure command corresponding to the die buffer pressure of the die buffer force; A first pressure detector detects the pressure in the lower chamber of the first hydraulic cylinder; as well as A first controller controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector, so that the pressure applied to the lower chamber of the first hydraulic cylinder is the pressure corresponding to the first pressure command. The first hydraulic circuit is a closed hydraulic circuit. The hydraulic closed loop includes: The die buffer pressure generating line is connected to the lower chamber of the first hydraulic cylinder; The system pressure line is connected to a first accumulator that stores the working fluid at the first system pressure. A pilot-operated logic valve, with its A port connected to the die buffer pressure generation line and its B port connected to the system pressure line; and A pressure generator that generates pilot pressure acting on the pilot port of the logic valve. The first controller controls the pilot pressure based on the first pressure command and the pressure detected by the first pressure detector, controlling the pressure of the working fluid flowing from port A of the logic valve to port B, i.e., the pressure in the lower chamber of the first hydraulic cylinder, to the pressure corresponding to the first pressure command. The first hydraulic circuit has a first hydraulic line connecting the pressure generator to the die buffer pressure generation line, and a second hydraulic line connecting the upper chamber of the first hydraulic cylinder to the system pressure line. The first pressure command outputs a second pressure command to pre-pressurize the lower chamber of the first hydraulic cylinder to a preset pressure before stamping. Before stamping, the first controller controls the pressure generator 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, and the buffer pad abuts against the upper limit switch.

2. The die buffer device according to claim 1, wherein, The first hydraulic circuit has a first solenoid valve that opens and closes the flow path between the die buffer pressure generation line and the system pressure line. After stamping or after being locked for a certain period of time after stamping, the first controller opens the first solenoid valve so that the working fluid stored in the first accumulator at the first system pressure can be supplied to the lower chamber of the first hydraulic cylinder.

3. The die buffer device according to claim 1, wherein, A throttling device is provided between the first hydraulic line and the pilot port of the logic valve, or between the pressure generator and the pilot port of the logic valve.

4. The die buffer device according to any one of claims 1 to 3, wherein, 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.

5. The die buffer device according to any one of claims 1 to 3, wherein, The pressure generator comprises a hydraulic pump disposed between the system pressure line and the pilot port of the logic valve, and a first servo motor connected to the rotating shaft of the hydraulic pump. During stamping, the first controller controls the torque of the first servo motor based on the first pressure command and the pressure detected by the first pressure detector, thereby controlling the pilot pressure.

6. The die buffer device according to claim 1, wherein, The pressure generator is configured to include a first hydraulic pump / hydraulic motor disposed between the system pressure line and the first hydraulic line, and a first servo motor connected to the rotating shaft of the first hydraulic pump / hydraulic motor. The first pressure command device outputs the second pressure command before stamping. Before stamping, the first controller controls the first servo motor based on the second pressure command and the pressure detected by the first pressure detector, thereby causing the first hydraulic pump / hydraulic motor to function as a hydraulic pump and supply working fluid to the lower chamber of the first hydraulic cylinder, pre-pressurizing the pressure in the lower chamber of the first hydraulic cylinder to the pressure corresponding to the second pressure command. In the stamping process, the first controller controls the first servo motor based on the first pressure command and the pressure detected by the first pressure detector, so that the first hydraulic pump / hydraulic motor functions as a hydraulic motor, causing a portion of the working fluid pressed out from the lower chamber of the first hydraulic cylinder to flow to the system pressure line via the first hydraulic pump / hydraulic motor, and causing the remaining working fluid pressed out from the lower chamber of the first hydraulic cylinder to flow to the system pressure line via the logic valve, thereby controlling the pressure in the lower chamber of the first hydraulic cylinder to the pressure corresponding to the first pressure command.

7. A die buffer device, wherein, The die buffer device includes: The first hydraulic cylinder supports the buffer pad and causes the buffer pad to generate a die buffering force when the sliding part of the stamping machine descends; A first hydraulic circuit drives the first hydraulic cylinder; The second hydraulic cylinder supports the buffer pad and moves the buffer pad in the vertical direction; The second hydraulic circuit drives the second hydraulic cylinder; A first pressure command device, the output of which represents a first pressure command corresponding to the die buffer pressure of the die buffer force; A die buffer position instruction unit, which outputs a die buffer position instruction indicating the position of the buffer pad; A first pressure detector detects the pressure in the lower chamber of the first hydraulic cylinder; A die buffer position detector, which detects the position of the buffer pad; A first controller controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector, so that the pressure applied to the lower chamber of the first hydraulic cylinder becomes the pressure corresponding to the first pressure command. as well as The second controller controls the second hydraulic circuit based on the die buffer position command output from the die buffer position commander and the position of the buffer pad detected by the die buffer position detector, so that the position of the buffer pad is corresponding to the die buffer position command. The first hydraulic circuit is a closed hydraulic circuit. The hydraulic closed loop includes: The die buffer pressure generating line is connected to the lower chamber of the first hydraulic cylinder; The system pressure line is connected to a first accumulator that stores the working fluid at the first system pressure. A pilot-operated logic valve, with its A port connected to the die buffer pressure generation line and its B port connected to the system pressure line; and A pressure generator that generates pilot pressure acting on the pilot port of the logic valve. The first controller controls the pilot pressure based on the first pressure command and the pressure detected by the first pressure detector, controlling the pressure of the working fluid flowing from port A of the logic valve to port B, i.e. the pressure of the lower chamber of the first hydraulic cylinder, to the pressure corresponding to the first pressure command.

8. A die buffer device, wherein, The die buffer device includes: The first hydraulic cylinder supports the buffer pad and causes the buffer pad to generate a die buffering force when the sliding part of the stamping machine descends; A first hydraulic circuit drives the first hydraulic cylinder; The second hydraulic cylinder supports the buffer pad and moves the buffer pad in the vertical direction; The second hydraulic circuit drives the second hydraulic cylinder; A die buffer position instruction unit, which outputs a die buffer position instruction indicating the position of the buffer pad; A die buffer position detector, which detects the position of the buffer pad; as well as The second controller controls the second hydraulic circuit based on the die buffer position command output from the die buffer position commander and the position of the buffer pad detected by the die buffer position detector, so that the position of the buffer pad is corresponding to the die buffer position command. The first hydraulic circuit is a closed hydraulic circuit. The hydraulic closed loop includes: The die buffer pressure generating line is connected to the lower chamber of the first hydraulic cylinder; The system pressure line is connected to a first accumulator that stores the working fluid at the first system pressure. A pilot-operated logic valve, with its A port connected to the die buffer pressure generation line and its B port connected to the system pressure line; and A pilot pressure applying unit applies pilot pressure to the pilot port of the logic valve.

9. The die buffer device according to claim 8, wherein, The pilot pressure application unit is a pilot-operated safety valve disposed between the die buffer pressure generation line and the system pressure line.

10. The die buffer device according to claim 8, wherein, The pilot pressure application unit is a third hydraulic line that connects the pilot port of the logic valve to the lower chamber of the second hydraulic cylinder.

11. The die buffer device according to claim 10, wherein, The die buffer device is equipped with a third solenoid valve that opens and closes the flow path of the third hydraulic line.

12. The die buffer device according to any one of claims 7 to 11, wherein, The die buffer position command device outputs a first die buffer position command to put the buffer pad into the die buffer standby position before stamping. Before stamping, the second controller controls the second hydraulic circuit based on the first die buffer position command, so that the buffer pad is in standby position at the die buffer standby position.

13. The die buffer device according to claim 12, wherein, The die buffer standby position is located above the impact position at the start of the stamping process. After outputting the first die buffer position command, the die buffer position commander outputs a second die buffer position command that pre-accelerates the buffer pad during the period from the die buffer standby position to the impact position. The second controller controls the second hydraulic circuit based on the second die buffer position command, and pre-accelerates the buffer pad during the period from the die buffer standby position to the impact position.

14. The die buffer device according to any one of claims 7 to 11, wherein, The die buffer device includes: The second pressure command device outputs a third pressure command representing a preset third pressure; and The second pressure detector detects the pressure in the lower chamber of the second hydraulic cylinder. In the stamping process, the second controller controls the second hydraulic circuit based on the third pressure command and the pressure detected by the second pressure detector, and controls the pressure in the lower chamber of the second hydraulic cylinder to the third pressure corresponding to the third pressure command.

15. The die buffer device according to claim 14, wherein, The third pressure command is either the pressure command corresponding to the auxiliary die buffer force that assists the main die buffer force generated by the first hydraulic cylinder, or the pressure command that makes the die buffer force generated by the second hydraulic cylinder zero.

16. The die buffer device according to any one of claims 7 to 11, wherein, The die buffer position command device outputs a third die buffer position command corresponding to the position of the sliding member during the stamping process. The second controller controls the second hydraulic circuit based on the third die buffer position command during stamping, so that the buffer pad moves to the position of the buffer pad corresponding to the position of the slider.

17. The die buffer device according to any one of claims 7 to 11, wherein, When the slider reaches the lower stop point, the die buffer position command device outputs a fourth die buffer position command to hold the buffer pad in the position corresponding to the lower stop point. After outputting the fourth die buffer position command for a certain period of time, it outputs a fifth die buffer position command to move the buffer pad to the die buffer standby position. When the slider reaches the lower stop point, the second controller controls the second hydraulic circuit based on the fourth die buffer position command and the fifth die buffer position command, so that the buffer pad is held in the position corresponding to the lower stop point for a certain period of time, and then the buffer pad is moved to the die buffer standby position.

18. The die buffer device according to any one of claims 7 to 11, wherein, The second hydraulic circuit includes a second hydraulic pump / hydraulic motor connected between the upper and lower chambers of the second hydraulic cylinder, a second servo motor connected to the rotating shaft of the second hydraulic pump / hydraulic motor, a second accumulator for storing working fluid under the second system pressure, a first pilot check valve disposed in the flow path between the upper chamber of the second hydraulic cylinder and the second accumulator, and a second pilot check valve disposed in the flow path between the lower chamber of the second hydraulic cylinder and the second accumulator. When the second controller supplies working fluid from the second hydraulic pump / hydraulic motor to the upper chamber of the second hydraulic cylinder, it causes the second servo motor to rotate in a first direction, supplies working fluid from the second hydraulic pump / hydraulic motor to the upper chamber of the second hydraulic cylinder, and stores the working fluid extruded from the lower chamber of the second hydraulic cylinder in the second accumulator via the second pilot check valve. When the second controller supplies working fluid from the second hydraulic pump / hydraulic motor to the lower chamber of the second hydraulic cylinder, it causes the second servo motor to rotate in a second direction, supplies working fluid from the second hydraulic pump / hydraulic motor to the lower chamber of the second hydraulic cylinder, and stores the working fluid extruded from the upper chamber of the second hydraulic cylinder in the second accumulator via the first pilot check valve.

Images