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CN-114643327-B - Die buffering device

CN114643327BCN 114643327 BCN114643327 BCN 114643327BCN-114643327-B

Abstract

The invention provides a die cushion device, which can well pre-pressurize a cushion pad when the cushion pad is positioned at a die cushion standby position. The die cushion device of the invention is provided with a1 st hydraulic cylinder (120) and a2 nd hydraulic cylinder (130) which are respectively and independently controlled at the same time. When the cushion pad (110) is pre-pressurized, the 1 st hydraulic cylinder (120) is pressure-controlled via the 1 st hydraulic circuit (140) so that the pressure of the lower chamber (120A) of the 1 st hydraulic cylinder (120) is pre-pressurized to a preset pressure, and the 2 nd hydraulic cylinder (130) is position-controlled via the 2 nd hydraulic circuit (150) so that the cushion pad (110) is held at the die cushion standby position. The 1 st hydraulic cylinder (120) balances the force that lifts the cushion pad (110) with the force that lowers the cushion pad (110) by the 2 nd hydraulic cylinder (130) (the force that remains in the die cushion standby position).

Inventors

  • Nearly rattan is loyal rich

Assignees

  • 会田工程技术有限公司

Dates

Publication Date
20260508
Application Date
20211214
Priority Date
20201218

Claims (13)

  1. 1. A die cushion device is characterized by comprising: A1 st hydraulic cylinder that supports a cushion pad and generates a die cushion force when a slide table of a press machine descends; a1 st hydraulic circuit that drives the 1 st hydraulic cylinder; a1 st pressure command unit that outputs a1 st pressure command indicating a die cushion pressure corresponding to the die cushion force; a1 st pressure detector that detects a pressure applied to a lower chamber of the 1 st hydraulic cylinder; a 1 st controller that controls the 1 st hydraulic circuit based on the 1 st pressure command and the pressure detected by the 1 st pressure detector so that the pressure applied to the lower chamber of the 1 st hydraulic cylinder becomes a pressure corresponding to the 1 st pressure command; a2 nd hydraulic cylinder that supports the cushion pad and moves the cushion pad in an up-down direction; A2 nd hydraulic circuit that drives the 2 nd hydraulic cylinder; a die cushion position command unit that outputs a die cushion position command indicating a position of the cushion pad; a die cushion position detector for detecting the position of the cushion pad, and A2 nd controller that controls the 2 nd hydraulic circuit based on the die cushion position instruction and the position of the cushion pad detected by the die cushion position detector so that the position of the cushion pad becomes a position corresponding to the die cushion position instruction, The 1 st pressure commander outputs a2 nd pressure command for pre-pressurizing the pressure of the lower chamber of the 1 st hydraulic cylinder to a preset pressure before press molding, The die cushion position commander outputs a1 st die cushion position commander that causes the cushion pad to stand by in a die cushion standby position before press molding, The 1 st controller controls the 1 st hydraulic circuit based on the 2 nd pressure command and the pressure detected by the 1 st pressure detector to pre-pressurize the pressure of the lower chamber of the 1 st hydraulic cylinder to a pressure corresponding to the 2 nd pressure command, When the lower chamber of the 1 st hydraulic cylinder is pre-pressurized based on the 2 nd pressure command, the 2 nd controller controls the 2 nd hydraulic circuit based on the 1 st die cushion position command to standby the cushion pad at the die cushion standby position, The 1 st pressure commander outputs the 2 nd pressure commander during a period from a time before press molding to a time when press molding is started.
  2. 2. The die cushion device of claim 1, wherein, The 1 st hydraulic circuit is constituted by a die cushion pressure generating line connected to a lower chamber of the 1 st hydraulic cylinder, a system pressure line connected to an upper chamber of the 1 st hydraulic cylinder and a 1 st accumulator for accumulating a 1 st system pressure working fluid, respectively, a 1 st hydraulic pump/motor connected between the die cushion pressure generating line and the system pressure line, and a 1 st servo motor connected to a rotation shaft of the 1 st hydraulic pump/motor, The 1 st controller controls the torque of the 1 st servo motor based on the 1 st pressure command or the 2 nd pressure command and the pressure detected by the 1 st pressure detector.
  3. 3. The die cushion device of claim 1, wherein, The 1 st hydraulic circuit is a hydraulic closed circuit including a die cushion pressure generation line connected to a lower chamber of the 1 st hydraulic cylinder, a system pressure line to which a1 st accumulator for accumulating the 1 st system pressure working fluid is connected, a pilot-driven logic valve having an A port connected to the die cushion pressure generation line and a B port connected to the system pressure line, a1 st electromagnetic valve for opening and closing a flow path between the die cushion pressure generation line and the system pressure line, a pressure generator for generating a pilot pressure acting on a pilot port of the logic valve, and a1 st hydraulic line for connecting the pressure generator and the die cushion pressure generation line, The 1 st controller controls the pilot pressure based on the 1 st pressure command or the 2 nd pressure command and the pressure detected by the 1 st pressure detector, and controls the pressure on the a port side of the logic valve, that is, the pressure of the lower chamber of the 1 st hydraulic cylinder, to a pressure corresponding to the 1 st pressure command or the 2 nd pressure command.
  4. 4. The die cushion device of claim 3, wherein, A restrictor is provided in the 1 st hydraulic line.
  5. 5. The die cushion device according to claim 3 or 4, wherein, The 1 st hydraulic circuit has a 2 nd hydraulic line connecting an upper chamber of the 1 st hydraulic cylinder and the system pressure line.
  6. 6. The die cushion device according to claim 3 or 4, wherein, The 1 st hydraulic circuit has a 2 nd solenoid valve that selectively applies the 1 st system pressure or the pilot pressure to a pilot port of the logic valve.
  7. 7. The die cushion device according to claim 3 or 4, wherein, The pressure generator is composed of a hydraulic pump arranged between the system pressure line and the pilot port of the logic valve, and a3 rd servo motor connected to the rotation shaft of the hydraulic pump, The 1 st controller controls the pilot pressure by controlling the torque of the 3 rd servo motor based on the 1 st pressure command or the 2 nd pressure command and the pressure detected by the 1 st pressure detector.
  8. 8. The mold buffer according to any one of claim 1 to 4, wherein, The die buffering standby position is a position above the collision position at which the press molding starts, The die cushion position commander outputs a 2 nd die cushion position command for pre-accelerating the cushion pad before the position of the slide table reaches the collision position after outputting the 1 st die cushion position command, The 2 nd controller controls the 2 nd hydraulic circuit based on the 2 nd die cushion position command, and pre-accelerates the cushion pad during a period from the die cushion standby position to the collision position.
  9. 9. The mold buffer according to any one of claim 1 to 4, wherein, The die cushion device comprises: a2 nd pressure command unit for outputting a3 rd pressure command indicating a3 rd pressure set in advance, and A 2 nd pressure detector that detects a pressure of a lower chamber of the 2 nd hydraulic cylinder, The 2 nd controller controls the 2 nd hydraulic circuit based on the 3 rd pressure command and the pressure detected by the 2 nd pressure detector in press forming, and controls the pressure of the lower chamber of the 2 nd hydraulic cylinder to the 3 rd pressure corresponding to the 3 rd pressure command.
  10. 10. The die cushion device of claim 9, wherein, The 3 rd pressure command is a pressure command corresponding to an auxiliary die cushion force that assists the main die cushion force generated by the 1 st hydraulic cylinder, or a pressure command that makes the die cushion force generated by the 2 nd hydraulic cylinder zero.
  11. 11. The mold buffer according to any one of claim 1 to 4, wherein, The die buffering position command device outputs a 3 rd die buffering position command corresponding to the position of the sliding table in the compression molding, The 2 nd controller controls the 2 nd hydraulic circuit based on the 3 rd die cushion position instruction in press forming so that the cushion pad moves to a die cushion position corresponding to the position of the slide table.
  12. 12. The mold buffer according to any one of claim 1 to 4, wherein, When the slide table reaches a bottom dead center, the die cushion position commander outputs a 5 th die cushion position command for moving the cushion pad to the die cushion standby position after outputting a4 th die cushion position command for holding the cushion pad at a position corresponding to the bottom dead center for a certain time, And if the slide table reaches the bottom dead center, the 2 nd controller controls the 2 nd hydraulic circuit based on the 4 th die cushion position command and the 5 th die cushion position command, and moves the cushion pad to the die cushion standby position after holding the cushion pad at a position corresponding to the bottom dead center for a certain time.
  13. 13. The mold buffer according to any one of claim 1 to 4, wherein, The 2 nd hydraulic circuit includes a2 nd hydraulic pump/motor connected between an upper chamber and a lower chamber of the 2 nd hydraulic cylinder, a2 nd servo motor connected to a rotation shaft of the 2 nd hydraulic pump/motor, a2 nd accumulator for accumulating a2 nd system pressure working fluid, a1 st pilot check valve provided in a flow path between the lower chamber of the 2 nd hydraulic cylinder and the 2 nd accumulator, and a2 nd pilot check valve provided in a flow path between the upper chamber of the 2 nd hydraulic cylinder and the 2 nd accumulator, The 2 nd controller performs: When the hydraulic fluid is supplied from the 2 nd hydraulic pump/motor to the upper chamber of the 2 nd hydraulic cylinder, the 2 nd servo motor is rotated in the 1 st direction, the hydraulic fluid is supplied from the 2 nd hydraulic pump/motor to the upper chamber of the 2 nd hydraulic cylinder, the hydraulic fluid discharged from the lower chamber of the 2 nd hydraulic cylinder is accumulated in the 2 nd accumulator via the 1 st pilot check valve, and when the hydraulic fluid is supplied from the 2 nd hydraulic pump/motor to the lower chamber of the 2 nd hydraulic cylinder, the 2 nd servo motor is rotated in the 2 nd direction, the hydraulic fluid is supplied from the 2 nd hydraulic pump/motor to the lower chamber of the 2 nd hydraulic cylinder, and the hydraulic fluid discharged from the upper chamber of the 2 nd hydraulic cylinder is accumulated in the 2 nd accumulator via the 2 nd check valve.

Description

Die buffering device Technical Field The present invention relates to a die cushion device, and more particularly to a technique for pressurizing (pre-pressurizing) a cushion pad when the cushion pad is located at a die cushion standby position. Background Conventionally, a die cushion device has been proposed which can pre-pressurize a cushion pad when the cushion pad is located at a die cushion standby position (patent document 1). The die cushion device described in patent document 1 includes a hydraulic cylinder that supports a cushion pad and generates a die cushion force when a slide table of a press machine is lowered, a1 st hydraulic circuit connected to a head side hydraulic chamber (lower chamber) of the hydraulic cylinder, and a 2 nd hydraulic circuit connected to a rod side hydraulic chamber (upper chamber), wherein when the cushion pad is located at a die cushion standby position, outflow of working oil from the upper chamber of the hydraulic cylinder is blocked by a pilot-driven check valve of the 2 nd hydraulic circuit, and pressurized oil is supplied to the lower chamber of the hydraulic cylinder by the 1 st hydraulic circuit, thereby pre-pressurizing the cushion pad. Prior art literature Patent literature Patent document 1 JP-A2017-113786 In the die cushion device described in patent document 1, when the cushion pad is located at the die cushion standby position, the hydraulic oil in the upper chamber of the hydraulic cylinder is compressed and the cushion pad slightly rises because the hydraulic oil is supplied to the lower chamber of the hydraulic cylinder while the outflow of the hydraulic oil in the upper chamber of the hydraulic cylinder is prevented, and the cushion pad is pre-pressurized. For example, in a die cushion device having a maximum die cushion force of 2000kN, the cushion pad rises by 9mm according to the sectional area ratio of the cylinder upper chamber to the lower chamber by pre-pressurizing of 400kN (20% of the maximum die cushion force), and the condition for increasing the rising amount of the cushion pad is not an allowable level. Specifically, the following conditions (1) and (2) are no longer "tolerable levels". (1) With the rise of the cushion pad, the upper surface (position) of the blank holder (punch) is relatively higher than the upper surface (position) of the lower die (punch), and deflection occurs in the mounted material, which affects the processing accuracy. (2) When the blank (material) is supplied from outside the press at the raised position due to the rising of the bead ring of (1), it is also necessary to correct the track of the conveyor. The die cushion device described in patent document 1 also has a problem of a deviation (instability) of the standby position of the die cushion per cycle of pressing. Further, as another problem caused by the "rise due to compression", as shown in fig. 3 of patent document 1, there is a problem that the hydraulic oil in the rod side hydraulic chamber 120b of the hydraulic cylinder 120 is compressed, and the cushion pad 110 rises by the rising amount x, so if the cushion pad 110 does not fall by the amount x, the pressure in the cylinder upper chamber does not drop to the level of the holding pressure PR0 (the pressure corresponding to the system pressure of the present application described later). In this way, if the holding pressure PR0 is not reduced, the upward force that is originally the damping force is offset by the downward force amount, and as a result, the target die damping force cannot be reached immediately after the collision. In order to solve the problem of the rising of the die cushion waiting position due to the pre-pressurization, a control method is considered in which the upper chamber of the hydraulic cylinder is closed in the middle of the rising of the cushion pad by the position control to raise the pressure, and the control is performed so that the final raised pressure value becomes a pre-pressurized pressure command, whereby the cushion pad does not rise from the die cushion waiting position. In this case, there is a problem that the pre-pressurization per cycle of the pressing is deviated. The deviation of the pre-pressurization at the die cushion standby position (the difference in load at the time of collision) has a large correlation with the stability of the product quality. Disclosure of Invention The present invention has been made in view of such circumstances, and an object thereof is to provide a die cushion device capable of satisfactorily pre-pressurizing a cushion pad when the cushion pad is located at a die cushion standby position. In order to achieve the above object, a die cushion device according to claim 1 of the present invention is characterized by comprising a1 st hydraulic cylinder that supports a cushion pad so that the cushion pad generates a die cushion force when a slide table of a press machine is lowered, a1 st hydraulic circuit that drives the 1 st hydra