Die cushion control device

a control device and cushion technology, applied in the field ofdie cushion control devices, can solve the problems of time lag between the provision of a control signal and a response, difficult control, and large impact for

Inactive Publication Date: 2006-08-03
FANUC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014] When the die cushion members are under position control, the servomotor for driving the die cushion members is provided with torque limits, and the servomotor does not output torque of a predetermined value or more. Therefore, even if the upper die hits the die cushion members due to malfunctions or wrong operation, the die cushion members do not generate drag equal to or more than a torque limit value. This prevents damage to the die fixed to the press axis, the die cushion members, etc.

Problems solved by technology

In the case of die cushion control using hydraulic or pneumatic pressure, however, there is time lag between provision of a control signal and a response.
For this reason, it is difficult to carry out the control in such a way that the sheet metal does not receive surge pressure that is created by impact at the beginning of the press.
On this account, during die change or during position control as in adjustment of the press machine and the like, if the upper die driven by the press axis driving device hits the die cushion member, or if the press axis is driven with a foreign matter pinched between the die cushion member and the upper die fixed to the press axis to apply great force to the die cushion member and the like, great impact force is created, which does a lot of damage to the die cushion member and the die in some cases.
The servomotor then generates great torque in order to maintain the commanded position, which causes the problem that there occurs a mechanical damage such as damage to the die cushion member.

Method used

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Examples

Experimental program
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first embodiment

[0020]FIG. 1 is a schematic view of a press machine in which a die cushion control device of the present invention is applied. A lower die 2 of a set of dies is fixed to a base of the press machine, and an upper die 1 is driven by a press axis driving device (not shown), so as to face the lower die 2. The press axis driving device may be constituted by a crank mechanism, by a hydraulic or pneumatic pressure mechanism, or by a position control mechanism using a servomotor, thereby driving the upper die 1 according to a predetermined pattern and moving the same upward and downward in the figure.

[0021] A plurality of die cushion members 6 are disposed on the lower die 2 side. The die cushion members 6 are configured so that they are driven by respective servomotors Md in the vertical direction in the figure. In the example shown in FIG. 1, the die cushion members 6 and the die cushion servomotors Md are provided in two pairs. However, there may be provided a plurality of pairs, that is...

second embodiment

[0046] In the second embodiment, the position control is continued after the upper die 1 is brought into contact to the die cushion members 6 through the sheet metal 3, and is afterward switched to the pressure control. Consequently, if the velocity of the press axis is high for some reason, such as erroneous setting and wrong operation, and the upper die 1 hits against the die cushion members 6 at an unscripted high velocity, there is the possibility of generation of great impact force. However, even in the period of the position control before the changeover switch 16 is switched to the “b”-side, since the output torque of the servomotors is limited by the torque limiter 15, torque equal to or more than that is not produced, and the die cushion members 6 move downward with the upper die 1. Accordingly, there generates no great impact force in the die cushion members 6, the upper die 1 and the like, so that the upper die 1 and the die cushion members 6 are protected.

[0047] In each ...

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Abstract

Die cushion control device that implements die cushion control while making a switch between position control and pressure control by using servomotors, and reduces the impact caused by a collision between a press axis and a die cushion axis during position control. Die cushion members are controlled by servomotors Md. The changeover switch is connected to the “a”-side, to thereby control the position (velocity) of the servomotors Md by commands from a numerical controller and control the position of the die cushion members. During position control, the output torque of the servomotors Md is limited by torque limit means. During position control, even if the press axis hits the die cushion members due to erroneous setting, wrong operation or the like, the servomotors Md merely output only a limited torque or less, so that impact force is reduced, which prevents damage to the die cushion members and the press axis. During press operation, when a position detector detects that the press axis moves downward to reach a predetermined position, the changeover switch is connected to the “b”-side, to thereby implement pressure control.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a die cushion control device for performing a die cushion control in a press machine. [0003] 2. Description of Related Art [0004] In a press machine, when sheet metal is pressed between a set of dies by relative motion of the set of dies along a press axis, a die cushion control is performed in order to prevent the sheet metal from being applied with abrupt pressure and to moderate a change of pressure applied to the sheet metal. [0005] A die cushion control device of the press machine conventionally performs hydraulic or pneumatic pressure control. An upper die movably provided by a press axis driving device moves downward to hit the sheet metal, and subsequently, the die cushion control device implements pressure control. In the case of die cushion control using hydraulic or pneumatic pressure, however, there is time lag between provision of a control signal and a response. For thi...

Claims

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Application Information

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IPC IPC(8): B21D24/08
CPCB21D24/02
InventorHISHIKAWA, TETSUOFUJIBAYASHI, KENTAROTSUJIKAWA, KEISUKEHIROSE, NOBORU
OwnerFANUC LTD