Die-Cushion Controller Bottom Dead Center Positioning
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Solution Overview
Problem
Existing die-cushion controlling devices struggle to accurately stop the die-cushion pad at the bottom dead center position due to fluctuations caused by plate-thickness errors and processing inaccuracies in workpieces, leading to unreliable bottom dead center locking.
Innovation Solution
A die-cushion controlling device with a position-command-signal outputting section, position detecting means, position comparing section, speed controlling section, and an output switching section that adjusts the position command signal based on position deviation, ensuring accurate positioning and switching between position and pressure control to stabilize the die-cushion pad at the bottom dead center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed target bottom dead center position is determined for the die-cushion pad, then the position control can be simplified, but the actual bottom dead center positions fluctuate due to plate-thickness error and processing error of the workpiece, causing the target position to not coincide with the actual bottom dead center position
Solution Approach 1:
The patent applies feedback by detecting the actual bottom dead center position of the die-cushion pad and using this detected position as the target position value for position control. The position detecting means continuously monitors the die-cushion pad position, and the detected actual bottom dead center position is fed back to update the target position, ensuring the target always coincides with the actual bottom dead center despite workpiece variations.
Solution Approach 2:
The patent implements preliminary action by detecting the actual bottom dead center position in advance and setting it as the target position before the next pressing operation begins. This ensures that the position control system is already configured with the correct target position when the die-cushion pad approaches the bottom dead center, allowing for accurate positioning in the subsequent cycle.
2Ease of operation
If the die-cushion pad is controlled to stop at a predetermined target position, then the control system is simple to operate, but it cannot accurately stop at the actual bottom dead center position when the slide reaches bottom dead center
Solution Approach 1:
The system uses feedback from the position detecting means to automatically determine the actual bottom dead center position and update the target position accordingly. This eliminates the need for manual adjustment or complex operator intervention, maintaining ease of operation while achieving accurate bottom dead center locking through automatic adaptation to actual positions.
3Productivity
If the control switches from position control to pressure control based on servo motor current change, then drawing can be favorably conducted, but the switching timing may not precisely coincide with the actual bottom dead center position
Solution Approach 1:
The patent uses feedback from the position detecting means to monitor the die-cushion pad position in real-time. The control switching timing is determined based on the detected position signal showing that the die-cushion pad has reached its bottom dead center position, ensuring precise switching timing that coincides with the actual bottom dead center rather than relying on indirect current change detection.
Data Source
AI summary
A die-cushion controlling device includes: a position-command-signal outputting section for outputting a position command signal of a die-cushion pad; a position detecting means for detecting a position of the die-cushion pad; a position comparing section for outputting a position deviation signal corresponding to a deviation between the target position value based on the position command signal and a position detection value based on a position detection signal; a position controlling section for outputting a position-speed command signal based on the position deviation signal; a speed controlling section for outputting a motor-current command signal based on the position-speed command signal from the position controlling section; a servo amplifier for generating a current corresponding to the motor-current command signal; and an output switching section that, based on a press signal output when a slide has reached a bottom dead center, switches the position detection signal from the position detection means to the position command signal from the position command signal outputting section.