Die Cushion Force Control Method for Press Vibration Suppression
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Solution Overview
Problem
Existing die cushion force control methods experience significant vibration issues, particularly initial large overshoots and undershoots, due to excessive response during the impact between a slide and a cushion pad, leading to problems like blank breakage and wrinkles, which conventional solutions fail to effectively address.
Innovation Solution
A die cushion force control method that outputs an initial die cushion force command value equal to or larger than the target, then decreases continuously to suppress overshoot, and subsequently increases to match the target value, taking into account the response delay between command output and force generation, thereby reducing vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stepwise target die cushion force command value is used, then the control is simple, but initial large overshoot occurs causing blank breakage
Solution Approach 1:
The control method performs preliminary action by outputting a die cushion force command value equal to or larger than the target value before the actual impact occurs. This anticipatory command suppresses the initial large overshoot that would otherwise cause blank breakage, while maintaining control simplicity without complex apparatus modifications.
Solution Approach 2:
The control method applies dynamics by continuously or stepwise decreasing the die cushion force command value after the initial command, and then subsequently increasing it to match the target value. This dynamic adjustment of the command value throughout the impact process eliminates both initial and subsequent overshoots, achieving manufacturing precision while keeping the control system relatively simple.
2Ease of manufacture
If conventional die cushion force control is used, then equipment cost is low, but vibration occurs causing wrinkles
Solution Approach 1:
The control method implements feedback by continuously monitoring the die cushion force and adjusting the command value accordingly. The system detects when the force reaches a local maximum point and switches from a first force command value to a second force command value that decreases to the set value, suppressing recurring undershoots and vibrations that cause wrinkles while maintaining cost-effectiveness.
Solution Approach 2:
The control method applies parameter changes by dynamically modifying the die cushion force command value based on the detected force state. By switching between different command values (first force command value and second force command value) depending on whether the force is increasing or decreasing, the system achieves stable die cushion force without requiring expensive hardware modifications.
3Manufacturing precision
If force command value is switched at local maximum point, then subsequent undershoot is suppressed, but initial large overshoot cannot be prevented
Solution Approach 1:
The control method performs preliminary action by outputting an initially large die cushion force command value equal to or larger than the target value before the impact completes. This anticipatory command prevents the initial large overshoot from occurring in the first place, rather than reacting after it happens, thereby achieving manufacturing precision without excessive response time.
Solution Approach 2:
The control method applies dynamics by continuously adjusting the die cushion force command value throughout the impact process - initially outputting a large value, then decreasing it continuously or stepwise, and subsequently increasing it to match the target. This dynamic approach eliminates both initial and subsequent overshoots while maintaining appropriate response timing.
Data Source
AI summary
A die cushion force control method and a die cushion apparatus generates a die cushion force on a cushion pad based on a die cushion force command value set in advance. A die cushion force command value equal to or larger than a target die cushion force command value is outputted initially in order to suppress an initial die cushion force overshoot generated when the target die cushion force command value configured to be stepwise is used as the die cushion force command value, then a die cushion force command value decreased continuously (gradually) so as to be smaller than the target die cushion force command value is outputted, and subsequently a die cushion force command value increasing gradually so as to be equal to the target die cushion force command value is outputted.