Servo Die Cushion Control Device for Rapid Slide Acceleration
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Solution Overview
Problem
Conventional die cushion mechanisms using servomotors struggle to accurately control force during rapid acceleration or deceleration of the slide in press machines, leading to force deviations and low-frequency vibrations, which hinder productivity and accuracy.
Innovation Solution
A control device for the die cushion mechanism that includes a force commanding part, a force detecting part, a speed commanding part, a speed detecting part, a current commanding part, and a correcting part to adjust commanded values based on detected forces and speeds, specifically correcting for slide acceleration to maintain commanded force and prevent vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the force gain is increased for rapid acceleration or deceleration of the slide, then the force control response is improved, but vibration at low frequency occurs in the machine during gradual acceleration or deceleration
Solution Approach 1:
The control device dynamically adjusts the force gain based on the actual acceleration or deceleration state of the slide. When rapid acceleration or deceleration is detected, the force gain is increased to improve response. When gradual acceleration or deceleration occurs, the force gain is reduced to prevent vibration. This dynamic adjustment resolves the contradiction between speed response and stability.
Solution Approach 2:
The force gain parameter is changed according to the acceleration or deceleration conditions of the slide. The control device monitors the slide's motion state and modifies the force gain parameter in real-time, increasing it during rapid changes and decreasing it during gradual changes, thereby achieving both fast response and stability.
2Device complexity
If the force gain is kept constant for constant pressure control, then the control system is simple, but the force cannot follow the commanded force during rapid acceleration or deceleration of the slide
Solution Approach 1:
The force gain transitions from a constant value to a dynamically adjustable parameter based on slide acceleration or deceleration detection. This dynamic approach maintains simplicity by only adjusting the gain when motion changes are detected, while significantly improving force control accuracy during rapid acceleration or deceleration events.
Solution Approach 2:
The force gain parameter is modified based on the detected acceleration or deceleration state of the slide. When rapid motion changes are detected, the force gain is increased to ensure the actual force follows the commanded force accurately, thereby improving manufacturing precision without substantially increasing system complexity.
3Productivity
If the slide is rapidly accelerated or decelerated to increase productivity, then the press working speed is improved, but the force deviates from the commanded force due to constant force gain
Solution Approach 1:
The force gain parameter is adjusted according to the slide's acceleration or deceleration rate. During rapid acceleration or deceleration, the force gain is increased to maintain force control accuracy and ensure the actual force follows the commanded force, thereby enabling high-speed operation without sacrificing precision.
Solution Approach 2:
The control system dynamically adapts the force gain to match the slide's motion state, enabling rapid acceleration or deceleration for improved productivity while maintaining force control accuracy through real-time parameter adjustment.
Data Source
AI summary
A control device of a die cushion mechanism, by which a force between a slide and a die cushion may follow a commanded value even in the rapid acceleration or deceleration of the slide and, moreover, a problem such as vibration of the mechanism may be prevented in the gradual acceleration or deceleration of the slide. The control device includes a slide position detecting part, such as a position sensor, for detecting the position of the slide and a correcting part for correcting a current commanded value using an acceleration of the slide, obtained by second-order differentiation of the position of the slide detected by the position sensor.