Servo Die Cushion Control System for Press Accuracy
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Solution Overview
Problem
Conventional die cushion mechanisms using servomotors struggle to simultaneously control multiple die cushions effectively, leading to mechanical distortions and reduced accuracy in press machining due to the inability to suitably switch between force and position control modes across all cushions.
Innovation Solution
A control system with multiple control devices for each die cushion, capable of generating position and force commands, includes a switch judging part to determine when to switch control modes based on predetermined criteria, with a switching signal generating part coordinating the mode changes across all devices to prevent simultaneous position and force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple die cushions are independently controlled by individual control devices, then each die cushion can be controlled separately, but mechanical distortion occurs in the cushion pad due to simultaneous position and force control
Solution Approach 1:
The patent merges the control modes of multiple die cushions by introducing a central control device that coordinates the switching between position control and force control across all die cushions. This ensures that all die cushions operate in the same control mode simultaneously, preventing mechanical distortion while maintaining independent controllability.
Solution Approach 2:
The control device monitors the operational state of each die cushion and uses feedback signals to determine when to switch between control modes. Based on detected parameters such as cushion pad position and force, the system automatically switches from position control to force control or vice versa, ensuring coordinated operation across all die cushions.
2Reliability
If force control is applied to all die cushions simultaneously, then pressure can be maintained, but the system cannot adapt to varying drawing requirements
Solution Approach 1:
The control system dynamically switches between position control and force control modes based on the operational phase and requirements. During initial stages, position control ensures precise positioning; during drawing operations, force control maintains appropriate pressure. This dynamic adaptation allows the system to meet both reliability and adaptability requirements.
Solution Approach 2:
The system changes the control parameter from position to force (or vice versa) based on detected conditions such as cushion pad displacement and applied force. This parameter switching enables the system to maintain pressure when needed while adapting to varying drawing requirements through mode transitions.
3Measurement precision
If position control is used for all die cushions, then positioning accuracy is maintained, but force application becomes excessive leading to mechanical distortion
Solution Approach 1:
The system dynamically transitions from position control to force control when the cushion pad reaches a predetermined position or when excessive force is detected. This prevents continuous excessive force application while maintaining positioning accuracy during the approach phase, thereby eliminating mechanical distortion.
Solution Approach 2:
The control device detects when position control is causing excessive force and preemptively switches to force control mode before mechanical distortion occurs. This preliminary action prevents the harmful effect of excessive force while maintaining the benefits of accurate positioning during the approach phase.
Data Source
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AI summary
A control system (10), for a press machine including a plurality of die cushions (4), by which force control and position control may be suitably switched from one to another in each control device for each of the die cushions. The control system includes a plurality of control devices for controlling a servomotor (5) of each die cushion and a switching signal generating part capable of collecting the judgment result of each control device. The switching signal generating part transmits a switching signal to each control device, in order to switch the control mode of each control device.