Press Machine Bottom Dead Center Position Correction Control
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Solution Overview
Problem
High-speed press machines face challenges in maintaining constant die height due to thermal deformation, frictional heat, and changing press speeds, leading to unstable position correction control and hunting phenomena, which existing bottom dead center position correction control sections cannot effectively manage.
Innovation Solution
A press machine with a bottom dead center position correction control section that determines the press speed state and selects between single-cycle and multi-cycle control modes, using average value calculations and torque limit control to stabilize position correction, ensuring accurate and efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If position correction control is performed corresponding to each press cycle when press speed is in a stable state, then die height can be maintained constant, but hunting phenomenon occurs and control becomes unstable as press speed increases
Solution Approach 1:
The control system dynamically adapts its operation mode based on press speed state. When press speed is in a changing state (acceleration or deceleration), the system performs position correction control for each press cycle. When press speed is in a stable state, the system switches to multi-cycle control to prevent hunting phenomenon. This dynamic adaptation resolves the contradiction between maintaining die height consistency and ensuring control stability at different operating conditions.
Solution Approach 2:
The control parameters are changed based on press speed state. The system monitors whether the press speed is in a changing state or stable state, and accordingly adjusts the control frequency and method. This parameter change allows the system to maintain effective position correction during speed transitions while avoiding unstable hunting oscillations during stable high-speed operation.
2Reliability
If position correction control is not performed during acceleration or deceleration periods, then control stability is maintained, but die height changes occur and product accuracy decreases
Solution Approach 1:
The control system is designed to be dynamic rather than static, automatically detecting whether the press is in acceleration/deceleration phases or stable operation. During acceleration or deceleration, the system activates position correction control for each press cycle to maintain die height. During stable operation, it switches to multi-cycle control for stability. This dynamic behavior ensures both control stability and product accuracy are maintained under different operating conditions.
3Reliability
If a wide correction unnecessary range (dead zone) is used to reduce hunting phenomenon, then control stability improves, but position correction responsiveness decreases
Solution Approach 1:
The dead zone parameter is made dynamic rather than fixed. The system adjusts the correction unnecessary range based on press speed state: during changing states (acceleration/deceleration), a smaller dead zone is used to maintain responsiveness; during stable states, a larger dead zone is applied to prevent hunting phenomenon. This dynamic adjustment resolves the contradiction between control stability and position correction responsiveness.
Data Source
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AI summary
A press machine includes a bottom dead center position correction control section (51,53), a speed state determination section that determines the actual press speed, a control cycle count setting section (57), and a mode selection control section that selects a single-cycle control mode when the actual press speed is in a changing state, and selects a set multi-cycle control mode when the actual press speed is in a stable state. The bottom dead center position correction control section (51,53) performs position correction control corresponding to each press cycle in the single-cycle control mode, and performs position correction control corresponding to each control multi-cycle count set by the control cycle count setting section in the set multi-cycle control mode.