Servo Press Slide Position Control via Phase-Switched Loop
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Solution Overview
Problem
Existing servo press control methods, such as semi-closed loop and full-closed loop control, face challenges in responding to mechanical alterations like thermal expansion and high-speed driving with low mechanical rigidity, often requiring additional components like linear encoders, which increase costs and restrict attachment options.
Innovation Solution
A servo press system that switches between semi-closed loop and full-closed loop control near the stop position, utilizing an increment-type linear encoder to detect the Z-phase signal, allowing for stable control without additional components like linear encoders, even in systems with low mechanical rigidity and oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semi-closed loop control is used, then the control system is simple and responsive, but it cannot respond to mechanical alterations such as thermal expansion
Solution Approach 1:
The control system dynamically switches between semi-closed loop control and full-closed loop control based on the operational phase. During approach and contact phases, semi-closed loop control is used for simplicity and responsiveness. During positioning phases where thermal expansion affects accuracy, full-closed loop control is activated to compensate for mechanical alterations, thus adapting the system characteristics to match operational requirements.
2Manufacturing precision
If full-closed loop control is used, then positioning accuracy is improved, but oscillation occurs when mechanical rigidity is low
Solution Approach 1:
The system dynamically adjusts the control mode based on mechanical rigidity conditions. When mechanical rigidity is low, the system uses semi-closed loop control to avoid oscillation. When rigidity is sufficient and positioning accuracy is critical, full-closed loop control is employed. This dynamic adaptation prevents instability while maintaining precision where feasible.
Solution Approach 2:
The control process is segmented into different phases (approach, contact, positioning). Full-closed loop control is applied only during specific positioning phases where high accuracy is needed and mechanical conditions are favorable, while semi-closed loop control handles other phases. This segmentation allows precision improvement without incurring oscillation problems throughout the entire operation.
3Manufacturing precision
If a scale is provided over the entire driving range to enable high-speed driving with full-closed loop control, then positioning accuracy is maintained, but the scale becomes long and attachment is restricted
Solution Approach 1:
The full-closed loop control with scale is applied only to specific positioning phases rather than the entire driving range. The scale is installed only where needed for high-precision positioning, not throughout the complete travel distance. This segmented application reduces the required scale length and simplifies attachment while maintaining positioning accuracy during critical operations.
Solution Approach 2:
Instead of providing full-closed loop control with scale over the entire driving range, the system applies it partially only where necessary for high-precision positioning. This partial action approach achieves the required manufacturing precision without the excessive complexity and attachment restrictions of a complete-scale solution.
Data Source
AI summary
There is provided a servo press capable of performing press working with high accuracy without an increased cost, for example, without any additional special component such as a linear encoder or the like even in a system in which deviation occurs due to disturbances, as well as a control method and a program disturbance. A sensing element is disposed at a stop position of a slide. A servomotor control unit performs: semi-closed loop control based on information detected by a first slide position detection unit disposed at a servomotor, before a signal detection unit detects a signal from the sensing element, and full-closed loop control based on information detected by a second slide position detection unit, after the signal detection unit detects the signal from the sensing element.