Servo Press Thermal Expansion Compensation
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Solution Overview
Problem
Semi-closed loop control in servo presses is unable to respond effectively to mechanical alterations due to thermal expansion, affecting the accuracy of press working processes.
Innovation Solution
A servo press system that includes a slide, servomotor, encoder, sensing elements, and a correction value calculation unit, which measures thermal expansion using a sensing element separate from the servo system to correct operational distances and improve accuracy by calculating and applying correction values based on reference and processing sensing values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semi-closed loop control is used to control the servo press by monitoring the encoder of the servomotor, then the control system is simple and cost-effective, but the system cannot respond to mechanical alteration such as thermal expansion, resulting in degraded press working accuracy
Solution Approach 1:
The control system is segmented into two independent parts: the existing semi-closed loop servomotor control system and a new independent linear encoder measurement system. The linear encoder separately measures the actual position of the slide to detect thermal expansion, while the servomotor controller continues its normal operation. This segmentation allows the system to maintain simplicity while adding thermal expansion compensation capability.
Solution Approach 2:
A linear encoder is introduced as an intermediary measurement device between the slide and the control system. This intermediary independently measures the actual position of the slide, providing thermal expansion data without interfering with the existing servomotor control. The measured position is then used to calculate correction values that compensate for thermal effects.
2Manufacturing precision
If a linear encoder is added to measure thermal expansion, then press working accuracy is improved, but the device complexity increases
Solution Approach 1:
Instead of implementing a complete full-closed loop control system which would require complex integration, the patent applies partial action by only measuring the position at the stop point using a linear encoder. This selective measurement approach provides sufficient thermal expansion data for correction without requiring continuous position feedback or complex control algorithm modifications.
Solution Approach 2:
The system creates a simplified copy of the position measurement function using a linear encoder specifically for thermal expansion detection. Rather than replacing the existing encoder system or implementing a complex full-closed loop, a separate but simpler measurement copy is added that focuses solely on detecting positional drift due to thermal effects.
3Measurement precision
If continuous position reading is performed to monitor thermal expansion, then measurement accuracy is improved, but processing load and costs increase
Solution Approach 1:
The system performs periodic position measurement only at the stop point rather than continuous monitoring. The linear encoder measures the slide position at each stopping cycle, providing sufficient data to detect thermal expansion trends over time. This periodic measurement approach reduces processing load while maintaining adequate measurement precision for thermal compensation.
Solution Approach 2:
The system performs preliminary measurement of the stop position using the linear encoder before thermal expansion significantly affects subsequent operations. By measuring at each stop point, the system captures position data before the next heating cycle begins, allowing correction values to be calculated and applied in advance for the following operation cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables highly accurate press working while responding to mechanical alterations due to thermal expansion, reducing processing load and costs by using a linear encoder independently and minimizing continuous position reading.
Implementation Method 1
a sensing element configured to sense a stop position of the slide
Implementation Method 2
a servomotor configured to drive the slide up and down
Implementation Method 3
an encoder disposed at the servomotor; a slide position detecting unit configured to detect a position of the slide based on an output signal from the encoder
Data Source
AI summary
Highly accurate press working is performed while responding to mechanical alteration due to thermal expansion. Prior to a series of processing to a workpiece, a servomotor control unit moves a slide to a stop position, and a sensing value detecting unit detects a sensing value of a sensing element at the stop position of the slide, and stores the detected sensing value. Then, in the series of processing, the sensing value detecting unit detects a sensing value of the sensing element at the stop position of the slide, and stores the detected sensing value in the processing sensing value storing unit. A correction value calculating unit calculates a correction value based on the two store values, and a servomotor control unit controls the servomotor based on the detected slide position, the slide position that has been set, and the correction value calculated by the correction value calculating unit.