Plate Straightening PID Control for Yield Strength Variation
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Solution Overview
Problem
Existing plate straightening methods fail to account for uneven temperature distribution and resulting changes in yield strength across different parts of a high-temperature plate, leading to inaccuracies in straightening force calculations and poor straightening results.
Innovation Solution
A dynamic PID method that adjusts straightening roll reductions based on real-time changes in yield strength using a PID controller, incorporating numerical approximation and closed-loop control to minimize errors in straightening force predictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a unified yield strength is used to calculate straightening force for the whole plate, then the calculation process is simple, but the straightening precision deteriorates due to temperature distribution unevenness
Solution Approach 1:
The plate is divided into multiple sections (head, middle, tail) with different yield strengths based on temperature distribution. Each section is processed independently with its own straightening force calculation, allowing precise control while maintaining manageable complexity through modular segmentation.
Solution Approach 2:
Different yield strength values are assigned to different sections of the plate according to their local temperature conditions. The head, middle, and tail sections each use their own yield strength parameters, enabling localized optimization of straightening force for each region rather than applying a uniform approach.
2Ease of manufacture
If the straightening process is calculated at initial temperature, then the process is straightforward, but the straightening force accuracy deteriorates due to temperature changes during straightening
Solution Approach 1:
The straightening process transitions from static initial temperature calculation to dynamic temperature tracking. The system continuously monitors temperature changes during straightening and adjusts yield strength parameters in real-time, making the calculation adaptive to changing conditions while maintaining processability through systematic updates.
Solution Approach 2:
Temperature measurements during straightening are fed back into the calculation system to update yield strength values. The measured temperature data from each section is used to recalculate the appropriate straightening force, creating a closed-loop control system that improves accuracy while maintaining straightforward processing through iterative refinement.
3Ease of operation
If a unified straightening reduction is applied to all rolls, then the control process is simple, but the straightening uniformity deteriorates due to yield strength variations
Solution Approach 1:
The straightening reduction is segmented by roll position and plate section. Each straightening roll applies a customized reduction based on the local yield strength requirements of the plate section it processes, enabling uniform straightening across the entire plate while maintaining simple control through systematic assignment of reduction values to specific rolls.
Solution Approach 2:
Different straightening reduction values are applied to different straightening rolls according to their position and the local yield strength requirements. The control system assigns specific reduction parameters to each roll based on the plate's temperature distribution, achieving localized optimization while maintaining overall process simplicity.
Data Source
AI summary
The invention provides a dynamic proportional-integral-derivative (PID) method for plate straightening based on changes in yield strength. The method includes the steps of determining yield strength of a plate at an initial temperature; calculating a predicted straightening force of each straightening roll based on the yield strength; obtaining a measured straightening force of each straightening roll; determining yield strength errors Δσfront, Δσmiddle, and Δσrear using a numerical approximation method; determining parameters of a PID controller based on the yield strength errors Δσfront, Δσmiddle, and Δσrear; calculating a target reduction of a corresponding straightening roll based on the yield strength error Δσmiddle and the yield strength at the initial temperature; and adjusting a measured reduction of the current straightening roll using the PID controller with the parameters determined based on the target reduction.