Rolling Stand Gap Control for Stable Roll Force Distribution
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Solution Overview
Problem
In continuous rolling systems, maintaining stable roll force distribution across multiple stands is challenging due to temperature changes, roll diameter variations from thermal expansion and abrasion, and the resulting gap errors, which can lead to irregular strip thickness and roll force imbalances, potentially causing shape defects and output saturation.
Innovation Solution
A continuous rolling system with a roll force distribution control device that includes a setting calculation unit, actual data collection unit, mass flow thickness correction unit, target strip thickness correction unit, tracking unit, and gap operation unit, which calculates and applies gap correction values and target strip thickness correction values to synchronize roll force ratios across stands, preventing gap errors and maintaining constant roll force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous rolling is performed without stopping, then productivity is improved, but roll force distribution becomes unstable due to temperature changes and roll diameter variations
Solution Approach 1:
The control device continuously monitors actual roll forces at each stand and compares them with target values, then automatically adjusts roll gaps in real-time to maintain stable roll force distribution throughout the continuous rolling process
Solution Approach 2:
The system calculates and sets target roll forces and roll gap adjustments in advance based on material properties and rolling conditions, preparing correction values before they are needed during the rolling process
2Manufacturing precision
If roll gap is adjusted to compensate for temperature changes, then strip thickness control is improved, but roll force increases further
Solution Approach 1:
The control device uses feedback from actual roll force measurements to determine the appropriate roll gap adjustment amount, automatically calculating the correction needed to maintain target roll force while achieving desired strip thickness
3Device complexity
If roll force distribution is not controlled, then device complexity is reduced, but shape defects and unbalanced abrasion occur
Solution Approach 1:
The control device automatically performs all calculations and adjustments without manual intervention, using sensor data from the rolling line to self-regulate roll gaps and maintain optimal roll force distribution across all stands
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
This solution ensures stable rolling by maintaining constant roll force distribution, preventing roll force concentration on specific stands, reducing the risk of shape defects, and avoiding unbalanced abrasion, thereby ensuring consistent product quality.
Implementation Method 1
The strip thickness gauge 2c is placed on a delivery side of a final stand (the N-th stand) and measures the strip thickness of the material to be rolled 2b
Implementation Method 2
Each of load cells 3d is placed on a strut that supports a chock part of the lower-side backup roll 3b. The load cells 3d detect roll force (rolling force)
Implementation Method 3
Encoders 3e are mounted at chock ends of the work rolls 3a and detect the roll rotational speed of the work rolls 3a
Implementation Method 4
Each of hydraulic cylinders 3c is mounted at a chock part of the backup rolls 3b. The hydraulic cylinders 3c adjust a roll gap by moving upward and downward
Data Source
AI summary
When the tracking point reaches the i-th stand, the continuous rolling system outputs, to an i-th stand, a roll gap operation value for bringing to zero a difference between a value which is obtained by correcting a strip thickness target value of the i-th stand with a target strip thickness correction value of the i-th stand and a value which is obtained by correcting a strip thickness actual recalculation value of the i-th stand with a gap correction value of the i-th stand. Here, the gap correction value is a correction value that brings to zero a difference between a head end gap error when a head end of the material to be rolled reaches the i-th stand and a non-head end gap error when a part other than the head end of the material to be rolled reaches the i-th stand.