Rolling Stand Roll Shift Control for Wear Dispersion and Crown Stability
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Solution Overview
Problem
The existing wear dispersion method for rolling stands, which involves changing the opposite direction shift to disperse wear, often fails to maintain the equivalent roll crown, leading to defects in plate crown and flatness, especially under thermal expansion and fluctuating rolling loads, and requires limited bender load compensation.
Innovation Solution
A method that combines opposite and same direction shifts of work rolls with cubic or higher-order polynomial roll diameter distributions, using a roll gap adjusting device to maintain the equivalent roll crown by adjusting screw down positions, thereby dispersing wear while maintaining the required roll gap differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opposite direction shift is changed to disperse wear, then wear dispersion is improved, but equivalent roll crown cannot be maintained leading to plate crown and flatness defects
Solution Approach 1:
The invention segments the shift control into two independent components: opposite direction shift amount (δc) for wear dispersion and same direction shift amount (δp) for maintaining equivalent roll crown. This allows independent optimization of wear dispersion and plate quality without mutual interference, resolving the contradiction between wear dispersion and manufacturing precision.
Solution Approach 2:
The invention adds a new control dimension by introducing same direction shift (δp) in addition to the traditional opposite direction shift (δc). This dimensional expansion allows the system to simultaneously achieve wear dispersion (through δc) and maintain equivalent roll crown (through δp), solving the contradiction that previously required sacrificing one objective for the other.
2Manufacturing precision
If bender load is increased to compensate for equivalent roll crown, then plate crown is improved, but bender load variability is restricted reducing productivity
Solution Approach 1:
The invention separates the functions of wear dispersion (handled by opposite direction shift δc) and equivalent roll crown maintenance (handled by same direction shift δp). This segmentation eliminates the need to use bender load for compensating equivalent roll crown changes, thereby restoring full bender load variability for productivity improvements while maintaining plate crown through a different mechanism.
Solution Approach 2:
The invention introduces same direction shift (δp) as an intermediary mechanism to maintain equivalent roll crown, replacing the previous direct reliance on bender load adjustment. This intermediary approach allows bender load to focus solely on plate crown compensation and thermal expansion compensation, improving productivity while maintaining manufacturing precision.
3Manufacturing precision
If work roll is replaced frequently to prevent uneven wear, then plate quality is improved, but operation efficiency deteriorates
Solution Approach 1:
The invention implements periodic same direction shift (δp) to maintain equivalent roll crown while dispersing wear. This periodic control approach allows the work roll to be used for extended periods without replacement, as the system actively manages wear distribution and crown maintenance, thereby improving operation efficiency while maintaining plate quality.
Solution Approach 2:
The invention enables the rolling mill system to self-correct for wear and crown changes through automated shift control (δc and δp), eliminating the need for frequent manual work roll replacements. The system monitors and adjusts shifts to maintain plate quality, allowing work rolls to serve their full functional life and improving productivity.
Data Source
AI summary
When an opposite direction shift for obtaining a required equivalent roll crown and a same direction shift for wear dispersion are used in combination, a difference occurs in the roll gap at both edge portions in the width direction of a rolling target material. Therefore, the difference between a work-side screw down position and a drive-side screw down position is changed so that the roll gap difference between both the edge portions in the width direction of the rolling target material is made close to zero. As a result, the distance between the work roll shafts on a work side and a drive side is changed, so that the roll gap difference at both ends in the width direction of the rolling target material approaches zero. Therefore, the wear of the work rolls can be dispersed while maintaining the equivalent roll crown.