Variable-Thickness Hot Rolling Mill Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hot continuous rolling mills face difficulties in achieving precise variable-thickness control of strip steel due to challenges in roller gap control and second flow balance, limiting the application of variable-thickness hot rolling technology.
Innovation Solution
A method involving two control strategies - equal-thickness and variable-thickness control - where the load distribution and roller gap adjustments are managed across stands to achieve targeted thickness variations along the longitudinal direction, ensuring precision and stability by determining participating stands based on section length, thickness variation, and rolling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable-thickness control is implemented on conventional hot continuous rolling mill, then the capability to produce strip steel with different thicknesses is improved, but the rolling stability deteriorates due to second flow imbalance
Solution Approach 1:
The strip steel production process is segmented into multiple equal-thickness sections along the longitudinal direction. Each section can have independent target thickness values, allowing the mill to produce variable-thickness strip by controlling each segment separately while maintaining rolling stability within each segment.
Solution Approach 2:
Different sections of the strip steel are assigned different thickness specifications according to local requirements. The roller gap and rolling parameters are adjusted locally for each section rather than uniformly across the entire strip, enabling precise control of thickness distribution while maintaining overall process stability.
2Manufacturing precision
If roller gap is adjusted for variable-thickness control, then the thickness precision is improved, but the control complexity increases due to timing sequence and velocity matching requirements
Solution Approach 1:
The target thickness values for each equal-thickness section are predetermined and the roller gap adjustments are planned in advance. The control system pre-calculates the required roller gap positions and timing sequences for each section before rolling begins, simplifying the real-time control process while achieving precise thickness control.
Solution Approach 2:
The roller gap is made dynamically adjustable during the rolling process. Each stand's roller gap can be independently controlled in real-time according to the specific thickness requirements of different sections, enabling precise variable-thickness control while the system adapts to the changing rolling conditions.
3Manufacturing precision
If multiple stands participate in variable-thickness control, then the thickness distribution control is improved, but the difficulty of velocity matching and loop stability increases
Solution Approach 1:
The rolling process is divided into discrete equal-thickness sections, and stands are selectively engaged for control in each section. This segmentation allows the system to manage velocity matching and thickness control in smaller, more manageable units rather than coordinating all stands simultaneously across the entire strip length.
Solution Approach 2:
The control system dynamically adjusts rolling parameters including stand velocities and roller gap positions for each equal-thickness section. By changing these parameters section by section rather than uniformly, the system achieves better thickness distribution control while managing the complexity of multi-stand coordination.
Data Source
AI summary
The present invention relates to a method for producing hot rolled strip steel, especially the producing method of hot rolled strip steel with multiple target thicknesses in the longitudinal direction. It is a method to produce the strip steel with different target thicknesses in the longitudinal direction by using a hot continuous rolling mill. In this method, the first equal-thickness section of the strip steel is controlled with the conventional thickness control strategy, while other equal-thickness sections and the transition section between equal-thickness sections are controlled with the variable-thickness control strategy. Under the variable-thickness control strategy, the length of the first section of strip steel, the variation of thickness target value, the rolling stability and the spacing between stands are combined to determine the stand participating in the variable-thickness control, and calculate the roller gap value, as well as the time and speed of the variation of roller gap, thus achieving the producing control of strip steel with different target thicknesses in the longitudinal direction. The present invention utilizes the length of the first equal-thickness section and the variation of different target thicknesses and other related factors to determine the stands participating in the control, and then distributes the load variation among the stands, thus effectively avoiding the influence on the rolling stability due to imbalance of second flow, so that the produced strip with variable thickness in different sections in the longitudinal direction meet the user's requirements.