Reversible Cold Rolling Mill Coil Building-Up Method
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Solution Overview
Problem
The existing cold rolling equipment for small- to medium-scale steel production faces challenges such as high off-gage rates, increased initial costs due to complex configurations, and reduced production efficiency, particularly in plants with annual production capacities of 300,000 to 600,000 tons, where the cost-effectiveness of equipment is a concern.
Innovation Solution
A reversible cold rolling method and equipment design that includes a coil building-up step, reversible rolling, and controlled cutting, with a focus on maintaining a coil outside diameter of less than ϕ3000, gradual tension adjustment, and the use of a mash seam welding system to reduce off-gage rates and enhance production efficiency while minimizing initial costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a coil building-up line is used to join multiple coils to form a long buildup coil, then the strip length is enlarged and off-gage rate is reduced, but the device complexity and initial cost increase
Solution Approach 1:
The coil building-up process segments the handling of multiple individual coils by joining them into one continuous buildup coil, reducing the frequency of operations at coil leading end and tail end sections. This segmentation approach concentrates unrolled portions to only the innermost and outermost circumferential portions of the buildup coil, significantly reducing off-gage rate while maintaining manageable equipment complexity
Solution Approach 2:
Multiple coils are preliminarily joined together to form a buildup coil before the actual cold rolling process begins. This preliminary action of coil joining eliminates the need for repeated coil handling during rolling passes, reducing off-gage generation and improving production efficiency without requiring excessively complex equipment
2Manufacturing precision
If reversible rolling is performed multiple times to reduce strip thickness, then the desired product thickness is achieved, but the number of deceleration and acceleration operations increases, reducing production efficiency
Solution Approach 1:
The buildup coil enables continuous rolling operations with fewer interruptions. By having a long continuous strip from the buildup coil, the rolling mill can maintain steady-state operation for extended periods, reducing the frequency of deceleration and acceleration cycles while still achieving the required thickness reduction through multiple passes
Solution Approach 2:
The system dynamically adjusts rolling parameters during each pass while maintaining overall process efficiency. The buildup coil's extended length allows for optimized rolling schedules where the mill can operate at high speed for most of the rolling process, with speed adjustments only when necessary for pass transitions or when approaching the end of the buildup coil
3Length of moving object
If the buildup coil outside diameter is enlarged to increase coil length, then more coils can be joined, but the rolling tension increases coil tightening force causing shrinkage toward the inside diameter
Solution Approach 1:
The system optimizes the buildup coil outside diameter parameter to balance coil length requirements with acceptable tightening forces. By controlling the coil diameter within reasonable limits and adjusting winding tension parameters, the system achieves sufficient coil length for reduced off-gage operations while preventing excessive tightening forces that would cause unwanted shrinkage or deformation
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 approach significantly reduces off-gage rates, improves production efficiency, and curtails initial investment costs by allowing the use of collapsible reels, preventing stop marks, and ensuring accurate strip thickness and shape control, thus maintaining high yield and cost-effectiveness in small- to medium-scale steel production.
Implementation Method 1
a joining device for joining the strips together by welding to form a buildup coil
Data Source
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AI summary
Disclosed are cold-rolled material manufacturing equipment and a cold rolling method by which a high investment cost-effectiveness is realized while maintaining a high efficiency and a high yield in a small- to medium-scale plant with a capacity of about 300,000 to 600,000 tons of product per year. Input coils 101a to 101c unwound from a unwinding device 2 are joined together by a joining device 5, a buildup coil 102 having an outside diameter of not more than Φ3000 is formed at a winding/unwinding device 6, and the buildup coil 102 is subjected to reversible cold rolling a predetermined number of times by a cold rolling mill 1 between winding/unwinding devices 3 and 4 until a desired product strip thickness is reached. In the final pass, while being rolled at a slow speed for example, 2 mpm by the cold rolling mill 1, the buildup coil 102 is cut up by a cutting device 7a or 7b, thereby forming a plurality of output coils 103a to 103c, which are extracted from the winding/unwinding device 3 and carried out.