Reversible Cold Rolling Mill Coil Buildup System
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Solution Overview
Problem
Current cold-rolled material manufacturing equipment, particularly in small- to medium-scale plants with annual production of 300,000 to 600,000 tons, faces challenges such as high off-gage rates, increased initial costs due to complex configurations, high welding machine costs, thickness variations at joint portions, elongated coil issues, and inefficiencies in coil cutting processes, which affect production efficiency and cost-effectiveness.
Innovation Solution
A reversible cold rolling method and equipment that involves a plurality of passes with changing rolling directions, using a collapsible type reel, a mash seam welding system, and controlled rolling speeds to minimize off-gage rates, simplify equipment configuration, and maintain high-quality surface gloss, while reducing initial costs by eliminating the need for additional winding/unwinding devices and using a mash seam welding system for cost-effective joint formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reversible rolling system is used to manufacture cold-rolled materials, then equipment can be used for both winding and unwinding of strip, but off-gage rate increases to about 2.5% due to unrolled sections at leading end and tail end portions
Solution Approach 1:
The coil buildup line joins multiple coils to form a single long coil before rolling, so that the leading end and tail end unrolled sections are generated only at the innermost and outermost circumferential portions of the buildup coil, not at each pass switching point
2Adaptability or versatility
If reversible rolling is performed multiple times to achieve desired strip thickness, then rolling can be done in both directions, but production efficiency decreases due to repeated deceleration and acceleration
Solution Approach 1:
By building up a long coil from multiple shorter coils first, the rolling operation can continue for an extended period without stopping, eliminating the repeated deceleration and acceleration that would occur if rolling were performed on individual short coils
3Manufacturing precision
If buildup coil is formed by joining multiple coils, then strip length is enlarged and off-gage rate is reduced, but equipment configuration becomes complex requiring additional winding/unwinding devices
Solution Approach 1:
The first and second winding/unwinding devices perform multiple functions: they handle both the buildup coil formation in the first pass and the reversible rolling in subsequent passes, eliminating the need for a separate buildup-coil winding/unwinding device
4Manufacturing precision
If laser beam welding or flash butt welding is used for joining coils, then high butting accuracy is achieved, but equipment cost increases significantly
Solution Approach 1:
The patent employs a mash seam welding system that uses relatively simple, cost-effective equipment compared to laser beam welding or flash butt welding machines, while still achieving sufficient joining accuracy for the application
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
The proposed method and equipment significantly reduce off-gage rates, enhance production efficiency, and lower initial costs by simplifying the configuration and reducing the need for expensive welding machines, while ensuring high-quality strip thickness and surface finish.
Implementation Method 1
a joining device disposed between the unwinding device and the first winding/unwinding device... a joining step of joining a tail end of the first coil and a leading end of a second coil subsequently unwound from the unwinding device
Implementation Method 2
a first cold rolling mill... a rolling step of guiding a strip of a first coil unwound from the unwinding device directly to the cold rolling mill, rolling the strip
Data Source
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AI summary
Disclosed are cold-rolled material manufacturing equipment and a cold rolling method by which a high efficiency, a high yield and a high investment cost-effectiveness are realized in a small- to medium-scale plant with a capacity of about 300,000 to 600,000 tons of product per year. A strip of a coil 101a unwound from a unwinding device 2 is guided directly to a cold rolling mill 1 to be rolled and then wound onto a winding/unwinding device 4. Upon arrival of the tail end of the coil 101a at a joining device 5, the coil 101a and the leading end of a coil 101b subsequently unwound from the unwinding device 2 are joined. Subsequently, rolling and joining for the coil 101b and following coils are repeated to perform first-pass rolling by the cold rolling mill 1 and joining by the joining device 5, thereby forming a plurality of coils into one buildup coil 102. The buildup coil 102 is subjected to reversible rolling a predetermined number of times until a desired product strip thickness is reached. In the final pass, the buildup coil 102 is cut by a cutting device 6a or 6b, to form a plurality of coils 103.