Reversible Cold Rolling With Even Passes to Cut Off-Gauge Strip
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Solution Overview
Problem
Current cold rolling mills face challenges in flexibility and productivity, particularly when upgrading from single stand to twin stand or tandem mills, with existing solutions requiring lengthy shutdowns and high costs, and inefficiencies in reducing off-gauge lengths leading to unnecessary pup coil disposal.
Innovation Solution
An improved rolling method for reversible cold mills involving two stands with an even number of passes, utilizing different gear ratios, motor characteristics, and roll roughness, and reduced oil concentration to achieve continuous coil threading and winding, minimizing off-gauge product and enabling more efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single stand reversing mill is upgraded to a twin stand or tandem mill to increase production capacity, then annual production capacity is improved, but shutdown time and conversion cost increase significantly
Solution Approach 1:
The system dynamically switches between single-stand and twin-stand operating modes by selectively engaging or disengaging the second rolling stand. This allows the mill to adapt its capacity to match production requirements without physical reconfiguration, eliminating the need for lengthy shutdowns during upgrades.
Solution Approach 2:
The second rolling stand is designed with multi-functionality, serving as an auxiliary stand when not fully engaged. It can operate in partial capacity modes, allowing the mill to function effectively as either a single-stand or twin-stand configuration, providing universal adaptability across different production phases.
2Loss of substance
If conventional rolling methods are used with odd number of passes, then off-gauge length is reduced, but pup coil disposal is required leading to loss of material and time
Solution Approach 1:
The method ensures continuous useful action by always using an even number of passes, which guarantees that the strip exits at the same end it entered. This eliminates the need to stop for pup coil disposal and rethreading, maintaining continuous production flow and maximizing productivity while minimizing material loss.
3Ease of manufacture
If twin stand mill is used instead of two single stand mills, then investment cost and operative cost are reduced, but equipment complexity increases
Solution Approach 1:
The twin stand mill is designed with modular segmentation, where each stand can be independently controlled and adjusted. This modular approach simplifies the overall system complexity by allowing independent optimization of each stand while maintaining cost efficiency, rather than requiring a fully integrated complex system.
Data Source
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AI summary
An improved rolling method of a metal strip in a reversible rolling mill (1),said reversible rolling mill (1) comprising : -at least one rolling stand (2); -an uncoiling device or pay-off reel (3) and a first recoiling device or entry tension reel (4) on a first side or entry side of the stand (2); -a second recoiling device or delivery tension reel (5) on a second side or delivery side of the stand (2); wherein the reversible rolling mill (1) is run with an even-number of rolling passes strategy, that is according to a method in which a rolling sequence normally carried out in N passes (N integer, odd),each with a given reduction rate is replaced by a rolling in N+1 passes (N+1 integer, even), or in N-1 passes (N- integer ≠ 0, even), the individual reduction rates being calculated to provide in all the same reduction rate as with N passes, the even number of passes inducing 1 that the first side of the stand (2) serves as both sides, entry side and delivery side, of the rolled strip.