Cold Rolling Tension Control for Wrinkle-Free Thin Steel Sheet
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Solution Overview
Problem
Existing cold rolling methods for producing thin cold-rolled steel sheets often result in wrinkles, which are difficult to prevent without modifying the mill equipment, thereby increasing costs.
Innovation Solution
A cold rolling method that controls the steel sheet unit tension in the initial stage of rolling and adjusts the front end sheet thickness to prevent wrinkles, without requiring modifications to the mill equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wrinkle-preventing roll is installed in the mill to prevent wrinkles during cold rolling of thin steel sheets, then wrinkle prevention is improved, but equipment cost and mill modification requirements increase
Solution Approach 1:
The invention changes the tension parameter during the initial stage of rolling to be lower than the steady-state rolling tension. Specifically, the unit tension in the initial stage is controlled to be 0.7-0.95 times the steady-state rolling unit tension, which prevents wrinkles without requiring any physical modification to the mill equipment
Solution Approach 2:
The invention applies preliminary tension control during the initial stage of rolling (when the steel sheet first enters the rolling pass) to prevent wrinkle formation before the rolling process completes. By controlling tension in this critical initial period, the steel sheet is prevented from developing wrinkles that would require additional equipment to correct
2Reliability
If the steel sheet unit tension during steady-state rolling is reduced to prevent wrinkles, then wrinkle prevention is improved, but rolling control complexity increases
Solution Approach 1:
The rolling process is segmented into two distinct stages: an initial stage and a steady-state rolling stage. Each stage has different tension control requirements, with the initial stage using reduced tension (0.7-0.95 times steady-state tension) and the steady-state stage using normal tension. This segmentation allows wrinkle prevention without compromising the overall rolling control
Solution Approach 2:
The tension control is made dynamic by adjusting the unit tension based on the rolling stage. The system automatically transitions from lower tension during the initial stage to higher steady-state tension, creating a dynamic control strategy that prevents wrinkles while maintaining simple overall control logic
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 method effectively prevents wrinkles during cold rolling, thereby improving the production yield rate of cold-rolled steel sheets, even for thin sheets with thicknesses of 0.10 mm or less.
Implementation Method 1
the steel sheet unit tension N1 during steady-state rolling exceeds the reference unit tension N0
Implementation Method 2
rolling a steel sheet in multiple rolling passes using a cold mill
Implementation Method 3
cold rolling method of rolling a steel sheet in multiple rolling passes
Data Source
AI summary
Provided is a cold rolling method by which the occurrence of wrinkles during cold rolling can be prevented without having to modify a mill. A cold rolling method of rolling a steel sheet in multiple rolling passes using a cold mill, the method including when the steel sheet unit tension N1 during steady-state rolling exceeds the reference unit tension N0 in a specific rolling pass in which the target sheet thickness t0 on an exit side of the rolling pass is less than or equal to a reference sheet thickness, controlling the steel sheet unit tension N2 in an initial stage of rolling on an entry side of the specific rolling pass to be less than the reference unit tension N0 and less than the steel sheet unit tension N1 during the steady-state rolling, the reference unit tension N0 is calculated by the formula (1): N0=(150/9)t0+27.1.