Tapered Work Roll Cold Rolling for Edge Crack Suppression
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Solution Overview
Problem
Existing cold rolling methods fail to sufficiently suppress the occurrence of edge cracks in materials during cold rolling, leading to sheet breakage.
Innovation Solution
A cold rolling method using a rolling mill with tapered work rolls in specific stands, applying a linear load of 0.8 t/mm or more, and setting the tapered rolling portion width within a specific range to control edge drop and tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a method for controlling sheet thickness in the width direction using a rolling mill with shifted and crossed work rolls is employed, then an excellent sheet thickness distribution over the entire sheet width is obtained, but the occurrence of edge cracks during cold rolling cannot be sufficiently suppressed and sheet breakage cannot be sufficiently prevented
Solution Approach 1:
The invention changes the parameter of linear load from the conventional range to 0.8 t/mm or more. This parameter change fundamentally alters the rolling conditions to simultaneously achieve both excellent sheet thickness distribution and sufficient suppression of edge cracks, resolving the technical contradiction between manufacturing precision and reliability
Solution Approach 2:
The invention introduces dynamic control of the tapered rolling portion width WRδ, adjusting it within -50 mm to -5 mm based on rolling conditions. This dynamic adjustment allows the system to adaptively optimize both sheet thickness distribution and edge crack suppression, preventing sheet breakage while maintaining precision
2Reliability
If the linear load is increased to suppress edge cracks, then sheet breakage prevention improves, but the sheet thickness distribution control becomes more difficult
Solution Approach 1:
The invention employs dynamic adjustment of the tapered rolling portion width WRδ within -50 mm to -5 mm to compensate for the increased linear load. This dynamic control mechanism maintains sheet thickness distribution precision even when operating at high linear loads of 0.8 t/mm or more, resolving the contradiction between reliability and manufacturing precision
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 method effectively prevents sheet breakage by significantly suppressing the occurrence of edge cracks, maintaining a suitable edge drop ratio across stands, and reducing edge tension.
Implementation Method 1
the N-th stand rolls the material to be rolled with a linear load of 0.8 t/mm or more
Implementation Method 2
a tapered work roll having a taper formed on an end portion of a roll having a uniform diameter
Data Source
Figure 1~2
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AI summary
A cold rolling method, cold rolling equipment, and a cold-rolled steel sheet manufacturing method capable of preventing sheet breakage by sufficiently suppressing occurrence of an edge crack of a material to be rolled during cold rolling are provided. In the cold rolling method, a rolling mill (2) including a plurality of stands (31) to (34) cold-rolls a material to be rolled (S). An N-th stand (3N) (N is a natural number equal to or greater than 2) arranged in an N-th position from an upstream side of the material to be rolled (S) in a transfer direction among the plurality of stands (31) to (34), includes a tapered work roll (4a1) having a taper (4ab) formed on an end portion of a roll (4aa) having a uniform diameter. The N-th stand (3N) rolls the material to be rolled (S) with a linear load of 0.8 t/mm or more.