Title

AN ANALYSIS OF TEMPER MILLS IN HEAVY GAUGE LEVELING / CUT-TO-LENGTH LINES

AN ANALYSIS OF TEMPER MILLS IN HEAVY GAUGE LEVELING / CUT-TO-LENGTH LINES

Authorship

Zip., Mark E.

Zip., Mark E.

I am this author

DOI

10.5151/2594-5297-22633

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Abstract

Heavy gauge flat plate formed from coils of hot rolled low carbon and mild steels is formed by powered roller levelers. The leveler adjusts the strain pattern by progressively counter-bending the strip over a series of rolls. The bending forms tensile stresses (non-contacting surface) and compressive stresses (surface in contact with the roll). The finite depth of yielding stress penetration leaves a nonyielded interior that retains the stress pattern of the incoming coil (residual). A flat plate is produced by balancing the plate’s adjacent, coupled interior stresses (including residuals) so the composite stress pattern falls below the buckling threshold. Cutting the plate separates the coupled interior stresses leading to the pieces deflecting out of plane to find a new equilibrium. The nature of the incoming transverse strain pattern may cause some regions of the plate width to not experience sufficient yielding stress leading to Lüder Bands in low carbon steels. This paper examines the performance improvements of placing an in-line temper mill upstream of the leveler. The temper mill induces a full depth plastic deformation that leaves no residual stress pattern from the incoming coil, and yields the material well beyond the Lüder Band region. The temper mill can prepare the shape of the strip fed to the leveler, optimizing the leveler’s bending adjustments and tracking.

Heavy gauge flat plate formed from coils of hot rolled low carbon and mild steels is formed by powered roller levelers. The leveler adjusts the strain pattern by progressively counter-bending the strip over a series of rolls. The bending forms tensile stresses (non-contacting surface) and compressive stresses (surface in contact with the roll). The finite depth of yielding stress penetration leaves a nonyielded interior that retains the stress pattern of the incoming coil (residual). A flat plate is produced by balancing the plate’s adjacent, coupled interior stresses (including residuals) so the composite stress pattern falls below the buckling threshold. Cutting the plate separates the coupled interior stresses leading to the pieces deflecting out of plane to find a new equilibrium. The nature of the incoming transverse strain pattern may cause some regions of the plate width to not experience sufficient yielding stress leading to Lüder Bands in low carbon steels. This paper examines the performance improvements of placing an in-line temper mill upstream of the leveler. The temper mill induces a full depth plastic deformation that leaves no residual stress pattern from the incoming coil, and yields the material well beyond the Lüder Band region. The temper mill can prepare the shape of the strip fed to the leveler, optimizing the leveler’s bending adjustments and tracking.

Keywords

Temper mill; Heavy gauge strip; Leveling; Cut-to-length.

Temper mill; Heavy gauge strip; Leveling; Cut-to-length.