Rolling method and rolling mill of strip for reducing edge drop

A rolling method of a strip for continuously rolling the strip on a tandem mill that includes a plurality of stands, each stand having work rolls including an upper work roll and a lower work roll, the method comprising the steps of:

• (a) providing a mechanism for shifting the work rolls with each work roll having a tapered end and a mechanism for crossing the upper work roll and the lower work roll on at least one stand upstream of a final stand to cause the same to serve as a control stand;
• (b) determining a quantity of shift and a crossing angle as quantities of operation necessary for correcting the edge drop of the strip;
• and
• (c) causing the work rolls to shift and cross each other with the determined quantity of shift and crossing angle.

A rolling method of a strip for continuously rolling the strip on a tandem mill comprising a plurality of stands, each stand having work rolls including an upper work roll and a lower work roll, the method comprising the steps of:

• (a) shift controlling the work rolls, with each work roll having a tapered end, in an axial direction and cross controlling the upper and the lower work rolls on at least two of the plurality of stands;
• (b) performing a work roll shift control and a work roll cross control on leading side stands from among the plurality of stands based on a first thickness distribution detected upstream of the leading side stands;
• and
• (c) performing the work roll shift control and the work roll cross control on the leading side stands from among the plurality of stands based on a second thickness distribution detected downstream of trailing side stands.

A tandem rolling mill including a plurality of stands, wherein at least one stand except for a final one is a control stand, each stand having a pair of work rolls with each work roll having a tapered end, the tandem rolling mill comprising:

• (a) a shifting mechanism which causes the pair of work rolls from at least one stand to shift in an axial direction, and a crossing mechanism which causes the rolls to cross each other in a horizontal plane;
• and
• (b) control means which determines a quantity of shift and a crossing angle as quantities of operation necessary for correcting the edge drop of the strip, and
• (c) means for sending the determined quantity of shift and crossing angle to the shifting mechanism and the crossing mechanism to cause the work rolls to shift by the quantity of shift and to cause the work rolls to cross each other at the crossing angle.

A control apparatus for a tandem rolling mill adapted for permitting a thickness control in a width direction of a strip, the tandem rolling mill including a plurality of stands with at least one stand having a shifting mechanism for causing a pair of work rolls with each work roll having a tapered end to shift in an axial direction and a crossing mechanism for causing the work rolls to cross each other within a horizontal plane, the control apparatus comprising:

• (a) means for determining a quantity of shift and a crossing angle as quantities of operation necessary for correcting an edge drop of the strip;
• (b) means for sending the determined quantity of shift and crossing angle to the shifting mechanism and the crossing mechanism, respectively, to cause the work rolls to shift by the quantity of shift and to cross each other by the crossing angle;
• (c) means for detecting a first thickness distribution in a width direction before rolling;
• (d) means for detecting a second thickness distribution in the width direction after rolling;
• (e) means for crossing/shifting control of the rolls of leading side stands based on a first thickness profile derived from the first thickness distribution detected before rolling;
• and
• (f) means for crossing/shifting control of the rolls of trailing side stands based on a second thickness profile derived from the second thickness distribution detected after rolling.