Rolling mill control for tandem rolling

Claim 1

A method of operating a rolling mill to roll metal strip wherein said mill has a plurality of rolling mill stands arranged in tandem, and wherein further, the first and last stands of said mill are provided with hydraulic means for controlling the rolling load upon said stands, said method comprising the steps of: obtaining a first signal representing the product of the velocity and gauge of said metal strip entering said first stand; obtaining a second signal representing the product of the desired exit speed and the desired exit gauge of said metal strip leaving said last stand of said mill; obtaining a third signal representing the actual exit speed of said metal strip leaving said last stand of said mill; comparing said first and second signals and employing the difference, if any, between said first and second signals to adjust said hydraulic means upon said first stand in the sense so as to reduce said difference substantially to zero whereby the entry mass flow of said metal strip will equal the desired exit mass flow of said metal strip; and comparing said third signal with a fourth signal representing said desired exit speed of said metal strip leaving said last stand and employing the difference, if any, between said third and fourth signals to control the load upon said last stand in the sense so as to reduce said difference substantially to zero whereby said actual exit speed is maintained substantially equal to said desired exit speed and, in turn, the actual exit mass flow of said metal strip is substantially equal to said entry and desired exit mass flows of said metal strip.

Claim 2

A method of operating a rolling mill to roll metal strip wherein said mill has a plurality of rolling mill stands arranged in tandem, and wherein further, the first and last stands of said mill are provided with hydraulic means for controlling the rolling load upon said stands, said method comprising the steps of: obtaining a first signal representing the product of the velocity and gauge of said metal strip entering said first stand; obtaining a second signal representing the product of the desired exit speed and the desired exit gauge of said metal strip leaving said last stand of said mill; obtaining a third signal representing the actual exit speed of said metal strip leaving said last stand of said mill; comparing said first and second signals and employing the difference, if any, between said first and second signals to adjust said hydraulic means upon said first stand in the sense so as to reduce said difference substantially to zero whereby the entry mass flow of said metal strip will equal the desired exit mass flow of said metal strip; and comparing said third signal with a fourth signal representing said desired exit speed of said metal strip leaving said last stand and employing the difference, if any, between said third and fourth signals to control the load upon said last stand in the sense so as to reduce said difference substantially to zero whereby said actual exit speed is maintained substantially equal to said desired exit speed and, in turn, the actual exit mass flow of said metal strip is substantially equal to said entry and desired exit mass flows of said metal strip.