Method for rolling on-gauge head and tail ends of a workpiece

A method for rolling on gauge material in the head end and tail end of a ferrous or non-ferrous workpiece such as strip or sheet travelling through several stands of a tandem cold mill, the steps comprising:

• in at least the threading and tailing out process of said mill,
• sensing the actual tension in the workpiece between the last two stands of said mill,
• sensing and measuring the delivery gauge thickness of said workpiece at the exit end of the last stand of the mill, and producing a delivery gauge error signal,
• energizing and operating only a delivery automatic gauge control by tension controller while non-energizing a delivery automatic gauge control by speed controller,
• employing said delivery gauge error signal to initiate operation of said delivery automatic gauge control by tension controller,
• combining the output from said delivery automatic gauge control by tension controller with a desired preset tension value and said actual tension value to produce a tension error output,
• employing said tension error output as being representative of a change in speed reference, and
• supplying said change in speed reference to the speed regulator of each of the downstream stands relative to the last stand to drive the rolls of each downstream stand at a speed such as to vary the interstand tension in the workpiece to effect a gauge correction to obtain said on gauge material in the head end and in the tail end of the workpiece in said threading and tailing out processes.

A method for rolling an on gauge thickness in at least the head end of a ferrous or non-ferrous workpiece such as strip or sheet travelling through several stands of a tandem cold mill, said stands each having driven work rolls which define a roll gap, the steps comprising:

• in at least the threading process of said mill,
• sensing the actual tension in the workpiece between the last two stands of said mill,
• sensing and measuring the delivery gauge thickness of said workpiece at the exit end of the last stand of said mill, and producing a delivery gauge error signal,
• energizing and operating only a delivery automatic gauge control by tension controller, while non-energizing a delivery automatic gauge control by speed controller,
• employing the delivery gauge error signal to initiate operation of said delivery automatic gauge control by tension controller to produce an output value,
• combining the output from said delivery automatic gauge control by tension controller with a desired preset tension value and said actual tension value to produce a tension error output,
• employing said tension error output as being representative of a change in speed reference, and
• supplying said change in speed reference to the speed regulator of each downstream stand relative to the last stand to drive the rolls of each downstream stand at a speed such as to vary the interstand tension in the workpiece to effect a gauge correction to obtain said on gauge thickness in the head end of said workpiece in said threading process.

A method for rolling an on gauge thickness in at least the head end of a ferrous or non-ferrous workpiece such as a strip or sheet travelling through several stands of a tandem cold mill, said stands each having driven work rolls which define a roll gap, the steps comprising:

• in the tailing out process of said mill,
• energizing and operating only a delivery automatic gauge control by tension controller while a delivery automatic gauge control by speed controller system in said mill is deactivated,
• sensing the actual tension in the workpiece between said each stands of said mill,
• sensing the delivery gauge thickness of said workpiece at the exit end of the last stand of said mill, and producing a delivery gauge error signal,
• employing the delivery gauge to initiate operation of said delivery gauge automatic gauge control by tension controller to produce an output value,
• combining the output from said delivery automatic gauge control by tension controller with a preset desired tension value for the workpiece between two neighboring stands and the actual tension in said workpiece between said two neighboring stands to produce a tension error output,
• employing said tension error output for said two neighboring stands as being representative of a change in speed reference, and
• supplying said change in speed reference to the speed regulator of each downstream stand relative to the location from which the actual tension in the workpiece is being sensed in order to drive the work rolls of said each downstream stand at a speed to vary the interstand tension in the workpiece to effect a gauge correction to obtain said on gauge thickness in the tail end of said workpiece in said tailing out process.

A method for rolling on gauge material in the head end and the tail end of a ferrous or non-ferrous workpiece such as travelling through several stands of a tandem cold mill, each stand having two work rolls defining a roll gap, the steps comprising:

• in the threading phase of said mill,
• employing a tension by speed mode for the interstand tension regulators, and using a tension controller between the last two stands of the mill to receive input from a tension measuring device representative of the actual tension in said workpiece between said two last stands,
• providing a desired tension input to said tension controller,
• measuring the delivery gauge thickness of said workpiece at the exit end of the last stand of said mill by a delivery gauge sensor and producing a delivery gauge error signal,
• energizing and operating only a delivery automatic gauge control by tension controller which is activated by said delivery gauge error signal and generating and sending an output from said automatic gauge control by tension controller to said tension controller between said last two stands, while allowing a delivery automatic gauge control by speed controller to remain deactivated,
• in said tension controller between said last two stands comparing said actual tension in said workpiece between said last two stands to said desired tension input and summing the tension difference with said output from said delivery automatic gauge control by tension controller to produce a tension error output, and
• sending this tension error signal to only each of the downstream stands relative to the last stand to change the speed of only each of the downstream stands relative to said last stand at the same rate by using said tension error output as a stand speed reference to vary the interstand tension in the workpiece to effect a gauge correction to obtain said on gauge material in said head end of said workpiece, and at the same time causing said tension controller to send no tension error signal to said last stand.