Abstract: In an arrangement for a tandem cold mill in order to compensate for "speed effect," each stand has a roll force memory unit and an oil film roll force controller unit which operate together, and in conjunction with a tensiometer, to maintain a relatively constant roll gap during the acceleration and deceleration phases of the mill. In threading, in tailing out, and in a full run speed of the mill, the roll force memory unit is constantly operating to obtain a "lock on" roll force reference for the stand prior to the acceleration or deceleration phase. A roll force error signal, which is the difference between a roll force reference of the roll force memory unit and an instantaneous roll force, enters the oil film roll controller. A proportional integrator type controller in the oil film roll force controller unit changes the roll force error signal within a limit of +25% of the desired tension.

Abstract: A method for making delivery gauge corrections at low mill speeds during threading and tailing out of a workpiece by varying the interstand tension of the workpiece. The tension between the last two stands is used with a desired tension and the delivery AGC by tension mode of an existing delivery automatic gauge control (AGC) to change the speed of the downstream stands. During the threading and tailing out phases, the delivery AGC by speed is turned off and set to zero. In the full run phase, the interstand regulators are changed to a tension by roll gap mode, and an existing delivery automatic gauge control (AGC) by speed is used to provide a stand speed reference for the downstream stands. In the full run phase, the delivery (AGC) by tension is turned off an set to zero. In the tailing out phase optionally, the tension between each stand is used in a similar manner to provide a speed reference change for each stand immediately downstream from where a tension controller is located.

Abstract: A digital current control arrangement for optimizing the transport time delay of a thyristor power supply used as a source of armature current for a DC motor utilizes a coarse gate angle interrupt subroutine to perform a preliminary calculation of the gate firing angle for the next thyristor to be fired. The coarse gate angle calculation is performed at a predetermined time following the firing of a previous thyristor. A finite gate angle interrupt subroutine is also provided for recalculating the gate firing angle at a second predetermined time just prior to the firing of the thyristor. The finite and coarse gate angle interrupt subroutines both perform their respective calculations using the common parameters. A flag passing arrangement is also included in the current control arrangement and is effective to insure that the finite gate firing angle is the preferred calculation used in the firing of the next thyristor.