Tension controls in strip processing lines

Abstract

The problem of tension control in metal-strip processing lines is discussed. A tensioncontrolled zone is considered and the relationships between tension change and motor-speed changes are developed. The effects of placing a number of undriven rolls within the controlled zone are discussed and the associated tension-change state equations and transfer functions are derived. Relationships are developed between the order of the system (or the system gain) and the number offree rolls. The steady state and dynamic accuracy of tension controls are discussed and relationships are produced to allow the calculation of tension-loop gain and static- and dynamic-tension errors. The difficulties associated with the definition of tension-loop gain are also described. This quantity is shown to be dependent on the gain of the tension-error amplifier and the drive-system speed regulation.