Developing a Digital Control System for Cutting a Moving Strip to Length

This paper dwells upon crank-type flying shears installed on profile benders at a steelwork facility. It analyzes a control system that enables the unit to cut a continuously rolling strip to length. The research goal is to improve the precision of cutting profiled sheets to length, to reduce the production of out-of-tolerance workpieces, and to increase the unit’s throughput. The report addresses methods to improve the precision of cutting workpieces to length in static and dynamic operation. It proposes a concept solution for generating and communicating control signals to the flying shear motor drive; the signals are a function of the strip speed adjusted for the dynamic parameters of the motor. The paper further substantiates a redesign of the shears, which does not involve replacing the power unit. The research team developed a dynamic model for the tested object, which helps analyze the control system for cutting to length. Thus, the team was able to derive the number of the preemptive pulses of the strip position sensor as a function of the strip speed. We then created a two-level automated system for controlled cutting to length, which is based on a microprocessor unit and an industrial controller. A control program has been developed and implemented. After experimental testing was done, the system was put into operation.