Automatic velocity control in cutting-off machines

Abstract

Usually, automatic cutting-off machines, of metallic pipes or bars, use constant cutting velocity. This mode of operation, constant cutting velocity combined with different profiles of materials to be cut, causes variable cutting forces to be applied to the saw. As a result, the cutting off machine is generally set for the worst expected conditions, otherwise excessive wear of the saw and machine will occur. Further, traditional cutting-off machines require adjustments to be made in order to automatically detect the completion of a cut. The objective of this project is the study of the application of control algorithms to the process of cutting-off metallic pipes or bars, with variable profiles, implemented in an industrial cutting-off machine, commercially available. The testes algorithms concern real-time cutting control and automatic detection of cut completion. The algorithms are implemented in a low cost programmable logic controller (PLC), allowing its adoption in industrial applications without significant increase on machine cost. All algorithms were developed having in mind safety issues relative to the operation of the cutting machine in order to prevent damage to the machine itself. Also, all process related relevant parameters are monitored on a personal computer using OPC (object linking and embedding-for process control).