A temperature control system for laser welding of plastics differing in optical parameters

This article describes a specially developed system for automatic control of temperature in the weld area during lap welding. The major aim of the system is to hold the required temperature constant while joining two plastic materials differing in optical properties, where one part is transparent to the laser radiation and the other absorbs it. The system uses a real-time reconfigurable National Instruments CompactRio controller featuring conditioned input-output modules. The control application, based on fuzzy logic control, was created using LabVIEW software. A sampling rate of 1kHz was employed. The feedback signal is derived from an optical pyrometer, which measures the temperature in the fusion zone. The study involved empirically determining the optimal settings and testing the controller performance. The article includes waveform data concerning the process variable, the control signal and the error signal.