Thermal analysis and compensation of a double-column machining centre

The objective of this work is to enhance the accuracy of a double-column machining centre by compensating thermal errors using software. Characteristics of the thermal errors were analysed by carrying out a sequence of tests. Temperature measurements were carried out with thermocouples. Capacitance probes were used to measure the thermal errors. A multiple linear regression-based technique was applied to correlate the thermal errors to the temperature distribution. The signals of the measured temperatures were sent to a central processing unit board inside a computer numerical controller. The predicted thermal errors, based on the regression model, were sent to the controller for real-time error compensation. Test results show that a 90 per cent reduction in thermal errors has been achieved after compensation.