Improvement in the working accuracy of an nc lathe by compensating for thermal expansion

Abstract

This study proposes a practical and economical way of improving the working accuracy of an nc lathe by predicting and compensating for the thermal expansion of the tool during machining, a phenomenon which greatly affects the machining accuracy. The thermal expansion can be calculated accurately by the program in which the amount of heat generation is represented as a function of cutting condition and cutting time. As the program judges that the expansion of the tool exceeds or falls below a certain value, tool offsets are made in the direction of cut in advance of operation. Cutting tests on an nc lathe with this compensation have shown a marked improvement in the machining accuracy