Extension of the Torque Limit Skip Method to Multi-Spindle Thermal Error Compensation

Divíšek, D.; Kaftan, P.; Mayr, J.; Bambach, M.; Wegener, K. In: 4th International Conference on Thermal Issues in Machine Tools (ICTIMT2025). Cham: Springer, 2026. p. 287-296. ISSN 2194-0525. ISBN 978-3-032-01193-0.

This paper introduces an extension of the thermal error compensation based on the Torque Limit Skip (TLS) to two independent spindle systems of a multi-spindle Swiss-type lathe. The TLS method is a recently introduced approach for the measurement and compensation of thermal errors of precision machine tools. Until now, this method had been used for probing at a single location and to create a single compensation model, specifically on the main spindle of a Swiss-type lathe. The challenge of a second counter-spindle system is that it introduces a second tool-center-point into the working space, the thermal behaviour of which is different compared to that on the main spindle. Furthermore, on Swiss-type lathes, there is no possibility to measure with a movable touch-trigger probe or displacement sen-sors. This work therefore extends the TLS compensation to the counter-spindle, by devising a second probing location and implementing a second compensation model. It is demonstrated that the two measurement cycles and compensation mod-els can run independently and that each model can compensate the thermal errors of its corresponding spindle system. Results show that with out-of-sync operation of the two spindles, the TLS measured thermal errors are reduced by 80% when using a compensation model based on transfer functions.