Compensation of machine tool thermal deformation in spindle axis direction based on decomposition method

One of the fundamental areas in high precision cutting is represented by the machine's thermal state monitoring. Understanding of this state gives significant information about the overall machine condition such as proper performance of cooling system as well as software compensation of machine's thermal deformation during manufacturing. This paper presents a method focused on compensation of machine's thermal deformation in spindle axis direction based on decomposition analysis. The machine decomposition is performed with the help of specially developed measuring frame, which is able to measure deformation of machine column, headstock, spindle and tool simultaneously. Compensation is than calculated as a sum of multinomial regression equations using temperature measurement. New placements of temperature measurement like spindle cooling liquid or workspace are used to improve the accuracy of this calculation. Decomposition process allows describing each machine part's thermal dynamic more precisely than the usual deformation curve usually used one deformation curve for the complete machine. The residual thermal deformation of the machine is considerably reduced with this cheap and effective strategy. The advantage is also in the simplicity of presented method which is clear and can be used also on older machines with slower control systems without strong computing power.

► Compensation of thermal deformation as a fundamental step how to increase machine's accuracy.
► Machine decomposition to analyze thermal behaviour of all important parts of a machine.
► Compensation equation for each part of machine.
► Overall compensation model development based on machine configuration.
► Verification measurement to confirm the model quality.