THERMAL ASYMMETRY ANALYSIS OF MOTORIZED SPINDLES

Abstract

This paper presents a method to quantify and reduce thermal asymmetry of motorized spindles. Thermal asymmetry leads to angular and radial deflections at the tool center point. In contrast to simple thermal expansion issues, these effects are harder to compensate. Therefore, the causes of the asymmetries should preferably be evident in the construction phase. This paper introduces a newly developed mathematical formulation to quantify thermal asymmetry. Thermal asymmetry is observed along the longitudinal axis of a motorized spindle. The formulation quantifies thermal asymmetries as a difference of a geometrical centroid and a newly introduced thermal centroid. For this analysis, several motor spindles with different fluid cooling circulation systems were observed. In order to show the legitimacy of the formulation, the spindle’s calculated thermal asymmetries are compared with their respective radial tool center point displacements. The results show that the asymmetries correlate with the displacements. Furthermore, the quantification of the thermal asymmetry actually allows to locate its causes. In motor spindles the asymmetry is mostly caused by the complex fluid circulation system. The spindle with the worst cooling circulation showed a radial displacement of 26,32 µm. Through thermal asymmetry optimization of the circulation’s heat transfer, the displacement could be reduced to 0,66 µm. The developed method is not limited to motorized spindles. It will be investigated further to develop a generally valid formulation.

Recommended articles

A FLEXIBLE AND ROBUST 3D COORDINATE MEASUREMENT SYSTEM BASED ON WHITE LIGHT INTERFEROMETRY FOR DEVIATION MEASUREMENTS ON SWISS-TYPE TURNING MACHINES

H.-W. Lahmann, S. Schmalzried, G. Ketterer, D. Weber, F. Welzel, D. Jeyara
Keywords: 3D measurement | Optical Measuring | Interferometry | Machine Calibration | Thermal Deviation

THERMAL STIFFNESS – A KEY ACCURACY INDICATOR OF MACHINE TOOLS

A. P. Kuznetsov, H. J. Koriath
Keywords: Machine tool | thermo-physical model | thermoelasticity | thermal stiffness | accuracy indicator

SMART SENSOR FOR ENHANCEMENT OF A MULTI-SPINDLE AUTOMATIC LATHE THERMAL ERROR COMPENSATION MODEL

O. Horejs, M. Mares, A. Mlcoch
Keywords: Smart sensor | Multi-spindle automatic lathe | thermal error | industry 4.0 | accuracy | Compensation

HIGHLY RESPONSIVE AND ACCURATE TEMPERATURE MEASUREMENTS IN ORTHOGONAL CUTTING THROUGH INNOVATIVE SINGLE LEG THERMOCOUPLE

I. Hamm, F. Rossi, G. Poulachon, B. Marcon, H. Birembaux, N. Maury, S. Valadon, F. Labarthe
Keywords: temperature measurement | Ti-6Al-4V | orthogonal cutting | Heating rate