Effect of Heat Generated in Guiding of Machining Center on Thermal Deformation Behavior in Linear Feed Axis Operation and Investigation of Its Reduction Method

Abstract

The effects of internal and external heat generation on machine tools cause thermal deformation to lead to the reduction of machining accuracy. The internal heat generation on spindle, ball screws or motors has been studied and proposed the countermeasures in many reports. However, the heat generation by guiding is not studied enough so far. The demand for machining accuracy in machine tools are still getting higher, then we need to consider the effects of heat generation by guiding. In this study, using the 3-axis vertical type machining center that has the hybrid guiding system (with sliding and rolling elements), the temperature changes and the relative displacement between the spindle and the table are measured. By FEM based on the temperature change data, the thermal deformation is estimated. Then, the effects of heat generation by guiding are investigated and suggested the countermeasures on FEM. The results obtained in the study are as follows, (1) The simulation results based on the experimental data give close agreement with the experimental results. (2) Even if the heat generation of driving system can be suppressed, a certain level of relative displacement might be remained. In some cases, the relative displacement without the heat generation of the driving system is even greater than or equal to that with the heat generation. (3) The countermeasure that the effect of cooling of the guide rail or its circumference on the thermal deformations is simulated and the possibility that can decrease the thermal displacement is suggested.