Thermal behavior of a machine tool equipped with linear motors

Development of a feed drive system with high speed and accuracy has been a major issue in the machine tool industry. Linear motors can be used as efficient tool to achieve the high speed and accuracy. However, a high speed feed drive system with linear motors, in turn, can generate heat problems. Also, frictional heat is produced at the ball or roller bearing of LM block when driven at high speed. It can affect the thermal deformation of the linear scale as well as that of the machine tool structure.In this paper, important heat sources and resulting thermal errors in a machine tool equipped with linear motors were investigated when it was operated at high speed. The thermal deformation characteristics were identified through measuring the thermal error caused from thermal deformation of the linear scale and the machine tool structure. The dominant thermal error components were identified from the thermal error analysis using finite element method. It was shown that the proposed analysis scheme is efficient in identifying the dominant thermal error components and its magnitudes such as the thermal expansion and movement of the linear scale, thermal deformation of the machine tool slide.