Study on the Geometrical Accuracy in Surface Grinding. Thermal Deformation of Workpiece in Traverse Grinding.

Abstract

Thermal deformation of a workpiece attracted by a magnetic chuck in traverse grinding is theoretically investigated by a finite element method. The results are compared with the measured profiles of ground surfaces. Necessary force of a magnetic chuck to constrain the warp of workpiece bottom surface is also computed. The main results are as follows:(1) Central part of the workpiece bottom surface separates from the magnetic chuck by the thermal stress due to the grinding heat. (2) The local thermal deformation at the central part of a workpiece increases with the number of grinding passes. Around the entrance and exit part of each grinding pass, the local thermal bending deformation occurs. (3) The separation of the workpiece bottom surface and the local thermal deformation lead to a concave profile of the ground surface. (4) When a workpiece of 10×60×40(mm) in dimension is ground under a condition of 10 μm down feed and 5mm cross feed per a pass, the necessary constraining force is about 12MPa.