Centering spindle for a machine tool including an isolation spacer

Abstract

A centering spindle for use with a workpiece which is to be induction hardened includes a generally cylindrical outer housing into which a shaft is positioned and mounted in spaced relation to the housing by a bearing arrangement. The bearing arrangement allows the shaft to rotate relative to the housing. The end of the shaft extending out of the housing is connected to an isolation spacer which is fabricated out of an electrical insulator material. The isolation spacer in turn is attached to a removable tip which is constructed and arranged for interfacing with the workpiece to be induction hardened. The design of the centering spindle is such that the tip may be removed and replaced when it becomes worn without the need to replace any of the other parts or components of the centering spindle. Further, any electromagnetic field induced in the workpiece and transmitted to the tip will not be transmitted to the shaft nor to the bearing arrangement due to the isolation spacer. Additionally, any substantially elevated temperature which is experienced by the tip due to the heating of the workpiece will be insulated to some extent from reaching the shaft due to the thermal insulation properties of the material used for the isolation spacer.