Contour machining

Abstract

Abstract The disclosure relates to techniques in equipment for the machining with single point tooling of non-circular shapes and contours. The procedure according to the invention involves the use of a rotary cutting head, carrying one or more cutting tools, arranged to be advanced axially to accomplish internal boring or external turning of non-circular shapes. The cutting head, which may be considered either a boring head or a turning head, depending on whether the cut is taken internally or externally, is mounted for controlled advancing and retracting movements along its rotational axis. The cutting tools themselves, which are carried by the cutting head, are mounted for controlled radial extending and retracting movements as a function of the rotational position of the spindle. The extending and retracting movements of the cutting tool or tools is controlled by means of a pre-shaped contour cam mounted in fixed relation to the workpiece. During each rotation of the spindle, the cutting tools are extended and retracted according to the pattern of the contour cam, resulting in a contoured, non-circular, cutting or boring of the workpiece. Because the tool-carrying spindle rotates, while the work remains stationary, the centrifugal force created by the spindle rotation is used to great advantage to assist in controlling movement of the tool slide in accordance with the path determined by the contour cam. The process and apparatus of the invention can be utilized to outstanding advantage in connection with the machining of epitrochoidal chambers for rotary combustion (e.g., Wankel) engines. Significant process aspects of the invention are directed to that end. In this connection, the invention involves the two-stage machining of an epitrochoidal chamber, with the spindle axis of the machine offset a predetermined distance from the plane dividing the two principal lobes of the chamber. In accordance with an important aspect of the invention, by offsetting the spindle axis along the major axis of the chamber, to be located a short, predetermined distance from the transverse dividing plane, an entire half of the epitrochoidal chamber may be machined in one pass of the spindle, using single point cutting tools. The spindle axis is then symmetrically repositioned in offset relation on the opposite side of the dividing plane, to effect machining in a single pass of the other half of the chamber. This extraordinary technique permits exceptional time economies to be realized in the machining of the combustion chamber while at the same time achieving much greater levels of accuracy than has been obtainable with conventional machining processes.

Inventors

• 👤 A Tomenceak

Bibliographic Details