USE OF THE GRAPHO-KINEMATIC METHOD IN MACHINING HELICAL GROOVES WITH A DISC TOOL

摘要

Helical grooves (HGs) are very widely used in the parts of machines and tools; the quality of their machining has a significant influence on the operational effectiveness of the articles. The surface of the HG is often machined by a disc cutting tool (CT) (milling cutter, spiral cutting head, grinding wheel) with coordinated motions of the CT and the workpiece. In this case the shaping motions are close to a centroid-free envelope. This machining scheme is characteristic for both the HGs that have large pitch and the helical surfaces with small pitch (threads and worms). The accuracy of the machining of the HG is influenced by a multitude of designer-technological factors. This influence is particularly great in milling the HG with a disc milling cutter or in grinding with a disc wheel. In contrast with spiral cutting and thread grinding, in addition to the profile of the CT and the angle T of its setting relative to the HG (approximately equal to the HG inclination angle), the accuracy of the HG in this case is also influenced by the position of the point S (Fig. 1) of the crossing of the axis of the CT holder and the workpiece axis (this position determines the distances L{sub}1 and L{sub}2) - and also by the interaxis distance a{sub}w.