Milling path planning for helical surface copper electrodes

Abstract

Milling has the characteristics of flexibility and versatility, and can largely reduce the production cycle of customized tools. This study aims to mill helical surfaces of uniform roughness with universal tools in four-axis CNC machine tools through designing the optimal milling path. The transverse profile of the involute gear is modeled by the analytical method and the equidistant profile of the transverse profile is established by using the principle of normal offset to provide a theoretical tool position for tool paths. Aiming at the problem of unequal adjacent line spacing generated in the determination of the number of feed lines based on a constant angle, a determination method of the number of feed lines based on a constant arc length is proposed. In this method, according to the principle of calculus, the arc length of the involute curve is calculated to determine the proper number of feed lines which allows the scallop height to be approximately uniformly distributed on the tooth surface. In milling experiments, the processing efficiencies of LRTSLBL milling and LRTSTBT milling were confirmed and the peak of pitch under a small volume of tool wear was avoided by LRTSLBL milling. Importantly, the skip tooth machining test by LRTSTBT milling confirmed the cause for pitch peak and provided the basis for pitch error compensation.