Efficient trochoidal milling based on medial axis transformation and inscribed ellipse

Abstract

Trochoidal milling is a promising strategy for machining pockets with difficult-to-cut materials. Conventional trochoidal toolpath is composed of a set of circular curves and transition curves. However, the actual radial cutting width has a large variation along processing path due to geometric features of inscribed circles, which results in large fluctuation of cutting width and low material removal rate. In this paper, a new trochoidal toolpath based on elliptical curve is proposed to overcome the mentioned drawbacks. Medial axis transformation is adopted to represent the 2D pocket geometry. An algorithm is developed to determine a sequence of inscribed ellipses according to pre-defined machining parameters. Hermit curve is utilized to generate the transition curves between two adjacent elliptical curves. The overall toolpath length is significantly reduced. Machining experiments are conducted to validate the feasibility and efficiency of the proposed method. The experimental results showed an improvement of 12.7% in machining efficiency without increasing the maximum cutting force, compared with conventional trochoidal toolpath.