Efficient trochoidal milling based on medial axis transformation and inscribed ellipse

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ORIGINAL ARTICLE

Efficient trochoidal milling based on medial axis transformation and inscribed ellipse Xi Huang 1,2 & Shijing Wu 1 & Liang Liang 1 & Xiaoyong Li 1 & Nuodi Huang 3 Received: 22 June 2020 / Accepted: 24 September 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020

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. Keywords Trochoidal toolpath . 2D pocket . Media axis transformation . Elliptical curve . Machining efficiency

1 Introduction High-speed machining is widely used as effective technology for its good performances including high surface quality, low tool wear, and high efficiency. To satisfy the machining quality and efficiency demands, a series of new strategies have been proposed, for example, spiral tool path [1, 2], trochoidal tool path [3, 4], and plunge milling toolpath [5, 6]. Compared with other machining strategies, trochoidal milling has great advantages on chip evacuation and tool cooling. Moreover, the limitation of engagement angle between the cutter and

* Nuodi Huang [email protected] 1

Hubei Key Laboratory of Waterjet Theory and New Technology, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China

2

State Key Laboratory of Digital Manufacturing and Equipment Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

3

State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

workpiece to prevent large cutting force fluctuation leads to longer tool life and less tool wear. Conventional trochoidal toolpath is a combination of circular motions with linear morphing transitions. Influences of machining parameters on cutting force and dynamics have been studied by various papers. Otkur et al. [7] established an analytical model for engagement angle, and then a numerical force model was proposed t