Evaluation of workpiece orientation and configuration of multi-axis machine tool using visibility cone analysis

Abstract

Multi-axis machining of a complex surface is not only efficient but also reduces workpiece set-up errors. However, engineers usually rely on experience when determining set-up orientation and often cannot finish complex surfaces in one set-up. In this paper, a rational evaluation method for workpiece orientation and configuration of machine tool before tool path planning is proposed to increase the efficiency and reliability of process planning.By incorporating the visibility cone into workspace analysis, a software module is constructed in this research for optimum workpiece orientation and configuration of machine tool. First, the configurations of three-, four-and fiveaxis machine tools were synthesised, and the workspace was then analysed using form-shaping function. Both position vector and normal vector of each point along the u and v directions in the machining surface were employed to calculate the visibility range as the point of the visibility cone. In 3-axis machining, all normal vectors of the surface were projected on a unit sphere. All normal vectors were ensured to be within the visibility range of the ballmill cutter as the workpiece set-up orientation changed. In 4-axis machining, the intersection between the visibility cone of each point and the workspace was obtained by changing the set-up orientation. In 5-axis machining, according to different workspaces of 5-axis machine tools, the visibility range of the machining surface was determined to yield the intersection between the visibility cone and the workspace by changing the workpiece orientation.The proposed method for evaluating manufacturability has been demonstrated to generate optimum workpiece set-up orientation and the suitable configuration of machine tools. Tool interference with workpiece surface can be avoided, which can help improve the planning of tool path.

Optimization of the setup position of a workpiece for five-axis machining to reduce machining time

“…Some researchers studied the effects of the orientation of a workpiece on planning the toolpath. Lee et al 8 determined the optimal workpiece orientation by the minimum rotary movement. Hu et al 9 determined the optimal setup by the largest intersection of the visibility maps.…”

“…To find the pseudo-distance, first, we derived the 4 4 homogeneous transformation matrix T i and S i with different kinematics of machine with the rotary angles A and C according to the steps in section 2.1. The general form of the transformation matrices can be represented as equations (8) and (9). We defined 3 3 matrices, R Ti and R Si , as the rotary matrices, and 3 1 matrices, L Ti and L Si , as the translation matrices in T i and S i , respectively.…”

Particle swarm optimisation (PSO)-based tool path planning for 5-axis flank milling accelerated by graphics processing unit (GPU)

“…It is commonly used in the manufacture of aerospace, automobile, energy, and mold parts. First, the tool must be properly posed in 3D space with the rotational degrees of freedom in order to avoid any unexpected collisions (Lee et al 2010). There are mainly two milling methods in 5-axis machining.…”

A morphology proposal in commercial-off-the-shelf reconfigurable machine tools

“…In this work, the authors use a specific library of parts. Lee et al (2010) have developed a method to configure multi-axis machines in the machining of conical surfaces but no structural transitions between different DOF are investigated in detail. A polychromatic approach is also used in the generation of machine tools by Xu et al (2005); they envisage that this technique will be useful in process planning using decision support systems.…”