Configuration-Space Searching and Optimizing Tool Orientations for 5-Axis Machining

This paper presents a methodology and algorithms of optimizing and smoothing the tool orientation control for 5-axis sculptured surface machining. A searching method in the machining configuration space (C-space) is proposed to find the optimal tool orientation by considering the local gouging, rear gouging and global tool collision in machining. Based on the machined surface error analysis, a boundary search method is developed first to find a set of feasible tool orientations in the C-space to eliminate gouging and collision. By using the minimum cusp height as the objective function, we first determine the locally optimal tool orientation in the C-space to minimize the machined surface error. Considering the adjacent part geometry and the alternative feasible tool orientations in the C-space, tool orientations are then globally optimized and smoothed to minimize the dramatic change of tool orientation during machining. The developed method can be used to automate the planning and programming of tool path generation for high performance 5-axis sculptured surface machining. Computer implementation and examples are also provided in the paper.

Interference-free tool orientation determination by a virtual enveloping element for five-axis machining of a freeform surface

In machining freeform surfaces on five-axis machine tools, it is very important to determine the location of the cutting tool. The commercial computer aided design/manufacturing (CAD/CAM) software for five-axis machining often lacks flexibility to specify the appropriate tool orientation and toolpath for surface machining. This paper presents a new methodology for determining feasible tool orientation of a toroidal milling cutter with collision and gouging avoidance in five-axis machining of a freeform surface. To avoid collision and rear gouging, a virtual enveloping element is proposed that is derived from the properties of the local and global surfaces. The set of tool orientations can be found first by confining the cutting tool within the virtual enveloping element. Then, the principal induced normal curvatures between the freeform surface and the cutting tool need to be evaluated to offer the criterion of gouging detection. To achieve the best combination of scallop height and machining efficiency, the contact length is also calculated for various tool orientations. The toolpaths generated by the proposed method are verified through solid cutting simulation and a trial cut on a five-axis machine.

Admissible Tool Orientation Control of 5-Axis Complex Surface Machining for CAD/CAM Systems

This paper presents a methodology and algorithms of admissible tool orientation control for gouging avoidance in 5-axis machining. A method is proposed to find the admissible tool orientation by considering both local and global surface shapes. A filleted endmill is used in this study for 5-axis machining. Based on the evaluation of local surface shape, a geometry analysis method is developed to first find a feasible tool orientation for gouging avoidance along two orthogonal cutting planes. Adjacent geometry is then taken into consideration for detecting possible rear gouging. A localization algorithm is developed for filleted endmills to identify potential rear gouging area. Both the circular approximation and the detailed gouging checking methods are proposed for rear gouging correction. The techniques presented in this paper can be used to eliminate errors of tool paths as they are generated. Unlike the traditional graphical verification and user-interactive correction of tool path generation, the proposed methodology can be used to automate the planning and programming of cutter path generation for 5-axis machining.