Rolling ball method applied to 3½½-axis machining for tool orientation and positioning and path planning

Abstract

In 3½½-axis machining, the machined part surface is partitioned in pre-processing in order to calculate the tool position and patch boundaries and then machined in patches, thereby minimizing the intermediate manual part re-positioning and the overall machining time. Each patch requires a constant, but different, tool orientation. In previous research, local properties have been used to subdivide surfaces into patches. For an ideal tool position and orientation, however, the tool's shape and curvature should exactly match the shape and curvature of the part surface. The rolling ball method, originally developed for 5-axis machining, considers the regional characteristics of tool positioning. This work extends the rolling ball method to 3½½-axis machining, thereby successfully delivering 5-axis quality with currently installed 3-axis computer numerical control milling machines. The pseudo-radius of curvature provides a novel geometrical subdivision criterion. Two Bézier curved surfaces are tested and compared with the 5-axis rolling ball method. Two additional surfaces are presented to further demonstrate the partitioning capability of the method. The results suggest that the rolling ball method for 3½½-axis machining is comparatively competitive in performance and quality.

Globally optimal tool paths for sculptured surfaces with emphasis to machining error and cutting posture smoothness

“…To examine the applicability of relations presented in Equations 3 and 5 (chord error and scallop height estimation), a series of full factorial experimental designs were established and conducted by adopting four benchmark sculptured surfaces imposing different challenges when it comes to tool path planning. Figure 1a shows an open type bi-cubic Bezier surface (Gray, Bedi and Ismail 2003); Figure 1b shows a multivariable test surface (Manav, Bank and Lazoglu 2013); Figure 1c shows a complex-curvature surface (Roman et al 2015) and Figure 1d shows a challenging sculptured surface with two Bezier patches mirrored using a C0 continuous curve (Gray, Ismail and Bedi 2004). The surfaces depicted in Figure 1 are designated as SS-1; SS-2; SS-3 and SS-4 for easy reference in the paper.…”

Tool path generation for sculptured surfaces with 4-axis machining

“…Gray et al [6] combined the best features of principal axis method and multi-point method to develop a simple method to reduce time computation of tool positioning and avoiding gouge correction call rolling ball method (RBM). Roman et al [7] extended the application of the RBM to generate tool path planning and tool orientation strategies for 3+2-axis machining. These methodologies use local geometry data to determine the tool position and tool orientation along the path for each surface partitioning, reducing gouging possibilities.…”

Intelligent Dual Curve-Driven Tool Path Optimization and Virtual CMM Inspection for Sculptured Surface CNC Machining

“…Investigation for the usage of toroidal end-mills is mainly conducted for tool path planning in terms of tool positioning such that a curvature matching between the tool's geometry and the given sculptured surface exists in every cutter contact point. This assumption spans a noticeable number of research works for tool positioning, such as those presented in Roman et al, [13] dealing with the "rolling-ball" method applied to 3½½-axis machining, as well as in Warkentin et al, [14] where a number of discrete tool positioning methods for 5-axis surface tool paths are assessed using a toroidal cutter.…”