Arc-intersect method for [formula omitted]-axis tool paths on a 5-axis machine

Abstract

An inherent problem with simultaneous 5-axis machining is that it often suffers from dramatic reductions in feed rate when the tool axis is in the vicinity of the singularity point of the machine; during large orientation changes over small distances; during rotary axes reversals and from interpolation of the tool axis vector. 3 1 2 1 2 -axis machining offers an alternative strategy that can be used to overcome these problems and still maintain some of the salient features of 5-axis machining to improve machining times over 3-axis ballnose machining. In 3 1 2 1 2 -axis machining, during cutting the machine moves only its three linear axes while the two rotary axes are locked, resulting in a fixed tool orientation. Locking the rotary axes generates fewer fluctuations in the feed rate than simultaneous 5-axis machining and results in a more consistent surface finish with lower variations in cutting force and torque. A new tool positioning strategy called the Arc-Intersect Method (AIM), which can also be applied to simultaneous 5-axis machining, is presented here for 3 1 2 1 2 -axis machining on simultaneous 5-axis machines using toroidal or flat endmills. A cutting test was performed and the part was measured with a CMM to check for accuracy and to measure the cusp heights. Machining times were compared to 5- and 3-axis tool paths and cutting torque measurements were compared between 3 1 2 1 2 - and 5-axis machining.