Influence of position-dependent geometric errors of rotary axes on a machining test of cone frustum by five-axis machine tools

A machining test of cone frustum described in NAS (National Aerospace Standard) 979 is widely accepted by machine tool builders to evaluate the machining performance of five axis machine tools This paper discusses the influence of various error motions of rotary axis on a five-axis machine tool on the machining geometric accuracy of cone frustum machined by this test Position-independent geometric errors or location errors associated with rotary axis such as the squaieness error of a rotary axis and a linear axis can be seen as the most fundamental errors in five axis kinematics More complex errors such as the deformation caused by the gravity the pure radial error motion of a rotary axis the angular positioning error of a rotary axis can be modeled as position-dependent geometric errors of a rotary axis This paper first describes a kinematic model of a five-axis machine tool under position-independent and position-dependent geometric errors associated with rotary axis The influence of each error on machining geometric accuracy of a cone frustum is simulated by using this model From these simulations we show that some critical errors associated with a rotary axis impose no or negligibly small effect on the machining error An experimental case study is presented to demonstrate the application of R test to measure the enlargement of a periodic radial error motion of C axis with B-axis rotation which is shown by present numerical simulations to be among potentially critical error factors for cone frustum machining test (C) 2010 Elsevier Inc All rights reserved