Influence of Component Errors of Rotary Axes on a Machining Test of Cone Frustum by Five-axis Machine Tools
Cefu Hong, Soichi Ibaraki, Atsushi Matsubara
Abstract
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 causes associated with rotary axes on a five-axis machine tool on the machining geometric accuracy of the cone frustum machined by this test. Location errors, or kinematic errors, associated with rotary axes, such as the squareness error of a rotary axis and a linear axis, can be seen as the most fundamental errors in five-axis kinematics. Other more complex errors, such as the deformation caused by the gravity, the run-out of a rotary axis, the angular positioning error of a rotary axis, can be modeled as component errors of a rotary axis. This paper shows that some error factors, such as run-out and angular motion of C-axis, impose sufficiently small effect on circularity error on the cone frustum machining test. It also clarifies that a center shift of a C-axis caused by the B-axis rotation can be a potentially critical error factor for cone frustum machining test.
Key Word: five-axis machine tool, machining test, cone frustum, location error, component error
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