Verifying the accuracy of five-axis machine tool focused on kinematic ISO tests using a torus-shaped test work piece

摘要

In the aerospace industry the application of five-axis machines is increasing and becoming common practice. The determination of the accuracy of such five-axis machine however is often difficult because linear and rotary axes are used combined resulting in complex motions. Typical five-axis tests are specified in ISO10791-6 (e.g. AK4, BK4, CK4) and a modified BK4 test is used in this paper to determine the machine's accuracy first employing five machine axes simultaneously. A new test work piece is derived that can be milled while imitating the same machine movements of the respective BK4 test. For this a torus-shape is cut in the top edge of a cylindrical work piece with a spherical radius mill enabling five-axis movements while cutting. After milling this test work piece the accuracy of the torus shape is measured using a CMM to verify the machine's accuracy in five-axis mode. Finally the machine deviations measured during the BK4 measurement are compared with the CMM results revealing the same amplitude. A Q-value is introduced and proposed in this paper to express this amplitude of machine deviations as a single value parameter, indicating the machine's accuracy when using five axes.