Research On Geometric Error Identification And Compensation Of Five-axis NC Machine Tool With Rotary Axes

With the higher requirements of multi-axis NC machine tools, exposed machine tool errors have become an obstacle on its further development. Error compensation method can reduce the manufacturing cost of high-end equipment to a certain extent which has obvious economic benefits. This paper’s mian work is as follows:1) Analysis the motion transmission of machine tool and develop its topological structure. Use rigid kinematics and homogeneous coordinate transformation matrix variation to describe the change rule of coordinate values. At last, develop an error model for machine geometric errors based on multi-body system theory in the cutting point and check its correctness.2) Propose A, C-axis error measurement methods based on the existing error identification methods, derive geometric error identification models. Increase measurements to replace the use of Laser interferometer which making the identification process efficiency. Consider the installation errors of tool cup, center-biased errors of ball, aligning and other preparatory works, then, implement A, C-axis measurement programs and plug experimental data in the identification model, get 6 items of A, C-axis geometric error parameters.3) Analysis machine tools A, C axis motion features, establish the tip’s position vector and direction vector equation on work-piece coordinate system. Divide error decoupling compensation into two steps: compensate the direction vector firstly, and then compensate the position vector. Take A, C-axis measurement programs’ compensation as example, it contains a detailed analysis of the A, C axis geometry displacement and rotation error compensation process which verifies the feasibility of error compensation model.