Research On Geometric Error Measurement And Compensation Technology Of Rotary Axis

With the wide application of precision machining technology,the error and accuracy of the rotary axis of CNC machine tools have received increasing attention.The error compensation method directly superimposes the compensation value on the motion axis of the CNC machine tool,thereby eliminating or reducing the machine tool error value,which is a common method for improving the accuracy of the machine tool.In this paper,the rotating axis of CNC machine tool is taken as the research object,and the geometric error measurement and compensation research is carried out.The main research contents of this thesis are as follows:(1)Mechanism analysis of machine tool rotation axis error formation.Analyze the error source of the rotary axis,summarize the geometric error elements of the rotary axis of the machine tool and represent them with symbols.According to the multi-body system kinematics method,the description of the machine tool topology and the expression of the homogeneous coordinate transformation matrix on the pose relationship between adjacent bodies are analyzed.Influence of machine tool rotation axis error on tool position and attitude deviation during machine tool movement.(2)Research on geometric error measurement technology of machine tool rotary axis.Using the angular pendulum tester to measure the rotational angle positioning error of the rotating shaft,according to the measuring principle of the ball bar instrument,the remaining geometric errors of the C-axis are identified for the C-axis of the horizontal turntable,combined with the radial,axial and tapered mounting modes of the ball bar.And the rod length value is eliminated by the least squares fit to eliminate the ball bar installation error.For the swing axis B axis,combined with the three different swing length measurement modes of the swing axis and the method of the ball joint installed along the three axial directions,the remaining geometric errors of the B axis are identified.(3)Research on geometric error compensation technology of machine tool rotary axis.Through the inverse kinematics calculation and analysis of the machine tool axis,the compensation method of the rotating axis error is studied.Aiming at the discontinuity of the geometric error measurement of the rotating axis,a polynomial fitting prediction method for selecting the optimal order is studied.Finally,the geometric error compensation module of the rotary axis of HNC-8 system and its compensation principle are analyzed.The meaning of the parameter setting value in the compensation parameter is explained in detail.(4)Rotary axis geometric error measurement and compensation application verification.Taking the rotating axis of the DXJ320-5A five-axis machine tool as the research object,the geometric errors of the C-axis and the B-axis were measured using the angular pendulum tester and the ball bar.The HNC-8 system rotary axis geometric error compensation module is used to compensate the rotational axis angular positioning error,and the B-axis and C-axis positioning accuracy are increased from the angular second to the angular second,respectively.The B-axis position deviation was compensated by the HNC-8 system rotary axis geometric error compensation module.The compensation was verified in the horizontal radial and conical installation modes of the ball bar,and the compensation effect reached more than 75%.