Research On Error Compensation Method In Aspherical Machining Process

The two questions constraining the optical aspheric components widely using are machining precision and machining efficiency. The tangent method aspheric shaping principle proposed by aspheric laboratory in Changchun University of Science and Technology can solve the two questions effectively. Due to the widespread static and dynamic error in the process of the CNC machine, the actuator will produce tiny deviation in the execution processing that will affect the machining accuracy. So it’s an imminent to put forward a kind of effective method of compensation for the tangent method CNC shaping aspheric machine which can compensate the errors in processing and improve the machining accuracy.The paper describes the basic processing principle of the tangent method CNC shaping aspheric machine, that makes the tool to locate under the controlling of the PMAC controller, makes the tool move along the tangential direction of each processing point achieving the speed interpolation of each axis. Then the structure of the tangent method CNC shaping aspheric machine has been showed. The relevant content of the multi-body system theory has been described which is the theoretical basis for the paper to study the motion errors of the tangent method CNC shaping aspheric machine. We analysis the features of translation and rotation and the matrix transformation principle based on the multi-body system movement. The ideal and actual motion equations in the multi-body system has been deduced. The analysis theory of the motion errors in general applicable objects has been established. We analysis the structural properties of common CNC machines, get the common method of modeling for the CNC machine errors, study the modeling steps of the tangent method CNC shaping aspheric machine, get the geometric topology for the machine. We deduce the posture condition equations for the machine precision machining under actual condition. The39geometry errors of the tangent method CNC shaping aspheric machine has been analyzed in detail. The spatial mathematical error model of the tangent method CNC shaping aspheric machine has been deduced. We introduce the Renishaw ML10laser interferometer and its using methods and interface. We develop a error compensation software based on VC6.0independently. Finally we take an experiment for a k=-0.25, c=0.005, D=60mm aspheric curve. The experiment result shows that the compensation model can compensate the geometric errors of the tangent method CNC shaping aspheric machine effectively. We have made contributions to improve the machining precision of the tangent method CNC shaping aspheric machine.