Abstract: The problem of machining error online monitoring and compensation method is studied, and the machining error online monitoring and compensation method is proposed which takes numerical control forming gear grinding machine as the research object. The relative position of work piece and tool is important for machining precision during machining process. One can get the relative position by testing the built-in signal which include encoder and direct encoder signal. In the proposed method, the space trace of machining is calculated from the built-in signal which is processed by the homogeneous coordinate transformation. The main factors that bring out the machining error can be determined by analyzing the processed built-in signal, and compensated into the numerical control system by online real time method. The proposed method is implemented on a numerical control forming gear grinding machine to improve its precision. Compared with the coordinate measuring machine test result, the proposed method can detect the form of the machining error. After compensating, the tooth alignment machining error is lowered obviously.

Key words: Error compensation, Homogeneous coordinate transformation, Machining process monitoring, Precision test