| Gear is an important transmission element in mechanical manufacturing, it hasthe features of constant power output, heavy loadings, high transmission efficiency,long operating life, stable transmission ratio, and compact structure, etc. Due to itsimportant role in mechanical transmission and the complexity of its form, the designand manufacturing level of gears has become one of the symbol of modern industrylevel of a country, and become the research hotspot in academe too. Thus, it is ofgreat theoretic and realistic significance to research on correlative technology ofgears. In order to improve the machining precision, the cause occurred in the gearmachining process must be studied. Traditional gear machine tools are notnumerically controlled, and the gear is machined through a series of change gears andlong drive chain. Gear accuracy is related to the manufacturing accuracy of eachsegment of gear machine tools. In recent years, with the development of CNCtechnology of gear machine tools, the drive chains of traditional gear machine toolsare shortened greatly, which offered the technology base for improving gearmachining precision. Based on the research status and existent problems of gearmachining error, taking CNC gear shaper as research object, some issues are studiedin this paper. 1 Kinematics modeling of CNC gear shaper is built based on multi-body systemtheory. According to the specific movement of CNC gear shaper, movementreference coordinate system and the corresponding error vectors and errortransformation matrixes are set up, and the geometric method for demonstrating themovement errors of CNC gear shaper. Based on the demonstrating method (In realproject object, the real movement track deviates from the ideal track due to theexistence of manufacturing and installation error of each part, from which, the idealmovement is not accomplished.), general kinematics equation of CNC gear shaper isderived under the condition of error. 2 From the point of view of processing system, gear machining precision isinfluenced by many factors, analysis modeling of gear error and drive chain error arebuilt by integrating kinematics theory of multi-body system with theory of gearengagement. Based on this model, sensitive error factors of gear processing is putforward in this paper, thus, the accurate tooth surface equation is gained, and thesimulation of tooth profile and tooth surface is carried out. According to theclassification and test criterion of gear machining error, tooth profile error, circularpitch error and accumulated pitch error of gear are derived selectively, which realizethe quantitative calculation of machining error of gear. 3 The measurement and compensation of principal axis rotating error of CNCgear shaper and the process experiment of gear has been done on CNC gear shaperYK5120. In this experiment, double frequency laser interference equipment ML 10,Renishaw/RX10 rotary table and other optical units are used. Gear machining testshave been done under the condition of compensation and uncompensation. Theexperiment result indicates that some test items, such as tooth profile error, circularpitch error and accumulated pitch error of gear are improved by one grade.
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