Design Of Polishing Machine For Curved Parts And Research Of Its Processing Mechanism

The automatic surface polishing for the curved parts, such as the taps, is one of the key issues to be solved in their actual production process. In order to overcome the shortcomings of manual polishing of poor processing efficiency, metallic dust pollution and human body injury accidents, and robot-assisted polishing shortcomings of expensive robot equipments and lower efficiency, this dissertation presents a polishing machine scheme of the combination by the nutation and planetary drive, and focuses on the mechanism design, kinematical analysis, polishing processing and analogue simulation. The main contents are as follows.On the basis of the analysis on the planetary spindle barrel type finishing machine, a processing method of combination by the nutation and planetary drive for curved surface parts is proposed and the mechanism is designed in this dissertation firstly.Then the kinematical equation is deduced based on the principle of coordinate transformation, the trajectory of a point on the surface of the tap is drawn by programming in Matlab software, and the influences of the nutation angle and gear ratio on trajectory and speed of the selected point are analyzed.A curved surface part is acted as the research object, the mesh model of the surface is obtained in gridding system, and the polishing speed and polishing angle of the sample discrete points on the surface would be calculated on the basis of mesh model and the kinematical equation which has been deduced. In this dissertation, the mean and the discrete coefficients of polishing speed and polishing angle of the points are acted as references of processing efficiency and uniformity, on which the influences of mechanism parameters such as the nutation angle and gear ratio are analyzed.Finally, a dynamic simulation model of the processing is built, and the dynamic simulation is finished with three-dimensional particle flow (PFC3D) discrete element software system. The influences of the nutation angle and gear ratio on processing efficiency were analyzed by considering the normal contact force and friction work on the part during processing process.