| Non-circular gear is a kind of special gear,and it has the advantages of cylindrical gear and cam mechanism.In the process of meshing,the instantaneous angular velocity ratio of non-circular gear transmission is constantly changing,which can realize complex and special variable transmission ratio motion and function operation.However,it is difficult to design and manufacture the non-circular gear,which greatly limits the development of the non-circular gear.With the rapidly development of NC technology and CAD/CAM technology,it has given a new way of processing non-circular gears.As we can see,CNC shaping is a general and universal non-circular gear processing method,but now,many problems in processing have not been solved effectively.Because of these,shaping technical problems of non-circular gears are studied in this dissertation,and the main research contents are as follows:1?A 3-axis linkage model of non-circular gear shaping based on the model of the envelope is obtained by using the method of vector form of pitch curve.According to the principle of shaping and tooth profile forming of non-circular gear,and closely combined with the structure of three axis CNC gear shaping machine and the shaping process,a 3-axis linkage model of non-circular gear shaping based on the model of the envelope is obtained by using the method of vector form of pitch curve.It lays a solid theoretical foundation for the shaping of non-circular gears in the general 3-axis CNC gear shaping machine.2? Presetting cutter method and Cutter retracting technology are put forward.To determine the starting position of non-circular gear tooth processing,combined with the structure of three axis CNC gear shaping machine,some datum planes for presetting cutter are designed in the structure of gear blanks,fixture tools and gear shaper cutters,and the relevant methods of presetting cutter are put forward.At the same time,through gear shaper cutter carrying out the cutter retracting interpolation motion when the cutter approaches the bottom dead center,a cutter retracting mathematical model has been established to avoid interference.Finally,the correctness of the presetting cutter method and cutter retracting model has been proved by processing example.3? A complete method of shaping process of non-circular gear is set up.Through designing and ensuring the parameters of non-circular gear pitch curve,gear blanks,fixture tools,and the shaping factors such as feed rate,cycle times and interpolation algorithm,a complete method of shaping process of non-circular gear in general 3-axis CNC gear shaping machine is set up.It provides a feasible method and way for shaping non-circular gears.4? The automatic programming system for shaping non-circular gears is developed.Based on the MATLAB and Visual C++ software,an automatic programming system is developed.This system not only can realize the shaping process simulation of non-circular gear,but also get the gear shaping codes.Finally,with a pair of 3-order sinusoidal gear ratio non-circular gears,the correctness and completeness of shaping technical and the automatic programming system has been proved. |
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