Study On The Key Technology Of CNC Internal Gear Form Grinding Machine

The planetary gearing which is composed by sun gear, planet gear and internal gear is widely used in mechanical transmissions. In order to improve the manufacturing accuracy of the planetary train and increase its loading capacity, the key is to solve how to realize the high efficient grinding of internal gear with hard face. At present, the finishing of involute internal gear is an urgent difficulty to be solved in our country. It is necessary to develop CNC internal gear form grinding machine. The key problems in developing internal gear form grinding machine are to realize "on-line" dressing of forming grinding wheel and to design the grinding wheel support. The researches on how to design the grinding wheel support and how to realize the "on-line" dressing of forming grinding wheel are performed in this paper.Based on gear forming grinding principle, the grinding wheel support is designed. And the grinding plan named "setover" is proposed, by which the problem that the minimum internal diameter of internal gear is limited by the size of wheel head can be solved, thus enlarging the machining range of grinding machine. Based on involute forming principle and established parameter equations, the dressing of grinding wheel with involute profile is studied by means of generation method and interpolation method. Mathematical model of wheel dressing is established, and the wheel dressing device is designed. Based on established mathematical model of involute profile, taking the spread angle as variable and the nomal error allowance as optimization index, the interpolation of involute is completed in two coordinates. The CNC dressing software of forming wheel with involute profile is prepared based on VC++6.0, thus realizing the unity of PC automatic programming and NC machining, and improving the flexibility of machine tool. The jumping division calculation program is prepared on the basis of analyzing the tooth indexing accuracy mathematically. Jumping division grinding is helpful to improve the machining accuracy of machine tool. The grinding wheel dressing experiment and gear grinding test are completed successfully on the developed internal gear grinding machine.Gear grinding tests show that the developed CNC internal gear grinding machine has high machining accuracy and flexibility. The successful development of this machine will be helpful to change current internal gear finishing process, and change the situation that the internal gear grinding machine is imported from foreign countries. thus promoting the development of gear manufacturing industry in our country.