Modeling And Parametric Design Of Hob Applied To VGMC

Hobs are the most used gear cutting tools in gear machining. The precision of the hob is an important factor of restricting the quality of gear. At present, ISO has not establish the traceability system for hob measurement. There is hardly the high-precision testing model which used for hob measuring instrument. It is difficult to trace the source for hob measuring. The correctness of the measurement program also cannot be judged by the result of measurement. Therefore, a precise model of hob has been established in this paper. By measuring the model in the virtual gear measuring center, the cost of development about measurement program will be reduce, and the efficiency will be improve. The main research results and innovation as follows:First, the equation of the cutting edge, shoveling curve and equal diameter line on rake face are established according to the principle of hob molding process. The mathematical model of Archimedes gear hob tooth surface is obtained.Second, the shoveling curve and equal diameter line on rake face are dispersed according to the mathematical model of gear hob. A series of theory discrete points on tooth surface are obtained. A artificial STL model of hob is constructed. As a digital basis, this model applied to verify the measurement program in virtual gear measuring center. The shoveling surface and the rake face are constructed based on the cutting edge. In this way, the uniqueness of the data on the intersection is ensured, and the gaps or overlaps of the STL model are avoided.Third, the shoveling surface is built based on the accurate shoveling curves, and the accuracy of the shoveling surface is ensured in this way. By using C++and Pro/Toolkit, the parametrical design system which based on Pro/E is set up. The main features of the system are reading parameters, updating model, displaying parameters and so on. The STL model in this paper satisfies the requirement of virtual measuring center. The models built by parametrical design system can be used for visual presentation in the virtual gear measuring center.