Research On Precision Machining And CNC Machine Tool Specialzing Of Globoid Indexing Cam

The globoid indexing cam is an indexing mechanism with high speed and high accuracy for driving perpendicular axes in space,which was firstly designed by an American,C.N.Neklutin,in 1920s.Because the profile of the working curve of the cam is in high accuracy and great complexity,it is very difficult for producing.Many developed countries,such as America,Russia and Switzerland have made great development.The main method is forming-method.On the other hand,the research of globoid indexing cam in China began about 1970s and mainly focused on the simple globoid indexing cam.The CNC devices with two rotary coordinates and special spatial location are needed to produce the high accuracy globoid indexing cam.At present,in our country,high accuracy CNC machine tools for producing the roller gear indexing cam generally have disadvantages.And they need to be developed and improved.So,it is necessary to re-develop and manufacture the new CNC machine tool specializing in machining the globoid indexing Carn.In this paper,analysis and compare of the manufacturing methods was made based on the information at home and abroad.Found the precision finishing method of the high accuracy globoid indexing cam is the combination of forming-method and double envelop.Finishing cutter paths for surface are generated from high-speed milling and side milling cut.This paper presented the manufacturing process of the globoid indexing cam.Combing machining center those paths are transformed to post files.Virtual machining center is used to simulate process of cutting to avoid gouge and collisions.Which provide theoretical basis for machining parts and save much time and raise working efficiency.Second,a relation model between cutting forces and cutting speed is established for high speed milling condition on the basis of research into the theory of shear distortion and the discrete milling cutter.And the formula for angle of shear plane is modified by chip shortening coeffieient.It's the academic support for structural design and the model selection of electrical motor.By analyzing the working principle,technics and process of the manufacturing of the globoid indexing cam,modular design thought,the author put forward both vertical and horizontal feasible projects,for the manufacturing of the globoid indexing cam.By comparison and analysis,final scheme is figured out,which is characterized as horizontal structure,5-axis control,NC indexing unit for rotating feed of workpiece,NC rotating table for feeding of cutter,and electrical spindle.The milling machine belongs to special CNC milling machine tool.