| Spiral bevel gears are one of basic mechanical units that transmit motion between concurrent axes. Thanks to the great merits of the transmission, such as the big overlap ratio, the high loading capacity, the high transmitting efficiency, the stability, the small noises, and so on, they are widely used in automotive vehicle, planes, machine tools and all kinds of machines. However, the theoretical complexity causes that the machine tool structure and the machining adjustment are the most complex among all the stock-removing machines, and that the machining periodicity is very long. Therefore, it is of much importance to study machine tools of spiral bevel gears with high speed, high precision, high efficiency, much flexibility and high automation.The development of the computer and NC technology and the realization of the high precision electronic transmission enable machining gears with high precision, high efficiency, and much flexibility. Now, one after another, foreign gear plants adopt the advanced five-axes coordinated numerical controlling machining technique to machine spiral bevels in order to improve machining precision. Five-axes coordinated numerical controlling machining technique is applied widely in machining such complex parts as mould, laminae of turbine, screw propeller and avigation parts etc. Compared with traditional three-axes coordinated numerical controlling machining technique, five-axes coordinated numerical controlling machining technique increases two odditional freedoms so it can obtain higher machining efficiency and precision, especially in machining complex curved surfaces.Now national NC machines using in machining spiral bevel gears are mainly traditional machines and the NC machines depend on importation,not only the price being high,but being locked. Although there have been several domestic manufacturers producing NC macinges using in macining spiral beval gears, their NC system still mainly depends on introduction from foreign companies such as FANUC,Siemens and Philips, this universal CNC system is unable to make full of its functions, and CAD and CAM are independent. What's more, the price is also very high. If we only rely on importation, the higher price of tools and the blocked technology are very disadvantageous to the application of gear machines in our countries. So we should have our own CNC systems of spiral bevel gears. In view of our successfully-developing experience for many years, we put forward the thought of developing the CNC system for spiral bevel gears. My dissertation has drawn from the project - the Study of Copying & Digitizing Machining Technology which is sponsored by Natural Science Foundation of Henan province(Item number: 004053100).Centered around this subject, this paper mainly studies as follows:1. Briefly analyzes the five-axes coordinated numerical controlling machine tools, mainly including structure form, scheme variety, coordinate switching technique and cutter shaft controlling manner etc which is very important to the design of five-axes coordinated numerical controlling machining technology of spiral bevel gears.2. The engagement theory of spiral bevel gears is presented, mainly including the tangent plane, normal vector, curvature of spatial curved surfaces and relative curvature of conjugate surfaces, et al, according to the inputting of basic parameters, calculating the tooth flank of the spiral bevel gears, solving out the coordinates of tooth flanks, establishing the tooth flank models of spiral bevel gears.3. According to the result of flank of tooth calculating ,pre-proccess the spiral bevel gears and figure out the cutter location of spiral bevel gears NC maching4. Based on post-proccessing principle of five-axes coordinated numerical controlling machining and according to the established mathematical model of machine tools, deduces out post-processing algorithm of CNC machine tools for spiral bevel gears, program the post-proccessing tool for spiral bevel gears and uses the tool to pr... |
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