Study On Milling Method Of Hypoid Gears

Hypoid gears have many advantages such as high coincidence degree, high strength,high reliability and so on.So they are widely used in aircraft, ships, machine tools, heavymachinery and other products. Hypoid gears tooth surfaces so complicated that the cuttingprocess is complex. The existing methods of cutting gears need repeated trial cuts andadjustments which makes the process a long period. At the same time, it is difficult to ensurethe interchangeability of the hypoid gears. The gears which are processed with the traditionalmethods have some problems in their transmission, such as incomplete contact, smallintensity or imperfect stability. Based on the development of the hypoid gears, this paperpresents the generating-line method which designs the cutting tools by the contacted line ofthe tooth surfaces and provides gear cutting movement through the formation of the matingsurface. In other words, the cutting edge is manufactured by the tooth surface line and thegears are cut on the special designed machines. In this paper, a three-axis machine is used forthe hypoid gears cutting which includes one translational axis and two related rotation axis.Using the generating-line method to cut hypoid gears has many advantages. Firstly there isno principle error, secondly the machine and cutting tools are simple than others, thirdly thismethod can reduce processing costs. The main research contents of this paper are as follows:1. The development of the hypoid gear completely and the traditional cutting methods ofthe hypoid gear are summarized. All of these have proved the importance of cutting hypoidgears using generating-line method.2. The basic principle of generating-line method is researched deeply and the generatingprinciple of the hypoid gear surfaces is analyzed. This paper has proposed a method ofensuring the small gear·s base cone through the large one. After the base cone and base planeare ensured, the paper has analyzed the cutting area and made curve fitting so that thedeductions of the processing equations will be easy. The equations of the processingequations for the large and small gears are deducted.3. In order to make the simulations of the gear cutting, a three axis machine model is established through the VERICUT. The machine is set up based on the cutting process,including A axis used for the rotation of gear blanks, C axis used for revolution and Y axisused for the movement of the generating-line cutting edge. Generate the gear blanks and toolmagazine by the sweep method in VERICUT. The NC programs for the gears are written andthe simulations in the system of sin840d are made.4. The large gear blank is processed and the process of the large gear is finished on thespiral bevel gear machine. In the end, prove the generating-line method by checking the gearsurfaces. The gear produced by the method is perfect and the gear machine has a stabilityduring its cutting process.