The tooth contact area is one of the important symbols to measure the meshing quality of bevel gears. Spiral bevel gear CNC machine tools have a large degree of freedom of processing and adjustment, which provides a broader development space for the design and manufacture of spiral bevel gears. Due to the many advantages of spiral bevel gear transmission, the demand for spiral bevel gears in the domestic market is increasing day by day, but there is still a large gap between China and foreign advanced level in gear processing technology. Taking Gleason’s contraction tooth hypoid gear as the research object, starting from improving tooth surface contact, improving production efficiency and studying the essence of four-axis NC machine tool processing technology, Based on the theory of differential geometry and gear meshing principle, the forming theory and method of spiral bevel gear are deeply studied by means of computer simulation. The main research results of this paper are as follows:
- When the hypoid gear pair is formed, the axis of the big wheel cutter head is perpendicular to the big wheel root cone, and the axis of the small wheel cutter head is perpendicular to the small wheel surface cone. In this way, the axes of the big wheel and the small wheel cutter head are parallel to each other, which can essentially avoid the phenomenon of diagonal contact in the theoretical contact area.
- When machining the small wheel, the spiral motion can be used to machine the tooth surface and the tooth root surface at the same time, so as to obtain the contracted teeth. The mismatch in the direction of tooth length is achieved by correcting the radius of the fine cutting cutter head of the small wheel; The denaturation coefficient is used to achieve the mismatch in the direction of tooth height.
- Based on the theory of generating wheel, the tooth cutting calculation model of spiral deformation semi generation method is established, and the adjustment parameters of the machine tool are given, which simplifies the complex adjustment and correction process of the previous forming methods to avoid diagonal contact in the theoretical contact area.
- Aiming at the domestic four axis CNC gear milling machine, the forming principle of processing Gleason spiral bevel gear with two knives is proposed, which realizes the rough and fine cutting of gear pair with two Cutterheads clamped twice, reduces the processing procedure and improves the production efficiency.
- The calculation method of machining convex surface of small wheel with double-sided cutter path method is derived, and the two tool digital machining model of spiral bevel gear is established. The two tool forming method can be flexibly and conveniently realized by using NC gear milling machine.
- Although the cutter head diameter is changed, the tooth length direction curvature that meets the design requirements can be achieved by changing the radial cutter position, and a better contact condition can be obtained.
In view of the extremely complex processing conditions of spiral bevel gears and the existing TCA verification methods have been very mature, the TCA method is used to verify the forming theory and method studied, which shows the feasibility of the forming theory.