Gear hobbing features:
1. high productivity.
2. The tooth profile accuracy of hobbing is lower than that of gear shaper, and the number of tangents forming the tooth profile envelope is only related to the number of flutes of hob and the number of heads of basic worm, which cannot be increased or decreased by changing the processing conditions.
3. Machining worm gear can only use hobbing.
Gear shaping features:
1. When cutting gears with large modulus, the gear shaper speed is restricted by the reciprocating inertia of the gear shaper cutter spindle and the rigidity of the machine tool. The cutting process has lost idle time, so the productivity is not as high as that of hobbing. The productivity of gear shaper is higher than that of gear hobbing only when the gears with small modulus, many teeth and narrow tooth width are processed.
2. The number of tangents forming the tooth envelope is determined by the circumferential feed and can be selected. During gear shaping, the cutting of the gear shaper cutter along the tooth direction is continuous, and the roughness of the tooth surface is fine during gear shaping.
3. Tooth orientation error during gear shaping is mainly determined by parallelism error between rotary axis of main shaft of gear shaper and rotary axis of worktable. Because of the high frequency of reciprocating motion when the gear shaper cutter works, the wear between the main shaft and the sleeve is large, so the tooth direction error of the gear shaper is relatively large.
4. Only gear shapers can be used for machining gears with shoulders and double or multiple gears with narrow empty cutter slots.
Characteristics of shaving:
1. The shaving precision is generally 6 ~ 7 grades, and the surface roughness Ra is 0.8 ~ 0.4μ m, which is used for the fine machining of unquenched gears.
2. The productivity of gear shaving is high, and it generally takes only 2 ~ 4 minutes to process a medium-sized gear, which can increase the productivity by more than 10 times compared with gear grinding.
3. Because gear shaving is free meshing and the machine tool has no generating motion transmission chain, the machine tool has simple structure and easy adjustment.
