The manufacturing process for zero degree bevel gears is relatively complex. The main steps are as follows:
(1) Blank Preparation
Obtain blanks through forging or bar stock cutting.
Normalizing or annealing treatment to relieve internal stresses.
Rough turning of the outer diameter, end faces, and inner bore.
(2) Tooth Cutting
Zero degree bevel gears must be processed on specialized bevel gear cutting machines, the most famous of which are Gleason machines. There are two processing methods:
Generating Method
- Uses a cutter head with curved blades.
- The workpiece and the tool perform cutting according to a specific generating motion relationship.
- Suitable for batch production, offering high efficiency and accuracy.
Formate Method
- The larger gear is processed using the Formate method, where the tool shape exactly matches the tooth space.
- The smaller pinion is still processed using the Generating method to pair with it.
- Suitable for large module gears and small-batch production.
(3) Heat Treatment
Carburizing and quenching, or surface hardening.
Careful control of distortion is required; pre-deformation treatment may be applied when necessary.
(4) Finishing
Grinding: Uses CBN grinding wheels on specialized gear grinding machines to precision grind the tooth flanks, achieving accuracy up to DIN Grade 5.
Lapping: Paired gears are lapped together to improve the contact pattern and surface roughness.
Honing: Further improves surface quality and reduces noise.
(5) Inspection
Contact pattern inspection (using red lead powder or specialized testing machines).
Inspection of pitch deviation, tooth profile error, and tooth trace error.
Noise and vibration testing.