Gear Machining Methods and Guidelines
Gear Grinding: IT6 to IT4 → IT3, Ra: 0.8 to 0.2 μm. Principle: Forming method and generation method.
(1) Forming Method Gear Grinding IT6 to IT5, Ra: 0.8 to 0.4 μm, using a forming grinding wheel for grinding, the productivity of the gear transmission is high, but the machining accuracy is low, and it is less commonly used.
(2) Generation Method Gear Grinding
Cone Grinding Wheel Gear Grinding: The grinding wheel's cross-sectional tooth profile is that of an imaginary rack tooth profile. The workpiece rolls to the right, and the right side of the grinding wheel grinds the right side of one tooth space from the root to the top; then the workpiece rolls to the left, and the left side of the grinding wheel grinds the left side of the first tooth space, also from the root to the top. When both sides of the first tooth space are completely ground, the grinding wheel automatically disengages from the workpiece, which then makes an indexing rotation, and then rolls to the right to grind the second tooth space, repeating this cycle until all teeth are ground.
Gear Lapping:
IT7 to IT6, Ra: 1.6 to 0.2 μm. Equipment: Gear lapping machine. Lapping agent: Abrasive particles: 220# to 240#, active lubricating oil. Features: Similar to honing, it can only reduce surface roughness and cannot improve tooth profile accuracy.
Parallel Axis Lapping Method:
Process: The lapping wheel's axis is parallel to the axis of the gear being lapped. During lapping, the gear drives the lapping wheel to make a backlash-free free meshing movement, and the gear also makes an axial reciprocating motion, with the lapping wheel being slightly braked. After a period of time, the lapping wheel and the gear being lapped rotate in opposite directions, ensuring that both sides of the teeth are evenly lapped.
Features: Due to the uneven sliding speed on the tooth surface, the lapping amount is also uneven, with a higher sliding speed and greater lapping amount at the top and root of the teeth.
Gear Transmission with a Moving Axis
There are many types of planetary gear transmissions, and the performance of different types varies greatly. It is very important to choose the type reasonably according to the working conditions. Commonly used types include the ordinary planetary transmission composed of a sun gear, planetary gears, an inner gear, and a planetary carrier, epicyclic gear transmission with a small tooth difference, cycloidal pin gear transmission, and harmonic drive, etc. Planetary gear transmissions are generally composed of parallel-axis gears and are characterized by small size and light weight, with the input and output shafts being on the same straight line. Their application is becoming more and more widespread.
