What are the classification and advantages and disadvantages of precision gears

Jun 23, 2022

Precision gears are toothed mechanical parts that can mesh with each other, and are widely used in mechanical transmission and the entire machinery. There are many kinds of gears, and the classification method is usually based on the linearity of the gear shaft. Generally divided into three types: parallel axis, intersecting axis and staggered axis. Parallel shaft gears include spur gears, helical gears, internal gears, racks and helical racks.

What are the classification and advantages and disadvantages of precision gears(图1)

Gears with parallel shafts:

1. Spur gears: cylindrical gears parallel to the axis. Because it is easy to process, it is widely used in power transmission. There are two main types of spur gears: external and internal. The external gear has teeth cut on the outer surface of the cylinder. The two external gears mesh together and rotate in opposite directions. In contrast, internal gears have teeth cut on the inner surface of the cylinder.

2. Rack:A linear rack that meshes with a spur gear. When the pitch diameter of the spur gear becomes infinite, it can be regarded as a special case. Racks can be milled or ground according to customer requirements and can be made of different materials and hardened differently. According to different bearing conditions, customers can choose tooth surface material quenching and tempering, induction quenching and laser quenching and other processes.

3. Internal gear: When meshing with the spur gear, the toothed gear is processed inside the ring gear.

4. Helical gears: cylindrical gears with helical tooth lines. It is widely used because it has higher strength and smoother operation than spur gears. Axial thrust is generated during transmission. The helical gear has low running noise, light structure design and economical price.

5. Rack gear meshed with helical rack and helical gear: The contact line of the helical gear teeth is a straight line inclined to the gear axis. During the meshing process of the two tooth profiles, due to the limitation of the tooth height, the length of the contact line gradually increases from zero, so that the transmission is smooth and the noise is low. At the same time, this meshing form also reduces the influence of manufacturing errors on the transmission.

6. Herringbone gear: The tooth line is a gear formed by the combination of left and right helical gears. Some do not generate thrust in the axial direction; the herringbone gear has high coincidence, small axial load, high bearing capacity and stable operation.