Sprocket chain selection strategy

1. What is chain drive

The chain drive consists of two sprockets and a chain, an intermediate flexible part wound around the two wheels. Relying on the meshing between the chain and the sprocket to transmit the motion and power between the two parallel shafts, it belongs to the forced transmission with meshing properties. Among them, roller chain drives are widely used.

The chain drive is composed of the main and driven sprockets mounted on parallel shafts and the annular chain around the sprocket, as shown in the figure below, with the chain as the intermediate flexible part, and the movement and power are transmitted by the meshing of the chain and the sprocket teeth.

2. Roller chain structure

It is composed of an inner plate, an outer plate, a pin, a sleeve and a roller. When the chain drive is working, the rollers on the sleeve roll along the sprocket tooth profile, which can reduce the wear of the chain and sprocket teeth.

3. Chain joint form

When the number of chain links is an even number, the connecting chain link is adopted, and its shape is the same as the chain link, and the pin shaft is fixed with the connecting chain plate with a locking member such as a cotter pin or a circlip at the joint; When the number of links is odd, a transition link must be added. The chain plate of the transition link is subject to additional bending moments during operation, so the use of odd-numbered links should be avoided as much as possible.

4. the difference between sprockets and gears

(1)The gear is involute toothed, and the sprocket is "three arc straight line" tooth shape;

(2)The gear is transmitted by meshing the teeth of the two gears, and the two sprockets are transmitted through the chain;

(3)The gear has more torque than the sprocket, and the sprocket transmission is suitable for the transmission with a large center distance, which has the characteristics of light weight and low cost;

(4)The gear can be transmitted between parallel shafts and staggered shafts, while the sprocket can only be transmitted between parallel shafts.

5. the selection of sprocket shaft spacing

The shortest shaft spacing is that the two sprockets do not touch each other, but please choose a small sprocket winding angle of 120° or more.

Generally speaking, the ideal shaft spacing is 30~50 times the chain pitch used, and when the pulsating load is acted, please choose less than 20 times.

6. the characteristics of chain drive compared with gear drive and belt drive

(1) Multi-tooth bearing, safe and reliable

(2) Flexible transmission, absorbing shock and vibration

(3) The center distance range is large, and the manufacturing and installation accuracy requirements are low

(4)Compared with belt drive, the transmission ratio is accurate and the transmission efficiency is high, which is suitable for the harsh environment of high temperature, dust and humidity