The timing belt is an endless belt with steel wire rope or glass fiber as a strong layer and covered with polyurethane or neoprene. The inner circumference of the belt is made into teeth to mesh with the toothed pulley. When the synchronous belt is driven, the transmission ratio is accurate, the force on the shaft is small, the structure is compact, the oil resistance is good, the wear resistance is good, and the anti-aging performance is good. The general use temperature is -20℃-80℃, v<50m/s, P<300kw, i<10, it can also be used for low-speed transmission for transmission requiring synchronization.

1.Overview

The synchronous belt transmission is composed of an endless belt with equidistant teeth on the inner peripheral surface and corresponding wheels. It combines the advantages of belt drive, chain drive and gear drive. When rotating, power is transmitted by meshing the belt teeth with the tooth grooves of the wheel. The polyurethane timing belt drive has an accurate transmission ratio, no slip, and a constant speed ratio can be obtained. The transmission is stable, vibration absorption, low noise, and a large transmission ratio range, generally up to 1:10. The allowable linear speed can reach 50M/S, and the transmission power can range from a few watts to a hundred kilowatts. High transmission efficiency, generally up to 98%, compact structure, suitable for multi-axis transmission, no lubrication, no pollution, so it can work normally in places where pollution is not allowed and the working environment is harsh. Transmission products are widely used in various types of mechanical transmission in various industries such as textiles, machine tools, tobacco, communication cables, light industry, chemical industry, metallurgy, instrumentation, food, mining, petroleum, and automobiles.

2. Features of timing belt

(1) Accurate transmission, no sliding during work, and constant transmission ratio;

(2) Smooth transmission, buffering and vibration reduction capabilities, and low noise;

(3) The transmission efficiency is high, up to 0.98, and the energy saving effect is obvious;

(4) Convenient maintenance, no need for lubrication, and low maintenance cost;

(5) The speed ratio range is large, generally up to 10, and the linear speed can reach 50m/s, with a large power transmission range, up to several watts to hundreds of kilowatts;

(6) It can be used for long-distance transmission, and the center distance can reach more than 10m.

3. The main failure modes of synchronous belt transmission

①Fatigue fracture of belt body;

② Shear and crush with teeth;

③The belt side, belt teeth are worn, and the wrapping cloth peels off;

④ The load-bearing layer is elongated, the pitch is increased, the interference of the teeth is formed, and the teeth are climbing;

⑤The belt body is broken by impact and overload.

4. Timing belt classification

Synchronous belt teeth have trapezoidal teeth and arc teeth. There are three types of arc teeth: arc teeth (H series also known as HTD belts), flat top arc teeth (S series also known as STPD belts) and concave top parabolic teeth (R series).

Trapezoidal tooth synchronous belt

Trapezoidal toothed synchronous belts are divided into single-sided toothed and double-sided toothed belts, referred to as single-sided belt and double-sided belt for short. Double-sided belts are divided into symmetrical tooth type (code DA) and staggered tooth type (code DB) according to the arrangement of the teeth. Trapezoidal tooth synchronous has two size systems: pitch system and modular system. my country adopts pitch system , And according to ISO 5296, the corresponding standards GB/T 11361-11362-1989 and GB/T 11616-1989 have been formulated for synchronous belt transmission.

Spiral synchronous belt

The spiral toothed synchronous belt has the same structure as the trapezoidal tooth synchronous belt except that the tooth profile is curved. The belt pitch is equivalent, and its tooth height, tooth root thickness and tooth root fillet radius are larger than trapezoidal teeth. After the belt tooth is loaded, the stress distribution is better, the stress concentration at the root of the tooth is smoothed, and the bearing capacity of the tooth is improved. Therefore, the spiral tooth synchronous belt transmits more power than the trapezoidal tooth synchronous belt, and can prevent the interference of the teeth during the meshing process. The spiral toothed synchronous belt has good wear resistance, low noise during operation, no lubrication, and can be used in harsh environments with dust. It has been widely used in food, automobile, textile, pharmaceutical, printing, papermaking and other industries.

5. Working principle of synchronous belt:

The synchronous belt drive is composed of an endless belt with equidistant teeth on the inner peripheral surface and a pulley with corresponding teeth. During operation, the belt teeth mesh with the tooth grooves of the pulley to transmit motion and power. It is a comprehensive belt A new type of belt transmission with the advantages of transmission and chain transmission and gear transmission. Precautions for the installation and use of timing belts and timing wheels: Reduce the center distance of the pulleys. If there is a tension pulley, loosen it first, and then adjust the center distance after installing the belt. For transmission with a fixed center distance, remove the pulley first, install the belt on the pulley, and then install the pulley on the shaft to fix it.

You should also pay attention to the following points during installation:

①When installing the timing belt, if the center distance of the two pulleys can be moved, the center distance of the pulleys must be shortened first, and then the center distance is reset after the timing belt is installed. If there is a tension wheel, first relax the tension wheel, then install the timing belt, and then install the tension wheel.　　

②When installing the timing belt on the pulley, remember not to use too much force or use a screwdriver to pry the timing belt hard to prevent the tensile layer in the timing belt from breaking unnoticeably. When designing the pulley, it is best to choose a structure that allows the two shafts to move closer to each other. If the structure does not allow it, it is best to install the timing belt and the pulley on the corresponding shaft.

③Control proper initial tension.

④ In the synchronous belt drive, the parallelism of the axis of the two pulleys is required to be relatively high, otherwise the synchronous belt will deviate when working, or even jump out of the pulley. The non-parallel axis will cause uneven pressure, which is the early wear of the belt teeth.

⑤The frame supporting the pulley must have sufficient rigidity, otherwise the two axes will not be parallel when the pulley is operating in the code lock.