What types of transmission belts are commonly used? Describe their respective characteristics and applications.

Flat belt is the oldest type of transmission belt, with a history of about 100 years, but it still occupied about half of the market share of transmission belts until the middle of the 20th century. Because of its simple structure, convenient transmission, unlimited distance and easy adjustment and replacement, it is widely used in various industrial and agricultural machinery. Generally, the width of flat belt is 16-600mm, the length can reach 100-200 m, and the maximum number of layers can reach 6. Canvas belt is the most common kind of belt, which can be divided into three types: cladding, laminating and overlapping. Laminated belt is an improved product of composite belt (also known as round edge belt), which has the advantages of soft belt body, elasticity and good bending resistance. It is suitable for small pulleys and fast transmission devices with speed greater than 20 m/s, and the overlapping belt is between them, which is used for transmission with easily worn edges. Due to the low efficiency of flat belt drive (generally about 85%) and the large occupied area, the output of all countries in the world has been declining year by year since the 1960s. At present, in developed countries, except some agricultural machinery and textile machinery are still used in small quantities, they have been eliminated. On the other hand, during this period, great progress has been made in the world in joint-free endless belts and hot joints made of chemical fiber canvas and curtain cloth. It has the characteristics of high strength, low noise, smooth transmission, smooth transportation, flexible resistance, long service life and no need for joints, and its application field has been expanding, which has become the mainstream of miniature transmission belts.

In recent years, with the rise of high-tech industry, this kind of microstrip has been widely used in computer peripherals, office automation equipment and labor-saving equipment. Such as automatic ticket vending machines, ticket vending machines, money changers, ticket vending machines, cash machines, bank settlement machines, automatic inspection machines, photocopiers, medical devices, automatic packaging machines, fish detectors, etc. The United States, Japan, Europe and other countries are growing at a double-digit rate every year.

This high-performance seamless flat belt has developed into three types: polyurethane belt, polyurethane core belt and rubber canvas core belt. In rubber microstrip, besides chemical fiber canvas, there are also special products with nylon diaphragm, aramid cord and glass fiber cord as the core and chrome leather coated with rubber. They are essentially different from the traditional canvas flat belt, with very accurate specifications and high added value. The world's major belt manufacturers are competing to develop and have become high-tech products in the rubber industry. At present, Germany's Kinkling, Switzerland's Habakki, Rado and Japan's Xintian are all well-known large enterprises in this field, and the leading products are high-grade special microstrip mainly made of polyurethane.

Flat drive belt of world famous brands;

1. Ziglin.

3. Germany Wei ambition ⅵ belt

3. Habasit Switzerland.

4. Nita in Japan

triangle belt

V-belt, also known as V-belt, is the product with the largest output, the largest variety and the widest application in transmission belt. Starting from 19 17, automobile fan belts were first made in the United States, and they were widely used in industrial and agricultural machinery in the early 1920s. After more than half a century of vigorous development, it has now become the mainstream of transmission belts. As far as rubber consumption is concerned, V-belt accounts for more than 65%, toothed belt accounts for 25% and flat belt accounts for less than 65,438+00%. At present, V-belt has become the main equipment for power transmission and speed change of various mechanical devices in the world, and plays an increasingly important role in a wide range of fields such as agricultural machinery, machine tools, automobiles, ships and office equipment.

According to the cross-sectional size, V-belts can be divided into seven industrial models: Y, O, A, B, C, D and E for industrial machinery, and various fan belts for automobiles and tractors. Y-type and O-type are the smallest V-type belts, which are mainly used in office equipment such as typewriters and book cutters and household appliances (washing machines, juicers and vacuum cleaners). With the increase of horsepower, V belts such as A, B, C, D and E are used in general industrial machinery, among which D and E are heavy belts, which are used in large machinery such as ships and electric power. As for the fan belt, in addition to cars and tractors, it is also widely used in water pumps and air conditioners. In developed countries, the output ratio of V-belt to fan belt has reached the level of 2: 1-3: 2, and fan belt shows an obvious upward trend.

V-belts generally refer to winding V-belts. Since 1960s, it seems that dressing V-belt can improve the durability of transmission belt. This trimming V-belt has developed rapidly because there is no cloth on the side of the belt structure, the belt body is very soft and the bending fatigue resistance is very good. In 1980s, in order to solve the problem of transmission efficiency and service life reduction caused by different lengths of multiple V-belts in group transmission, a number of V-belts fixed together by flat belts appeared. V-shaped flat belt, which used to be called combined V-belt, has great advantages, so the phenomenon that V-shaped flat belt replaces wrapped V-belt and trimmed V-belt begins to appear again. Although there are special requirements for pulley grooves, this kind of adhesive tape combined with V-belt and flat belt has the advantages of thin belt body, large contact area with pulley, good flexibility, reduction of pulley, etc., which can further miniaturize the transmission device, save energy and increase the output of developed countries in the world.

In recent years, in order to meet the special needs of various transmission devices, in addition to ordinary standard V-belts, a large number of special V-belts with different shapes have appeared, mainly including:

(1) narrow v-band and wide v-band

The width-height ratio of the common triangle is 1: 1.5 ~ 1.6, and the narrow and wide triangles are 1: 1.2 and 1: 2 respectively. Compared with the common V-belt, the structural size of narrow V-belt can be reduced by about 50%, which can save a lot of raw materials, and at the same time, it has uniform strength, large effective contact area and small bending stress, which can greatly prolong the service life. The transmission efficiency of narrow V-belt can reach 90%-97%, the limit speed can reach 40-50m/s, and the transmission capacity is increased by 0.5- 1.5 times. It is most suitable for short-distance and small pulley stepless transmission, so it is also called stepless speed change belt. It is characterized in that the upper and lower surfaces of the belt are mostly made into single-sided or double-sided arc or tooth-shaped state, which is convenient for speed regulation. Mainly used for low-speed conical and disc CVT.

⑵ Triangle belt with small angle and large angle.

The main difference between it and ordinary triangle belt is that the included angle of 40' is changed to about 30' and 60'. Small angle V-belt can reduce the contact surface, reduce the required tension and prolong the service life, which is suitable for small tension transmission of equipment. Large-angle V-belt is a hexagonal belt with rectangular upper part and inverted trapezoid lower part, which can reduce friction loss, increase bearing capacity and make the belt soft, and is suitable for high-speed transmission of light and small equipment.

(3) Loose and perforated triangle belt

The movable belt is formed by connecting a plurality of small sections with metal screws. The punching belt is punched with many equidistant through holes in the longitudinal direction of the belt body to connect the joints. These V-belts are all spliced V-belts, which can be freely spliced and fixed according to the required length. It makes up for the limitation that the common V-belt has no joint and can only be used according to the specified length. Another advantage is that in use, when the V-belt body is partially damaged, the damaged part can be replaced for continuous use, and at the same time, the length adjustment is simple and free. However, due to its low strength, it can only be used for low-speed transmission, and it is less and less used in recent years due to problems such as low precision and poor transmission efficiency.

In addition, the V-belt, which is specially used to drive the fans of various internal combustion engines such as automobiles and tractors, is called the fan belt. It is characterized by one-time use, small pulley, short transmission distance and constant speed and power. It is a V-belt with high contact temperature and harsh environmental conditions. Fan belts are also commonly used in generators, compressors, power pumps, etc. Because the performance requirements of fan belts are completely different from those of ordinary V-belts, they are classified and counted separately in industry. In recent years, the development of fan belts in the world is very rapid, and the number has accounted for one-third of the total number of V belts.

Fan belts are divided into ordinary and narrow types, and subdivided into winding flat-bottomed V-belts, fan-shaped V-belts, trimming flat-bottomed V-belts and corrugated V-belts. The structure of fan belt is generally more complicated than that of common V belt. As shown in the attached figure, in addition to the strength layer, tensile layer, compression layer and cloth layer, a buffer layer and a support layer are added.

At present, the trimmed V-belt is widely used, which has the advantages of low heating, fast heat dissipation, large friction, low noise, good strength and high efficiency, and the driving mileage can reach18 ~ 200,000 kilometers, which is about twice as high as that of ordinary fan belts. In recent years, with the improvement of automobile engine efficiency and the emergence of rotary engines, as well as the increase of hydraulic steering devices and air-conditioning devices, the requirements for fan belts have become more and more demanding. Not only the pulley is miniaturized, but also the bidirectional double-sided driving mode is adopted more and more. Therefore, rubber and core materials have also undergone major changes.

Annular belt

The endless belt is a transmission belt with a circular cross section, which can be bent and driven freely. This kind of belt is mostly made of polyurethane, usually without core, with the simplest structure and convenient use. The endless belt has opened up a new way of belt transmission, and the demand for small machine tools, sewing machines and precision machinery in the world has increased sharply, which has great potential in the future.

Cone belt

Toothed belts, also known as synchronous belts, are divided into single-sided toothed belts and double-sided toothed belts. The former is mainly used for single-shaft transmission, and the latter is multi-shaft or reverse transmission, which is another new type of high-efficiency transmission belt in the world after 1980. According to the shape of the teeth, the toothed belt can be divided into two types: trapezoid and arc, and the arc-toothed synchronous belt bears the largest torque. According to the materials used, toothed belt can be divided into rubber type and polyurethane type, while the former can be divided into ordinary rubber (usually chloroprene rubber) and special rubber (mostly saturated nitrile rubber). Their structure consists of a strong layer made of steel cord or glass fiber and an outer rubber layer or polyurethane rubber layer made of rubber and nylon cloth.

Toothed belts, including V-ribbed belts, have developed rapidly in industrialized countries in recent 20 years, eroding the traditional markets of flat belts and V-belts in metal gears, chains and rubber. At present, it has been widely used in automobiles and traditional industries, and further extended to the transmission of precision machinery such as OA machines (office equipment) and robots. Because of the elastic teeth on the inner side of the belt, synchronous transmission can be realized without slipping, and it is lighter than the chain and less noisy. At present, more than 80% cars in Europe and 40% cars in the United States have installed this toothed belt. In 2000, China produced 2 million cars and needed more than 7 million toothed belts. Compared with the square toothed belt, the nearest circular toothed belt further increases the transmission force and quietness. As a new generation of environmental protection belt, its application scope has become more extensive. Now it has been used by sewing machines, typewriters and photocopiers for home and industry. These devices have extremely strict requirements for synchronous transmission and noise.