The moving belt is the power generated by the rotation of the motor or engine of the prime mover, and is transmitted from the belt to the mechanical equipment through the pulley. It is also called the power belt. It is the core connection component of electromechanical equipment. It has a wide range of types and applications. From huge motors up to thousands of kilowatts, to micro motors less than one kilowatt, and even to precision machinery such as home appliances, computers, robots, etc., there is no need for a belt. Its biggest feature is that it can be freely variable speed, far and near drive, simple structure, easy to replace. Therefore, from the original machinery to the modern automatic equipment has a belt figure, the product has evolved many times, the technology is maturing.
There are various forms of power transmission such as chains, gears, and couplings (couplings). However, considering the economy and cost, so far, there has been no adhesive tape for elastomers. Therefore, most of the transmission methods in the world are still mostly based on tape transmission, and their development is still expanding.
The belt was originally made of leather and replaced by rubber in the middle of the 19th century. In the 1960s, NR and SBR were gradually turned to CR and PUR. In the 1980s, it was further expanded to adopt CSM and HNBR. The shape of the tape also depends on the expansion of the plate type to the angle, round, and tooth type. The use of a single drive to a group of parallel connections has led to the formation of today's belt series.
I. Development status
The transmission has two functions of transmission and speed change, and is divided into two categories: friction drive and meshing drive. So far, the world's drive belt manufacturing plants have formed four systems of V-belts, flat belts, toothed belts, and round belts in their structural shapes, including more than 1,000 types including size specifications. In particular, toothed belts, in the last decade or so, with the advancement of precision machinery and electronic information technology, as the high-tech products of the rubber industry, it has been developing rapidly throughout the world, and the output has been expanding rapidly. The classification of transmission belts.
1, flat belt
The flat belt is the oldest type of transmission belt and has a history of more than 100 years. However, it still occupied about half of the market share of the transmission belt until the middle of the 20th century. It is widely used in various industrial and agricultural machinery because of its simple structure, convenient transmission, no distance limitation, easy adjustment and replacement. Flat belt width is generally from 16-600mm, the length of up to 100 ~ 200m, the maximum number of layers 6 is the most common canvas belt, divided into clad, laminated and stacking three. The laminated belt is an improved product of a cladding belt (also called a round belt), which has the advantages of softness, elasticity, and good bending resistance, and is suitable for use on small pulleys and quick transmission devices of 20 m/s or more. . The stacking belt is interposed between the two and is used for the transmission of the edges susceptible to wear. Due to the low transmission efficiency of the flat belt (usually about 85%) and the large area occupied, the production of various countries in the world has declined year after year since the 1960s. At present, in developed countries, except for a small amount of agricultural machinery and light textile machinery, it is in a state of being eliminated. On the other hand, in this period, endless joints and thermal joints made of chemical fiber canvas and cords as cores have achieved considerable development around the world. It is characterized by its high strength, low noise, smooth transmission, smooth transportation, resistance to flexion, long service life, and no need of joints, etc. The field of use is continuously expanding, and it forms the mainstream in the micro drive belt.
In recent years, with the rise of high-tech industries, such micro-bands have been commonly used in computer peripheral equipment, office automation equipment, and labor-saving equipment. For example, automatic ticket gates, automatic ticket vending machines, currency exchange machines, coupon issuing machines, cash machines, bank settlement machines, automatic inspection machines, copiers, medical equipment, automatic packaging machines, fish school detectors, etc., countries such as the United States, Japan, and Europe. Each year grows in double figures.
This high-performance jointless flat belt has now been developed into three types of polyurethane belts, polyurethane core belts and rubber canvas core belts. In addition to chemical fiber canvases, there are also special products that use nylon membranes, aramid cords, glass fiber cords as cores, and chrome-covered surface rubbers. They are essentially different from the traditional canvas flats. The specification requirements are very precise. The added value is very high. The world's major tape manufacturers compete for development and have become high-tech products in the rubber industry. At present, Germany's Jin Yulin, Habaji of Switzerland, Radar, and Japan's Xintian are all well-known large enterprises in this field, and have used polyurethane-based high-end and special micro belts as their leading products for full development. .
2. Triangle belt
The V-belt, also known as the V-belt, is a product with the largest output, the most variety, and the widest use in the transmission belt. Since it was first made from the United States in 1917, it has been used as a fan belt in the industry. Since its introduction in the early 1920s, it has been used for many years. It has been prosperous for more than half a century and has developed rapidly. It has now become the mainstream of transmission belts. In the transmission belts of various countries in the world, from the viewpoint of the amount of rubber used, the V-belt has now accounted for 65%, the toothed belt is 25%, and the flat belt has been reduced to less than 10%. At present, the V-belt has become the main equipment for power transmission and transmission of various mechanical devices in the world. It 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 section size, the triangle belt can be divided into seven industrial models Y, O, A, B, C, D, E for industrial machinery and various types of fan belts for automobiles, tractors, etc., and there are two major categories. Y and O are the smallest V-belts and are mainly used for typewriters, book cutters and other office equipment and home appliances (washing machines, juicers, vacuum cleaners). In general industrial machinery, as the horsepower increases, V-belts such as A, B, C, D, and E are sequentially used, among which D and E are heavy-duty belts, and are used for large-scale machinery such as ships and electric power. As for the fan belt, it is also used in pumps, air conditioners, etc. in addition to automobiles and tractors. In developed countries, the production ratio of the V-belt to the fan belt has reached a level of 2:1-3:2, and the fan belt has shown a significant upward trend.
The triangle belt generally refers to the wrapping type V-shaped belt. Since the 1960s, in order to improve the durability of the transmission belt, a cut-edge V-shaped belt has emerged. This kind of trimmed V-belt, because the side of the tape structure has no wrapper, the belt body is very soft, and the flex fatigue performance is very good, so it is rapidly developed. In the 1980s, in order to solve the problem of transmission efficiency and reduced service life caused by the inconsistency of multiple transmissions in the V-belts, a number of V-belt belts relative with flat belts have emerged. The V-shaped flat belt that is used to be called a connecting triangle belt has a great advantage, and thus the phenomenon that the V-shaped flat belt replaces the wrapping type and the trimming-type triangular belt has begun to appear. This kind of tape with V-belt combined with flat belt has special requirements on the pulley groove, but due to the thin belt body, the contact area with the pulley is large, the bending is good, the pulley is reduced, and the transmission device can be further With miniaturization and energy saving, the production volume in developed countries in the world has increased dramatically.
In recent years, in order to meet the special needs of various transmission devices, in addition to the common standard type of V-belt, there are also a large number of special triangular belts of various shapes, which mainly include:
(1) Narrow and Wide V-belt
The aspect ratio of the common triangle belt is 1:1.5 to 1.6, and the narrow and wide triangle belts are 1:1.2 and 1:2, respectively. The narrow V-belt can reduce the structure size by about 50% compared with the ordinary V-belt. It can save a large amount of raw materials, at the same time strong and uniform, effective contact area, small bending stress, and can greatly extend the service life. Narrow V-belt transmission efficiency of up to 90% to 97%, the limit speed of 40-50m / s, transmission capacity increased by 0.5 to 1.5 times, the most suitable for short-distance, small pulley in the transmission, so Also known as the transmission belt. Its characteristics are in the upper and lower surfaces of the belt, mostly made of single-sided or double-sided curved or toothed state, making it easy to speed, mainly used in low-speed cone-type and disc-type continuously variable transmission.
(2) Small Horn and Big Horn Triangle
Its main difference with the ordinary triangle belt is that the angle 40` is changed to about 30` and 60`. The small angle V belt can reduce the contact surface, reduce the required tension, extend the service life, and adapt to the small tension of the device. The V-Belt is a rectangle with an upper half, and an inverted trapezoidal Hexagon in the lower half. It can reduce the friction loss, increase the carrying capacity, and make the belt soft. It is suitable for high-speed transmission of light and small equipment.
(3) Active and washed L-shaped belt
The active belt is made up of a plurality of small pieces joined by metal screws. The punching belt is punched in the longitudinal direction of the belt body with a plurality of equidistant through holes for connecting the joints. This type of V-belt is a V-belt that can be jointed, and can be freely lengthened according to the required length. It makes up for the limitation that the common V-belt has no joints and can only be used in accordance with the specified length. Another advantage is that, in use, when the V-belt body is partially damaged, the replaceable damage site can be used continuously, and at the same time, it has the advantage of being able to simply and freely adjust the length. However, because of its low strength, it can only be used for low-speed transmission, and due to problems such as low accuracy and poor transmission efficiency, it has been declining in recent years.
In addition, the V-belt that is used for designating various internal combustion engine-driven fans for automobiles, tractors, etc., is specifically called a fan belt. It is characterized by single-use, small pulleys, short transmission distances, and constant changes in speed and power. It is a type of V-belt that has a high contact temperature and is used under harsh environmental conditions. Fan belts are also commonly used in generators, compressors, power pumps and so on. Because of its performance requirements, the fan belt is completely different from the ordinary triangle belt, and the statistics are separately classified in the industry. In recent years, the development of the fan belt in the world has been very rapid, and the number has accounted for one-third of the total number of triangular belts.
The fan belts are divided into two types, ordinary and narrow, and are subdivided into various types, such as flat cloth-type V-belts, round-toothed V-belts, cut-edge flat-bottom V-belts and wave V-belts. The structure of the fan belt is generally more complex than that of an ordinary triangular belt. Referring to the drawings, a buffer layer and a support layer are added in addition to the strength layer, the extension layer, the compression layer, and the clad layer.
The most widely used is the edge-wavy V-belt, which has low heat generation, rapid heat dissipation, high friction, low noise, good strength, and high efficiency. The mileage can reach 18 to 200,000 kilometers, which is about twice as high as the average fan belt. . In recent years, with the increase in the efficiency of automotive engines and the emergence of rotary engines, and the increase in the number of hydraulic steering devices and cold air devices, the requirements for fan belts have become increasingly severe. Not only are belt pulleys compact, but also the use of two-way two-sided drive The more, therefore, the rubber and the core material also have a significant 舀I~, ¡IIIIit ordinary V-belts, V-shaped flat belts and fan belts compared 1 - on the adhesive layer: 2- adhesive layer; 3- rubber stretched Layer: 4-rubber compression layer: 5-strand strength layer; 6-rubber cushion layer: 7-~tgrg
3, circular belt
The round belt is a belt with a circular cross-section, which can be flexibly driven. This type of belt is mostly made of polyurethane and usually has no core. The structure is the simplest and it is easy to use. Circular belts have opened up new avenues for the transmission of tapes. The use of small machines, sewing machines, precision machinery, etc. in various countries in the world is rapidly increasing. There is great potential in the future.
4, tooth belt
The tooth belt is also called a timing belt and is divided into two types: single-sided toothed belt and double-sided toothed belt. The former is mainly used for single-axis transmission, and the latter is multi-axis or reverse transmission, which is another new type of high-efficiency transmission belt emerging from the world since 1980. The toothed belt is divided into trapezoidal and circular arc shapes according to the shape of the teeth, and the torque received by the timing belt of the arc-shaped teeth is the maximum. From the materials used, toothed belts can be divided into two major categories: rubber and polyurethane, while the former has common rubber (usually neoprene) and special rubber (mostly saturated nitrile rubber) points. Their structure consists of a strong layer made of steel cords or glass fibers and an outer rubber layer or polyurethane layer made of rubber and nylon cloth.
The toothed belts include V-ribbed belts, which have been developing extremely rapidly in industrial developed countries in the past 20 years and are continuously eroding the traditional flat metal belts and chains in the metal gears, chains, and rubber markets. At present, in addition to being widely used in automobiles and traditional industries, it is further expanded to the transmission of various precision machinery such as OA machines (office equipment) and robots. Because the inner side of the tape is equipped with elastomeric teeth, it can achieve synchronous drive without sliding, and it is lighter and less noise than the chain. Nowadays, more than 80% of cars in Europe and 40% of cars in the United States have installed such teeth. Belts. In 2000, China produced 2 million cars and more than 7 million toothed belts. The recent appearance of the scalloped spur belt has further increased the transmission force and quietness compared with the spur toothed belt. As a new generation of environmental protection belts, the scope of its use is more extensive. Nowadays, it has become the target for home and industrial sewing machines, typewriters, and copiers, which have extremely stringent requirements for synchronous transmission and noise.