Types and history of V-belts
Wrapped V-belt
According to its skeleton material structure, the wrapped V-belt can be divided into wrapped cord V-belt and wrapped cord V-belt. Because the cord structure of V-belt is more reasonable than the cord structure, the stress is uniform, and the bending stress is small, the service life and performance of V-belt can be greatly improved. As early as the 1960s, the advanced industrial countries had completed the upgrading of V-belt structure rope and polyester. China did not start the large-scale structural transformation of V-belt rope until the middle and late 1990s. The wrapped V-belt can also be divided into ordinary V-belt, narrow V-belt, automobile V-belt, hexagonal V-belt and variable-speed V-belt for agricultural machinery according to its sectional shape and use requirements. Its structure is mainly composed of compression adhesive, tensile body of strong layer, adhesive, stretching adhesive and wrapping cloth.
Ordinary V-belt
Ordinary V-belt (V-belt) is the main drive belt product in China, with an annual production of more than 1 billion am, accounting for more than 80% of the V-belt output. In the 1970s, China used rayon cord fabric as the framework material. In the 1980s, polyester cord fabric was used for ordinary V-belts. In the early 1990s, the former Jiaxing rubber factory and Jiangsu Changshu elephant Rubber Industry Co., Ltd. jointly produced wire rope wrapped V-belts with Taiwan liberday company and Taiwan elephant Rubber Industry Co., Ltd. respectively. After that, China began comprehensive wire rope and polyester transformation of ordinary V-belts.
Narrow V-belt
Narrow V-belt is a new series of high horsepower V-belt developed by gates company in the 1950s. Due to its reasonable structure, uniform force on the strong layer wire rope, large transmission power and compact transmission structure, it will soon replace the ordinary V-belt as the main product of V-belt. China started relatively late. In order to solve the problem of transmission capacity of large-scale equipment in the early stage, too narrow V-belts were manufactured with rayon cord fabric. In the 1970s, the former Ministry of petroleum developed the narrow V-belt with wire rope structure to solve the belt transmission problems of oil drilling equipment and pumping units. However, due to the problems of materials, especially skeleton materials and tooling, no breakthrough has been made. In the mid-1980s, the former Ministry of petroleum, the former Ministry of machinery and the former Ministry of chemical industry jointly initiated a project to jointly tackle key problems of the combined narrow V-belt for petroleum equipment, and achieved a series of achievements. The manufacturing technology level and product quality (product performance, service life, transmission efficiency and transmission capacity, etc.) reached the advanced level of foreign countries at that time, which promoted the research and development of China's V-belt technology such as tooling, raw materials and theoretical application, The product passed the ministerial appraisal in 1987.
Automobile V-belt
In 1911, the V-belt invented by the American Gates was first used in automobiles to drive cooling fans. In the 1970s, the trimmed V-belt appeared and gradually replaced the wrapped V-belt. In the 1980s, it was completely replaced by the trimmed V-belt and the multi wedge belt. China first produced for imported auto parts in 1945. In the 1950s, the state-run Shanghai chemical plant provided the first Jiefang brand car in China according to the standards of the former Soviet Union. In the mid-1980s, some professional manufacturers of V-belts and air pump belts for automobiles and tractors in China cooperated with Nanjing Glass Fiber Research Institute (hereinafter referred to as Nanjing Glass Fiber Research Institute) to successfully develop glass fiber cord strong layer fan belts and air pump belts and put them into mass production. After use, users generally reflect that the glass fiber fan belt and air pump belt have high breaking strength, low breaking elongation, large transmission power, long service life, and can travel 40000-50000 km under normal conditions. In addition, the use of glass fiber cord as the strong layer of fan belt can solve the problem of excessive elongation in the early stage of use and prevent the tape from slipping during use. It was not until the end of the 1990s that it was completely replaced by polyester cord. At present, V-belt of automobile is basically replaced by chamfered V-belt and multi wedge belt in China.
V-belt for agricultural machinery
It refers to the transmission belt specially used for agricultural operation, horticulture, forest industry and other equipment. Its varieties and specifications include almost all V-belt varieties and a small number of flat belts and special-shaped belts. Among them, the most important is the variable-speed V-belt (endless speed belt) for the main drive of the combine. It is characterized by poor working environment (sun, rain, sand, dust, oil, etc.), low speed, high load, high impact, extreme tension and deflection, and large slip heat generation, so it forms an independent standard system. China is a large agricultural country, and the country attaches great importance to agricultural mechanization. Large scale combine harvesters are valued for their high production efficiency and adaptability to large-scale operation. The main drive stepless transmission of the combine is the key component of the combine, and the variable speed V belt is the main component. Its performance and quality will directly affect the working state of the combine. The generation V products of agricultural machinery in China started in the mid-1970s. At that time, the state put forward the idea of accelerating the realization of agricultural mechanization, introduced a large number of agricultural mechanization and other agricultural machinery from abroad, and domestic combine harvesters have also come out one after another. For the maintenance parts and supporting use of these combine harvesters, due to many problems such as production technology, raw materials and tooling, the product quality and performance could not meet the requirements. For example, the service life was less than 100 hours, and several single belts had to be replaced in each wheat season. For this reason, since the late 1970s and the early 1980s, the China Agricultural Mechanization Research Institute and relevant domestic units have cooperated to carry out a large number of research and research work, and achieved some results, such as the service life increased to more than 300 hours. However, limited to the conditions at that time, no breakthrough has been made, and the product quality stability is poor. But what is important is that a group of belt transmission research experts have emerged and developed a number of test equipment, which laid a foundation for the later development of belt transmission in China.
At the end of the 1980s, the manufacturing technology of agricultural machinery V-belt imported from the United States greatly shortened the gap between China's agricultural machinery V-belt and foreign countries. The fatigue life of HM type variable speed V-belt has exceeded 100h and the service life has reached two wheat seasons. In 1998, German Scholz technology and equipment were introduced, and the fatigue life reached 63h. The product has good effect in a wheat season and a bean harvest test. In recent years, the half feed rice combine harvester has been widely used in China, and its main technical source is Japan. In its transmission system, the reverse tension wheel (back tension wheel) is used to adjust the belt tension and the tension clutch is used. This structure is combined with the compact structure and high horsepower of this combine harvester, and the cross-section model of the V-belt is small. Among them, the wire rope of W600 and w800 belt strength layer needs aramid, and the structure and formula of the belt should be specially designed to ensure the transverse rigidity, longitudinal flexibility and heat resistance of the belt.
