I. General Situation of bearing industry
1. Development of bearing industry
Bearing is the bearing shaft parts, known as "mechanical joints", is an indispensable part of modern mechanical equipment. The main function of bearings is to support rotating shafts or other moving bodies, guide rotating or moving movement and bear the load transmitted from the shaft or shaft parts.
The bearing industry in modern industry rose from the late nineteenth Century to the early twentieth Century. Since the 1950s, with the rapid development of high and new technologies such as aerospace, nuclear energy industry, computer, optoelectronic and electromagnetic instruments, precision machinery and so on, the world bearing industry has entered a period of comprehensive innovation, rapid development of manufacturing technology, variety, bearing precision, performance, life is increasingly mature and perfect.
Before 1960s, the bearing industry was mainly monopolized by European and American countries. Since the 1960s, Japan has gradually replaced the monopoly of European and American countries in the field of micro and small bearings. After entering the 1990s, with the continuous progress of China's production technology, in the field of micro and small bearings, Chinese bearing enterprises began to compete with foreign enterprises in an all-round way.
According to the statistics of the State Bureau of Statistics, the main business income of China's bearing industry from January to October 2015 was 225.549 billion yuan, and that of 2014 was 274.1 billion yuan, an increase of 225.5 billion yuan and a compound growth rate of 18%. Bearing growth is expected to slow in the future, but because bearings are essential components of machinery, the growth rate will not be lower than GDP growth.
2. Classification of bearing products
Bearing product specifications and models are numerous, according to the product structure and working principle of the different, can be divided into "rolling bearing" and "sliding bearing" two major categories. Rolling bearings refer to bearings which contain rolling elements for rolling motion between parts, while sliding bearings are bearings that do not use rolling elements and only work under sliding friction.
Rolling bearing has the advantages of low friction coefficient, high transmission efficiency and good mechanical performance, and is the dominant type of bearing industry. Rolling bearings have been standardized, serialized and universal, suitable for mass production and supply, and promoted the overall development of the bearing industry.
The sliding bearing has the advantages of small volume, high bearing capacity, small vibration, low noise, and many structural changes. Therefore, the sliding bearing has obvious advantages over the rolling bearing in the situation of large load, compact structure and impact load. The advantages of the variable structure of sliding bearing also make it applicable to various mechanical parts of different shapes.
According to the different lubrication materials and lubrication methods, sliding bearings can be further divided into "self-lubricating bearings" and "general sliding bearings". The traditional sliding bearings need to add lubricating materials such as lubricating oil and grease before or during work, so as to form a fluid or semi-fluid film on the friction interface and play an effective role in lubrication. It is called "general sliding bearing". For example, thick walled bushing and thin wall bearing are all general sliding bearings. Self-lubricated bearings are a new type of sliding bearings, which are sealed with self-lubricating materials as lubricants or pre-filled with lubricants, and can be used for a long time without adding lubricants. The bearings made of solid self-lubricating materials are also called oil-free bearings because they do not need to add traditional lubricants such as oil and grease. At present, the main materials used to make self-lubricating bearings in the world are copper, steel and other metal materials and non-metallic materials, such as polymer products (PTFE), graphite and so on.
Two. General situation of sliding bearing industry
1, China's sliding bearing industry status quo
Domestic manufacturers need to improve their R & D and innovation capabilities.
In mechanical products, bearings are high-precision products, not only need the comprehensive support of mathematics, physics and many other disciplines, but also need materials science, heat treatment technology, precision machining and measurement technology, numerical control technology and effective numerical methods and powerful computer technology and many other disciplines for its service, high-end. Journal bearing technology is more demanding for accuracy and accuracy. Because most of the bearing enterprises in China lag behind the international leading enterprises in R&D investment, innovation system construction and operation, personnel training and other aspects, bearing precision, life, noise and other related factors have not fully met the requirements of high-end machinery, therefore, in aerospace, high-speed railway passenger cars, high-grade cars, calculations. Many bearings on machines, air conditioners, high-pressure load-bearing machinery, high-speed machine tools and other equipment need to rely on imports. With the technological input and equipment improvement of bearing enterprises, bearing independent innovation capability will be greatly strengthened, innovative products are expected to replace imported products and replace traditional products.
2, development trend of sliding bearing in China
(1) improving the technical content, efficiency, reliability and accuracy of products is the general trend.
According to the product structure of bearing industry in our country at present, the production capacity of ordinary bearings with low technology content is more sufficient; and bearings with high precision, high technology content and high added value have particularity and can meet the special working conditions of self-lubricating bearings, regardless of the variety or quantity, there is great room for development. From the perspective of product quality and technology level, China still needs a large number of imported high-end bearings every year.
Improving the R&D, design and manufacturing capabilities of journal bearing manufacturers is the only way to achieve high technology content, high reliability, high efficiency and high precision of Journal bearings. With the support of the national policy and the rapid development of China's equipment manufacturing industry, it is expected that the future sliding bearing industry enterprises will focus on improving the precision, performance, life and reliability of bearing products. The manufacturers of sliding bearings in China continuously improve the level of R&D, design and manufacture by increasing R&D efforts and introducing foreign advanced manufacturing equipment, which is in line with the inevitable trend of future industry development.
(2) further specialization based on market segmentation.
Sliding bearings, especially self-lubricating bearings, are of many varieties and specifications because of their different uses. Different types of journal bearings have different requirements for heat treatment level, turning accuracy, surface treatment, automation of production equipment and manufacturing process, so the existing journal bearing enterprises are basically focused on a specific field or market segmentation. After hundreds of years of development, the international bearing industry has formed a stable specialized division of labor. The international bearing giants organize specialized production in their respective market segments. In the future, the domestic journal bearing production enterprises will further clarify the product positioning, take the road of specialization and division of labor, strengthen the fine market division, and realize the scale effect.
(3) the research and development ability of lubricating materials plays an important role in the design and production of journal bearings.
The surface material and lubricity of sliding bearing determine the properties of wear resistance and compression resistance. In order to meet customer needs, different types of sliding bearings have different requirements for surface materials, so the research and development ability of sliding materials for sliding bearing enterprises largely determines the speed of business expansion. Future sliding bearing enterprises will further increase the development of sliding materials to meet the needs of production and operation.
Three. General situation of self lubricating bearing industry
1. Development of self lubricating bearings
The manufacturing technology of self-lubricating bearings originated in England. PTFE (polytetrafluoroethylene) was tested as a bearing material in Britain in the 1950s, and the sintering process of copper powder was also a breakthrough. In 1956, the world's first PTFE-lined, steel-supported self-lubricating DU bearings were put on the market. At the end of the 60s, self lubricating bearings began to enter the application fields of advanced science and technology, such as aerospace. Since the 1970s, the British manufacturer of self-lubricating bearings has licensed technology to French, German, Japanese and American companies. This initiative has promoted the rapid development of the world self-lubricating bearings industry. Self-lubricating bearings have gradually entered all the machinery manufacturing fields.
2. Classification of self lubricating bearing products
With the development of the self-lubricating bearing industry, the production process and materials of self-lubricating bearings are constantly innovated, and the types of products are gradually rich. According to the different product structure and manufacturing materials, self-lubricating bearings are divided into three categories: multi-layer type, single-layer type and other three categories, which are divided into several subcategories. The following are as follows:
"Multi-layer" self-lubricating bearing products are composed of two or more different types of bearing materials, in which the lining material plays a self-lubricating role, the substrate plays a supporting role, and other materials play a connecting and transitional role. The lubrication effect of the laminated product is excellent, and its bearing capacity is determined by the compressive strength of the surface material. According to the types of substrate and lining materials, it can be divided into metal substrate and metal lining layer, metal substrate and non-metal lining layer, and non-metal substrate and non-metal lining layer.
"Single-layer" self-lubricating bearing products are made of a type of bearing materials, the products rely on bearing materials containing self-lubricating materials such as graphite, molybdenum disulfide, polytetrafluoroethylene, lead to lubrication, according to the type of bearing materials, can be divided into metal and non-metal categories. Non metallic single layer self-lubricating bearings mainly include integral non-metallic bearings, non-metallic rolling bearings, etc. Metal monolayer bearings mainly include solid mosaic products and oil-bearing products. "Solid mosaic" self-lubricating bearing is a kind of self-lubricating bearing, in which some holes or grooves are pre-processed according to a certain arrangement on the metal substrate, and then solid lubricant is embedded in it; during the working process, due to friction heat or environmental temperature, solid lubricant is slightly prominent on the sliding surface, and rubbed on the metal substrate and on it. The transfer film is formed on the even surface to play a role of friction reduction and wear resistance. "Oil-containing" self-lubricating bearing is a porous material made of metal powder pressed and sintered by powder metallurgy process, and then filled with lubricating oil in the pores; during the working process, lubricating oil is precipitated from the bearing due to friction heat or ambient temperature, and lubricating oil film is formed on the metal substrate and the dual surface. To reduce friction and wear.
3. Characteristics of self-lubricating bearing products
Self lubricating bearings are suitable for places that cannot be refueling or difficult to fill. Because of the requirement of special production technology, some key equipments in automobile manufacturing and machinery industry need to operate under extreme working conditions. It is difficult to add lubricating oil to the equipments because of heavy equipment, high ambient temperature, large dust or acid corrosive gas in the air. Therefore, the friction between rolling bearings and ordinary sliding bearings is very difficult. Serious wear and tear, bearing bite or bite to death, causing parts wear and damage, resulting in equipment outage. In order to produce continuous operation, in addition to the original design requires the installation of a number of equipment rotation, but also need to invest a large number of maintenance personnel, spare parts and energy consumption is enormous. Therefore, automobile manufacturing, construction machinery, mold industry and other enterprises have the demand for special lubricating materials under complex working conditions. No oil can greatly simplify the design and structure of bearings, reduce costs, save design time, can be used in bearings without maintenance or less maintenance, but also avoid the risk caused by insufficient oil supply. Through the study of self-lubricating bearing composite materials and self-lubricating bearings, the issuer has achieved innovative breakthroughs in material formulation and manufacturing technology, which can solve the lubrication problems under special working conditions for customers.
Since self-lubricating bearings do not require oil supply devices, and can be operated without oil, they can save a lot of installation and operation costs, improve mechanical performance, improve service life and reliability. The oil-free treatment does not require the recovery of waste oil, and is also conducive to environmental protection. Self lubricated bearings have lower requirements for the hardness of the grinding shaft, thus reducing the machining difficulty of the relevant parts. The self-lubricating composite bearing structure can be plated with various metals on the surface, and can be used in corrosive medium. In addition, since oil-free lubrication does not exist the problem of oil volatilization, self-lubricating bearings can be used in high temperature and high pressure environment.