1. Classification of ceramic bearings and ceramic ball bearings
According to the material: ceramic bearings can be divided into zirconia ceramic bearings, silicon nitride ceramic bearings, composite ceramic materials bearings.
According to the structure: ceramic bearings can be divided into: zirconia with retainer ceramic bearings, silicon nitride with retainer ceramic bearings, composite belt retainer ceramic bearings. The general ceramic bearing retainer material is made of polytetrafluoroethylene (PTFE) as standard. It can also be made of glass fiber reinforced nylon 66 (GRPA66-25), special engineering plastics (PEEK, PI), stainless steel (SUS316, SUS304). Brass (Cu), etc. Ceramic material cages are still less used due to problems such as pocket processing and forming technology; due to the material limitations of the holders, the zirconia full ball ceramic bearings and silicon nitride balls without cages have been developed for special applications. Full ceramic bearings and composite full ball ceramic bearings.
According to the integrity of the material: the main components of the ceramic bearing mentioned above, the inner and outer rings and the rolling elements are mostly ceramic materials, which are defined as ceramic bearings; if the inner and outer rings of the bearing and the rolling elements are not ceramic materials, we It is defined as a hybrid ceramic bearing. The widely used hybrid ceramic bearing is that the ball is made of ceramic material called ceramic ball bearing, which can be divided into zirconia ceramic ball bearing and silicon nitride ceramic ball bearing.
The problems that need to be paid attention to when using ceramic bearings and ceramic ball bearings of different materials and different structures are also different.
2. Overview of research and development of domestic and foreign ceramic bearings and ceramic ball bearings
Ceramic bearings and ceramic ball bearings are a wonderful combination of new types of bearings, which are a perfect combination of new processes, new materials and new structures. As a basic part of the rotation of the carrier machinery, it has excellent performance unmatched by metal bearings. It is widely used in various special environments and harsh environments. Because it has high temperature resistance, low cold resistance, corrosion resistance, electrical insulation, magnetic resistance, low density and high strength, it is the leader in the new material world. In the past ten years, it has been widely used in various fields of national economy and people's livelihood. In the fields of aerospace, navigation, nuclear industry, petroleum, chemical, textile industry, machinery, metallurgy, electric power, new energy, food, locomotive, subway, high-speed machine tools and scientific and technological defense, we need high temperature, high speed, deep cold, It is flammable, explosive, strong corrosion, vacuum, electrical insulation, non-magnetic, dry friction, easy to rust and other special working conditions. The indispensable substitute effect of ceramic bearings is gradually being recognized. With the continuous advancement of processing technology and the increasing level of technology, the cost of ceramic bearings has been declining. From the past, it has only been applied in a small range of high, fine and pointed fields, and gradually extended to various industrial fields of the national economy. Production makes the market price gradually close to practical use, reaching the level acceptable to users. Through the batching and long-term use test of different industries, many successful cases have experienced the maintenance-free and long life brought by ceramic bearings and ceramic ball bearings. The advantages of high stability and low cost. Ceramic bearings and ceramic balls have gone from the research and trial production stage to the mass production stage, and the wave of large-area application has already arrived.
Third, the development status of foreign ceramic bearings and ceramic ball bearings P5fp G+x4a0
3R;N (e&i2r: P0's first ceramic bearing was born in NASA. Since the first ceramic bearing was successfully developed in 1972, countries around the world have been competing to develop and develop a new generation of higher performance ceramic bearings. After nearly four years of hard work, the most outstanding effect of ceramic bearings is to greatly increase the service life and limit speed of the bearings, providing basic components for the development of high-speed and ultra-high-speed, high-precision machine tools. High temperature, corrosion, insulation, vacuum, chemical and other industries have also achieved good results. Today's world-famous bearing companies are all research and development, production of ceramic bearings and ceramic ball bearings, and the quality of products has become a measure of its business. An important symbol of strength. According to incomplete statistics, so far, foreign countries can produce ceramic bearings: the United States, Japan, Germany, France, Russia, South Korea, the United Kingdom and other countries. Among them, the production of ceramic ball bearings is abroad. It started earlier and has a wide range of applications, such as ceramic ball bearings for CNC machine tools and ceramic ball bearings for electric spindles for grinding machines. Ceramic ball bearings for ball-type ball screws, etc. Ceramic ball bearings have been fully utilized for their high wear resistance, self-lubricating properties, and high-speed rotation. They have also contributed to high-precision machine tools, high-speed machine tools, and special environmental equipment. As the core component of ceramic ball bearing---ceramic sphere, foreign R&D and competition are fierce. The ceramic ball produced by Norton Company of the United States using HIP method is at the international level. Currently, the world's research ceramic ball bearings are leading. The main companies in the level are SKF in Sweden, FAG in Germany, Saint-Gobain in France, NSK in Japan, KOYO, and NMB.
Fourth, the development status of domestic ceramic bearings and ceramic ball bearings
1. Ceramic bearings started late in China. At present, the universities and institutes that research and develop ceramic bearings and ceramic ball bearings in China are all: Shanghai Institute of Ceramics, Shanghai Materials Institute, Shandong Institute of Ceramics, Guangdong University of Technology, Tianjin University, Luo axis and so on. Domestic ceramic bearing manufacturers are mainly distributed in Beijing, Shanghai, and Zhejiang. In addition to some samples made by Luo axis and Shanghai silicate, no industrialized enterprises have been seen. Compared with foreign countries, the development of China's ceramic bearings is not optimistic. There are almost no domestic enterprises that can form industrial scale production of ceramic bearings. The root cause is of course the influence of various factors, such as technical level, talents, funds, etc., especially the market is unclear and lacks confidence. At present, there are still some problems in the research and development of ceramic bearings and ceramic ball bearings in China, which seriously restricts the development of China's ceramic bearings and ceramic ball bearings.
Second, the problems in the research and development of domestic ceramic bearings and ceramic ball bearings
First of all, we are currently reporting the development of high-speed, high-precision ceramic ball bearings, and usually focus on silicon nitride balls, mainly to solve the problem, one is the research of the blank of ceramic balls, and the other is High-precision ceramic ball processing technology research, in the use of high-speed machine tools, CNC machine tools, electric spindles and other high-speed occasions, long life or low noise requirements of ceramic ball bearings, from the beginning to the end can not be separated from the manufacture and processing of SI3N4 billet The research on new materials such as SiC, ZrO2, ZTA, Sialon and other materials is still a small amount, and production practice has proved that the majority of manufacturers using ZrO2. Due to cost considerations, good materials and processes cannot be used on a large scale. The low-noise, dry-friction, anti-static ceramic ball bearings produced by Haining Kangnaite Bearing Manufacturing Co., Ltd. and the ceramic ball bearings of the same specifications from NMB Japan have been detailed. The comparison, on the decibels, the difference is 2 db, good products can do 20db. The same as foreign products. But the price is positioned at around 15% of NMB. It can be directly matched with the motor of domestic household appliances. However, this price is still a lot higher than that of ordinary bearings, and can only be used in high-end and export household appliances.
Secondly, the production of ceramic bearings and ceramic ball bearings is a combination of high-tech ceramics and bearing manufacturing technology. The degree of specialization of the two is very high. If the ceramics and bearings are not solved, the quality of the products will be high and large. Cost production, meeting market demand is an empty talk. Nowadays, enterprises that can produce bearings in China cannot manufacture ceramic materials. Enterprises that can produce ceramic materials cannot manufacture bearings. The professional and disciplines are seriously out of touch in practical applications. At present, some bearing manufacturers have expertise in ceramic bearings and ceramic ball bearings. In particular, there are few studies on ceramic materials science and engineering. The surface content of ceramic bearings and ceramic ball bearings is well known. A bearing made of ceramic material is a ceramic bearing, and the addition of a ceramic ball is a ceramic ball bearing. Domestic ceramic bearings and ceramic ball bearings can only be used in environments with corrosion resistance, electrical insulation, magnetism, low speed and light load. There is also a big problem in the manufacture of domestic ceramic materials. Under the premise that the process and technology have not yet passed, the blind pursuit of low-cost materials can not achieve the expected results. The development of ceramic bearings and ceramic ball bearings has entered a new strait, and also caused more units to lose confidence in ceramic bearings and ceramic ball bearings.
Furthermore, as a high-tech product research and development, it is necessary to go through two stages of technology-intensive investment and capital-intensive investment. Industrial production of ceramic bearings requires not only many technical difficulties but also large capital investment. To grasp the market positioning, it is necessary for people of insight in the industry to develop high standards of domestic ceramic bearings and ceramic ball bearings. Low-cost competition is bound to lead to shoddy and further deterioration of the market. The accumulation of original capital and continued reinvestment must serve the development of ceramic bearings and ceramic ball bearings in higher quality fields. The current development of China's ceramic bearings is characterized by scattered, individualized, small-scale localized production lacking overall awareness and macro strategic thinking.
V. Prospects for the use of ceramic bearings and ceramic ball bearings
Ceramic bearings and ceramic ball bearings have many excellent properties such as self-lubrication, high temperature resistance, corrosion resistance, anti-magnetic, electrical insulation, etc., which have yet to be developed and utilized in a wider field, and the potential application fields are enormous. The first high-quality high-speed ceramic ball bearing: It can serve the domestic machine tool industry very well. The bearing of high-speed, high-precision spindle and electric spindle is quite large. It is estimated that the annual demand is more than tens of thousands. However, high-precision machine tool spindle bearings require relatively high machining precision and high quality. For example, P4 grade bearings require high-precision ceramic balls of G5 or higher. At present, there are few manufacturers in China, and the stability of the products is also poor. Second: medium-quality ceramic bearings in oil exploration, crude oil smelting, especially fine chemicals, chemical fiber, new energy, printing and dyeing, electroplating, sewage treatment, marine development, deep water pumps, acid and alkali pumps, high temperature, vacuum, nuclear magnetic resonance, It can be widely and used well in many fields such as electrical insulation, medical and health, X-ray tube and food industry. Many require only general accuracy grades; medium and low speeds and loads; bearings are required to withstand certain concentrations of acid, alkali, and salt corrosion; resistant to 300 to 400 ° C; non-magnetic, electrical, non-toxic; can be used without oil or The working medium is self-lubricating, etc.; it can also be used in sea water. Bearings used in these fields account for a very large proportion of special bearings, and ceramic bearings and ceramic ball bearings are fully capable of replacing and achieving the tough and incompetent work of metal bearings. Engineering ceramics have an irreplaceable position. With such a huge market as a premise, we can create a new path in the development and manufacture of products to expand the wider application of ceramic bearings. Make new materials, new processes, and new technologies better serve production.
