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Key words: bearing wear self-repairing wear protection layer
Since the reform and opening up, the development of China's bearing industry has achieved remarkable achievements. Since 2000, according to the annual output of bearings, China has become the world's fourth largest producer of bearings after Japan, the United States, and Germany. The annual output of bearings has reached more than 2 billion sets, with an annual output value of about 24 billion yuan. Among them, the export volume accounts for more than 50% of the total output, and the annual foreign exchange earns about 700 million US dollars. In recent years, China's bearing products have also made significant progress in terms of dimensional accuracy, rotation accuracy, vibration and noise, life and reliability. However, compared with the products of foreign bearing producing countries, domestically produced bearings still have a large gap in terms of variety and quality. To further increase the variety and improve the quality, we must work hard on the comprehensive technology of bearing design, manufacturing, materials, testing and lubrication, and we need a development process. The application of metal wear self-repairing materials on domestic bearings improves the reliability of the bearings, reduces the friction coefficient between the bearing races and the rolling elements, greatly prolongs the service life of the bearings, and makes the universal bearings new to the "infinite life". The direction of the concept requires a big step forward and has significant economic benefits.
First, the quality of China's bearing products quality overview:
From 1997 to 1999, according to the “National Supervision and Inspection Product Catalogue†formulated by the State Bureau of Quality and Technical Supervision, the quality of the rolling bearings was checked. The average pass rate for the three years was 68%. In 2000, the quality of spot checks was 6 percentage points higher than that of 1999, which proved that the quality supervision and spot check management work achieved obvious results. Compared with the developed countries of bearing industry, the difference in the variety and quality of domestic bearings is mainly reflected in:
1. There are few domestically produced bearings and low output value. Bearing industry developed in developed countries, bearing varieties of 150,000, China's production of bearing varieties of only 20,000, and most of them are general-purpose products. There are more than 2,000 domestic bearing enterprises, and the total annual output value is listed in the world's five major bearing companies (SKF, NSK, KOYO, NTN, NMB). Therefore, China's bearing enterprises are small in scale and low in output value. 0.4 US dollars.
2. The dispersion of the dimensional accuracy tolerance of domestic bearings is large. Although China's bearings have made great progress in dimensional tolerance and rotation accuracy, which is close to the level of foreign famous brand products, there is still a big gap in the dispersion of dimensional deviation.
3. In terms of vibration, noise and abnormal sound, the vibration extreme value of China's bearings is higher than that of foreign famous brand products by more than 10dB. Taking the 6202 bearing as an example, the foreign famous brand products are about 26dB, and the domestic 18 bearing enterprise products are sampled, and the average value is 37.5dB.
4. The life and reliability of domestic bearings are still low. Taking deep groove bearings as an example, the life of foreign famous brand products is generally more than 8 times of the calculated life (up to 30 times or more), and the reliability is more than 0.98; the life of domestic bearings is generally 3 to 5 times of the calculated life, and the reliability is Around 0.96.
Application of metal self-repairing materials on bearings
Abstract: The metal wear self-healing material is composed of a group of ultra-fine powder of natural ore material, which is added in the grease (or oil). During the operation of the bearing, the chemical occurs under the thermal energy generated by the friction of the metal on the friction surface. The displacement reaction produces a smooth wear-resistant iron-based silicate wear-resistant protective layer (cermet layer) on the friction surfaces of the rolling elements and raceways, so that the service life of the bearing is greatly increased.