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Application of metal self-correcting data on bearings
Source: China Bearing Network Time: 2018-04-02
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First, the quality of the types of bearing products in China:
From 1997 to 1999; according to the "National Supervision and Inspection Product Catalogue" prepared by the State Bureau of Quality and Technical Supervision, the product quality inspection of the rolling bearing; the three-year uniform pass rate was 68%. The quality of the inspection product in 2000 was 6 higher than that in 1999. Percentage; proof of quality supervision and inspection management operations have achieved significant effects. Compared with the developed countries of the bearing industry; the distance between domestically produced bearings in terms of type and quality is the most important:
1. There are few domestically produced bearings; the output is low. The bearing industry produces a total of 150,000 bearing types; the number of bearings produced in China is only 20,000; and most of them are general-purpose products. There are more than 2,000 domestic bearing companies; The sum of the output is listed after the international five major bearing companies (SKF, NSK, KOYO, NTN, NMB); thus; the size of China's bearing company. The stalls are swaying at night.
2, the domestic bearing scale accuracy public service dispersion is large. Although China's bearings in the scale of public service and rotation accuracy has made great progress; near the level of foreign brand-name products; but there is still a large gap in the scale error distance.
3. In terms of oscillation, noise and abnormal sound; the oscillating extreme value of China's bearings is higher than that of foreign famous brand products by more than 10dB. Taking 6202 bearing as an example; foreign famous brand products are about 26dB; sampling domestic products of 18 bearing companies; It is 37. 5dB.
4. The lifespan and reliability of domestic bearings are still low. Take the deep groove bearing as an example; the life of foreign famous brand products is usually more than 8 times the calculated life (up to 30 times); the reliability is up to 0. 98. Above, the life expectancy of domestic bearings is usually 3 to 5 times the calculated life; the reliability is about 0.96.
Because the domestic bearings have the above-mentioned distance in terms of type and quality; as a bearing producing country; China's increasingly developed home appliances, automobiles, textiles, machine tools and other occupations have to import many bearings every year. The imported bearing products are mainly low in household appliances. Noise and silent ball bearings, longevity number of automotive bearings, machine tool spindle bearings, high-speed railway passenger car and truck bearings, high-speed textile machinery bearings, etc. Imported 640 million sets in 1999; imported 930 million sets in 2000; imported 7 in 2001 200 million sets. See Table 1.
Imported bearing statistics from abroad (Table 1)
Bearing type 1999 2000 2001 Number of fields used (10,000 sets) Value (ten thousand US dollars) Quantity (10,000 sets) Value (ten thousand US dollars) Quantity (10,000 sets) Value (10,000 sets) Value (US$ 10,000)
Ball bearing 329471436442277201494995624016 Home appliance, machine tool textile tapered roller bearing 211480846826215957 Automotive spherical roller bearing 243473211337362397 Mining, petroleum mechanical needle roller bearing 557721156979918251011 Automobile, textile machinery cylindrical roller bearing 3418175610807223386104054 Machine tool, rolling mill other rolling bearing 266428546370139064182758867 Machine tool bearing bearing 305541235567263475 Textile machinery Calculation 643243462492978445837150748989
Because the life of the domestic bearing is short; the bearing can not be the same as the mechanical and electrical equipment; the protection of the bearing is replaced; the utilization of the equipment is reduced and the repair cost is added. The failure of the bearing is low due to the low reliability of the bearing; The general bearing produced by the bearing industry in developed countries has begun to use the new concept of “infinite lifespanâ€; the special bearing also proposes the “synchronous life†of the supporting mainframe and the “zero failure†target requirement during the overhaul period. Domestic bearings also need to continue to do their best to work hard on the longevity and reliability of the products.
Second, the "metal wear self-correction data" to add bearing life and reliability mechanism:
“Metal wear self-correcting dataâ€; is a set of micron-sized particle data of messy components composed of natural ore materials such as magnesium hydroxysilicate [Mg6(Si4O10)(OH)8]. The first is taken from natural ore data. These compositions do not dissolve in smooth fat; do not smooth chemical attack; do not change the viscosity and other physical and chemical properties of the oil; have no toxic side effects; the chemical properties at normal temperature are very stable. When smooth grease is used as a carrier, these particles When the data is brought into the bearing assembly; these particle data in the bearing transformation on the bearing runway and rollover superfine grinding effect; a series of physical and chemical changes; the metal microscopic layout of the conflicting appearance.
The physical change of the particle data in the appearance of the metal conflict is: the rolling body is tumbling in the raceway; under the action of the conflicting force; the ultrafine particle particles are further crushed; at this moment, the fine particles have superfine grinding effect on the metal conflict appearance; The ultra-fine grinding action of the particles satisfying the hardness forms the metal surface micro-protrusion cracking; the smoothness of the bearing conflict appearance is further advanced.
The chemical change of the particle data in the appearance of metal conflict is: in super-fine grinding; the flashing temperature of the micro-protrusion cracking causes the displacement of the magnesium atom in the particle crystal and the conflicting iron atom; the appearance of the iron-based metal conflict Iron-based silicate layer; also known as cermet layer. This iron-based silicate layer is attacked when the metal surface micro-protrusion cracks and exhibits flashing temperature; no conflict heat occurs on non-wearing parts; The chemical substitution reaction occurs. Therefore, the formation of the iron-based silicate layer is selective; it will only form a wear-resistant layer on the metal conflict surface of the bearing's roll body and the runway. The bearing will continue to attack during the transition. Wear and tear; the micro-convex cracking and the release heat of the onset of wear can continue the chemical reversal reaction. When the surface is formed with a layer of metal porcelain, the appearance of the surface is advanced, the coefficient of conflict is decreased, and the heat energy of the friction is decreased; The chemical substitution reaction will also be aborted. However, when the wear-resistant protective layer is damaged; the conflict heat of the metal appearance is sharply added; the new replacement reaction will start again; Complex.
Visually visible; the cermet coating on the bearing raceway and the tumbling body is black and shiny; it has a pale blue metallic luster.
It has been determined that this wear-resistant coating has excellent mechanical and physical functions:
Conflict coefficient μ: 0. 003 ~ 0. 007
Microhardness Hv: 1x forward roughness: 14 grade expansion coefficient: 13.6~14. 2 (same as steel)
High temperature resistance: 1575 ° C ~ 1600 ° C
Corrosion resistance: excellent; after adding a small amount of “metal wear self-correction data†to the bearing smooth grease; the service life of the bearing can be greatly extended; the bearing reliability level is also advanced accordingly, and because the bearing conflict coefficient decreases Can save a lot of power energy consumption.
Third, the use of "metal wear self-correction data" bearing life test conditions:
The national bearing quality supervision and inspection was entrusted by the Economic and Trade Commission of the Harbin Municipal Government; the life test was carried out on the 6205 bearing using the “metal wear self-correcting dataâ€. The 24 sets of bearings for inspection were all met to meet the requirements of the first-class products. 3 times extra life test; from then on, 8 sets of bearings were randomly selected to carry out 5 times extra life test to meet the requirements of superior product specifications; then 4 sets of bearings were randomly selected for complete life test.
The experimental report gives the conclusion that:
1. The bearing with 21 times extra life test basically adheres to the rotation precision before the experiment. When the test reaches 3 times extra life; the rotation precision decreases, and the test reaches 5 times extra life; the rotation precision recovers to the original value. .
2. The radial clearance of the bearing to 21 times extra life is slightly different from the radial clearance before the experiment. When the test is to 3 times the extra life, the clearance is evenly reduced by 2.5 μm. When the extra life is 5 times; the clearance is evenly increased by 3μm (basically recovered to the pre-experimental value). Continued addition with the experimental time; the radial clearance of the bearing is sometimes added and sometimes reduced; the amount of change is small. Try to 21 times extra life Time; also recovered to the pre-test value.
3, when the bearing is tested to 21 times extra life; the bearing ring raceway and the steel ball are black and shiny; there is no wear at all.
4, "metal wear self-correction data" used in bearings; can extend the life of the bearing.
In the process of bearing life test, the following conditions were presented: when the experiment was carried out to 8 times extra life; the bearing inner ring raceway numbered SM21-024 failed due to the abrasive grinding of the grinding wheel at the time of production. The experimental report pointed out that the bearings with grinding burns in the bearing raceway usually have a life expectancy test; less than 1 times the extra life of the raceway will fall off and fail. The bearing experiment has reached 8 times extra life; this is obviously It is the "metal wear self-correction data" to play the role of extending the life of the bearing.
In the process of bearing life test; there were three times of attack on the nylon frame to melt and flow out; but the bearing replaced the new nylon after the frame is still sustainable. The reason is: the smooth grease application temperature is 80 ° C; in the bearing life test In the middle of the bearing, the temperature rises and the smooth grease is lost. Under the dry conflict, the bearing temperature is further increased to exceed 254 ° C; then the nylon holder is melted and flows out. In the past, when the situation occurs; the steel ball and the ferrule It will anneal and bond together; make the bearing invalid. But in this experiment, the bearing ring and the steel ball are intact; the generated cermet layer plays a role; the dry conflict coefficient is reduced; the heat of the dry conflict is lacking To anneal and bond steel balls and ferrules.
For details, please refer to the National Bearing Quality Supervision and Inspection Center: “Experimental Report on Metal Wear Self-corrected Bearing Life†(February 2003).
Subject to experimental funding; 6205 bearing life test was carried out to 21 times the extra life and stopped.
Fourth, the use of the "metal wear self-correction data" process of the production and use of bearings:
Since the last year, Harbin Aite Bearing Co., Ltd. has carried out metal wear self-correcting data processing for the new bearing produced; it has achieved remarkable results.
1. High-speed motor spindle bearing The high-speed motor spindle bearing is processed by the metal wear self-correcting data process; the limit speed is advanced; the grease can be used even at the speed of dn≤1×106 rpm.
Under normal conditions, when the bearing speed dn ≥ 0. 4 × 106 rev / min; it is necessary to use oil mist smooth. The oil supply equipment needs air compressor, oil circuit and high-grade stator oil; sprayed inside the bearing under high-pressure air carrying Oil. Oil and gas are injected from one end of the bearing; ejected from the other end; the escaped oil mist floats in the air to form air pollution; the fuel consumption is increased; the air compressor uses a large amount of electricity; the noise is also large. Bearings after self-correcting data disposal; smoothing of grease instead of oil mist; completely disposing of the effect of helium gas with smooth oil mist; reducing the mechanical processing of oil supply; saving the production cost of the product. The service life is usually 2 months; the bearing treated by the metal wear self-correcting data process; the application of grease smoothness can be used for up to 1 year.
2. CNC machine tool spindle bearing CNC machine tool spindle bearing double and quadrilateral contact ball bearing; the bearing is treated by metal wear self-correcting data process; its accuracy, temperature rise, noise, stiffness and "SKF" in installed operation "The company's similar products are no different. The machine has been in operation for more than a year; its function remains unchanged.
3. Oilfield heavy oil pump bearing oilfield heavy oil booster pump bearing consists of deep groove ball bearing, cylindrical roller bearing and thrust ball bearing; the working medium is thick crude oil; the service life of the pump usually does not exceed 3 months. The operation is about 1 week; the pump efficiency starts to decrease; the pump efficiency decreases by 70% in 3 months; the noise is also large; the repair needs to be stopped. The bearing is treated by metal wear self-correcting data process; the noise of the whole machine is reduced from 97dB to 80dB; No abnormal sound; pump efficiency from 53M3 / h to 63M3 / h; motor output power decreased by 17%. Has been operating for 2 months; still adhere to the same conditions.
4, rolling mill roller bearing The bearing accepts heavier load; the price of each set of large bearings is about 1000~2500 yuan; the bearing life is shorter; usually 15~20 working days; the repair cost is higher. With metal wear After the correction of the data process to dispose of the bearing; the number of life advances more than 5 times; greatly reduced the cost of repair.
5. The linear speed of the roller guide roller bearing roller bearing roller bearing roller bearing is 120 m / s; the guiding wheel rotation speed is 15000 rpm; the bearing life is only 8 hours. The bearing after metal wear self-correcting data processing is used; The lifespan reached 40 hours.
6, no force blind zone bicycle shaft bearing This bicycle is an athlete-specific racing car. Because of the layout constraints; to ensure the bearing life; the diameter of the shaft can not be increased; in the application; often attack the shaft cracking event. After the metal wear is self-correcting data technology; the bearing capacity of the bearing can be greatly advanced; under the condition that the outer diameter of the bearing is constant; the diameter of the central shaft is increased by 3 mm; then the problem of cracking of the central shaft is dealt with. The results of the athletes advanced by 6%.
The use of metal wear self-correcting data processing for bearings; it is a pioneering operation since the previous year; the scale of application is gradually expanding; the effect obtained is encouraging. The above application is only In the meantime, some examples of accurate data were obtained.
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