Wide temperature self-lubricating bearings, solid lubricant content sufficient to release even with good self-lubricating properties and seizure resistance, can effectively protect the journal achieve lasting purpose. Suitable for high-temperature, low-speed, heavy, dusty, run under water shower and there is shock and vibration environments, and can be widely used in mining machinery, metallurgy, petroleum, chemical, food, textile, paper, printing and dyeing machinery and equipment rolling and plain bearing parts.
Casting machine bearing temperature and water vapor is in the environment, many bearing grease, grease add a relatively short time because of the high temperature and melt overflow removed, maintenance difficulties, equipment surfaces health is also difficulty swabbing. Further steel bearings in hot, wet tide solid lubricating bearings easily rust corrosion environment, the failure rate is very high, higher equipment maintenance costs, equipment operation subject to the following two problems often troubled.
Fueling operation is difficult to achieve a high temperature continuous operation pulling ingot casting machine, shift spindles, then the spindle, turned spindles and other devices are installed in the unit housing design regularly inject grease nipple facilities on each rotation of the bearing, must stop when oiling housing demolition, oil grease gun pressure on people. And the whole point oiling up to 30 multiple, long-term operation and maintenance can not achieve this cumbersome oiling operation, had a handheld shower pouring dilute oiler in the operation of external bearing sleeve, lubricating oil is difficult to enter the bearing friction between large portion of the bearing in the frictional state.
High ambient temperature, grease molybdenum disulfide grease suited to the current Rolling casting machine used is considered to high temperature grease, we know it is based on oil are petroleum products, plus a small amount of high temperature molybdenum disulfide additive, its temperature limit i.e. 120 ℃. According to the measuring caster bearing operating temperature up to 200 ℃, far beyond the grease temperature limit.
In such high temperature conditions, the grease base oil becomes thinner and gradually evaporated, leaving carbon residue, molybdenum disulfide, dust mixed into a solid block in the rolling bearing holder solidified, not only lose its lubricating effect, also impede the normal operation of the rolling bearing and wear out quickly, up to two weeks would have shut down, remove the bearing grease clean ones.
First, the wear condition
Abnormal wear of bearing ingot casting equipment bearing running two problems are caused by more serious. Taking a aluminum ingots companies pull mechanism, for example, bearing an average life of 2 months, severe wear of the inner virtues 5MM worn, causing the device can not continue to run.
Wear is uneven. The reason is that the original design for the oil can not be achieved, bearing exterior had to run the shower burning light oil, pour a small amount can burn the bearing, the wear on the smaller, can also be seen from the table, more than 50% of the shaft and sleeve no lubricated, but is generating strong adhesive wear under dry friction condition. This increases the shaft and swim wear out quickly set the gap, the dust more accessible, creating a vicious cycle.
Second, oil-free self-lubricating bearings selection
Machinery and equipment in order to solve the high-temperature, low-speed, heavy, dusty, water shower and there is shock and vibration lubrication problem, use oil-free self-lubricating bearings.
1, the bearing structure of self-lubricating bearings are arranged in order to develop the friction surface of the metal substrate bearing the appropriate size cavities, and embedded into the composite of molybdenum disulfide, graphite or the like embedded in the block self-lubricating metal sleeve, made of composite bearing, solid lubricant friction area of 25-65%. Solid self-lubricating block can work at a high temperature of 280 ℃. However, due to its low mechanical strength, carrying capacity is weak, easily deformed, it will be able to insert in the metal hole bath suppress this disadvantage, forms part of the role played bearing metal, self-lubricating block lubricant.
This self-lubricating bearing lubrication mechanism of sliding friction in the shaft and sleeve of the process, since part of the lubricating material molecule is transferred to the metal surface of the shaft, filling the small, uneven surface and form a layer of relatively stable solid lubricant film , causing wear between solid lubrication film to prevent adhesion of the shaft and sleeve wear. This is a reasonable combination of a combination of copper alloys and non-metallic materials by grinding their complementary advantages, especially for oil-free, high-temperature, high-load, low-speed, anti-fouling, corrosion, strong radiation environment movement amplitude, and Use the following in water or other solution infiltration can not add grease special working conditions.
2, self-lubricating block area accounted for more than self-lubricating block accounted for much of the running speed of the surface area of the relevant bearing strength, low operating speed; large bearing strength, metal occupied area should be larger. The grab ingot Trolley line axle Chengzi Run slider occupied area is about 25%, pull starter mechanism shaft bearing lubrication to the full, has little bearing strength, self-lubricating block occupies an area of about 65%.
3, on the technical requirements of the liner material should be used in an alloy of copper bush, bush have a high hardness, are generally required to heat treatment, the hardness is not less than HRC45.
4, self-lubricating block geometry and inlaid requirements. Self-lubricating block has a cylindrical shape and rectangular two, self-lubricating can be cylindrical in accordance with the size of the area occupied, on the contrary can be rectangular. Whatever the shape of the mosaic firm must prevent the loss in operation.
5, with the gap between the bush and the axis of linear expansion coefficient values of self-lubricating block about 10 times stronger than steel. To meet the bearing temperature changes from the original gap between the shaft and the bushing metal parts moving with four (D4 / DC4) 0.032 ~ 0.15MM, increased to 0.45 ~ 0.5MM. Self-lubricating block in friction side protruding metal bushing 0.2 ~ 0.4MM. This will be fully lubricated bearings running in the initial run-in period, reducing the power consumption of the drag power.
6, oil-free self-lubricating bearings advantage
A, non-oil lubrication oil lubrication or less, apply to the oil or fuel is difficult to place, it can be used without maintenance or less maintenance;
B, good wear resistance, low friction, long life;
C, there is the right amount of plasticity, can stress distribution in a wide contact surface, increase the carrying capacity of the bearing;
D, static and dynamic friction coefficients are similar, can eliminate crawling at low speed, thus ensuring the accuracy of machine operation;
E, make the machinery to reduce vibration, reduce noise, prevent pollution and improve working conditions;
F, during operation, can form a lubricating film, played the role of protecting the shaft, no bite-axis phenomenon;
G, for a low hardness grinding axes, without conditioning the shaft can be used, thereby reducing processing difficulty related parts;
H, thin-walled structure, light weight, can reduce mechanical volume;
I, bushing made of brass can be used in corrosive media.
Through practice, casting machine bearing to oil-free self-lubricating bearings, has been used continuously for 15 months, and is still running, shafts, bushings gap generally not exceed 1MM, it is also expected to re-use 12 months, significantly more than the original life (two months).
Oil-free self-lubricating bearings can only get better used in the aluminum ingot casting machine, but can be adapted to oil-free, high-temperature, high-load, low-speed, anti-fouling, corrosion, strong radiation environment movement amplitude, as well as in the water equipment or other solution infiltration under impossible lubricating grease special working conditions, such bearings have a wider promotional value.
Currently used in various mechanical industries most or ball bearings, needle roller and the like, but a small part of the self-lubricating bearings have been used, we believe that in the near future from the lubricated bearings will become the dominant bearing. Here are some application features and advantages of self-lubricating bearings:
1, no oil lubrication oil lubrication or less, apply to the oil or fuel is difficult to place, it can be used without maintenance or less maintenance;
2, wear resistance, low coefficient of friction, long life;
3, there is the right amount of plasticity, can stress distribution in a wide contact surface, increase the carrying capacity of the bearing;
4, static and dynamic friction coefficients are similar, you can eliminate crawling at low speed, thus ensuring the accuracy of machine operation;
5, make the machinery to reduce vibration, reduce noise, prevent pollution and improve working conditions;
6, during operation, can form a lubricating film, played the role of protecting the shaft, no bite-axis phenomenon;
7, for a low hardness grinding axes, without quenching axis can be used, thereby reducing processing difficulty related parts;
8, thin-walled structure, light weight, can reduce mechanical volume;
9, a variety of metal plated steel back can be used in corrosive media; has been widely used in various mechanical sliding parts, such as: printing presses, textile machines, tobacco machines, micro-motors, automobiles, motorcycles and forestry machinery and many more.