The introduction of sliding bearing failure cause - bearing knowledge

Imported bearing in the use and purchase always run into some technical issues, today by tianjin jia rui sheng industry bearing co. , LTD. Technical staff to explain to the cause of sliding bearing failure is introduced. 1. Materials and blank manufacturing factors ( 1) Lining and backing with bad this is casting tin or lead base bearing alloy lining layer of the sliding bearing of the main problems. Good can strengthen the combination of tin and lead base bearing alloy and help heat dissipation on the surface of the bearing. To combine good, before casting tin and lead base bearing alloy must be hung on the backing in combination with tin, strictly control the temperature of the backing and bearing alloy. When bearing shell size allowed, hang tin tin bath, liquid of pure tin bath should be kept in 280 ~ 300 ℃, the tin solder bath liquid temperature should be kept in 270 ~ 300 ℃, the bearing shell submerged in liquid, liquid when the bearing temperature reaches can be removed. Large bearing shell can be used to cross hanging tin tin method, first the bearing shell with flame heating, then the pure tin or solder coating on the surface of tin to hang on. Practice has proved that the backing casting not only to the surface of the lining to make slot wedge backing with the combination of lining and cutting groove shoulder Angle, the stress concentration will lead to crack. ( 2) Stomatal large base bearing alloy with tin or lead lining shell, inadequate pouring temperature too low or backing preheating, backing on the lining combining will appear on the surface of bubbles. The bubbles is bad for heat dissipation on the surface of the bearing shell, also can weaken the tin or lead lining base bearing alloy. Cast copper alloy casting, because the hydrogen in the copper alloy is released, will cause osteoporosis. ( 3) Coarse grains is this tin and lead base bearing alloy lining bearing characteristic of the problem. In the process of cooling solidification of casting bearing metal, if the cooling speed is slow, antimony, tin grain size will be more than 0. 1 mm, the naked eye can be observed. Such intermetallic compounds are easily broken, after fracture from the friction surface, become the particles into the oil circulation system, bearing damage. ( 4) Lead uneven distribution of cu and pb eutectic, therefore bearing use of copper base bearing alloy copper lead, lead distribution uneven phenomenon may occur. After casting copper lead alloy rapid cooling can prevent lead distribution is uneven. Use the method of powder metallurgy manufacture copper lead bearing shell, can thoroughly solve the problem of uneven distribution of lead in copper lead alloy. 2. Installation and operation factors, 1) On the bad shaft bearing at least need two fulcrum, if two sliding bearing on the bad, alignment error is large, the load on the bearing shell width will be uneven, the distribution of oil film instability, edge contact occurs in adhesive wear. ( 2) Bearing and the bearing hole with improper bearing and the bearing hole with improper, loose bearing bush may lead to fretting wear. Cooperate with loose or micro wear, adverse to the heat transfer, may make bearing friction surface temperature is too high. Bearing and bearing fitting surface is not clean, there are particles and dirt, will also make the bad conduction. In a word, check the damaged bearing surface, bearing bashes is likely to provide important information, so should be more careful can't forget to check on the back of the bearing. ( 3) Particle invasion particle invasion is one of the important reasons, sliding bearing failure into sliding bearing particles outside, also have come from the inside of the bearing, is a product of the bearing wear itself. External particles mainly through the bearing clearance to enter and by the lubricating oil into, therefore, sliding bearing running environment of clean degree and the sealing structure is very important. Lubricating oil can play the role of clean, also can bring particles into the bearing clearance, the key lies in its filtering, so the selection of filter, the use and maintenance is extremely important. Usually bearing shell material has a certain ability of hidden particles embedded sedimentary particles than embed hiding ability of bearing material, the bearing friction surface will be grinding, scratches and wear, gap increases, the surface is rough. Based on bearing work environment, make the lubrication method, match the filter accuracy, seal and bearing shell material, is sliding bearing designers must concern. Only the composition of the embedded bearing shell particles, to know their origin and established period and the best way to eliminate them. Using chemical separation technology can be isolated from the bearing surface embedded particles. For example: layer of electrodeposition of lead have been bearing shell, can use a mixture of acetic acid and hydrogen peroxide separation; Aluminum tin alloy bearing shell can use sodium hydroxide separation; Tin antimony bearing alloy can be used a mixture of acetic acid, hydrogen peroxide and sodium hydroxide. ( 4) Corrosion of lubricating oil in the process of using oxidation, oxidation product is acid, they have a corrosion effect on bearing materials. In addition, there are some special attention must be paid to the corrosion forms, such as: oxygen antimony in tin bearing alloy corrosion, sulfur corrosion of silver and copper shell materials and moisture content on the corrosion of copper lead alloy, etc. ( 5) If enough lubricating oil and the viscosity change of sliding bearing lubricating oil quantity shortage will cause catastrophic accidents. Dynamic pressure bearing, especially in the dynamic pressure bearing heavy equipment out of many, often due to a lack of lubricating oil in the startup and result in bearing damage, so when the boot device, make the oil circulation in advance to provide lubrication is very important. Hydrostatic bearing the main advantage is can start on the lubricating oil film, so the design using hydrostatic bearing equipment, must make the pledge that we can start the hydrostatic bearing system, after the boot device. In the engine, especially in engine cold light load operation and operation, often mixed with fuel oil. After the fuel into the lubricating oil viscosity decreased, reduced to a critical value, the bearing will be in early fatigue damage, drop too low, also disastrous accidents will happen.