1. Typical faults of vehicle bearings - peeling phenomenon.
After the breakdown of the fault bearing, it is observed that the working surface of the bearing roller is peeled off, while the edge of the roller falls off.The working surface of the inner and outer rings of the bearing also produces metal sheet spalling, and pits also appear on the working surface of the inner and outer rings in contact with the edge of the roller, showing a circular distribution, as shown in Figure 1 and 2.The bearing cage has also been seriously damaged and broken, and there are plane scars on the plane of the cage.
2. Cause analysis of bearing failure
For the analysis of bearing damage characteristics, the basic reasons for bearing failure are mainly as follows:
1) Contact fatigue damage.
2) The bearing has been subjected to abnormal load such as high contact load or impact load, such as hot metal truck in desulfurization or lifting tank operation, is subjected to large impact load;Or the hot metal truck in the heavy tank through the bend, by the role of too high contact load.
3) Improper assembly of bearings or too small clearance leads to excessive additional contact stress between components.
4) Poor lubrication. Due to the poor maintenance environment of metallurgical enterprises, foreign bodies such as iron slag, cotton yarn and dust are mixed into the lubricant during bearing maintenance.
3. Measures to improve the quality of bearing testing
1) Choose bearing clearance properly
Clearance is an important factor for the normal operation of rolling bearings, which can be divided into axial clearance and radial clearance.Choose the appropriate clearance, can make the load between the bearing rolling body reasonable distribution, can limit the shaft (or shell) axial and radial displacement, to ensure the rotation accuracy of the shaft;Can make the bearing work normally at the specified temperature;Reducing vibration and noise is conducive to improving the life of bearings.Therefore, when choosing bearings, appropriate bearing clearance must be selected.The selection of bearing clearance should consider the working conditions of the bearing, such as load, temperature, speed, etc.
2) improve the assembly quality of bearings
(1) selection and measurement link: in the assembly of bearings, making the correct selection is an important factor to ensure the reasonable clearance of bearings. But the current measurement means and tools are very single, and can not be accurately selected for bearings, so it is recommended to buy the more advanced measuring tools at present;After the assembly of bearings, the process of clearance measurement is still needed. However, due to the limitations of tools and measurement technology, this procedure has not been implemented yet. It is suggested to add this procedure.
② Operation inspection link: after the bearing is installed, it should be checked to ensure that the bearing is installed in place, rotating flexible and without jacking. If the bearing is installed improperly, it will cause the bearing temperature to rise rapidly and damage, or even major accidents such as the bearing jacking and fracture.It is recommended to add bearing running and inspection procedures.
3) Improve bearing maintenance and storage environment
① maintenance environment: due to the particularity of the maintenance environment of metallurgical enterprises, there are a lot of iron dust and dust in the maintenance environment, so when the bearing is overhauling, it is necessary to keep the surrounding environment clean, and do not stick to hand sweat and dirt.
② Storage environment: bearings shall not be stored directly on the ground (need to be above 30cm from the ground), avoid direct light and cold walls.In order to prevent rust, store in the temperature of about 20℃, humidity below 65% environment.Bearings placed in acidic air are easy to rust and discolor, so we should strengthen the storage management of bearings to ensure that new bearings are not damaged by external factors.
4) standardization of axle box disassembly and assembly
At present, a more extensive bearing repair work, especially in the axle box found in the process of dismantling, sometimes using hammer percussion, this might cause bearing internal damage, shorten the working life of the bearing, so the bearing maintenance management at the same time, to a positive deep line information, to find problems, effectively improved, and develop the corresponding maintenance tools, improve the quality of bearing repair.
5) eliminate the loading of inferior bearings at the source
(1) outer packaging inspection: under normal circumstances, the factory brand has its own special designers for external packaging design, and arrange production conditions pass the factory production, therefore, packaging from lines to color blocks are very clear.
(2) steel seal word inspection: usually printed on the bearing body brand words, label, etc., the font is very small.But is produced mostly using steel technology, and in the heat treatment before the word, so although small font, but concave deep, very clear.And fake products font not only fuzzy, and printing technology rough, font floating on the surface, can even be easily wiped out by hand.
(3) Rotation check: the left hand holds the bearing body cover, the right hand toggle the coat to rotate it, listen to whether there is noise.Because the production conditions of most counterfeit products are backward, and even completely manual workshop operation, it is inevitable that sand and other sundry things will be mixed in the production process and hidden in the bearing body, so there will be noise when rotating.This is the biggest difference between the factory brand which strictly implements the production standard and operates by machine.
Surface quality inspection (4) : due to the current domestic antirust technology is not particularly pass, so the antirust processing was carried out on the bearing body and is easy to leave the thick oil stains, glue holding the thick thick, and imported from abroad can hardly see the trace of rust-proof oil bearing, special care experts say imported bearing smell a smell, rust-proof oil is certainly exist, just can't see.