What occurs when a sliding bearing works is sliding friction; the size of the sliding friction force mainly depends on the manufacturing accuracy; and the size of the sliding bearing friction force mainly depends on the material of the bearing sliding surface. Sliding bearings generally have self-lubricating working surfaces; sliding bearings are divided into non-metal sliding bearings and metal sliding bearings according to materials.
Non-metallic sliding bearings are mainly plastic bearings. Plastic bearings are generally made of engineering plastics with better performance. More professional manufacturers generally have self-lubricating modification technology of engineering plastics. They use fibers, special lubricants, glass beads, etc. to enhance the self-lubricating modification of engineering plastics to achieve a certain performance. The modified plastics are then processed into self-lubricating plastic bearings through injection molding.
The most commonly used metal sliding bearings at the beginning of the 21st century are three-layer composite bearings. This type of bearing is generally based on a carbon steel plate. A layer of spherical copper powder is first sintered on the steel plate through sintering technology, and then a layer of PTFE lubricant of about 0.03mm is sintered on the copper powder layer. The main function of the middle layer of spherical copper powder is to enhance the bonding strength between the steel plate and PTFE. Of course, it also plays a certain role in carrying and lubricating during work.
There are many types of sliding bearings:
① According to the direction in which the load can be carried, it can be divided into two categories: radial (radial) sliding bearings and thrust (axial) sliding bearings.
② According to the type of lubricant, it can be divided into oil lubricated bearings, grease lubricated bearings, water lubricated bearings, gas bearings, solid lubricated bearings, magnetic fluid bearings and electromagnetic bearings 7.
③According to the thickness of the lubricating film, it can be divided into two categories: thin film lubricated bearings and thick film lubricated bearings.
④ According to the bearing material, it can be divided into bronze bearings, cast iron bearings, plastic bearings, gemstone bearings, powder metallurgy bearings, self-lubricating bearings and oil-impregnated bearings.
⑤ According to the bearing structure, it can be divided into round bearings, elliptical bearings, three-oil blade bearings, stepped surface bearings, tilting pad bearings and foil bearings.
Bearings are divided into split and integral structures. In order to improve the friction properties of the bearing surface, one or two layers of anti-friction material are often cast on the inner diameter surface, which is usually called a bearing lining. Therefore, there are bimetallic bearings and trimetallic bearings.
The bearing bush or bearing lining is an important part of the sliding bearing. The materials of the bearing bush and bearing lining are collectively called bearing materials. Since the bearing bush or bearing bushing is in direct contact with the journal, the journal part is generally more wear-resistant, so the main failure form of the bearing bush is wear.
The wear of the bearing bush is directly related to the material of the journal, the material of the bearing bush itself, the lubricant and the lubrication state. These factors should be comprehensively considered when selecting the bearing bush material to improve the service life and working performance of the sliding bearing.
Commonly used sliding bearing materials include bearing alloy (also called Babbitt or white alloy), wear-resistant cast iron, copper-based and aluminum-based alloys, powder metallurgy materials, plastics, rubber, hardwood and carbon-graphite, polytetrafluoroethylene (Teflon, PTFE), modified polyoxymethylene (POM), etc.
Sliding bearings absorb and transmit the force between relatively moving parts and maintain the position and positioning accuracy of the two parts. In addition, directional motion must be converted into rotational motion (such as a reciprocating piston engine).
Sliding bearings are in surface contact, so a certain oil film must be maintained between the contact surfaces. Therefore, the following issues should be paid attention to when designing:
1. Make sure that the oil film can smoothly enter the friction surface.
2, oil should enter the bearing from the non-loading surface area.
3. Do not make the full-ring oil groove open in the middle of the bearing.
4, such as oil tiles, with oil grooves at the joints.
5, the oil ring must be fully reliably supplied with oil.
6. Do not block the oil filling hole.
7, Do not create a stagnant oil flow zone.
8, prevent sharp edges and corners that cut off the oil film.
Source: Fair Detection
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