Rolling bearings and sliding bearings

Rolling bearings and sliding bearings

The bearings used for rotational motion are designed as rolling bearings or sliding bearings. There is a difference in whether the force generated between parts that can move relative to each other is transmitted through rolling or sliding elements.

Rolling bearings

Rolling bearings generally consist of two bearing rings with complete raceways. The rolling element is installed between the rings and rolls on the raceway. Rolling components can be ball, cylindrical rollers, needle rollers, tapered rollers, or barrel rollers. Rolling components are generally guided by a cage to maintain a uniform distance between them and prevent contact with each other. In needle roller bearings and ribbed self-aligning roller bearings, the cage also ensures the correct position of the rolling components. When the bearing can be disassembled, the cage gathers the rolling components together and makes the installation of the bearing easier. For special applications, rolling bearings with fully compensated soccer balls can use cylindrical rollers or needle rollers.

Steel is the standard material for metal sheet cages, and some applications also use brass. The fixed holder is made of brass, steel, laminated fabric, and other materials. Thermally flexible material retainers are also widely used, especially nylon retainers reinforced with fiberglass.

The bearing rings and rolling components are mainly made of quenched chromium steel, although cage quenched steel is also used. Special bearings designed for extreme operating conditions such as load, speed, temperature, and corrosion are made of steel, plastic, ceramic, or other materials that are resistant to temperature and/or corrosion.

Rolling bearings can be open versions or with one or both ends sealed. The most common types of seals are gap seals and lip seals.

The characteristic is the application

The characteristic of each roller bearing design is to make it particularly suitable for specific bearing applications. It is impossible to establish universally effective rules for the selection of bearing types, as several factors usually need to be considered and weighed. In addition to load and speed, attention should also be paid to the effects of temperature, lubrication, vibration, installation, maintenance, etc. In many cases, at least one of the main dimensions of a bearing - usually the diameter of the borehole - has already been determined by adjacent structures.

Rolling bearings mainly used for radial loads are described as radial bearings. Most radial bearings can support composite loads, such as deep groove ball bearings, angular contact ball bearings, tapered roller bearings, or self-aligning roller bearings. Cylindrical roller bearing N, NU， Most needle roller bearings, stamped outer ring needle roller bearings, and needle roller bearings and cage components can only support radial loads.

Rolling bearings mainly used for axial loads are described as axial bearings. Axial self-aligning roller bearings and unidirectional axial angular contact can support composite axial and radial loads. Other models of axial bearings are only suitable for axial loads.

If there is a small amount of radial space, bearings with low cross-sectional height must be selected, such as needle rollers and cage components; Specific series of needle roller bearings with or without inner rings, deep groove ball bearings, and self-aligning roller bearings.

If there is a small amount of axial space, bearing series including single row cylindrical roller bearings, deep groove ball bearings, or angular contact ball bearings are suitable for radial and composite loads. For axial loads, use axial needle roller and cage components, axial needle roller bearings, or axial deep groove ball bearings.

Another characteristic is how bearings guide the shaft. There are bearings that allow axial displacement, bearings that guide one shaft in one or two axial directions, bearings that allow angle adjustment, and bearings that allow adjacent structures to be eccentric

The size of bearings is mainly determined by the size and type of load - dynamic or static - bearing load capacity and the requirements for service life and bearing configuration reliability. Rotating bearings are subjected to dynamic stress. If there is only very slow relative motion between the bearing rings, and if rotational motion occurs or a load is generated in a stable state, the bearing will bear static load. If the external dimensions are consistent, roller bearings can generally withstand higher loads than ball bearings. Ball bearings are typically used for small or medium loads, while roller bearings are often used for higher loads and larger shaft diameters.

Sliding bearings

The function of sliding bearing configuration, like rolling bearing configuration, is to support the components that move between each other through guidance. They must support and transmit the force generated in this situation. By using rolling elements, the bearing configuration elements in the rolling bearing configuration are separated from each other - rolling elements - active components in the sliding bearing configuration - usually shafts, columns, or strip steel - slide on the sliding surface of static bearing pads, bearing outer rings, or sliding bars. Directly generate sliding motion between the sliding layer of the bearing body and the manufactured components. Ensure lubrication through deep lubrication or a solid layer for a carrier. In radial motion, the gap between the shaft and the sliding layer ensures the mobility of the sliding partner.

Sliding bearings can be used as radial bearings, axial bearings, strip steel, outer rings, and many other designs. They run quietly and are particularly suitable for use in positions that support high loads under relatively slow rotation, as well as for rotational motion and high/low temperature environments. Due to their universal characteristics, they are almost used in all industrial fields, especially in places where the available bearing configuration space is limited.