Publish Time: 2019-06-27 Origin: Site
With the development of the social industry, more and more mechanical equipment has been put into use, bringing great convenience to people's lives. Four point contact ball bearing is used in various industries due to its unique characteristics, which guarantees production. Its materials are also diverse, meeting the needs of different scenes.
Main points
What is four point contact ball bearing
Common material
Application
The four-point contact ball bearing is a separate type of bearing. It can also be said that it is an angular contact ball bearing that can withstand two-way axial load. The inner and outer ring raceways are peach-shaped cross-sections. When there is no load or pure radial load, the steel ball and the ferrule appear as four-point contact, which is the origin of this name.
When only a pure axial load is applied, the steel ball and the ferrule become two-point contact and can withstand two-way axial loads. Four-point contact ball bearings can also withstand moment loads, as well as single row angular contact ball bearings and double row angular contact ball bearings. Four-point contact ball bearings guarantee normal operation only when two points of contact are formed. Therefore, it is generally suitable for those places where there is a two-point contact under a synthetic load with a pure axial load or a large axial load. The four-point contact ball bearing has a high limit speed and is also suitable for those applications where high speed operation is required.
According to the main criteria of the bearing working ability, the material of the bearing should have certain bearing capacity, embedding, thermal conductivity, low friction coefficient, smooth surface, anti-wear, anti-fatigue and anti-corrosion. No single material can fully satisfy all the requirements, which is why the compromise method is often used in most designs. Briefly introduce the performance and application of several bearing materials.
Bearing alloys are widely used. They are usually available in two types: tin-based bearing alloys and lead-based bearing alloys, which have the characteristics of running fast and can easily make the surface very smooth. They are usually attached to the bearing base of the steel as a bearing liner. Babbitt bearings have good adaptability and are self-adjusting for smaller misaligned or defective shafts. Since the proper amount of dust or foreign matter entering the lubricant can be absorbed by the soft material to prevent the gluing failure of the shaft, the embedding property makes them excellent bearing materials. The journal material can be mild steel, hard steel or cast iron.
Bronze bearings are suitable for low-speed and heavy-duty applications where the shaft and bearing are moderately neutral. They can be made from a variety of alloy compositions to achieve a variety of physical properties.
The bearing capacity of this kind of bearing is higher than that of the bearing alloy, and its adaptability is poor, so it is used in the case where the rigidity of the shaft is good and the neutrality is good.
Cast iron bearing materials are widely used in applications where the requirements are not critical. The hardness of the journal must be higher than the stiffness of the bearing. The working surface should be carefully run with a blend of graphite and oil. It is required that the journal and the bearing must be well centered.
The so-called "self-lubricating" or "porous" bearings can be made by first sintering the metal powder and then immersing it in oil. Bronze of various compositions is widely used on porous bearings with less iron. Due to the self-lubricating properties of porous bearings, it is mainly used in applications where it is difficult or impossible to obtain reliable lubrication when using general lubrication methods.
Pure carbon bearings can achieve satisfactory results in high temperature applications or when conventional lubrication methods cannot be used. Teflon is a very common plastic. The bearing made of it has a very low coefficient of friction and is used in the case of oil-free lubrication, it can work under low speed or intermittent swing and heavy load conditions. Experiments have shown that some combinations of materials work well together, while others do not. Excessive wear and tear will occur in combinations of materials that do not work well together.
Aerial platform vehicles
Aerial work platform vehicles typically employ such a slewing ring and are compact. This type of slewing bearing is also subjected to axial force, radial force and tilting moment, and is widely used in small and medium-sized construction machinery.
Truck crane
Truck cranes are usually using large single row four-point contact ball slewing bearing. This type of slewing bearing can bear larger axial load, radial load and tilting moment, enabling crane to lift heavy loads stably and reliably.
Excavator
Excavator is usually using internal quenched gear single row four-point contact ball slewing bearing. This type of slewing bearing can bear axial load, radial load and tilting moment and can withstand large impact. Rotation is flexible and stable.
It is used to support the mechanical rotating body, reducing the friction coefficient during the movement and ensuring its rotation accuracy. It is an important part of contemporary machinery and is used in so many fields. The person in need can choose the bearing according to the needs.