Publish Time: 2020-08-03 Origin: Site
The four-point bearing is a separable structure, and a single bearing can replace the angular contact ball bearing with front combination or back combination.
Four-point bearings can withstand radial loads and bidirectional axial loads, and can limit the axial displacement in both directions, but occupy less axial space than the current double-row angular contact ball bearings.
Compared with other ball bearings, four-point bearings have a smaller axial clearance and a higher limit speed when the radial clearance is the same.
The four-point bearing is suitable for bearing pure axial load or axial and radial combined load mainly based on axial load. Since it is a double half inner ring, the number of balls loaded increases and it has a larger carrying capacity.
· Four-point bearings bear triple responsibility while saving space
· Important advantage of four-point bearings
· material selection of four-point bearings
Four-point contact ball bearings can easily handle radial loads, thrust loads and moment loads simultaneously, which simplifies the mechanical design because it can handle all three loads simultaneously. They are mainly used for slow to medium speed applications, or applications where oscillating motion dominates.
Because the unique ball geometry can produce twice the contact point, the four-point contact bearing can bear radial, thrust and moment loads individually or in any combination. It has a row of balls with inner and outer rings. The ball grooves are generated from two centers, each radius is slightly larger than the ball radius. The contact angle is usually 35° from the radial centerline, but it can be changed to suit the application.
Four-point contact bearings are particularly effective in applications where the ratio of the diameter of the rotating element to the axial length is high. Most have larger aperture to cross-sectional size ratios: the larger the ratio, the thinner and more flexible the thickness of each seat ring. Thin section bearings range in size from 1" to 40" O, and D's slewing bearing ranges from 4" to 178" O.D.
Figures 1 and 2 show how much space can be saved by replacing two bearings with one four-point contact bearing. The turntable design in Figure 1 has a traditional center pillar that is supported by two bearings. Eliminating the center post (Figure 2) reduces the height and weight of the table and frees up space for other components. Without a pillar, the pillar will not deflect.
Four-point contact ball bearings are usually made of traditional anti-friction bearing materials, but like other bearings, the material decision is ultimately determined by the application. High carbon 52100 alloy and 440C stainless steel are common choices for quenching. When selective hardening is required (for example, when the bearing has integral features such as flanges and gears), options include carburizing or induction hardening. For this, alloys such as 8620, 4340, 4150, and 1552 can be used. All parts can be hardened to Rc 58 to achieve 100% load capacity and longest service life. (At Rc 50, the capacity drops to about 50%, and at Rc 45, the capacity drops to less than 30%.)
Figures 1
Figures 2