China Factory Best Four-Point Contact Ball Slewing Bearing

1.Why do high-speed bearings choose the four-point contact ball slewing bearing?

Why do high-speed four point contact ball slewing bearings choose the four-point contact ball structure? Why do high-speed bearings choose the four-point contact ball structure? This article analyzes the reasons one by one, and provides some theoretical and practical basis for selection, design and application.

First of all, select the slewing bearing, which is positioned at a high speed, at least above 30rpm, generally more than 10rpm, and the four-point contact ball bearing structure is preferred. Secondly, because the ball bearing and the raceway are in four-point contact ball slewing bearing, which is a point contact, during the movement of the contact point, when the two circles are theoretically absolutely parallel up and down, the flexibility is far more than that of the crossed roller and the three-row ball structure.

The latter is usually a line contact motion process and can be understood as a surface contact. Again, ball bearings can use PTFE cage and copper cage to increase the speed, 60-120rpm. Of course, due to the structure, noise and vibration will occur at extreme high speeds, usually by grinding the grooves and improving the accuracy to the greatest extent possible to reduce the index.

The structure of the four-point contact ball slewing bearing determines the characteristics of high speed, wear resistance and long life. The structure of the four-point contact ball slewing bearing determines the characteristics of high speed, wear resistance and long life.

Carefully check the channel of the four-point contact  ball slewing bearing, the contact point between the steel ball and the channel, and the inner and outer rings are in contact with two points, so it is called a four-point contact ball bearing. Double-row ball bearings are double-row arc grooves.

For the same reason, they are also called eight-point contact ball bearings. Flexible, not easily subject to various errors, it is flexible, easy to install, easy to maintain, and has the best feedback from use. Therefore, compared with the crossed roller bearing and the three-row ball bearing, the rotational speed can be appropriately increased, and the rotational speed can be as high as 70-120rpm when combined with the PTFE cage.

2.What are the matters needing attention in the installation of slewing bearing?

First of all, compared with other parts, the four-point contact slewing bearing is the core of the rotating part and belongs to the precision product. Therefore, it is necessary to understand the installation precautions of the slewing bearing:
1. After understanding the rotation accuracy of the slewing bearing, first ensure that the installation base is flat. Remember, it is very important, the base is not flat, and the hidden danger is great.

2. Whether the force and eccentric load of the bearing are within the theoretical calculation

3. According to whether the bolts are installed or not, pre-tighten them into 180° one by one.

4. Whether the S soft belt area is in the non-load area, that is, the area where the force is not often or the weakest force, taking the crane as an example, the bearing should be installed in the area where the cantilever direction is vertical

5. After the gear meshing rotates in the forward and reverse directions, no other abnormal noises can be gnawed.

6. There is a slight noise after the new bearing is installed. After fully refueling, the forward and reverse rotation still cannot eliminate the abnormal noise.

7. The positioning size of the bearing

8. The size of the mouth of the bearing

9. The seal of the bearing must not be interfered with by foreign objects, otherwise the sealing strip will be damaged

10. There should be no interference in the position of the dust baffle

What factors will cause the installation of the slewing bearing to be unsmooth or even unable to rotate? Taking the following factors into consideration,

1. Mounting holes. The threaded hole of the mounting hole is not standardized, the threading is not complete, and the threading is defective, so that the bolt cannot be screwed in.

2. The center diameter and chord length of the mounting hole exceed the tolerance too much, such as 3-5mm, so that the bolt cannot be pierced

3. The size of the positioning hole and the step is too large and cannot be matched

4. The bearing after heavy load has a rotating dead center or an ellipse, which causes it to fail to operate normally.

5. The bearing is not in the installation direction of the installation design drawing, resulting in the opposite direction of the taper pin, which has potential safety hazards

6. The installation part interferes, such as tooth top interference, there is a phenomenon of gnawing teeth, and some parts conflict with each other

7. The design of negative clearance is unreasonable, resulting in the phenomenon of inclined force, partial load and clearance after installation

8. The design of the equipment structure is unreasonable, which leads to the failure of normal debugging.