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Spherical roller bearings have two rows of rolling elements, which mainly bear radial load and axial load in either direction. With high radial load capacity, it is especially suitable for working under heavy load or vibration load, and can compensate the concentricity error caused by installation and shaft deformation. It is widely used in various machinery in steel, mining, papermaking, shipping and other industries. In order to meet the working requirements of the bearing under high-speed and heavy load conditions, it is necessary to ensure the reliability of the bearing and prolong the service life of the bearing. How to match the performance of outer ring, inner ring, roller and cage is of great significance, and the design of cage is the key. The design of traditional cage has some shortcomings.
Based on years of experience, this paper discusses the causes and solutions of its formation.
1. Problems in the original design
The traditional design of spherical roller bearing has no problems in its main parameters, outer ring, inner ring and roller design strength and rigidity. Only the cage design has certain defects, mainly in the following aspects:
(1) Due to the angle of the tool top during machining, the bottom of the cage pocket is 150. The process taper thins the wall thickness of the cage bottom, which affects the strength of the cage. The contact area between the roller and the cage bottom is also small. The root of the cage beam is thin and the strength is poor. During the working process of bearing, when bearing impact vibration and heavy load, the cross beam of cage is easy to break from the root, which affects the reliability of bearing.
(2) The cage pocket is a combination of cylinder and round platform, which determines that the contact area between the pocket and the roller is small, which is not conducive to the guide of the cage pocket to the roller. When the bearing bears impact load and rotates at high speed, the axis of individual rollers is prone to large angle lateral rotation. Once the axis of a roller rotates sideways at a large angle relative to the axis of the cage pocket, the rolling of this roller will lag behind the rolling of the normal roller, and the cage beam is prone to fracture; When machining the pocket, the positioning of the drill or boring cutter is not easy to be accurate, and it is not easy to ensure the center diameter and angle of the pocket, which affects the machining accuracy of the cage, and is easy to cause the end face of the cage not perpendicular to the axis of the pocket, which affects the rotation flexibility of the bearing after the sleeve is assembled, and is easy to produce noise and abnormal temperature rise of the bearing. The design of cage before improvement is shown in Figure 1.
Figure 1
2. Improve the design
In view of the defects of the above cage, the design of the cage is improved from three aspects. The improved design is shown in Figure 2.
Figure 2
(1) The cage pocket has changed from the traditional cone and cylinder structure to the ball and cylinder combined structure, that is, the contact state between the roller and the cage pocket has been changed from the original line contact to the improved surface contact, and the package capacity of the pocket to the roller has been increased. The calculation formula is as follows
Where, RD is the radius of pocket curvature; R is the radius of curvature of the roller; LP 'is the height of the pocket ball table; LP is the height of the beveled edge of the cage pocket; LC is the total depth of the pocket; DP is the diameter of cage pocket; DP 'is the diameter of the bottom of the cage pocket; DW is the roller diameter; LW is the roller length; α Is the nominal contact angle of bearing; BC is the width of cage; Bc'is the width of the cage on the turning drilling surface; De is the outer race diameter; Assembly of cutting surface and cage end face α The angle is shown in Figure 2.
(2) Remove the 150 ° process cone top from the bottom of the traditional cage pocket, and the bottom of the pocket is flat, as shown in Figure 1 (B-B rotation diagram).
(3) Turn a plane perpendicular to the center line of the pocket. The parameters related to the machining plane are as follows (set the tool diameter as d)
3. Effect after improvement
Through the above improved design, the reliability of the complete set of bearings is greatly improved. Compared with the traditional self-aligning roller bearing design, it not only improves the rated load of the bearing, ensures the rotation accuracy of the bearing, improves the product quality, but also prolongs the service life of the bearing, and the effect is very remarkable.
More about KYOCM Self-aligning Ball Bearing:
Self-aligning ball bearings have two rows of balls, a common sphered raceway in the outer ring and two deep uninterrupted raceway grooves in the inner ring. They are available open or sealed. The bearings are insensitive to angular misalignment of the shaft relative to the housing, which can be caused, for example, by shaft deflection.
Features and benefits:
Accommodate static and dynamic misalignment
The bearings are self-aligning like spherical roller bearings or CARB bearings.
Excellent high-speed performance
Self-aligning ball bearings generate less friction than any other type of rolling bearing, which enables them to run cooler even at high speeds.
Minimum maintenance
Because of low heat generation, the bearing temperature is lower, leading to extended bearing life and maintenance intervals.
Low friction
Very loose conformity between balls and outer ring keeps friction and frictional heat at low levels.
Excellent light load performance
Self-aligning ball bearings have low minimum load requirements.
Low noise
Self-aligning ball bearings can reduce noise and vibration levels, for example, in fans.
2022-08-08