4 factors for influence slewing bearing capacity

Slewing ring failure form has two kinds, one is the raceway damage, the  second is broken teeth, and the raceway damage accounted for the proportion  of over 98%, so FRB Bearings said, the raceway quality is the core of the  quality of slewing bearing, there are many factors influencing the quality  of the slewing ring raceway.Among them, the raceway hardnesss, raceway  hardener depth,raceway radius of curvatureand and aceway contact angle are  undoubtedly the most important four influencing factors.They affect the  quality of the raceway in different ways and determine the bearing capacity  and service life of the slewing bearings.

Raceway hardness
The hardening hardness of the slewing bearing raceway has a great impact on  its rated static capacity. The minimum hardness specified in the standard  is HRC55, and the actual average quenching hardness is usually around  HRC57. Therefore, the actual bearing capacity of most of the slewing  bearing is higher than the theoretical value calculated according to  HRC55.When the hardness is lower than HRC53, even if the safety factor of  1.2 is left, it is not safe to use. In particular, when the hardness is  only HRC50, the safety factor of 1.7 is useless, which is very  dangerous.Lack of hardness can easily cause the failure of slewing bearing,  from the beginning of the pitting on the surface of the raceway to the end  of collapse.



Raceway hardener depth
At present, there is no nondestructive testing method for the hardened  layer depth of the raceway, which is mainly guaranteed by the technology  and equipment.When the slewing bearing bears external loads, the contact  between the steel ball and the raceway becomes surface contact.

Raceway radius of curvature
The curvature radius of the raceway here refers to the curvature radius of  the raceway in the vertical profile. The ratio t(generally 1.04~1.08) of  the radius of the steel ball also significantly affects the rated static  and dynamic capacity of the slewing bearing (life Lh).

Raceway contact angle
The contact angle refers to the angle between the contact point of the ball  on the raceway and the line between the ball center of the ball and the  slewing bearing radial profile (horizontal plane).If both the original  contact angle and the gap are large, the actual contact angle will also  increase. At this time, the contact elliptical surface will be beyond the  raceway edge, and the actual force of the raceway will be higher than the  theoretical calculated stress, resulting in the collapse of the raceway  edge and the failure of slewing bearing.