Best China Small Slewing Bearing
1.Why does the slewing bearing get stuck and have a dead point with no load and normal rotation load?
The no-load bearing can rotate normally, and the clearance, warpage, ellipse, and groove shape are directly related to the contact point.
Especially after the load, the contact point of the channel and the shape of the channel are very critical and very obvious. If it rotates before no-load, it is because there is enough clearance to affect the rotation, but after the slewing bearing is stressed, the contact point theoretically moves in a circle along the parallel trajectory of the upper and lower contact points of the bearing.
In fact, the shape of the channel is warped. Curve and ellipse, at this time, the contact point is jumping and irregular, which is equivalent to the jumping and turning of the steel ball ups and downs, so that it enters an infinite loop, resulting in stuck.
Generally speaking, the slewing bearing in the crane bearing, crane bearing, bucket turbine bearing, fixed crane slewing bearing, stacker-reclaimer bearing and crane bearing and other large marine crane bearings, the failure occurred in the early stage, according to the failure level Basically divided into three categories
The failure of the large bearing was initially manifested because of the sound and abnormal sound. Eliminate interference, such as rotation interference, gear interference, good dust baffles, etc. The reasons for the noise are mostly abnormal load, ball impact sound, uneven contact between the channel and rolling elements, deformation, etc.
If it is a new slewing bearing, it means the channel There are ovals or warping, and stress relief is not complete. It is a manufacturing defect. If possible, the bearing should be disassembled and the groove fitting should be re-ground.
If it is sharp and harsh, accompanied by vibration, swing, or jitter after the abnormal noise, it means that the slewing bearing has penetrated into the core of the fault, the rolling elements are broken, the channel is strained, and even the hardness layer falls off. At this time, the bearing has repair value.
If the equipment has a spare bearing, it should be replaced in advance. The old bearing is disassembled and repaired, and the service life can reach more than 80% of the new bearing. In fact, many spare bearings are used as new bearings for emergency use.
If there is no spare bearing, on the basis of confirming the drawings and model, strengthen the maintenance and maintenance of the old bearing, and start the customization of the new bearing, which generally takes 60-80 days.
Bearing rotation begins to be difficult, stuck, stuck or even stuck. Basically, it is announced that the bearing has fallen into the nest. At this time, it can only be pulled hard, cleaned with kerosene, or rotated back and forth. It is the factory that has to work three shifts and pay three times and four times the cost to manufacture it in a short time.
2.Four-point contact ball bearings and crossed roller bearings
Comparison of working conditions and selection and positioning of four-point contact ball bearings and crossed roller bearings. Simply speaking, it is very important to choose a four-point ball bearing or a crossed roller bearing according to the needs of the working conditions.
In terms of precision design, crossed roller bearings are more obtainable, and in terms of rotational flexibility, four-point contact ball bearings are better.
In the accuracy level, when the speed is higher than 10rpm, and there are certain requirements for noise, such as when the requirement is less than 80 decibels, the four-point contact ball is the first choice, and the PTFE cage or copper cage is selected.
In terms of rigidity and stability, crossed roller bearings are the preferred choice, but the rotational speed should be low, generally below 8rpm. And since the cross rollers are arranged in a 1:1 ratio, noise is unavoidable when reaching high speeds, because the friction and impact of the rollers are unavoidable.
At the same time, we must pay attention to the use of lubricating oil, and grease is indispensable. Gear grinding, groove grinding, high-precision steel balls, deep groove ball grooves on the inner ring, four-point contact ball grooves on the outer ring, and two-point contact are also ways to reduce noise.
