Five Reasons for Cage Rupture in Crossed Roller Bearings

Time：2020.03.16  Source：Roller Bearings Suppliers

Crossed roller bearings are a special type of bearing with split inner ring and outer ring rotation. The divided inner ring or outer ring is fixed with the cross roller collar after the roller and the spacer are installed to prevent separation, so the operation is simple when installing the cross roller collar. Because the rollers are arranged in a cross, only one set of crossed roller collars can bear the load in all directions. Compared with the traditional model, the rigidity is increased by 3 to 4 times. At the same time, because the inner or outer ring of the cross roller bearing has a two-part structure, the bearing gap can be adjusted, and even if a preload is applied, a high-precision rotary motion can be obtained. Moreover, due to its special structure, it is usually used as an articulated bearing in industrial robots.

Crossed roller bearings' rollers are arranged at right angles to each other across the inner and outer wheels. They can support loads from all directions (such as axial, thrust or momentum loads) simultaneously. Because the rollers are in linear contact with the surface of the track, the bearing is less likely to deform elastically under load. This type of bearing is widely used in industrial robots, work machinery and medical facilities, etc., where high rigidity, tightness and high speed can still ensure accuracy.

In the crossed roller bearing, since the cylindrical rollers are arranged perpendicularly to each other through the spacer, the one crossed roller bearing can bear the load in all directions such as the radial load, axial load and moment load. The size of its inner and outer rings is minimized and has high rigidity, so it is most suitable for joints or rotating parts of industrial robots, rotating tables of machining centers, rotating parts of robots, precision rotating tables, medical Applications for machines, gauges, IC manufacturing equipment, etc.

Five major causes of cage breakage in crossed roller bearings:

1. Abnormal load of the cage may cause the cage to break. If the installation is not in place, tilting, excessive interference, etc., the clearance will be reduced, friction and heat will be increased, the surface will be softened, and abnormal peeling will occur prematurely. With the expansion of the peeling, the peeling foreign matter enters the pocket of the cage, resulting in retention The operation of the frame is retarded and additional load is generated, which aggravates the wear of the cage. If the situation continues to deteriorate, it may cause the cage to break.

2. Poor lubrication mainly refers to the operation of Luoyang cross roller bearings in a lean state, which is liable to form adhesive wear, which deteriorates the state of the working surface. The tears caused by adhesive wear easily enter the cage, which causes abnormal load on the cage, which may cause The cage is broken.

3. The intrusion of foreign objects is a common mode that causes failure of the cage. The invasion of foreign hard foreign matter intensifies the wear of the cage and generates an abnormal additional load, which may also cause the cage to break.

4. Creep phenomenon is also one of the reasons for the fracture of the cage. The so-called creeping multi-finger ferrule has a phenomenon in which the load point moves to the surrounding direction due to sliding when the interference amount of the mating surface is insufficient, resulting in the phenomenon that the ferrule moves relative to the shaft or the housing in a circumferential direction. Once the creep is generated, the mating surface is significantly worn, and the wear powder may enter the inside of the crossed roller bearing, forming abnormal wear, the peeling of the raceway, the wear of the cage, and the process of additional load, which may cause the cage to break.

5.Cage material defects (such as cracks, large foreign metal inclusions, shrinkage holes, air bubbles) and riveting defects (missing nails, pad nails or gaps between the two halves of the cage joint surface, severe riveting), etc. may cause retention The frame is broken, and countermeasures are taken to strictly control the manufacturing process.

Cross-roller bearing visual inspection considerations

1. Various cracks, such as raw material cracks, forging cracks, heat treatment cracks, and grinding cracks, etc. These cracks will become a source of stress concentration and rapidly expand during the operation of the crossed roller bearing in the future, causing the bearing to rupture. Life and work safety have a huge impact. In fact, for bearings for important applications, bearing factories have performed 100% magnetic or radiographic inspections on their components.

2.Various mechanical scars, such as abrasion, scratching, crushing, bumping, etc., will cause poor bearing installation, cause eccentric load and stress concentration, and reduce the rotation accuracy and service life.

3.Corrosion, black skin and pits, the latter two are defects that are easy to store moisture and dirt, and are very easy to develop into rust. Corrosion is a source of pollution that leads to poor installation, early wear and fatigue, and severe corrosion will cause the crossed roller bearings to be scrapped.

4.Peeling and folding, these two defects are not firmly combined with the base metal, and there is often a phenomenon of decarburization or depletion in the surroundings. The material is easy to fall, dent or wear, which has a bearing on the life and accuracy of the bearing. Very bad.

5.The quality of riveting or welding of the cage, mainly observe whether the rivet head is deviated, skewed, loose, lack of meat or "double eyelids", whether the welding position is correct, whether the welding spot is too large or too small, whether the welding is not strong or Excessive welding causes the rolling body to be stuck. Is the quality of the slope, edge trimming, caulking and chiseling of certain cages guaranteed, and whether the rolling body can fall freely out of the cage and can rotate freely, if these points are not satisfactory, If it is small, the noise and rotation accuracy of the crossed roller bearing will be reduced. If it is large, the cage may fall apart, causing mechanical failure or accident.