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Analysis And Countermeasures Of Early Broken Teeth Of Single Row Ball Slewing Bearing
Sep 08, 2017

Analysis and countermeasures of early broken teeth of Single Row Ball Slewing Bearing

There are two main reasons for the early failure of the single bearing ball slewing bearing:

One is a single ball rotation bearing teeth; the second is the roller drive damage. Among them, the single row of ball bearings broken teeth is the main reason, accounting for more than 90%, and the vast majority occurred in the excavator factory within six months. This is not only plagued the single-ball ball bearing factory product quality reputation, but also on the OEM factory product market adversely affected, so seriously solve this problem is a single ball slewing bearing factory and OEMs common goals and responsibilities, But also the two sides to further cooperation and common development of the fundamental guarantee.

What is the root cause of the early failure of a Single Row Ball Slewing Bearing due to broken teeth?

Design issues; manufacturing problems, material problems; assembly problems or use problems. Through the following phenomenon is not difficult to find a single row of ball bearings early cut teeth of the nature of the problem lies:

1, in the past 12 years, double positive single ball ball bearing factory for a variety of host supporting single ball ball slewing bearing more than 20,000 sets, in addition to excavator industry, only a single row of ball slewing teeth broken teeth records, and Is happening in the late. Of course, the excavator's working conditions than the tower crane, car cranes and other most of the use of single-ball ball bearings in the industry's host conditions to be harsh, faster rotation, the impact load is also large, the possibility of teeth correspondingly large Some, it is also an indisputable fact. Therefore, the excavator with a single row of ball slewing bearing modulus than the same raceway diameter of the other industry host with a single ball slewing bearings to large gear, and is hardened surface (generally in the 47HRC ~ 58HRC between the choice of different hardness section) , Basically meet the excavator on the single ball slewing bearing gear requirements. Although the statistics show that the excavator with a single row of ball bearings early break the probability of teeth is greater than the other host, but also limited to very few two or three excavators, most of the models rarely have a single row of ball bearings early break The

2, from our mastery of the data analysis, the vast majority of 20 to 22 ton at home and abroad excavator use single row ball bearing gear modulus are 10mm (or diameter section = 2.5), heat treatment and accuracy level is basically the same, domestic Excavators generally use standard tooth height and standard pressure angle

It can be seen that the circumferential force of the gear can meet the tonnage of the excavator on the Single Row Ball Slewing Bearing gear load requirements, but in this level of individual models of Single Row Ball Slewing Bearing early tooth breaking rate is as high as 2% Some models do not happen.

Analysis and Countermeasure of Broken Teeth of Single Row Ball Rotating Bearing

It is found that most of the broken teeth occur in the upper half of the tooth width direction, and more than half of the fracture surface intersects the upper end face of the teeth and becomes 45 ° ~ 60 °. Around the angle, even if the whole tooth off the crack is also due to the top-down expansion. The plastic deformation caused by the extrusion of the gear is also quite obvious, and the upper part is much more serious than the lower part, the whole circle tooth width has varying degrees of change, from bottom to top, from the root to the top tooth slot width increase.

Whether we can think that: the excavator Single Row Ball Slewing Bearing early break the force of the teeth is not the circumferential rotation driving force, but with the meshing of the pinion to its radial pressure, and squeeze when the pinion The axis is not parallel to the Single Row Ball Slewing Bearing gear axis. This force is generated in the excavation process of the ground against the bucket of the reaction force, because the single row of ball slewing bearing gap, and Single Row Ball Slewing Bearing inner and outer ring were connected to the upper and lower parts under the action of the overturning moment, will occur in the single ball The relative inclination of the rotary bearing through the axial section of the boom also produces a relative displacement in the radial direction of the Single Row Ball Slewing Bearing in the opposite direction of the boom, and the displacement is equivalent to the radial clearance of the Single Row Ball Slewing Bearing. In the opposite direction of the boom, when the gap between the two sides is too small, the displacement has not yet been completed, the pinion will be pressed on the large gear, this case should be a single ball slewing bearing The load on the raceway is supported by the gear, and the axis of the original gear is further aggravated by the reaction of the pinion, so that the pressing force acting on the large gear is concentrated in the upper part of the tooth width. The gears are compensated by the plastic deformation to compensate for the gap between the teeth side. With the further running of the single race ball bearing raceway, the radial clearance gradually increases, and the deformation is limited. Through the force analysis can be seen: the pinion on the big gear of the squeeze force is the ground against the bucket of the reaction force several times or even ten times, and the role of the force on the tooth profile will be amplified again, the pressure angle The larger the magnification factor is. This is twice the magnified force to cause the size of the gear teeth.