There are many technical indicators that reflect the accuracy of slewing bearings and slewing bearings, such as axial clearance and radial clearance, end jump and radial jump, parallel difference and inside and outside difference, roughness, dimensional tolerance, position tolerance, etc. So, do you know what the tolerance of slewing ring refers to?
The dimensional accuracy and rotation accuracy of the slewing bearing are based on ISO and JIS standards. For machinery that requires high precision and high-speed operation, it is recommended to use bearings with accuracy grade 5 or above. Deep groove ball bearings, radial thrust ball bearings or cylindrical roller slewing bearings are suitable for machinery with high operating accuracy.
The inner diameter and outer diameter of the rolling slewing ring are manufactured according to standard tolerances. The tightness of the slewing ring inner ring and shaft, outer ring and seat hole can only be achieved by controlling the tolerance of the journal and the tolerance of the seat hole. Tolerance includes shape tolerance and position tolerance.
When the dimensional tolerance accuracy is determined, the shape tolerance has an appropriate value, that is, generally about 50% of the dimensional tolerance value is used as the shape tolerance value; about 20% of the dimensional tolerance value in the instrument industry is used as the shape tolerance value; heavy industry Approximately 70% of the dimensional tolerance value is used as the shape tolerance value. This shows that. The higher the dimensional tolerance accuracy, the smaller the proportion of the shape tolerance to the dimensional tolerance. Therefore, when designing the size and shape tolerance requirements, except for special circumstances, when the dimensional accuracy is determined, the 50% dimensional tolerance value is generally used as the shape tolerance value , Which is not only good for manufacturing but also good for ensuring quality.
There is also a certain relationship between shape tolerance and position tolerance. From the perspective of the cause of the error, the shape error is caused by machine tool vibration, tool vibration, spindle runout, etc.; while the position error is caused by the non-parallelism of the machine tool rails, the non-parallel or non-perpendicular tool clamping, and the effect of clamping force. As a result, from the definition of tolerance zone, the position error includes the shape error of the measured surface. For example, the parallelism error contains the flatness error, so the position error is much larger than the shape error. Therefore, under normal circumstances, when there is no further requirement, the position tolerance is given, and the shape tolerance is no longer given. When there are special requirements, the shape and position tolerance requirements can be marked at the same time, but the marked shape tolerance value should be less than the marked position tolerance value, otherwise, the parts cannot be manufactured according to the design requirements during production.
The slewing bearing and slewing ring have high precision, which represents the level of precision and processing technology, which means higher value. They are generally used for precision machine tools, precision equipment and high-precision instruments to achieve measurement and control, positioning and pointing. The runout is controlled at 0.02, ~ 0.05, the clearance value is controlled at 0.01-0.06, the roughness is controlled at Ra1.6/0.8, the hardness is uniformly distributed, the parallel difference is controlled at 0.015, and the dimensional tolerance must be in accordance with the requirements of the drawing.