Grinding Technology Of Angular Contact Ball Bearings

Time：2020.07.22  Source：Roller Bearings Suppliers

1. Angular contact ball bearing inner ring grinding process

    In order to ensure the accuracy of bearing processing, the processing of bearing parts adopts a multi-cycle method, and the number of processing cycles of precision angular contact bearings even reaches more than 3 times. Generally speaking, the grinding of the inner ring of angular contact ball bearings with tolerance grades above P4 requires at least two cycles of rough grinding and fine grinding to meet the accuracy requirements, and the raceway processing requires super-precision or polishing. The basic route for grinding the bearing inner ring is: end surface → inner ring outer diameter surface (abbreviated as inner and outer diameter) → inner raceway → inner diameter surface (abbreviated as inner diameter). The end face, inner and outer diameter or inner channel are the machining datum planes, which require high precision and are the basis for ensuring the machining accuracy of the subsequent process.

    The formulation of the grinding process route requires comprehensive consideration of equipment capabilities, product characteristics, quality stability, and the determination of processing benchmarks. Different grinding methods use different process routes.WSBC Bearing 22207CC/W33 online, click here for more details.

2. Commonly used grinding methods for the inner groove of angular contact ball bearings

    2.1 Inner and outer diameter grinding groove

    Bearing inner and outer diameter grinding groove is a common method of bearing inner groove grinding. Electromagnetic centerless clamps are generally used. The supporting points are made of cemented carbide, and two are selected, and they are at a certain angle, and they are respectively in the third and fourth quadrants of the fixture. When adjusting the support, ensure that there is a certain eccentricity e between the center of the workpiece and the center of the fixture, and make the center of the workpiece in the fourth quadrant of the fixture. During the grinding process, the rotation of the fixture drives the workpiece to rotate at a uniform speed, the workpiece is supported by the limit effect, and there is a certain eccentricity between the workpiece and the fixture, and the ring can rotate smoothly. The grinding wheel needs to be shaped before grinding, and the outer edge of the grinding wheel is trimmed into the required shape with a diamond pen. The grinding wheel performs external cutting and grinding of the workpiece. The characteristics of the external cutting grinding are the large outer diameter of the grinding wheel, high linear speed and high grinding efficiency. The grinding direction is the same as the rotation direction of the workpiece.

    Processing features: 1) External cutting grinding is adopted, which has high grinding efficiency; 2) The inner and outer diameters are used as the grinding benchmark, which requires high precision of the inner and outer diameters; 3) The channel processing accuracy is average.

    2.2 Mo ditch of branch inner groove

    The principle of branch internal groove grinding is shown in Figure 3. This processing method looks similar to branch internal and external diameter grinding, but the processing principle is quite different. The branch inner groove grinding groove takes the inner groove as the supporting object, and the inner groove is both the reference surface and the grinding surface. There is no need to consider the accuracy of the inner and outer diameters during the machining process, and the groove grinding accuracy can be greatly improved. In addition, when the inner diameter surface is processed later, the method of supporting the inner groove is still used, which can effectively ensure the accuracy of the inner diameter surface. The grinding method still adopts external cutting grinding, and the processing efficiency is high. The location of the support and the eccentricity of the workpiece are the same as the inner and outer diameter of the support.

    Processing characteristics: 1) High processing accuracy, especially in the thickness variation Ki (wall thickness difference) between the inner ring channel and the inner hole; 2) External cutting grinding, high grinding efficiency; 3) Adopting inner support When the ditch grinding process removes the art, the outer diameter grinding process of the inner ring rib is saved, and man-hours are saved.

    2.3 Diameter grinding groove

    The principle of supporting inner diameter grinding groove adopts the front and rear supports to respectively support the inner diameter surface of the workpiece. The center of the workpiece is in the fourth quadrant of the fixture. The front and rear supports make the center of the workpiece and the center of the grinding wheel basically on the same level. The workpiece directly bears the grinding wheel. The cutting force given. This processing method is based on the inner diameter surface, and the accuracy of the channel is guaranteed by the accuracy of the inner diameter, and the processing of the inner diameter is based on the inner and outer diameters, so the inner and outer diameter processing requirements are extremely high. Grinding needs to strictly control the feed rate. When the feed rate is too large and exceeds the deformation resistance of the workpiece, it will easily cause the workpiece to deform, which makes it difficult to control the accuracy of the workpiece size and roundness.

Processing features: 1) Extremely high requirements for the inner and outer diameter and inner diameter accuracy of the previous process; 2) High requirements for operator skills; 3) Low production efficiency.Need WSBC Bearing 24044 CC/W33, click here for more information.

    2.4 Escape Method Mogou

    The internal groove grinding by escape method is a non-limiting grinding method, the principle is shown in Figure 5. The front support is an inner support, the eccentricity is in the first quadrant, and the rear support is an outer support, and the eccentricity is in the fourth quadrant. The angle between the two supports is β=30°～45°. When the grinding wheel feeds and grinds the workpiece, if the cutting force exceeds the clamping force of the electromagnetic centerless fixture, the workpiece will deviate from the outer support of the 4th quadrant. As the grinding force decreases, the workpiece falls back to the outer support for normal grinding. Repeat this until it is ground to the required size.

    Processing features: 1) High precision requirements for the inner and outer diameters and inner diameters of the previous process; 2) Suitable for grinding of thin-walled series bearings; 3) Small workpiece deformation; 4) Low production efficiency.

3. Conclusion

A comparative analysis of accuracy and efficiency is carried out through specific processing tests, and the conclusion is drawn:

1) The precision bearing ring grinding process adopts a multi-cycle processing method, which can reduce the grinding process stress, reduce the amount of deformation, and improve the processing accuracy.

2) The internal groove grinding of conventional precision ball bearings should adopt the branch internal groove grinding method to ensure the accuracy of internal groove grinding. Only one grinding of the inner and outer diameters can meet the design accuracy, avoiding multi-cycle processing and reducing processing Process, work efficiency is improved.

3) For thin-walled series and precision ball bearing inner groove processing with special precision requirements, the escape method can be used to grind the inner groove. Although the processing efficiency is slightly lower, the processing accuracy is high and the rejection rate is low.

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