Causes and countermeasures of grinding defects on bearing surface



In the process of grinding, the working surface of bearing is ground by high-speed rotating grinding wheel, so if the equipment is not operated and adjusted according to the work instruction, various defects will appear on the working surface of bearing, which will affect the overall quality of bearing. In precision grinding of bearings, due to the high requirements of roughness, the grinding marks on the working surface can often be observed with the naked eye, mainly as follows.

The reason for the appearance of cross helix trace is mainly due to the poor flatness of the bus of the grinding wheel and the concave-convex phenomenon. During grinding, the grinding wheel is only partially in contact with the workpiece. When the workpiece or the grinding wheel moves back and forth several times, the cross helix will reappear in the workpiece and can be observed by the naked eye. The pitch of these spirals is related to the speed of the workpiece table and the rotational speed of the workpiece, and it is also related to the non-parallel axis of the grinding wheel and the guide rail of the table.

(1) the main reason for the formation of spiral line

1. The grinding wheel is poorly dressed, the corners are not chamfered, and the cooling liquid is not used for dressing;

2. There is too much lubricating oil in the guide rail of the workbench, which causes the workbench to float;

3. The accuracy of the machine tool is not good;

4. Excessive grinding pressure.

(2) The reasons for the formation of spiral lines

1. The V-shaped guide rail has poor rigidity, and when grinding, the grinding wheel deviates, only the edge of the grinding wheel contacts the working surface;

2. When dressing noisy wheels, the reversing speed of the workbench is unstable and the accuracy is not high, which makes one edge of the grinding wheel slightly trimmed;

3. The rigidity of the workpiece itself is poor;

4. There are broken and flaked sand particles on the grinding wheel and iron chips under workpiece grinding attached to the surface of the grinding wheel, so the dressed grinding wheel should be washed or scrubbed with cooling water;

5. The grinding wheel is not well dressed, and there are local bulges.

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