The NSK oil groove of the bearing inner ring crack formation may have the following two reasons:
(1) than the tip of the turning tool head, resulting in local stress concentration during heat treatment; In addition, because the existence of the decarburized layer of oil trench also weakens the strength of the material here, resulting in a ditch along the circumferential direction of cracking. The crack is in the oil groove quenching cracks.
(2) the ditch caused a sharp focus on the stress (heat treatment) and the roll Road, ribs grinding stress superimposed crack. Recommendations to improve the turning and grinding process, ie to avoid the sharp corners of the oil groove, reduce grinding stress. In addition, to strengthen the protection of the atmosphere, reduce the heat treatment of decarburization in order to avoid such cracks.
NSK bearing inner ring face and the inner diameter of the steps of the angle at the presence of the sharp edges here, the heat can easily cause stress concentration, resulting in a distribution similar to the oil groove along the circumferential direction crack; In addition, here concentrated stress and a large nose and the inner diameter surface grinding stress superposition will result in different forms of crack. Recommended to optimize the design (or processing) technology, so that the angle of the chamfer and face smooth as possible, to avoid heat stress here too concentrated a result of the quench cracking.
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