In the heat treatment of the bearing ring, due to the different degree of thermal expansion of the outer surface and inner metal of the bearing ring, and the large thermal stress and tissue stress generated in the ring, resulting in serious deformation of the ring in the diameter direction and increased roundness error. For these problems, the heat treatment test of the bearing ring was carried out, with the cold treatment process added to the heat treatment. The effect of cold treatment on the residual stress, retained austenite and roundness of the bearing ring was analyzed. The research results show that: because the degree of deformation of the bearing ring is affected by the residual stress, the cold treatment process can significantly improve the residual stress on the bearing ring surface and reduce the deformation. The cold treatment process can accelerate the transformation from retained austenite to martensite in the bearing ring, reduce the content of retained austenite, refine the martensite structure and promote the precipitation of network carbide. The cold treatment after quenching also can improve the roundness accuracy of the bear outer ring and the bearing ring raceway, and ensure the processing quality and dimensional stability, which will be a significant benefit in industrial applications.

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The flat cross wedge rolling is an advanced forming process, which is used to produce thread shafts. In this work, a finite element model of flat cross wedge rolling thread shafts was established by the DEFORM-3D, and the effect of the forming angle, spreading angle, helix angle and flank angle on forming quality are investigated. The research results show that the forming angle, spreading angle, helix angle have a significant influence on the position of the die wedge-in point. The angle designed wrongly makes the die wedge-in point unable to be aligned correctly, causing defects such as slipping in the process, repeated rolling of formed thread, thin or incomplete tooth shapes. The flank angle mainly makes an impact on the axial force. Reducing the right flank angle or increasing the left flank angle can effectively improve the imbalance of axial force to obtain high-quality thread shafts. Through the experiment of flat cross wedge rolling thread shafts, the data comparison demonstrates that the error of the external dimension of formed parts is small, proving the reliability of the rolling parameter selection.

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