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Heat treatment technology for improving the surface hardness of precise rolling ball bearing

A rolling ball bearing and surface hardness technology, applied in the field of precision rolling ball bearings, can solve the problems of insufficient hardness, small deformation and high scrap rate, and achieve the effect of inhibiting the factors that cause material brittleness, increasing the hardness gradient and reducing the scrap rate.

Inactive Publication Date: 2011-08-31
SHANGHAI DIANJI UNIV
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AI Technical Summary

Problems solved by technology

[0002] The heat treatment method of high hardness precision rolling ball bearings usually adopts quenching, low temperature tempering and ice cooling treatment. For precision rolling ball bearings with ultra-high hardness (hardness greater than 1000HV0.1), this process often cannot meet the hardness requirements
In the prior art, surface isothermal nitriding is used to make the surface of precision rolling ball bearings reach ultra-high hardness. The advantages of this nitriding process are high hardness and small deformation of the bearing surface; poor transition
High hardness is easy to cause brittleness, and poor transition will reduce the bonding force between the tissues in the nitrided layer, which will cause the nitrided layer on the surface of the bearing to fall off. It is scrapped due to the faintly visible white point defects with naked eyes, and the scrap rate is high

Method used

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Embodiment

[0021] The raw material GCr15 steel is quenched and tempered, the quenching temperature is 840°C, the holding time depends on the size of the part (as long as the bearing core structure can be heated evenly), the tempering temperature is 630°C, and the holding time depends on the size of the part (As long as the structure of the bearing core can be heated evenly), the metallographic structure analysis shows that the quenched and tempered metallographic structure is uniform tempered sorbite;

[0022] Process the quenched and tempered raw materials into rolling ball bearings;

[0023] Clean the rolling ball bearing until there is no oil on the surface of the bearing, dry it and put it into the nitriding furnace;

[0024] Carry out three-stage nitriding, the first stage adopts low temperature and high nitrogen potential, heats up to 510°C, feeds ammonia gas, the ammonia decomposition rate is 18% to 25%, and keeps warm for about 25 hours; the second stage adopts high temperature a...

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Abstract

The invention provides a heat treatment technology for improving the surface hardness of a precise rolling ball bearing. The heat treatment technology includes the steps of quenching-tempering treatment, processing-shaping, cleaning-drying, and nitriding treatment in sequence. The heat treatment technology is characterized in that nitriding treatment adopts three-stage nitriding, wherein a low-temperature high-nitrogen type is adopted in the first stage, a high-temperature high-nitrogen type is adopted in the second stage and a high-temperature low-nitrogen type is adopted in the third stage. The heat treatment technology can remarkably restrain various factors causing material fragility in a nitride layer of GCr15 steel and avoid the formation of Zeta phase (Fe2N), thus greatly improving the quality of the precise rolling ball bearing after nitriding treatment and remarkably lowering the rejection rate of the precise rolling ball bearing.

Description

technical field [0001] The invention relates to a heat treatment method for the surface of a precision rolling ball bearing, in particular to a precision rolling ball bearing whose surface requires high hardness. Background technique [0002] The heat treatment method of high hardness precision rolling ball bearings usually adopts quenching, low temperature tempering and ice cooling treatment. For precision rolling ball bearings with ultra-high hardness (hardness greater than 1000HV0.1), this process often cannot meet the hardness requirements. In the prior art, surface isothermal nitriding is used to make the surface of precision rolling ball bearings reach ultra-high hardness. The advantages of this nitriding process are high hardness and small deformation of the bearing surface; Poor transition. High hardness is easy to cause brittleness, and poor transition will reduce the bonding force between the tissues in the nitrided layer, which will cause the nitrided layer on t...

Claims

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Application Information

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IPC IPC(8): C23F17/00C23C8/26
Inventor 陆卫倩刘秦
Owner SHANGHAI DIANJI UNIV
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