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Accurate control method for surface hardness, roughness and white layer depth of engine nitrided gear

A technology of nitriding gears and surface hardness, which is applied to components with teeth, belts/chains/gears, gear teeth, etc., which can solve the problems of poor repeatability, difficulty in stabilizing quality control, and difficulty in achieving parts with surface hardness and nitriding depth and other problems, to achieve the effect of improving meshing conditions, suitable for large-scale mass production applications, and improving surface roughness

Active Publication Date: 2021-03-05
ZHONGNAN TRANSMISSION MACHINERY FACTORY CHANGSHAAVIATION IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But when the white layer depth is reduced, it is difficult to make the surface hardness and nitriding depth meet the technical drawing requirements of the part itself
Moreover, in the process of processing, there are often problems such as difficult to control the quality stably and poor repeatability.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0023] Aiming at the technical problems existing in the existing nitriding gear preparation method, the present invention focuses on surface modification of parts to improve meshing conditions. By reducing the roughness of the nitriding gear, controlling the surface hardness, and reducing the depth of the white layer, it helps to prolong the service life of the gear pair combined with the nitriding gear and the carburizing gear, and can effectively reduce the gap between the nitriding gear and the carburizing gear of the engine. The hardness difference between them, avoiding the thicker white layer will cause uneven hardness on the surface of the gear (causing stress concentration of the parts during the meshing process) and high roughness will easily cause high wear, and by controlling the nitrided white layer and surface hardness effectively Reduced wear due to stress concentration during engagement.

[0024] However, the depth of the white layer is closely related to the su...

Embodiment 1

[0041] Nitriding of the 86-tooth gear shaft of a certain type of engine requires the nitriding depth to be 0.1-0.2mm, the nitriding surface hardness HV≥800, and the depth of the white layer after nitriding to be ≤0.015mm according to relevant standards. For example, control the nitriding surface hardness HV800~860 (HRC64~66), the nitriding white layer depth≤0.006mm, and the surface roughness Ra≤0.8.

[0042] In order to obtain the above results, the present embodiment provides a method for accurately controlling the surface hardness, roughness and white layer depth of the following engine nitriding gears, including the following steps:

[0043] (1) Stabilize the parts after nitriding hobbing at a temperature of 550±10°C for 2 to 4 hours;

[0044] (2) After the parts are stabilized, the teeth are ground, and the roughness of the grinding teeth is guaranteed to be Ra≤0.4;

[0045] (3) Zinc-based phosphating process is used for surface activation before nitriding of parts after ...

Embodiment 2

[0050] Using the same raw materials as in Example 1, the difference between the treatment method of this example and Example 1 is that the phosphating time is 4min, the nitriding temperature is 490°C, and the nitrogen potential of the first stage is set to be 0.85. The nitriding time is 8h, the second section sets the nitriding nitrogen potential to 0.25, and the nitriding time is 24h.

[0051] After nitriding, it is found that the metallographic structure is 2~3 grades, the surface roughness is Ra0.529~0.596, the white layer depth is 0.002~0.003mm, the depth is 0.16mm, and the surface hardness is 835~855HV.

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Abstract

The invention provides an accurate control method for the surface hardness, roughness and white layer depth of an engine nitrided gear. The method comprises the following steps of (1) stabilizing thenitrided gear; (2) carrying out gear grinding; (3) carrying out phosphating treatment; and (4) carrying out primary nitriding treatment under the condition that the KN is 0.8-1.0, and then carrying out secondary nitriding treatment under the condition that the KN is 0.2-0.4. According to the method, the surface hardness, the roughness, the white layer depth and the nitriding depth can be accurately controlled, the process is simple, the quality of a treated workpiece is stable, and the method is suitable for large-scale batch production and application.

Description

technical field [0001] The invention relates to a method for accurately controlling the surface hardness, roughness and white layer depth of the shallow nitriding surface of a 30Cr3MoA steel engine nitriding gear. Background technique [0002] 30Cr3MoA steel is a nitriding gear steel commonly used in aviation products. After nitriding, a hardened layer with high hardness can be obtained on the surface, and it has excellent strength and toughness. [0003] This material is a commonly used nitrided material. According to relevant foreign and domestic standards, surface activation is required before nitriding to ensure the uniformity of the depth of the nitrided layer on the surface of the part. After nitriding, the surface hardness can reach above HV800, but with the surface activation , the surface roughness of parts nitrided will increase. And aviation products involve an engine gear part, which is a nitriding part, and it is matched with a carburized part. The hardness of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/26C23C8/02C23C22/00B23F5/02
CPCC23C8/26C23C8/02C23C22/00B23F5/02
Inventor 唐梦兰李栋张志华曹永香
Owner ZHONGNAN TRANSMISSION MACHINERY FACTORY CHANGSHAAVIATION IND
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