Cryogenic heat treatment technology for improving performances of countershaft gear

A technology of cold and heat treatment and cryogenic treatment, applied in heat treatment furnaces, heat treatment equipment, metal material coating technology, etc., can solve the problems of large deformation and low surface hardness, so as to improve the service life, reduce quenching deformation, and enhance the surface The effect of hardness

Inactive Publication Date: 2016-03-16
张贺佳
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the heat treatment industry mostly adopts the carburizing and quenching process for intermediate shaft gears. Due to the large residual stress generated by oil quenching, the deformation is large, and the cryogenic process is rarely used after quenching, and a large amount of residual austenite is produced in the carburized layer. , leading to low surface hardness

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Preheat the machined countershaft gear in a box furnace for 30 minutes; send the preheated countershaft gear into a multi-purpose furnace for carburization, the carbon potential is 0.85Cp, and the carburizing temperature is 900°C; then pull it from the back room Go to the front room for isothermal quenching in the salt bath. The quenching temperature is 815°C and the salt bath temperature is 260°C. The speed of / min is reduced to -196°C for 1 hour, and then the countershaft gear in the cryogenic box is placed in liquid nitrogen for 7 hours, and finally the countershaft gear is taken out and placed at room temperature to return to temperature. Send the intermediate shaft gear that has returned to room temperature into a box-type tempering furnace, and temper it twice at 165°C for 160 minutes.

[0016] After processing according to the above process, the straightness correction is within 0.02mm and the surface hardness is 740HV.

Embodiment 2

[0018] Preheat the machined intermediate shaft gear in a box furnace for 50 minutes; send the preheated intermediate shaft gear into a multi-purpose furnace for carburization, the carbon potential is 0.80Cp, and the carburizing temperature is 870°C; Go to the front room for isothermal quenching in the salt bath. The quenching temperature is 830°C and the salt bath temperature is 300°C. The speed of / min is reduced to -110°C for 2 hours, and then the countershaft gear in the cryogenic box is placed in liquid nitrogen for 10 hours, and finally the countershaft gear is taken out and placed at room temperature to return to temperature. Send the countershaft gear that has returned to room temperature into a box-type tempering furnace, and temper it twice at 190°C for 120 minutes.

[0019] After processing according to the above process, the straightness correction is within 0.02mm and the surface hardness is 730HV.

Embodiment 3

[0021] Preheat the machined intermediate shaft gear in a box furnace for 35 minutes; send the preheated intermediate shaft gear into a multi-purpose furnace for carburization, the carbon potential is 0.85Cp, and the carburizing temperature is 880°C; Go to the front room for isothermal quenching in the salt bath. The quenching temperature is 820°C and the salt bath temperature is 290°C. The speed of / min is reduced to -180°C for 1 hour, and then the intermediate shaft gear in the cryogenic box is placed in liquid nitrogen for 7 hours, and finally the intermediate shaft gear is taken out and placed at room temperature to return to temperature. Send the countershaft gear that has returned to room temperature into a box-type tempering furnace, temper it twice at 170°C, and keep it warm for 180 minutes.

[0022] After processing according to the above process, the straightness correction is within 0.02mm and the surface hardness is 735HV.

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Abstract

The invention discloses a cryogenic heat treatment technology for improving performances of a countershaft gear. According to the technology, a salt bath quenching technology and a cryogenic technology are combined, so that the defects that the countershaft gear is liable to quenching deformation and is low in surface hardness are improved, and the service life of a countershaft is prolonged. The cryogenic heat treatment technology for improving performances of the countershaft gear is characterized by comprising the specific steps of cleaning, preheating, carburization, salt bath quenching, cryogenic treatment and secondary tempering. Compared with the prior art, the technology has the advantages that in the quenching stage, salt bath quenching is combined with a novel technology of cryogenic treatment, so that the deformation degree of the countershaft gear after carburization and quenching is enabled to be small, and the surface hardness is greatly improved.

Description

technical field [0001] The invention relates to the technical field of carburizing and quenching, salt bath isothermal quenching and deep cooling, specifically a cryogenic heat treatment process for improving the performance of intermediate shaft gears Background technique [0002] The intermediate shaft gear is a shaft in the engine gearbox. The shaft and the gear are integrated. The function is to connect other shafts, and then the driver performs a transformation action to choose to mesh with different gears, so as to output different speeds. In the engine The role of the intermediate shaft is crucial, and the gear on the intermediate shaft is the most important. [0003] At present, the heat treatment industry mostly adopts the carburizing and quenching process for intermediate shaft gears. Due to the large residual stress generated by oil quenching, the deformation is large, and the cryogenic process is rarely used after quenching, and a large amount of residual austeni...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/32C23C8/22C21D1/20C21D6/04
CPCC21D9/32C21D1/20C21D6/04C23C8/22
Inventor 张贺佳惠斌吕美娇陈巧云马素娟陈永利李建杰李东亮
Owner 张贺佳
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