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Carburizing and quenching method for cylindrical gear

A cylindrical gear, carburizing and quenching technology, applied in the field of heat treatment, can solve the problems of reducing gear quenching deformation, reducing phase transition stress, and increasing deformation tendency, so as to reduce heat treatment deformation, reduce manufacturing cost, and reduce grinding time Effect

Inactive Publication Date: 2015-04-08
CRRC QISHUYAN INSTITUTE CO LTD
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Problems solved by technology

The press quenching process can correct any deformation of the gear formed in the process of carburizing and quenching, but it needs to be equipped with a quenching press, and a special press quenching tool is required for the design of the gear. The production efficiency is low and the cost is high, and it is only suitable for mass-produced gears; The hot oil graded quenching process can reduce the phase transformation stress formed in the quenching and cooling process, and achieve the purpose of reducing the gear quenching deformation, but it cannot improve the deformation caused by the existence of thermal stress during the carburizing and quenching process of the gear, and the process has a great impact on the quenching process. Strict control requirements, improper process control will increase the tendency of deformation, and even reduce the performance of heat treatment process

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  • Carburizing and quenching method for cylindrical gear
  • Carburizing and quenching method for cylindrical gear
  • Carburizing and quenching method for cylindrical gear

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Embodiment Construction

[0029] The spur gear of the present embodiment is the locomotive driven gear, as figure 1 As shown, the material is low-carbon alloy steel 18CrNiMo7-6, its Ac1 point is 738°C, Ac3 point is 815°C, the original heat treatment process is as follows Figure 4 As shown, direct carburizing-high temperature tempering-quenching treatment-low temperature tempering, the deformation is obvious, a large grinding allowance is required, and the thickness of the carburized layer is difficult to control.

[0030] To this end, the applicant has carried out in-depth test analysis. Studies have shown that the above-mentioned steel materials will change from elastic deformation to plastic deformation when heated above 500°C, and irreversible plastic deformation will occur, and finally become heat treatment deformation and remain. Usually, when the steel is heated rapidly, the initially heated part, that is, the outer side of the steel, first enters the plastic deformation temperature zone, becau...

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Abstract

The invention relates to a carburizing and quenching method for a cylindrical gear, and belongs to the technical field of heat treatment. The method comprises the following steps: heating until the temperature exceeds elastic-plastic transformation temperature of low-carbon steel for primary preheating; heating until the temperature is less than the phase-transition temperature Ac1 of the low-carbon steel for preheating again; performing carburizing, high-temperature tempering, quenching, and low-temperature tempering. According to the carburizing and quenching method for the cylindrical gear, effective measures for inhibiting or removing deformation are respectively performed for a plurality of process stages and supplement each other and are organically combined, so that the deformation of the cylindrical gear carburizing and quenching thermal treatment can be obviously reduced, the preset grinding allowance of the gear can be properly decreased, and as a result, the gear grinding time is reduced, and conditions are created for lowering the gear manufacturing cost.

Description

technical field [0001] The invention relates to a carburizing and quenching method, in particular to a carburizing and quenching method for a cylindrical gear capable of improving heat treatment deformation, and belongs to the technical field of heat treatment. Background technique [0002] Due to the existence of thermal stress and phase transformation stress in gear carburizing and quenching, deformation is almost inevitable. The heat treatment deformation of cylindrical gears is mainly manifested in four aspects: expansion and contraction, taper, ellipticity and end face distortion. There are many factors affecting heat treatment deformation, including the structural shape of the part itself, raw materials and metallurgical quality, residual stress of forging and machining, charging method, heat treatment process and equipment, etc. In the past, to deal with the large heat treatment deformation of gears, measures such as increasing the grinding allowance in the design an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23F17/00C21D1/18C21D9/32C23C8/22
Inventor 陈强刘康吴刚刘聪敏
Owner CRRC QISHUYAN INSTITUTE CO LTD
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