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Method for controlling hardness of spline after carburizing and integral quenching of gear

A technology of overall quenching and hardness control, applied in the direction of heat treatment process control, manufacturing tools, improvement of process efficiency, etc., can solve the problem of high surface hardness of splines, reduce the difficulty of finishing and improve the quality of gear products.

Active Publication Date: 2022-02-18
XIAN COAL MINING MACHINERY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this method, the allowance design of the gear spline is carried out before the gear carburizing to prevent the increase of the hardness of the spline after the overall quenching due to the increase of the carbon content in the transition zone of the carburized layer at the gear spline. The carbon coating protects the splines of the gears to prevent the carbon potential protection of the carburizing gear atmosphere to promote the carbonization of the surface of the splines, which solves the problem of high surface hardness of the splines caused by the carbonization of the surface of the splines. It can be used after low temperature tempering Local surface induction tempering treatment method, through precise control of tempering temperature, prevents the problem of high spline hardness caused by the upper limit of the chemical composition of raw materials

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  • Method for controlling hardness of spline after carburizing and integral quenching of gear
  • Method for controlling hardness of spline after carburizing and integral quenching of gear

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] This embodiment includes the following steps:

[0042] Step 1. Die forging the cylindrical steel raw material after heating to obtain a forged gear blank; the material of the cylindrical steel raw material is 17Cr2Ni2MoA low-carbon alloy steel; The temperature is 880°C;

[0043] Step 2: Normalizing and high-temperature tempering the forged blank of the gear part obtained in Step 1 in sequence to obtain a blank; the temperature of the normalizing is 930°C, and the temperature of the high-temperature tempering is 650°C;

[0044] Step 3: Carry out hobbing and contour processing on the blank obtained in step 2 to obtain a green body; during the hobbing and contour processing, a machining allowance is reserved at the spline; the reserved machining allowance at the spline satisfies : The thickness of the machining allowance is 3.8mm;

[0045] Step 4. Carburizing the blank obtained in step 3 to obtain a carburized gear blank; the carburizing uses a nitrogen-methanol carburiz...

Embodiment 2

[0054] This embodiment includes the following steps:

[0055] Step 1. Die forging the cylindrical steel raw material after heating to obtain a forged gear blank; the material of the cylindrical steel raw material is 18CrMnNiMoA low-carbon alloy steel; The temperature is 900°C;

[0056] Step 2. Carrying out normalizing and high-temperature tempering in turn on the forged gear blank obtained in step 1 to obtain a blank; the normalizing temperature is 920°C, and the high-temperature tempering temperature is 670°C;

[0057] Step 3: Carry out hobbing and contour processing on the blank obtained in step 2 to obtain a green body; during the hobbing and contour processing, a machining allowance is reserved at the spline; the reserved machining allowance at the spline satisfies : The thickness of the machining allowance is 4.9mm;

[0058] Step 4. Carburizing the blank obtained in step 3 to obtain a carburized gear blank; the carburizing uses a nitrogen-methanol carburizing atmosphere...

Embodiment 3

[0067] This embodiment includes the following steps:

[0068] Step 1. Die forging the cylindrical steel raw material after heating to obtain a forged gear blank; the material of the cylindrical steel raw material is 18Cr2Ni4WA low-carbon alloy steel; the initial forging temperature in the die forging process is 1180°C, The temperature is 860°C;

[0069] Step 2: Perform normalizing and high-temperature tempering on the forging blank of the gear part obtained in step 1 in sequence to obtain a blank; the temperature of the normalizing is 950°C, and the temperature of the high-temperature tempering is 630°C;

[0070] Step 3: Carry out hobbing and contour processing on the blank obtained in step 2 to obtain a green body; during the hobbing and contour processing, a machining allowance is reserved at the spline; the reserved machining allowance at the spline satisfies : The thickness of the machining allowance is 2.9mm;

[0071] Step 4. Carburizing the blank obtained in step 3 to ...

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Abstract

The invention discloses a method for controlling the hardness of a spline after carburizing and integral quenching of a gear. The method comprises the following steps: 1 gear die forging; 2 normalizing and high-temperature tempering; 3 hobbing and contour processing; 4 carburizing; 5 high-temperature tempering; 6 turning and spline machining; 7 anti-carburizing coating protection; 8 quenching; 9 low-temperature tempering; and 10 finish machining. The allowance of the gear spline is designed before gear carburization, the problem that the hardness of the spline is improved after overall quenching due to the fact that the carbon content of a carburized layer transition area of the gear spline is increased is solved, the gear spline is protected by adopting an anti-carburizing coating before quenching, the situation that the surface layer of the spline is recarburized due to carburized gear atmosphere carbon potential protection is prevented, the problem that the surface hardness of the spline is high due to recarburization of the surface layer of the spline is solved, and the problem that the hardness of the spline is high due to the fact that chemical components of raw materials deviate from the upper limit is prevented by accurately controlling the tempering temperature through a local surface induction tempering treatment method after low-temperature tempering.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of low-carbon alloy steel, and in particular relates to a method for controlling spline hardness after carburizing and overall quenching of gears. Background technique [0002] Gear is a key part in the shearer transmission system, and the quality of the gear is crucial to the reliability of the shearer. In recent years, the heat treatment method of heavy-duty gears tends to be carburized and integrally quenched, and the carburizing, quenching and tempering, and surface quenching methods have the risk of insufficient quenching at the root and center of the tooth, resulting in insufficient contact fatigue strength and bending fatigue strength of the gear teeth. The problem of early failure of the gear is caused; but the overall quenching of the gear carburizing also has the problem of high spline hardness, which makes it difficult to guarantee product quality. [0003] The shortcomings of t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/32C21D1/28C21D1/18C23C8/22C23C8/04C21D1/42C21D11/00C23F17/00B23P15/14
CPCC21D9/32C21D1/28C21D1/18C23C8/22C23C8/04C21D1/42C21D11/00C23F17/00B23P15/14C21D2221/10C21D2261/00C21D2211/008Y02P10/25
Inventor 史仁贵朱科曾攀锦贺飞龙刘磊
Owner XIAN COAL MINING MACHINERY
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