Carburizing and quenching process of wind power speed increasing gear

Abstract

The invention discloses a carburizing and quenching process of a wind power speed increasing gear, which belongs to the field of gear processing and comprises the following steps: 1) a first heating temperature equalizing stage; 2) a second heating temperature equalization stage; 3) a carburizing stage; 4) a diffusion stage; 5) a first cooling and temperature equalizing stage; 6) a second cooling and temperature equalizing stage; and (7) quenching. According to the carburizing and quenching process of the wind power speed increasing gear, the working procedures of heating and temperature uniformizing, carburizing, diffusing, cooling and temperature uniformizing, cooling and tempering are adopted, the depth of a carburizing layer is controlled, the carburizing quality is guaranteed, the tooth surface hardness and abrasion resistance are improved, residual stress is eliminated, and the service life of the gear is prolonged.

Description

Technical Field

[0001] The invention relates to a gear processing technology, and in particular to a carburizing and quenching technology for wind power speed increasing gears. Background Art

[0002] Wind energy is a renewable energy source. In recent years, wind power generation technology has experienced rapid development in market share, scale and technical design around the world. Wind power generation will become one of the main sources of electricity in the future. Wind power gearbox is one of the core components commonly used in wind power generation. It is mainly used to transmit the rotation of the wind wheel to the generator to make it run. However, due to the low speed of the wind wheel, it is usually necessary to rely on the gearbox to increase the speed. Gearbox components include planetary pins, planetary gears, sun gears, inner ring gears, torque arms / gearbox end covers, gearbox bodies, planet carriers, etc.

[0003] In order to make the gear parts obtain the comprehensive mechanical properties of hard outside and tough inside, the carburizing and quenching process is a relatively common heat treatment process method in the production process of heavy-duty gears. In the carburizing and quenching process, controlling the depth of the carburizing layer and ensuring the carburizing quality are important factors for the gears to obtain high hardness and high wear resistance. Therefore, it is a key issue to achieve high-quality development in the field of wind power gearboxes to propose a reasonable and effective carburizing and quenching process for large gears such as wind power gearboxes to improve their comprehensive performance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a carburizing and quenching process for a wind power speed increasing gear, which is used to solve the problem of increasing the thickness of the carburized layer and the residual stress.

[0005] The technical solution of the present invention is: a carburizing and quenching process for a wind power speed increasing gear, comprising the following steps:

[0006] 1) In the first heating and temperature-averaging stage, the wind power speed-increasing gear sample is placed in a carburizing furnace and heated to a first temperature-averaging temperature of 600±30°C, and the first temperature-averaging and temperature-averaging time is 100-150 minutes;

[0007] 2) In the second heating and temperature-averaging stage, the carburizing furnace is continued to be heated to a second temperature-averaging temperature of 810°C ± 20°C, and the second temperature-averaging and temperature-holding time is 150-240 minutes. A carburizing agent is introduced into the carburizing furnace for carburizing, and the carbon potential CP is controlled at 0.75C%;

[0008] 3) Carburizing stage: Continue to heat the carburizing furnace to the carburizing temperature, the carburizing temperature is 930±10℃, and introduce carburizing agent into the carburizing furnace for carburizing. The carbon potential CP is controlled at 1.15C%, and the carburizing time is maintained at t 渗碳 ;

[0009] 4) Diffusion stage: the diffusion temperature is the same as the carburizing temperature, which is 930±10℃. Carburizing agent is introduced into the carburizing furnace for carburizing. The carbon potential CP is controlled at 0.8C%, and the carburizing time is maintained at t 扩散 ;

[0010] 5) In the first cooling and averaging stage, the carburizing furnace temperature is lowered to the first cooling and averaging temperature, the first cooling and averaging temperature is 830±10°C, the first cooling and averaging time is about 300min, and the carbon potential CP is controlled at 0.85C%;

[0011] 6) In the second cooling and averaging stage, the carburizing furnace temperature is lowered from the first cooling and averaging temperature to the second cooling and averaging temperature, the second cooling and averaging temperature is 760±20° C., the second cooling and averaging time is about 200 min, and the carbon potential CP is controlled at 0.75C%;

[0012] 7) In the quenching stage, oil quenching is carried out, and the temperature is rapidly reduced from the second cooling average temperature to 20°C. The quenching time is about 10 minutes. After quenching, the gear sample is placed at room temperature.

[0013] Furthermore, the steel material for wind power speed increaser gears is 18CrNiMo7-6, which is suitable for making large and important carburized parts with high hardness, high strength and high toughness.

[0014] Furthermore, the dimensional parameters of the wind power speed increaser gear are: module 8.6, pressure angle 30°, number of teeth 138, helix angle 16.2°, displacement coefficient -0.25, pitch circle diameter of approximately 1235.87mm, top circle diameter of 1248.42mm, and root circle diameter of 1204mm.

[0015] Furthermore, the first temperature-averaging and heat-keeping time is 120 minutes.

[0016] Furthermore, the second temperature-averaging and heat-keeping time is 180 minutes.

[0017] Furthermore, the carburizing time t in the carburizing stage is 渗碳 About 540 minutes.

[0018] Furthermore, the diffusion time t in the diffusion stage 扩散 About 420 minutes.

[0019] Furthermore, after the quenching stage is completed, a low-temperature tempering stage is also included, the low-temperature tempering temperature is 200-300°C, and the tempering time is 100-150min.

[0020] Furthermore, the tempering time is 120 min.

[0021] Furthermore, the cooling rate in the first temperature-lowering and temperature-averaging stage is significantly lower than the cooling rate in the second temperature-lowering and temperature-averaging stage.

[0022] The beneficial technical effects of the present invention are:

[0023] The carburizing and quenching process of the wind power speed increasing gear proposed in the present invention adopts the procedures of heating to equalize temperature, carburizing, diffusion, cooling to equalize temperature, cooling and tempering to control the depth of the carburizing layer, ensure the carburizing quality, improve the hardness and wear resistance of the tooth surface, eliminate residual stress, and increase the service life of the gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the process route diagram of carburizing and quenching of the present invention;

[0025] Figure 2 It is the distribution diagram of the carburized layer thickness in the central section of the gear specimen after carburizing. DETAILED DESCRIPTION

[0026] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0027] See also Figure 1-2 This specific embodiment proposes a carburizing and quenching process for a wind power speed increasing gear, comprising the following steps:

[0028] 1) In the first heating and temperature-averaging stage, the wind power speed-increasing gear sample is placed in a carburizing furnace and heated to a first temperature-averaging temperature of 600±30° C. The first temperature-averaging and temperature-averaging time is 100-150 min, preferably 120 min;

[0029] 2) In the second heating and temperature-averaging stage, the carburizing furnace is continuously heated to a second temperature-averaging temperature of 810°C±20°C, and the second temperature-averaging and temperature-keeping time is 150-240 minutes, preferably 180 minutes. A carburizing agent is introduced into the carburizing furnace for carburizing, and the carbon potential CP is controlled at 0.75C%;

[0030] 3) Carburizing stage: Continue to heat the carburizing furnace to the carburizing temperature, the carburizing temperature is 930±10℃, and introduce carburizing agent into the carburizing furnace for carburizing. The carbon potential CP is controlled at 1.15C%, and the carburizing time is maintained at t 渗碳 ;

[0031] 4) Diffusion stage: the diffusion temperature is the same as the carburizing temperature, which is 930±10℃. Carburizing agent is introduced into the carburizing furnace for carburizing. The carbon potential CP is controlled at 0.8C%, and the carburizing time is maintained at t 扩散 ;

[0032] 5) In the first cooling and averaging stage, the carburizing furnace temperature is lowered to the first cooling and averaging temperature, the first cooling and averaging temperature is 830±10°C, the first cooling and averaging time is about 300min, and the carbon potential CP is controlled at 0.85C%;

[0033] 6) In the second cooling and averaging stage, the carburizing furnace temperature is lowered from the first cooling and averaging temperature to the second cooling and averaging temperature, the second cooling and averaging temperature is 760±20° C., the second cooling and averaging time is about 200 min, and the carbon potential CP is controlled at 0.75C%;

[0034] 7) In the quenching stage, oil quenching is carried out, and the temperature is rapidly reduced from the second cooling average temperature to 20°C. The quenching time is about 10 minutes. After quenching, the gear sample is placed at room temperature.

[0035] In this specific implementation, a first heating and temperature-averaging stage, a second heating and temperature-averaging stage, a first cooling and temperature-averaging stage, and a second cooling and temperature-averaging stage are specially set up. The step-by-step heating rate and cooling rate can effectively refine the grains and reduce the residual stress of the structure.

[0036] More specifically, the steel material for wind power speed increaser gears is 18CrNiMo7-6, which is suitable for making large and important carburized parts with high hardness, high strength and high toughness.

[0037] More specifically, the dimensional parameters of the wind power speed increaser gear are: module 8.6, pressure angle 30°, number of teeth 138, helix angle 16.2°, displacement coefficient -0.25, pitch circle diameter of approximately 1235.87mm, top circle diameter of 1248.42mm, and root circle diameter of 1204mm.

[0038] In this specific embodiment, the composition of 18CrNiMo7-6 is as shown in Table 1:

[0039] Table 118 Chemical composition of CrNiMo7-6 steel

[0040]

[0041] More specifically, the carburizing time t in the carburizing stage is 渗碳 About 540 minutes.

[0042] More specifically, the diffusion time t in the diffusion stage 扩散 About 420 minutes.

[0043] More specifically, after the quenching stage is completed, a low-temperature tempering stage is also included. The temperature of the low-temperature tempering is 200-300° C., and the tempering time is 100-150 minutes, preferably 120 minutes.

[0044] In this specific embodiment, after the carburizing and diffusion stage is completed, a first cooling and averaging stage and a second cooling and averaging stage are specially set. The cooling rate of the first cooling and averaging stage is significantly lower than the cooling rate of the second cooling and averaging stage. Figure 1 As shown in the middle line segments A and B, the cooling rate of line segment A is about one-third of that of line segment B. Combined with the final quenching process line segment C, it can be seen that the cooling rates of line segments A, B, and C in the carburizing furnace increase in a step-by-step manner, avoiding the residual stress problem caused by the excessively fast oil quenching cooling rate directly after the carburizing diffusion stage, and the residual stress problem of the gear is significantly improved.

[0045] The carburizing and quenching process of the wind power speed increase gear in this specific embodiment adopts the processes of heating and temperature equalization, carburizing, diffusion, cooling and temperature equalization, quenching, tempering, etc., which effectively eliminates the residual stress of the wind power speed increase gear, obtains dispersed fine-grained carbides, improves the hardness and wear resistance of the tooth surface, and increases the service life of the gear. Another invention, this specific embodiment performs a low-magnification test on the microstructure of the thick end section of the gear sample, and the results are as follows Figure 2 Through image processing, the carburized layer thickness from the surface to the core of the sample was measured to be 1.59mm, 1.81mm, 1.68mm and 1.81mm respectively, and the average carburized layer thickness was 1.72mm, indicating that the process route achieved a better carburized layer thickness and had strong commercial application value.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. The carburizing and quenching process of wind power speed increasing gear is characterized by: The following steps are involved: 1) In the first heating and temperature-averaging stage, the wind power speed-increasing gear sample is placed in a carburizing furnace and heated to a first temperature-averaging temperature of 600±30°C, and the first temperature-averaging and temperature-averaging time is 100-150 minutes; 2) In the second heating and temperature-averaging stage, the carburizing furnace is continued to be heated to a second temperature-averaging temperature of 810°C ± 20°C, and the second temperature-averaging and temperature-holding time is 150-240 minutes. A carburizing agent is introduced into the carburizing furnace for carburizing, and the carbon potential CP is controlled at 0.75C%; 3) Carburizing stage: Continue to heat the carburizing furnace to the carburizing temperature, the carburizing temperature is 930±10℃, and introduce carburizing agent into the carburizing furnace for carburizing. The carbon potential CP is controlled at 1.15C%, and the carburizing time is maintained at t 渗碳 ; 4) Diffusion stage: the diffusion temperature is the same as the carburizing temperature, which is 930±10℃. Carburizing agent is introduced into the carburizing furnace for carburizing. The carbon potential CP is controlled at 0.8C%, and the carburizing time is maintained at t 扩散 ; 5) In the first cooling and averaging stage, the carburizing furnace temperature is lowered to the first cooling and averaging temperature, the first cooling and averaging temperature is 830±10°C, the first cooling and averaging time is about 300min, and the carbon potential CP is controlled at 0.85C%; 6) In the second cooling and averaging stage, the carburizing furnace temperature is lowered from the first cooling and averaging temperature to the second cooling and averaging temperature, the second cooling and averaging temperature is 760±20° C., the second cooling and averaging time is about 200 min, and the carbon potential CP is controlled at 0.75C%; 7) In the quenching stage, oil quenching is carried out, and the temperature is rapidly reduced from the second cooling average temperature to 20°C. The quenching time is about 10 minutes. After quenching, the gear sample is placed at room temperature.

2. The carburizing and quenching process of the wind power speed increasing gear according to claim 1 is characterized in that: The steel material used for wind power speed increase gear is 18CrNiMo7-6.

3. The carburizing and quenching process of the wind power speed increasing gear according to claim 1 is characterized in that: The dimensional parameters of the wind power speed increaser gear are: module is about 8.6, pressure angle is about 30°, number of teeth is about 138, helix angle is about 16.2°, displacement coefficient is about -0.25, pitch circle diameter is about 1235.87mm, tooth top circle diameter is about 1248.42mm, and tooth root circle diameter is about 1204mm.

4. The carburizing and quenching process of the wind power speed increasing gear according to claim 1 is characterized in that: The first temperature-averaging and heat-keeping time is 120 minutes.

5. The carburizing and quenching process of the wind power speed increasing gear according to claim 1, characterized in that: The second temperature-averaging and heat-keeping time is 180 minutes.

6. The carburizing and quenching process of the wind power speed increasing gear according to claim 1, characterized in that: The carburizing time t in the carburizing stage 渗碳 About 540 minutes.

7. The carburizing and quenching process for wind power speed increasing gear according to claim 1, characterized in that: The diffusion time t in the diffusion stage 扩散 About 420 minutes.

8. The carburizing and quenching process for wind power speed increasing gear according to claim 1, characterized in that: After the quenching stage is completed, it also includes a low-temperature tempering stage. The temperature of the low-temperature tempering is 200-300°C and the tempering time is 100-150 minutes.

9. The carburizing and quenching process for wind power speed increasing gear according to claim 8, characterized in that: The tempering time is 120 minutes.

10. The carburizing and quenching process of the wind power speed increasing gear according to claim 1, characterized in that: The cooling rate in the first temperature-dropping and temperature-averaging stage is significantly lower than the cooling rate in the second temperature-dropping and temperature-averaging stage.

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