Vacuum low-pressure carburizing process for shaft gear parts

A vacuum low-pressure carburizing and process technology, applied in metal material coating process, furnace type, manufacturing tools, etc., can solve problems such as large deformation of keyway and tooth shape, eliminate machining stress, improve surface carburizing effect, The effect of reducing the amount of deformation

Pending Publication Date: 2022-04-08

常州新区河海热处理工程有限公司

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AI-Extracted Technical Summary

Problems solved by technology

For high-precision shaft gear parts, the requirements for tooth profile accuracy are very high, such as figure 1 The tooth shape distortion of the shaft tooth parts shown is req...

Method used

A kind of shaft-tooth parts vacuum low-pressure carburizing process of the present invention adopts the mode of stepwise heating and heat preservation to heat up to the carburizing process temperature, which can eliminate the processing stress of shaft-tooth parts and reduce the stress of parts in the heating process. The amount of deformation, so that the carburizing deformation of the shaft and tooth parts reaches 0.005 ~ 0.015mm, which effectively solves the problem of tooth shape distortion caused by the carburizing process of the shaft and tooth parts; and, the vacuum low-pressure strong infiltration stage uses acetylene-nitrogen alternating pulses as the The carburizing atmosphere uses nitrogen to exhaust the waste gas generated in the furnace, which makes the control of the effective carburizing layer depth and surface carbon content more accurate, an...

Abstract

The invention discloses a vacuum low-pressure carburizing process for shaft gear parts, and belongs to the technical field of heat treatment. The vacuum low-pressure carburizing process for the shaft-gear parts sequentially comprises the temperature rising stage, the carburizing stage and the quenching stage, the temperature rises to the carburizing process temperature in a stepped temperature rising and heat preservation mode in the temperature rising stage, the machining stress of the shaft-gear parts can be eliminated, and the deformation amount of the parts in the heating process is reduced; the carburizing deformation of the shaft gear part reaches 0.005-0.015 mm, so that the problem of distortion generated in the carburizing process of the shaft gear part is effectively solved; moreover, in the vacuum low-pressure intense carburizing stage, acetylene-nitrogen alternating pulses are used as carburizing atmosphere, waste gas generated in the furnace is exhausted through nitrogen, the effective carburizing layer depth and the surface carbon content are controlled more accurately, and the shaft gear part surface carburizing effect is improved.

Application Domain

Solid state diffusion coatingFurnace types +1

Technology Topic

CarburizingHeat conservation +4

Image

Examples

Experimental program(3)

Example Embodiment

[0045] [Example 1]

[0046] by figure 1 The input shaft tooth part indicated by the display is an example. The material of the shaft tooth component is SCM420H alloy steel, and the heat treatment technology is required to: the effective hardened layer depth of the carbon layer (PCD 550HV) is 0.425 ~ 0.775mm, surface hardness It is 80.1 to 82.5hra, and the toothed distortion variable is 0.015 ~ 0.025mm.

[0047] In order to achieve the above heat treatment technique, an axial teeth component of the present embodiment, a vacuum low pressure depositary carburizing process, which sequentially includes a heating stage, a carburizing phase, and a quenching stage. In the heating stage, frame the workpiece and placed in the furnace. figure 2The stepped temperature rise heatup process, the inner vacuum is controlled below 1 Pa, and the workpiece is raised to 300 ± 5 ° C, 10 min; temperature above 480 ± 5 ° C, 10 min; heating to 680 ± 5 ° C, Water temperature was 20 min; heated to 780 ± 5 ° C, 10 min; heated to 850 ± 5 ° C, 10 min; heated to 960 ° C, reached the carbon-based process temperature, and entered the carbon stage. The specific carburizing process temperature can be determined according to the performance of the carburizing furnace. Through the above stepped temperature rise, the workpiece gradually increases to the carburizing process temperature, effectively eliminates the processing stress of the part, thereby reducing the amount of deformation in the heating process.

[0048] In the carburizing phase, including two stages of strong seepage and diffusion, a pulsed carburden process is used as a pulble-nitrogen alternating pulse, and the furnace pressure is controlled at 820 to 850Pa, alternately into acetylene gas. Nitrogen; specifically, after passing into acetylene gas for 2 seconds, it is re-entered into nitrogen for 5 seconds to a carburized pulse cycle, and the entire strong stage is composed of several carburized pulse cycles, and 5 carburized pulse cycles are used in this example. . The exhaust gas produced in the furnace is exhausted by nitrogen, enabling the effective carburizing layer depth and the surface-containing amount of carbon content to improve the surface of the shaft tooth partial partial carbon.

[0049] After completion of the strong stage, maintain the temperature of the carburizing process enters the diffusion stage, and the surface-carburized layer is formed after a period of time; after completion of the diffusion stage, the quenching stage can be used in vacuum high pressure gas quenching or oil quenching. Treatment, specifically, in the present embodiment, the quenching temperature of the quenching stage is 830 ± 5 ° C, which is quenched by a vacuum such as 135 ± 5 ° C, and at the same time, at a frequency of 15 Hz, it is low-speed, ensuring that the parts are uniform, reduce the parts. Deformation.

Example Embodiment

[0050] [Example 2]

[0051] The vacuum low pressure carbon carbon process of the insertion of the present embodiment is equally figure 1 A certain industrial robot replacement input shaft tooth part is an example, and its basic process flow is in the same embodiment, and the difference is:

[0052] In the heating stage, the vacuum in the furnace is controlled below 1pa, and the workpiece is raised to 300 ± 5 ° C, the temperature is 40min; temperature above 480 ± 5 ° C, 10 min; temperature above 40 min; temperature temperature Up to 780 ± 5 ° C, 10 min; heated to 850 ± 5 ° C, 10 min; heated to 960 ° C, reaching the carburizing process temperature, and entered the carbon stage.

[0053] In the carburizing stage, the furnace pressure is controlled at 820 to 850Pa, and the strong seam phase is introduced into acetylene gas for 20 seconds, and then the nitrogen gas is 40 seconds into a carburized pulse cycle, and the entire strong stage is composed of 5 carburized pulse cycles. The exhaust gas produced in the furnace was performed using nitrogen in the strong stage.

[0054] In the quenching stage, quenching is carried out in a conventional vacuum high pressure gas quenching.

Example Embodiment

[0055] [Example 3]

[0056] The vacuum low pressure carbon carbon process of the insertion of the present embodiment is equally figure 1 A certain industrial robot replacement input shaft tooth part is an example, and its basic process flow is in the same embodiment, and the difference is:

[0057] In the heating stage, the vacuum in the furnace is controlled below 1PA, and the workpiece is raised to 300 ± 5 ° C, the temperature is 10 min; the temperature is 10 min; temperature temperature to 680 ± 5 ° C, temperature temperature 30 min; temperature temperature Up to 780 ± 5 ° C, 10 min; heated to 850 ± 5 ° C, 10 min; heated to 950 ° C, reached the carbon-based process temperature, and entered the carbon stage.

[0058] In the carburizing stage, the furnace pressure is controlled at 850 to 880Pa, and the strong stage is introduced into acetylene gas for 10 seconds, then the nitrogen gas is 20 seconds into a carburized pulse cycle, and the entire strong stage is composed of 5 carburized pulse cycles. The exhaust gas produced in the furnace was performed using nitrogen in the strong stage.

[0059] In the quenching stage, a quenching treatment is made of a like temperature quenching oil.

[0060] A rival-ceramid of the present invention is a vacuum low pressure and low pressure carbon carbon process effectively solves the problem of distortion of the boxa process of the shaft clamping parts. See Table Table Experiment, the first set of data is a test data (atmosphere carburizing process reference patent No. ZL201610711836.1), and the second set of data is an embodiment of the present invention. 1 Test data after the vacuum low pressure carbon process treatment. The 9-point test method is used to sample the heat treated shaft tooth parts, and the specific sampling position see Figure 4 The orientation shown.

[0061]

[0062] Further, the existing atmosphere carburizing process penetration layer has a depth of 0.005 to 0.015 mm, and the surface of the present invention has no internal oxidation surface.

[0063] According to the above different process, it is understood that the toothed distortion of the part is obtained by the same effective hardened layer depth and surface hardness as the existing atmosphere of the carburizing process, and the surface hardness of the present invention. Smaller, lower than the lower limit of the technical requirements of the parts tooth distortion, and there is no internal oxidation on the surface of the permeability layer, and the surface of the shaft-clad part is carburized.

[0064] An axial teeth component of the present invention is vacuum low pressure carburizing process, and the method of warming up to the carburizing process in a step-incubation heat preservation, and the processing stress of the shaft-toothed part can be eliminated, and the amount of deformation of the part during heating is reduced. The amount of carburizing deformation of the shaft tooth is 0.005 ~ 0.015mm, which effectively solves the tooth distortion problem generated by the carburizing process of the shaft cladding part; and the vacuum low pressure strong seam stage is acetylene-nitrogen alternating pulse as a carburizing atmosphere The exhaust gas produced by nitrogen is exhausted by nitrogen, enabling the effective carbon-based layer depth and the surface-containing amount of carbon content to improve the surface of the shaft tooth part.

PUM

Property	Measurement	Unit
Surface hardness	80.1 ~ 82.5

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Small amount of deformation

Vacuum low-pressure carburizing process for shaft gear parts

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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