Vacuum carburizing method for guide rail sliding block

Abstract

The invention discloses a vacuum carburizing method for a guide rail sliding block. The method comprises the following steps that firstly, a sliding block is preheated; then the preheated sliding block is subjected to vacuum carburizing treatment; carrying out slow cooling and quenching on the slide block subjected to vacuum carburizing treatment; then, the sliding block is subjected to low-temperature tempering; and finally, carrying out effective hardened layer depth measurement and metallographic detection on the slide block subjected to heat treatment. By means of the vacuum carburizing method, the heat treatment efficiency of the sliding block can be improved, the surface hardness of the sliding block can reach 740-750 HV and is evenly distributed, the effective hardened layer depth can reach 1.0 mm, the abrasion resistance and the fatigue resistance of the sliding block are improved, and the excellent toughness and strength of the core of the sliding block are kept.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of heat treatment of metals, and particularly relates to a vacuum carburizing method for guide rail sliders. BACKGROUND

[0002] Sliders are widely used in high-end CNC machine tools, precision instruments, hydraulic systems and other fields as part of a guide rail pair. In actual use, the slider needs to be reciprocated for a long time and bear alternating loads, which leads to failure of the slider. Therefore, the slider needs to have high hardness, high wear resistance and fatigue resistance through heat treatment to improve the service life of the slider.

[0003] Currently, the most important heat treatment method for sliders is carburizing and quenching, but the existing carburizing and quenching process has the following problems: the slider surface is easily eroded by oxidizing media, forming a carburized layer with many pores, which reduces the surface strength of the slider; the slider surface is prone to have many carburizing bodies, which increases the brittleness of the slider surface and reduces the strength; the hardness and structure of the slider surface are uneven, which leads to poor fatigue resistance of the slider. SUMMARY

[0004] In order to solve the problems in the background art, the purpose of the present application is to provide a vacuum carburizing method for guide rail sliders to improve the wear resistance and fatigue resistance of the sliders and prolong their service life.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: S1: preheating the slider; S2: vacuum carburizing the preheated slider; S3: slow cooling and quenching the slider after S2; S4: low-temperature tempering the slider after S3; S5: post-treatment inspection of the slider after S4.

[0006] The S1 specifically includes: Put the slider into the carburizing furnace, set the vacuum degree in the carburizing furnace to be 1x10 -2 Pa or below, increase the temperature in the furnace from 700~800℃ to 920~940℃ at a speed of 4~8℃ / min, and keep the temperature for 60~70min.

[0007] In the S2, the temperature in the carburizing furnace is kept at 920~940℃, acetylene is introduced into the carburizing furnace at a flow rate of 40~45L / min, the introduction is stopped after 60~70min and the diffusion stage is entered, the furnace temperature is maintained at 920~940℃, the diffusion time is 70~80min, and the vacuum degree in the furnace is kept within 100Pa during the whole diffusion process.

[0008] In step S3, the slider is cooled in the furnace to 840~850℃ and held for 60~70 minutes. Then, the slider is quickly quenched in oil and cooled by stirring and circulating. The oil temperature is 120℃ or 80℃ and the quenching time is 30~40 minutes.

[0009] In step S4, the slide tempering temperature is 170~175℃, and the tempering time is 120~130min.

[0010] The post-processing inspection includes measurement of the effective hardened layer depth and metallographic examination.

[0011] The measurement of the effective hardened layer depth includes: The hardness is measured from the surface of the slider that is in contact with the rolling element into the slider. When the hardness drops to 550 HV, the distance from that position to the slider surface is measured and recorded as the depth of the effective hardened layer.

[0012] The metallographic testing includes: Metallographic analysis was performed on the surface and core microstructure of the slider.

[0013] Compared with existing technologies, the beneficial effects of the present invention are as follows: By controlling the vacuum level in the furnace before carburizing, impurity gases can be effectively removed, significantly reducing surface oxidation and decarburization of the slider during the carburizing process. The vacuum carburizing process for sliders used in this invention shortens the process time compared to existing carburizing processes, improves the heat treatment efficiency of the slider, and forms a high-hardness and uniformly structured reinforcing layer on the slider surface. This improves the surface hardness uniformity of the slider, achieving a surface hardness of over 700 HV and a hardened layer thickness of up to 1 mm. Furthermore, the slider core maintains excellent toughness and strength, significantly improving the slider's fatigue resistance. Attached Figure Description

[0014] Figure 1 This is a line graph showing the change in hardness of the contact area between the slider and the rolling element as a function of depth in Example 1. Figure 2 The phase diagram of the surface microstructure of the slider in Example 1; Figure 3 The phase diagram of the slider core structure in Example 1; Figure 4 This is a line graph showing the change in hardness of the contact area between the slider and the rolling element as a function of depth in Example 2. Figure 5 The phase diagram of the surface microstructure of the slider in Example 2; Figure 6 This is a phase diagram of the slider core structure in Example 2. Detailed Implementation

[0015] The present invention will be further described below with reference to the embodiments.

[0016] It should be noted that the slider material in this embodiment of the invention is low-carbon alloy steel 20CrMoH.

[0017] Example 1.

[0018] A vacuum carburizing method for guide rail sliders is implemented as follows: S1: Place the slider into the carburizing furnace and set the vacuum level inside the furnace to 1×10⁻⁶. -2 Pa can effectively remove impurity gases and reduce the formation of an oxidized and decarburized layer on the surface of the slider. The furnace temperature is increased from 800℃ to 930℃ at a rate of 5℃ / min and then homogenized for 60 min to ensure that the temperature inside and outside the slider is consistent and reaches above the austenitizing temperature.

[0019] S2: Vacuum carburizing treatment is performed on the slider. The temperature inside the carburizing furnace is maintained at 930℃. Acetylene is introduced into the carburizing furnace at a flow rate of 42 L / min and continued for 60 min before stopping and entering the diffusion stage. The furnace temperature is maintained at 930℃ and the diffusion time is 74 min. Throughout the diffusion process, the vacuum degree inside the furnace is maintained below 100 Pa, and the carbon potential CP is controlled at around 0.9%, which can make the carburized layer have a good concentration distribution and uniform structure.

[0020] S3: Slowly cool and quench the slider. The slider is cooled to 840℃ in the furnace and held for 60 min. Then, the slider is quickly quenched in oil with stirring and circulation cooling. The oil temperature is 120℃ and the quenching time is 35 min to allow the slider to cool fully and obtain a uniform martensitic structure on the surface.

[0021] S4: Perform low-temperature tempering on the slider at a temperature of 170℃ for 120 min to stabilize the microstructure.

[0022] S5: Measure the effective hardened layer depth and perform metallographic inspection on the heat-treated slider. Start measuring the hardness from the surface where the slider and rolling element contact each other and move towards the inside of the slider. When the hardness drops to 550 HV, measure the distance from that position to the slider surface, which is the effective hardened layer depth. Perform metallographic inspection on the surface and core structures of the slider.

[0023] After being treated by the vacuum carburizing process of this invention, such as Figure 1 As shown, the hardness of the contact surface between the slider and the rolling element reaches 750 HV, and the effective hardened layer depth, that is, the surface layer thickness with a hardness of 550 HV or above, is about 1 mm and is evenly distributed. Figure 2 The phase diagram of the slider surface microstructure in this embodiment of the invention shows that it is composed of fine high-carbon martensite, which can significantly improve the slider's hardness and wear resistance. Figure 3The phase diagram of the slider core in this embodiment of the invention is mainly composed of tempered sorbite and ferrite, which has excellent comprehensive mechanical properties, enabling the slider core to maintain excellent toughness and strength, and improving the overall fatigue resistance and impact resistance of the slider.

[0024] Example 2.

[0025] A vacuum carburizing method for guide rail sliders is implemented as follows: S1: Place the slider into the carburizing furnace and set the vacuum level inside the furnace to 1×10⁻⁶. -2 Pa can effectively remove impurity gases and reduce the formation of an oxidized and decarburized layer on the surface of the slider. The furnace temperature is increased from 800℃ to 930℃ at a rate of 5℃ / min and then homogenized for 60 min to ensure that the temperature inside and outside the slider is consistent and reaches above the austenitizing temperature.

[0026] S2: Vacuum carburizing treatment is performed on the slider. The temperature inside the carburizing furnace is maintained at 930℃. Acetylene is introduced into the carburizing furnace at a flow rate of 42 L / min and continued for 60 min before stopping and entering the diffusion stage. The furnace temperature is maintained at 930℃ and the diffusion time is 74 min. Throughout the diffusion process, the vacuum degree inside the furnace is maintained below 100 Pa, and the carbon potential CP is controlled at around 0.9%, which can make the carburized layer have a good concentration distribution and uniform structure.

[0027] S3: Slowly cool and quench the slider. The slider is cooled to 840℃ in the furnace and held for 60 min. Then, the slider is quickly quenched in oil with stirring and circulation cooling. The oil temperature is 80℃ and the quenching time is 35 min to allow the slider to cool fully and obtain a uniform martensitic structure on the surface.

[0028] S4: Perform low-temperature tempering on the slider at a temperature of 170℃ for 120 min to stabilize the microstructure.

[0029] S5: Measure the effective hardened layer depth and perform metallographic inspection on the heat-treated slider. Start measuring the hardness from the surface where the slider and rolling element contact each other and move towards the inside of the slider. When the hardness drops to 550 HV, measure the distance from that position to the slider surface, which is the effective hardened layer depth. Perform metallographic inspection on the surface and core structures of the slider.

[0030] After being treated by the vacuum carburizing process of this invention, such as Figure 4 As shown, the hardness of the contact surface between the slider and the rolling element reaches 740 HV, and the effective hardened layer depth, that is, the surface layer thickness with a hardness of 550 HV or above, is 0.8 ~ 0.9 mm, and is evenly distributed. Figure 5 The phase diagram of the slider surface microstructure in this embodiment of the invention shows that it is composed of fine high-carbon martensite, which can significantly improve the slider's hardness and wear resistance. Figure 6The phase diagram of the slider core in this embodiment of the invention is mainly composed of tempered sorbite and ferrite, which has excellent comprehensive mechanical properties, enabling the slider core to maintain excellent toughness and strength, and improving the overall fatigue resistance and impact resistance of the slider.

[0031] Finally, it should be noted that the above embodiments and descriptions are only used to illustrate the technical solutions of the present invention and not to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the disclosure of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the protection scope of the claims of the present invention.

Claims

1. A vacuum carburizing method for a guide rail slider, characterized in that, Includes the following steps: S1: Preheat the slider; S2: Vacuum carburizing treatment is performed on the preheated slider; S3: Slow cooling and quenching of the slider after S2 treatment; S4: Perform low-temperature tempering on the slider after S3 treatment; S5: Perform post-processing checks on the slider after processing in S4.

2. The vacuum carburizing method for a guide rail slider according to claim 1, characterized in that, S1 specifically includes: Place the slider into the carburizing furnace and set the vacuum level inside the furnace to 1×10⁻⁶. -2 For Pa and below, the furnace temperature is increased from 700~800℃ to 920~940℃ at a rate of 4~8℃ / min, and then homogenized for 60~70min.

3. The vacuum carburizing method for a guide rail slider according to claim 1, characterized in that, In step S2, the temperature inside the carburizing furnace is maintained at 920~940℃. Acetylene is introduced into the carburizing furnace at a flow rate of 40~45L / min and is continuously introduced for 60~70min before stopping and entering the diffusion stage. The furnace temperature is maintained at 920~940℃ and the diffusion time is 70~80min. The vacuum degree inside the furnace is maintained below 100Pa throughout the diffusion process.

4. The vacuum carburizing method for a guide rail slider according to claim 1, characterized in that, In step S3, the slider is cooled to 840~850℃ in the furnace and held for 60~70 minutes. Then, the slider is quenched in oil and cooled by stirring and circulating. The oil temperature is 120℃ or 80℃ and the quenching time is 30~40 minutes.

5. The vacuum carburizing method for a guide rail slider according to claim 1, characterized in that, In step S4, the slide tempering temperature is 170~175℃, and the tempering time is 120~130min.

6. The vacuum carburizing method for a guide rail slider according to claim 1, characterized in that, The post-processing inspection includes measurement of the effective hardened layer depth and metallographic examination.

7. The vacuum carburizing method for a guide rail slider according to claim 6, characterized in that, The measurement of the effective hardened layer depth includes: The hardness is measured from the surface of the slider that is in contact with the rolling element into the slider. When the hardness drops to 550 HV, the distance from that position to the slider surface is measured and recorded as the depth of the effective hardened layer.

8. The vacuum carburizing method for a guide rail slider according to claim 6, characterized in that, The metallographic testing includes: Metallographic analysis was performed on the surface and core microstructure of the slider.

Images