Manufacturing method of high-air-tightness and high-wear-resistance powder metallurgy component

Abstract

The invention discloses a manufacturing method of a high-air-tightness and high-wear-resistance powder metallurgy part. The manufacturing method comprises the following steps of compression molding, wherein powder is subjected to compression molding to obtain a powder metallurgy part blank; sintering: sintering the powder metallurgy part blank in shielding gas through heating and heat preservation; water vapor treatment is conducted, specifically, the powder metallurgy part blank is placed in a heating furnace, supersaturated water vapor is introduced into the heating furnace so that the supersaturated water vapor and the powder metallurgy part blank can be subjected to a chemical reaction, and dense imgabs0 # is generated on the surface and pores of the powder metallurgy part blank; and liquid nitriding is conducted, specifically, the powder metallurgy part blank is soaked in a salt bath to be subjected to salt bath nitriding, the nitriding time ranges from 3.5 h to 4.5 h, and the nitriding temperature ranges from 560 DEG C to 570 DEG C. According to the manufacturing method of the high-air-tightness and high-wear-resistance powder metallurgy part, the air tightness of an upper floating plate of the powder metallurgy part can be guaranteed, meanwhile, the surface hardness of the powder metallurgy part is improved to 500 HV0.2 or above, wear of the small end face of the upper floating plate of the powder metallurgy part is reduced, and the quality of a compressor is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance. Background Art

[0002] The function of the air-conditioning scroll compressor is to compress the refrigerant, increase its pressure and temperature, so that it can transfer and transmit heat in the air-conditioning system, thereby achieving the purpose of cooling or heating.

[0003] The floating plate is an important component of the scroll compressor. Its function is to adjust the compression ratio: by adjusting the volume of the compression chamber, the compression ratio can be controlled to adapt to different refrigeration load requirements.

[0004] When the compressor is working, the small end surface of the upper floating plate will have micro-wear with the sealing plate, wherein the hardness of the sealing plate is 500HV0.2.

[0005] However, the existing powder metallurgy floating plate can meet the airtightness requirements after being treated with water vapor, but the hardness only reaches 150HV0.2-200HV0.2, and the small end surface of the floating plate is severely worn, which directly affects the quality of the compressor. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance, which can ensure the air tightness of the upper floating plate of the powder metallurgy part while increasing the surface hardness of the powder metallurgy part to above 500HV0.2, reduce the wear of the small end surface of the upper floating plate of the powder metallurgy part, and ensure the quality of the compressor.

[0007] A method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention comprises the following steps: Pressing and molding: Use a mold to press the pre-mixed powder into a powder metallurgy blank; Sintering: The powder metallurgy blank obtained in the pressing step is sintered by heating and heat preservation in a protective gas; Steam treatment: The sintered powder metallurgy blank is placed in a heating furnace, and supersaturated steam is introduced into the heating furnace to allow the supersaturated steam to react chemically with the powder metallurgy blank and form a dense surface and pores of the powder metallurgy blank. ; Liquid nitriding: The powder metallurgy blank after water vapor treatment is immersed in a salt bath for salt bath nitriding. The nitriding time is 3.5h-4.5h and the nitriding temperature is 560℃-570℃.

[0008] A method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention has at least the following beneficial effects: 1. The present invention provides a pressing step, in which a mold is used to press and mold the pre-mixed powder to obtain a powder metallurgy blank, thereby facilitating the manufacture of the powdery raw material into the shape of a product.

[0009] 2. The present invention provides a sintering step, in which the powder metallurgy blank obtained in the pressing step is sintered in a protective gas by heating and heat preservation, so that during the sintering process, the bonding force between the powder particles is enhanced, so that the pressed powder metallurgy blank forms a solid metal body.

[0010] 3. The present invention provides a steam treatment step, in which the sintered powder metallurgy blank is placed in a heating furnace, and supersaturated steam is introduced into the heating furnace to allow the supersaturated steam to react chemically with the powder metallurgy blank and form a dense , thereby improving the air tightness and hardness of the powder metallurgy blank.

[0011] 4. The present invention provides a liquid nitriding step, in which the powder metallurgy blank treated with water vapor is immersed in a salt bath for salt bath nitriding, the nitriding time is 3.5h-4.5h, and the nitriding temperature is 560℃-570℃. It can be understood that by subjecting the powder metallurgy blank to salt bath nitriding, a nitriding compound layer with a thickness of more than 0.05mm can be formed on the surface of the powder metallurgy blank, thereby improving the surface hardness of the powder metallurgy blank, so that the surface hardness of the powder metallurgy blank reaches more than 500HV0.2. At the same time, the medium of the salt bath nitriding is liquid, which cannot penetrate into the core of the powder metallurgy blank, so that the salt bath nitriding will not destroy the dense layer formed in the core of the powder metallurgy blank in the water vapor treatment step. , ensuring the airtightness of the powder metallurgy blank, thereby ensuring the airtightness of the powder metallurgy upper floating plate while increasing the surface hardness of the powder metallurgy part to above 500HV0.2, reducing the wear of the small end face of the powder metallurgy upper floating plate and ensuring the quality of the compressor.

[0012] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, the nitriding time is 4 hours.

[0013] Advantageously, the present invention sets the nitriding time to 4 hours, thereby ensuring the nitriding quality of the powder metallurgy blank in the salt bath nitriding.

[0014] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance in an embodiment of the present invention, the liquid nitriding step also includes a preheating step, which is arranged before the salt bath nitriding. In the preheating step, the powder metallurgy part blank is placed on a tooling and preheated to 400°C.

[0015] Advantageously, the present invention provides a preheating step in the liquid nitriding step, which is provided before the salt bath nitriding. In the preheating step, the powder metallurgy blank is placed on a tooling and preheated to 400° C., so that the body temperature of the powder metallurgy blank when placed in the salt bath can be close to the temperature of the salt bath, thereby avoiding the nitriding quality of the powder metallurgy blank being affected by the sudden change in temperature when the powder metallurgy blank is immersed in the salt bath.

[0016] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, the liquid nitriding step also includes a water cooling step, a cleaning step and a drying step performed in sequence, and the water cooling step, the cleaning step and the drying step are performed after the salt bath nitriding.

[0017] Advantageously, the present invention provides a water cooling step, a cleaning step and a drying step in the liquid nitriding step, and the water cooling step, the cleaning step and the drying step are performed after the salt bath nitriding, thereby facilitating cooling of the powder metallurgy blank after the salt bath nitriding, and at the same time, cleaning and removing the dirt remaining on the surface of the powder metallurgy blank in the salt bath nitriding, and drying the cleaned powder metallurgy blank for the next step.

[0018] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, the drying step dries the powder metallurgy part blank at 400° C. for 2 hours.

[0019] Advantageously, the present invention dries the powder metallurgy blank at 400° C. for 2 hours in the drying step, thereby ensuring that the powder metallurgy blank can be fully dried and avoiding residual moisture from affecting the next process.

[0020] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, the liquid nitriding step also includes a sandblasting step, which is arranged after the drying step, and the sandblasting step sandblasts the surface of the powder metallurgy part blank.

[0021] Advantageously, the present invention provides a sandblasting step in the liquid nitriding step, and the sandblasting step is provided after the drying step. The sandblasting step sandblasts the surface of the powder metallurgy blank, so that the sandblasting can further remove and clean the attachments on the surface of the powder metallurgy blank, thereby making the surface of the powder metallurgy blank cleaner.

[0022] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, a cleaning step is further provided after the liquid nitriding step, and the cleaning step is used to clean the dirt on the surface of the powder metallurgy part blank after the nitriding treatment.

[0023] Advantageously, the present invention further provides a cleaning step after the liquid nitriding step, and the cleaning step is used to clean the dirt on the surface of the powder metallurgy blank after the nitriding treatment, thereby facilitating the removal of sand and dirt remaining on the surface of the powder metallurgy blank during the sandblasting process, thereby ensuring that the surface of the powder metallurgy blank is clean.

[0024] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, an inspection step is further provided after the cleaning step, and the inspection step performs dimensional inspection and appearance inspection on the powder metallurgy part.

[0025] Advantageously, the present invention further provides an inspection step after the cleaning step, wherein the inspection step performs dimensional inspection and appearance inspection on the powder metallurgy parts, thereby facilitating monitoring of the size and appearance of the powder metallurgy parts and preventing the outflow of defective dimensional and appearance products.

[0026] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, an oil immersion step is further provided after the inspection step, and the oil immersion step performs oil immersion on the powder metallurgy part to prevent rust.

[0027] Advantageously, the present invention further provides an oil immersion step after the inspection step, in which the powder metallurgy parts are immersed in oil for rust prevention, thereby preventing the powder metallurgy parts from rusting.

[0028] According to a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention, the sintering holding temperature of the sintering step is , the holding time is .

[0029] Advantageously, the present invention sets the sintering holding temperature of the sintering step to , the holding time is set to , so that the sintering temperature can reach about 80% of the melting point of the main component iron of the powder, thereby meeting the requirements of the sintering temperature and sintering insulation time of the powder metallurgy blank.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic structural diagram of a powder metallurgy part manufactured by a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention; Figure 2 This is a process flow chart of a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention; Figure 3 for Figure 2 A flow chart showing the steps of liquid nitriding; Figure 4 The metallographic diagram of a powder metallurgy part manufactured by a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention.

[0033] Reference numerals: 100 - annular base plate, 110 - convex ring, 120 - small end face. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0035] In the description of the present invention, it is necessary to understand that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of first and second, this is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation, connection and connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] A method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention will be described below in conjunction with the accompanying drawings.

[0039] The present invention aims to provide an embodiment of a method for manufacturing a powder metallurgy part with high air tightness and high wear resistance.

[0040] Reference Figure 1 In this embodiment, a method for manufacturing a high-airtightness and high-wear-resistant powder metallurgy part is used to manufacture an upper floating plate of a scroll compressor. Specifically, the upper floating plate is in a circular ring shape, and the upper floating plate includes an annular bottom plate 100 and a convex ring 110 arranged on the top surface of the annular bottom plate 100. The end of the convex ring 110 away from the annular bottom plate 100 is a small end face 120 of the upper floating plate. When the scroll compressor is working, the small end face 120 of the upper floating plate will have micro-friction with the sealing plate, wherein the hardness of the sealing plate is 500HV0.2.

[0041] Reference Figure 2 A method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to an embodiment of the present invention comprises the following steps: Pressing: Use a mold to press the pre-mixed powder into a powder metallurgy blank.

[0042] This embodiment provides a pressing step, in which a mold is used to press and mold the pre-mixed powder to obtain a powder metallurgy blank, thereby facilitating the manufacture of the powdery raw material into the shape of a product.

[0043] Sintering: The powder metallurgy blank obtained in the pressing step is sintered by heating and heat preservation in a protective gas.

[0044] In this embodiment, a sintering step is provided, in which the powder metallurgy blank obtained in the pressing step is sintered in a protective gas by heating and heat preservation. Thus, during the sintering process, the bonding force between the powder particles is enhanced, so that the pressed powder metallurgy blank forms a solid metal body.

[0045] In some specific embodiments, the sintering holding temperature of the sintering step is , the holding time is .

[0046] In this embodiment, the sintering temperature in the sintering step is set to , the holding time is set to , so that the sintering temperature can reach about 80% of the melting point of the main component iron of the powder, thereby meeting the requirements of the sintering temperature and sintering insulation time of the powder metallurgy blank.

[0047] Rough turning: The rough turning step is to perform rough turning on the sintered powder metallurgy blank according to the processing size requirements.

[0048] In this embodiment, the powder metallurgy blank is rough-turned after the sintering step and before the steam treatment step. It can be understood that the hardness of the powder metallurgy blank after sintering can be initially improved to HRB65 or above, so that the structure of the powder metallurgy blank has a certain strength, which can prevent the powder metallurgy blank from being broken by the cutting force of the tool during rough turning. In addition, since the rough turning process has a large processing volume, performing rough turning before the steam treatment step can reduce the difficulty of rough turning.

[0049] Steam treatment: The sintered powder metallurgy blank is placed in a heating furnace, and supersaturated steam is introduced into the heating furnace to allow the supersaturated steam to react chemically with the powder metallurgy blank and form a dense surface and pores of the powder metallurgy blank. .

[0050] In this embodiment, a steam treatment step is provided. In the steam treatment step, the sintered powder metallurgy blank is placed in a heating furnace, and supersaturated steam is introduced into the heating furnace so that the supersaturated steam reacts chemically with the powder metallurgy blank and forms a dense , thereby improving the air tightness and hardness of the powder metallurgy blank.

[0051] Finishing machining: The finishing machining step is to perform finishing machining on the powder metallurgy blank after water vapor treatment according to the machining size.

[0052] In this embodiment, the powder metallurgy blank is subjected to finish turning after the steam treatment step. It can be understood that the hardness of the powder metallurgy blank after the steam treatment can be further improved to reach HRB85 or above, thereby reducing the risk of material breakage in the powder metallurgy blank during finish turning, and further improving the processing progress of the finish turning.

[0053] In addition, since the roughness of the small end surface 120 of the powder metallurgy blank after the steam treatment does not meet the requirement of less than Ra1.6, the roughness of the small end surface 120 of the powder metallurgy blank can be guaranteed by performing the finishing after the steam treatment.

[0054] Liquid nitriding: The powder metallurgy blank after water vapor treatment is immersed in a salt bath for salt bath nitriding. The nitriding time is 3.5h-4.5h and the nitriding temperature is 560℃-570℃.

[0055] It can be understood that by subjecting the powder metallurgy blank to salt bath nitriding treatment, a nitriding compound layer with a thickness of more than 0.05 mm can be formed on the surface of the powder metallurgy blank, thereby improving the surface hardness of the powder metallurgy blank, so that the surface hardness of the powder metallurgy blank reaches more than 500HV0.2. At the same time, the medium of salt bath nitriding is liquid and cannot penetrate into the core of the powder metallurgy blank, so that the salt bath nitriding will not destroy the dense layer formed in the core of the powder metallurgy blank in the steam treatment step. , ensuring the air tightness of the powder metallurgy blank, thereby ensuring the air tightness of the powder metallurgy upper floating plate while increasing the surface hardness of the powder metallurgy part to above 500HV0.2, reducing the wear of the small end face 120 of the powder metallurgy upper floating plate and ensuring the quality of the compressor.

[0056] Specifically, the nitriding time is 4 hours.

[0057] In this embodiment, the nitriding time is set to 4 hours, thereby ensuring the nitriding quality of the powder metallurgy blank in the salt bath nitriding.

[0058] Reference Figure 3 In some specific embodiments, the liquid nitriding step further includes a preheating step, which is arranged before the salt bath nitriding. In the preheating step, the powder metallurgy blank is placed on the tooling for preheating to 400° C., so that the body temperature of the powder metallurgy blank when placed in the salt bath can be close to the temperature of the salt bath, thereby avoiding the nitriding quality of the powder metallurgy blank being affected by the sudden change of temperature when the powder metallurgy blank is immersed in the salt bath.

[0059] In some specific embodiments, the liquid nitriding step also includes a water cooling step, a cleaning step and a drying step which are performed in sequence. The water cooling step, the cleaning step and the drying step are performed after the salt bath nitriding, thereby facilitating cooling of the powder metallurgy blank after the salt bath nitriding, and cleaning and removing the dirt remaining on the surface of the powder metallurgy blank during the salt bath nitriding, and drying the cleaned powder metallurgy blank for the next step.

[0060] Specifically, the drying step dries the powder metallurgy blank at 400° C. for 2 hours, thereby ensuring that the powder metallurgy blank can be fully dried to avoid residual moisture affecting the next process.

[0061] In some specific embodiments, the liquid nitriding step also includes a sandblasting step, which is arranged after the drying step. The sandblasting step sandblasts the surface of the powder metallurgy blank, so that the sandblasting can further remove and clean the attachments on the surface of the powder metallurgy blank, thereby making the surface of the powder metallurgy blank cleaner.

[0062] Cleaning: The cleaning step uses a high-pressure spray machine and an ultrasonic cleaner to clean the powder metallurgy blank. The cleaning step is used to clean the surface dirt of the powder metallurgy blank after nitriding treatment.

[0063] In this embodiment, a cleaning step is further provided after the liquid nitriding step. The cleaning step uses a high-pressure spray machine and an ultrasonic cleaning machine to clean the powder metallurgy blank. The cleaning step is used to clean the dirt on the surface of the powder metallurgy blank after the nitriding treatment, thereby facilitating the removal of sand and dirt remaining on the surface of the powder metallurgy blank during the sandblasting process, thereby ensuring that the surface of the powder metallurgy blank is clean.

[0064] Inspection: The inspection steps include dimensional inspection and appearance inspection of powder metallurgy parts.

[0065] In this embodiment, an inspection step is provided after the cleaning step, and the inspection step performs dimensional inspection and appearance inspection on the powder metallurgy parts, thereby facilitating monitoring of the size and appearance of the powder metallurgy parts and preventing the outflow of defective products in size and appearance.

[0066] Oil immersion: The oil immersion step is to immerse the powder metallurgy parts in oil to prevent rust.

[0067] In this embodiment, an oil immersion step is further provided after the inspection step. In the oil immersion step, the powder metallurgy part is immersed in oil for rust prevention, thereby preventing the powder metallurgy part from rusting.

[0068] Packaging: The packaging step is to pack and box the powder metallurgy parts that have passed the inspection step.

[0069] In this embodiment, the powder metallurgy parts are subjected to salt bath nitriding treatment by adding a liquid nitriding step in the manufacturing process of the powder metallurgy parts, so that the final powder metallurgy parts can significantly improve the surface hardness of the powder metallurgy parts while ensuring the airtightness. The surface hardness of the powder metallurgy parts reaches above 500HV0.2, so that the surface of the small end face 120 of the upper floating plate of the powder metallurgy parts is also greater than the hardness of the sealing plate. Therefore, the wear of the small end face 120 of the upper floating plate can be reduced during the friction between the small end face 120 of the upper floating plate and the sealing plate, thereby ensuring the quality of the compressor.

[0070] The surface hardness of the conventional powder metallurgy parts without liquid nitriding treatment and the powder metallurgy parts after liquid nitriding treatment by the manufacturing method of this embodiment were tested, and the surface hardness comparison results shown in Table 1 were obtained.

[0071]

[0072] Table 1 According to the data comparison in Table 1, it can be known that the surface hardness of the powder metallurgy part manufactured by conventional process is much smaller than the surface hardness of the sealing plate 500HV0.2. When the small end face 120 of the powder metallurgy part manufactured by conventional process rubs against the sealing plate, the powder metallurgy part is easily worn by the sealing plate.

[0073] However, after randomly sampling 4 pieces of powder metallurgy parts manufactured by the manufacturing method of this embodiment and inspecting 3 positions of each product, the detected surface hardness was greater than the surface hardness of the sealing plate 500HV0.2. Therefore, the surface hardness of the powder metallurgy parts manufactured by the manufacturing method of this embodiment can be significantly improved, and the surface hardness is greater than the surface hardness of the sealing plate. When the small end face 120 of the powder metallurgy part manufactured by the manufacturing method of this embodiment rubs against the sealing plate, the powder metallurgy part is not easily worn by the sealing plate, thereby ensuring the quality of the compressor.

[0074] like Figure 4 The metallographic diagram of the powder metallurgy part manufactured by the manufacturing method of this embodiment is shown. Figure 4 It can be seen that the thickness of the nitriding layer of the powder metallurgy part is greater than 0.05 mm.

[0075] In the description of this specification, the description with reference to the terms "one embodiment, some embodiments, illustrative embodiments, examples, specific examples or some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0076] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for manufacturing a powder metallurgy part with high air tightness and high wear resistance, characterized in that: The following steps are involved: Pressing and molding: Use a mold to press the pre-mixed powder into a powder metallurgy blank; Sintering: The powder metallurgy blank obtained in the pressing step is sintered by heating and heat preservation in a protective gas; Steam treatment: The sintered powder metallurgy blank is placed in a heating furnace, and supersaturated steam is introduced into the heating furnace to allow the supersaturated steam to react chemically with the powder metallurgy blank and form a dense surface and pores of the powder metallurgy blank. ; Liquid nitriding: The powder metallurgy blank after water vapor treatment is immersed in a salt bath for salt bath nitriding. The nitriding time is 3.5h-4.5h and the nitriding temperature is 560℃-570℃.

2. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 1, characterized in that: The nitriding time is 4h.

3. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 1, characterized in that: The liquid nitriding step also includes a preheating step, which is arranged before the salt bath nitriding. In the preheating step, the powder metallurgy blank is placed on the tooling and preheated to 400°C.

4. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 1, characterized in that: The liquid nitriding step further includes a water cooling step, a cleaning step and a drying step which are performed in sequence, wherein the water cooling step, the cleaning step and the drying step are performed after the salt bath nitriding.

5. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 4, characterized in that: The drying step dries the powder metallurgy blank at 400° C. for 2 hours.

6. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 4, characterized in that: The liquid nitriding step further comprises a sandblasting step, which is arranged after the drying step, and the sandblasting step performs sandblasting on the surface of the powder metallurgy blank.

7. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 1, characterized in that: A cleaning step is also provided after the liquid nitriding step, and the cleaning step is used to clean the dirt on the surface of the powder metallurgy blank after the nitriding treatment.

8. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 7, characterized in that: An inspection step is also provided after the cleaning step, and the inspection step performs a dimensional inspection and an appearance inspection on the powder metallurgy part.

9. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 8, characterized in that: An oil immersion step is also provided after the inspection step, and the oil immersion step performs oil immersion on the powder metallurgy part to prevent rust.

10. The method for manufacturing a powder metallurgy part with high air tightness and high wear resistance according to claim 1, characterized in that: The sintering temperature of the sintering step is , the holding time is .

Images