CN112576507A - Manufacturing method of compressor piston and compressor piston - Google Patents

Manufacturing method of compressor piston and compressor piston Download PDF

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Publication number
CN112576507A
CN112576507A CN201910926181.3A CN201910926181A CN112576507A CN 112576507 A CN112576507 A CN 112576507A CN 201910926181 A CN201910926181 A CN 201910926181A CN 112576507 A CN112576507 A CN 112576507A
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piston
finished product
semi
treatment
iron
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CN201910926181.3A
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Chinese (zh)
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李海成
龙春仙
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Anhui Meizhi Precision Manufacturing Co Ltd
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Anhui Meizhi Precision Manufacturing Co Ltd
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Priority to CN201910926181.3A priority Critical patent/CN112576507A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/10—Cast-iron alloys containing aluminium or silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2230/00—Manufacture
    • F04C2230/40—Heat treatment
    • F04C2230/41—Hardening; Annealing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2230/00—Manufacture
    • F04C2230/90—Improving properties of machine parts
    • F04C2230/92—Surface treatment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00—Components
    • F04C2240/20—Rotors

Abstract

The application provides a manufacturing method of a compressor piston and the compressor piston, wherein the manufacturing method comprises the following steps: processing a base material to form a piston semi-finished product, wherein the base material is an iron-based powder metallurgy material or gray cast iron without nickel, chromium and molybdenum; carrying out heat treatment on the piston semi-finished product, wherein the heat treatment comprises carbonitriding treatment and low-temperature tempering treatment, or carburizing and quenching treatment and low-temperature tempering treatment; and processing the piston semi-finished product after the heat treatment to form a piston finished product. Through the mode, the piston which is low in cost and meets the requirement of wear resistance can be developed.

Description

Manufacturing method of compressor piston and compressor piston
Technical Field
The application relates to the technical field of compressors, in particular to a manufacturing method of a compressor piston and the compressor piston.
Background
The piston is one of the key parts of the rotary compressor, and the rotation of the piston can drive the volume change of the refrigerant in the two cavities in the cylinder. The piston is always balanced with the front end of the sliding sheet, so that the piston is required to have high wear resistance, air tightness and small thermal expansion coefficient. Conventional pistons use gray cast iron containing the elements nicr-mo, and the wear resistance of the piston surface is generally increased by reducing or removing the elements nicr-mo from the nicr-mo gray cast iron and by improving the heat treatment process.
The inventor of the present application found that the conventional gray cast iron containing elements of nickel, chromium and molybdenum has a high cost per se in the long-term research process, and the subsequent process for improving the wear resistance of the gray cast iron further increases the cost of the gray cast iron. Therefore, there is a need for a piston that is less expensive and meets wear resistance requirements.
Disclosure of Invention
The technical problem that this application mainly solved provides a compressor piston's manufacturing method, compressor piston, can develop a lower and satisfy the piston that the wearability required.
In order to solve the technical problem, the application adopts a technical scheme that: provided is a method for manufacturing a compressor piston, including: processing a base material to form a piston semi-finished product, wherein the base material is an iron-based powder metallurgy material or gray cast iron without nickel, chromium and molybdenum; carrying out heat treatment on the piston semi-finished product, wherein the heat treatment comprises carbonitriding treatment and low-temperature tempering treatment, or carburizing and quenching treatment and low-temperature tempering treatment; and processing the piston semi-finished product after the heat treatment to form a piston finished product.
When the base material is the gray cast iron material without nickel, chromium and molybdenum, the chemical components of the gray cast iron material without nickel, chromium and molybdenum comprise: c, carbon C: 3.0% -3.6%, Si: 1.4% -2.6%, Mn: 0.4-1.0%, phosphorus P: less than or equal to 0.20 percent, sulfur S: not more than 0.20 percent, and the balance of Fe, wherein the percentage is mass percent; or, when the base material is the iron-based powder metallurgy material, the chemical composition of the iron-based powder metallurgy material comprises iron Fe, carbon C, and alloying elements, wherein the alloying elements comprise at least one of copper Cu, nickel Ni, molybdenum Mo, and chromium Cr, wherein the ratio of carbon C: 0.6% -1.2%, copper Cu: less than or equal to 2.5 percent, nickel Ni: less than or equal to 2.1 percent, molybdenum Mo: less than or equal to 1.0 percent, Cr: less than or equal to 2.4 percent, and the balance of Fe, wherein the percentage is mass percent.
Wherein, when the base material is the gray cast iron material without nickel, chromium and molybdenum, the step of processing the base material to form a semi-finished piston product comprises the following steps: polishing the casting of the grey cast iron material without nickel, chromium and molybdenum to form the piston semi-product; alternatively, when the base material is the iron-based powder metallurgy material, the step of processing the base material to form a piston semi-finished product comprises: sintering and pressing the iron-based powder metallurgy material into the piston semi-finished product through a die, wherein the density of the sintered and pressed piston semi-finished product is 6.7cm2/g-7.5cm2/g。
Wherein the surface hardness of the piston semi-finished product and the piston finished product after the heat treatment is within the range of 50 +/-3 HRc.
Wherein, when the base material is the gray cast iron material without nickel, chromium and molybdenum, the metallographic structure of the semi-finished piston product after heat treatment comprises: tempered martensite, flake graphite, uniformly distributed carbide and residual austenite structures; or when the base material is the iron-based powder metallurgy material, the metallographic structure of the piston semi-finished product after heat treatment comprises: tempered martensite, carbides and retained austenite.
When the base material is the gray cast iron material without nickel, chromium and molybdenum, the metallographic structure of the piston semi-finished product which is not subjected to heat treatment is pearlite and ferrite, wherein flaky graphite is uniformly distributed in the pearlite; or when the base material is the iron-based powder metallurgy material, the metallographic structure of the piston semi-finished product which is not subjected to heat treatment comprises pearlite, ferrite and cementite.
Wherein, in the carbonitriding treatment or the carburizing and quenching treatment, the treatment temperature is 820-930 ℃, and/or the carbon potential is 0.8-1.2%, and/or the treatment time is 3-5 hours.
Wherein in the low-temperature tempering treatment, the treatment temperature is 180-220 ℃, and/or the treatment time is 2.5-3.5 hours.
In order to solve the above technical problem, another technical solution adopted by the present application is: there is provided a compressor piston manufactured by the manufacturing method of any one of the above.
Wherein the compressor piston is applied in a rotary compressor.
The beneficial effect of this application is: the forming material of the compressor piston is gray cast iron or iron-based powder metallurgy material without nickel-chromium-molybdenum, and the surface hardness is improved after carbonitriding treatment and low-temperature tempering treatment or carburizing quenching treatment and low-temperature tempering treatment, so that the wear resistance equivalent to that of the original nickel-chromium-molybdenum cast iron piston can be achieved; when the compressor piston is made of gray cast iron without nickel, chromium and molybdenum, the wear resistance of the surface of the piston is improved directly through the heat treatment process, and the step of removing nickel, chromium and molybdenum elements in the gray cast iron is omitted, so that the cost for preparing the compressor piston can be reduced; when the forming material of the compressor piston is an iron-based powder metallurgy material, the process of processing the powder metallurgy material to form a piston semi-finished product is simple, the process can be simplified, and therefore the cost for preparing the compressor piston can be reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:
FIG. 1 is a schematic flow chart illustrating one embodiment of a method for manufacturing a piston for a compressor according to the present application;
FIG. 2 is a schematic structural view of an embodiment of a piston of the compressor of the present application;
fig. 3 is a schematic structural diagram of an embodiment of a compression mechanism of a rotary compressor.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 is a schematic flow chart illustrating an embodiment of a method for manufacturing a piston of a compressor according to the present application, the method comprising:
s101: and processing the base material to form a semi-finished piston product, wherein the base material is an iron-based powder metallurgy material or gray cast iron without nickel, chromium and molybdenum.
Specifically, the gray cast iron refers to cast iron with flake graphite, the main components comprise iron, carbon, silicon, manganese, sulfur, phosphorus and the like, and the base material provided by the application is gray cast iron without nickel, chromium and molybdenum, such as gray cast iron with the brands of HT250, HT200, HT150 and the like; wherein the lowest tensile strength of a phi 30mm sample with the mark of HT250 is 250MPa, the lowest tensile strength of a phi 30mm sample with the mark of HT200 is 200MPa, and the lowest tensile strength of a phi 30mm sample with the mark of HT150 is 150 MPa. In this example, the chemical composition of the gray cast iron material without nickel, chromium and molybdenum includes: c, carbon C: 3.0% to 3.6% (e.g., 3.2%, 3.4%, etc.), silicon Si: 1.4% to 2.6% (e.g., 1.8%, 2.0%, 2.2%, etc.), manganese Mn: 0.4% to 1.0% (e.g., 0.6%, 0.8%, etc.), phosphorus P: less than or equal to 0.20 percent, sulfur S: less than or equal to 0.20 percent, and the balance of Fe, wherein the percentage is mass percent. The carbon element in the composition can promote graphitization, and can exist in two forms of free carbon (graphite) and cementite in the casting, so that the mechanical property of the gray cast iron can be improved. The silicon element can promote graphitization and has a solid solution strengthening effect on the gray cast iron. The manganese element may be combined with the sulfur element in the gray cast iron to reduce the effect of the sulfur element. Phosphorus and sulfur are inevitable impurity elements in gray cast iron, and the content of the phosphorus and the sulfur needs to be controlled. The compressor piston formed by the gray cast iron without nickel, chromium and molybdenum containing the chemical components has higher hardness and better wear resistance.
In this embodiment, when the base material is a gray cast iron material without nickel, chromium and molybdenum, the step S101 of processing the base material to form a semi-finished piston product includes: the casting of the grey cast iron material without nickel, chromium and molybdenum is polished to form a piston semi-product, and the polishing can be performed by automatic mechanical polishing equipment in the prior art. The processing mode and the process are simple.
The raw materials of the iron-based powder metallurgy material are powdered iron powder and alloy steel powder, the iron-based powder metallurgy material has unique chemical composition, physical and mechanical properties which cannot be obtained by the traditional casting process, and has the advantages of controllable porosity, uniform material structure, no macrosegregation, one-step forming and the like. In this example, the chemical composition of the iron-based powder metallurgy material includes: fe, carbon C and alloy elements, wherein the alloy elements comprise at least one of Cu, Ni, Mo and Cr, and the ratio of carbon C: 0.6% -1.2% (e.g., 0.8%, 1.0%, etc.), copper Cu: 2.5% (e.g., 1.2%, 1.8%, 2.0%, etc.), nickel Ni: 2.1% (e.g., 0%, 1.0%, 2.0%, etc.), molybdenum Mo: 1.0% (e.g., 0, 0.5%, etc.), chromium Cr: 2.4 percent or less (for example, 0, 1.0 percent, 2.0 percent and the like), and the balance of Fe, wherein the percentage is the mass percentage.
Part of carbon elements in the composition can be dissolved in iron to form interstitial solid solution to play a role in solid solution strengthening, the number of metal oxides can be reduced, the mechanical property is improved, and part of carbon elements form free graphite to play a role in lubrication. The alloy elements can play a role in solid solution strengthening, have low melting points, can be melted firstly in the iron-based powder metallurgy sintering process to generate an instantaneous liquid phase, and play roles in lubricating and promoting sintering. The compressor piston formed by the iron-based powder metallurgy material with the chemical components has higher hardness and better wear resistance.
In this embodiment, when the base material is an iron-based powder metallurgy material, the step S101 of processing the base material to form a piston semi-finished product includes: sintering and pressing the iron-based powder metallurgy material into a piston semi-finished product through a die, wherein the density of the sintered and pressed piston semi-finished product is 6.7cm2/g-7.5cm2G (e.g., 6.9 cm)2/g、7.1cm2/g、7.3cm2In terms of/g, etc.). Specifically, the alloying element powder, the carbon powder and the iron powder can be uniformly mixed according to a preset weight percentage; then putting the uniformly mixed raw materials into a steel mould, and pressing the raw materials into a piston semi-finished product in a mould pressing forming mode; and then, putting the piston semi-finished product into a sintering furnace for sintering, wherein nitrogen can be introduced for protection in the sintering process. The mode of forming the semi-finished product through pressing and sintering does not need the process of rough machining (namely grinding) of the traditional casting and forging piece, so that the method has the advantages of saving materials, simplifying the process and reducing the cost.
S102: and carrying out heat treatment on the piston semi-finished product, wherein the heat treatment comprises carbonitriding treatment and low-temperature tempering treatment, or carburizing and quenching treatment and low-temperature tempering treatment.
Specifically, the carbonitriding treatment is a chemical surface heat treatment process for simultaneously infiltrating carbon and nitrogen into the surface of the piston semi-finished product, and the nitrogen and the carbon are simultaneously diffused into the piston semi-finished product to form a nitrogen-containing carburized layer so as to improve the hardness of the surface of the piston semi-finished product and further improve the wear resistance of the piston semi-finished product. The specific carbonitriding treatment process can be as follows: the semi-finished piston to be treated is put into a carburizing furnace, carbonitriding treatment is carried out, and treatment is carried out for 3 to 5 hours (for example, 4 hours) under the conditions that the treatment temperature is 820 to 930 ℃ (for example, 840 ℃, 860 ℃, 900 ℃ and the like) and the carbon potential is 0.8 to 1.2% (for example, 0.9, 1.0% and the like).
The carburizing and quenching treatment is a chemical surface heat treatment process for infiltrating carbon into the surface of the piston semi-finished product so as to improve the hardness of the surface of the piston semi-finished product and further improve the wear resistance of the piston semi-finished product. The specific carburizing and quenching treatment process can be as follows: the piston semi-finished product is put into a medium with active carburization and treated for 3 to 5 hours (for example, 4 hours and the like) under the conditions that the treatment temperature is 820 to 930 ℃ (for example, 840 ℃, 860 ℃, 900 ℃ and the like) and the carbon potential is 0.8 to 1.2 percent (for example, 0.9, 1.0 and the like).
Because the piston semi-finished product can generate internal stress inside through the carbonitriding or carburizing and quenching high-temperature treatment process, the plasticity and the toughness are reduced, in order to further improve the comprehensive performance of the piston semi-finished product, the piston semi-finished product is subjected to low-temperature tempering treatment after the carbonitriding or carburizing and quenching treatment, and the low-temperature tempering process comprises the following steps: and (3) heating the piston semi-finished product subjected to carbonitriding treatment or carburizing and quenching treatment to a proper treatment temperature, preserving heat for a plurality of times, and then slowly or quickly cooling. In this embodiment, the treatment temperature of the low temperature tempering treatment is 180 to 220 ℃, for example, 190 ℃, 200 ℃, 210 ℃ or the like; and/or the treatment time is 2.5 hours to 3.5 hours, e.g., 3 hours, etc. The number of times of the low-temperature tempering treatment may be one or more.
In addition, in the present embodiment, when the base material is a gray cast iron material containing no nickel, chromium and molybdenum, the metallographic structure of the piston semi-finished product after heat treatment includes: tempered martensite, flake graphite, uniformly distributed carbide and residual austenite structures; when the base material is an iron-based powder metallurgy material, the metallographic structure of the piston semi-finished product after heat treatment comprises: tempered martensite, carbides and retained austenite.
The tempered martensite is a sheet martensite (the crystal structure is face-centered cubic) formed in carbonitriding or carburizing and quenching treatment and is decomposed in a first tempering stage, wherein carbon is formed in a form of transition carbide by desolventizing, and a complex phase structure of extremely fine transition carbide sheets (the interface with a matrix is a coherent interface) is dispersed and distributed in a solid solution matrix (the crystal structure is changed into the body-centered cubic), so that the tempered martensite has high hardness and high wear resistance, and the toughness is improved due to the reduction of internal stress. The carbide is a binary compound consisting of metal or nonmetal and carbon, can be granular and is uniformly distributed in a metallographic structure, and the granular carbide can improve the comprehensive mechanical property of a piston semi-finished product. The residual austenite structure is a part which is not transformed in the carbonitriding or carburizing and quenching process, the residual austenite structure with a small amount has certain toughness, exists between tempered martensite with high strength in a film shape or a block shape, can release stress at the tip of a crack, increases energy required by crack propagation, can effectively prevent crack propagation, and improves the overall strength and the toughness to a certain extent. When the heat treatment process includes carbonitriding, the formed tempered martensite is a tempered martensite containing nitrogen.
Further, in the present embodiment, when the base material is a gray cast iron material containing no nickel, chromium and molybdenum, the metallographic structure of the piston semi-finished product that has not been heat-treated (i.e., the piston semi-finished product provided in step S101) is pearlite and ferrite, in which lamellar graphite is uniformly distributed in the pearlite. In a specific application scenario, the ferrite content in the metallographic structure of the non-heat-treated piston semi-finished product is less than 5% (e.g., 4%, 3%, etc.), the majority of graphite is type a graphite, and the total amount of type B, type C, type D, and type E graphite is less than 30% (e.g., 25%, 20%, etc.); the contents are all mass percent. The control of the ferrite content and the graphite type can make the gray cast iron have relatively high strength and hardness and good wear resistance.
When the base material is an iron-based powder metallurgy material, the metallographic structure of the piston semi-product that has not been heat-treated (i.e., the piston semi-product provided in step S101) includes pearlite, ferrite, and cementite; wherein ferrite is a solid solution of carbon C in alpha-Fe, and cementite is a compound formed by combining carbon C with FeThe chemical formula is Fe3And C, pearlite is a mixture formed by ferrite and a cementite, and the powder metallurgy material with the metallographic structure has relatively high strength and hardness and good wear resistance.
In addition, the surface hardness of the piston semi-finished product after the heat treatment can reach 50 +/-3 HRc (namely 47 to 53HRc), such as 48HRc, 50HRc and the like. The surface hardness is equivalent to that of the traditional gray cast iron containing nickel, chromium and molybdenum elements.
S103: and processing the piston semi-finished product after heat treatment to form a piston finished product.
Specifically, the heat-treated piston semi-finished product may be subjected to a finishing process to form a piston finished product. In this embodiment, the surface hardness of the piston product formed by the above-mentioned grinding and finishing process can reach 50 ± 3HRc (i.e. 47HRc to 53HRc), for example, 48HRc, 50HRc, etc. The surface hardness is equivalent to that of the traditional gray cast iron containing nickel, chromium and molybdenum elements.
The method for manufacturing a piston for a compressor provided by the present application is further described below with several embodiments.
The first embodiment is as follows:
firstly, carrying out rough machining on a gray cast iron casting with the mark of HT250 to form a piston semi-finished product; then carrying out carbonitriding treatment/carburizing and quenching treatment on the piston semi-finished product, wherein the treatment temperature of the carbonitriding treatment/carburizing and quenching treatment is 900 ℃, the carbon potential is 1.1%, and the carburizing time is 4 hours; then, carrying out low-temperature tempering treatment on the piston semi-finished product, wherein the heat preservation temperature is 200 ℃, and the heat preservation time is 3 hours; and finally, performing finish machining on the heat-treated piston semi-finished product to form a piston finished product, wherein the surface hardness of the piston finished product is 50 +/-3 HRc.
Example two:
firstly, directly sintering an iron-based powder metallurgy material into a piston semi-finished product through a grinding tool, wherein the iron-based powder metallurgy material comprises the following chemical components in percentage by weight: 0.8 percent of C, 1.6 percent of Cu1.6 percent of Fe and the balance of Fe, and the density of the pressed piston semi-finished product is 7.1cm2(ii)/g; then the semi-finished product of the piston is subjected to carbonitriding treatment/carburizing and quenching treatment, carbonitriding treatment/carburizingThe processing temperature of carbon quenching treatment is 880 ℃, the carbon potential is 1.1 percent, and the carburizing time is 4 hours; then, carrying out low-temperature tempering treatment on the piston semi-finished product, wherein the heat preservation temperature is 200 ℃, and the heat preservation time is 3 hours; and finally, performing finish machining on the heat-treated piston semi-finished product to form a piston finished product, wherein the surface hardness of the piston finished product is 50 +/-3 HRc.
Referring to fig. 2-3, fig. 2 is a schematic structural view of an embodiment of a piston of a compressor according to the present application, and fig. 3 is a schematic structural view of an embodiment of a compression mechanism of a rotary compressor. The compressor piston is manufactured by the manufacturing method in any one of the above embodiments, the specific shape of the compressor piston 100 is not limited in the present application, and the compressor piston 100 provided in the present application may be applied to a rotary compressor, a reciprocating compressor, and the like.
The following description will be made by taking a rotary compressor as an example. The rotary compressor, which may be generally used in an air conditioner, a refrigerator, or the like, includes a housing, and a motor part and a compression mechanism 10 disposed in the housing, wherein the motor part is used to output a rotational power, and the compression mechanism 10 and the motor part perform a motion transmission via a crankshaft. The compression mechanism 10 includes a piston 100 that eccentrically rotates by being driven by a crankshaft, and a cylinder 102 that engages with the piston 100, and a compression chamber 104 is formed between an inner peripheral surface of the cylinder 102 and an outer peripheral surface of the piston 100. A sliding piece mounting groove (not marked) is formed in the cylinder 102, a sliding piece 106 is movably arranged in the sliding piece mounting groove, and a front end a of the sliding piece 106 extends out of the sliding piece mounting groove and abuts against the outer peripheral surface of the piston 100 so as to divide the compression cavity 104 into an air suction cavity and an air exhaust cavity. Since the piston 100 and the front end a of the sliding vane 106 always abut against each other, the piston 100 provided by the present application is required to have high wear resistance.
In one embodiment, the compressor piston 100 is formed from a gray cast iron material without nickel, chromium, and molybdenum, and includes the following chemical components: c, carbon C: 3.0% to 3.6% (e.g., 3.2%, 3.4%, etc.), silicon Si: 1.4% to 2.6% (e.g., 1.8%, 2.0%, 2.2%, etc.), manganese Mn: 0.4% to 1.0% (e.g., 0.6%, 0.8%, etc.), phosphorus P: less than or equal to 0.20 percent, S: less than or equal to 0.20 percent, and the balance of Fe, wherein the percentage is mass percent. Alternatively, the compressor piston is formed from an iron-based powder metallurgy material having a chemical composition comprising: fe, carbon C and alloy elements, wherein the alloy elements comprise at least one of Cu, Ni, Mo and Cr, and the ratio of carbon C: 0.6% -1.2% (e.g., 0.8%, 1.0%, etc.), copper Cu: 2.5% (e.g., 1.2%, 1.8%, 2.0%, etc.), nickel Ni: 2.1% (e.g., 0%, 1.0%, 2.0%, etc.), molybdenum Mo: 1.0% (e.g., 0, 0.5%, etc.), chromium Cr: 2.4 percent or less (for example, 0, 1.0 percent, 2.0 percent and the like), and the balance of Fe, wherein the percentage is the mass percentage.
In another embodiment, the surface hardness of the compressor piston can be up to 50 ± 3HRc (i.e., 47HRc to 53HRc), e.g., 48HRc, 50HRc, etc.
In yet another embodiment, when the compressor piston is made of a gray cast iron material that does not include nickel, chromium, molybdenum, the metallographic structure of the compressor piston includes: tempered martensite, flake graphite, uniformly distributed carbide and residual austenite structures; when the compressor piston is made of an iron-based powder metallurgy material, the metallographic structure of the compressor piston comprises: tempered martensite, carbides and retained austenite.
In summary, the forming material of the compressor piston is gray cast iron or iron-based powder metallurgy material without nickel, chromium and molybdenum, and the surface hardness of the material is improved after carbonitriding treatment and low-temperature tempering treatment or carburizing quenching treatment and low-temperature tempering treatment, so that the wear resistance equivalent to that of the original nickel, chromium and molybdenum cast iron piston can be achieved; when the compressor piston is made of gray cast iron without nickel, chromium and molybdenum, the wear resistance of the surface of the piston is improved directly through the heat treatment process, and the step of removing nickel, chromium and molybdenum elements in the gray cast iron is omitted, so that the cost for preparing the compressor piston can be reduced; when the forming material of the compressor piston is an iron-based powder metallurgy material, the process of processing the powder metallurgy material to form a piston semi-finished product is simple, the process can be simplified, and therefore the cost for preparing the compressor piston can be reduced.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims (10)

1. A method of manufacturing a compressor piston, comprising:
processing a base material to form a piston semi-finished product, wherein the base material is an iron-based powder metallurgy material or gray cast iron without nickel, chromium and molybdenum;
carrying out heat treatment on the piston semi-finished product, wherein the heat treatment comprises carbonitriding treatment and low-temperature tempering treatment, or carburizing and quenching treatment and low-temperature tempering treatment;
and processing the piston semi-finished product after the heat treatment to form a piston finished product.
2. The method of manufacturing according to claim 1, wherein when the substrate is the gray cast iron material free of nickel-chromium-molybdenum, the chemical composition of the gray cast iron material free of nickel-chromium-molybdenum comprises: c, carbon C: 3.0% -3.6%, Si: 1.4% -2.6%, Mn: 0.4-1.0%, phosphorus P: less than or equal to 0.20 percent, sulfur S: not more than 0.20 percent, and the balance of Fe, wherein the percentage is mass percent; alternatively, the first and second electrodes may be,
when the base material is the iron-based powder metallurgy material, the chemical composition of the iron-based powder metallurgy material comprises iron Fe, carbon C and alloy elements, wherein the alloy elements comprise at least one of copper Cu, nickel Ni, molybdenum Mo and chromium Cr, wherein the ratio of carbon C: 0.6% -1.2%, copper Cu: less than or equal to 2.5 percent, nickel Ni: less than or equal to 2.1 percent, molybdenum Mo: less than or equal to 1.0 percent, Cr: less than or equal to 2.4 percent, and the balance of Fe, wherein the percentage is mass percent.
3. The method of manufacturing according to claim 2, wherein when the base material is the gray cast iron material free of nickel-chromium-molybdenum, the step of processing the base material to form a piston semi-finished product includes: polishing the casting of the grey cast iron material without nickel, chromium and molybdenum to form the piston semi-product; alternatively, the first and second electrodes may be,
when the substrate is the iron-based powder metallurgy material, the step of processing the substrate to form a semi-finished piston product comprises the following steps: sintering and pressing the iron-based powder metallurgy material into the piston semi-finished product through a die, wherein the density of the sintered and pressed piston semi-finished product is 6.7cm2/g-7.5cm2/g。
4. The manufacturing method according to claim 1,
and the surface hardness of the piston semi-finished product and the piston finished product after the heat treatment is within the range of 50 +/-3 HRc.
5. The manufacturing method according to claim 1,
when the base material is the gray cast iron material without nickel, chromium and molybdenum, the metallographic structure of the semi-finished piston product after heat treatment comprises: tempered martensite, flake graphite, uniformly distributed carbide and residual austenite structures; alternatively, the first and second electrodes may be,
when the base material is the iron-based powder metallurgy material, the metallographic structure of the piston semi-finished product after heat treatment comprises: tempered martensite, carbides and retained austenite.
6. The manufacturing method according to claim 5,
when the base material is the gray cast iron material without nickel, chromium and molybdenum, the metallographic structure of the piston semi-finished product which is not subjected to heat treatment is pearlite and ferrite, wherein flaky graphite is uniformly distributed in the pearlite; alternatively, the first and second electrodes may be,
when the base material is the iron-based powder metallurgy material, the metallographic structure of the piston semi-finished product which is not subjected to heat treatment comprises pearlite, ferrite and cementite.
7. The manufacturing method according to claim 1,
in the carbonitriding treatment or the carburizing and quenching treatment, the treatment temperature is 820-930 ℃, and/or the carbon potential is 0.8-1.2%, and/or the treatment time is 3-5 hours.
8. The manufacturing method according to claim 1,
in the low-temperature tempering treatment, the treatment temperature is 180-220 ℃, and/or the treatment time is 2.5-3.5 hours.
9. Compressor piston, characterized in that it is manufactured with the manufacturing method according to any one of claims 1 to 8.
10. The compressor piston as set forth in claim 9, wherein said compressor piston is employed in a rotary compressor.
CN201910926181.3A 2019-09-27 2019-09-27 Manufacturing method of compressor piston and compressor piston Pending CN112576507A (en)

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Application publication date: 20210330