CN114921743A - Method for prolonging service life of pressure chamber and injection head of die-casting machine by using composite coating - Google Patents
Method for prolonging service life of pressure chamber and injection head of die-casting machine by using composite coating Download PDFInfo
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- CN114921743A CN114921743A CN202210563585.2A CN202210563585A CN114921743A CN 114921743 A CN114921743 A CN 114921743A CN 202210563585 A CN202210563585 A CN 202210563585A CN 114921743 A CN114921743 A CN 114921743A
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
- C23C4/06—Metallic material
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
- C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
- C23C4/129—Flame spraying
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- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/18—After-treatment
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention relates to the technical field of surface engineering, and discloses a method for prolonging the service life of a pressure chamber and an injection head of a die casting machine by using a composite coating, which comprises the following steps: s1) boring and grinding to remove the surface layer of the surface to be processed to form a processed surface; s2) carrying out sand blasting by adopting a supersonic flame spraying process to form a roughened surface; s3) spraying a spray gun above the roughened surface to form a self-fluxing alloy bottom layer; s4) continuously preparing a tungsten carbide surface layer on the surface of the self-fluxing alloy bottom layer; s5) heating and remelting by using a high-frequency induction heating system to form a metallurgical bonding transition layer; s6) adopting a honing machine to bore and grind into matched sizes, namely manufacturing a pressure chamber and an injection plunger covered with the composite coating; the nickel-based self-melting alloy layer is heated and remelted from the interior of the workpiece by utilizing an induction heating remelting technology, so that the tungsten carbide coating is prevented from being subjected to high-temperature oxidation decarburization, and the service lives of a pressure chamber and an injection head of a die casting machine are obviously prolonged.
Description
Technical Field
The invention relates to the technical field of surface engineering, in particular to a method for prolonging the service life of a pressure chamber and an injection head of a die-casting machine by using a composite coating.
Background
The base materials of a pressure chamber and an injection head of the aluminum die-casting machine are H13 die steel, the pressure chamber and the injection head need to bear high temperature and high pressure during working, severe friction force is generated between the pressure chamber and the injection head, and the pressure chamber and the injection head are easy to lose efficacy due to abrasion and thermal fatigue, so that the service life is obviously reduced.
The surface nitriding process in the prior art has the characteristics of low cost, convenience and practicability, and is used for improving the surface hardness of an H13 steel die, a nitriding layer is formed on the surface of the die steel H13 after nitriding treatment, but the thickness of the nitriding layer is only 2-3 mu m, the service life of a pressure chamber is about 1-1.2 ten thousand times, the service life of an injection plunger is about 3000-4000 times, the improvement of the service life is limited, the requirements of the existing large-scale production cannot be met, the frequency of shutdown maintenance is high, and the production efficiency is influenced.
Disclosure of Invention
Based on the above technical defects, the invention provides a method for prolonging the service life of a pressure chamber and an injection head of a die-casting machine by using a composite coating, which not only has higher hardness, but also has large thickness of a metallurgical bonding transition layer on the surface, and can further prolong the service life of the pressure chamber and the injection head.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for prolonging the service life of a pressure chamber and an injection head of a die casting machine by using a composite coating comprises the following steps:
s1) plugging a feed inlet of a pressure chamber to be processed, defining two contact surfaces of the pressure chamber and an injection plunger as surfaces to be processed during operation, carrying out boring and grinding processing on the two surfaces to be processed by adopting a honing machine, and removing the surface layer of the surface to be processed by boring and grinding to form a processing surface;
s2) carrying out sand blasting on the machined surface by adopting a supersonic flame spraying process to form a sand blasting surface, baking the sand blasting surface by using supersonic flame, and then cleaning the sand blasting surface by using compressed air to form a roughened surface;
s3) spraying nickel-based self-fluxing alloy powder on the two coarsening surfaces of the pressure chamber and the injection plunger respectively by using an excircle spray gun and an inner hole spray gun of the supersonic flame spraying system to form a self-fluxing alloy bottom layer above the coarsening surfaces;
s4) continuously spraying tungsten carbide powder on the surface of the self-fluxing alloy bottom layer by using an excircle spray gun and an inner hole spray gun to prepare a tungsten carbide surface layer;
s5) heating and remelting the self-fluxing alloy bottom layer by using a high-frequency induction heating system, so that the self-fluxing alloy bottom layer, the substrate and the tungsten carbide surface layer are metallurgically bonded to form a metallurgical bonding transition layer, and naturally cooling to obtain a standby workpiece with a composite coating covered on the surface;
s6) adopting a honing machine to bore and mill the metallurgical bonding transition layers of the two standby workpieces into matched sizes, namely manufacturing a pressure chamber and an injection plunger which are covered with the composite coating.
Preferably, in step S1), before the boring and milling process, the region outside the surface to be processed is protected by tool wrapping, the feed port of the pressure chamber is blocked by spot welding, and the pressure chamber and the injection head are cleaned by ultrasonic for 10min by using a deconextht 170 cleaning agent.
Preferably, in step S2), the sand powder for sand blasting is alumina powder with the fineness of 150-220 meshes, the air pressure of compressed air is 0.6MPa, and the powder feeding amount of sand blasting is 95-105 g/min.
Preferably, in the step S3), the thickness of the self-fluxing alloy bottom layer is not more than 50% of the thickness of the composite coating, the nickel-based self-fluxing alloy powder is 300-400 mesh Ni60CuMo powder, and the powder feeding amount of spraying is 48-50 g/min.
Preferably, in the step S4), the thickness of the tungsten carbide surface layer is not less than 70% of the thickness of the composite coating, and the powder feeding amount of spraying is 75-85 g/min; the tungsten carbide powder is 5-38 μm WC-12 Ni.
Preferably, in step S5), a lihua LHA-70kw high-frequency induction heating system is adopted, argon is used as a protective atmosphere, the flow rate of argon is 40l/min, the oscillation frequency is 48kHz, the oscillation current is 950A, the moving speed is 200mm/min, and the surface roughness of the standby workpiece is ra 2.5-3.0.
Preferably, in step S5), the thickness of the composite coating is 0.2-0.25 mm.
Preferably, in step S6), the boring and milling process is performed at a milling linear speed of 150 m/min, a feeding speed of 120mm/min, and a milling amount per time of not more than 0.03mm, and at least three times of milling are performed to meet the process requirements.
Preferably, in step S6), in step S6), the microhardness HV0.3 of the composite coating is greater than 900, the porosity of the composite coating is less than 1%, and the thickness of the composite coating remaining after processing is not less than 0.2 mm.
The technical scheme of the invention has the beneficial effects that: the method for prolonging the service life of the pressure chamber and the injection head of the die-casting machine by using the composite coating comprises the steps of preparing the composite coating with metallurgical bonding characteristics on the surfaces of the pressure chamber and the workpiece of the injection head by using thermal spraying and induction heating technologies, spraying nickel-based self-melting alloy by using a supersonic spraying technology, preparing a self-melting alloy bottom layer with uniform distribution and controllable thickness on the surface of the workpiece, spraying tungsten carbide powder by using a high-energy supersonic spraying technology, forming a high-density tungsten carbide surface layer on the surface of the self-melting alloy bottom layer, heating and remelting the nickel-based self-melting alloy layer from the inside of the workpiece by using an induction heating and remelting technology, so that the tungsten carbide is prevented from being decarburized due to high-temperature oxidation, a metallurgical bonding transition layer with high bonding force and high wear resistance is formed by using the nickel-based self-melting alloy layer, and the prepared composite coating covered by the pressure chamber and the injection head has good thermal fatigue resistance performance, The hardness is high, the thickness can be processed according to the requirement, and the service life of a pressure chamber and an injection head of the die-casting machine can be obviously prolonged.
Drawings
FIG. 1 is a metallographic representation of the metallographic structure of a composite coating according to an embodiment of the invention;
FIG. 2 is a metallographic structure at 100 times magnification of a composite coating according to an embodiment of the invention.
Detailed Description
In the description herein, references to the description of the terms "embodiment," "example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
The technical solution of the present invention will be further described with reference to the following embodiments.
A method for improving the service life of a pressure chamber and an injection head of a die-casting machine by using a composite coating comprises the following steps:
s1) plugging a feed inlet of a pressure chamber to be processed, defining two contact surfaces of the pressure chamber and an injection plunger as surfaces to be processed during operation, and carrying out boring and grinding processing on the two surfaces to be processed by adopting a honing machine, wherein the surface layer of the surface to be processed is removed by the boring and grinding machine to form a processing surface;
s2) carrying out sand blasting on the processing surface by adopting a supersonic flame spraying process to form a sand blasting surface, baking the sand blasting surface by using supersonic flame, and then cleaning the sand blasting surface by using compressed air to form a roughened surface;
s3) spraying nickel-based self-fluxing alloy powder on the two coarsening surfaces of the pressure chamber and the injection plunger respectively by using an excircle spray gun and an inner hole spray gun of the supersonic flame spraying system, and forming a self-fluxing alloy bottom layer above the coarsening surfaces;
s4) continuously spraying tungsten carbide powder on the surface of the self-fluxing alloy bottom layer by using an excircle spray gun and an inner hole spray gun to prepare a tungsten carbide surface layer;
s5) heating and remelting the self-fluxing alloy bottom layer by using a high-frequency induction heating system, enabling the self-fluxing alloy bottom layer, the substrate and the tungsten carbide surface layer to generate metallurgical bonding to form a metallurgical bonding transition layer, and naturally cooling to obtain a standby workpiece with the surface covered with a composite coating;
s6) adopting a honing machine to bore and mill the metallurgical bonding transition layers of the two standby workpieces into matched sizes, namely manufacturing a pressure chamber and an injection plunger which are covered with the composite coating.
The invention relates to a method for prolonging the service life of a pressure chamber and an injection head of a die-casting machine by using a composite coating, which is characterized in that the composite coating with metallurgical bonding characteristics is prepared on the surfaces of a pressure chamber and the workpiece of the injection head by using thermal spraying and induction heating technologies, a nickel-based self-fluxing alloy is sprayed by using a supersonic spraying technology, a self-fluxing alloy bottom layer with uniform distribution and controllable thickness is prepared on the surface of the workpiece, tungsten carbide powder is sprayed by using a high-energy supersonic spraying technology, a high-density tungsten carbide surface layer is formed on the surface of the self-fluxing alloy bottom layer, and finally the nickel-based self-fluxing alloy layer is heated and remelted from the inside of the workpiece by using an induction heating remelting technology, so that the tungsten carbide is prevented from being decarburized by high-temperature oxidation, the nickel-based self-fluxing alloy layer forms a metallurgical bonding transition layer with high bonding force and high wear resistance with the matrix of the workpiece and the tungsten carbide coating on the surface, and the prepared pressure chamber and injection head have good fatigue resistance, The hardness is high, and the thickness can be processed as required, and then can show the life who improves the pressure chamber of die casting machine and injection plunger.
When an induction heating process is adopted for heating, only the metal part of the matrix with increased resistance can absorb electromagnetic waves to be heated, the surface coatings comprising the nickel-based self-fluxing alloy bottom layer and the tungsten carbide surface layer cannot be directly heated by the electromagnetic waves, the power of induction heating and the moving speed of the induction coil are controlled, heat can be conducted from the surface of the matrix to the nickel-based self-fluxing alloy bottom layer, the nickel-based self-fluxing alloy bottom layer is heated and remelted, the tungsten carbide coating surface layer is kept at a lower temperature, the temperature of the tungsten carbide surface layer is prevented from exceeding 500 ℃, the phenomenon of decarburization and delamination of the tungsten carbide surface layer caused by high-temperature oxidation of tungsten carbide in the tungsten carbide surface layer is avoided, and further, the mechanical performance of the composite coating is prevented from being damaged in the heating and remelting process.
Preferably, in step S1), before the boring and milling process, the region outside the surface to be processed is protected by tool wrapping, the feed port of the pressure chamber is blocked by spot welding, and the pressure chamber and the injection head are cleaned by ultrasonic for 10min by using a deconextht 170 cleaning agent.
The region outside the surface to be treated is protected by using the tool for wrapping, the feed inlet of the pressure chamber is blocked by adopting spot welding, the performance of the region outside the surface to be treated and the performance of the feed inlet can be prevented from being influenced by subsequent processing, the pressure chamber and the injection head are cleaned by using a cleaning agent and ultrasonic waves, surface oil stains of the pressure chamber and the injection head can be effectively removed, and the adhesive force of the composite coating is improved.
The thickness of the surface layer removed by the boring and milling can be selected or adjusted according to requirements and the surface states of the pressure chamber and the injection plunger.
Preferably, in the step S2), the sand powder for sand blasting is alumina powder with the fineness of 150-220 meshes, the air pressure of compressed air is 0.6MPa, and the powder feeding amount of sand blasting is 95-105 g/min.
150-220-mesh aluminum oxide powder is adopted, the machined surface is roughened by sand blasting, flame cleaning and roughening before spraying of the injection head and the pressure chamber can be realized simultaneously, the adhesive force of the composite coating on the surface of the matrix can be further improved, and the hardness of the base material of the injection head and the pressure chamber after heat treatment is higher and is greater than HRC 50.
The alumina powder has higher hardness and better self-sharpening property than other powders, and does not change physical state and physical properties in supersonic flame.
Preferably, in the step S3), the thickness of the self-fluxing alloy bottom layer is not more than 50% of the thickness of the composite coating, the nickel-based self-fluxing alloy powder is 300-400-mesh Ni60CuMo powder, and the powder feeding amount of the spraying is 48-50 g/min.
The thickness of the sprayed self-melting alloy bottom layer can be adjusted according to the thickness of the composite coating to be processed, the thickness of the self-melting alloy bottom layer is set to be about 50% of the thickness of the composite coating, the thickness of the self-melting alloy bottom layer is close to that of the sprayed tungsten carbide surface layer, mutual permeation of the nickel-based self-melting alloy and tungsten carbide between the tungsten carbide surface layer and the self-melting alloy bottom layer during heating remelting is facilitated, and then the uniform distribution state is achieved.
The Ni60CuMo powder is used as nickel-based self-fluxing alloy powder, does not contain iron-based materials, has extremely low magnetic conductivity, and cannot be acted by an electromagnetic coil in the induction heating process, and the addition of Cu in the powder improves the heat-conducting property of a formed coating and has an optimization effect on the uniformity of heat conduction of a matrix after induction heating.
The particle size range of 300-400 mesh is a powder particle size range suitable for the HVAF supersonic flame spray gun, and the powder in the particle size range can be just formed into particles in a molten state, so that the coating inclusion cannot be formed because the powder particles are too large and are not completely melted, and the coating composition cannot be changed because the powder particles are smaller and are excessively melted or even evaporated.
Preferably, in the step S4), the thickness of the tungsten carbide surface layer is not less than 70% of the thickness of the composite coating, and the powder feeding amount of the spraying is 75-85 g/min; the tungsten carbide powder adopted is 5-38 μm WC-12 Ni.
The tungsten carbide powder can be non-magnetic tungsten carbide powder such as WC-12Co, WC-17Co or WC-12Ni,
the WC-12Ni tungsten carbide powder adopts a nickel base as a bonding agent, has more compatibility with the nickel base self-melting alloy of the transition bottom layer, and can be better fused with the nickel base self-melting alloy of the transition bottom layer in the remelting process; the tungsten carbide powder with the particle size of 5-38um can obtain the best melting effect in the spraying process of the HVAF supersonic speed spray gun, and can avoid the phenomena of non-melting or over-melting.
The tungsten carbide powder with the particle size of 5-38 mu m is selected, the particle size of the tungsten carbide powder is smaller than that of the nickel-based self-fluxing alloy powder, and the distribution uniformity of the tungsten carbide powder in the composite coating can be improved through the matching of the tungsten carbide powder and the nickel-based self-fluxing alloy powder, so that the wear resistance of the composite coating is improved.
The thickness of the tungsten carbide surface layer is set to be more than 70% of the thickness of the composite coating, and the grinding removal amount of at least 20% of the thickness of the composite coating is reserved.
Preferably, in step S5), a lihua LHA-70kw high-frequency induction heating system is adopted, argon gas is used as a protective atmosphere, the flow rate of the argon gas is 40l/min, the oscillation frequency is 48kHz, the oscillation current is 950A, the moving speed is 200mm/min, and the surface roughness of the workpiece to be processed is ra 2.5-3.0.
The temperature is controlled by the set remelting parameters, frequency, current, heating time and moving speed of the coil during heating remelting, protective atmosphere can be formed in an induction heating remelting area by injecting inert gas, the surface of the composite coating is blown and cooled in the inert gas injection process, and the surface temperature of the composite coating can be effectively controlled to be not more than 500 ℃.
Preferably, in step S5), the thickness of the composite coating is 0.2-0.25 mm.
On the basis of ensuring the wear resistance which needs to be improved, the thickness of the composite coating forming the metallurgical bonding transition layer is controlled to be 0.2-0.25mm, so that the total grinding amount is controlled to be less than 0.1mm, the processing amount of the composite coating which needs to be ground is reduced, and the increase of the production cost is favorably avoided.
Preferably, in step S6), the boring and milling process is performed at a milling linear speed of 150 m/min, a feeding speed of 120mm/min, and a milling amount per time of not more than 0.03mm, and at least three times of milling are performed to meet the process requirements.
The grinding linear velocity of processing is controlled and grinding is divided into multiple times, so that the overhigh temperature of a workpiece in the processing process can be avoided, and the abrasion resistance of the composite coating is prevented from being damaged.
Preferably, in step S6), in step S6), the microhardness HV0.3 of the composite coating is greater than 900, the porosity of the composite coating is less than 1%, and the thickness of the composite coating remaining after processing is not less than 0.2 mm.
The porosity of the composite coating is less than 1%, and the composite coating has good compactness; the surface hardness HV0.3 of the composite coating is larger than 900, and the thickness of the composite coating is larger than 0.2mm, so that the pressure chamber and the injection head coated with the composite coating have better wear resistance and service life than the chamber and the injection head coated with the nitride layer.
Examples
1. Selecting a pressing chamber and a matched injection head of a die casting machine, wherein the outer diameter of the pressing chamber is 300mm, the inner hole diameter is 180mm, and the length of the pressing chamber is 1050mm, and processing the pressing chamber and the matched injection head to improve the service lives of the corresponding pressing chamber and the injection head, and the method comprises the following steps:
s1) plugging a feed inlet of a pressure chamber to be processed, carrying out boring and grinding processing on two surfaces to be processed of the pressure chamber and an injection plunger by adopting a YM-200 honing machine, and removing the surface layer of the surface to be processed to form a processing surface by boring and grinding;
s2) carrying out sand blasting on the machined surface by adopting a supersonic flame spraying process to form a sand blasting surface, baking the sand blasting surface by using supersonic flame, and then cleaning the sand blasting surface by using compressed air to form a roughened surface;
s3) spraying nickel-based self-fluxing alloy powder on the two coarsening surfaces of the pressure chamber and the injection plunger respectively by using an excircle spray gun and an inner hole spray gun of the supersonic flame spraying system, and forming a self-fluxing alloy bottom layer above the coarsening surfaces;
s4) continuously spraying tungsten carbide powder on the surface of the self-fluxing alloy bottom layer by using an excircle spray gun and an inner hole spray gun to prepare a tungsten carbide surface layer;
s5) heating and remelting the self-fluxing alloy bottom layer by using a high-frequency induction heating system, enabling the self-fluxing alloy bottom layer, the substrate and the tungsten carbide surface layer to generate metallurgical bonding to form a metallurgical bonding transition layer, and naturally cooling to obtain a standby workpiece with the surface covered with a composite coating;
s6) adopting a honing machine to bore and grind the metallurgical bonding transition layers of the two standby workpieces into matched sizes, namely manufacturing a pressure chamber and an injection plunger covered with the composite coating;
step S1), before boring and grinding, wrapping and protecting the area outside the surface to be processed by a tool made of a galvanized sheet iron, sealing a feed inlet of a pressure chamber by adopting spot welding, and then cleaning the pressure chamber and an injection head by using a Deconex HT170 cleaning agent for 10min respectively through ultrasonic; the thickness of the surface layer removed by boring and grinding is 0.2 mm;
in the step S2), the sand powder for sand blasting is alumina powder with the fineness of 150-220 meshes, the air pressure of compressed air is 0.6MPa, and the powder feeding amount of sand blasting is 95-105 g/min;
in the step S3), the thickness of the self-fluxing alloy bottom layer is 0.9mm, the nickel-based self-fluxing alloy powder is 300-400-mesh Ni60CuMo powder, and the powder feeding amount of spraying is 48-50 g/min;
in the step S4), the thickness of the tungsten carbide surface layer is 0.16mm, and the powder feeding amount of spraying is 75-85 g/min; the adopted tungsten carbide powder is 5-38 mu m WC-12 Ni;
in the step S5), a Lihua LHA-70kw high-frequency induction heating system is adopted, argon is used as a protective atmosphere, the flow rate of the argon is 40l/min, the oscillation frequency is 48kHz, the oscillation current is 950A, the moving speed is 200mm/min, the surface roughness of the standby workpiece is Ra2.5-3.0, and the thickness of the composite coating is 0.25 mm;
in the step S6), the grinding linear speed of boring and grinding is 150 m/min, the feeding speed is 120mm/min, grinding is carried out for three times, the grinding amount of the three times is 0.02mm, 0.02mm and 0.01mm in sequence, and the thickness of the composite coating left after the boring and grinding is 0.2 mm.
2. The microhardness of the press chamber covered with the composite coating was measured using a vickers hardness tester, and the microhardness HV0.3 value was determined to be 945, with a porosity of 0.78%.
The service life of the pressure chamber coated with the composite coating is 5 ten thousand times, the service life of the corresponding injection head coated with the composite coating is 1 ten thousand times, the service life of the injection head is prolonged by 2-3 times compared with that of a nitriding layer, the production efficiency of a die casting machine is obviously improved, and the composite coating has good economy.
3. The composite coating on the surface of the pressure chamber of the example was examined by an optical microscope, and the obtained picture of the metallographic structure is shown in fig. 1, and the microscope image of the composite coating at 100-fold magnification is shown in fig. 2.
FIG. 1 shows a metallographic structure under an optical microscope of a composite coating according to an embodiment of the invention. As can be seen from FIG. 1, the remelted transition bottom layer forms a smooth metallurgical bond with the substrate, and realizes infiltration with the tungsten carbide surface layer; as can be seen from the figure 2 amplified by 100 times, the tungsten carbide hard particles are uniformly fused in the coating, the burning loss and over-melting phenomenon does not occur, and the wear resistance and corrosion resistance of the composite coating are ensured.
In summary, the method for improving the service life of the pressure chamber and the injection head of the die-casting machine by using the composite coating comprises the steps of preparing the composite coating with metallurgical bonding characteristics on the surfaces of the workpiece of the pressure chamber and the injection head by using thermal spraying and induction heating technologies, spraying the nickel-based self-fluxing alloy by using the supersonic spraying technology, preparing the self-fluxing alloy bottom layer with uniform distribution and controllable thickness on the surface of the workpiece, spraying the tungsten carbide powder by using the high-energy supersonic spraying technology, forming the high-density tungsten carbide surface layer on the surface of the self-fluxing alloy bottom layer, and finally remelting the nickel-based self-fluxing alloy layer from the inside of the workpiece by using the induction heating remelting technology, so that the tungsten carbide is prevented from being carbonized at high temperature, the nickel-based self-fluxing alloy layer, the matrix of the workpiece and the tungsten carbide coating on the surface of the workpiece form the metallurgical bonding transition layer with high bonding force and high wear resistance, and the prepared composite coating on the pressure chamber and the injection head has good fatigue resistance, fatigue performance, The hardness is high, the thickness can be processed according to the requirement, and the service life of a pressure chamber and an injection head of the die-casting machine can be obviously prolonged.
In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
The technical principle of the present invention is described above in connection with specific embodiments. The description is only intended to explain the principles of the invention; and should not be construed as limiting the scope of the invention in any way. Based on the explanations herein; other embodiments of the invention will occur to those skilled in the art without the need for inventive faculty; all of which fall within the scope of the present invention.
Claims (9)
1. The method for prolonging the service life of the pressure chamber and the injection head of the die-casting machine by using the composite coating is characterized by comprising the following steps:
s1) plugging a feed inlet of a pressure chamber to be processed, defining two contact surfaces of the pressure chamber and an injection plunger as surfaces to be processed during operation, carrying out boring and grinding processing on the two surfaces to be processed by adopting a honing machine, and removing the surface layer of the surface to be processed by boring and grinding to form a processing surface;
s2) carrying out sand blasting on the processing surface by adopting a supersonic flame spraying process to form a sand blasting surface, baking the sand blasting surface by using supersonic flame, and then cleaning the sand blasting surface by using compressed air to form a roughened surface;
s3) spraying nickel-based self-fluxing alloy powder on the roughened surfaces of the injection plunger and the pressure chamber respectively by using an excircle spray gun and an inner hole spray gun of the supersonic flame spraying system, and forming a self-fluxing alloy bottom layer above the roughened surfaces;
s4) continuously spraying tungsten carbide powder on the surface of the self-fluxing alloy bottom layer by using an excircle spray gun and an inner hole spray gun to prepare a tungsten carbide surface layer;
s5) heating and remelting the self-fluxing alloy bottom layer by using a high-frequency induction heating system, enabling the self-fluxing alloy bottom layer, the substrate and the tungsten carbide surface layer to generate metallurgical bonding to form a metallurgical bonding transition layer, and naturally cooling to obtain a standby workpiece with the surface covered with a composite coating;
s6) adopting a honing machine to bore and mill the metallurgical bonding transition layers of the two standby workpieces into matched sizes, namely manufacturing a pressure chamber and an injection plunger which are covered with the composite coating.
2. The method for improving the service life of a pressure chamber and an injection head of a die casting machine by using a composite coating according to claim 1, wherein in the step S1), before the boring and grinding process, the region outside the surface to be processed is protected by using tool wrapping, a feed port of the pressure chamber is blocked by adopting spot welding, and then the pressure chamber and the injection head are cleaned by ultrasonic for 10min respectively by using a Deconex HT170 cleaning agent.
3. The method for improving the service life of a press chamber and an injection head of a die casting machine by using a composite coating as claimed in claim 1, wherein in the step S2), the sand powder for sand blasting is alumina powder with fineness of 150-220 meshes, the air pressure of compressed air is 0.6MPa, and the powder feeding amount of sand blasting is 95-105 g/min.
4. The method for improving the service life of a pressure chamber and an injection head of a die casting machine by using a composite coating as claimed in claim 1, wherein in step S3), the thickness of the self-fluxing alloy bottom layer does not exceed 50% of the thickness of the composite coating, the nickel-based self-fluxing alloy powder is 300-400 mesh Ni60CuMo powder, and the powder feeding amount of spraying is 48-50 g/min.
5. The method for improving the service life of a pressure chamber and an injection head of a die casting machine with a composite coating according to claim 1, wherein in step S4), the thickness of the tungsten carbide surface layer is not less than 70% of the thickness of the composite coating, and the powder feeding amount of spraying is 75-85 g/min; the tungsten carbide powder adopted is 5-38 μm WC-12 Ni.
6. The method for improving the service life of a press chamber and an injection plunger of a die casting machine by using a composite coating according to claim 1, wherein in step S5), a lihua LHA-70kw high frequency induction heating system is adopted, argon is used as a protective atmosphere, the flow rate of the argon is 40l/min, the oscillation frequency is 48kHz, the oscillation current is 950A, the moving speed is 200mm/min, and the surface roughness of the standby workpiece is ra 2.5-3.0.
7. The method for improving the service life of a pressure chamber and shot sleeve of a die casting machine with a composite coating according to claim 1 wherein in step S5) said composite coating has a thickness of 0.2 to 0.25 mm.
8. The method for improving the service life of a press chamber and an injection head of a die casting machine by using the composite coating as claimed in claim 1, wherein in the step S6), the grinding linear speed of the boring and milling process is 150 m/min, the feeding speed is 120mm/min, the grinding amount per time is not more than 0.03mm, and at least three times of grinding are carried out to meet the process requirements.
9. The method for improving the service life of a pressure chamber and shot sleeve of a die casting machine with a composite coating according to claim 1 wherein in step S6) the microhardness HV0.3 of said composite coating is greater than 900, the porosity of said composite coating is less than 1%, and the thickness of said composite coating remaining after machining is not less than 0.2 mm.
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Effective date of registration: 20221021 Address after: 528225 Room 101, 1st Floor, Building 77, Accelerator Project, Lihe Technology Industry Center, No. 33, Information Avenue South, Shishan Town, Nanhai District, Foshan City, Guangdong Province Applicant after: Guangdong Yueke New Material Technology Co.,Ltd. Applicant after: Foshan Taoyuan Advanced Manufacturing Research Institute Address before: 528225 Room 101, 1st Floor, Building 77, Accelerator Project, Lihe Technology Industry Center, No. 33, Information Avenue South, Shishan Town, Nanhai District, Foshan City, Guangdong Province Applicant before: Guangdong Yueke New Material Technology Co.,Ltd. |