CN108889924B - Short-flow precision casting method for ferromagnetic alloy vacuum casting - Google Patents
Short-flow precision casting method for ferromagnetic alloy vacuum casting Download PDFInfo
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Abstract
The invention provides a ferromagnetic alloy vacuum casting short-flow precision casting method for improving the internal metallurgical quality of a casting and shortening the investment casting process flow, which has no dewaxing and pouring processes, adopts a process method combining shell preparation and casting molding and integrating alloy casting and casting molding, obtains the casting by using the prepared shell as a casting alloy crucible and utilizing a high-frequency vacuum induction furnace to inductively heat and melt a ferromagnetic alloy in the shell for casting molding, reduces the traditional investment casting production process, shortens the casting process flow and the casting production period, improves the production efficiency, saves energy and reduces the consumption, improves the casting quality and improves the casting yield.
Description
Technical Field
The invention belongs to the technical field of precision casting, and particularly relates to a ferromagnetic alloy vacuum casting short-flow precision casting method for shell preparation, alloy smelting and mold filling solidification, which is a casting process method for improving the internal metallurgical quality of a casting, shortening the investment casting process flow, compounding shell preparation and casting molding and integrating alloy casting and casting molding.
Background
Investment casting is a near net shape forming process and is the most common casting method for producing precision castings. Investment casting is a precision casting method in which a pattern is made of an easily fusible material, a plurality of layers of refractory materials are coated on the easily fusible pattern, the pattern is melted and removed after hardening and drying to form a shell, and the shell is baked at a high temperature and then poured to obtain a casting. Investment casting is also called lost wax casting, wax mold manufacturing and investment dewaxing are indispensable production procedures of investment casting, the wax mold is easy to deform in the processes of demolding, transportation, assembly welding and mold shell preparation due to low strength, investment dewaxing easily causes mold shell cracks, the casting quality is directly influenced, and even the mold shell is scrapped in severe cases.
The precise castings of the nickel-based alloy impeller and the like are produced by an investment casting method, the casting process flow is long, the production processes are multiple, the investment casting method relates to the procedures of manufacturing a wax mould, coating and sanding to manufacture a mould shell, hardening and drying the mould shell, dewaxing the investment mould, roasting the mould shell, smelting the alloy, pouring and filling the mould, cooling and solidifying, removing the mould shell, cleaning the mould shell, finishing the castings and the like, the mould shell needs to be poured and filled at a high temperature, otherwise, the mould shell is easy to crack or even burst under the action of the heat impact of high-temperature molten metal, the castings have the defect of insufficient pouring, the alloy smelting and pouring filling have the problems of oxidation burning loss and air suction, the internal metallurgical quality of the castings is directly influenced, the castings have the defects of inclusion.
Z L200310103188.4 discloses a precision casting technique for making high-strength hard mould shell by using foamed plastic mould, foaming and curing the foamed plastic polystyrene to make foamed plastic mould, making shell, roasting, cleaning high-strength mould shell, pouring and filling to complete the production of casting, simplifying production procedure, shortening period for making mould shell and reducing production cost, Z L201410274926. X discloses a method for making integral shell mould by using mould shell roasted mould sample to gasify and burn, using the plastic mould sample made by injection moulding method to substitute wax mould to prepare mould shell, then roasting obtained mould shell to obtain integral shell mould shell, finally cleaning and pouring obtained shell mould shell to obtain casting.
Although the investment casting and the lost foam casting are organically combined by the two precise methods, the dewaxing procedure of the investment casting is saved in the process, the metal solution is injected into the mould shell or the shell mould at high temperature, otherwise, the mould shell or the shell mould is easy to crack or even burst under high-temperature metal thermal shock, the problems of oxidation burning loss and air suction in the alloy smelting and pouring process cannot be solved, the problem of liquid alloy temperature loss exists in the pouring and filling process, and the internal metallurgical quality of a casting cannot be effectively improved. Therefore, a casting process method with high metallurgical quality requirement in precision castings such as nickel-based alloy impellers needs to be developed.
Disclosure of Invention
The invention aims to provide a ferromagnetic alloy precision casting method for improving the internal metallurgical quality of a casting and shortening the investment casting process flow, and aims to provide a casting process method combining shell preparation and casting molding technology and integrating alloy casting and casting molding, wherein a high-frequency vacuum induction furnace is used for inductively heating and melting a ferromagnetic alloy, the prepared shell for casting molding is used as a crucible, the casting is obtained by heating the melting alloy in the shell through the high-frequency vacuum induction furnace, the traditional casting and pouring process is omitted, the problems of shell cracking and liquid alloy temperature loss caused by pouring and filling are avoided, the problems of oxidation burning loss and air suction in the alloy melting and pouring process are solved, the investment casting production process is reduced, the energy is saved, the consumption is reduced, the insufficient pouring, the inclusion and pore defects are obviously reduced, and the inherent metallurgical quality of the casting is improved.
In order to achieve the purposes of improving the internal metallurgical quality of a precise casting and shortening the investment casting process flow, the invention provides a ferromagnetic alloy vacuum casting short-flow precise casting method without dewaxing and pouring processes, which comprises the following steps:
step 1, designing and manufacturing a mold forming and processing mold according to a casting process scheme and a selected easily-gasified and combustible mold material;
step 2, manufacturing a plastic model by using an easily gasified and combustible material by adopting an injection molding method;
step 3, assembling the plastic pattern obtained in the step 2 into an integral pattern according to the design requirements of the casting process;
step 4, selecting proper binder, refractory material and other shell materials according to the technical conditions of the casting shape structure, the casting alloy and the like to prepare surface layer slurry and back layer slurry, and using the integral pattern obtained in the step 3 to replace a wax pattern to prepare a formwork by using the traditional investment casting process, namely obtaining the formwork by coating, sanding, drying and hardening;
step 5, determining the heating temperature-rising speed, the roasting temperature and time, and the shell cooling speed and the cooling mode according to the pattern material and the casting structure shape, controlling the roasting temperature to be 1100-1200 ℃ and the roasting time to be 5-10 min, roasting the shell mold obtained in the step 4 in a resistance furnace, and obtaining the shell mold by utilizing the gasification combustion disappearance of the pattern;
step 6, cleaning and inspecting the shell obtained in the step 5, and after the inspection is ensured to be qualified, filling the alloy for casting molding weighed according to the process requirements into the shell;
and 7, placing the shell filled with the alloy into a high-frequency vacuum induction furnace for induction heating and casting to obtain a casting.
The ferromagnetic alloy precision casting method provided by the invention has the obvious advantages that the casting process method combining the shell preparation and casting molding technology and integrating the alloy casting and casting with casting molding is adopted, dewaxing and casting processes are avoided, the casting process flow is shortened, energy is saved, the material consumption is reduced, the casting quality is improved, and the casting yield is improved. In the production process of a casting, on one hand, a plastic pattern is used for replacing a wax pattern to prepare a mould shell by utilizing the traditional process method of investment casting, and the mould shell is obtained by roasting the mould shell, so that the problem of deformation of the pattern in the processes of demoulding, transportation, assembly and mould shell preparation can be effectively solved, and the problem of mould shell cracks caused by dewaxing of an investment pattern is avoided; on the other hand, the ferromagnetic alloy can be heated and melted by induction in the high-frequency vacuum induction furnace, the prepared shell for casting molding is used as a crucible, and the casting is obtained by casting and molding the prepared casting in the shell by heating and melting the alloy in the high-frequency vacuum induction furnace, so that the traditional casting and pouring process is avoided, the problems of shell cracking and liquid alloy temperature loss caused by casting and filling are avoided, and the problems of oxidation burning loss and air suction in the alloy smelting and pouring process are solved.
The casting method provided by the invention is a ferromagnetic alloy vacuum casting short-flow precision casting method without dewaxing and pouring processes. The new casting process method can improve the internal metallurgical quality of the casting, reduce investment casting production procedures, shorten the production period of the casting, avoid the problems of easy deformation of an investment casting wax mould and temperature loss of poured liquid alloy, solve the problems of oxidation burning loss, air suction and shell cracking caused by pouring and filling in the process of alloy smelting and pouring, save energy, reduce consumption and reduce materials, improve the quality of the casting, obviously reduce the defects of insufficient pouring, inclusion and pores, and is particularly suitable for producing ferromagnetic alloy precision castings such as nickel-based alloy impellers with high requirement on the internal metallurgical quality of the casting.
Drawings
FIG. 1 is a schematic flow chart of the short-flow precision casting method for vacuum casting of ferromagnetic alloy according to the present invention.
Detailed Description
In order to better understand the technical content of the invention, the invention is further explained below with reference to specific examples.
Referring to fig. 1, the present invention aims to improve the internal metallurgical quality of a casting and shorten the investment casting process flow, and provides a novel ferromagnetic alloy precision casting method, which is a casting process method combining shell preparation and casting molding technology and integrating alloy casting and casting molding.
As shown in fig. 1, the present invention provides a method for casting ferromagnetic alloy in vacuum without dewaxing and without casting process, which comprises the following steps:
step 1, designing and manufacturing a mold forming and processing mold according to a casting process scheme and a selected easily-gasified and combustible mold material;
step 2, manufacturing a plastic model by using an easily gasified and combustible material by adopting an injection molding method;
step 3, assembling the plastic pattern obtained in the step 2 into an integral pattern according to the design requirements of the casting process;
step 4, selecting proper binder, refractory material and other shell materials according to the technical conditions of the casting shape structure, the casting alloy and the like to prepare surface layer slurry and back layer slurry, and using the integral pattern obtained in the step 3 to replace a wax pattern to prepare a formwork by using the traditional investment casting process, namely obtaining the formwork by coating, sanding, drying and hardening;
step 5, determining the heating temperature-rising speed, the roasting temperature and time, and the shell cooling speed and the cooling mode according to the pattern material and the casting structure shape, controlling the roasting temperature to be 1100-1200 ℃ and the roasting time to be 5-10 min, roasting the shell mold obtained in the step 4 in a resistance furnace, and obtaining the shell mold by utilizing the gasification combustion disappearance of the pattern;
step 6, cleaning and inspecting the shell obtained in the step 5, and after the inspection is ensured to be qualified, filling the alloy for casting molding weighed according to the process requirements into the shell;
and 7, placing the shell filled with the alloy into a high-frequency vacuum induction furnace for induction heating and casting to obtain a casting.
The scheme has remarkable advantages in preparing ferromagnetic alloy castings, the process does not have the traditional casting and pouring process, the problems of shell cracking and liquid alloy temperature loss caused by pouring and filling are solved, the problems of oxidation burning loss and air suction in the alloy smelting and pouring process are solved, the investment casting production process is reduced, energy is saved, the consumption is reduced, the material is reduced, the defects of insufficient pouring, impurities and pores are obviously reduced, and the inherent metallurgical quality of the castings is improved.
The following embodiments of the present invention take an automotive turbocharger turbine wheel as an example, and describe the implementation of the above process more specifically, but the type of the casting is not limited thereto, and the invention is not limited thereto, and the implementation may adopt a corresponding production process according to the size, shape and structure of the precision casting and the difference of the casting alloy.
[ EXAMPLES one ]
The method for trial production of the turbine impeller of the automobile turbocharger, such as the J130B turbine impeller, by utilizing the ferromagnetic alloy vacuum casting short-flow precision casting method comprises the following steps:
step 1, determining a casting process scheme according to the shape and structure of an impeller, uniformly distributing 3 pieces of I-shaped material at 120 degrees on the same horizontal plane, designing and manufacturing a mould forming and processing mould by using a mould material made of polypropylene.
And 2, manufacturing a cylindrical charging cavity model, a casting forming injection port model and an impeller casting model by using polystyrene through an injection molding method, wherein the charging cavity model and the injection port model are integrally injection molded.
And 3, assembling the cylindrical charging cavity pattern, the casting forming injection opening pattern and the impeller casting pattern into an integral pattern according to the process design requirements and finishing.
Step 4, after the whole pattern is assembled, dip-coating surface layer slurry, throwing slurry, scattering surface sand and drying for 26-28 hours in sequence, and thus manufacturing a surface layer; after the surface layer is dried, dip-coating back layer slurry, sanding and drying for 6-8 hours, and repeating for 2 times to manufacture a back layer and a back two layer; and then sealing slurry, wherein the sealing slurry adopts back layer slurry, the vermiculite powder is scattered after the sealing slurry is soaked, the time is controlled to be 2 min-3 min, and then the sealing slurry is dried for 36-40 h. Wherein, the surface layer slurry refractory material adopts zircon powder and fused quartz powder which are proportioned according to the mass ratio of 5:2, the binder is silica sol, the surfactant adopts paper pulp, and the defoaming agent is silicon resin; the surface sand is made of the same refractory material as the surface layer slurry; the back layer slurry refractory material is mullite powder, the binder is diluted by silica sol and proper amount of distilled water, and the mixture is stirred in a slurry dipping machine for 24 hours for standby; the back sand is made of refractory material consistent with the back layer slurry.
And 5, after the mould shell is fully dried and hardened, placing the mould shell into a resistance furnace for roasting to prepare the mould shell, wherein the roasting heating temperature rise speed is controlled to be 60-80 ℃/h, the roasting temperature is 1150 ℃, the roasting time is controlled to be 8min, and the mould shell after roasting is taken out of the furnace and cooled to 600 ℃ along with the furnace.
And 6, cleaning a cavity and inspecting the quality of the shell, and filling the weighed nickel-based alloy into the shell after ensuring no crack, clean cavity and no residue.
And 7, placing the charging shell into a high-frequency vacuum induction furnace for heating and casting, and cooling and solidifying the alloy to obtain a casting.
Finally, casting quality inspection such as shell shaking, sand blasting cleaning, fluorescence flaw detection and the like is sequentially carried out.
[ example two ]
The automobile turbocharger turbine wheel J130B is produced by investment casting in a conventional manner, comprising the steps of:
step 1, determining a casting process scheme according to the shape and structure of an impeller, uniformly distributing 3 pieces in a first mould at the same horizontal plane position in an angle of 120 degrees, designing a pouring system, manufacturing a wax mould by using medium-temperature wax, and designing and manufacturing a wax mould forming mould.
And 2, manufacturing a pouring cup, a sprue, an ingate and a casting wax mold by using medium-temperature wax.
And 3, assembling and welding the sprue cup, the sprue, the ingate and the impeller casting mold into an integral wax mold group and finishing according to the design requirements of the casting process.
Step 3, dip-coating surface layer slurry, throwing slurry, scattering surface sand and drying for 26-28 hours on the assembled and welded integral wax mold in sequence to manufacture a surface layer; after the surface layer is dried, dip-coating back layer slurry, sanding and drying for 6-8 hours, and repeating for 2 times to manufacture a first back layer and a second back layer; the sealing slurry adopts back layer slurry, vermiculite powder is scattered after the sealing slurry is soaked, the time is controlled to be 2 min-3 min, and then the sealing slurry is dried for 36-40 h. Wherein, the surface layer slurry refractory material adopts zircon powder and fused quartz powder which are proportioned according to the mass ratio of 5:2, the adhesive is silica sol, the surfactant adopts paper pulp, and the defoaming agent is silicon resin; the surface sand is made of the same refractory material as the surface layer slurry; the back layer slurry refractory material is mullite powder, the binder is silica sol, and a proper amount of distilled water is added for dilution, and the mixture is stirred in a slurry dipping machine for 24 hours for later use; the back sand is made of refractory material consistent with the back layer slurry.
And 5, after the mould shell is fully dried and hardened, putting the mould shell into a dewaxing kettle for carrying out investment dewaxing to obtain a silica sol mould shell, wherein the dewaxing temperature is 170 ℃, and the heat preservation time is 15 min.
And step 6, placing the shell into a resistance furnace for roasting after dewaxing, controlling the roasting heating temperature rise speed to be 60-80 ℃/h, the roasting temperature to be 1150 ℃, controlling the roasting time to be 8min, and cooling the roasted shell to 600 ℃ along with the furnace, and discharging and air cooling.
And 7, cleaning the cavity of the shell and inspecting the quality of the shell to ensure that the shell has no crack, the cavity is clean and no residue.
And 8, smelting the alloy, roasting the shell to 1150-1200 ℃ to ensure that casting is carried out at high temperature, obtaining a casting after the cast alloy is cooled and solidified, and then carrying out casting quality inspection such as shell shaking, sand blasting cleaning, fluorescent flaw detection and the like in sequence.
[ EXAMPLE III ]
The method for trial-producing the turbine impeller of the automobile turbocharger, such as the K418super alloy SJ50 turbine impeller, by utilizing the ferromagnetic alloy vacuum fusion casting short-flow precision casting method comprises the following steps:
step 1, determining a casting process scheme according to the shape and structure of an impeller, wherein 6I-shaped castings are distributed on two different horizontal plane positions, 3I-shaped castings on each horizontal plane position are uniformly distributed at 120 degrees, the castings on the two different horizontal plane positions are arranged in a 60-degree crossed mode, a pattern material is polyethylene, and a pattern forming and processing mold is designed and manufactured.
And 2, manufacturing a cylindrical charging cavity model, a casting forming injection port model and an impeller casting model by using polyethylene through an injection molding method, wherein the charging cavity model and the injection port model are integrally injection molded.
And 3, assembling the cylindrical charging cavity pattern, the casting forming injection opening pattern and the impeller casting pattern into an integral pattern according to the process design requirements and finishing.
Step 4, after the whole pattern is assembled, dip-coating surface layer slurry, throwing slurry, scattering surface sand and drying for 22-25 hours in sequence to manufacture a surface layer; after the surface layer is dried, dip-coating back layer slurry, sanding and drying for 5-7 hours, and repeating for 2 times to manufacture a first back layer and a second back layer; the sealing slurry adopts back layer slurry, vermiculite powder is scattered after the sealing slurry is soaked, the time is controlled to be 2 min-3 min, and then the sealing slurry is dried for 32-36 hours. Wherein, the surface layer slurry refractory material adopts zircon powder and fused quartz powder which are proportioned according to the mass ratio of 6:3, the adhesive is silica sol, the surfactant adopts paper pulp, and the defoaming agent is silicon resin; the surface sand is made of the same refractory material as the surface layer slurry; the back layer slurry refractory material is mullite powder, the binder is silica sol, and a proper amount of distilled water is added for dilution, and the mixture is stirred in a slurry dipping machine for 24 hours for later use; the back sand is made of refractory material consistent with the back layer slurry.
And 5, after the mould shell is fully dried and hardened, placing the mould shell into a resistance furnace for roasting to prepare the mould shell, wherein the roasting heating temperature rise speed is controlled to be 60-80 ℃/h, the roasting temperature is 1100 ℃, the roasting time is controlled to be 6min, and the mould shell after roasting is taken out of the furnace and cooled in air when the temperature is reduced to 600 ℃.
And 6, cleaning a cavity and inspecting the quality of the shell, and filling the weighed K418 superalloyy alloy into the shell after ensuring no crack, clean cavity and no residue.
And 7, placing the charging shell into a high-frequency vacuum induction furnace for heating and casting, and cooling and solidifying the alloy to obtain a casting.
Finally, quality inspection such as shell vibration, sand blasting cleaning, fluorescent flaw detection and the like can be sequentially carried out.
[ EXAMPLE IV ]
The method is characterized in that a traditional mode is adopted to perform investment casting on a turbine wheel K418superalloy SJ50 of the automobile turbocharger, and comprises the following steps:
step 1, determining a casting process scheme according to the shape and structure of an impeller, wherein 6 pieces of I-shaped materials are distributed on two different horizontal plane positions, 3 pieces of I-shaped materials are uniformly distributed at each horizontal plane position at 120 degrees, castings at the two different horizontal plane positions are arranged in a 60-degree crossed mode, a pouring system is designed, a wax mold is made of medium-temperature wax, and a wax mold forming mold is designed and manufactured.
And 2, manufacturing a pouring cup, a sprue, an ingate and a casting wax mold by using medium-temperature wax.
And 3, assembling and welding the sprue cup, the sprue, the ingate and the impeller casting mold into an integral wax mold group and finishing according to the design requirements of the casting process.
Step 4, preparing a formwork by using a traditional process method of investment casting after the whole pattern is assembled, and sequentially carrying out dip-coating of surface layer slurry, slurry throwing, surface sand scattering and drying for 22-25 hours to manufacture a surface layer; after the surface layer is dried, dip-coating back layer slurry, sanding and drying for 5-7 hours, and repeating for 2 times to manufacture a first back layer and a second back layer; the sealing slurry adopts back layer slurry, vermiculite powder is scattered after the sealing slurry is soaked, the time is controlled to be 2 min-3 min, and then the sealing slurry is dried for 32-36 hours. Wherein, the surface layer slurry refractory material adopts zircon powder and fused quartz powder which are proportioned according to the mass ratio of 6:3, the adhesive is silica sol, the surfactant adopts paper pulp, and the defoaming agent is silicon resin; the surface sand is made of the same refractory material as the surface layer slurry; the back layer slurry refractory material is mullite powder, the binder is silica sol, and a proper amount of distilled water is added for dilution, and the mixture is stirred in a slurry dipping machine for 24 hours for later use; the back sand is made of refractory material consistent with the back layer slurry.
And 5, after the mould shell is fully dried and hardened, putting the mould shell into a dewaxing kettle for carrying out investment dewaxing to obtain a silica sol mould shell, wherein the dewaxing temperature is 170 ℃, and the heat preservation time is 15 min.
And 6, placing the shell into a resistance furnace for roasting after dewaxing, controlling the roasting heating temperature rise speed to be 60-80 ℃/h, the roasting temperature to be 1100 ℃, controlling the roasting time to be 6min, and taking the shell out of the furnace for air cooling after the shell is roasted and cooled to 600 ℃ along with the furnace.
And 7, cleaning the cavity of the shell and inspecting the quality of the shell to ensure that the shell has no crack, the cavity is clean and no residue.
And 8, smelting the alloy, roasting the shell to 1150-1200 ℃ to ensure that casting is carried out at high temperature, obtaining a casting after the cast alloy is cooled and solidified, and then carrying out casting quality inspection such as shell shaking, sand blasting cleaning, fluorescent flaw detection and the like in sequence.
In the specific example, two types of automobile turbocharger turbine impellers are produced in batches by respectively adopting the ferromagnetic alloy vacuum casting short-flow precision casting method and the investment casting method, and the production comparison result shows that the process method not only simplifies the production operation, but also obviously improves the casting quality compared with the investment casting. Although the main casting defects of the castings are deformation, insufficient casting, inclusion and pore defects, the rejection rate of the castings produced by the process method is obviously reduced. Table 1 shows the results of the statistics of the rejection rate of the wheel castings in the specific implementation.
TABLE 1 comparison of rejection rates of impeller castings
As can be seen from Table 1, the casting scrap rates of the first and third examples of the present invention are significantly lower than those of the second and fourth conventional investment casting examples, i.e., the casting scrap rate of the first example impeller J130B is reduced by 5.1% and is only 40.7% that of the second example, and the casting scrap rate of the third example impeller SJ50 is only 40.2% that of the fourth example and is reduced by 5.5%.
It can also be seen from table 1 that the scrap rates of the castings of examples one and three are significantly lower than those of examples two and four due to the substantial reduction in casting deformation, undercast casting, inclusions and porosity-type defects. The casting deformation is mainly related to the deformation of a pattern in the processes of demoulding, transporting, assembling and preparing a mould shell, the insufficient casting is the result of the cracking of the mould shell, the inclusion and the pore type waste products of the casting in the first embodiment and the third embodiment are mainly related to the low metallurgical quality of base metal alloy, and the inclusion and the pore type waste products of the casting in the second embodiment and the fourth embodiment are mainly caused by the oxidation burning loss of alloy smelting and the air suction of pouring filling type.
The results show that the casting process method combining shell preparation and casting molding technology and alloy casting and casting molding integration provided by the invention has obvious technical advantages and obtains good technical effect and economic benefit in production application. The plastic pattern is not easy to damage and deform in the processes of demoulding, assembling and preparing the mould shell, so that the problem of casting scrapping caused by wax mould deformation is avoided, the problems of mould shell cracking, air suction and the like caused by alloy smelting oxidation burning loss and pouring filling are solved by integrating alloy casting and casting forming, the internal metallurgical quality of the casting is improved, and the yield of the casting is high.
The technical scheme and the comparative example show that the casting process method combining the shell preparation and fusion casting molding technology is free of dewaxing and casting production operation, shortens the casting process flow, is suitable for producing ferromagnetic alloy precise castings with high requirements on the internal metallurgical quality of nickel-based alloy impellers and the like, is not limited in the structural complexity of the castings, avoids the problems of deformation of the traditional investment casting wax mold in the processes of demolding, transportation, assembly and mold shell preparation and liquid alloy temperature loss in the process of pouring and filling, solves the problems of shell cracking, air suction and the like caused by melting oxidation burning loss of the investment casting alloy, investment dewaxing and pouring and filling, obviously reduces the defects and is high in the casting yield.
In addition, by utilizing the casting process method integrating alloy casting and casting molding, the shell for casting molding is used as a crucible, and the ferromagnetic alloy is melted by induction heating of a high-frequency vacuum induction furnace and is cast and molded in the shell to obtain the casting, so that the problems of oxidation burning loss and air suction easily generated in the alloy smelting and pouring processes of investment casting are solved, the inclusion and pore defects of the casting are obviously reduced, and the internal metallurgical quality of the casting is improved.
Meanwhile, a casting process method combining shell preparation and casting molding and integrating alloy casting and casting molding is adopted, so that the production process is simplified, energy and material consumption are reduced, the casting quality is improved, and the method is suitable for producing ferromagnetic alloy precision castings with high requirement on metallurgical quality in the castings.
The defects of insufficient pouring, inclusion and pores are obviously reduced, and the dimensional precision, the internal metallurgical quality and the surface quality of the casting are obviously improved compared with the traditional investment casting.
Claims (5)
1. A short-process precision casting method for a ferromagnetic alloy vacuum casting nickel-based alloy impeller is characterized by comprising the following steps:
step 1, determining to manufacture a mold forming processing mold according to a casting process scheme and a selected easily-gasified and combustible mold material;
step 2, manufacturing a plastic model by using an easily gasified and combustible material by adopting an injection molding method;
step 3, assembling the plastic model obtained in the step 2 into an integral model;
step 4, determining a formwork material according to the shape and the structure of the casting and the casting alloy, preparing a surface layer and a back layer, and preparing the formwork by using the integral pattern obtained in the step 3 to replace a wax pattern by using the traditional investment casting process, namely obtaining the formwork by coating, sanding and drying and hardening;
step 5, determining the heating temperature-rising speed, the roasting temperature and time, and the shell cooling speed and the cooling mode according to the pattern material and the casting structure shape, roasting the shell mold obtained in the step 4 in a resistance furnace, and obtaining the shell mold by utilizing the gasification combustion disappearance of the pattern;
step 6, cleaning and inspecting the shell obtained in the step 5, and after the inspection is ensured to be qualified, filling the alloy for casting molding weighed according to the process requirements into the shell;
and 7, placing the shell filled with the alloy into a high-frequency vacuum induction furnace for induction heating and casting to obtain a casting.
2. The method for short-process precision casting of the ferromagnetic alloy vacuum casting nickel-based alloy impeller according to claim 1, wherein in the step 5, the roasting temperature is controlled to be 1100-1200 ℃ and the roasting time is controlled to be 5-10 min.
3. The method for short-process precision casting of a ferromagnetic alloy vacuum casting nickel-based alloy impeller according to claim 1, wherein in the step 4, the mold shell materials of the surface layer and the back layer comprise: the surface layer slurry refractory material is prepared from zircon powder and fused quartz powder according to the mass ratio of 6:3, the binder is silica sol, the surfactant is paper pulp, the defoaming agent is silicone resin, and the surface sand is the same as the surface layer slurry refractory material; the back layer slurry refractory material is mullite powder, the binder is diluted by silica sol and proper amount of distilled water, and the mixture is stirred in a slurry dipping machine for 24 hours for standby; the back sand is made of refractory material consistent with the back layer slurry.
4. The method for short-run precision casting of a ferromagnetic alloy vacuum-cast ni-based alloy impeller according to claim 3, wherein in the step 2, a cylindrical charging cavity pattern, a casting forming sprue pattern and an impeller casting pattern are manufactured from polyethylene by an injection molding method, and the charging cavity pattern and the sprue pattern are integrally injection-molded.
5. The method for short-run precision casting of a ferromagnetic alloy vacuum-cast ni-based alloy impeller according to claim 4, wherein in step 3, the cylindrical charge cavity pattern, the casting-forming sprue pattern and the impeller casting pattern are assembled into an integral pattern and trimmed.
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| CN110479957A (en) * | 2019-07-29 | 2019-11-22 | 山东燕山精密机械有限公司 | Evaporative pattern shell and preparation method thereof |
| CN111545710A (en) * | 2020-05-13 | 2020-08-18 | 南京工程学院 | Technological method and system for precisely casting refined grains and tissues of nickel-based superalloy |
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| SU973213A2 (en) * | 1980-05-29 | 1982-11-15 | Харьковский Ордена Ленина И Ордена Октябрьской Революции Моторостроительный Завод "Серп И Молот" | Injection die |
| CN101590513B (en) * | 2009-07-03 | 2011-04-27 | 郑州神牛铸造有限公司 | Method for precise composite casting evaporative pattern |
| CN103949590B (en) * | 2014-05-12 | 2016-06-29 | 西北工业大学 | A kind of oxide doped and modified Y2O3The preparation method of+YSZ is high temperature resistant shell |
| CN104014748B (en) * | 2014-06-19 | 2016-11-23 | 南京工程学院 | The method utilizing the overall shell mould of formwork roasting apperance gasification, and combustion preparation |
| CN107216156A (en) * | 2017-05-12 | 2017-09-29 | 上海大学 | MgAl2O4‑SrZrO3Composite shell, using and preparation method thereof |
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