Metal piece and method for casting thereof

Abstract

The application relates to a metal piece and a casting method thereof. The casting method of the metal piece comprises the following steps: obtaining a wax mold module, wherein the wax mold module comprises a casting wax mold and a pouring wax mold connected with the casting wax mold; wherein the pouring gate in the pouring wax mold is in the shape of a sandglass, and the height is 20mm-50mm; the wax mold module is subjected to slurry sticking and sand hanging to form a mold shell on the surface of the wax mold module; the wax mold module is removed; the molten metal liquid is subjected to deoxidization and deslagging, and a protective gas is introduced from the side of a container carrying the molten metal liquid at a flow rate of 400L / min-500L / min; the molten metal liquid after deoxidization and deslagging is poured into the mold shell after the wax mold module is removed, so that the molten metal liquid fills the mold shell, is cooled and formed, and a metal piece is obtained. The casting method of the metal piece is beneficial to improving surface defects and improving cleanliness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of casting, in particular to a metal piece and a casting method thereof. BACKGROUND

[0002] Metal, for example, stainless steel, has the advantages of strong corrosion resistance and high strength, and is the main material for special-shaped pieces. However, the structure of special-shaped pieces is complex, and cannot be formed by stamping, welding and other forming methods, and needs to be formed by using the method of investment casting. However, the current stainless steel investment casting pieces still have the following problems: surface defects such as inclusions, cold shut, and porosity, and cannot achieve high cleanliness. SUMMARY

[0003] Therefore, the present application provides a casting method of a metal piece, which is beneficial to improve the surface defects and improve the cleanliness.

[0004] In addition, the present application also provides a metal piece.

[0005] A casting method of a metal piece, comprising the following steps:

[0006] Obtaining a wax mold module, the wax mold module comprising a casting wax mold and a pouring wax mold connected with the casting wax mold; wherein the sprue in the pouring wax mold is in the shape of a sandglass, and the height is 20mm-50mm;

[0007] Slurry and sand are applied to the wax mold module to form a mold shell on the surface of the wax mold module;

[0008] The wax mold module is removed;

[0009] The molten metal liquid is deoxidized and deslagged, and at the same time, a protective gas is introduced from the side of the container carrying the molten metal liquid at a flow rate of 400L / min-500L / min;

[0010] The molten metal liquid after deoxidization and deslagging is poured into the mold shell after the wax mold module is removed, so that the molten metal liquid fills the mold shell, and is cooled and formed to obtain a metal piece.

[0011] Optionally, the maximum width of the sprue is R1, and the minimum width is R2, and R2 / R1 is 0.4-0.6.

[0012] Optionally, the inner wall of the sprue is in the shape of a circular arc.

[0013] Optionally, the protective gas comprises argon.

[0014] Optionally, the protective gas is introduced from the opposite two sides of the container carrying the molten metal liquid.

[0015] Optionally, the molten metal liquid is heated by a medium-frequency induction furnace, opposite sides of the medium-frequency induction furnace are provided with air inlet pipes, and the protective gas is introduced into the molten metal liquid through the air inlet pipes while the molten metal liquid is heated.

[0016] Optionally, the total thickness of the mold shell is 8mm-15mm, and the total number of layers is 5-8.

[0017] Optionally, after the step of removing the wax mold module and before the step of pouring the molten metal liquid, the mold shell is fired at 1100-1200°C for 40-60min.

[0018] Optionally, the mold shell is fired by far infrared rays.

[0019] Optionally, in the step of pouring the deoxidized and deslagged molten metal liquid into the mold shell after removing the wax mold module, the pouring speed is 50-80cm / s.

[0020] Optionally, the wax mold module is prepared by 3D printing.

[0021] Optionally, the metal part includes stainless steel.

[0022] Optionally, the metal part is a special-shaped part.

[0023] Optionally, the area of the metal part is greater than or equal to 50 square decimeters.

[0024] A metal part prepared by the above-mentioned casting method of a metal part.

[0025] The above-mentioned casting method of a metal part optimizes the shape and size of the sprue in the metal part investment casting process, and introduces a certain flow of protective gas from the side, which is beneficial to reduce the surface defects of the cast metal part and improve the cleanliness. Specifically, by using a sandglass-shaped sprue and controlling the height of the sprue, the molten metal liquid flows downward along the inner wall of the sprue during pouring, and the gas in the mold shell moves upward and is discharged, avoiding defects such as shrinkage holes and cold shuts on the surface of the metal part. During the deoxidation and deslagging process of the molten metal liquid, the protective gas is introduced from the side, which is beneficial to form turbulent flow of the molten metal liquid compared to the traditional way of introducing the protective gas from the top or bottom, improve the reaction efficiency of the molten metal liquid with the deoxidizer and deslagging agent, and significantly improve the purity and deoxidation and deslagging effect of the molten metal liquid. At the same time, combined with the precise control of the flow of protective gas, the problems of surface defects such as pores and inclusions caused by excessive disturbance of the molten metal liquid surface or insufficient deoxidation reaction are avoided.

[0026] Therefore, the casting method of the metal piece is beneficial to improve the surface defects of the metal piece and improve the cleanliness by optimizing the process parameters. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 A process flow diagram of the casting method of the metal piece in some embodiments of the present application;

[0029] Figure 2 A structure diagram of the inner wall of the sandglass-shaped gate in some embodiments of the present application is in an arc shape;

[0030] Figure 3 A structure diagram of the inner wall of the sandglass-shaped gate in an arc shape;

[0031] Figure 4 A diagram of introducing protective gas into the molten metal liquid in some embodiments of the present application;

[0032] Figure 5 A process flow diagram of the casting method of the metal piece in some embodiments of the present application;

[0033] Figure 6 A super-depth microscope diagram of the stainless steel piece prepared in Comparative Example 1;

[0034] Figure 7 A photograph of the stainless steel piece prepared in Comparative Example 1;

[0035] Figure 8 A polished appearance diagram of the stainless steel piece prepared in Comparative Example 1. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present application, the present application will be described more fully in conjunction with specific embodiments. In the specific embodiments, the preferred embodiments of the present application are given. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used in the description herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] Unless otherwise defined, or if a contradictory definition is present, the terms or phrases used in the present application have the following meanings:

[0039] In the present application, "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features.

[0040] In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0041] In the present application, "one or more" refers to any one, any two or any two or more of the listed items. Among them, "several" refers to any two or more.

[0042] In the present application, the percentage concentration involved, unless otherwise specified, refers to the final concentration. The final concentration refers to the proportion of the added ingredient in the system after the ingredient is added.

[0043] In the present application, "further", "further", "particularly", "for example", "such as", "example", "for example" are used for the purpose of description, indicating that the technical solutions before and after are related in terms of coverage, but should not be understood as limiting the previous technical solutions, nor should it be understood as limiting the scope of protection herein. In this paper, unless otherwise stated, A (such as B) means that B is one non-limiting example of A, and it can be understood that A is not limited to B.

[0044] In the present application, "optionally", "optional", "optional" means optional, that is, selected from "yes" or "no" two parallel schemes. If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "optional" is independent of each other. In the present application, "optionally contains", "optionally contains" and the like, means "contains or does not contain". "Optional component X" means that component X exists or does not exist, or means that it contains or does not contain the component X.

[0045] When a range of values is disclosed, unless otherwise stated, the endpoints of the ranges are included. The disclosure includes any and all subranges and entire faiths within the ends of this range. Integers within the

[0046] In this application, both open-ended and closed-ended technical features are disclosed. The open-ended technical features include the closed-ended technical solutions consisting of the listed features, and also include the open-ended technical solutions containing the listed features.

[0047] In this application, the terms "comprising" and "having" and any variations thereof are intended to cover the inclusions not exclusions. For example, a process, method, system, product, or apparatus that comprises a list of steps or units is not limited to the listed steps or units, but can optionally further include steps or units not listed, or can optionally further include other steps or components inherent to such processes, methods, products, or apparatuses.

[0048] In this application, the phrase "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0049] In the conventional technology, in order to overcome various defects on the surface of the metal part cast by the investment casting, deoxidizing agents and slag removing agents are mainly added, and the time of the deoxidizing agents and slag removing agents is controlled by experience. The products poured out each time have different defects, such as pores, inclusions, segregation, etc.; especially for special-shaped parts, different parts have different problems. Another conventional technology discloses a casting process for a stainless steel pump shell. By performing multiple sand blasting treatments on the surface of the wax mold, the smoothness of the surface of the finished product can be greatly improved, and the quality of the finished product can be improved. At the same time, a solution and an ammonium chloride solution are added during pouring, so that the stainless steel solution can better adhere to the pores inside the pump shell and carry away the internal floating sand, further improving the precision of the finished product. However, the added ammonium chloride may decompose to produce ammonia (NH3) and hydrogen chloride (HCl) gas at high temperatures. The nascent hydrogen and ammonia dissolved into the molten steel may reach a saturated state when ammonia decomposes, and quickly combine into hydrogen and nitrogen to form a large number of fine bubbles, which will cause more pores and inclusions on the surface of the casting.

[0050] Based on this, some embodiments of the present application provide a casting method of a metal piece, please refer to Figure 1 , comprising the following steps:

[0051] Step S110: obtaining a wax mold module, the wax mold module comprising a casting wax mold and a pouring wax mold connected with the casting wax mold; wherein the pouring gate in the pouring wax mold is in the shape of an hourglass, and the height is 20mm-50mm.

[0052] Step S120: sticking slurry and hanging sand on the wax mold module to form a mold shell on the surface of the wax mold module.

[0053] Step S130: removing the wax mold module.

[0054] Step S140: deoxidizing and deslagging the molten metal liquid, and at the same time, introducing a protective gas from the side of the container carrying the molten metal liquid at a flow rate of 400L / min-500L / min.

[0055] Step S150: pouring the deoxidized and deslagged molten metal liquid into the mold shell after removing the wax mold module, so that the molten metal liquid fills the mold shell, and is cooled and formed to obtain a metal piece.

[0056] In the present application, the pouring gate in the shape of an hourglass refers to the two ends of the pouring gate being large in diameter and the middle being small in diameter, and the middle being the neck.

[0057] In some embodiments, the maximum width of the pouring gate is R1, the minimum width is R2, and R2 / R1 is 0.4-0.6. It can be understood that R2 / R1 refers to the ratio of R2 to R1. For example, R2 / R1 can be but is not limited to 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6 or a range formed by any two of these values. Specifically, the maximum width of the pouring gate corresponds to the diameter of the two ends of the pouring gate, and the minimum width of the pouring gate corresponds to the diameter of the middle of the pouring gate. In one example, the diameters of the two ends of the pouring gate are the same.

[0058] In some embodiments, the inner wall of the pouring gate is in the shape of a circular arc. For example, please refer to Figure 2 , a schematic view of one structure of the pouring gate in the pouring wax mold. In Figure 2 , the downward black arrow indicates the flow direction of the molten metal liquid during pouring, and the upward red arrow indicates the flow direction of the gas during pouring. The present application research finds that the inner wall of the pouring gate is in the shape of a circular arc, on the one hand, the molten metal liquid flows downward along the inner wall of the pouring gate during pouring, and the gas in the mold shell moves upward and is discharged, avoiding defects such as shrinkage cavity and cold shut on the surface of the metal piece, on the other hand, it can also avoid the problem of mold shell rupture and molten metal liquid leakage caused by a large impact of the molten metal liquid on the opposite side during pouring. If the inner wall of the pouring gate is in the shape of a broken line, for example Figure 3As shown, during pouring, the molten metal liquid can directly form an impact on the opposite side from the oblique line at the upper end of the sprue, and the impact force can cause the mold shell to break, thereby causing the molten metal liquid to leak. Therefore, in some embodiments of the present application, preferably, the inner wall of the sprue is arc-shaped.

[0059] In some embodiments, the inner wall of the sprue is smooth to reduce flow resistance.

[0060] The sprue is in the shape of a sandglass, and the height is controlled to be 20mm-50mm to ensure the stability and controllability of the flow of the molten metal liquid. Due to the special design of the sandglass-shaped sprue, the molten metal liquid flows downward along the inner wall of the sprue during the flow process, while the gas in the cavity is moved upward and discharged. Specifically, the bottom of the sprue is enlarged in diameter and provided with an R-angle shunt structure, so that the molten metal liquid can form a vacuum area when flowing through the sprue, promote the gas to be discharged upward from the bottom of the sprue through the middle area, and enhance the gas discharge effect, thereby effectively reducing the porosity and shrinkage defects in the castings.

[0061] If the height of the sprue is lower than 20mm, the molten metal liquid cannot flow downward along the inner wall of the sprue during the subsequent pouring of the molten metal liquid, and a turbulent flow is formed in the sprue, so that the gas in the mold shell cannot move upward and be discharged, which can cause shrinkage holes, cold shuts and other defects on the surface of the castings. If the height of the sprue is higher than 50mm, the height of the middle neck portion is increased, causing necking, and the molten metal liquid forms a turbulent flow in the neck portion, which can also cause the gas in the mold shell to be unable to move upward and be discharged, thereby causing shrinkage holes, cold shuts and other defects on the surface of the castings.

[0062] Exemplarily, the height of the sprue can be, but is not limited to, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 42mm, 45mm, 48mm, 50mm or a range formed by any two of these values.

[0063] In some embodiments, the wax mold module is prepared by 3D printing.

[0064] It can be understood that the casting wax mold is a mold for the subsequent metal part to be made, and the shape of the casting wax mold is the same as that of the metal part to be made. The pouring wax mold is a mold for realizing the pouring of the molten metal liquid. The pouring wax mold includes structures such as sprues and runners. The runner can adopt a structure commonly used in the art. It can be understood that the materials of the casting wax mold and the pouring wax mold can be the same or different, as long as a material commonly used in the art with a low melting point and easy to melt is used.

[0065] In addition, in some other embodiments, the wax pattern assembly can also be obtained by using other processes commonly used in the art, for example, obtaining a casting wax pattern and a pouring wax pattern respectively, and then combining the two to obtain the wax pattern assembly. Such a process can be commonly used in the art, and will not be described in detail herein.

[0066] Specifically, the steps of slurry coating and sanding the wax pattern assembly can be commonly used in the art, for example, using silica sol paint for slurry coating, and using zircon sand for sanding. In some embodiments, the steps of slurry coating and sanding the wax pattern assembly include immersing the wax pattern assembly in silica sol paint to wet the surface of the wax pattern assembly, and coating zircon sand on the surface of the silica sol.

[0067] Further, the shell is multi-layered, and the steps of slurry coating and sanding the wax pattern assembly include immersing the wax pattern assembly in silica sol paint to wet the surface of the wax pattern assembly, coating zircon sand on the surface of the silica sol, and repeating the steps of slurry coating and sanding after air drying to obtain a multi-layered shell.

[0068] In some embodiments, the total number of layers of the shell is 5-8, and the total thickness of the shell is 8-15 mm.

[0069] For example, the total number of layers of the shell can be, but is not limited to, 5, 6, 7, 8, or a range formed by any two of these values. The total thickness of the shell can be, but is not limited to, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, or a range formed by any two of these values.

[0070] By optimizing the number of layers and the thickness of the shell, it is beneficial to further improve the surface defects and increase the cleanliness. Specifically, the number of layers of the shell is 5-8, and the total thickness is 8-15 mm, which is beneficial to increase the structural density of the shell, and more beneficial to effectively resist the impact force and high temperature of the molten metal liquid during casting, thereby reducing the risk of cracking or deformation of the shell during pouring, and making the surface of the shell have a suitable roughness, reducing surface defects, and thereby reducing the risk of sand holes, pores and other defects of the metal part caused by the filling of the molten metal liquid due to the surface defects of the shell. In addition, the number of layers and the thickness of the shell are suitable, which reduces the risk of shrinkage holes, shrinkage and other defects of the metal part caused by the slow cooling speed of the molten metal liquid due to the increase in the thickness of the shell, and is beneficial to the smooth discharge of gas during pouring, thereby reducing the risk of pores and other defects in the cast part.

[0071] In some embodiments, the step of removing the wax pattern assembly is performed in a dewaxing machine. The specific temperature can be adjusted according to the material of the wax pattern, for example, 70-100°C.

[0072] In some embodiments, after the step of removing the wax mold module, and before the step of pouring the molten metal liquid into the mold shell, further comprising: baking the mold shell at 1100-1200°C for 40-60 min. By baking the mold shell, the strength of the mold shell can be improved, and the strength of the mold shell can be reduced and deformed during the subsequent pouring process. Precise control of the baking temperature and time further improves the performance and stability of the mold shell.

[0073] For example, the baking temperature can be, but is not limited to, 1100°C, 1120°C, 1120°C, 1120°C, 1120°C, 1120°C, 1120°C, or a range formed by any two of these values. The baking time can be, but is not limited to, 40 min, 42 min, 44 min, 45 min, 46 min, 48 min, 50 min, 52 min, 54 min, 55 min, 58 min, 60 min, or a range formed by any two of these values.

[0074] Specifically, the mold shell is baked using far infrared rays. Far infrared rays can be uniformly distributed around the mold shell, ensuring that the mold shell is heated in all directions and reducing the risk of defects in subsequent casting due to incomplete baking in some areas of the mold shell. It will be understood that the wavelength range of far infrared rays is typically between 3 μm and 1000 μm.

[0075] In some embodiments, the metal is stainless steel, for example, the metal is 304 stainless steel. The molten metal liquid is obtained by heating the metal at 1670-1690°C. It will be understood that in other embodiments, the metal is not limited to stainless steel, and the melting temperature can be adjusted according to the material of the metal.

[0076] In some embodiments, before the step of pouring the molten metal liquid, further comprising testing the composition of the molten metal liquid, and adding corresponding elemental alloys according to the composition of the molten metal liquid. By testing the composition of the molten metal liquid, and supplementing the corresponding metal elements according to the difference between the composition of the molten metal liquid and the composition of the workpiece to be cast, the chemical composition can be ensured to meet the requirements of the casting process, thereby ensuring the quality of the casting, and avoiding problems such as reduced mechanical properties and reduced corrosion resistance due to uneven composition.

[0077] In some embodiments, the metal is heated by a medium-frequency induction furnace to obtain a molten metal liquid. The medium-frequency induction furnace refers to an induction furnace with a working frequency in the range of 150 Hz to 10,000 Hz, which has the advantages of fast melting speed, high production efficiency, strong adaptability, flexible use, good electromagnetic stirring effect, and easy start-up and operation.

[0078] In some embodiments, the deoxidizing agent and the slag removing agent are added to the molten metal liquid for deoxidization and slag removal. The specific deoxidizing agent and slag removing agent can be commonly used in the art, and are not particularly limited herein. For example, in some embodiments, the primary deoxidizing agent is a manganese alloy, and the final deoxidizing agent is a composite iron alloy.

[0079] The deoxidization and slag removal of the molten metal liquid are performed while the protective gas is introduced from the side of the container carrying the molten metal liquid at a flow rate of 400 L / min to 500 L / min, which is beneficial for better deoxidization, forms a turbulent flow of the molten metal liquid, enables the deoxidizing agent to quickly react with the molten metal liquid, and enables the oxides to quickly float on the surface of the molten metal liquid and be removed by the slag removing agent. Specifically, the protective gas is introduced from the side, which is beneficial for forming a turbulent flow of the molten metal liquid and improving the mixing effect of the molten metal liquid with the deoxidizing agent and the slag removing agent, compared with the conventional way of introducing the protective gas from the top or the bottom. If the flow rate of the protective gas is lower than 400 L / min, the decrease in the turbulent flow intensity directly affects the mixing efficiency between the deoxidizing agent and the molten metal liquid, the deoxidization reaction is not sufficient, and part of the deoxidizing agent cannot effectively contact the oxides in the molten metal liquid, resulting in a high oxygen content in the molten metal liquid and affecting the quality of the final castings. In addition, the dispersion state of the oxides in the molten metal liquid is also poor, which is not conducive to the subsequent slag removal operation, increases the amount of slag, increases the production cost, and can affect the purity of the molten metal liquid. If the flow rate of the protective gas is higher than 500 L / min, it will cause severe disturbance on the surface of the molten metal liquid, and even cause splashing. The excessively high flow rate of the protective gas can also cause the deoxidizing agent to be unevenly distributed in the molten metal liquid, thereby affecting the stability of the deoxidization effect, and also cause the oxides to form smaller particles in the molten metal liquid, which are difficult to be effectively removed by the slag removing agent, and increase the difficulty of slag removal.

[0080] For example, the flow rate of the protective gas can be, but is not limited to, 400 L / min, 420 L / min, 440 L / min, 450 L / min, 460 L / min, 480 L / min, 500 L / min, or a range formed by any two of these values.

[0081] In one example, the protective gas includes argon. It can be understood that in other embodiments, the protective gas is not limited to argon, but can also be other gases, such as helium and other inert gases. The above protective gas not only protects the molten metal liquid from being oxidized, but also does not introduce other elements into the molten metal liquid. In addition, if the metal part to be obtained needs to have a high nitrogen content, such as high-nitrogen stainless steel, the protective gas can also include nitrogen. If the metal part to be obtained does not need to contain nitrogen, the protective gas is argon, helium, etc., and does not contain nitrogen.

[0082] Further, the protective gas is introduced from opposite sides of the container holding the molten metal. In some embodiments, the molten metal is heated by a medium frequency induction furnace, and the medium frequency induction furnace is provided with gas inlet pipes on opposite sides, and the protective gas is introduced into the molten metal through the gas inlet pipes while the molten metal is heated. Specifically, please refer to Figure 4 , the protective gas is introduced into the molten metal through the gas inlet pipes on the opposite sides. Figure 4 In

[0083] In some embodiments, the pouring speed in the step of pouring the deoxidized and deslagged molten metal into the mold shell after the wax mold module is removed is 50 cm / s to 80 cm / s. By optimizing the pouring speed, the surface defects of the metal part can be further improved, and the cleanliness can be improved. Specifically, when the pouring speed is 50 cm / s to 80 cm / s, the risk of cracking of the casting due to the large thermal stress generated by the high pouring speed can be reduced, and the risk of underfilling can be reduced. If the pouring speed is higher than 80 cm / s, surface defects such as shrinkage holes and shrinkage porosities are likely to occur, and a large thermal stress is likely to occur, increasing the risk of cracking of the casting. If the pouring speed is lower than 50 cm / s, the temperature drops too quickly during pouring, the flowability is poor, and the mold cavity may not be completely filled, resulting in underfilling defects. A long pouring time can also cause a large thermal stress in the casting.

[0084] For example, the pouring speed can be, but is not limited to, 50 cm / s, 55 cm / s, 60 cm / s, 65 cm / s, 70 cm / s, 75 cm / s, 80 cm / s, or a range formed by any two of these values.

[0085] It can be understood that in the step of pouring the deoxidized and deslagged molten metal into the mold shell after the wax mold module is removed, the molten metal fills the space formed by the wax mold module until it is completely filled, including the middle die portion.

[0086] In some embodiments, the metal part includes stainless steel. It can be understood that in other embodiments, the metal part is not limited to stainless steel, but can also be other commonly used metal parts that can be investment cast, such as carbon steel, alloy steel, heat-resistant alloy, precision alloy, permanent magnet alloy, bearing alloy, copper alloy, aluminum alloy, titanium alloy, and ductile iron.

[0087] In some embodiments, the metal part is an irregularly shaped part. An irregularly shaped part refers to a part with an irregular shape or complex structure, whose shape, size, and structure differ significantly from common standard parts. Compared to standard parts, irregularly shaped parts are more prone to surface defects due to their complex structure. Using the casting methods for metal parts in some embodiments of this application to prepare irregularly shaped parts helps reduce surface defects. It is understood that in other embodiments, the casting methods for metal parts in this application can also be used to prepare standard parts.

[0088] In some embodiments, the area of ​​the metal part is greater than or equal to 50 square decimeters. Large-area metal parts, such as those with an area greater than or equal to 50 square decimeters, are more prone to surface defects. The casting method for metal parts according to some embodiments of this application can produce large-area metal parts and reduce surface defects in large-area metal parts. It is understood that in other embodiments, the casting method for metal parts according to some embodiments of this application can also be used to produce small-area metal parts.

[0089] In some embodiments, during the cooling step, the casting is placed in water or the surface of the casting is sprayed with water to quickly remove heat by utilizing the high thermal conductivity of water.

[0090] In some of these embodiments, please refer to Figure 5 The casting method for metal parts includes the following steps:

[0091] Step S210: Prepare a wax model module using 3D printing. The wax model module includes a casting wax model and a casting wax model connected to the casting wax model. The gating gate in the casting wax model is hourglass-shaped and has a height of 20mm to 50mm.

[0092] Step S220: Apply slurry and sand to the wax model assembly to form a multi-layered mold shell on the surface of the wax model assembly. The total number of mold shell layers is 5 to 8, and the total thickness is 8 mm to 15 mm.

[0093] Step S230: Remove the wax model module.

[0094] Step S240: Firing the mold shell after removing the wax mold assembly at 1100℃~1200℃ for 40min~60min.

[0095] Step S250: Deoxidize and remove slag from the molten metal, while simultaneously introducing protective gas from opposite sides of the container holding the molten metal at a flow rate of 400L / min to 500L / min.

[0096] Step S260: Pour the deoxidized and slag-removed molten metal into the calcined mold shell at a pouring speed of 50cm / s to 80cm / s, so that the molten metal fills the mold shell, cools and solidifies, and obtains the metal part.

[0097] Figure 5 The flow chart of the casting method of the metal piece of an embodiment of the present application is shown in FIG. 1. It should be understood that although the steps in the flow chart are shown in sequence according to the arrows, the steps are not necessarily performed in the order indicated by the arrows, unless otherwise specified herein, the execution of the steps is not strictly limited in sequence, and they can be executed in other orders, and Figure 5 at least part of the steps in the flow chart can include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but can be performed at different times, and the execution sequence is not necessarily sequential, but can be performed alternately or alternately with at least part of other steps or other sub-steps or stages. Figure 5

[0098] The casting method of the metal piece has at least the following advantages:

[0099] (1) The pouring wax mold adopts a sandglass-shaped pouring gate, and the height thereof is controlled to be in the range of 20mm~50mm, effectively ensuring the stability and controllability of the molten steel flow. The enlarged caliber at the bottom of the pouring gate and the flow splitting structure promote the upward discharge of gas from the bottom of the pouring gate, significantly reducing defects such as pores, shrinkage holes and shrinkage porosity in the castings.

[0100] (2) The wax mold is made by using 3D printing technology, and is subjected to multiple times of paste sticking and sand hanging processes to form a dense mold shell with 5 layers~8 layers and a total thickness of 8mm~15mm. Such a mold shell design not only ensures the structural strength of the mold shell, but also avoids the problems of slow cooling speed and poor gas discharge caused by excessive thickness, thereby improving the quality and surface finish of the castings.

[0101] (3) By using far infrared baking technology, the mold shell is uniformly heated in all directions, reducing casting defects caused by incomplete baking. Precise control of the baking temperature and time further improves the performance and stability of the mold shell.

[0102] (4) High-temperature rapid melting metal is used, and alloy is added in time during smelting to adjust the composition. When the temperature of the molten metal reaches 1670℃~1690℃, protective gas is added to form a turbulent flow, enhancing the reaction efficiency of the deoxidizer and deslagging agent with the molten metal, and significantly improving the purity and deoxidizing and deslagging effect of the molten metal. Precise control of the flow rate of the protective gas avoids the problems of excessive disturbance on the surface of the molten metal or insufficient deoxidation reaction.

[0103] ​(5) During pouring, the pouring speed is controlled in the range of 50 cm / s to 80 cm / s, which not only ensures that the molten metal liquid can rapidly fill the cavity, but also avoids defects such as shrinkage holes and shrinkage porosities caused by too fast pouring speed or the problem of insufficient pouring caused by too slow pouring speed. In addition, accurate pouring speed control also helps to reduce the thermal stress and crack risk inside the casting.

[0104] The second aspect of the present application provides a metal piece prepared by the casting method of the metal piece of the first aspect.

[0105] In order to make the purpose and advantages of the present application clearer, the casting method of the metal piece of the present application and its effects are further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to explain the present application and should not be used to limit the present application. The following examples do not include other components except for unavoidable impurities if not specifically stated. In the examples, the drugs and instruments are selected according to the conventional selection in the art if not specifically stated. The experimental methods in the examples are implemented according to the conventional conditions, for example, the conditions described in the literature, books or the methods recommended by the manufacturers.

[0106] Example 1

[0107] The present embodiment provides a casting method of a stainless steel piece, which comprises the following steps:

[0108] (1) According to the shape of the stainless steel piece, a material with low melting point and easy melting is used for printing and forming in a 3D printer to obtain a casting mold group and a pouring mold group. The sprue of the pouring mold group is designed as a sandglass-shaped sprue, the shape of which is as shown in Figure 2 The height is controlled at 20 mm, the ratio of the minimum width to the maximum width of the sprue is 0.5, and the casting wax mold and the pouring wax mold group are combined to obtain a wax mold group.

[0109] (2) The wax mold group is immersed in a silica sol coating to wet the surface of the wax mold group. Zirconite sand is uniformly coated on the surface of the silica sol, and air drying is performed. After air drying, the above steps are repeated to perform multiple times of slurry sticking and sand hanging to obtain a multi-layer mold shell. The number of layers of the mold shell is 5, and the total thickness of the mold shell is 8 mm to 10 mm.

[0110] (3) Wax removal is performed in a wax removal machine, and the mold shell after the wax mold group is removed is baked using far infrared rays. The baking temperature is controlled at 1100°C, and the time is controlled at 40 min.

[0111] (4) The 304 stainless steel plate is melted at high temperature rapidly by using the intermediate frequency induction furnace, and materials are continuously added in the furnace to raise the temperature of the molten steel to 1670℃ for smelting. When the temperature reaches 1670℃, the composition of the molten steel is tested, and the corresponding alloy is added according to the composition of the molten steel. When the temperature of the molten steel is 1670℃, deoxidation and deslagging are carried out. The initial deoxidation uses electrolytic manganese alloy, and the final deoxidation uses composite iron alloy. Two gas inlet pipes are added in the intermediate frequency induction furnace, and argon gas enters the molten steel through the gas inlet pipes. The argon gas flow is controlled at 400L / min to form a turbulent flow in the molten steel, so that the deoxidizer can quickly react with the molten steel and the oxides can quickly float on the surface of the molten steel, and the deslagging agent is used for deslagging.

[0112] (5) Pour the molten stainless steel into the dewaxed mold shell, and the liquid stainless steel fills the space formed by the wax mold module until it is completely filled. The pouring speed is controlled at 50cm / s.

[0113] (6) Place the casting in water or spray water on the surface of the casting, and use the high thermal conductivity of water to quickly remove heat to obtain a stainless steel part.

[0114] Examples 2-6

[0115] Examples 2-6 respectively provide a casting method of a stainless steel part, and the preparation steps are similar to those of Example 1, and the difference lies in different process parameters. The process parameters of Examples 2-6 are shown in Table 1. The rest is the same as Example 1 and will not be repeated.

[0116] Comparative Example 1

[0117] Comparative Example 1 provides a casting method of a stainless steel part, which refers to the method in CN 110090921A, including the following steps:

[0118] (1) According to the shape of the stainless steel part, a material with low melting point and easy melting is used to print on a 3D printer to obtain a casting mold module and a pouring mold module, wherein the pouring gate of the pouring mold module is a straight cylinder with a height of 30mm, and the casting wax mold and the pouring wax mold module are combined to obtain a wax mold module.

[0119] (2) Dip the wax mold module into the silica sol coating to wet the surface of the wax mold module, and evenly coat zircon sand on the surface of the silica sol and dry it. After drying, repeat the above steps to obtain a multi-layer mold shell by repeatedly sticking and sanding. The number of layers of the mold shell is 6, and the total thickness of the mold shell is 12mm.

[0120] (3) De-waxing to obtain a mold shell.

[0121] (4) Baking the mold shell at a temperature of 1150℃ for 40 minutes.

[0122] (4) pouring, the pouring temperature is 1640℃, the pouring speed is less than or equal to 3 seconds, and then natural cooling, after demolding, a large-area thin-walled part is obtained.

[0123] Comparative Examples 2-3

[0124] Comparative Examples 2-3 respectively provide a casting method of a stainless steel part, the preparation steps are similar to those of Example 1, the difference lies in that the sprue height in step (1) is different. The sprue height of Comparative Examples 2-3 is shown in Table 2. The remaining steps and parameters are the same as those of Example 1, and will not be repeated here.

[0125] Comparative Example 4

[0126] Comparative Example 4 provides a casting method of a stainless steel part, the preparation steps are similar to those of Example 1, the difference lies in that the shape of the sprue in step (1) is different, in Comparative Example 4, the shape of the sprue is a straight cylinder, that is, the width of the sprue at different positions is the same, and the maximum width of the sprue is the same as that in Example 1. The other steps and parameters are the same as those of Example 1, and will not be repeated here.

[0127] Comparative Examples 5-6

[0128] Comparative Examples 5-6 respectively provide a casting method of a stainless steel part, the preparation steps are similar to those of Example 1, the difference lies in that the argon flow rate in step (4) is different, the argon flow rate of Comparative Examples 5-6 is shown in Table 2. The remaining steps and parameters are the same as those of Example 1, and will not be repeated here.

[0129] Comparative Example 7

[0130] Comparative Example 7 provides a casting method of a stainless steel part, the preparation steps are similar to those of Example 1, the difference lies in that the way of introducing argon in step (4) is different, in Comparative Example 7, the bottom of the intermediate frequency induction furnace is provided with an air inlet pipe, and the argon enters the molten steel through the air inlet pipe at the bottom. The remaining steps are the same as those of Example 1, and will not be repeated here.

[0131] Table 1 Process parameters of the casting method of the stainless steel part of each example

[0132]

[0133] Table 2 Process parameters of the casting method of the stainless steel part of each comparative example

[0134]

[0135] The surface appearance of the shaped parts for casting stainless steel of Examples 1-6 and Comparative Examples 1-7 is tested, and the results are shown in Table 3.

[0136] Table 3 Casting surface appearance results of shaped parts

[0137]

[0138] The super-depth microscope of the stainless steel part prepared in Comparative Example 1 is shown in Figure 6 , the actual image is shown in Figure 7 , and the polished appearance is shown in Figure 8 . As can be seen from Figure 6 , the stainless steel part prepared in Comparative Example 1 has many surface inclusions. As can be seen from Figure 7 , the stainless steel part of Comparative Example 1 has insufficient pouring and cold shut defects. As can be seen from Figure 8 , the stainless steel part of Comparative Example 1 has a cold shut defect.

[0139] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0140] The above-described embodiments only express several implementation manners of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but should not be understood as a limitation on the scope of patent protection. It should be pointed out that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. It should be understood that, on the basis of the technical solutions provided by the present application, the technical solutions obtained by logical analysis, reasoning or limited experiments by those skilled in the art are all within the scope of protection of the appended claims of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the contents of the appended claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. A casting method of a metal piece, characterized by, The method comprises the following steps: obtaining a wax mold module, wherein the wax mold module comprises a casting wax mold and a pouring wax mold connected with the casting wax mold; wherein the pouring gate of the pouring wax mold is in the shape of a sandglass, and the height of the pouring gate is 20mm-50mm; performing slurry sticking and sand hanging on the wax mold module to form a mold shell on the surface of the wax mold module; removing the wax mold module; adding a deoxidizer and a slag remover to the molten metal liquid to perform deoxidation and slag removal on the molten metal liquid, and simultaneously introducing a protective gas from the side of a container carrying the molten metal liquid at a flow rate of 400L / min-500L / min; pouring the deoxidized and slag-removed molten metal liquid into the mold shell after removing the wax mold module to fill the molten metal liquid in the mold shell, and cooling to form a metal piece.

2. The casting method of metal pieces according to claim 1, characterized in that, The maximum width of the pouring gate is R1, and the minimum width of the pouring gate is R2, and R2 / R1 is 0.4-0.6; and / or, The inner wall of the pouring gate is in the shape of a circular arc.

3. The casting method of metal pieces according to claim 1, characterized in that, The protective gas is introduced from opposite sides of the container carrying the molten metal liquid.

4. The casting method of metal pieces according to claim 3, characterized in that, The molten metal liquid is heated by a medium-frequency induction furnace, and the opposite sides of the medium-frequency induction furnace are provided with air inlet pipes, so that the protective gas is introduced into the molten metal liquid through the air inlet pipes while the molten metal liquid is heated.

5. The casting method of metal pieces according to claim 1, 3 or 4, characterized in that, The protective gas comprises argon.

6. The casting method of metal pieces according to claim 1, characterized in that, The total thickness of the mold shell is 8mm-15mm, and the total number of layers is 5-8.

7. The casting method of metal pieces according to claim 1 or 6, characterized in that, After the step of removing the wax mold module and before the step of pouring the molten metal liquid, the method further comprises: baking the mold shell at 1100℃-1200℃ for 40min-60min.

8. The method of casting a metal piece according to claim 7, wherein, The mold shell is baked by far infrared rays.

9. The casting method of a metal piece according to any one of claims 1 to 4 and 6, characterized in that, In the step of pouring the deoxidized and slag-removed molten metal liquid into the mold shell after removing the wax mold module, the pouring speed is 50cm / s-80cm / s.

10. The casting method of a metal piece according to any one of claims 1 to 4 and 6, characterized in that, The wax mold module is prepared by 3D printing.

11. The casting method of a metal piece according to any one of claims 1 to 4 and 6, characterized in that, The metal piece comprises stainless steel; and / or, The metal piece is a special-shaped piece; and / or, The area of the metal piece is greater than or equal to 50 square decimeters.

12. A metal piece, characterized by The metal piece is prepared by the casting method of any one of claims 1-11.

Images