Method for preparing high-precision aluminum alloy part based on injection molding

Abstract

The invention discloses a method for preparing a high-precision aluminum alloy part based on injection molding, which is characterized in that a modifier is added into a polyformaldehyde (POM)-based binder, so that the compatibility of the polyformaldehyde (POM)-based binder and aluminum alloy powder can be effectively improved, and after the polyformaldehyde (POM)-based binder is mixed with the aluminum alloy powder, the powder distribution is more uniform, and the strength of the aluminum alloy part is improved. The compactness and the structural strength of the injection molding aluminum alloy part are further improved; by adding ethylene bis stearamide, polyesteramide and stearic acid, the interface relationship between the powder and the binder can be improved, intermolecular or intramolecular interaction between the powder and the binder is promoted, the compatibility between the powder and the binder is improved, gaps are fully filled with the binder, the powder is wrapped with the binder, the friction force between the powder is remarkably reduced, and the service life of the binder is prolonged. Further, the viscosity of the whole feed is reduced; the raw materials with the double-peak granularity have higher flowability, the powder and the binder are uniformly distributed, and the material is more suitable for mold filling.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing aluminum alloy parts. More specifically, the present invention relates to a method for preparing high-precision aluminum alloy parts based on injection molding. Background Art

[0002] Metal injection molding (MIM) is a near-net-shape forming technology derived from the combination of plastic injection molding and powder metallurgy sintering processes, and is used to manufacture complex-shaped metal parts.

[0003] The metal injection molding technology does not require machining and can be rapidly formed at one time, simplifying the secondary processing operations and reducing processing waste; the metal injection molding technology can mass-produce small and medium-sized complex-shaped parts with high workpiece precision and excellent mechanical properties; in the metal injection molding process, metal powder needs to be fully mixed with a binder to obtain a feedstock, and then injection, debinding, and sintering are carried out. The aluminum alloy powder injection molding and sintering process is to mix aluminum alloy powder with a binder and then carry out injection molding, and after forming a preliminary-shaped blank, drying, sintering and other processes are carried out to finally obtain a solid part. The design of the binder in the metal injection molding process is very important. The binder not only makes the prepared feedstock have fluidity and plasticity, so that injection molding can be carried out smoothly, but also the addition of the binder improves the strength of the green body, and can maintain the shape of the green body until the pre-sintering stage after the green body is formed.

[0004] Polyoxymethylene (POM)-based binders have advantages such as high demolding efficiency, good shape adaptability, low residues, and satisfactory dimensional accuracy; however, the compatibility between POM and aluminum alloy powder is poor, resulting in uneven powder distribution in the binder. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a method for preparing high-precision aluminum alloy parts based on injection molding.

[0006] A method for preparing high-precision aluminum alloy parts based on injection molding specifically includes the following steps:

[0007] Step 1: Add aluminum alloy powder into the mixing cavity of a mixing device, first carry out stirring and preheating treatment for 1 to 3 hours, then stir and heat up, add a binder and continue stirring for 50 to 70 minutes, and cool to room temperature to obtain a feedstock;

[0008] Step 2: Feed the feedstock into an injection molding machine for injection molding to obtain a blank;

[0009] Step 3: Carry out debinding treatment on the blank to obtain a debound blank;

[0010] Step 4: Sinter the degreased blank to obtain a high-precision aluminum alloy part.

[0011] Further, in Step 1, the stirring speed during the stirring preheating treatment is 20 - 30 r / min, and the preheating temperature is 105 - 115 °C; the temperature for stirring heating and subsequent stirring is 185 - 195 °C, and the stirring speed for stirring heating and subsequent stirring is 40 - 50 r / min.

[0012] Further, in Step 2, the injection pressure of the injection molding machine is 118 - 122 MPa, the holding pressure is 1 - 3 s, the injection temperature is 135 - 145 °C, the injection time is 3 s, and the cooling time is 8 - 12 s.

[0013] Further, in Step 3, first perform catalytic degreasing treatment on the blank, and then perform thermal degreasing treatment.

[0014] Further, during the catalytic degreasing treatment, oxalic acid is used as the catalyst, and the catalytic degreasing temperature is 105 - 115 °C; the heating rate for thermal degreasing treatment is 2 °C / min, and it is heated to 500 °C and held for 50 - 70 minutes.

[0015] Further, the degreased blank is sintered in a tubular furnace:

[0016] S1: Heat from room temperature to 350 °C at a rate of 2 °C / min and hold for 1 hour;

[0017] S2: Increase the temperature to 450 °C at a rate of 1 °C / min and hold for 1 hour;

[0018] S3: Increase the temperature to 500 °C at a rate of 1 °C / min and hold for 1 hour;

[0019] S4: Heat up to 580 °C, hold for 1 hour, and then cool the chamber to room temperature;

[0020] S5: Perform homogenization heat treatment on the product in a muffle furnace with a heating rate of 5 °C / min: hold at 470 °C for 12 hours, and then hold at 485 °C for 12 hours to obtain a high-precision aluminum alloy part;

[0021] The whole process is carried out under the protection of nitrogen with a flow rate of 2.8 - 3.2 L / min.

[0022] Further, in Step 1, the weight ratio of the aluminum alloy powder to the binder is (1.9 - 2.1)∶1.

[0023] Further, the binder includes, by weight percentage: 13.1% - 13.9% of the skeleton, 0.9% - 1.1% of ethylene bisstearamide, 0.9% - 1.1% of polyamide ester, 0.9% - 1.1% of stearic acid, and the rest is polyoxymethylene.

[0024] Furthermore, the skeleton is one or a compound of high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), or polypropylene (PP).

[0025] Furthermore, the aluminum alloy powder includes nano-level aluminum alloy powder and micron-level aluminum alloy powder; the shapes of both the nano-level aluminum alloy powder and the micron-level aluminum alloy powder are spherical particles, and the volume ratio of the nano-level aluminum alloy powder to the micron-level aluminum alloy powder is 1∶(2.8 - 3.2).

[0026] The technical effects and advantages of the present invention:

[0027] 1. For the high-precision aluminum alloy parts prepared using the raw material formula of the present invention, by adding a modifier to the polyoxymethylene (POM) - based binder, the compatibility between the polyoxymethylene (POM) - based binder and the aluminum alloy powder can be effectively improved. After the polyoxymethylene (POM) - based binder and the aluminum alloy powder are mixed, the powder distribution becomes more uniform, thereby improving the density and structural strength of the injection - molded aluminum alloy parts; the addition of ethylene bisstearamide, polyamide ester, and stearic acid can improve the interfacial relationship between the powder and the binder, enabling the binder to fully fill the voids and wrap the powder, significantly reducing the friction between the powders, and thus reducing the overall viscosity of the feedstock; the additive can promote the intermolecular or intramolecular interaction between the powder and the binder, improving their compatibility; the spherical - particle aluminum alloy powder reduces the internal particle friction, allowing better flow, making the microstructure of the high - precision aluminum alloy parts more uniform, and the raw materials with bimodal particle size have higher fluidity, with the powder and the binder being evenly distributed, being more suitable for mold filling;

[0028] 2. In the present invention, preheating the aluminum alloy powder inside the mixing chamber can effectively ensure the surface drying performance of the aluminum alloy powder. Continuing to heat up and waiting to be blended with the binder, blending the binder of the aluminum alloy powder under the heating and holding state ensures that the binder is in a liquid state and is rapidly and evenly blended with the solid - state aluminum alloy powder, ensuring the uniformity of the distribution of the aluminum alloy powder inside the feedstock; injecting and molding the feedstock in an injection molding machine to produce a blank; first performing catalytic debinding and then thermal debinding on the blank can effectively avoid deformation and collapse of the blank while debinding the blank; sintering the debound blank, since the aluminum alloy powder has high reactivity and forms a dense oxide film on its surface, in order to promote densification and prevent secondary oxidation, a high - flow nitrogen atmosphere is used during the sintering process. During the sintering process, a two - stage homogenization annealing treatment is adopted, which will not cause over - burning of the alloy and is beneficial to improving the homogenization effect; it can effectively improve the non - uniformity of the chemical composition and structure of the aluminum alloy parts, reduce dendritic segregation, and improve the subsequent processing performance of the alloy. Specific embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] The present invention provides a method for preparing high-precision aluminum alloy parts based on injection molding, specifically including the following steps:

[0032] Step 1: Add aluminum alloy powder into the mixing chamber of the mixing equipment, first perform stirring and preheating treatment for 2 hours, then stir and heat up, add the binder and continue stirring for 60 minutes, and cool to room temperature to obtain the feedstock; the stirring speed during the stirring and preheating treatment is 25 r / min, and the preheating temperature is 110 °C; the temperature of stirring and heating and subsequent stirring is 190 °C, and the stirring speed of stirring and heating and subsequent stirring is 45 r / min; the weight ratio of the aluminum alloy powder to the binder is 1.9:1; the binder includes, by weight percentage: 13.1% polypropylene PP, 0.9% ethylene bisstearamide, 0.9% polyamide ester, 0.9% stearic acid, 84.2% polyoxymethylene. The above raw materials are blended evenly to obtain the binder; the aluminum alloy powder includes nano-scale aluminum alloy powder with a spherical particle structure and micron-scale aluminum alloy powder; the volume ratio of the nano-scale aluminum alloy powder to the micron-scale aluminum alloy powder is 1:2.8;

[0033] Step 2: Feed the feedstock into an injection molding machine for injection molding to obtain a blank; the injection pressure of the injection molding machine is 120 MPa, the holding pressure is 2 s, the injection temperature is 140 °C, the injection time is 3 s, and the cooling time is 10 s;

[0034] Step 3: Perform degreasing treatment on the blank to obtain a degreased blank; first perform catalytic degreasing treatment on the blank, and then perform thermal degreasing treatment; during the catalytic degreasing treatment, oxalic acid is used as the catalyst, and the catalytic degreasing temperature is 110 °C; the heating rate of the thermal degreasing treatment is 2 °C / min, and it is heated to 500 °C and held for 60 minutes;

[0035] Step 4: Perform sintering treatment on the degreased blank to obtain high-precision aluminum alloy parts; the degreased blank is sintered in a tube furnace:

[0036] S1: Heat from room temperature to 350 °C at a rate of 2 °C / min and hold for 1 hour;

[0037] S2: Heat to 450 °C at a rate of 1 °C / min and hold for 1 hour;

[0038] S3: Heat at a rate of 1 °C / min to 500 °C and hold for 1 hour;

[0039] S4: Heat up to 580 °C, hold for 1 hour, and then cool the chamber to room temperature;

[0040] S5: Conduct homogenization heat treatment of the product in a muffle furnace at a heating rate of 5 °C / min: hold at 470 °C for 12 hours and then hold at 485 °C for 12 hours to obtain high-precision aluminum alloy parts;

[0041] The whole process is carried out under the protection of nitrogen with a flow rate of 3.0 L / min;

[0042] Oxalic acid is purchased from Jinan Guocheng Chemical Co., Ltd., product number: 0254152; polypropylene PP is purchased from Shanghai Yuanye Bio-Technology Co., Ltd., product number: S51655; ethylene bisstearamide is purchased from Shanghai Yuanye Bio-Technology Co., Ltd., product number: S60452; polyamide ester is purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model: HyPerHPN202; stearic acid is purchased from Nantong Runfeng Petrochemical Co., Ltd., purity: 99%, brand: Runfeng; polyoxymethylene is purchased from Shanghai Huihang New Materials Co., Ltd., brand: DuPont USA, grade: POM500P; nano-scale aluminum alloy powder and micro-scale aluminum alloy powder are 7075 aluminum alloy powder purchased from Shanghai Xiangtian Nano Materials Co., Ltd.

[0043] Example 2:

[0044] Differing from Example 1, the weight ratio of the aluminum alloy powder to the binder is 2.1:1; the binder includes, by weight percentage: 13.9% of polypropylene PP, 1.1% of ethylene bisstearamide, 1.1% of polyamide ester, 1.1% of stearic acid, and 82.8% of polyoxymethylene; the aluminum alloy powder includes nano-scale aluminum alloy powder and micro-scale aluminum alloy powder with a spherical particle structure; the volume ratio of the nano-scale aluminum alloy powder to the micro-scale aluminum alloy powder is 1:3.2.

[0045] Example 3:

[0046] Differing from both Example 1 and Example 2, the weight ratio of the aluminum alloy powder to the binder is 2:1; the binder includes, by weight percentage: 13.5% of polypropylene PP, 1.0% of ethylene bisstearamide, 1.0% of polyamide ester, 1.0% of stearic acid, and 83.5% of polyoxymethylene; the aluminum alloy powder includes nano-scale aluminum alloy powder and micro-scale aluminum alloy powder with a spherical particle structure; the volume ratio of the nano-scale aluminum alloy powder to the micro-scale aluminum alloy powder is 1:3.

[0047] Comparative Example 1:

[0048] Different from Example 3: The binder includes, by weight percentage: 13.5% polypropylene PP and 86.5% polyoxymethylene.

[0049] Comparative Example 2:

[0050] Different from Example 3: The binder includes, by weight percentage: 13.5% polypropylene PP, 1.0% polyamide ester, 1.0% stearic acid, and 84.5% polyoxymethylene.

[0051] Comparative Example 3:

[0052] Different from Example 3: The binder includes, by weight percentage: 13.5% polypropylene PP, 1.0% ethylene bisstearamide, 1.0% stearic acid, and 84.5% polyoxymethylene.

[0053] Comparative Example 4:

[0054] Different from Example 3: The aluminum alloy powder includes nano-scale aluminum alloy powder with a spherical particle structure and micron-scale aluminum alloy powder; the volume ratio of the nano-scale aluminum alloy powder to the micron-scale aluminum alloy powder is 3:1.

[0055] Comparative Example 5:

[0056] Different from Example 3: The aluminum alloy powder is micron-scale aluminum alloy powder with a spherical particle structure.

[0057] Comparative Example 6:

[0058] Different from Example 3: A method for preparing high-precision aluminum alloy parts based on injection molding specifically includes the following steps:

[0059] Step 1: Add the aluminum alloy powder into the mixing chamber of the mixing equipment, first perform stirring and preheating treatment for 2 hours, then stir and heat up, add the binder and continue stirring for 60 minutes, and cool to room temperature to obtain the feed; the stirring speed during the stirring and preheating treatment is 25 r / min, and the preheating temperature is 110°C; the temperature of stirring and heating and subsequent stirring is 190°C, and the stirring speed of stirring and heating and subsequent stirring is 45 r / min; the weight ratio of the aluminum alloy powder to the binder is 2:1; the binder includes, by weight percentage: 13.5% polypropylene PP, 1.0% ethylene bisstearamide, 1.0% polyamide ester, 1.0% stearic acid, and 83.5% polyoxymethylene; the aluminum alloy powder includes nano-scale aluminum alloy powder with a spherical particle structure and micron-scale aluminum alloy powder; the volume ratio of the nano-scale aluminum alloy powder to the micron-scale aluminum alloy powder is 1:3;

[0060] Step 2: Feed the feedstock into an injection molding machine for injection molding to obtain a blank; the injection pressure of the injection molding machine is 120 MPa, the holding pressure is 2 s, the injection temperature is 140 °C, the injection time is 3 s, and the cooling time is 10 s;

[0061] Step 3: Debind the blank to obtain a debound blank; first perform catalytic debinding on the blank, and then perform thermal debinding; when performing catalytic debinding, oxalic acid is used as the catalyst, and the catalytic debinding temperature is 110 °C; the heating rate of thermal debinding is 2 °C / min, and it is heated to 500 °C and held for 60 minutes;

[0062] Step 4: Sinter the debound blank to obtain a high-precision aluminum alloy part; the debound blank is sintered in a tube furnace:

[0063] S1: Heat from room temperature to 350 °C at a rate of 2 °C / min for 1 hour;

[0064] S2: Increase the temperature to 450 °C at a rate of 1 °C / min and hold for 1 hour;

[0065] S3: Increase the temperature to 500 °C at a rate of 1 °C / min and hold for 1 hour;

[0066] S4: Heat up to 580 °C and hold for 1 hour, then cool the chamber to room temperature to obtain a high-precision aluminum alloy part;

[0067] The whole process is carried out under the protection of nitrogen with a flow rate of 3.0 L / min.

[0068] The high-precision aluminum alloy parts in the comparative examples and examples of the present invention are detected:

[0069] The sintered density of the high-precision aluminum alloy parts is measured by the Archimedes drainage method; the tensile properties of the high-precision aluminum alloy parts are evaluated using a universal testing machine (Instron 3369, USA);

[0070] The results are shown in Table 1:

[0071] Table 1:

[0072]

[0073]

[0074] As can be seen from the above table: In the method for preparing high-precision aluminum alloy parts based on injection molding in the present invention, by adding a modifier to the polyoxymethylene (POM) - based binder, the compatibility between the polyoxymethylene (POM) - based binder and aluminum alloy powder can be effectively improved. After the polyoxymethylene (POM) - based binder and aluminum alloy powder are mixed, the powder distribution is more uniform, thereby improving the density and structural strength of the injection - molded aluminum alloy parts.

[0075] In Step 1, aluminum alloy powder is added into the internal mixing chamber for preheating, which can effectively ensure the surface drying performance of the aluminum alloy powder. Then, heating is continued to raise the temperature, waiting to be blended with the binder. Under the condition of heating and holding, the binder of the aluminum alloy powder is blended to ensure that the binder in a liquid state is rapidly and evenly blended with the solid aluminum alloy powder, ensuring the uniformity of the distribution of the aluminum alloy powder inside the feedstock. In Step 2, the feedstock is injection-molded in an injection molding machine to produce a blank. Through heating and injection of the feedstock and cooling and molding in the mold of the injection molding machine, the rapid injection molding of the blank can be effectively ensured. In Step 3, the blank is degreased, and the blank is first subjected to catalytic degreasing and then thermal degreasing, which can effectively avoid deformation and collapse of the blank while degreasing the blank. In Step 4, the degreased blank is sintered. Since the aluminum alloy powder has high reactivity and a dense oxide film is formed on its surface, in order to promote densification and prevent secondary oxidation, a high-flow nitrogen atmosphere is used during the sintering process. During the sintering process, a two-stage uniform annealing treatment of (70 °C / 12 h)+(485 °C / 12 h) is adopted, which will not cause overburning of the alloy. The two-stage uniform annealing process is beneficial to improving the homogenization effect; it can effectively improve the non-uniformity of the chemical composition and structure of the aluminum alloy parts, reduce dendritic segregation, and improve the subsequent processing performance of the alloy;

[0076] In the present invention, the natural oxide layer on the surface of the aluminum alloy can further react with water or hydroxide to generate hydroxyl groups (—OH). Ethylene bisstearamide changes the intermolecular forces on the surface of the aluminum alloy powder, indicating the existence of intermolecular or intramolecular interactions, which promotes the bonding between the powder and the binder. The molecular structure of ethylene bisstearamide contains two amide groups, and the nitrogen and oxygen atoms in the amide groups have lone pairs of electrons that can participate in hydrogen bonding, and ethylene bisstearamide will adhere to the surface of the aluminum alloy powder particles. The long alkane chain structure of ethylene bisstearamide is similar to that of polyoxymethylene. Adding ethylene bisstearamide during the mixing process can improve the compatibility between the aluminum alloy powder and polyoxymethylene. The binder exhibits strong pseudoplasticity. At high shear rates, the viscosity of the binder decreases most significantly, making the binder have good fluidity. Good fluidity enhances the rheological stability of the raw materials, thereby endowing the injection parts with good structural strength and retention force. Using polyamide ester as a modifier for the polyoxymethylene-based binder, the addition of polyamide ester as a hyper-esterified polymer can effectively improve the fluidity and uniformity of the polyoxymethylene-based binder, and at the same time can improve the flexural strength and impact strength of the green body and the tensile strength of the high-precision aluminum alloy parts. Stearic acid can chemically adsorb on the surface of the aluminum alloy powder, and the remaining part of the molecular chain extends into the binder, which can effectively enhance the interaction between the aluminum alloy powder and the binder, reduce powder agglomeration, thereby reducing the viscosity and improving the feeding uniformity. The addition of ethylene bisstearamide, polyamide ester, and stearic acid can improve the interfacial relationship between the powder and the binder, enabling the binder to fully fill the voids and wrap the powder, significantly reducing the friction between the powders, and further reducing the viscosity of the overall feed. The powder particles are preferably spherical. The spherical aluminum alloy powder reduces internal particle friction, allows better flow, and makes the microstructure of the high-precision aluminum alloy parts more uniform. Mixing raw materials of micron-sized and nano-sized particles with a bimodal size distribution of particles forms a bimodal grain structure, and has higher fluidity. The agglomerated nano-powders are crushed and rearranged in the gaps of the micro-powders. The powder and the binder are evenly distributed and have good flow performance. The addition of nano-powders can increase the grain boundaries and micropores, providing a good diffusion path for rapid densification, and can also effectively inhibit grain boundary migration and grain growth. The raw materials with bimodal particle sizes are more suitable for mold filling;

[0077] The green body exhibits high dimensional accuracy and a smooth and defect-free surface. The binder is evenly distributed in the network structure surrounding the powder particles. During the catalytic debinding process, most of the POM in the green body rapidly decomposes into small formaldehyde molecules and is then removed. The catalytic debinding temperature is maintained below the melting point of POM, effectively preventing the formation of a liquid phase. This enables the green body to maintain its shape while forming porous spaces, which serve as channels for thermal debinding. After debinding, the resulting porous structure consists of an interconnected pore network, which is beneficial for the subsequent sintering process;

[0078] The C and O elements in the high-precision aluminum alloy parts are evenly distributed, effectively controlling carbon oxides during the sintering process and promoting the densification of the alloy. In addition, the Cu, Mg, and Si elements tend to aggregate, which helps to form reinforcement phases, thereby improving the overall performance of the material. The white Al2Cu phase and gray Mg2Si phase present in the high-precision aluminum alloy parts further enhance the densification and strength, indicating good sintering performance and interfacial bonding ability. During the sintering process, the lower carbon and oxygen contents reduce the formation of carbides and oxides, thus optimizing the microstructure and mechanical properties of the sintered aluminum alloy. Additives can promote the intermolecular or intramolecular interactions between the powder and the binder, improving their compatibility. When the C and O contents in the sintered and degreased blank are the lowest, it will accelerate the formation of intermediate phases such as Al2Cu and Mg2Si, improving the densification and structural strength of the high-precision aluminum alloy parts.

[0079] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing high-precision aluminum alloy parts based on injection molding, characterized in that: Specifically, it includes the following steps: Step 1: Add aluminum alloy powder into the mixing cavity of the mixing equipment, first conduct stirring and preheating treatment for 1 - 3 hours, then stir and heat up, add the binder and continue stirring for 50 - 70 minutes, and cool to room temperature to obtain the feedstock; Step 2: Feed the feedstock into an injection molding machine for injection molding treatment to obtain a blank; Step 3: Debind the blank to obtain a debound blank; Step 4: Sinter the debound blank to obtain a high-precision aluminum alloy part.

2. The method for preparing high-precision aluminum alloy parts based on injection molding according to claim 1, wherein: In Step 1, the stirring speed during the stirring and preheating treatment is 20 - 30 r / min, and the preheating temperature is 105 - 115 °C; the temperature for stirring and heating and subsequent stirring is 185 - 195 °C, and the stirring speed for stirring and heating and subsequent stirring is 40 - 50 r / min.

3. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 1, characterized in that: In Step 2, the injection pressure of the injection molding machine is 118 - 122 MPa, the holding pressure is 1 - 3 s, the injection temperature is 135 - 145 °C, the injection time is 3 s, and the cooling time is 8 - 12 s.

4. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 1, characterized in that: In Step 3, first conduct catalytic debinding treatment on the blank, and then conduct thermal debinding treatment.

5. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 4, characterized in that: During the catalytic debinding treatment, oxalic acid is used as the catalyst, and the catalytic debinding temperature is 105 - 115 °C; the heating rate for thermal debinding treatment is 2 °C / min, and it is heated to 500 °C and held for 50 - 70 minutes.

6. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 1, characterized in that: The debound blank is sintered in a tube furnace: S1: Heat from room temperature to 350 °C at a rate of 2 °C / min and hold for 1 hour; S2: Heat to 450 °C at a rate of 1 °C / min and hold for 1 hour; S3: Heat to 500 °C at a rate of 1 °C / min and hold for 1 hour; S4: Heat to 580 °C and hold for 1 hour, then cool the chamber to room temperature; S5: Conduct homogenization heat treatment on the product in a muffle furnace, with a heating rate of 5 °C / min: hold at 470 °C for 12 hours, and then hold at 485 °C for 12 hours to obtain a high-precision aluminum alloy part; The whole process is carried out under the protection of nitrogen with a flow rate of 2.8 - 3.2 L / min.

7. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 1, characterized in that: In Step 1, the weight ratio of the aluminum alloy powder to the binder is (1.9 - 2.1) :

1.

8. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 7, characterized in that: The binder includes, by weight percentage: 13.1% - 13.9% of the skeleton, 0.9% - 1.1% of ethylene bisstearamide, 0.9% - 1.1% of polyamide ester, 0.9% - 1.1% of stearic acid, and the rest is polyoxymethylene.

9. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 8, characterized in that: The skeleton is one or a combination of high-density polyethylene HDPE, ethylene - vinyl acetate copolymer EVA, or polypropylene PP.

10. A method for preparing high-precision aluminum alloy parts based on injection molding according to claim 7, characterized in that: The aluminum alloy powder includes nano-scale aluminum alloy powder and micro-scale aluminum alloy powder; the shapes of both the nano-scale aluminum alloy powder and the micro-scale aluminum alloy powder are spherical particles, and the volume ratio of the nano-scale aluminum alloy powder to the micro-scale aluminum alloy powder is 1 : (2.8 - 3.2).

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