A preparation process for large high-performance paste-solidified aluminum alloy shell cone castings

Abstract

This invention discloses a process for preparing a large, high-performance, paste-like solidified aluminum alloy shell cone casting, belonging to the field of aluminum alloy casting technology. This process utilizes a sand mold differential pressure casting method, employs a bottom-pouring slot gating system, and prepares a mold according to a gating system design verified using PROCAST simulation software. The process then proceeds through mold preparation, alloy smelting, differential pressure casting, sand cleaning, riser cutting, casting processing inspection and finishing, and T5 heat treatment to produce a high-performance, paste-like solidified aluminum alloy shell cone casting.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy casting, and in particular relates to a preparation process of a large-scale high-performance pasty solidified aluminum alloy shell cone casting. Background Art

[0002] High-performance aluminum castings play an important role in the lightweighting of aviation and aerospace equipment. Under effective load, the lighter the component, the greater the weight margin, which is more conducive to improving the maneuverability, long-range and efficiency of the equipment.

[0003] Currently, due to the constraints of difficult-to-form special materials and large, complex structures with variable wall thickness, traditional processes have common problems in forming high-end lightweight large castings that need to be solved urgently:

[0004] First, internal defects exceed standards. Pasty solidification alloys have a wide crystallization temperature range (the solid-liquid interval is close to 100°C), poor fluidity, and extremely difficult to achieve sequential solidification. Quality problems such as shrinkage cavities and looseness are prone to occur inside castings. Hydrogen evolution is severe during mold filling under atmospheric or negative pressure, leading to excessive internal pinholes. High-density elements such as Cu easily precipitate during smelting and mold filling, causing gravity segregation. Furthermore, areas with variable wall thickness are prone to thermal cracking due to localized thermal stress concentration. Dendrites near thermal cracks have high solute concentrations, and melt shrinkage leads to point, linear, or cloud-like segregation.

[0005] The second is coarse structure and poor performance. The effective shrinkage feeding distance of the alloy riser with paste solidification characteristics is short, the shrinkage feeding effect in the middle and lower parts of the casting is poor, the shrinkage feeding channel is difficult to establish, and the solidification structure is not dense; the cavity structure is complex, the filling is not stable and it is easy to oxidize and entrap gas; during solidification, the α solid solution grows excessively, and the θ (Al2Cu) and T (Al 12 The strengthening phases such as Mn2Cu) are segregated at the grain boundaries, resulting in coarse grains and poor performance of the casting. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation process for large-scale high-performance mushy solidification aluminum alloy shell cone castings, which is used to solve the technical problems of excessive internal defects and poor organizational properties in the casting of large-scale mushy solidification aluminum alloys.

[0007] The present invention is achieved through the following technical solutions:

[0008] A process for preparing a large, high-performance, pasty-solidified aluminum alloy shell cone casting comprises the following steps:

[0009] S1. After applying a release agent on the working surface of the sand casting mold of the aluminum alloy shell cone casting, perform molding and cleaning, and then continue to apply paint on the working surface of the sand mold and dry it;

[0010] S2, refining the sand casting mold of the aluminum alloy shell cone casting after the above-mentioned coating is dried;

[0011] S3, cooling the sand casting mold of the aluminum alloy shell cone casting after the above-mentioned refining treatment, and then performing casting treatment, heat treatment, and aging treatment to obtain a finished casting.

[0012] Preferably, in step S1, the core box design shrinkage rate of the sand casting mold of the aluminum alloy shell cone casting is 0.75%-0.85%, and the exterior design shrinkage rate is 0.9%-1.05%;

[0013] Preferably, the core box design shrinkage rate is 0.8%, and the exterior design shrinkage rate is 1%.

[0014] The above can design the casting gating system of the casting based on the structural characteristics of the casting using 3D drawing software, combine with ProCast software for numerical simulation, and optimize the gating system; manufacture the sand casting mold of the aluminum alloy shell cone casting according to the gating system design drawings.

[0015] Preferably, in step S1, the release agent is applied with a thickness of 0.5 mm to 0.7 mm.

[0016] The above-mentioned release agent comes from: Shandong Zhucheng Shengping Casting Materials Co., Ltd., sand core (mold) release agent.

[0017] Preferably, in step S1, the shaping process includes using a shaping device to perform sand mixing, flow coating, film forming, and box assembly;

[0018] The modeling agent is composed of a curing agent, furan resin and dry sand in a mass fraction ratio of (30-40):1:(1-1.25).

[0019] Preferably, in step S1, the cleaning process includes sand removal, drying and mold closing;

[0020] The drying temperature is 150-160° C., and the drying time is 1.5-2 hours.

[0021] The above-mentioned molding equipment can be molded using automated molding equipment with a sand mixing efficiency of 20t / h. The automated molding equipment used has functions such as precise flow sand mixing, frequency adaptive vibration molding, and mold flow coating box, which can effectively ensure the sand mold dimensional accuracy and surface roughness.

[0022] Preferably, in step S1, the coating continuously applied on the working surface is a graphite-based coating, and the coating thickness is 0.5-1.0 mm.

[0023] Preferably, in step S2, the refining treatment includes using a refiner to blow a granular refining agent and an inert gas onto a sand casting mold of the aluminum alloy shell cone casting in a rotary spraying manner, and then performing a heat preservation treatment;

[0024] The refining treatment time is 15-20 minutes; the refining treatment temperature is 720-740°C;

[0025] After the refining treatment is completed, keep the temperature for 20-25 minutes;

[0026] The particle refining agent is ZS-AJ 401K ;

[0027] The inert gas is one or more of helium, argon, sulfur hexafluoride, and nitrogen.

[0028] Preferably, in step S3, the sand casting mold of the aluminum alloy shell cone casting is cooled to 680-700° C. before casting;

[0029] The casting process adopts a bottom injection differential pressure casting method, and the bottom injection differential pressure casting method is performed at a pouring temperature of 680-700°C;

[0030] The filling time is 30-60s, the pressure holding time is 600-1000s, and the casting is left to stand for 10-14h after solidification.

[0031] Preferably, in step S3, the heat treatment is performed by heating the cast aluminum alloy shell cone casting sand mold at 400-500°C for 1.5-2 hours, heating it to 533-543°C, and keeping it for 14-18 hours. Then, the aluminum alloy shell cone casting sand mold is placed in a 50-60°C water pool within 20-30 seconds until the water stops boiling.

[0032] Preferably, in step S3, the heat treatment is followed by aging treatment for 8-24 hours;

[0033] The aging treatment includes heating the sand casting mold of the cast aluminum alloy shell cone casting to 150-160° C., keeping the temperature for 8-10 hours, taking it out and air cooling it to obtain a finished casting.

[0034] Compared with the prior art, the present invention has at least the following technical effects:

[0035] The present invention provides a preparation process for a large-scale, high-performance, mushy solidified aluminum alloy shell cone casting. The process adopts a sand mold differential pressure casting method, selects a bottom-pouring slot-type pouring system, prepares a mold according to a pouring system design drawing verified by PROCAST simulation software, and then performs mold preparation, alloy smelting, differential pressure casting, sand cleaning, cutting and pouring risers, casting processing inspection and finishing, and T5 heat treatment to obtain a high-performance, mushy solidified aluminum alloy shell cone casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the experimental results of Comparative Example 1;

[0037] Figure 2 Schematic diagram of the experimental results of Comparative Example 2;

[0038] Figure 3 Schematic diagram of experimental results of Comparative Example 3;

[0039] Figure 4 Schematic diagram of the experimental results of Comparative Example 3. DETAILED DESCRIPTION

[0040] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Specific conditions not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0041] Example 1:

[0042] Analysis of the casting's structural characteristics: The casting is a typical body of revolution, with uniform wall thickness and a symmetrical structure, which facilitates the design and implementation of the casting process. The thick flanges at the large and small ends of the casting increase the thermal junctions in these locations, which can easily lead to casting defects. However, by installing appropriate chillers in these areas and reducing the thermal junctions, casting defects can be effectively avoided. Furthermore, the gating system design using slot runners and large risers for shrinkage feeding can achieve significant shrinkage feeding effects, reduce the likelihood of casting defects, and ensure casting quality.

[0043] A process for preparing a large, high-performance, paste-solidified aluminum alloy shell cone casting comprises the following steps:

[0044] Step S1: Design the gating system of the casting using 3D drawing software, perform numerical simulation with ProCast software, and optimize the gating system. Design and manufacture a sand casting mold for the aluminum alloy shell cone casting based on the gating system. The shrinkage rate of the core box design is 0.8%, and the shrinkage rate of the exterior design is 1%.

[0045] Step S2: Apply a release agent to the working surface of the casting mold prepared in step S1. Clean the mold and sand box and apply a release agent to the mold. Place the mold, chiller, and sand box on a molding platform according to the casting mold preparation process diagram. Use a sand mixer with a sand mixing efficiency of 20t / h to perform molding. The ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%. Transfer the mold to the sand box and demould it after vibrating and leaving it for 2-4 hours. Make a 10mm Φ vent hole at the top of each riser. Use an automated molding equipment with a sand mixing efficiency of 20t / h to perform molding. The ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%.

[0046] Step S3: After applying a layer of paint on the surface of the sand mold and core, let it stand for 30 minutes. After it is naturally dry, apply a second layer of paint. The thickness of the paint is controlled at 0.3-0.5mm. After applying the paint, bake the mold in an oven at 160℃×2h.

[0047] Step S4: Melting ZL205A or ZL305A or other paste-solidifying alloys, using a sodium-free refining agent and inert gas rotary injection for 20 minutes in accordance with environmental protection requirements, with a refining temperature of 720-730°C; after refining, heat preservation for 20 minutes, and then cooling to 690±10°C for casting.

[0048] Step S5: adopting a bottom injection differential pressure casting method.

[0049] Step S6: After the casting is processed, inspected and trimmed, it is subjected to T5 heat treatment.

[0050] Test results: Test report:

[0051] Test number: 22TN-285-1. Sample quality: Material: ZL205A, Condition: T5 Cast, Process: S, Specification: Ø6. 3 samples.

[0052]

[0053]

[0054] X-ray inspection results of castings

[0055]

[0056]

[0057] Example 2:

[0058] Analysis of the structural characteristics of the casting: The casting is a typical rotating body casting. The main casting difficulty is that the diameter of the large end of the casting is 1200mm, the height is 970mm, and the thickness of the large and small end flanges of the casting exceeds 50mm, which increases the hot spot at this position of the casting and easily forms casting defects. It is difficult to meet the mechanical properties Rm ≥ 440MPa, A ≥ 4%, and internal quality Class I casting requirements.

[0059] Step S1: Based on the structural characteristics of the casting, the casting gating system is designed using 3D drawing software. Numerical simulation is performed with ProCast software to optimize the gating system. A sand casting mold for the aluminum alloy shell cone casting is manufactured according to the gating system design drawings. The shrinkage rate of the core box design is 0.75%, and the shrinkage rate of the exterior design is 0.95%.

[0060] Step S2: smear release agent on the casting mold working surface prepared by step S1, mold and sand box are cleaned up, and mold is coated with release agent on mold. According to the casting mold preparation process diagram, mold, cold iron, and sand box are placed on the molding platform. A sand mixer with a sand mixing efficiency of 20t / h is adopted to carry out molding. wherein the ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%. Change over to the sand box, place the demoulding after (2-4)h after vibration. 1 Φ10mm vent hole is made on each riser top. An automated molding equipment with a sand mixing efficiency of 20t / h is adopted to carry out molding. wherein the ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%.

[0061] Step S3: After applying a layer of paint on the surface of the sand mold and core, let it stand for 30 minutes. After it is naturally dry, apply a second layer of paint. The thickness of the paint is controlled at (0.3-0.5) mm. After applying the paint, bake the mold in an oven at 160℃×2h.

[0062] Step S4: Melting ZL205A or ZL305A or other paste-solidifying alloys, using a sodium-free refining agent and inert gas rotary injection for 20 minutes in accordance with environmental protection requirements, with a refining temperature of 720-730°C; after refining, heat preservation for 20 minutes, and then cooling to 690±10°C for casting.

[0063] Step S5: adopting a bottom injection differential pressure casting method.

[0064] Step S6: After the casting is processed, inspected and trimmed, it is subjected to T5 heat treatment.

[0065] Test results: Test report:

[0066] Test number: 22TN-285-3. Sample quality: Material: ZL205A, Condition: T5 Cast, Finish: S, Specification: Ø6. 6 samples. Batch / Serial Number: P1-22008-01.

[0067]

[0068] X-ray inspection results of castings

[0069]

[0070]

[0071]

[0072]

[0073] Experimental Example 3:

[0074] Based on the structural characteristics of the casting, the casting's gating system was designed using 3D drawing software, and numerical simulation was performed with ProCast software to optimize the gating system. A sand casting mold for the aluminum alloy shell cone casting was manufactured according to the gating system design drawings. The shrinkage rate of the core box design was 0.8%, and the shrinkage rate of the exterior design was 1%.

[0075] Step S2: smear release agent on the casting mold working surface prepared by step S1, mold and sand box are cleaned up, and mold is coated with release agent on mold. According to the casting mold preparation process diagram, mold, cold iron, and sand box are placed on the molding platform. A sand mixer with a sand mixing efficiency of 20t / h is adopted to carry out molding. wherein the ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%. Change over to the sand box, place the demoulding after (2-4)h after vibration. 1 Φ10mm vent hole is made on each riser top. An automated molding equipment with a sand mixing efficiency of 20t / h is adopted to carry out molding. wherein the ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%.

[0076] Step S3: After applying a layer of paint on the surface of the sand mold and core, let it stand for 30 minutes. After it is naturally dry, apply a second layer of paint. The thickness of the paint is controlled at (0.3-0.5) mm. After applying the paint, bake the mold in an oven at 160℃×2h.

[0077] Step S4: Melting ZL205A or ZL305A or other paste-solidifying alloys, using a sodium-free refining agent and inert gas rotary injection for 20 minutes in accordance with environmental protection requirements, with a refining temperature of 720-730°C; after refining, heat preservation for 20 minutes, and then cooling to 690±10°C for casting.

[0078] Step S5: adopting a bottom injection differential pressure casting method.

[0079] Step S6: After the casting is processed, inspected and trimmed, it is subjected to T5 heat treatment.

[0080] Test results: Test report:

[0081] Batch / Code: P2207-090 (Casting 3).

[0082]

[0083]

[0084] X-ray inspection results of castings

[0085]

[0086]

[0087] Comparative Example 1: The difference from Implementation Case 1 is in step S2.

[0088] The casting mold working surface prepared by step S1 is smeared with a release agent. Mould and sand box are cleaned up. Mould is coated with a release agent. Mould, chiller and sand box are placed on a moulding platform according to the casting mold preparation process diagram. A sand mixer with a sand mixing efficiency of 20t / h is adopted to carry out moulding. The ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%. The sand box is transferred to the casting mold. The working surface is not completely coated with a coating. After vibrating, the mould is demoulded after placing for 2-4h. A 10mm Φ vent is made at each riser top. An automated moulding equipment with a sand mixing efficiency of 20t / h is adopted to carry out moulding. The ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%.

[0089] like Figure 1 As shown in the figure, the final casting has problems such as excessive surface roughness, and some areas are missing meat after processing, which cannot meet the technical requirements. Specifically, the missing meat is caused by an inappropriate casting preparation process.

[0090] Comparative Example 2: The difference from Implementation Example 2 is in step S5.

[0091] like Figure 2 As shown, the differential pressure casting method was not adopted, but gravity casting was adopted, which resulted in serious problems in the final casting such as incomplete filling and poor internal quality.

[0092] Comparative Example 3: The difference from Implementation Case 3 is in step S4.

[0093] Use sodium-free refining agent and inert gas rotary blowing to refine for 10 minutes at a refining temperature of 720-730°C; after refining, keep warm for 20 minutes and cool to 705°C for casting.

[0094] like Figure 3 As shown, the final casting has many segregation problems;

[0095] like Figure 4 As shown in the figure, the inner wall of the casting finally produced has problems such as multiple loose spots.

[0096] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A process for preparing a large, high-performance, paste-like solidified aluminum alloy shell cone casting, characterized in that: The process adopts a sand mold differential pressure casting method and a bottom pouring slot type pouring system to obtain a high-performance paste-like solidified aluminum alloy shell cone casting; The specific steps include: S1. After applying a release agent to the working surface of the sand casting mold of the aluminum alloy shell cone casting, performing molding and cleaning treatments, and then continuing to apply paint on the working surface of the sand mold and drying; the molding treatment includes using molding equipment to perform sand mixing, flow coating, mold removal and box closing; In the molding agent, the ratio of furan resin to dry sand is 0.8%, and the ratio of curing agent to furan resin is 30%; The cleaning process includes sand removal, drying and mold closing; The drying temperature is 150-160℃ and the drying time is 1.5-2h; The coating that is continuously applied on the working surface of the sand mold is a graphite-based coating, and the coating thickness is 0.5-1.0 mm; S2. Melt ZL205A or ZL305A paste-solidifying alloy. In accordance with environmental protection requirements, the refining process includes using a sodium-free refining agent and inert gas rotary injection for 20 minutes at a refining temperature of 720-730°C; after refining, keep the temperature for 20 minutes and cool it to 690±10°C for casting; The sodium-free refining agent is ZS-AJ 401K ; The inert gas is one or more of helium and argon; S3, cooling the sand casting mold of the aluminum alloy shell cone casting after the above refining treatment, and then performing casting, heat treatment and aging treatment to obtain a finished casting.

2. The process for preparing a large-scale high-performance mushy solidified aluminum alloy shell cone casting according to claim 1, characterized in that: In the step S1, the core box design shrinkage rate of the sand casting mold of the aluminum alloy shell cone casting is 0.75%-0.85%, and the exterior design shrinkage rate is 0.9%-1.05%.

3. The process for preparing a large-scale, high-performance, paste-solidified aluminum alloy shell cone casting according to claim 2, characterized in that: The core box design shrinkage rate is 0.8%, and the exterior design shrinkage rate is 1%.

4. The process for preparing a large-scale high-performance mushy solidified aluminum alloy shell cone casting according to claim 1, characterized in that: In the step S1, the release agent is applied with a thickness of 0.5 mm to 0.7 mm.

5. The process for preparing a large-scale high-performance mushy solidified aluminum alloy shell cone casting according to claim 1, characterized in that: In step S3, the sand casting mold of the aluminum alloy shell cone casting is cooled to 680-700° C. and then cast; The casting process adopts a bottom injection differential pressure casting method, and the bottom injection differential pressure casting method is performed at a pouring temperature of 680-700°C; The filling time is 30-60s, the pressure holding time is 600-1000s, and the casting is left to stand for 10-14h after solidification.

6. The process for preparing a large-scale, high-performance, pasty-solidified aluminum alloy shell cone casting according to claim 1, characterized in that: In step S3, the heat treatment is carried out by heating the paste-like solidified aluminum alloy casting blank prepared by pouring at 400-500°C for 1.5-2 hours, raising the temperature to 533-543°C, and keeping it for 14-18 hours. Then, the aluminum alloy casting blank is placed in a 50-60°C water pool within 20-30 seconds until the water stops boiling.

7. The process for preparing a large-scale, high-performance, pasty-solidified aluminum alloy shell cone casting according to claim 1, characterized in that: In step S3, the heat treatment is followed by standing for 8-24 hours; The aging treatment includes heating the paste-like solidified aluminum alloy casting prepared by casting to 150-160° C., keeping the temperature for 8-10 hours, taking it out and air-cooling it to obtain a finished casting.

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