Water-soluble core for light-weight aluminum casting and method for manufacturing the same

Abstract

The present application relates to the technical field of lightweight aluminum castings, and discloses a water-soluble core for lightweight aluminum castings and a preparation method thereof. The water-soluble core for lightweight aluminum castings is prepared from the following raw materials in parts by weight: 60-73 parts of salt powder, 15-26 parts of ceramic powder, and 10-18 parts of a catalyst. The salt powder is sodium chloride, the ceramic powder is a mixture of aluminum oxide and zirconium oxide, and the catalyst is microcrystalline paraffin wax. The water-soluble core produced by the present application is easy to clean, has a small gas evolution rate, and has a high-quality internal surface of the aluminum casting cavity and is environmentally friendly.

Description

Technical Field

[0001] This invention patent relates to the field of lightweight aluminum casting technology, and in particular to a water-soluble core for lightweight aluminum casting and its preparation method. Background Technology

[0002] Lightweight aluminum castings represent a development trend in the machinery industry. Weight reduction in aluminum castings is typically achieved through internal cavities, currently often created using sand cores. However, sand cores have limitations and drawbacks, such as surface coating residue, high gas generation, difficulty in cleaning, and environmental unfriendliness. To address these issues, a water-soluble core preparation method for lightweight aluminum castings has been developed. Summary of the Invention

[0003] In order to solve the problems of the prior art, this invention patent provides a water-soluble core for lightweight aluminum castings that is easy to clean, has low gas generation, high surface quality inside the cavity, and is environmentally friendly, as well as a method for its preparation.

[0004] This invention patent is achieved through the following technical solution: A lightweight aluminum casting water-soluble core is characterized by being made from the following raw materials in parts by weight: 60-73 parts by weight of salt powder, 15-26 parts by weight of ceramic powder, and 10-18 parts by weight of catalyst; the salt powder is sodium chloride; the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of (3-5):1; and the catalyst is microcrystalline wax.

[0005] The method for preparing a water-soluble core for lightweight aluminum castings according to the present invention includes the following steps: The first step is to inspect and weigh the raw materials; Step 2, Mixing: Place the weighed raw materials into the mixer and mix them; mixing time: 3.5 hours to 5 hours; material tank temperature: 50℃ to 90℃; Step 3, placing bets: The mixed composite material is transferred to an injection molding machine for injection. The injection piston moves down to inject the composite material into the mold, holds the pressure, and removes the mold after molding. The injection pressure is 3~8MPa; the holding time is 250 seconds~600 seconds. Step 4, Finishing and heat treatment: Trimming involves trimming and removing parting lines from the semi-finished product after injection molding. 1. The finished semi-finished products are transferred to heat treatment equipment for heat treatment. The heat treatment adopts a stepped heating method: from room temperature to 150℃ within 30-60 minutes, and hold at 150℃ for 30-120 minutes; from 150℃ to 250℃ within 30-60 minutes, and hold at 250℃ for 30-120 minutes; from 250℃ to 350℃ within 30-60 minutes, and hold at 350℃ for 30-120 minutes; from 350℃ to 450℃ within 30-60 minutes, and hold at 450℃ for 30-120 minutes; from 450℃ to 550℃ within 30-60 minutes, and hold at 550℃ for 30-120 minutes; from 550℃ to 750℃ within 30-60 minutes, and hold at 750℃ for 30-160 minutes; then cool with the furnace for about 8-20 hours; the product is removed after the temperature drops to 80-100℃.

[0006] The beneficial effects of this invention patent are: The water-soluble core prepared by this invention patent solves the problems of coating residue, large gas generation, and difficulty in cleaning on the surface of sand core castings. It is a lightweight water-soluble core for aluminum castings that is easy to clean, generates little gas, has high surface quality inside the cavity of aluminum castings, and is environmentally friendly. Attached Figure Description

[0007] The present invention will be further described below with reference to the accompanying drawings and tables: Figure 1 Process flow diagram for the preparation of water-soluble cores; Figure 2 This is a standard block used for testing the performance of the first type of raw material; Figure 3 This is a standard block for testing the performance of the second type of raw material; Figure 4 The tensile strength results are for three formulations under the same process. Figure 5 The tensile strength results for Formula 2 under different heat preservation times are shown. Detailed Implementation

[0008] Example 1 Step 1: Raw material processing This includes raw material inspection and weighing. Weighing is performed according to different proportions. A typical raw material formula is as follows (unit: kg): 60 kg salt powder, 26 kg ceramic powder, and 10 kg catalyst. The main component of the salt powder is sodium chloride; the main component of the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of 4:1; the main component of the catalyst is microcrystalline wax.

[0009] Step 2: Mixing The weighed raw materials are placed into the mixing tank of the mixer for mixing. A typical mixing process is as follows: mixing time: 3.5 hours; tank temperature: 90℃.

[0010] Third step: Injection: The mixed composite material is transferred to the injection molding machine barrel for injection. The injection piston moves downward to inject the composite material into the mold, maintains pressure, and removes the molded product. A typical process is as follows: injection pressure 4 MPa; holding time: 400 seconds.

[0011] Step 4: Finishing and heat treatment: The semi-finished product after injection molding needs to be trimmed to remove the parting line. The trimmed semi-finished product is then transferred to a heat treatment unit for heat treatment. The heat treatment uses a stepped heating process, with the typical steps as follows: 30 minutes from room temperature to 150°C, hold at 150°C for 60 minutes; 40 minutes from 150°C to 250°C, hold at 250°C for 50 minutes; 30 minutes from 250°C to 350°C, hold at 350°C for 70 minutes; 40 minutes from 350°C to 450°C, hold at 450°C for 60 minutes; 30 minutes from 450°C to 550°C, hold at 550°C for 60 minutes; 40 minutes from 550°C to 750°C, hold at 750°C for 120 minutes; then cooled in the furnace for approximately 10 hours. The product is removed after the temperature drops to 100°C.

[0012] Example 2 Step 1: Raw material processing This includes raw material inspection and weighing. Weighing is performed according to different proportions. A typical raw material formula is as follows (unit: kg): 68 kg of salt powder, 20 kg of ceramic powder, and 18 kg of catalyst. The main component of the salt powder is sodium chloride; the main component of the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of 3:1; the main component of the catalyst is microcrystalline wax.

[0013] Step 2: Mixing The weighed raw materials are placed into the mixing tank of the mixer for mixing. A typical mixing process is as follows: mixing time: 6 hours; tank temperature: 50℃.

[0014] Third step: Injection: The mixed composite material is transferred to the injection molding machine barrel for injection. The injection piston moves downward to inject the composite material into the mold, maintains pressure, and removes the molded product. A typical process is as follows: injection pressure 5 MPa; holding time: 250 seconds.

[0015] Step 4: Finishing and heat treatment: The semi-finished product after injection molding needs to be trimmed to remove the parting line. The trimmed semi-finished product is then transferred to a heat treatment device for heat treatment. The heat treatment uses a stepped heating process, with the typical steps as follows: 40 minutes from room temperature to 150°C, hold at 150°C for 30 minutes; 40 minutes from 150°C to 250°C, hold at 250°C for 50 minutes; 50 minutes from 250°C to 350°C, hold at 350°C for 40 minutes; 50 minutes from 350°C to 450°C, hold at 450°C for 60 minutes; 40 minutes from 450°C to 550°C, hold at 550°C for 50 minutes; 40 minutes from 550°C to 750°C, hold at 750°C for 60 minutes; then cooled in the furnace for approximately 12 hours. The product is removed after the temperature drops to 80°C.

[0016] Example 3 Step 1: Raw material processing This includes raw material inspection and weighing. Weighing is performed according to different proportions. A typical raw material formula is as follows (unit: kg): 64 kg salt powder, 23 kg ceramic powder, and 14 kg catalyst. The main component of the salt powder is sodium chloride; the main component of the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of 5:1; the main component of the catalyst is microcrystalline wax.

[0017] Step 2: Mixing The weighed raw materials are placed into the mixing tank of the mixer for mixing. A typical mixing process is as follows: mixing time: 4 hours; tank temperature: 80℃.

[0018] Third step: Injection: The mixed composite material is transferred to the injection molding machine barrel for injection. The injection piston moves downward to inject the composite material into the mold, maintains pressure, and removes the molded material. A typical process is as follows: injection pressure 6 MPa; holding time: 350 seconds.

[0019] Step 4: Finishing and heat treatment: The semi-finished product after injection molding needs to be trimmed to remove the parting line. The trimmed semi-finished product is then transferred to a heat treatment device for heat treatment. The heat treatment uses a stepped heating method, with a typical process as follows: 50 min from room temperature to 150℃, hold at 150℃ for 40 min; 40 min from 150℃ to 250℃, hold at 250℃ for 50 min; 50 min from 250℃ to 350℃, hold at 350℃ for 60 min; 40 min from 350℃ to 450℃, hold at 450℃ for 120 min; 30 min from 450℃ to 550℃, hold at 550℃ for 80 min; 30 min from 550℃ to 750℃, hold at 750℃ for 90 min; then cooled in the furnace for approximately 13 hours. The product is removed after the temperature drops to 80℃.

[0020] Example 4 Step 1: Raw material processing This includes raw material inspection and weighing. Weighing is performed according to different proportions. A typical raw material formula is as follows (unit: kg): 65 kg salt powder, 20 kg ceramic powder, and 12 kg catalyst. The main component of the salt powder is sodium chloride; the main component of the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of 4:1; the main component of the catalyst is microcrystalline wax.

[0021] Step 2: Mixing The weighed raw materials are placed into the mixing tank of the mixer for mixing. A typical mixing process is as follows: mixing time: 5 hours; tank temperature: 60℃.

[0022] Third step: Injection: The mixed composite material is transferred to the injection molding machine barrel for injection. The injection piston moves downward to inject the composite material into the mold, maintains pressure, and removes the molded product. A typical process is as follows: injection pressure 3MPa; holding time: 500 seconds.

[0023] Step 4: Finishing and heat treatment: The semi-finished product after injection molding needs to be trimmed to remove the parting line. The trimmed semi-finished product is then transferred to a heat treatment device for heat treatment. The heat treatment uses a stepped heating method, with a typical process as follows: 60 minutes from room temperature to 150°C, hold at 150°C for 100 minutes; 40 minutes from 150°C to 250°C, hold at 250°C for 80 minutes; 60 minutes from 250°C to 350°C, hold at 350°C for 120 minutes; 40 minutes from 350°C to 450°C, hold at 450°C for 100 minutes; 60 minutes from 450°C to 550°C, hold at 550°C for 80 minutes; 60 minutes from 550°C to 750°C, hold at 750°C for 160 minutes; then cooled in the furnace for approximately 15 hours. The product is removed after the temperature drops to 90°C.

[0024] Example 5 Step 1: Raw material processing This includes raw material inspection and weighing. Weighing is performed according to different proportions. A typical raw material formula is as follows (unit: kg): 73 kg salt powder, 15 kg ceramic powder, and 15 kg catalyst. The main component of the salt powder is sodium chloride; the main component of the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of alumina to zirconium oxide of 5:1; the main component of the catalyst is microcrystalline wax.

[0025] Step 2: Mixing The weighed raw materials are placed into the mixing tank of the mixer for mixing. A typical mixing process is as follows: mixing time: 4 hours; tank temperature: 70℃.

[0026] Third step: Injection: The mixed composite material is transferred to the injection molding machine barrel for injection. The injection piston moves downward to inject the composite material into the mold, maintains pressure, and removes the molded product. A typical process is as follows: injection pressure 4 MPa; holding time: 600 seconds.

[0027] Step 4: Finishing and heat treatment: The semi-finished product after injection molding needs to be trimmed to remove the parting line. The trimmed semi-finished product is then transferred to a heat treatment device for heat treatment. The heat treatment uses a stepped heating method, with a typical process as follows: 50 min - from room temperature to 150℃, hold at 150℃ for 100 min; 50 min - from 150℃ to 250℃, hold at 250℃ for 80 min; 40 min - from 250℃ to 350℃, hold at 350℃ for 60 min; 40 min - from 350℃ to 450℃, hold at 450℃ for 110 min; 50 min - from 450℃ to 550℃, hold at 550℃ for 80 min; 60 min - from 550℃ to 750℃, hold at 750℃ for 30 min; then cooled in the furnace for approximately 12 hours. The product is removed after the temperature drops to 100℃.

[0028] Example 6: 65 kg of salt powder, 20 kg of ceramic powder, 15 kg of catalyst, the rest is the same as in Example 1.

[0029] Example 7: 70 kg of salt powder, 18 kg of ceramic powder, 12 kg of catalyst, the rest is the same as in Example 1.

[0030] Example 8: 73 kg of salt powder, 15 kg of ceramic powder, 12 kg of catalyst, the rest is the same as in Example 1.

[0031] II. Water-soluble core performance verification process, mainly verifying tensile strength. 1. Verify the effect of water-soluble components in different formulations on tensile strength under the same process (maximum holding time at heat treatment is 30 min): The mass fractions of each component in different formulations are as follows (Examples 6-8): Formula 1: 65 kg salt powder, 20 kg ceramic powder, 15 kg catalyst.

[0032] Formula 2: 70 kg salt powder, 18 kg ceramic powder, 12 kg catalyst.

[0033] Formula 3: 73 kg salt powder, 15 kg ceramic powder, 12 kg catalyst.

[0034] The tensile strength results for the three formulations under the same process are as follows: tensile strengths of 1.65 MPa, 2.26 MPa, and 1.93 MPa, respectively. (See...) Figure 4 .

[0035] According to relevant data verification, Formula 2 has the best tensile strength, approximately 2.26 MPa.

[0036] 2. Formula 2 was selected to verify the effect of different heat treatment processes, i.e., different holding times at the highest temperature, on the tensile strength of the water-soluble core: Process 1: Maximum temperature 750℃, holding time 30 minutes; (This has been verified) Process 2: Maximum temperature 750℃, holding time 60min; Process 3: Maximum temperature 750℃, holding time 90min; Process 4: Maximum temperature 750℃, heat preservation time 120min.

[0037] The tensile strength results of Formula 2 under different heat preservation times are shown in the figure. Figure 5 .

[0038] Based on relevant data verification, it can be concluded that the maximum heat preservation time has a direct impact on the tensile strength of the water-soluble core. As the heat preservation time increases, the tensile strength of the water-soluble core tends to increase. When the heat preservation time is 90 minutes, the tensile strength is the highest at 3.12 MPa. Further extending the heat preservation time does not significantly improve the tensile strength of the water-soluble core. The difference in tensile strength between the 60-minute and 90-minute heat preservation times is small (approximately 0.2 MPa). Under the premise of meeting the performance requirements of the water-soluble core, a trade-off can be made between the two to reduce costs and improve efficiency.

[0039] Except for the technical features described in the specification, all other technical features are known to those skilled in the art.

Claims

1. A water-soluble core for lightweight aluminum castings, characterized in that, It is made from the following raw materials in parts by weight: 60-73 parts salt powder, 15-26 parts ceramic powder, and 10-18 parts catalyst; the salt powder is sodium chloride; the ceramic powder is a mixture of alumina and zirconium oxide, with a mass ratio of (3-5):1; the catalyst is microcrystalline wax. The method for preparing the water-soluble core of this lightweight aluminum casting includes the following steps: The first step is to inspect and weigh the raw materials; Step 2, Mixing: Place the weighed raw materials into the mixer and mix; mixing time: 3.5 hours to 6 hours; material tank temperature: 50℃ to 90℃; Step 3, placing bets: The mixed composite material is transferred to an injection molding machine for injection. The injection piston moves down to inject the composite material into the mold, holds the pressure, and removes the mold after molding. The injection pressure is 3~8MPa; the holding time is 250 seconds~600 seconds. Step 4, Finishing and heat treatment: Trimming involves trimming and removing parting lines from the semi-finished product after injection molding. The finished semi-finished products are transferred to heat treatment equipment for heat treatment. The heat treatment adopts a stepped heating method: from room temperature to 150℃ within 30-60 minutes, and hold at 150℃ for 30-120 minutes; from 150℃ to 250℃ within 30-60 minutes, and hold at 250℃ for 30-120 minutes; from 250℃ to 350℃ within 30-60 minutes, and hold at 350℃ for 30-120 minutes; from 350℃ to 450℃ within 30-60 minutes, and hold at 450℃ for 30-120 minutes; from 450℃ to 550℃ within 30-60 minutes, and hold at 550℃ for 30-120 minutes; from 550℃ to 750℃ within 30-60 minutes, and hold at 750℃ for 30-160 minutes; then cooled in the furnace for 8-20 hours; the product is removed after the temperature drops to 80-100℃.

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