Multi-layer composite silica sol fired mold precision casting mold

Abstract

The invention provides a multi-layer composite silica sol fired mold precision casting mold. The multi-layer composite silica sol fired mold precision casting mold comprises a coating, a fired mold and a coating layering control system, and the coating is formed by compounding the following components: 20%-30% of silica sol, 10%-15% of nano silica, 5%-10% of nano aluminum oxide, 10%-20% of a modified polymer, 2%-5% of nano carbon fibers and 40%-50% of silica powder. The coating process of the coating is accurately controlled through a micro-spraying technology, and the uniformity of the coating is ensured. According to the multi-layer composite silica sol precision investment casting mold, the coating process is accurately controlled through the micro-spraying technology, the uniformity of a coating is effectively ensured, and particularly the problem that the coating is not uniform when a thick coating is manufactured can be solved. Due to the self-repairing function of the coating material, microcracks appearing at high temperature can be automatically repaired, so that the service life of the mold is prolonged, and casting defects caused by the cracks are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of casting moulds, in particular to a multi-layer composite silica sol investment pattern precision casting mould. Background Art

[0002] The multi-layer composite silica sol investment casting mold is mainly composed of investment mold, coating and support structure. First, the investment mold is usually made of wax mold or other fusible materials to replicate the shape of the casting. Its surface smoothness is crucial to the accuracy of the casting. Then, the surface of the investment mold is coated with a coating of silica sol mixed with sand many times, and each layer of coating is sintered to form a solid ceramic shell. These coatings can withstand the pouring of high-temperature metal and ensure the precise molding of the casting. The support structure plays a role in stabilizing the mold and is usually made of high-temperature resistant metal materials to ensure that the mold does not deform at high temperatures. The entire casting process melts the investment mold by heating, leaving a cavity for metal pouring, and obtains a high-precision casting after cooling.

[0003] Although this system has significant advantages in precision casting, it also has some drawbacks, mainly including uneven coating, residual mold, and difficulty in ensuring the uniformity of the coating, especially in the production process of thick coatings, which may lead to poor thermal stability and affect the quality of castings. In the melting process, the mold, such as wax mold, is prone to incomplete combustion, and the residue may contaminate the surface of the casting and reduce the accuracy of the casting. Since the coating needs to be applied and sintered multiple times, the production cycle is long, which affects the efficiency of large-scale production. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a multi-layer composite silica sol investment casting mold, which solves the problems of uneven coating, investment mold residue, the need for multiple coating and sintering, and a long production cycle, which affects the efficiency of large-scale production.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a multi-layer composite silica sol investment mold for precision casting, comprising: a coating, an investment mold, and a coating layering control system;

[0006] The coating is composited with the following ingredients: 20%-30% silica sol, 10%-15% nano silicon dioxide, 5%-10% nano aluminum oxide, 10%-20% modified polymer, 2%-5% nano carbon fiber, 40%-50% silicon dioxide powder. The coating is precisely controlled by micro-spraying technology to ensure the uniformity of the coating. The coating has a self-repairing function. When micro-cracks appear in the coating, it can be automatically repaired at high temperature, thereby extending the service life of the mold and reducing casting defects caused by cracks.

[0007] The investment mold is composed of the following ingredients: 30%-45% polymer-based composite material, 25%-35% nano mineral filler, 10%-15% high melting point metal oxide, and 5%-10% reinforcing fiber. The investment mold can be melted quickly at high temperature, and no harmful gas or residue is generated during the melting process, thus avoiding the pollution problem caused by traditional wax molds. By accurately controlling the thermal expansion coefficient between the investment mold and the coating, mold cracking or deformation caused by thermal stress is reduced.

[0008] The coating layering control system monitors the temperature, humidity and spraying amount of the coating in real time through a feedback adjustment system to ensure the uniformity of each layer of coating and the stability of the sintering process. The coating layering control system can automatically adjust the spraying amount and drying time according to the thickness and material of the coating, thereby avoiding uneven coating and defects in the sintering process.

[0009] Preferably, the coating is applied by micro-spraying technology, which uses air spraying or electrostatic spraying, wherein electrostatic spraying has higher coating adhesion and uniformity.

[0010] Preferably, the modified polymer in the coating material is one or more of epoxy resin, polyurethane resin or acrylic resin, the particle size of the nano silicon dioxide is 5-30 nanometers, and the particle size of the nano aluminum oxide is 10-50 nanometers.

[0011] Preferably, the thickness of the coating is 1-5 mm, and the self-repairing function of the coating is that it can automatically fill microcracks at high temperatures, and the repair time does not exceed 10 minutes.

[0012] Preferably, the polymer-based composite material in the investment pattern material is epoxy resin, polyethylene or polypropylene, the high melting point metal oxide is one or more of aluminum oxide, zirconium oxide or titanium oxide, the melting temperature of the investment pattern material at high temperature is 150°C-500°C, and the melting process does not produce toxic gases or residues.

[0013] Preferably, the coating layering control system includes a temperature sensor, a humidity sensor, a spraying amount sensor and an automatic drying time adjustment module. The spraying amount sensor can adjust the spraying amount in real time according to the coating thickness and the type of coating material to ensure the uniformity of the coating.

[0014] Preferably, the outer coating of the mold has higher high temperature resistance, and its high temperature resistance range is 800°C-1000°C, and the inner coating has a lower expansion coefficient, which can effectively cope with the thermal stress of the mold.

[0015] Preferably, the thermal expansion coefficient matching design between the coating and the investment mold is: the thermal expansion coefficient of the inner coating is 2×10 -6 / K to 4×10-6 / K, the thermal expansion coefficient of the outer coating is 5×10 -6 / K to 7×10 -6 / K.

[0016] The present invention provides a multi-layer composite silica sol investment casting mold.

[0017] Beneficial effects:

[0018] This multi-layer composite silica sol investment casting mold uses micro-spraying technology to accurately control the coating process, effectively ensuring the uniformity of the coating, especially when making thick coatings, it can avoid the problem of uneven coating. The self-repairing function of the coating material enables microcracks that appear at high temperatures to be automatically repaired, thereby extending the service life of the mold and reducing casting defects caused by cracks. In addition, the investment material can melt quickly without producing harmful gases or residues, avoiding the pollution problems caused by traditional wax molds. At the same time, by accurately controlling the thermal expansion coefficient between the coating and the investment mold, the mold cracking or deformation caused by thermal stress is reduced, ensuring the stability and efficient operation of the mold.

[0019] The coating layering control system can monitor the temperature, humidity and spraying amount of the coating in real time to ensure the uniformity of each layer of coating and the stability of the sintering process, and automatically adjust the spraying amount and drying time to avoid uneven coating and defects in the sintering process, thereby improving production efficiency and shortening the production cycle to meet the needs of large-scale production. The optimized thermal expansion coefficient between the coating and the investment pattern enables the inner and outer coatings to effectively cope with thermal stress in high-temperature environments and avoid deformation or cracking of the mold. The outer coating has high high-temperature resistance, which further improves the durability of the mold in high-temperature casting. These advantages enable this technical solution to significantly improve the performance and production efficiency of casting molds, providing a more efficient and reliable solution for the field of precision casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scoring diagram for the technology of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a multi-layer composite silica sol investment mold for precision casting, including a coating, an investment mold, and a coating layering control system;

[0023] The coating is composed of the following ingredients: 25% silica sol, 10% nano silicon dioxide, 10% nano aluminum oxide, 10% modified polymer, 5% nano carbon fiber, 40% silicon dioxide powder. The coating is precisely controlled by micro-spraying technology to ensure the uniformity of the coating. The coating has a self-repairing function. When micro-cracks appear in the coating, it can automatically repair at high temperature, extend the service life of the mold, and reduce casting defects caused by cracks. The coating is applied by micro-spraying technology, which adopts air spraying or electrostatic spraying. Among them, electrostatic spraying has higher coating adhesion and uniformity. The modified polymer in the coating material is one or more of epoxy resin, polyurethane resin or acrylic resin. The particle size of nano silicon dioxide is 5-30 nanometers, the particle size of nano aluminum oxide is 10-50 nanometers, and the thickness of the coating is 1-5 mm. The self-repairing function of the coating is that it can automatically fill micro-cracks at high temperature, and the repair time does not exceed 10 minutes.

[0024] The investment mold is composed of the following ingredients: 45% polymer-based composite material, 30% nano-mineral filler, 15% high-melting-point metal oxide, and 10% reinforcing fiber. The investment mold can melt quickly at high temperatures, and no harmful gas or residue is produced during the melting process, avoiding the pollution problem caused by traditional wax molds. By precisely controlling the thermal expansion coefficient between the investment mold and the coating, the mold cracking or deformation caused by thermal stress is reduced. The polymer-based composite material in the investment mold material is epoxy resin, polyethylene or polypropylene, and the high-melting-point metal oxide is one or more of aluminum oxide, zirconium oxide or titanium oxide. The melting temperature of the investment mold material at high temperature is 150℃-500℃, and no toxic gas or residue is produced during the melting process.

[0025] The coating layering control system monitors the temperature, humidity and spraying amount of the coating in real time through the feedback adjustment system to ensure the uniformity of each layer of coating and the stability of the sintering process. The coating layering control system can automatically adjust the spraying amount and drying time according to the thickness and material of the coating, thereby avoiding uneven coating and defects in the sintering process. The coating layering control system includes a temperature sensor, a humidity sensor, a spraying amount sensor and an automatic drying time adjustment module. The spraying amount sensor can adjust the spraying amount in real time according to the coating thickness and the type of coating material to ensure the uniformity of the coating. The outer coating of the mold has higher high temperature resistance, and its high temperature resistance range is 1000℃. The inner coating has a lower expansion coefficient, which can effectively cope with the thermal stress of the mold. The thermal expansion coefficient matching design between the coating and the investment mold is: the thermal expansion coefficient of the inner coating is 2×10 -6 / K to 4×10 -6 / K, the thermal expansion coefficient of the outer coating is 5×10 -6 / K to 7×10 -6 / K.

[0026] Experimental Example:

[0027] Experimental steps and parameters

[0028] 1. Coating preparation and application

[0029] Step 1: Prepare the coating materials

[0030] Prepare coating materials:

[0031] Silica sol: 25%

[0032] Nano silicon dioxide: 10%

[0033] Nano aluminum oxide: 10%

[0034] Modified polymer epoxy resin: 10%

[0035] Nanocarbon fiber: 5%

[0036] Silicon dioxide powder: 40%

[0037] The above materials are mixed evenly by mechanical stirring to ensure that the nanomaterials are fully dispersed and avoid agglomeration.

[0038] Step 2: Spray coating

[0039] Use micro-spraying technology (electrostatic spraying method) to coat the mold surface:

[0040] Spraying equipment: electrostatic spraying device, spraying pressure is set to 4 bar, spraying distance: 200 mm.

[0041] Spraying amount: set to 250g / m 2 , the spraying amount of each layer of coating is adjusted according to the coating thickness.

[0042] After each spraying, the coating was dried using a temperature and humidity control device, with the drying temperature set at 50 °C and the drying time set at 30 min.

[0043] Step 3: Multilayer coating and sintering

[0044] Coating thickness: 5mm, the coating is sprayed in multiple times to ensure that each layer is evenly covered.

[0045] Each layer of coating needs to be dried for at least 30 minutes, and then sintered at 1000℃ for 2 hours to ensure good adhesion and uniformity of the coating.

[0046] The sintering process is continuously monitored to ensure stable temperature and humidity.

[0047] 2. Investment Pattern Preparation

[0048] Step 1: Prepare the Investment Material

[0049] Prepare the investment pattern raw material according to the following ratio:

[0050] Polymer-based composite epoxy resin: 45%

[0051] Nano mineral filler silica: 30%

[0052] High melting point metal oxides Alumina: 15%

[0053] Reinforced fiber Carbon fiber: 10%

[0054] After mixing, the investment pattern is formed using compression molding or injection molding technology, and the shape of the mold should meet the casting design requirements.

[0055] Step 2: Investment Molding and Processing

[0056] After the investment pattern is formed in the mold, it is heat treated: heated to 500°C, and the melting time is set to 30 minutes according to the material characteristics.

[0057] During the melting process, the generation of toxic gases at high temperatures should be avoided. By controlling the temperature and pressure, the melting of the investment mold can be ensured to be fast and clean.

[0058] 3. Debugging of coating layer control system

[0059] Step 1: System setup and debugging

[0060] During the coating spraying process, a coating layering control system is used to monitor various coating parameters in real time through temperature sensors, humidity sensors, spraying amount sensors and drying time automatic adjustment modules:

[0061] Temperature sensor set monitoring temperature range: 100℃

[0062] Humidity sensor setting monitoring humidity range: 50%

[0063] The spray volume sensor adjusts the spray volume in real time to ensure that each layer of coating is even.

[0064] The spraying amount automatic adjustment module automatically adjusts the spraying amount according to the coating thickness and material type.

[0065] 4. Thermal expansion coefficient test

[0066] Step 1: Prepare the test sample

[0067] Prepare the coating samples to ensure that the thermal expansion coefficients of the inner and outer coatings match:

[0068] Thermal expansion coefficient of inner coating: 2×10 -6 / K to 4×10 -6 / K

[0069] Thermal expansion coefficient of outer coating: 5×10 -6 / K to 7×10 -6 / K

[0070] Use a thermal expansion coefficient tester to measure and ensure that the thermal expansion coefficients of the inner and outer layers of the coating match to avoid deformation or cracking of the mold caused by thermal stress.

[0071] 5. Mould high temperature resistance test

[0072] Step 1: High temperature test

[0073] The coated mold is placed in a high temperature furnace for high temperature resistance test to simulate the high temperature environment during the casting process:

[0074] Test temperature: 800℃, 900℃, 1000℃, each temperature point is maintained for 2 hours.

[0075] Test the stability of the mold, surface cracks of the coating, and the physical properties of the mold.

[0076] 6. Casting precision and surface quality inspection

[0077] Step 1: Casting Test

[0078] The prepared mold is used for casting, and the casting material is aluminum alloy, steel alloy, etc., and high-temperature casting equipment is used for casting.

[0079] Set the casting temperature to 1300°C and the casting time to 60 minutes, which can be adjusted according to different metal materials.

[0080] Step 2: Casting quality inspection

[0081] Use high-precision three-dimensional coordinate measuring instruments to measure the surface dimensions of castings to ensure that the dimensional accuracy of castings is within the design tolerance range.

[0082] Use a metallographic microscope to observe the surface finish of the casting to ensure there are no defects such as cracks and pores.

[0083] Use a microhardness tester to measure the hardness of the casting surface to ensure that the strength of the casting meets the requirements.

[0084] 7. Result analysis and evaluation

[0085] Step 1: Data statistics and comparison

[0086] The quality differences between the mold of the present invention and the traditional wax mold castings are compared, including the surface quality, dimensional accuracy, casting defects, etc. of the castings.

[0087] Record parameters such as thermal stability of the mold in a high temperature environment and self-healing performance of the coating.

[0088] Step 2: Conclusion

[0089] According to the test results, the performance of the multi-layer composite silica sol investment mold precision casting mold of the present invention in terms of coating uniformity, investment mold performance, casting quality and mold high temperature resistance is evaluated, and conclusions are drawn.

[0090] Summary of main experimental parameters:

[0091] Coating ratio:

[0092] Silica sol: 25%

[0093] Nano silicon dioxide: 10%

[0094] Nano aluminum oxide: 10%

[0095] Modified polymer epoxy resin: 10%

[0096] Nanocarbon fiber: 5%

[0097] Silicon dioxide powder: 40%

[0098] Coating spraying parameters:

[0099] Spraying pressure: 4 bar

[0100] Spraying distance: 200mm

[0101] Spraying amount: 250g / m 2

[0102] Drying time per layer: 30 minutes

[0103] Sintering temperature: 1000℃

[0104] Sintering time: 2 hours

[0105] Investment material ratio:

[0106] Polymer-based composites: 45%

[0107] Nano mineral fillers: 30%

[0108] High melting point metal oxides: 15%

[0109] Reinforcement fiber: 10%

[0110] Melting temperature: 500℃

[0111] Melting time: 30 minutes

[0112] Coating thermal expansion coefficient:

[0113] Thermal expansion coefficient of inner coating: 2×10 -6 / K to 4×10 -6 / K

[0114] Thermal expansion coefficient of outer coating: 5×10 -6 / K to 7×10 -6 / K.

[0115] Through these experimental steps and parameters, the various properties of the multi-layer composite silica sol investment casting mold of the present invention can be fully verified to ensure that it plays a superior role in the casting process. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-layer composite silica sol investment casting mold, characterized in that: include: Coating, investment mold, coating layer control system; The coating is composited with the following ingredients: 20%-30% silica sol, 10%-15% nano silicon dioxide, 5%-10% nano aluminum oxide, 10%-20% modified polymer, 2%-5% nano carbon fiber, 40%-50% silicon dioxide powder. The coating is precisely controlled by micro-spraying technology to ensure the uniformity of the coating. The coating has a self-repairing function. When micro-cracks appear in the coating, it can be automatically repaired at high temperature, thereby extending the service life of the mold and reducing casting defects caused by cracks. The investment mold is composed of the following ingredients: 30%-45% polymer-based composite material, 25%-35% nano mineral filler, 10%-15% high melting point metal oxide, and 5%-10% reinforcing fiber. The investment mold can be melted quickly at high temperature, and no harmful gas or residue is generated during the melting process, thus avoiding the pollution problem caused by traditional wax molds. By accurately controlling the thermal expansion coefficient between the investment mold and the coating, mold cracking or deformation caused by thermal stress is reduced. The coating layering control system monitors the temperature, humidity and spraying amount of the coating in real time through a feedback adjustment system to ensure the uniformity of each layer of coating and the stability of the sintering process. The coating layering control system can automatically adjust the spraying amount and drying time according to the thickness and material of the coating, thereby avoiding uneven coating and defects in the sintering process.

2. A multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The coating is applied by micro-spraying technology, which adopts air spraying or electrostatic spraying, wherein electrostatic spraying has higher coating adhesion and uniformity.

3. A multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The modified polymer in the coating material is one or more of epoxy resin, polyurethane resin or acrylic resin, the particle size of the nano silicon dioxide is 5-30 nanometers, and the particle size of the nano aluminum oxide is 10-50 nanometers.

4. A multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The thickness of the coating is 1-5 mm, and the self-repairing function of the coating is that it can automatically fill micro cracks at high temperature, and the repair time does not exceed 10 minutes.

5. The multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The polymer-based composite material in the investment pattern material is epoxy resin, polyethylene or polypropylene, the high melting point metal oxide is one or more of aluminum oxide, zirconium oxide or titanium oxide, the melting temperature of the investment pattern material at high temperature is 150°C-500°C, and no toxic gas or residue is generated during the melting process.

6. The multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The coating layering control system includes a temperature sensor, a humidity sensor, a spraying amount sensor and a drying time automatic adjustment module. The spraying amount sensor can adjust the spraying amount in real time according to the coating thickness and the type of coating material to ensure the uniformity of the coating.

7. The multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The outer coating of the mold has higher high temperature resistance, and its high temperature resistance range is 800°C-1000°C. The inner coating has a lower expansion coefficient and can effectively cope with the thermal stress of the mold.

8. The multi-layer composite silica sol investment casting mold according to claim 1, characterized in that: The thermal expansion coefficient matching design between the coating and the investment mold is as follows: the thermal expansion coefficient of the inner coating is 2×10 -6 / K to 4×10 -6 / K, the thermal expansion coefficient of the outer coating is 5×10 -6 / K to 7×10 -6 / K.

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