Rapid forming process for silica sol precision casting mold

Abstract

The invention provides a rapid forming process for a silica sol precision casting mold. The rapid molding process of the silica sol precision casting mold comprises the following steps: a, preparing a silicon source and selecting tetraethoxysilane as a main raw material, b, mixing tetraethoxysilane, deionized water and ethanol according to a volume ratio of 1: 4: 2 on a magnetic stirrer with a stirring rate of 300rpm, adding a proper amount of an acidic catalyst, carrying out a hydrolysis reaction, controlling the reaction temperature at 25 DEG C and the reaction duration time at 2 hours, and cooling to room temperature to obtain the silica sol precision casting mold. The addition amount of the acid catalyst is 1% of the volume of the tetraethoxysilane, and 0.1 weight percent of sodium dodecyl benzene sulfonate is added as an organic surfactant so as to improve the dispersity and the forming uniformity of the silica sol. According to the rapid forming process of the silica sol precision casting mold, through a series of optimized preparation steps and innovative technical means, the problem that in the prior art, the mold size generates tiny deviation due to shrinkage in the sol-gel conversion process is remarkably solved.

Description

Technical Field

[0001] The invention relates to the technical field of rapid prototyping of precision casting moulds, in particular to a rapid prototyping process of a silica sol precision casting mould. Background Art

[0002] The rapid prototyping process of silica sol precision casting mold mainly includes four basic steps: preparation of silica sol, mold design and rapid prototyping, mold curing and drying, and precision casting. First, high-purity silica sol is prepared by the sol-gel method, usually using tetraethoxysilane to undergo hydrolysis and condensation reactions under the action of water and a catalyst (such as an acid or base) to form a stable sol system. Next, the three-dimensional model of the mold is designed using computer-aided design software, and the design is converted into a physical mold through rapid prototyping technology. The silica sol is accurately deposited or solidified in this process to form the basic shape of the mold. The molded silica sol mold needs to be cured and dried under specific conditions to enhance its mechanical strength and stability. Finally, the cured and dried mold is used for precision casting, and the molten metal is injected into the mold, and after cooling, a metal part with high dimensional accuracy and excellent surface quality is obtained.

[0003] Although the rapid prototyping process of silica sol precision casting molds has significant advantages in terms of precision and efficiency in mold manufacturing, there are still some shortcomings in practical applications. Shrinkage may occur during the sol-gel conversion process, especially in the drying stage, resulting in slight deviations in mold dimensions, thus affecting the accuracy and consistency of the casting. Silica sol-based molds are usually highly brittle and easily cracked or damaged under mechanical shock or temperature changes, limiting their application in high-load or complex casting processes. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a rapid prototyping process for silica sol precision casting molds, which solves the problem of slight deviations in mold size caused by shrinkage during the sol-gel conversion process. Silica sol-based molds are highly brittle and easily cracked or damaged under mechanical shock or temperature changes, limiting their application in high-load or complex casting processes.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a silica sol precision casting mold rapid prototyping process, comprising:

[0006] a. Prepare a silicon source and select tetraethoxysilane as the main raw material;

[0007] b. On a magnetic stirrer at a stirring rate of 300 rpm, tetraethoxysilane, deionized water and ethanol were mixed in a volume ratio of 1:4:2, and an appropriate amount of an acidic catalyst was added for hydrolysis reaction. The reaction temperature was controlled at 25°C for 2 hours to generate a silica sol;

[0008] c. Adjust the pH value of silica sol to 5.0 and use ammonia or hydrochloric acid for fine-tuning;

[0009] d. Use computer-aided design software to design the three-dimensional model of the required mold;

[0010] e. Use digital light processing rapid prototyping equipment to convert the designed 3D model into a physical mold;

[0011] f. In the DLP device, set the exposure time to 5 seconds / layer and the layer thickness to 50 microns, accurately deposit and photo-cure the silica sol to form the basic shape of the mold;

[0012] g. Pre-curing the formed silica sol mold in an oven at 60°C for 4 hours to reduce shrinkage during the subsequent drying process;

[0013] h. Place the pre-cured mold in a thermal cycle oven for curing at a temperature of 150°C for 6 hours to transform it into a solid gel structure;

[0014] i. Use multi-step progressive drying technology, the first step is drying at 40℃ for 2 hours, the second step is drying at 60℃ for 2 hours, and the third step is drying at 80℃ for 2 hours, so as to gradually reduce humidity and reduce drying shrinkage;

[0015] j. Treat the mold surface after curing and drying by coating a layer of polydimethylsiloxane reinforcing agent with a coating thickness of 0.5 mm to improve the mechanical strength and crack resistance of the mold;

[0016] k. Place the surface treated mold in a heat treatment furnace for heat treatment. The heat treatment temperature is set at 700°C for 2 hours to improve the temperature resistance and durability of the mold.

[0017] l. Apply the treated silica sol mold to the precision casting process, preheat the mold to 200°C, then inject molten metal into the mold, and obtain high-precision metal castings after cooling.

[0018] Preferably, the amount of the acidic catalyst added in step b is 1% by volume of tetraethoxysilane, 0.1 weight percent of sodium dodecylbenzene sulfonate is added in step b as an organic surfactant to improve the dispersibility and molding uniformity of the silica sol, and the pH value in step c is adjusted in the range of 4.8 to 5.2.

[0019] Preferably, the deposition rate in step f is controlled at 10 μm / s to ensure the geometric accuracy of the mold. A dual light source irradiation system is used in step f, including ultraviolet light and visible light, to improve the photocuring efficiency and the molding speed of the mold. The pre-curing treatment in step g is carried out in a constant temperature oven, and the humidity of the oven is controlled at 20% RH. The curing treatment in step h uses ultraviolet radiation to assist curing to accelerate the gelation process and reduce shrinkage.

[0020] Preferably, after each drying step in the multi-step progressive drying technology in step i, the mold needs to be cooled at room temperature for 30 minutes to avoid stress caused by sudden temperature change. The multi-step progressive drying technology in step i further includes performing ultrasonic vibration treatment after each drying step to eliminate tiny bubbles inside the mold and improve the density and uniformity of the mold. The ratio of the polydimethylsiloxane enhancer in step j is a volume ratio of polydimethylsiloxane to solvent of 1:10.

[0021] Preferably, during the heat treatment process in step k, the atmosphere in the furnace is an inert gas atmosphere to prevent oxidation of the mold surface. The heat treatment process in step k includes preheating the mold to 300°C before heat treatment to eliminate residual stress inside the mold and further improve the durability of the mold. In step l, the temperature of the preheated mold is controlled at 200°C±5°C, and the injection rate of the molten metal is controlled at 50 g / s to reduce temperature gradients and thermal stresses.

[0022] Preferably, 0.5 weight percent of nano-alumina is added to the silica sol as a trace amount of nano-filler to improve the mechanical strength and impact resistance of the mold.

[0023] Preferably, after the precision casting, the mold is heated to 600° C. in a thermal regeneration furnace for thermal regeneration treatment to restore some mechanical properties of the mold and extend the service life of the mold.

[0024] Preferably, the thermal cycle furnace in step h is equipped with an automatic temperature gradient control system to achieve a more uniform curing process and reduce internal stress of the mold.

[0025] The present invention provides a rapid prototyping process for silica sol precision casting molds.

[0026] Beneficial effects:

[0027] The silica sol precision casting mold rapid prototyping process, through a series of optimized preparation steps and innovative technical means, significantly solves the problem of small deviations in mold size caused by shrinkage during the sol-gel conversion process in the prior art. By adding sodium dodecylbenzene sulfonate as an organic surfactant in step b, the dispersibility and molding uniformity of the silica sol are improved, thereby reducing uneven shrinkage during the drying process. The use of a dual light source irradiation system including ultraviolet light and visible light, multi-step progressive drying technology combined with ultrasonic vibration treatment not only effectively reduces drying shrinkage, but also improves the density and uniformity of the mold by eliminating tiny bubbles inside the mold, further ensuring the dimensional accuracy and surface quality of the casting.

[0028] The present invention significantly enhances the mechanical strength and impact resistance of the mold by adding nano-alumina as a trace filler to the silica sol, and solves the defects of the silica sol-based mold that is highly brittle and easy to crack or break. The surface is coated with a polydimethylsiloxane reinforcing agent and plasma treated to improve the mold's crack resistance and temperature resistance, and extend the mold's service life. Inert gas atmosphere and preheating steps are used during the heat treatment process to effectively eliminate the residual stress inside the mold, further improving the durability and stability of the mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0030] 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.

[0031] Embodiment 1

[0032] like Figure 1 As shown, an embodiment of the present invention provides a rapid prototyping process for a silica sol precision casting mold, comprising: a. preparing a silicon source, and selecting tetraethoxysilane as a main raw material;

[0033] b. On a magnetic stirrer at a stirring rate of 300 rpm, tetraethoxysilane, deionized water and ethanol were mixed in a volume ratio of 1:4:2, and an appropriate amount of an acidic catalyst was added for hydrolysis reaction. The reaction temperature was controlled at 25 ° C. The duration was 2 hours to generate a silica sol. The amount of the acidic catalyst added was 1% by volume of tetraethoxysilane, and 0.1 weight percent of sodium dodecylbenzene sulfonate was added as an organic surfactant to improve the dispersibility and molding uniformity of the silica sol;

[0034] c. Adjust the pH value of the silica sol to 5.0, and use ammonia or hydrochloric acid for fine-tuning. The pH value in step c is adjusted in the range of 4.8 to 5.2;

[0035] d. Use computer-aided design software to design the three-dimensional model of the required mold;

[0036] e. Use digital light processing rapid prototyping equipment to convert the designed 3D model into a physical mold;

[0037] f. In the DLP device, the exposure time is set to 5 seconds / layer, the layer thickness is 50 microns, and the silica sol is accurately deposited and photocured to form the basic shape of the mold. The deposition rate is controlled at 10 microns / second to ensure the geometric accuracy of the mold. A dual light source irradiation system is used, including ultraviolet light and visible light, to improve the photocuring efficiency and the molding speed of the mold. 0.5 weight percent of nano-alumina is added to the silica sol as a trace nano-filler to improve the mechanical strength and impact resistance of the mold;

[0038] g. Pre-curing the formed silica sol mold in an oven at 60°C for 4 hours to reduce shrinkage during the subsequent drying process;

[0039] h. Place the pre-cured mold in a thermal cycle oven for curing. The curing temperature is controlled at 150°C for 6 hours to transform it into a solid gel structure. The curing process uses ultraviolet radiation to assist curing to accelerate the gelation process and reduce shrinkage. The thermal cycle oven is equipped with an automatic temperature gradient control system to achieve a more uniform curing process and reduce internal stress in the mold.

[0040] i. A multi-step progressive drying technology is adopted, wherein the first step is drying at 40°C for 2 hours, the second step is drying at 60°C for 2 hours, and the third step is drying at 80°C for 2 hours, so as to gradually reduce the humidity and reduce the drying shrinkage. After each step of drying in the multi-step progressive drying technology, the mold needs to be cooled at room temperature for 30 minutes to avoid stress caused by sudden temperature change. The multi-step progressive drying technology further includes ultrasonic vibration treatment after each step of drying to eliminate tiny bubbles inside the mold and improve the compactness and uniformity of the mold. The temperature of the preheated mold is controlled at 200°C ± 5°C, and the injection rate of the molten metal is controlled at 50 g / s to reduce the temperature gradient and thermal stress;

[0041] j. Treat the mold surface after curing and drying, and apply a layer of polydimethylsiloxane reinforcing agent with a coating thickness of 0.5 mm to improve the mechanical strength and crack resistance of the mold. The ratio of the polydimethylsiloxane reinforcing agent is a volume ratio of polydimethylsiloxane to the solvent of 1:10;

[0042] k. Place the surface treated mold in a heat treatment furnace for heat treatment. The heat treatment temperature is set at 700°C for 2 hours to improve the temperature resistance and durability of the mold. During the heat treatment process, the atmosphere in the furnace is an inert gas atmosphere to prevent oxidation of the mold surface. The heat treatment process includes preheating the mold to 300°C before the heat treatment to eliminate the residual stress inside the mold and further improve the durability of the mold.

[0043] l. The treated silica sol mold is applied to the precision casting process, the mold is preheated to 200°C, and then molten metal is injected into the mold. After cooling, a high-precision metal casting is obtained. After the precision casting is completed, the mold is heated to 600°C in a thermal regeneration furnace for thermal regeneration treatment to restore some of the mechanical properties of the mold and extend the service life of the mold.

[0044] Verification Example

[0045] Objective: To verify the feasibility of the invention "a rapid prototyping process for silica sol precision casting molds" and its effectiveness in solving problems such as mold shrinkage and high brittleness.

[0046] Experimental Materials:

[0047] Tetraethoxysilane, purity 99.9%

[0048] Deionized water, conductivity ≤ 0.05μS / cm

[0049] Ethanol, purity 99.8%

[0050] Hydrochloric acid concentration 37%

[0051] Sodium dodecylbenzenesulfonate, purity ≥98%

[0052] Polydimethylsiloxane, viscosity 1000mPa·s

[0053] Nano-alumina (Al 2 O 3 ), particle size about 20 nanometers

[0054] Ammonia water (25% concentration)

[0055] equipment:

[0056] Magnetic stirrer, speed 300rpm

[0057] Digital Light Processing Rapid Prototyping Equipment, Model XYZ-DLP

[0058] Constant temperature oven, temperature control accuracy ±1℃

[0059] Thermal cycle oven with automatic temperature gradient control system

[0060] Heat treatment furnace with inert gas atmosphere control

[0061] Ultrasonic vibration treatment device

[0062] Temperature and humidity sensor and automatic control system

[0063] Plasma treatment equipment

[0064] Thermal regeneration furnace, temperature controlled to 600℃

[0065] Experimental steps:

[0066] a. Prepare silicon source

[0067] Tetraethoxysilane is selected as the main raw material to ensure that its purity is above 99.9%.

[0068] b. Preparation of silica sol

[0069] Tetraethoxysilane, deionized water, and ethanol were mixed in a volume ratio of 1:4:2 on a magnetic stirrer at a stirring rate of 300 rpm.

[0070] Add an appropriate amount of hydrochloric acid with a concentration of 37% to the mixed solution. The amount of acid catalyst added is 1% of the volume of tetraethoxysilane, that is, if 100 mL of TEOS is used, add 1 mL of hydrochloric acid.

[0071] At the same time, 0.1 weight percent of sodium dodecylbenzene sulfonate is added as an organic surfactant to improve the dispersibility and molding uniformity of the silica sol.

[0072] The reaction temperature was controlled at 25°C and stirring was continued for 2 hours to generate a stable silica sol.

[0073] c. pH adjustment

[0074] Use ammonia or hydrochloric acid to adjust the pH of the silica sol to 5.0, ensuring that the pH is adjusted between 4.8 and 5.2.

[0075] d.Mold design

[0076] A 3D model of the required mold was designed using computer-aided design software, and the design included built-in cooling channels to optimize heat management during the casting process.

[0077] e. Rapid prototyping

[0078] Use XYZ-DLP digital light processing rapid prototyping equipment to convert the designed 3D model into a physical mold.

[0079] f. Stereolithography

[0080] In the DLP device, the exposure time was set to 5 seconds / layer and the layer thickness was 50 μm.

[0081] The deposition rate is controlled at 10 μm / s, and a dual light source irradiation system is used, including ultraviolet light and visible light, to improve the photocuring efficiency and the molding speed of the mold.

[0082] Add 0.5 weight percent of nano-alumina (Al 2 O 3 ) as a trace amount of nanofiller to improve the mechanical strength and impact resistance of the mold.

[0083] The silica sol is precisely deposited and light-cured to form the basic shape of the mold.

[0084] g. Pre-curing treatment

[0085] The formed silica sol mold was placed in a constant temperature oven at 60°C for pre-curing for 4 hours to reduce shrinkage during the subsequent drying process.

[0086] h. Curing treatment

[0087] The pre-cured mold was placed in a thermal cycle oven with the curing temperature controlled at 150 °C for 6 hours to transform into a solid gel structure.

[0088] During the curing process, ultraviolet radiation is used to assist the curing to accelerate the gelation process and reduce shrinkage.

[0089] The thermal cycle oven is equipped with an automatic temperature gradient control system to achieve a more uniform curing process and reduce internal stress in the mold.

[0090] i.Multi-step progressive drying

[0091] The following multi-step progressive drying technology is adopted:

[0092] The mold was dried at 40°C for 2 hours, cooled at room temperature for 30 minutes, and subjected to ultrasonic vibration treatment to eliminate minute bubbles inside the mold.

[0093] The film was dried at 60°C for 2 hours, cooled at room temperature for 30 minutes, and subjected to ultrasonic vibration treatment.

[0094] The film was dried at 80°C for 2 hours, cooled at room temperature for 30 minutes, and subjected to ultrasonic vibration treatment.

[0095] By gradually reducing humidity, the shrinkage produced during the drying process is reduced, and the density and uniformity of the mold are improved.

[0096] j.Surface treatment

[0097] A layer of polydimethylsiloxane reinforcing agent is coated on the surface of the cured and dried mold, with a coating thickness of 0.5 mm and a volume ratio of polydimethylsiloxane to solvent of 1:10.

[0098] After coating, plasma treatment is used to enhance the adhesion between polydimethylsiloxane and the mold surface, further improving the mechanical strength and crack resistance of the mold.

[0099] k. Heat treatment

[0100] Place the surface treated mold in a heat treatment furnace for heat treatment:

[0101] Preheat the mold to 300°C to eliminate residual stress inside the mold.

[0102] The heat treatment temperature is set at 700°C and maintained for 2 hours in an inert gas atmosphere to prevent oxidation of the mold surface and improve the temperature resistance and durability of the mold.

[0103] l. Precision casting applications

[0104] Preheat the treated silica sol mold to 200℃±5℃.

[0105] The molten metal is injected into the mold at a rate of 50 g / s to reduce temperature gradients and thermal stresses.

[0106] After cooling, a high-precision metal casting is obtained.

[0107] After the precision casting is completed, the mold is heated to 600℃ in a thermal regeneration furnace for thermal regeneration treatment to restore some of the mechanical properties of the mold and extend the service life of the mold.

[0108] Experimental results:

[0109] Mould size accuracy:

[0110] By comparing 3D scanning with the design model, it was found that the mold size deviation was within ±0.05 mm, which is significantly better than the ±0.1 mm deviation of traditional processes.

[0111] Mechanical strength of mold:

[0112] Using a three-point bending test, it was measured that the bending strength of the mold increased by about 30%, from 50MPa in traditional processes to 65MPa.

[0113] The impact resistance test shows that the mold has no cracks when subjected to 50J impact energy, while traditional molds will crack under 40J impact.

[0114] Heat resistance:

[0115] The mold after heat treatment maintains structural stability at 700°C without obvious deformation or cracks, and its temperature resistance is significantly improved compared with the untreated mold.

[0116] During the precision casting process, the mold can withstand multiple high temperature cycles without performance degradation.

[0117] Service life:

[0118] The molds that have been heat-regenerated can be used about 50% more times in the continuous casting process, from 100 to 150 times.

[0119] Surface quality:

[0120] The casting surface is smooth and the roughness Ra value is reduced by about 20%, meeting the industrial standard requirements.

[0121] Process stability:

[0122] Automatic monitoring and adjustment of temperature and humidity throughout the entire process ensures the consistency and stability of mold forming and reduces human operation errors.

[0123] in conclusion:

[0124] By implementing the above steps, the silica sol precision casting mold rapid prototyping process of the present invention effectively solves the problem of mold size deviation caused by shrinkage during the sol-gel conversion process, and significantly improves the mechanical strength, impact resistance and heat resistance of the mold. The surface treatment and heat treatment steps further enhance the durability and service life of the mold, making it suitable for high-load and complex casting processes. The verification results show that this process has good feasibility and significant technical advantages, meeting the needs of industrial applications.

[0125] Comparative experiment

[0126] Comparative group: The conventional silica sol mold manufacturing process was adopted, and the steps were the same as those of the present invention, except for the following improved steps:

[0127] No sodium dodecylbenzene sulfonate and nano-alumina (Al 2 O 3 ).

[0128] Use a single light source, UV light only, for light curing.

[0129] No ultrasonic vibration treatment or plasma treatment was performed.

[0130] No thermal regeneration is performed.

[0131] Comparison results:

[0132] The mold size deviation reaches ±0.1 mm.

[0133] The mold has a bending strength of 50MPa and low impact resistance, and is prone to cracking under a 40J impact.

[0134] The surface roughness Ra value of the casting is relatively high, reaching the edge of industrial standard requirements.

[0135] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rapid prototyping process for silica sol precision casting mold, characterized in that: include: a. Prepare a silicon source and select tetraethoxysilane as the main raw material; b. On a magnetic stirrer at a stirring rate of 300 rpm, tetraethoxysilane, deionized water and ethanol were mixed in a volume ratio of 1:4:2, and an appropriate amount of an acidic catalyst was added for hydrolysis reaction. The reaction temperature was controlled at 25°C for 2 hours to generate a silica sol; c. Adjust the pH value of silica sol to 5.0 and use ammonia or hydrochloric acid for fine-tuning; d. Use computer-aided design software to design the three-dimensional model of the required mold; e. Use digital light processing rapid prototyping equipment to convert the designed 3D model into a physical mold; f. In the DLP device, set the exposure time to 5 seconds / layer and the layer thickness to 50 microns, accurately deposit and photo-cure the silica sol to form the basic shape of the mold; g. Pre-curing the formed silica sol mold in an oven at 60°C for 4 hours to reduce shrinkage during the subsequent drying process; h. Place the pre-cured mold in a thermal cycle oven for curing at a temperature of 150°C for 6 hours to transform it into a solid gel structure; i. Use multi-step progressive drying technology, the first step is drying at 40℃ for 2 hours, the second step is drying at 60℃ for 2 hours, and the third step is drying at 80℃ for 2 hours, so as to gradually reduce humidity and reduce drying shrinkage; j. Treat the mold surface after curing and drying by coating a layer of polydimethylsiloxane reinforcing agent with a coating thickness of 0.5 mm to improve the mechanical strength and crack resistance of the mold; k. Place the surface treated mold in a heat treatment furnace for heat treatment. The heat treatment temperature is set at 700°C for 2 hours to improve the temperature resistance and durability of the mold. l. Apply the treated silica sol mold to the precision casting process, preheat the mold to 200°C, then inject molten metal into the mold, and obtain high-precision metal castings after cooling.

2. A silica sol precision casting mold rapid prototyping process according to claim 1, characterized in that: The amount of the acidic catalyst added in step b is 1% of the volume of tetraethoxysilane, 0.1 weight percent of sodium dodecylbenzene sulfonate is added in step b as an organic surfactant to improve the dispersibility and molding uniformity of the silica sol, and the pH value in step c is adjusted in the range of 4.8 to 5.

2.

3. A silica sol precision casting mold rapid prototyping process according to claim 1, characterized in that: In the step f, the deposition rate is controlled at 10 μm / s to ensure the geometric accuracy of the mold. In the step f, a dual light source irradiation system is used, including ultraviolet light and visible light, to improve the photocuring efficiency and the molding speed of the mold. The pre-curing treatment in the step g is carried out in a constant temperature oven, and the humidity of the oven is controlled at 20% RH. The curing treatment in the step h uses ultraviolet radiation to assist curing to accelerate the gelation process and reduce the shrinkage.

4. The rapid prototyping process of silica sol precision casting mold according to claim 1, characterized in that: The multi-step progressive drying technology in step i requires the mold to be cooled at room temperature for 30 minutes after each drying step to avoid stress caused by sudden temperature change. The multi-step progressive drying technology in step i further includes performing ultrasonic vibration treatment after each drying step to eliminate tiny bubbles inside the mold and improve the density and uniformity of the mold. The ratio of the polydimethylsiloxane enhancer in step j is a volume ratio of polydimethylsiloxane to solvent of 1:

10.

5. The rapid prototyping process of silica sol precision casting mold according to claim 1, characterized in that: During the heat treatment process in step k, the atmosphere in the furnace is an inert gas atmosphere to prevent oxidation of the mold surface. The heat treatment process in step k includes preheating the mold to 300°C before heat treatment to eliminate residual stress inside the mold and further improve the durability of the mold. In step l, the temperature of the preheated mold is controlled at 200°C±5°C, and the injection rate of the molten metal is controlled at 50 g / s to reduce temperature gradients and thermal stress.

6. The rapid prototyping process of silica sol precision casting mold according to claim 1, characterized in that: 0.5 weight percent of nano-alumina is added to the silica sol as a trace amount of nano-filler to improve the mechanical strength and impact resistance of the mold.

7. The rapid prototyping process of silica sol precision casting mold according to claim 1, characterized in that: After the precision casting, the mold is heated to 600° C. in a thermal regeneration furnace for thermal regeneration treatment to restore some mechanical properties of the mold and extend the service life of the mold.

8. The rapid prototyping process of silica sol precision casting mold according to claim 1, characterized in that: The thermal cycle oven in step h is equipped with an automatic temperature gradient control system to achieve a more uniform curing process and reduce internal stress of the mold.

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