Silica sol and gypsum composite shell and manufacturing method and application thereof
By using gypsum to fill the deep hole and deep groove parts in the silicon sol shell casting process, combining the surface layer and reinforcement layer of the silicon sol shell, the problems of insufficient strength of the shell and difficulty in removing debris are solved, and efficient and stable Casting production.
Patent Information
- Application Number
- CN202411575572.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-06
- Publication Date
- 2025-02-14
AI Technical Summary
Silicon sol shell casting process When casting alloy casting with deep hole and deep groove structures, there are problems such as insufficient strength of the shell, poor breathability, difficulty in dewaxing, and difficult debris in deep hole and deep grooves, which affect the appearance quality and use of the castings. performance.
Using the manufacturing method of silicon sol and gypsum composite shell, the overall strength and production of the shell are improved by filling the gypsum slurry in the deep hole and deep groove parts of the wax mold module, and combining the surface layer and reinforcement layer of the silicon sol shell. efficiency.
It improves the overall strength of the molded shell, simplifies the manufacturing process, ensures the surface quality and dimensional accuracy of the castings, reduces production costs and labor strength, and improves the qualification rate of the castings.
Smart Images
Figure CN119426523A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of investment casting, and in particular relates to a silica sol and gypsum composite shell and a manufacturing method and application thereof. Background Art
[0002] Silica sol shell casting process is a precision casting method, which mainly includes making molds, preparing wax patterns, making shells, drying and hardening, melting lost wax patterns, pouring metal, cleaning and post-processing. Silica sol shell casting process has the advantages of high dimensional accuracy, wide application range, high production efficiency and environmental friendliness, and has been widely used in the field of precision casting.
[0003] However, the silica sol shell casting process also has some limitations, especially when applied to alloy castings with deep hole and deep groove structures (including heat dissipation ribs, special-shaped holes, complex cavities, etc.). There are problems such as insufficient shell strength, poor air permeability, difficulty in dewaxing, and difficulty in removing debris in deep holes and deep grooves. These problems will affect the appearance quality of the castings and may also pose a potential threat to the subsequent performance of the castings. For example, in some parts that require high precision and high cleanliness, residual debris may cause performance degradation or failure of the parts.
[0004] Therefore, those skilled in the art urgently need to propose a silica sol and gypsum composite shell and a manufacturing method and application thereof, so as to be suitable for the casting of alloy castings with deep hole and deep groove structure. Summary of the invention
[0005] The purpose of the present invention is to solve the above-mentioned technical problems. A silica sol and gypsum composite mold shell and its manufacturing method and application are proposed. The silica sol mold shell and the gypsum mold shell are used in combination to make up for the technical defects of a single silica sol mold shell and a single gypsum mold shell, improve the overall strength of the mold shell with a deep hole and deep groove structure while reducing the manufacturing difficulty of the mold shell, and ensure the consistency of the shrinkage rate of the mold shell with aluminum alloy and magnesium alloy castings, which is convenient for subsequent steam dewaxing, high-temperature roasting and mold shell cleaning.
[0006] Based on the first aspect of the present invention, the technical solution proposed in this application is:
[0007] A method for manufacturing a composite shell of silica sol and gypsum comprises the following steps:
[0008] The wax mold module with deep hole and deep groove structure is sequentially coated with surface coating, sprinkled with surface sand, coated with transition coating, sprinkled with transition sand, filled with gypsum slurry at the deep hole and deep groove of the wax mold module, coated with reinforcement coating, sprinkled with reinforcement sand and sealed with slurry, and then dewaxed and calcined to obtain a silica sol and gypsum composite shell;
[0009] The surface coating comprises silica sol, mullite powder, a wetting agent and a defoaming agent, wherein, relative to 10 kg of silica sol, the content of mullite powder is 17-20 kg, the content of the wetting agent is 16 ml, the content of the defoaming agent is 12 ml, and the viscosity of the surface coating is 35-40 s; the wetting agent and the defoaming agent can be conventional materials in the art, such as the wetting agent is fatty alcohol polyoxyethylene ether, and the defoaming agent is n-octanol.
[0010] The transition layer coating comprises silica sol and mullite powder, wherein the content of mullite powder is 16-17 kg relative to 10 kg of silica sol, and the viscosity of the transition layer coating is 20-25 s;
[0011] The reinforcing layer coating comprises silica sol and mullite powder, wherein the content of mullite powder is 14-15 kg relative to 10 kg of silica sol, and the viscosity of the reinforcing layer coating is 25-30 s;
[0012] The coating used for sealing is a reinforcing layer coating;
[0013] The gypsum slurry is made of α gypsum powder and water, wherein the mass ratio of α gypsum powder to water is 100:
[0014] (30~35).
[0015] Preferably, the particle size of the surface layer sand is 60-80 mesh, the particle size of the transition layer sand is 30-60 mesh, the particle size of the reinforcement layer sand is 16-30 mesh, and the surface layer sand, transition layer sand and reinforcement layer sand are all made of mullite sand, the particle size of the mullite powder in the surface layer coating is 325 mesh, and the particle size of the mullite powder in the transition layer coating and the reinforcement layer coating are both 270-325 mesh.
[0016] Preferably, after the gypsum slurry has filled the deep holes and deep grooves of the wax mold module, a "U"-shaped iron wire is inserted and part of the iron wire is exposed while it is in a paste state before it is completely solidified. The part of the iron wire buried in the gypsum slurry is used to reinforce the strength of the gypsum, and the exposed part of the iron wire is used to connect the gypsum slurry with the subsequent reinforcement layer coating after it is cured, thereby improving the overall strength of the mold shell.
[0017] Preferably, the silica sol has a density of 1.20-1.21 g / cm3, a pH value of 9-10, a kinematic viscosity of ≤8 mm2 / s, a particle diameter of 9-20 nm, a SiO2 content of 29-31% by weight, and a Na2O content of ≤0.5%.
[0018] Preferably, the hardening temperatures of the surface layer coating, transition layer coating and reinforcement layer coating are all 24±2°C, wherein the surface layer coating is applied with one layer, the drying time under windless conditions is ≥6h, and the ambient humidity is 50-60%; the transition layer coating is applied with one layer, the drying time under windless or light breeze conditions is ≥8h, and the ambient humidity is 40-60%; the reinforcement layer coating is applied with four layers, the drying time of the reinforcement layer coating under strong wind conditions is ≥8h, and the ambient humidity is 40-60%, so as to ensure the quality and strength of the shell.
[0019] Preferably, after the gypsum slurry is poured into the deep hole and deep groove structure of the wax mold module, it is cured for 0.5 to 1 hour and then the reinforcing layer coating is applied, thereby significantly shortening the manufacturing time of the mold shell.
[0020] Preferably, the dewaxing method is steam dewaxing, the dewaxing pressure is 0.5-0.6Mpa, the dewaxing time is 6-8min, and the placement time is 0.5-1h. The roasting temperature is 950-1100°C, and the heat preservation is 1-2h after roasting. After the silica sol shell and the gypsum shell are composited, they can meet the requirements of steam dewaxing, high temperature roasting, and aluminum alloy pouring temperature, so the material properties meet the process requirements.
[0021] Based on the second aspect of the present invention, the present application proposes a silica sol and gypsum composite shell, which is manufactured by the above-mentioned silica sol and gypsum composite shell manufacturing method.
[0022] Based on the third aspect of the present invention, the present application proposes the use of the above-mentioned silica sol and gypsum composite shell in the preparation of aluminum alloy castings with deep holes and deep grooves and deep holes and deep grooves magnesium alloy castings.
[0023] The present invention also includes other steps that enable a silica sol and gypsum composite shell and its manufacturing method and application to be used normally, which are all conventional means in the art. In addition, steps not limited in the present invention all adopt the existing technology in the art.
[0024] The working principle of the present invention is that aluminum alloy and magnesium alloy castings with deep holes and deep structures are produced by a silica sol investment casting process. After the transition layer of the coating process in the deep holes and deep grooves is completed, the space in the deep holes and deep grooves is narrow. As the mesh number of the back layer mullite becomes smaller (the particle size becomes larger), it is not easy for sand to fill the deep holes and deep grooves, or sand accumulates at the mouth, thereby forming internal voids, resulting in low strength, which can easily cause local leakage during the pouring process of the aluminum alloy or magnesium alloy liquid metal and lead to scrap.
[0025] Therefore, the present invention uses silica sol as a binder, mullite powder and mullite sand of different specifications as refractory materials, and after manufacturing the shell of the surface layer and the transition layer through a specific process, another casting process is used, that is, the commonly used α gypsum powder is mixed with water in proportion to form a paste, and filled into the deep hole and deep groove. After 0.5 to 1 hour of gypsum solidification, the subsequent shell making operation is simplified and the shell making efficiency is improved. At the same time, since the coating and α gypsum of the silica sol shell have good heat resistance and similar shrinkage rate, the surface quality and dimensional accuracy of the casting can be effectively guaranteed. By utilizing the shorter solidification time of the gypsum slurry, the shell making time is effectively shortened, while the production efficiency is improved, and the consistency of the process and the stability and reliability of the quality are guaranteed.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] 1. The silica sol, mullite refractory material, α-gypsum powder, etc. used in this application are conventional casting raw materials with low cost and easy to obtain.
[0028] 2. This application targets deep holes and deep grooves in castings. Based on the use of a silica sol shell process for the surface layer and transition layer of the wax mold module, a gypsum filling process is then used in the deep holes and deep grooves. The operation is simple, which shortens the shell production cycle and effectively improves production efficiency.
[0029] 3. The operating process of this application is stable, and the castings finally produced can maintain consistent surface finish and dimensional accuracy.
[0030] 4. The material of the mold shell of the present application has sufficient refractoriness, and the gypsum material has good disintegration performance, which effectively improves the efficiency of subsequent mold shell cleaning and helps to reduce labor intensity.
[0031] 5. Since the deep holes and deep grooves of the mold shell are filled with gypsum in the present application, it is helpful to ensure the integrity of the mold shell in the subsequent pouring process, thereby improving the qualified rate of the castings.
[0032] 6. This application is not only applicable to the production of aluminum alloy castings and magnesium alloy castings, but also has good promotion potential.
[0033] In summary, the process of the present invention is simple and easy to manufacture. The materials used are cheap and easily available, which helps to save production costs and can ensure the casting quality of aluminum alloy castings and magnesium alloy castings with deep hole and deep groove structures. It is also easy to operate, labor-saving and fast, greatly shortening the shell making time and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a schematic diagram of the overall structure of the wax mold module in the embodiment.
[0035] Figure 2 It is a schematic diagram of the overall structure of the medium shell after the surface layer and transition layer are completed and the gypsum is filled in the embodiment.
[0036] Figure 3 It is a schematic diagram of the overall structure of the medium shell after the reinforcement layer is coated in the embodiment. DETAILED DESCRIPTION
[0037] The technology of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0038] Example
[0039] like Figures 1 to 3 As shown, this embodiment proposes a method for manufacturing a silica sol and gypsum composite shell, comprising the following steps:
[0040] The wax mold module with deep hole and deep groove structure is sequentially coated with surface coating, sprinkled with surface sand, coated with transition coating, sprinkled with transition sand, filled with gypsum slurry at the deep hole and deep groove of the wax mold module, coated with reinforcement coating, sprinkled with reinforcement sand and sealed with slurry, and then dewaxed and calcined to obtain a silica sol and gypsum composite shell;
[0041] The surface coating comprises silica sol, mullite powder, a wetting agent and a defoaming agent, the transition layer coating and the reinforcing layer coating both comprise silica sol and mullite powder, the surface layer sand, the transition layer sand and the reinforcing layer sand are all mullite sand, and the coating used for sealing is the reinforcing layer coating; the gypsum slurry is made of α gypsum powder and water, wherein the mass ratio of α gypsum powder to water is 100:(30-35).
[0042] The silica sol has a density of 1.20-1.21 g / cm3, a pH value of 9-10, a kinematic viscosity of ≤8 mm2 / s, a colloidal particle diameter of 9-20 nm, a SiO2 content of 29-31% by weight, and a Na2O content of ≤0.5%.
[0043] The proportions of the surface coating, transition layer and reinforcement layer coating are implemented with reference to Table 1:
[0044] Table 1 Ratio of each coating of silica sol shell
[0045]
[0046] In addition, the preparation process parameters of the silica sol and gypsum composite shell are implemented with reference to Table 2:
[0047] Table 2 Shell materials and their manufacturing process
[0048]
[0049] In the present embodiment, when the deep holes and deep grooves of the wax mold module are relatively large in size, after the gypsum slurry has completed filling the deep holes and deep grooves and is in a paste state before completely solidifying, a "U"-shaped iron wire is inserted and part of the iron wire is exposed. The part of the iron wire buried in the gypsum slurry is used to reinforce the strength of the gypsum, and the exposed part of the iron wire is used to connect the gypsum slurry with the subsequent reinforcement layer coating after solidification, thereby improving the overall strength of the mold shell.
[0050] Specifically, after the gypsum slurry is poured into the deep hole and deep groove structure of the wax mold module, it is cured for 0.5 to 1 hour and then a reinforcing layer of paint is applied, thereby significantly shortening the manufacturing time of the shell.
[0051] In this embodiment, the dewaxing method is steam dewaxing, the dewaxing pressure is 0.5-0.6Mpa, the dewaxing time is 6-8min, and the placement time is 0.5-1h. The roasting temperature is 950-1100°C, and the heat preservation is 1-2h after roasting. After the silica sol shell and the gypsum shell are composited, they can meet the requirements of steam dewaxing, high temperature roasting, and aluminum alloy pouring temperature, so the material properties meet the process requirements.
[0052] Following the above embodiment, the above-mentioned method for manufacturing a silica sol and gypsum composite shell is used to prepare a silica sol and gypsum composite shell.
[0053] Following the above embodiment, the above silica sol and gypsum composite shell is applied to the preparation of deep hole and deep groove aluminum alloy castings and deep hole and deep groove magnesium alloy castings.
[0054] The working principle of the present invention is that aluminum alloy and magnesium alloy castings with deep holes and deep structures are produced by a silica sol investment casting process. After the transition layer of the coating process in the deep holes and deep grooves is completed, the space in the deep holes and deep grooves is narrow. As the mesh number of the back layer mullite becomes smaller (the particle size becomes larger), it is not easy for sand to fill the deep holes and deep grooves, or sand accumulates at the mouth, thereby forming internal voids, resulting in low strength, which can easily cause local leakage during the pouring process of the aluminum alloy or magnesium alloy liquid metal and lead to scrap.
[0055] Therefore, the present invention uses silica sol as a binder, mullite powder and mullite sand of different specifications as refractory materials, and after manufacturing the shell of the surface layer and the transition layer through a specific process, another casting process is used, that is, the commonly used α gypsum powder is mixed with water in proportion to form a paste, and filled into the deep hole and deep groove. After 0.5 to 1 hour of gypsum solidification, the subsequent shell making operation is simplified and the shell making efficiency is improved. At the same time, since the coating and α gypsum of the silica sol shell have good heat resistance and similar shrinkage rate, the surface quality and dimensional accuracy of the casting can be effectively guaranteed. By utilizing the shorter solidification time of the gypsum slurry, the shell making time is effectively shortened, while the production efficiency is improved, and the consistency of the process and the stability and reliability of the quality are guaranteed.
[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for manufacturing a composite shell of silica sol and gypsum, characterized in that: The steps include: The wax mold module with deep hole and deep groove structure is sequentially coated with surface coating, sprinkled with surface sand, coated with transition coating, sprinkled with transition sand, filled with gypsum slurry at the deep hole and deep groove of the wax mold module, coated with reinforcement coating, sprinkled with reinforcement sand and sealed with slurry, and then dewaxed and calcined to obtain a silica sol and gypsum composite shell; The surface coating comprises silica sol, mullite powder, a wetting agent and a defoaming agent, wherein, relative to 10 kg of silica sol, the content of mullite powder is 17-20 kg, the content of the wetting agent is 16 ml, the content of the defoaming agent is 12 ml, and the viscosity of the surface coating is 35-40 s; The transition layer coating comprises silica sol and mullite powder, wherein the content of mullite powder is 16-17 kg relative to 10 kg of silica sol, and the viscosity of the transition layer coating is 20-25 s; The reinforcing layer coating comprises silica sol and mullite powder, wherein the content of mullite powder is 14-15 kg relative to 10 kg of silica sol, and the viscosity of the reinforcing layer coating is 25-30 s; The coating used for sealing is a reinforcing layer coating; The gypsum slurry is prepared by adding alpha gypsum powder and water, wherein the mass ratio of the alpha gypsum powder to water is 100:(30-35).
2. The method for manufacturing a silica sol and gypsum composite shell according to claim 1, characterized in that: The particle size of the surface layer sand is 60-80 meshes, the particle size of the transition layer sand is 30-60 meshes, and the particle size of the reinforcement layer sand is 16-30 meshes. The surface layer sand, transition layer sand and reinforcement layer sand are all made of mullite sand. The particle size of the mullite powder in the surface layer coating is 325 meshes, and the particle sizes of the mullite powder in the transition layer coating and the reinforcement layer coating are both 270-325 meshes.
3. The method for manufacturing a silica sol and gypsum composite shell according to claim 2, characterized in that: After the gypsum slurry has filled the deep holes and deep grooves of the wax mold module, it is in a paste state before it is completely solidified. A "U"-shaped iron wire is inserted and part of the iron wire is exposed. The part of the iron wire buried in the gypsum slurry is used to reinforce the strength of the gypsum, and the exposed part of the iron wire is used to connect the gypsum slurry with the subsequent reinforcement layer coating after it is solidified.
4. The method for manufacturing a silica sol and gypsum composite shell according to claim 3, characterized in that: The density of the silica sol is 1.20-1.21 g / cm 3 , pH value is 9-10, kinematic viscosity ≤8mm 2 / s, the diameter of the colloid particles is 9-20nm, the content of SiO2 is 29-31% by weight, and the content of Na2O is ≤0.5%.
5. The method for manufacturing a silica sol and gypsum composite shell according to claim 4, characterized in that: The hardening temperatures of the surface layer coating, transition layer coating and reinforcement layer coating are all 24±2°C, among which, the surface layer coating is applied with one layer, the drying time under windless conditions is ≥6h, and the ambient humidity is 50-60%; the transition layer coating is applied with one layer, the drying time under windless or light breeze conditions is ≥8h, and the ambient humidity is 40-60%; the reinforcement layer coating is applied with four layers, the drying time of the reinforcement layer coating under strong wind conditions is ≥8h, and the ambient humidity is 40-60%.
6. The method for manufacturing a silica sol and gypsum composite shell according to claim 5, characterized in that: After pouring gypsum slurry into the deep hole and deep groove structure of the wax mold module, solidify it for 0.5 to 1 hour, and then apply the reinforcement layer coating.
7. The method for manufacturing a silica sol and gypsum composite shell according to claim 1, characterized in that: The dewaxing method is steam dewaxing, the dewaxing pressure is 0.5-0.6Mpa, the dewaxing time is 6-8min, and the placement time is 0.5-1h.
8. The method for manufacturing a silica sol and gypsum composite shell according to claim 1, characterized in that: The calcination temperature is 950-1100° C. and the temperature is kept for 1-2 hours after calcination.
9. A silica sol and gypsum composite shell, characterized in that: The composite shell is prepared by the method for manufacturing a silica sol and gypsum composite shell as described in any one of claims 1 to 8.
10. Use of the silica sol and gypsum composite shell according to claim 9 in the preparation of aluminum alloy castings and magnesium alloy castings with deep hole and deep groove structures.