Process for improving cleanliness of silica sol investment casting shell

Abstract

According to the technology for improving the cleanliness of the silica sol investment casting shell, after primary steam dewaxing, the shell is turned over, hot water is poured into the shell, then secondary steam treatment and rapid pressure relief spraying are conducted, and residual wax and impurities in the shell are thoroughly removed. The process remarkably improves the cleanliness of the casting, avoids the defects of sand holes and black spots, and is suitable for various silica sol investment casting scenes.

Description

Technical Field

[0001] The invention relates to the technical field of casting, and in particular to a process for improving the cleanliness of a silica sol investment casting shell. Background Art

[0002] In silica sol investment casting, the traditional dewaxing process involves placing the mold shell upside down (with the pouring cup facing downward) in a dewaxing kettle and subjecting it to high-temperature steam (150-170°C, 0.6-0.8 MPa) for 10-20 minutes to remove the wax. However, this process has drawbacks: wax in the mold shell's interior corners (especially blind spots) is difficult to completely remove, and the remaining wax may contain impurities such as ash and sand powder.

[0003] Residual impurities remain in the mold shell after firing, forming defects such as sand holes and black spots during pouring, affecting casting quality. Existing processes do not offer an effective solution for residual wax in dead corners, relying solely on a single dewaxing process, resulting in insufficient cleanliness. Summary of the Invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a process for improving the cleanliness of silica sol investment casting shells.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a process for improving the cleanliness of silica sol investment casting shells, wherein the specific steps of the process are as follows: S1: Initial dewaxing: Turn the mold upside down with the pouring cup facing downwards, place it in a dewaxing kettle, and introduce hot steam at 150-170°C and 0.6-0.8 MPa for 10-20 minutes; S2: Secondary dewaxing: Turn the mold shell over with the pouring cup facing upwards, fill the mold shell with 60-100℃ hot water, then push it back into the dewaxing kettle and pass hot steam at 150-170℃ and 0.6-0.8MPa for 5-10 minutes; S3: Pressure relief spray: Quickly release the pressure in the kettle so that the hot water in the mold shell will gush out under the action of negative pressure, removing residual wax and impurities.

[0006] Preferably, in step S1, the steam temperature of the initial dewaxing is 160° C., and the treatment time is 15 minutes.

[0007] Preferably, in step S2, the temperature of the hot water for the secondary dewaxing is 80-90°C.

[0008] Preferably, in step S3, the pressure in the kettle drops to normal pressure within 3 to 5 seconds during the pressure relief spraying.

[0009] Preferably, in step S3, after spraying, high-efficiency nozzles are used to spray the shell in multiple directions.

[0010] Compared with the existing technology, the present invention has the following advantages: The present invention optimizes the primary dewaxing process: In step S1, the primary dewaxing treatment is performed using hot steam at 150-170°C. The selected temperature and pressure ensure that the hot steam quickly penetrates the mold surface, fully softening and dissolving the wax layer within the shell, avoiding the problem of wax residue caused by uneven heating. Furthermore, the process takes 15 minutes to completely remove most residual wax and impurities, laying a good foundation for the subsequent secondary dewaxing.

[0011] Secondly, the secondary dewaxing process enhances the cleaning effect: In step S2, the secondary dewaxing process is treated with hot water at 60-100°C and then reintroduced into the dewaxing kettle, where steam heating further dissolves and removes the remaining wax layer. Controlling the temperature and amount of hot water during this stage helps increase the dissolution rate of the wax layer, prevents the wax layer from solidifying, and improves the cleaning effect of the secondary dewaxing process, thereby enhancing the surface finish and precision of the final casting.

[0012] Finally, in the design of step S3 of the efficient pressure-relief spray process, the pressure within the kettle is quickly released, causing the hot water within the mold shell to gush out under the action of negative pressure, leveraging this force to help remove residual wax and impurities. This process effectively avoids the incomplete cleaning problem associated with traditional dewaxing methods, which is caused by insufficient or uneven pressure. Furthermore, the use of a high-efficiency, multi-directional spray nozzle ensures uniform force across all parts of the mold shell, removing difficult-to-remove residual wax and other impurities, significantly improving cleaning efficiency.

[0013] By meticulously controlling and improving the dewaxing process, this invention effectively avoids the problems of residual wax and impurities remaining in the mold shell during conventional processes. This results in smoother casting surfaces and more precise dimensions, reducing the need for subsequent processing and finishing. Furthermore, due to the more efficient dewaxing and spraying processes, the overall production cycle is shortened, improving production efficiency.

[0014] The hot steam and hot water treatment method used in this process not only improves cleaning results, but also reduces the use of chemical cleaning agents to a certain extent, meeting environmental protection requirements. At the same time, the optimized control of temperature and pressure improves energy efficiency and reduces energy consumption, achieving excellent energy-saving effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0016] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the present invention is described in detail below with reference to the embodiments.

[0017] Please refer to Figure 1 The present invention provides a process for improving the cleanliness of silica sol investment casting shells: the specific steps of the method are as follows: S1: Initial dewaxing: Turn the mold shell upside down with the pouring cup facing downward, place it in the dewaxing kettle, and pass hot steam at 150~170℃ and 0.6~0.8MPa for 10~20 minutes.

[0018] The high temperature and pressure of the steam effectively raises the temperature of the wax pattern, thereby reducing the viscosity of the wax and making it easier to remove from the shell. The inverted shell design ensures that the wax pattern flows out naturally due to gravity, avoiding uneven or incomplete dewaxing caused by wax accumulation.

[0019] By turning the mold upside down with the pouring cup facing downward, the wax pattern can be discharged evenly, thus avoiding excessive local pressure on the mold shell caused by excessive accumulation of wax pattern, and thus preventing the mold shell from breaking or deforming due to uneven pressure.

[0020] By using steam at high temperature and appropriate pressure, the wax pattern can be heated more quickly and forced to separate from the shell, shortening the dewaxing time and thus improving production efficiency.

[0021] The high temperature of the steam evenly heats the entire mold, helping the wax pattern to reach the ideal state of removal in a short time. The steam can penetrate every tiny part of the mold, helping to remove the wax pattern more thoroughly, especially in some complex castings.

[0022] If the wax pattern is not fully discharged or is discharged too slowly, the shell may crack due to thermal stress or excessive local temperature difference. Rapid heating with high-temperature steam can effectively avoid this situation.

[0023] S2: Secondary dewaxing: Turn the mold shell over with the pouring cup facing upwards, fill the mold shell with 60~100℃ hot water, then push it back into the dewaxing kettle and pass hot steam at 150~170℃ and 0.6~0.8MPa for 5~10 minutes.

[0024] By turning the mold shell over with the pouring cup facing upward, hot water and steam can be evenly distributed into the mold shell, promoting the complete dissolution of the wax pattern, reducing residual wax, and thus improving dewaxing efficiency.

[0025] Using hot water and hot steam to treat the mold shell can make the mold shell gradually adapt to the changes in heat, avoid cracks or damage caused by excessive temperature differences, and ensure the integrity of the mold shell.

[0026] The preheating of hot water and the high-temperature treatment of hot steam can act more evenly on the wax model, ensuring the uniform dissolution of the wax model and reducing local residue.

[0027] By thoroughly dewaxing, the influence of the wax pattern on the surface of the final casting can be reduced, irregularities or defects on the casting surface can be avoided, and the surface quality of the casting can be improved.

[0028] The combined effect of hot water and hot steam can effectively shorten the dewaxing time, making the entire casting process more efficient and improving production efficiency.

[0029] Compared with traditional chemical dewaxing methods, this physical dewaxing method of hot water and hot steam avoids the use of harmful chemicals, reduces environmental pollution and potential harm to the health of operators.

[0030] S3: Pressure relief spray: Quickly release the pressure in the kettle so that the hot water in the mold shell will gush out under the action of negative pressure, removing residual wax and impurities.

[0031] By quickly unloading the pressure, the hot water in the mold shell will gush out under the action of negative pressure, which can effectively discharge the residual wax pattern in the mold shell quickly, prevent the wax pattern from accumulating in the mold shell, ensure thorough dewaxing, and reduce wax residue.

[0032] Under the action of negative pressure, hot water can quickly impact the inner surface of the shell, remove the wax mold residue and other impurities, avoid the impurities from affecting the quality of the casting in the subsequent casting process, and ensure the accuracy and surface quality of the casting.

[0033] This rapid pressure relief method can significantly shorten the dewaxing time, improve the dewaxing efficiency, reduce time waste in the process flow, and thus improve production efficiency.

[0034] In the traditional dewaxing process, the wax pattern may solidify inside the mold shell due to cooling. Using negative pressure spray can prevent the wax pattern from solidifying, reduce the difficulty of subsequent cleaning, and ensure more thorough dewaxing.

[0035] Through negative pressure spraying, hot water can evenly flush every corner of the mold shell, thereby avoiding damage to the mold shell caused by local uneven pressure, enhancing the structural stability of the mold shell, and ensuring the smooth progress of subsequent casting.

[0036] Compared with traditional chemical dewaxing methods, the physical method of using hot water and negative pressure spraying can effectively reduce the use of harmful chemicals, reduce pollution to the environment, and also reduce the health risks of operators.

[0037] Preferably, in step S1, the steam temperature of the initial dewaxing is 160° C., and the treatment time is 15 minutes.

[0038] Preferably, in step S2, the temperature of the hot water for the secondary dewaxing is 80-90°C.

[0039] Preferably, in step S3, the pressure in the kettle drops to normal pressure within 3 to 5 seconds during the pressure relief spraying.

[0040] Preferably, in step S3, after spraying, high-efficiency nozzles are used to spray the shell in multiple directions.

[0041] The present invention has been described with reference to the above embodiments. However, the above embodiments are merely exemplary embodiments of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and improvements that do not depart from the spirit and scope of the present invention are intended to be protected by the present invention.

Claims

1. A process for improving the cleanliness of silica sol investment casting shells, characterized by: The specific steps of the process are as follows: S1: Initial dewaxing: Turn the mold upside down with the pouring cup facing downwards, place it in a dewaxing kettle, and introduce hot steam at 150-170°C and 0.6-0.8 MPa for 10-20 minutes; S2: Secondary dewaxing: Turn the mold shell over with the pouring cup facing upwards, fill the mold shell with 60-100℃ hot water, then push it back into the dewaxing kettle and pass hot steam at 150-170℃ and 0.6-0.8MPa for 5-10 minutes; S3: Pressure relief spray: Quickly release the pressure in the kettle so that the hot water in the shell will gush out under the action of negative pressure, removing residual wax and impurities.

2. A process for improving the cleanliness of silica sol investment casting shells according to claim 1, characterized in that: In step S1, the steam temperature of the initial dewaxing is 160° C., and the treatment time is 15 minutes.

3. A process for improving the cleanliness of silica sol investment casting shells according to claim 1, characterized in that: In step S2, the temperature of the hot water for the secondary dewaxing is 80-90°C.

4. A process for improving the cleanliness of silica sol investment casting shells according to claim 1, characterized in that: In step S3, during the pressure relief spraying, the pressure in the kettle drops to normal pressure within 3 to 5 seconds.

5. The process for improving the cleanliness of silica sol investment casting shells according to claim 1, wherein: In step S3, after spraying, high-efficiency nozzles are used to spray the shell in multiple directions.

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