Method of filling a closed cavity with buoyant material

Abstract

The application provides a method for pouring and filling buoyancy material in a closed cavity, which comprises the following steps: step one, processing and installation of the pouring and filling device: machining the closed cavity to obtain at least two round holes, arranging a connecting pipe at the round hole, and connecting the connecting pipe with a vacuum / pressurization system; step two, pre-filling of a solid buoyancy material block; step three, preparation of glue solution; step four, keeping the pressure in the closed cavity as negative pressure under the action of the vacuum / pressurization system, and injecting the glue solution; and step five, pressurizing the closed cavity when the glue solution is not solidified, and keeping the first pressure value P1 until the glue solution is solidified. The method for pouring and filling buoyancy material in the closed cavity can effectively realize pouring and filling of the buoyancy material into the closed cavity, improve the filling efficiency of the buoyancy material, reduce the material cost of the buoyancy material, simplify the filling process, enhance the strength and compactness of the buoyancy material structure, and avoid the generation of gaps between the closed cavity and the buoyancy material.

Description

Technical Field

[0001] This invention relates to the field of buoyancy material casting and filling technology, and more specifically, to a method for casting and filling buoyancy material in a closed cavity. Background Technology

[0002] Current solid buoyancy materials are closed-cell composite foams made by uniformly dispersing fillers such as hollow glass microspheres or resin microspheres into a polymer matrix and then processing them through a specific process. Most of these buoyancy materials are composites of epoxy resin and hollow glass microspheres. This type of solid buoyancy material has excellent properties such as high strength, low density, and low water absorption, and can provide buoyancy for underwater equipment, ensuring the effective load of the underwater equipment. It can be widely used as a good filler material in deep-sea equipment.

[0003] However, existing deep-sea buoyancy components are mainly made of epoxy-based / hollow glass microsphere composite solid buoyancy materials. Under the pressure of deep seawater, the shrinkage deformation of the buoyancy components is much greater than that of the main structure of the submersible. If the installation and filling design of the buoyancy components are unreasonable, or if there are gaps between the buoyancy materials after filling, the buoyancy components may loosen under the pressure of deep water, or even crack due to excessive stress caused by filling or installation. Usually, the main structure of the underwater equipment can be directly connected to the buoyancy material, that is, the buoyancy material can be connected to the metal frame using double-ended screws, or the buoyancy material can be cut into prefabricated blocks and filled into the metal frame of the underwater equipment and fixed with adhesive. However, for cavity structures, buoyancy materials cannot be installed internally using screws or adhesives, and cannot be installed by means of... Traditional filling processes are used for skeleton filling; Patent application number 201710042142.8 discloses a solid buoyancy material casting system and its process, including control modules for buoyancy material curing temperature, pressure and vacuum degree, etc. This patent only proposes a solid buoyancy material preparation system; Patent application number 202111193591.5 discloses a method for preparing buoyancy material using an integral molding process, which uses staged filling to solve the problem of large heat release during the curing process under room temperature curing conditions. This patent proposes to control the heat release problem in the staged curing process, but it does not effectively solve the problem of how to fill buoyancy material inside the cavity structure. Therefore, it is of great significance to study how to fill buoyancy material in a closed cavity, thereby avoiding the loosening or cracking of buoyancy components in submersibles under high water pressure at great depths.

[0004] Patent CN113402851A mentions an underwater irregularly shaped component and its preparation method. This method involves uniformly bonding hollow spheres to the inner surface of an irregularly shaped shell, then covering it with microspheres. Microspheres are then evenly dispersed in the gaps between the hollow spheres using mechanical vibration. Next, resin injection material is injected into the irregularly shaped shell filled with the composite hollow spheres and microspheres. The injected irregularly shaped shell is then heated and cured under vacuum. Post-processing of the cured irregularly shaped shell yields the prepared underwater irregularly shaped component. The method mentions injecting the slurry directly under pressure or using a guide net. This method can improve the mechanical properties of the underwater irregularly shaped component to some extent and reduce costs. However, the ability to bond hollow spheres to the inner surface indicates that the irregularly shaped shell is open, and the filling efficiency of the buoyancy material is low. Patent CN102702679A mentions a method for preparing a high-strength solid buoyancy material for deep-sea diving, involving uniformly stirring epoxy resin and other reagents and then... After degassing, the lightweight filler is placed in a stainless steel mold. The mold is then placed on an electric vibration table and slightly vibrated to ensure the filler is compacted. A locking device is then used to secure the compacted filler in the mold. A pre-mixed epoxy mixture is injected into the mold through an injection hole at the bottom using a liquid booster pump at a pressure of 0.1–3 MPa until epoxy mixture evenly seeps from the surface of the fixed filler. The epoxy injection tube is removed, and the epoxy injection hole at the bottom of the mold is sealed. The stainless steel mold containing the epoxy mixture is placed in a drying oven and cured using a curing process: 85–90℃ for 30–60 minutes, then 100–110℃ for 120–240 minutes, and finally 140–150℃ for 60–120 minutes. This yields a solid buoyancy material for deep-sea applications, which improves the compressive strength and density of the buoyancy material. However, the use of a locking device within the stainless steel mold indicates a relatively complex preparation process, and the combined use of various steps results in a high cost. Summary of the Invention

[0005] In view of this, the present invention aims to propose a method for casting and filling buoyancy material in a closed cavity, in order to solve the problems existing in the prior art, such as difficulty in filling buoyancy material into a closed cavity, low filling efficiency during the filling process, high material cost for casting and filling buoyancy material in complex closed cavities, cumbersome filling process, low strength and density of the buoyancy material structure, and numerous gaps between the sealing material and the buoyancy material. This method effectively achieves the casting and filling of buoyancy material into a closed cavity, improves the filling efficiency, reduces material cost during the casting and filling process, simplifies the filling process of buoyancy material in a closed cavity, enhances the strength and density of the buoyancy material structure, and avoids the formation of gaps between the closed cavity and the buoyancy material.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: This invention relates to a method for casting and filling buoyancy material into a closed cavity, the method comprising the following steps: Step 1: Machining and installation of the pouring and filling device: Machining at least two circular holes in the closed cavity, and installing connecting pipes at the circular holes, which are then connected to the vacuum / pressurization system; Step 2, Pre-filling of solid buoyancy material blocks: Fill the sealed cavity with solid buoyancy material blocks through connecting pipes; Step 3: Prepare the adhesive solution; Step 4: Under the action of the vacuum / pressurization system, maintain the pressure inside the sealed cavity at a negative pressure and inject adhesive; Step 5: Before the adhesive has cured, pressurize the sealed cavity and maintain the first pressure value P1 ≥ the first pressure preset value p0. Maintain the pressure value P1 until the adhesive cures.

[0007] Furthermore, the circular hole includes an injection hole and a discharge hole, both of which are located on the closed cavity. The injection hole and discharge hole are respectively connected to the connecting pipe and filled with a material that facilitates the pouring of buoyancy components.

[0008] Furthermore, the connecting pipe includes a glue injection pipe and a glue discharge pipe. The glue injection pipe is located outside the closed cavity through a glue injection hole, and the glue discharge pipe is located outside the closed cavity through a glue discharge hole. The glue discharge pipe is connected to the vacuum / pressurization system. The vacuum / pressurization system includes a shut-off valve. Both the glue injection pipe and the glue discharge pipe are equipped with shut-off valves to control the opening and closing of the glue injection pipe and the glue discharge pipe, respectively.

[0009] Furthermore, the shut-off valve includes a first shut-off valve and a second shut-off valve. The first shut-off valve is located outside the glue injection pipe, and the second shut-off valve is located outside the glue discharge pipe.

[0010] Furthermore, the height of the glue injection tube is H1mm, the height of the glue discharge tube is H2mm, and H2-H1≥the preset height difference h0.

[0011] Furthermore, step two specifically includes: pre-filling of solid buoyancy material blocks: filling the solid buoyancy material block fragments into the closed cavity through the glue injection tube in the connecting pipe, wherein the ratio of the volume of the solid buoyancy material block filling to the volume inside the closed cavity is a% ≥ the preset filling volume ratio a0%, and the maximum size of the solid buoyancy material block d1mm < the diameter of the glue injection tube d2mm.

[0012] Furthermore, step three includes: Step S31: Select component A and component B of the adhesive solution; Step S32: Stir the mixture of components A and B evenly using a stirrer; Step S33: When there are no particles or sediments in the mixture, put the mixture into the defoaming device until no bubbles overflow from the surface of the mixture to obtain the desired adhesive solution.

[0013] Furthermore, in step four, the vacuum / pressurization system includes a vacuum system and a pressurization system, both of which are connected to the discharge pipe.

[0014] Furthermore, step four includes: Step S41: Open the vacuum system and shut-off valves in the vacuum / pressurization system to purge the air from the sealed cavity; Step S42: Close the shut-off valve 2 to maintain the pressure in the closed cavity as negative pressure, wherein the second pressure value P2 in the closed cavity is less than or equal to the second pressure preset value p1, and the pressure holding time is the pressure holding time t1min; Step S43: Open the shut-off valve and take an appropriate amount of buoyancy material adhesive and slowly inject it into the closed cavity through the injection tube; Step S44: Determine whether the adhesive overflows from the outlet of the dispensing tube. If yes, stop the dispensing action and proceed to step S45. If no, continue dispensing. Step S45: When the glue injection action is stopped, determine whether the glue in the glue discharge tube has a backflow amplitude A ≤ preset backflow amplitude value a. If yes, proceed to step S46; otherwise, return to step S43. Step S46: Immediately close the shut-off valve, stop the glue injection, and perform negative pressure defoaming treatment, wherein the treatment time is the preset defoaming treatment time t2min.

[0015] Furthermore, step five includes: Step 51: Before the adhesive has cured, turn on the pressurization system in the vacuum / pressurization system to pressurize the solid buoyancy material block and adhesive in the sealed cavity; Step S52: Determine whether the current first pressure value P1 of the sealed cavity is greater than or equal to the first pressure preset value p0. If yes, proceed to step S53; otherwise, return to step S51. Step S53: Maintain the first pressure value P1 until the adhesive solidifies, thus obtaining a component filled with buoyancy material in a closed cavity.

[0016] Compared with the prior art, the method for casting and filling buoyancy material in a closed cavity described in this invention has the following advantages: The filling method described above can effectively fill buoyancy material into a sealed cavity, improving the filling efficiency, reducing material costs, simplifying the filling process, enhancing the strength and density of the buoyancy material structure, and increasing its compressive strength. Furthermore, it avoids gaps between the sealed cavity and the buoyancy material. The negative pressure filling and pressure curing method ensures the buoyancy material completely fills the sealed cavity, resulting in a filler without air bubbles or gaps with the frame, thus improving filling efficiency and the compressive strength of the buoyancy material structure. Attached Figure Description

[0017] The accompanying drawings, which constitute a part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic front view of a complex, sealed cavity structure; Figure 2 A schematic diagram of a complex, sealed cavity structure (right view). Figure 3 A bottom view schematic diagram of a complex, sealed cavity structure; Figure 4 A three-dimensional schematic diagram of a complex, sealed cavity structure; Figure 5 Schematic diagram of filling buoyancy material into a closed cavity – connecting the closed cavity to the casting pipe and vacuum / pressurization system; Figure 6 Schematic diagram of filling a closed cavity with buoyancy material – filling with solid buoyancy material blocks; Figure 7 Schematic diagram of buoyancy material block filling for buoyancy material pouring and filling in a closed cavity.

[0018] Explanation of reference numerals in the attached drawings: 1. Enclosed cavity; 2. Circular hole; 21. Injection hole; 22. Drain hole; 3. Connecting pipe; 31. Injection tube; 32. Drain tube; 4. Vacuum / pressurization system; 5. Solid buoyancy material block; 6. Adhesive liquid; 7. Shut-off valve; 71. Shut-off valve one; 72. Shut-off valve two. Detailed Implementation

[0019] The inventive concepts of this disclosure will be described below using terminology commonly used by those skilled in the art to communicate the essence of their work to others skilled in the art. However, these inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] In existing technologies, the main buoyancy components for deep-sea applications are made of epoxy-based / hollow glass microsphere composite solid buoyancy materials. Under the pressure of deep seawater, the shrinkage deformation of the buoyancy components is much greater than that of the main structure of the submersible. If the installation and filling design of the buoyancy components are unreasonable, or if there are gaps between the buoyancy materials after filling, the buoyancy components of the submersible may loosen under the pressure of deep water, or even crack due to excessive stress caused by filling or installation. Usually, the main structure of the underwater equipment can be directly connected to the buoyancy material, that is, the buoyancy material can be connected to the metal frame by using double-ended screws, or the buoyancy material can be cut into prefabricated blocks and filled into the metal frame of the underwater equipment and fixed with adhesive. However, for closed cavity structures, it is not possible to install buoyancy materials inside using screws or adhesives, and the frame cannot be filled using traditional filling processes.

[0024] To address the problems in existing technologies, such as difficulty in filling buoyancy materials into sealed cavities, low filling efficiency, high material costs for pouring and filling buoyancy materials into complex sealed cavities, cumbersome filling processes, low strength and density of the buoyancy material structure, and numerous gaps between the sealing material and the buoyancy material, this embodiment proposes a method for pouring and filling buoyancy materials into sealed cavities. The method includes the following steps: Step 1: Processing and installation of the pouring and filling device: Machining at least two circular holes 2 into the closed cavity 1, and setting a connecting pipe 3 at the circular holes 2. The connecting pipe 3 is connected to the vacuum / pressurization system 4. The circular holes 2 are all through the closed cavity 1 to facilitate the connection between the connecting pipe 3 and the closed cavity 1. Step 2, Pre-filling of solid buoyancy material block 5: The solid buoyancy material block 5 is filled into the closed cavity 1 through the connecting pipe 3. The number of connecting pipes 3 corresponds to the number of round holes 2, which are used to guide the flow and seal the cavity. Step 3: Prepare adhesive solution 6; Step 4: Under the action of the vacuum / pressurization system 4, maintain the pressure inside the sealed cavity 1 at a negative pressure and inject glue. In this embodiment, negative pressure means that the pressure value is negative. Step 5: Before the adhesive 6 has cured, pressurize the sealed cavity 1 and maintain the first pressure value P1 ≥ the first pressure preset value p0. Maintain the pressure value P1 until the adhesive 6 has cured. Preferably, p0 is 1 Bar, but it is not limited to this in practice.

[0025] By employing the method described above, pre-filled pre-fabricated solid buoyancy material blocks 5 are used, followed by negative pressure casting of adhesive 6 to fill the buoyancy material inside the sealed cavity 1. This effectively achieves the filling of buoyancy material into the sealed cavity, improves the filling efficiency of buoyancy material casting, reduces material costs during the buoyancy material casting process, simplifies the filling process of buoyancy material in the sealed cavity, enhances the strength and density of the buoyancy material structure, and avoids the formation of gaps between the sealed cavity and the buoyancy material.

[0026] The circular hole 2 includes an injection hole 21 and an outlet hole 22, both of which are located on the enclosed cavity 1. The injection hole 21 and outlet hole 22 are connected to the connecting pipe 3 for filling with buoyancy material components. The diameters D1mm of the injection hole 21 and D2mm of the outlet hole 22 are both greater than or equal to the preset diameter D0mm of the circular hole. The values ​​of D0, D1, and D2 are set as needed. The connecting pipe 3 includes an injection pipe 31 and an outlet pipe 32. The injection pipe 31 is located outside the enclosed cavity 1 through the injection hole 21, and the outlet pipe 32 is located outside the enclosed cavity 1 through the outlet hole 22. The outlet pipe 32 is connected to the vacuum / pressurization system 4. The injection pipe 31 is used to fill the solid buoyancy material block 5 and the buoyancy material injection port. The adhesive 6 is poured into the inlet. The vacuum / pressurization system 4 includes a shut-off valve 7. Both the glue injection pipe 31 and the glue discharge pipe 32 are equipped with shut-off valves 7 to control the opening and closing of the glue injection pipe 31 and the glue discharge pipe 32, respectively. The height of the glue injection pipe 31 is H1mm, and the height of the glue discharge pipe 32 is H2mm. H2-H1 ≥ preset height difference h0. The value of h0 is set according to the requirements, but is not limited to this. The shut-off valve 7 includes a first shut-off valve 71 and a second shut-off valve 72. The first shut-off valve 71 is located outside the glue injection pipe 31, and the second shut-off valve 72 is located outside the glue discharge pipe 32. In this embodiment, "height" refers to the distance value of the glue injection pipe 31 in the direction perpendicular to the connection surface of the closed cavity 1. Preferably, h0 is 100mm and D0 is φ50mm.

[0027] The circular hole 2 facilitates communication between the connecting pipe 3 and the closed cavity 1. The connecting pipe 3 facilitates flow guidance and allows for effective judgment of whether the injection of the adhesive 6 is complete, preventing direct overflow from the closed cavity 1, which would increase the complexity of the buoyancy material pouring and filling operation, avoid material waste, and reduce material costs. In addition, the connection between the connecting pipe 3 and the vacuum / pressurization system 4 facilitates pressurization and vacuuming of the closed cavity 1, allowing for timely degassing of the contents of the closed cavity 1 before the adhesive 6 cures during the buoyancy material pouring process, thus preventing the formation of gaps between the cured buoyancy material and the closed cavity 1.

[0028] Step two specifically includes: pre-filling of solid buoyancy material block 5: First, the closed cavity 1 structure is fixedly placed using a fixing fixture. The solid buoyancy material block 5 fragments are filled into the closed cavity 1 through the glue injection tube 31 in the connecting pipe 3. The ratio of the volume of solid buoyancy material block 5 to the volume of the closed cavity 1 is a% ≥ the preset filling volume ratio a0%. At this time, the solid buoyancy material block 5 fills the entire closed cavity 1. The maximum size of solid buoyancy material block 5 is d1mm < the diameter of glue injection tube 31 is d2mm. In this embodiment, the sizes of a0, d1, and d2 are set according to the requirements.

[0029] By selecting an appropriate amount of solid buoyancy material blocks 5 for pre-filling, the foundation for the preparation of buoyancy material inside the closed cavity 1 is effectively laid. This is beneficial to improving the density between buoyancy materials, while reducing the use of other components in the buoyancy material. It can also resist the force of the vacuum / pressurization system 4, thereby improving the strength and density of the prepared buoyancy material. The solid buoyancy material blocks 5 are in the form of fragments, which is beneficial to entering the closed cavity 1 through the glue injection tube 31, which can greatly improve the filling efficiency and shorten the filling time.

[0030] Step three includes: Step S31: Select component A and component B of adhesive 6, wherein component A and component B are resin and filler, respectively; Step S32: Stir the mixture of component A and component B evenly using a stirrer, that is, stir the mixture including resin and filler evenly using a stirrer. Step S33: When there are no particles or sediments in the mixture, put the mixture into a defoaming device until no bubbles overflow from the surface of the mixture to obtain the desired adhesive 6. In this process, after the resin and filler are mixed evenly, vacuum-assisted defoaming is performed, with the vacuum degree maintained between -1 Bar and -0.1 Bar. The standing time is about 10 min to 40 min. At room temperature of 25°C, the viscosity of the mixed adhesive 6 is in the range of 1000 mPa·s to 10000 mPa·s. In this embodiment, the filler includes glass microspheres, but it is not limited to this.

[0031] By selecting, stirring, and defoaming the ingredients of adhesive 6, the purity of adhesive 6 can be improved, avoiding the presence of excessive air bubbles, which could affect the buoyancy material after injection and reduce its strength. Pretreatment of adhesive 6 can significantly reduce the possibility of impurities in it, minimize the impact of sediments or particles on the filling of the buoyancy material, and also improve the adhesion of adhesive 6 and increase its filling rate.

[0032] Step four, the vacuum / pressurization system 4, includes a vacuum system and a pressurization system, both of which are connected to the discharge hose 32; specifically, step four includes: Step S41: Open the vacuum system and shut-off valve 72 in the vacuum / pressurization system 4 to purge the air from the sealed cavity 1; Step S42: Close the shut-off valve 72 to maintain the pressure inside the closed cavity 1 as negative pressure. The second pressure value P2 inside the closed cavity 1 is less than or equal to the second pressure preset value p1. The pressure holding time is t1 min, and the value of t1 ranges from 10 min to 30 min. The range of the second pressure value P2 in the vacuum system auxiliary pressure is -1 Bar to -0.1 Bar. Preferably, p1 is -0.95 Bar. Step S43: Open the shut-off valve 71, take an appropriate amount of buoyancy material adhesive 6 and slowly inject it into the closed cavity 1 through the adhesive inlet of the adhesive injection tube 31; Step S44: Determine whether the adhesive 6 overflows from the outlet of the adhesive drain pipe 32, i.e., the outlet shown in the figure. If yes, stop the adhesive injection and proceed to step S45. If no, continue the adhesive injection. Step S45: When the glue injection action is stopped, determine whether the backflow amplitude A of the glue 6 in the glue discharge pipe 32 is less than or equal to the preset backflow amplitude value a. The value of a is set according to the requirements. If yes, proceed to step S46; otherwise, return to step S43. Step S46: Immediately close the shut-off valve 71 to stop the glue injection and perform negative pressure defoaming treatment. The treatment time is the preset defoaming treatment time t2min, where t2 ranges from 5min to 30min. Alternatively, if the glue material reserved at the outlet of the glue discharge pipe 32 does not completely flow back within the preset defoaming treatment time t2 when the negative pressure is applied, then allow it to stand and cure. The value of t2 ranges from 5min to 60min.

[0033] By using the auxiliary pressure of the vacuum system and employing negative pressure assisted casting, air bubbles inside the casting body can be eliminated, improving the density of the buoyancy material, reducing internal defects, and increasing the compressive strength of the buoyancy material. In addition, the buoyancy material casting and filling technology involves first filling the cavity with solid buoyancy material blocks 5 and then pouring in mixed adhesive (a mixture of resin / filler, etc.), which can improve the casting and filling efficiency, enhance the structural strength, and prevent the buoyancy material from burning due to heat accumulation during curing.

[0034] Step five includes: Step 51: Before the adhesive 6 has cured, turn on the pressurization system in the vacuum / pressurization system 4 to pressurize the solid buoyancy material block 5 and the adhesive 6 in the closed cavity 1. That is, after the solid buoyancy material block 5 and the adhesive 6 are poured and filled in the closed cavity 1 with vacuum assistance, pressurization is performed before the adhesive 6 has cured. Step S52: Determine whether the current first pressure value P1 of the sealed cavity 1 is greater than or equal to the first pressure preset value p0. If yes, proceed to step S53; otherwise, return to step S51. Step S53: Maintain the first pressure value P1 until the adhesive 6 solidifies, and obtain the buoyancy material casting and filling component in the closed cavity 1, i.e., the casting type buoyancy material; wherein, the pressurization system maintains the first pressure value P1 in the range of 1 Bar-50 Bar, preferably, p0 is 1 Bar.

[0035] By applying pressure to assist in the curing and molding of the incompletely cured adhesive 6, the pressure allows the liquid buoyancy material to flow fully before curing, filling every pore inside the complex structural cavity. This prevents gaps between the buoyancy material and the closed cavity 1 due to insufficient filling, greatly reducing the possibility of gaps between the buoyancy material and the closed cavity 1. Simultaneously, this buoyancy material casting technology can be applied to the filling of buoyancy materials inside closed cavity shells. Unlike traditional methods that use open shells to fill buoyancy materials or use locking devices to make the buoyancy material preparation device closed, this application allows direct filling of buoyancy materials inside the closed cavity 1, significantly increasing the filling range, simplifying the filling process, improving filling efficiency, and broadening the application scope of buoyancy materials in the fields of ships and underwater equipment. The negative pressure filling and pressure curing method ensures that the buoyancy material fills the closed cavity 1 densely, obtaining a filler without internal air bubbles and gaps with the skeleton, improving filling efficiency. This method improves the efficiency and pressure resistance of buoyancy material structures, enhancing the filling efficiency and quality of cast buoyancy materials. Furthermore, two circular holes 2 are first machined at the top of the closed cavity 1, designated as injection holes 21 and discharge holes 22. Before casting the buoyancy material, pre-filled solid buoyancy material blocks 5 are introduced into the cavity structure through injection holes 21. A mixture of resin and fillers is then injected under negative pressure through the top injection holes 21. Negative pressure removes air pores from the buoyancy material casting, improving the strength of the buoyancy structure. After casting, pressure-assisted curing is performed before solidification to increase the filling rate of the buoyancy material within the cavity and prevent air pores between the buoyancy material and the inner wall of the complex cavity shell. This method solves the problem of filling buoyancy materials inside closed cavity structures, improves the preparation efficiency of buoyancy materials, reduces material costs, and provides a better solution for filling applications inside closed cavity structures. The method boasts high filling efficiency and quality, meeting the filling requirements of irregularly shaped cavities, and has promising applications and prospects in underwater equipment or buoyancy material filling.

[0036] Example 1

[0037] Select a 1m³ enclosed cavity 1 structure. Two φ100mm diameter circular holes 2 are machined 700mm apart on the top surface of the enclosed cavity 1. These holes are connected to a 500mm injection tube 31 and a 300mm discharge tube 32, respectively. The discharge tube 32 is 300mm higher vertically than the injection tube 31. The discharge tube 32 is connected to a vacuum / pressurization system 4. Fill the enclosed cavity 1 with solid buoyancy material blocks 5 through the injection tube 31. Take 20kg of a mixture of epoxy resin and glass microsphere filler (i.e., adhesive liquid 6), with a viscosity of approximately 6000mPa·s at 25℃, and place it in a closed defoaming system for 20 minutes to defoam. Close the shut-off valve 71, connect the container to a vacuum device to create a negative pressure of -1Bar, maintain this for approximately 5 minutes, and expel air from the cavity. Connect the adhesive liquid 6 to the injection tube 31, and adjust the negative pressure to -1Bar. 0.7 Bar, open shut-off valve 71, and slowly introduce the settled mixed adhesive (i.e., adhesive 6) into the cavity structure under negative pressure. After the adhesive exits from the discharge pipe 32, close shut-off valve 72. Then maintain a static negative pressure of about -0.9 Bar for 10 minutes to remove internal air bubbles. Before the adhesive (i.e., adhesive 6) cures, open the pressurization system to about 30 Bar. If the adhesive (i.e., adhesive 6) in the discharge pipe 32 has not completely flowed back after 40 minutes, allow it to stand under pressure for curing.

[0038] Example 2

[0039] A 0.5m³ closed cavity 1 structure is selected. Two φ60mm diameter circular holes 2 are machined 400mm apart on the top surface of the closed cavity 1. These holes are connected to a 500mm high glue injection tube 31 and a 300mm high glue discharge tube 32, respectively. The vertical height of the discharge tube 32 is 100mm higher than that of the glue injection tube. The discharge tube 32 is connected to a vacuum / pressurization system 4. Solid buoyancy material blocks 5 are filled through the glue injection tube 31 to fill the closed cavity 1. Take 10kg of a mixture of epoxy resin and glass microsphere filler (i.e., adhesive liquid 6), with a viscosity of approximately 2000mPa·s at 25℃, and place it in a closed defoaming system for 10 minutes to defoam. Close the shut-off valve 71 and use... Vacuum equipment is connected to the container and evacuated to a negative pressure of -0.5 Bar, maintained for about 10 minutes, to expel air from the cavity. The adhesive (i.e., liquid adhesive 6) is connected to the dispensing tube 31, and the negative pressure is adjusted to -0.4 Bar. The first shut-off valve 71 is opened, and the mixed adhesive (i.e., liquid adhesive 6) after standing is slowly introduced into the cavity structure under the assistance of negative pressure. After the adhesive is discharged from the dispensing tube 32, the second shut-off valve 72 is closed. Then, the negative pressure is maintained at about -0.7 Bar for 15 minutes to remove internal air bubbles. Before the adhesive (i.e., liquid adhesive 6) cures, the pressurization system is opened at about 5 Bar. If the adhesive (i.e., liquid adhesive 6) in the dispensing tube has not completely flowed back after 20 minutes, it is allowed to stand under pressure for curing.

[0040] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for casting and filling buoyancy material into a closed cavity, characterized in that, The method includes the following steps: Step 1: Processing and installation of the pouring and filling device: Machining at least two round holes (2) into the closed cavity (1), and setting a connecting pipe (3) at the round hole (2), and connecting pipe (3) to the vacuum / pressurization system (4); Step 2, Pre-filling of solid buoyancy material block (5): Fill the solid buoyancy material block (5) into the closed cavity (1) through the connecting pipe (3); Step 3: Prepare the adhesive solution (6); Step 4: Under the action of the vacuum / pressurization system (4), maintain the pressure inside the closed cavity (1) at a negative pressure and inject adhesive; Step 5: Before the adhesive (6) has cured, pressurize the sealed cavity (1) and keep the first pressure value P1 ≥ the first pressure preset value p0. Keep the pressure value P1 until the adhesive (6) cures. Step 2 specifically includes: pre-filling of solid buoyancy material block (5): filling the solid buoyancy material block (5) fragments into the closed cavity (1) through the glue injection tube (31) in the connecting pipe (3), wherein the ratio of the volume of the solid buoyancy material block (5) filling to the volume inside the closed cavity (1) is a% ≥ the preset filling volume ratio a0%, and the maximum size of the solid buoyancy material block (5) d1mm < the diameter of the glue injection tube (31) d2mm; Step three includes: Step S31: Select component A and component B of the adhesive solution (6); Step S32: Stir the mixture of components A and B evenly using a stirrer; Step S33: When there are no particles or sediments in the mixture, put the mixture into the defoaming device until no bubbles overflow from the surface of the mixture to obtain the required adhesive (6); Step five includes: Step 51: Before the adhesive (6) has cured, turn on the pressurization system in the vacuum / pressurization system (4) to pressurize the solid buoyancy material block (5) and the adhesive (6) in the closed cavity (1); Step S52: Determine whether the cavity is closed (1) If the current first pressure value P1 ≥ the first pressure preset value p0, then proceed to step S53; otherwise, return to step S51. Step S53: Maintain the first pressure value P1 until the adhesive (6) solidifies, and obtain the component with the buoyancy material poured and filled in the closed cavity (1); wherein, pressurization can make the liquid buoyancy material flow fully before solidification and fill each pore inside the complex structure cavity; prevent insufficient filling from causing gaps between the buoyancy material and the closed cavity (1).

2. The method for casting and filling buoyancy material in a closed cavity according to claim 1, characterized in that, The circular hole (2) includes an injection hole (21) and a discharge hole (22). The injection hole (21) and the discharge hole (22) are both located on the closed cavity (1). The injection hole (21) and the discharge hole (22) are respectively connected to the connecting pipe (3) and filled with a solid buoyancy material block (5) for easy injection.

3. The method for casting and filling buoyancy material in a closed cavity according to claim 2, characterized in that, The connecting pipe (3) includes a glue injection pipe (31) and a glue discharge pipe (32). The glue injection pipe (31) is set outside the closed cavity (1) through the glue injection hole (21), and the glue discharge pipe (32) is set outside the closed cavity (1) through the glue discharge hole (22). The glue discharge pipe (32) is connected to the vacuum / pressurization system (4). The vacuum / pressurization system (4) includes a shut-off valve (7). Both the glue injection pipe (31) and the glue discharge pipe (32) are equipped with shut-off valves (7) to control the opening and closing of the glue injection pipe (31) and the glue discharge pipe (32) respectively.

4. The method for casting and filling buoyancy material in a closed cavity according to claim 3, characterized in that, The shut-off valve (7) includes a first shut-off valve (71) and a second shut-off valve (72). The first shut-off valve (71) is located outside the glue injection pipe (31), and the second shut-off valve (72) is located outside the glue discharge pipe (32).

5. The method for casting and filling buoyancy material in a closed cavity according to claim 4, characterized in that, The height of the glue injection tube (31) is H1mm, the height of the glue discharge tube (32) is H2mm, and H2-H1≥the preset height difference h0.

6. The method for casting and filling buoyancy material in a closed cavity according to claim 5, characterized in that, The vacuum / pressurization system (4) in step four also includes a vacuum system, and both the vacuum system and the pressurization system are connected to the glue discharge pipe (32).

7. The method for casting and filling buoyancy material in a closed cavity according to claim 6, characterized in that, Step four includes: Step S41: Open the vacuum system and shut-off valve (72) in the vacuum / pressurization system (4) to discharge the air inside the closed cavity (1); Step S42: Close the shut-off valve (72) and keep the pressure inside the closed cavity (1) negative, wherein the second pressure value P2 inside the closed cavity (1) is less than or equal to the second pressure preset value p1, and the pressure holding time is the pressure holding time t1min; Step S43: Open the shut-off valve (71), take an appropriate amount of buoyancy material adhesive (6) and slowly inject it into the closed cavity (1) through the glue injection tube (31); Step S44: Determine whether the adhesive (6) overflows from the outlet of the adhesive drain pipe (32). If yes, stop the adhesive injection action and proceed to step S45. If no, continue the adhesive injection. Step S45: When the glue injection action is stopped, determine whether the glue liquid (6) in the glue discharge pipe (32) has a backflow amplitude A ≤ preset backflow amplitude value a. If yes, proceed to step S46; otherwise, return to step S43. Step S46: Immediately close the shut-off valve (71), stop the glue injection, and perform negative pressure defoaming treatment, wherein the treatment time is the preset defoaming treatment time t2min.

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