Metal bushing for composite material tanks and method for manufacturing same

Abstract

The present application relates to the field of composite material storage tank connecting piece, and specifically provides a metal bushing for composite material storage tank, which comprises a metal bushing body, a deformation groove one and a deformation groove two on the outer wall of the metal bushing body, and rubber coating layers in the deformation groove one and the deformation groove two, wherein the metal bushing is located in the bushing mounting hole of the composite material storage tank after installation. The present application also provides a preparation method of the metal bushing for composite material storage tank, which comprises the following steps: S1, preparing the metal bushing body by machining, and opening the deformation groove one and the deformation groove two; S2, coating rubber coating layers in the deformation groove one and the deformation groove two; S3, curing the rubber coating layers; S4, coating adhesive; and S5, installing the metal bushing body coated with adhesive into the bushing mounting hole of the composite material storage tank. The present application can ensure the sealing performance of the composite material storage tank connecting bushing position.

Description

Technical Field

[0001] This invention relates to the field of composite material tank connectors, and in particular to a metal bushing for a composite material tank and its preparation method. Background Technology

[0002] Propellant tanks are key components of the propulsion and structural systems of space launch vehicles, and the level of lightweight materials used in propellant tanks is one of the main performance indicators of the launch vehicle. Currently, the development of materials for space launch vehicle propellant tanks has mainly gone through stages such as aluminum-magnesium alloys, aluminum-copper alloys, aluminum-lithium alloys, and composite materials. Composite material tanks have gradually developed from small diameter and small capacity towards large diameter and large capacity. With the vigorous development of new energy vehicles both domestically and internationally, the application of composite material tanks in hydrogen fuel cell vehicles is also receiving increasing attention. Compared with traditional metal structure tanks, composite material tanks have significant advantages in terms of weight and cost. Studies have shown that using composite material tanks in space launch vehicles can reduce the overall structural weight by 20% to 40%.

[0003] Based on the application scenarios and environments of propellant tanks, the sealing performance of composite material tanks has a crucial impact on the performance of space launch vehicles. The sealing performance of composite material tanks comprises two parts: one is the sealing performance of the composite material itself, primarily ensured through structural and process design; the other is the sealing of the joints within the tank (pressure vessels in aerospace applications require connections between assembled components). Due to the low interlaminar strength of composite materials, directly providing threads on them easily leads to interlaminar failure, making direct threading impossible. Therefore, composite material tanks are mostly connected using metal connectors, typically provided through pre-embedded or post-assembly methods. However, traditional pre-embedded or post-assembly metal connectors often suffer from gaps between the metal and composite materials due to the significant difference in thermal expansion coefficients between the metal and the composite material. When the tank undergoes high / low temperature cycling or load cycling, this can lead to seal failure.

[0004] In conclusion, how to design a metal connector that can guarantee the sealing performance of composite material tanks is an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a metal bushing for composite material tanks and its preparation method. The metal bushing can be used on composite material tanks and provides connections between the tank and other equipment or compartments, thus solving the problem of poor airtightness at the connection points of existing metal bushings under high and low temperature cycles and load cycles in tanks.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a metal bushing for a composite material storage tank, comprising a metal bushing body, wherein deformation groove one and deformation groove two are respectively formed on the outer wall of the metal bushing body along the circumferential direction and the longitudinal direction parallel to the axial direction; the outer wall of the metal bushing body located between deformation groove one and deformation groove two forms a connecting wall that directly contacts the composite material storage tank; both deformation groove one and deformation groove two are coated with a rubber coating layer; when the metal bushing is installed, the metal bushing is located in the bushing mounting hole of the composite material storage tank, and the rubber coating layer and the connecting wall are bonded to the hole wall of the bushing mounting hole using an adhesive.

[0007] Preferably, the first deformation groove is an annular groove and the first deformation groove divides the connecting wall into multiple cylindrical connecting blocks; the second deformation groove is a rectangular groove and the second deformation groove divides the cylindrical connecting blocks into multiple independent arc-shaped connecting blocks; after the metal bushing is installed, it is bonded to the hole wall of the bushing mounting hole through the rubber covering layer and the arc-shaped connecting blocks.

[0008] Preferably, the outer surface of the rubber coating layer is located within deformation groove one and deformation groove two and is flush with the outer surface of the arc-shaped connecting block.

[0009] Preferably, the metal bushing body has at least one deformation groove one and two deformation groove two, the height H1 of deformation groove one and the width H2 of deformation groove two are both 1mm-3mm.

[0010] Preferably, the rubber coating has a service temperature range of -50℃ to 250℃, a tensile strength ≥1MPa, an elongation at break ≥200%, and an adhesion strength to the metal bushing body ≥1MPa.

[0011] Preferably, the material of the rubber coating layer is nitrile rubber or silicone rubber.

[0012] Preferably, the metal bushing body is made of steel, titanium alloy, aluminum alloy, or magnesium alloy.

[0013] A method for preparing a metal bushing for a composite material storage tank, comprising the following steps:

[0014] S1: The metal bushing body is prepared by machining, and deformation groove one and deformation groove two are opened on the metal bushing body;

[0015] S2: Apply a rubber coating layer to the deformation groove one and deformation groove two;

[0016] S3: Curing the rubber coating layer;

[0017] S4: Apply adhesive to the outer surface of the rubber coating layer and the arc-shaped connecting block;

[0018] S5: Install the metal bushing body coated with adhesive into the bushing mounting hole of the composite material tank.

[0019] Preferably, the curing temperature of the rubber coating layer in step S3 is room temperature; after the rubber coating layer is cured, the rubber coating layer that protrudes to the outside of deformation groove one and deformation groove two is repaired until the outer surface of the rubber coating layer is located in deformation groove one and deformation groove two and is flush with the outer surface of the arc-shaped connecting block.

[0020] Preferably, the rubber coating layer in step S2 is coated by: applying raw rubber sheet under pressure and curing, or by injecting liquid rubber through a mold, or by manual coating.

[0021] The beneficial effects of this invention are:

[0022] 1. The present invention provides deformation groove one and deformation groove two in the circumferential and longitudinal directions of the metal bushing, respectively, and coats the deformation groove one and deformation groove two with a certain thickness of rubber coating layer. It can adjust the thermal expansion coefficient of the composite material and the metal under high and low temperature environments, and adjust the strain difference at the connection point of the metal and the composite material under cyclic load (internal pressure, external normal stress and shear stress) environment, so as to ensure the sealing performance of the metal bushing position and the connection position.

[0023] 2. In this invention, the first deformation groove divides the connecting wall into multiple cylindrical connecting blocks, and the second deformation groove divides the cylindrical connecting blocks into multiple independent arc-shaped connecting blocks. After the metal bushing is installed, it is bonded to the wall of the bushing mounting hole through the arc-shaped connecting blocks. When the ambient temperature changes, the surface of the metal bushing in contact with the composite material consists of individual and dispersed arc-shaped connecting blocks, which can effectively ensure the bonding strength at the direct contact point between the metal bushing and the composite material tank. At the same time, through a portion of the outer surface of the bushing, i.e. the arc-shaped connecting blocks, it is directly bonded to the composite material tank through structural adhesive, which can ensure that the metal bushing will not rotate in the bushing mounting hole when the internal thread is connected and torque is applied by instruments and equipment, thus ensuring the stability of installation and connection. Attached Figure Description

[0024] Figure 1 This is a front view structural schematic diagram of the metal bushing body provided in an embodiment of the present invention.

[0025] Figure 2 This is a top view of the metal bushing body provided in an embodiment of the present invention.

[0026] Figure reference numerals: Deformation groove 1, Deformation groove 2, Arc-shaped connecting block 3, Internal threaded hole 4. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-2The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0028] A metal bushing for a composite material storage tank includes a metal bushing body, which is made of steel, titanium alloy, aluminum alloy, or magnesium alloy. Figure 1 and Figure 2 As shown, a deformation groove 1 is formed along the circumferential direction N on the outer wall of the metal bushing body, and a deformation groove 2 is formed along the longitudinal direction parallel to the axial direction M on the outer wall of the metal bushing body. The outer wall of the metal bushing body located between the deformation groove 1 and the deformation groove 2 forms a connecting wall that directly contacts the storage tank. The deformation groove 1 is an annular groove and divides the connecting wall into multiple cylindrical connecting blocks. The deformation groove 2 is a rectangular groove and divides the cylindrical connecting blocks into multiple independent arc-shaped connecting blocks 3. The middle part of the metal bushing includes an internal threaded hole 4, which is threadedly connected to the relevant parts of the machine body. After the metal bushing is installed, the metal bushing is located in the bushing mounting hole of the composite material storage tank, and the rubber covering layer and the connecting wall are bonded to the hole wall of the bushing mounting hole with adhesive.

[0029] The metal bushing body has at least one deformation groove 1 and two deformation grooves 2. The height H1 of deformation groove 1 and the width H2 of deformation groove 2 are both 1mm-3mm, preferably 2mm. In this embodiment, a total of two deformation grooves 1 and four deformation grooves 2 are evenly provided. Those skilled in the art can also set other numbers and positions of deformation grooves 1 and deformation grooves 2 according to the actual situation.

[0030] Both deformation groove 1 and deformation groove 2 are coated with a rubber coating layer. The outer surface of the rubber coating layer is located inside deformation groove 1 and deformation groove 2 and is flush with the outer surface of the arc-shaped connecting block 3. That is, the thickness of the rubber coating layer does not exceed the depth of deformation groove 1 and deformation groove 2. Preferably, the outer surface of the rubber coating layer is flush with the outer surface of the arc-shaped connecting block 3, that is, the thickness of the rubber coating layer is equal to the depth of deformation groove 1 and deformation groove 2. In this embodiment, the operating temperature range of the rubber coating layer is -50℃ to 250℃, the tensile strength is ≥1MPa, the elongation at break is ≥200%, and the adhesion strength to the metal bushing body is ≥1MPa. The material of the rubber coating layer is nitrile rubber or silicone rubber.

[0031] A method for preparing a metal bushing for a composite material storage tank, comprising the following steps:

[0032] S1: The metal bushing body is prepared by machining, and deformation groove 1 and deformation groove 2 are opened on the metal bushing body;

[0033] S2: Apply a rubber coating layer to the deformation groove 1 and deformation groove 2; the rubber coating layer is applied by: pressing and curing raw rubber sheet, or injecting liquid rubber through a mold, or applying it manually.

[0034] S3: Cure the rubber coating at room temperature; after curing the rubber coating, repair the rubber coating that protrudes to the outside of deformation groove 1 and deformation groove 2 until the outer surface of the rubber coating is located inside deformation groove 1 and deformation groove 2 or flush with the outer surface of the arc-shaped connecting block 3.

[0035] S4: Apply adhesive to the outer surface of the rubber coating layer and the arc-shaped connecting block 3; the adhesive used is an epoxy adhesive or other adhesive used for bonding metal and composite materials;

[0036] S5: Install the metal bushing body coated with adhesive into the bushing mounting hole of the composite material storage tank. At this time, the outer surface of the rubber coating layer and the arc-shaped connecting block 3 are bonded to the inner wall of the bushing mounting hole.

[0037] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0038] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A metal bushing for a composite material storage tank, comprising a metal bushing body, characterized in that, Deformation groove 1 (1) and deformation groove 2 (2) are respectively provided on the outer wall of the metal bushing body along the circumferential direction and the longitudinal direction parallel to the axial direction. The outer wall of the metal bushing body located between deformation groove 1 (1) and deformation groove 2 (2) forms a connecting wall that directly contacts the composite material storage tank. Both deformation groove 1 (1) and deformation groove 2 (2) are coated with a rubber covering layer. After the metal bushing is installed, the metal bushing is located in the bushing mounting hole of the composite material storage tank and the rubber covering layer and the connecting wall are bonded to the hole wall of the bushing mounting hole with adhesive.

2. The metal bushing for a composite material storage tank according to claim 1, characterized in that, The first deformation groove (1) is an annular groove and the first deformation groove (1) divides the connecting wall into multiple cylindrical connecting blocks; the second deformation groove (2) is a rectangular groove and the second deformation groove (2) divides the cylindrical connecting blocks into multiple independent arc-shaped connecting blocks (3); after the metal bushing is installed, it is bonded to the hole wall of the bushing mounting hole through the rubber covering layer and the arc-shaped connecting blocks (3).

3. The metal bushing for a composite material storage tank according to claim 2, characterized in that, The outer surface of the rubber coating layer is located within deformation groove one (1) and deformation groove two (2) and is flush with the outer surface of the arc-shaped connecting block (3).

4. The metal bushing for a composite material storage tank according to claim 3, characterized in that, The metal bushing body has at least one deformation groove (1) and two deformation grooves (2), the height H1 of the deformation groove (1) and the width H2 of the deformation groove (2) are both 1mm-3mm.

5. The metal bushing for a composite material storage tank according to any one of claims 1-4, characterized in that, The rubber coating has a service temperature range of -50℃ to 250℃, a tensile strength ≥1MPa, an elongation at break ≥200%, and an adhesion strength to the metal bushing body ≥1MPa.

6. The metal bushing for a composite material storage tank according to claim 5, characterized in that, The material of the rubber coating layer is nitrile rubber or silicone rubber.

7. The metal bushing for a composite material storage tank according to claim 6, characterized in that, The metal bushing body is made of steel, titanium alloy, aluminum alloy, or magnesium alloy.

8. A method for preparing a metal bushing for a composite material storage tank, used to prepare the metal bushing according to any one of claims 2-7, characterized in that, Includes the following steps: S1: The metal bushing body is prepared by machining, and deformation groove one (1) and deformation groove two (2) are opened on the metal bushing body. S2: Apply a rubber coating layer to the first deformation groove (1) and the second deformation groove (2); S3: Curing the rubber coating layer; S4: Apply adhesive to the outer surface of the rubber coating layer and the arc-shaped connecting block (3); S5: Install the metal bushing body coated with adhesive into the bushing mounting hole of the composite material tank.

9. The method for preparing the metal bushing for the composite material storage tank according to claim 8, characterized in that, In step S3, the curing temperature of the rubber coating layer is room temperature. After curing the rubber coating layer, the rubber coating layer that protrudes to the outside of deformation groove one (1) and deformation groove two (2) is repaired until the outer surface of the rubber coating layer is located inside deformation groove one (1) and deformation groove two (2) and is flush with the outer surface of the arc-shaped connecting block (3).

10. The method for preparing the metal bushing for the composite material storage tank according to claim 9, characterized in that, The rubber coating layer in step S2 is applied by: pressing and curing raw rubber sheets, injecting liquid rubber through a mold, or applying it manually.

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