A method of manufacturing a tunnel tube for cryogenic propellants

Abstract

The present invention provides a method for manufacturing a tunnel pipe for cryogenic propellants, comprising: step S1, spraying low-temperature glue on the outer side of a cylindrical metal pipe for transmitting cryogenic propellants to form a glue coating layer; step S2, spraying a polyurethane material mixed with isocyanate (crude MDI) on the outer side of the glue coating layer to form a foam layer, wherein the polyurethane material comprises a raw ether, a branched polyester polyol, a foaming agent, monofluorodichloroethane, dibutyltin dilaurate, and pentamethyldiethylenetriamine; step S3, spraying a low-temperature glue on the outer side of the foam layer to form a sealing layer. The tunnel pipe manufactured by the method comprises a glue coating layer, a foam layer, and an insulating layer formed by the sealing layer, and is light in weight and has a simple manufacturing process.

Description

Technical Field

[0001] The invention relates to the field of tanks for space vehicles, and in particular to a method for manufacturing a tunnel tube for cryogenic propellants. Background Art

[0002] At present, in order to improve the aerodynamic layout and structural optimization of space launch vehicles, the propellant delivery pipe, i.e., the tunnel pipe, can be built into the cryogenic tank, where the tunnel pipe is a delivery pipe structure that runs through the tank. Figure 2 As shown, the prior art adopts a "double-layer casing" structure. In the "double-layer casing" structure, the outer tube is welded to the tank body, and the inner tube is connected to the outer pipeline of the tank through a flange, and the air layer between the inner tube and the outer tube is used to achieve thermal insulation of the fuel and the oxidant. The "double-layer casing" structure has a large mass and a complex production process.

[0003] In view of this, there is an urgent need to design a method for manufacturing a tunnel tube for cryogenic propellants that has a simple structure and can reduce the weight of the tunnel tube. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a method for manufacturing a tunnel tube for cryogenic propellants.

[0005] The present invention provides a method for manufacturing a tunnel tube for cryogenic propellants, comprising:

[0006] Step S1, spraying low-temperature glue on the outer side of a cylindrical metal tube used for transmitting low-temperature propellant to form a glue coating layer;

[0007] Step S2, using a polyurethane material mixed with isocyanate (crude MDI) to spray on the outside of the coating layer to form a foam layer, the polyurethane material comprising raw ether, branched polyester polyol, a foaming agent, monofluorodichloroethane, dibutyltin dilaurate, and pentamethyldiethylenetriamine;

[0008] Step S3, using low-temperature glue to spray on the outer side of the foam layer to form a sealing layer.

[0009] According to one embodiment of the present invention, step S1 includes: spraying two low-temperature glues to form the glue coating layer, first spraying low-temperature glue DW3 on the outside of the metal tube, and then spraying low-temperature glue DW1 on the outside of the low-temperature glue DW3.

[0010] According to an embodiment of the present invention, the step S1 further includes: spraying the low temperature glue DW3 to a thickness of 0.15 mm-0.25 mm, and spraying the low temperature glue DW1 to a thickness of 0.2 mm-0.25 mm.

[0011] According to an embodiment of the present invention, the step S1 further comprises: after spraying the two low-temperature adhesives, rotating the metal tube horizontally to dry the surface.

[0012] According to one embodiment of the present invention, step S2 includes: placing the polyurethane material in the first barrel of the sprayer, placing the isocyanate in the second barrel of the sprayer, mixing the solutions of the first barrel and the second barrel and spraying them to the outside of the glue layer by spiral spraying to form a foam layer.

[0013] According to one embodiment of the present invention, step S2 includes: replacing dioctyl phthalate in the foaming machine with banana oil or acetone, inserting the foaming machine feed pump into the first barrel and the second barrel, and using the polyurethane material and the isocyanate to replace banana oil or acetone for spraying.

[0014] According to one embodiment of the present invention, in step S2: the polyurethane material also includes phthalic anhydride polyester polyol.

[0015] According to one embodiment of the present invention, the step S2 comprises: spraying the foam layer to a thickness of 50 mm-60 mm.

[0016] According to an embodiment of the present invention, the step S2 comprises: after the foam layer is formed by spraying, the foam layer is processed and polished to a thickness of 20 mm to 30 mm.

[0017] According to an embodiment of the present invention, the step S3 includes: using low-temperature glue DW1 to spray on the outer side of the foam layer to form the sealing layer, and the thickness of the sealing layer is 0.4 mm-0.5 mm.

[0018] The method for manufacturing a tunnel tube for cryogenic propellants in this embodiment forms an insulating layer by spraying a rubber layer, a foam layer and a sealing layer on the outside of a single-layer metal tube, thereby overcoming the problem that the insulating layer can overcome the uneven internal stress of the material under a temperature difference environment, effectively avoiding the material cracking of the insulating layer, and solving the problem of complex tunnel tube manufacturing in the prior art. The tunnel tube reduces the overall mass of the entire space vehicle.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and illustrative and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following drawings are a part of the specification of the present invention, and illustrate exemplary embodiments of the present invention. Together with the description of the specification, the accompanying drawings are used to explain the principles of the invention.

[0021] Figure 1is a schematic diagram of a method for manufacturing a tunnel tube for cryogenic propellants according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of a storage tank under a double-layer casing according to an embodiment of the present invention;

[0023] Figure 3 It is a cross-sectional view of a tunnel tube for cryogenic propellants according to an embodiment of the present invention.

[0024] Reference numerals:

[0025] 101 - metal tube, 102 - rubber coating layer, 103 - foam layer, 104 - sealing layer. DETAILED DESCRIPTION

[0026] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are used to illustrate the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the sizes of some structural components or areas in the drawings may be enlarged for other structural components or areas to help understand the embodiments of the present invention.

[0027] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise specified, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0028] In addition, the terms "include", "comprise", "have" or any other variations thereof are intended to cover non-exclusive inclusion, so that a structure or component including a series of elements includes not only those elements, but also other mechanical elements that are not explicitly listed or inherent in the structure or component. In the absence of more restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the article or device including the elements.

[0029] Spatially related terms such as "below", "beneath", "under", "low", "above", "on", "high", etc. are used to facilitate description to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device in addition to orientations different from those shown in the figures. In addition, for example, "one element is above / below another element" can mean that the two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first", "second", etc. are also used to describe various elements, regions, parts, etc., and should not be regarded as limiting. Similar terms represent similar elements throughout the description.

[0030] For those skilled in the art, the present invention can be implemented without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present invention by showing examples of the present invention.

[0031] Figure 1 is a schematic diagram of a method for manufacturing a tunnel tube for cryogenic propellants according to an embodiment of the present invention; Figure 2 Schematic diagram of a storage tank under a double-layer casing according to an embodiment of the present invention; Figure 3 It is a cross-sectional view of a tunnel tube for cryogenic propellants according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the present invention provides a method for manufacturing a tunnel tube for cryogenic propellants, comprising:

[0033] Step S1, spraying low-temperature glue on the outer side of a cylindrical metal tube 101 for transmitting low-temperature propellant to form a glue coating layer 102;

[0034] Step S2, using a polyurethane material mixed with isocyanate (crude MDI) to spray on the outside of the adhesive layer 102 to form a foam layer 103, the polyurethane material includes raw ether, branched polyester polyol, a foaming agent, monofluorodichloroethane, dibutyltin dilaurate, and pentamethyldiethylenetriamine;

[0035] Step S3, using low-temperature glue to spray on the outer side of the foam layer 103 to form a sealing layer 104.

[0036] Specifically, the present application provides a tunnel pipe with a single-layer structure and an insulation layer of the tunnel pipe. Since the single-layer tunnel pipe is inserted into the tank, the inner side of the tunnel pipe is used to transport the propellant of the liquid oxygen material, and the temperature is about minus 180 degrees, and the outer wall of the insulation layer of the tunnel pipe is exposed to the propellant of the liquid fuel, and the temperature is about minus 160 degrees. According to the refueling requirements of the space vehicle, the insulation layer of the tunnel pipe will experience a constantly changing working environment of "normal temperature on both sides-low temperature on one side-low temperature on both sides" during use.

[0037] This method provides a thermal insulation process for a single-layer tunnel tube in a cryogenic liquid propellant. Figure 3 As shown, the outer side of the metal tube 101 is sprayed with a coating layer 102, a foam layer 103 and a sealing layer 104 in sequence to form an insulation layer, which overcomes the problem of uneven stress inside the material under a temperature difference environment, and the selected insulation layer material avoids cracking. In this embodiment, since the insulation layer of the tunnel pipe is exposed to the liquid fuel environment, on the one hand, the insulation layer is required not to dissolve with the liquid fuel, and on the other hand, the insulation layer must be effectively bonded to the wall of the metal tube 101 and cannot fall off. Among them, the sealing layer 104 can meet the requirement of not dissolving with the liquid fuel, the coating layer 102 can meet the requirement of effectively bonding with the wall of the metal tube 101, and the foam layer 103 can meet the requirement of insulation between the propellants on both sides of the tunnel tube. As one of the embodiments of this invention, before spraying the coating layer 102 in step S1, the surface of the metal tube 101 can be cleaned, and the outer surface of the metal tube 101 to be sprayed can be wiped with a white cotton cloth soaked in gasoline and alcohol in sequence until the wiping white cotton cloth does not change color.

[0038] Among them, the method of manufacturing a tunnel tube for cryogenic propellants in this application can improve the overall structural efficiency, and the insulation layer material density of the tunnel tube is small and meets the requirements of low temperature and internal pressure of liquid propellants. Compared with the traditional double-layer casing tunnel tube solution, the single-layer tunnel tube in this embodiment can reduce the weight by 50%, effectively reducing the overall mass of the space vehicle.

[0039] According to one embodiment of the present invention, step S1 includes: spraying two low-temperature glues to form a glue coating layer 102 , first spraying low-temperature glue DW3 on the outside of the metal tube 101 , and then spraying low-temperature glue DW1 on the outside of the low-temperature glue DW3 .

[0040] According to an embodiment of the present invention, step S1 further includes: spraying the low temperature glue DW3 to a thickness of 0.15 mm-0.25 mm, and spraying the low temperature glue DW1 to a thickness of 0.2 mm-0.25 mm.

[0041] According to an embodiment of the present invention, step S1 further includes: after spraying the two low-temperature adhesives, rotating the metal tube 101 horizontally to dry the surface.

[0042] Specifically, in step S1, low-temperature glue DW3 is first sprayed. Before spraying, DW3 spray glue solution needs to be prepared. DW3 spray glue solution includes three components A, B, and C. All three components are liquid. Components A and B have a higher solid content. Component C is KH550 silane coupling agent, and the diluent is acetone. The mass ratio of the three components A, B, and C is 5:1-1.1:0.2-0.4, and the ratio of diluent to component A is 1:2. The process of preparing DW3 spray glue solution is as follows: mix component A with acetone, preheat component B to 80°C, mix with component A and acetone solution after 30 minutes, and finally add component C. The mixed spray glue solution is used after aging for 15 minutes. The viscosity of the spray glue solution is measured with a 4-cup measuring tool to be less than or equal to 15s. The spray room state is adjusted to a temperature between 20-25°C and a relative humidity of ≤75%. During the spraying process, the metal tube 101 is kept rotating slowly, the rotation speed is controlled at 0.2-0.3 r / min, the spray gun is 200mm-300mm away from the surface to be sprayed, and the movement speed of the spray gun is 300-500mm / s.

[0043] After spraying, adjust the spray room state to 35-40℃, keep the metal tube 101 in a slow rotation state for 2-3h, and repeat the above process twice. Then, select the spray room temperature between 40-50℃, heat and cure the glue liquid for 36h-48h. The thickness of the glue layer 102 formed by the low-temperature glue DW3 is controlled to be 0.15mm-0.25mm.

[0044] Secondly, spray low-temperature glue DW1. The spray glue of DW1 is a two-component one, component A is a liquid, component B is a powdered solid, and the mass ratio of components A and B is 5:1. The amount of acetone added is consistent with the mass of component A. The configuration process of low-temperature glue DW1 is as follows: component B and acetone are mixed first, and then component A is added. The mixed glue solution is used after aging for 15 minutes. The viscosity of the glue solution is measured with a 4-cup measuring tool ≤15s. The spray room state is adjusted to a temperature between 20-25℃ and a relative humidity of ≤75%. Spray on the surface according to the set program. During the spraying process, keep the metal tube 101 in a slow rotation state, with a speed of 0.2-0.3r / min. During spraying, the spray gun is 200mm-300mm away from the surface to be sprayed, and the spray gun moves at a speed of 300-500mm / s. After the first spraying, keep the tunnel pipe in a slow horizontal rotation state for 2-3h to dry the surface. Next, repeat the above-mentioned process of spraying the low-temperature glue DW1 for a second spraying, and select the temperature of the spray room state between 40-45°C. After the second spraying is completed, keep the tunnel pipe in a slowly horizontally rotating state for drying for 8 hours. The total thickness of the coating layer 102 formed by the low-temperature glue DW3 and DW1 is controlled to be 0.35mm-0.5mm.

[0045] According to one embodiment of the present invention, step S2 includes: placing the polyurethane material in the first barrel of the sprayer, placing the isocyanate in the second barrel of the sprayer, mixing the solutions of the first barrel and the second barrel and spraying them to the outside of the coating layer 102 by spiral spraying to form a foam layer 103.

[0046] According to one embodiment of the present invention, step S2 includes: replacing dioctyl phthalate in the foaming machine with banana oil or acetone, inserting the foaming machine feed pump into the first barrel and the second barrel, and replacing banana oil or acetone with polyurethane material and isocyanate for spraying.

[0047] According to one embodiment of the present invention, in step S2: the polyurethane material also includes phthalic anhydride polyester polyol.

[0048] According to one embodiment of the present invention, step S2 comprises: spraying the foam layer 103 to a thickness of 50 mm-60 mm.

[0049] According to an embodiment of the present invention, step S2 includes: after the foam layer 103 is formed by spraying, the foam layer 103 is processed and polished to a thickness of 20 mm to 30 mm.

[0050] Specifically, a foaming machine and a spraying machine are required for spraying polyurethane materials. Before using the foaming machine, dioctyl phthalate needs to be used to reflux the foaming machine. This is used to maintain the foaming machine and prevent the internal parts of the foaming machine from being exposed to the air. When using the foaming machine, first use banana oil or acetone to replace the dioctyl phthalate in the foaming machine.

[0051] When the sprayer is not used for a long time, the isocyanate used as one of the foam materials will corrode the internal gaskets and rubber products of the foaming machine. If the isocyanate is stored in the foaming machine for a long time, it will affect the life of the equipment. Therefore, dioctyl phthalate is used as the liquid medium and sealed inside the sprayer.

[0052] When the sprayer is used for spraying, the dioctyl phthalate needs to be discharged and the inside of the foaming machine needs to be cleaned. Acetone and banana water are used as cleaning agents to clean the dioctyl phthalate inside the sprayer.

[0053] Before spraying to form the foam layer 103, the polyurethane material is placed in the first barrel of the sprayer, and the isocyanate is placed in the second barrel of the sprayer; the foaming machine feed pump is inserted into the first barrel and the second barrel, and the feed pump extracts the polyurethane material and isocyanate to replace the banana water or acetone in the foaming machine for spraying. The solutions of the first barrel and the second barrel are mixed and sprayed to the outside of the coating layer 102 by a spiral spraying method to form a foam layer 103 (the polyurethane material and the isocyanate react chemically to form foam). During the spraying process, the metal tube 101 is made to rotate horizontally by a rotatable tool, and the metal tube 101 is spirally sprayed by a spray gun, and the spraying is continuously carried out along the length direction of the metal tube 101 until it is completed. The polyurethane material "changes from liquid to solid" and is shaped on the surface of the metal tube 101, so that the polyurethane material is "wrapped" on the surface of the metal tube 101, reducing the possibility of material falling off and ensuring the effective combination of the foam layer 103 and the metal tube 101. Use release paper or plastic sheeting to cover the flange positions on both sides of the pipe body and the screw installation positions where the polyurethane foam layer is not required.

[0054] As one of the embodiments, in order to improve the temperature difference resistance and low temperature performance of the foam layer 103, phthalic anhydride polyester polyol is added to the white material system of the polyurethane material. The spraying method of the present application can improve the low temperature toughness of the foam pores by controlling the main material ratio, so that the foam layer 103 will not crack under the conditions of one side at room temperature and the other side at low temperature.

[0055] In this embodiment, various parameters of the foaming machine are set, wherein the pressure of the feed pump is 0.3-0.5 MPa, the solution mixing volume ratio of the first barrel and the second barrel is 1:1, and the temperature of the two barrels is set between 25-35° C. Before spraying, a test plate can be used for test spraying, and the component pressure under dynamic load state is maintained between 80-150 bar during the test spraying.

[0056] During the specific spraying process of the foam layer 103, the whole process is not allowed to be interrupted, and the metal tube 101 needs to be sprayed to the bottom with one gun when the metal tube 101 is sprayed as a whole. Formal spraying is allowed when the surface state, length and density of the metal tube 101 are normal. During the spraying process, the rotation speed of the metal tube 101 is controlled to be 3r / min, the surface temperature of the metal tube 101 is maintained ≥25°C, and the distance between the nozzle of the sprayer and the metal tube 101 is controlled to be between 800-1200mm. The spraying trajectory is spiral, and the operator needs to observe and confirm whether the fan atomization of the nozzle of the sprayer is normal, and whether there are large holes, cavities, collapsed bubbles and other phenomena on the surface of the foam layer 103. After the polyurethane material is foamed, the original spray thickness of the foam layer 103 is required to be 50mm. For the junction between spraying and masking, use a paper cutter to cut the foam layer 103 into a 45° groove, and the groove forming work should be carried out within 3 hours after the foaming is completed.

[0057] Among them, since the density of the formed foam layer 103 is uneven, the density of the foam layer 103 on the side close to the metal tube 101 is relatively high, and the density of the foam layer 103 on the side far from the metal tube 101 is relatively low, it is necessary to use an angle grinder and a scouring pad to grind the surface of the foam layer 103 with a relatively low density. The first round of grinding processes the surface thickness of the foam layer 103 to 25 mm, and the second round of grinding processes the surface thickness to 20 mm.

[0058] According to an embodiment of the present invention, step S3 includes: using low-temperature glue DW1 to spray on the outer side of the foam layer 103 to form a sealing layer 104, and the thickness of the sealing layer 104 is 0.4 mm-0.5 mm.

[0059] Specifically, since there will be polyurethane powder residue on the surface of the polyurethane material after polishing, in order to ensure that the residual powder does not fall into the inside of the tank body, the polished polyurethane surface needs to be sealed once. In step S3, the sealing layer 104 is formed by spraying the low-temperature glue DW1. DW1 low-temperature glue is a two-component system, component A is a liquid with a high solid content, component B is a powdered solid, and the diluent is acetone. The mass ratio of components A and B is 5:1, and the mass of acetone added is consistent with that of component A. The configuration method of the spraying glue is: first, component B is mixed with acetone, and then component A is added. The mixed liquid is matured for 15 minutes before use. The viscosity of the spraying glue is measured with a 4-cup measuring tool to be less than or equal to 15s. Spray on the surface of the foam layer 103 according to the set program, the spray gun is between 200mm-300mm away from the surface to be sprayed, and the movement speed of the spray gun is maintained at 300-500mm / s. The thickness of the adhesive layer of the sealing layer 104DW1 is controlled to be between 0.4 mm and 0.5 mm.

[0060] In some optional embodiments, the sealing layer 104 can be treated by spraying the low-temperature glue DW1. The spraying method will make the solvent volatilize easily in the air, resulting in poor bonding between the residual powder after grinding and the sealing layer 104, so a brushing method can be selected. When the brushing method is adopted, acetone or banana water solvent can be added to the glue liquid of the low-temperature glue DW1. Since acetone and banana water themselves have a corrosive effect on the polyurethane material, after the glue liquid is brushed on the surface of the polyurethane material, the resin will penetrate into the surface of the polyurethane material, and the corrosive effect of the solvent on the polyurethane material is used to ensure that the sealing layer 104 has a good bonding with the polyurethane material, thereby forming a sealing layer 104 with good bonding.

[0061] The above are only preferred embodiments of the present invention and are 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 in the protection scope of the present invention.

Claims

1. A method of manufacturing a tunnel tube for cryogenic propellants, It is characterized in that include: Step S1, spraying low-temperature glue on the outer side of a cylindrical metal tube for transmitting low-temperature propellant to form a glue coating layer; spraying two low-temperature glues to form the glue coating layer, first spraying low-temperature glue DW3 on the outer side of the metal tube, and then spraying low-temperature glue DW1 on the outer side of the low-temperature glue DW3; The thickness of the low temperature glue DW3 is sprayed to 0.15mm-0.25mm, and the thickness of the low temperature glue DW1 is sprayed to 0.2mm-0.25mm; Step S2, using a polyurethane material mixed with isocyanate to spray on the outside of the adhesive layer to form a foam layer, the polyurethane material comprising raw ether, branched polyester polyol, a foaming agent, monofluorodichloroethane, dibutyltin dilaurate, and pentamethyldiethylenetriamine; Step S3, using low-temperature glue to spray on the outer side of the foam layer to form a sealing layer.

2. The method for manufacturing a tunnel tube for cryogenic propellants according to claim 1, It is characterized in that The step S1 further comprises: After spraying the two low-temperature adhesives, the metal pipe is rotated horizontally to dry the surface.

3. The method for manufacturing a tunnel tube for cryogenic propellants according to claim 1, It is characterized in that The step S2 comprises: The polyurethane material is placed in the first barrel of the sprayer, and the isocyanate is placed in the second barrel of the sprayer. The solutions in the first barrel and the second barrel are mixed and sprayed onto the outside of the adhesive layer by a spiral spraying method to form a foam layer.

4. The method of manufacturing a tunnel tube for cryogenic propellants according to claim 3, It is characterized in that The step S2 comprises: Banana oil or acetone is used to replace dioctyl phthalate in the foaming machine, the foaming machine feed pump is inserted into the first barrel and the second barrel, and the polyurethane material and the isocyanate are used to replace banana oil or acetone for spraying.

5. The method of manufacturing a tunnel tube for cryogenic propellants according to claim 3, It is characterized in that In step S2: The polyurethane material also includes phthalic anhydride polyester polyol.

6. The method of manufacturing a tunnel tube for cryogenic propellants according to claim 3, It is characterized in that The step S2 comprises: The foam layer is sprayed to a thickness of 50 mm to 60 mm.

7. The method of manufacturing a tunnel tube for cryogenic propellants according to claim 6, It is characterized in that The step S2 comprises: After the foam layer is formed by spraying, the foam layer is processed and polished to a thickness of 20mm-30mm.

8. The method of manufacturing a tunnel tube for cryogenic propellants according to claim 1, It is characterized in that The step S3 comprises: The sealing layer is formed by spraying low-temperature glue DW1 on the outer side of the foam layer, and the thickness of the sealing layer is 0.4mm-0.5mm.

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