Device and method for eliminating residual stress of whole bottom of storage tank of spaceflight carrier rocket

Abstract

The invention discloses a device and a method for eliminating residual stress of a whole bottom of a storage tank of a spaceflight carrier rocket. The device is characterized by comprising a liquid nitrogen conveying system (2), a whole rocket tank bottom (3), a water cooling system (4), a whole bottom flange ring fixing block (5) and a convex mold (6), the whole bottom flange ring fixing block (5) is used for fixing the whole rocket tank bottom (3) to the convex mold (6), and the liquid nitrogen conveying system (2) is used for introducing liquid nitrogen into the outer molded surface of the whole rocket tank bottom (3) according to a set value. And the water cooling system (4) is used for introducing liquid water into different positions of the inner molded surface of the whole bottom (3) of the rocket storage tank through water filling channels according to requirements, and establishing a temperature gradient from inside to outside, so that tank bottom cooling and liquid-solid phase change of water are realized, bulging is generated, and internal stress is eliminated. According to the device and the method, the box bottom can be locally cooled and bulged according to needs, and the purpose of meeting the size precision and performance requirements of the whole bottom is achieved.

Description

Technical Field

[0001] The invention belongs to the field of large-scale metal curved surface processing in the field of aerospace, and specifically relates to a device and method for eliminating residual stress in the bottom of a space launch vehicle tank. Background Art

[0002] At present, as my country's new generation of launch vehicles develops towards integration, large-scale, lightweight, and high reliability, integrated forming has become an inevitable trend in the development of advanced manufacturing technology in the aerospace field. As the core key component of the tank, the integral tank bottom can effectively reduce the weight of the rocket body and improve the rocket's carrying capacity.

[0003] Residual stress is inevitable in the forming process of the whole bottom parts. Stress relaxation during service will cause deformation of the parts, greatly affecting the dimensional accuracy of the components and reducing their yield strength and service stability. Therefore, a method to reduce and eliminate the residual stress of the whole bottom is urgently needed to achieve the purpose of meeting the dimensional accuracy and performance requirements of the whole bottom.

[0004] Specifically, after the rocket tank bottom 3 is filled with liquid and stretched, serious residual stress exists in various areas. The elimination of residual stress and product shape retention cannot be ignored. The device of the present invention is based on the analysis of the stress of fluid high-pressure forming of the rocket tank bottom 3. It proposes an effective way to introduce cooling water and liquid nitrogen into the inner and outer surfaces of the bottom respectively to eliminate the residual stress of the tank bottom and promote product shape retention. It has important engineering application value. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method and device for eliminating residual stress in the bottom of a space launch vehicle tank, so as to solve the problem that residual stress is generated after forming large-sized integral curved surface thin-walled components, affecting the service effect and stability.

[0006] In order to solve the above technical problems, the present invention provides a device for eliminating residual stress in the bottom of a space launch vehicle tank, which is characterized by comprising a liquid nitrogen delivery system 2, a rocket tank bottom 3, a water cooling system 4, a bottom flange ring fixing block 5, and a convex mold 6. The bottom flange ring fixing block 5 is used to fix the rocket tank bottom 3 on the convex mold 6, and the liquid nitrogen delivery system 2 is used to introduce liquid nitrogen into the outer surface of the rocket tank bottom 3 according to a set value. The water cooling system 4 is used to introduce liquid water into different positions of the inner surface of the rocket tank bottom 3 through a water filling channel according to demand settings, so as to establish a temperature gradient from the inside to the outside, thereby realizing cooling of the tank bottom and liquid-to-solid phase change of water. The tank bottom shrinks when cooled, and expands in volume when the liquid water cools the solid phase, thereby achieving the effect of bulging the tank bottom and eliminating internal stress.

[0007] Furthermore, the water cooling system 4 is provided with latitudinal and longitudinal water filling channels on the inner surface of the entire bottom 3 of the rocket tank by means of the design of the convex mold 6. The latitudinal and longitudinal water filling channels are arranged to be independent of each other and can be opened separately to adjust the latitudinal and longitudinal residual stresses of the tank bottom separately according to the need to eliminate residual stress in different areas on the tank bottom.

[0008] Furthermore, the liquid nitrogen delivery system 2 is provided with a liquid nitrogen injection chamber for adding liquid nitrogen into the system.

[0009] Furthermore, the material of the entire bottom 3 of the rocket tank is 2219 high-strength aluminum alloy, 2A14 high-strength aluminum alloy, or 2195 aluminum-lithium alloy.

[0010] Furthermore, the whole bottom flange ring fixing block 5 is evenly arranged around the whole bottom 3 parts of the rocket tank avoiding the water filling channel, and is designed as a universal or special device according to the flange ring size as needed.

[0011] Furthermore, the entire bottom 3 of the rocket tank is replaced by a closed or semi-closed structural member, a part formed from a sheet material, a component obtained by additive manufacturing, forging, casting or machining.

[0012] The present invention also provides a method for eliminating residual stress by adjusting the bottom of a space launch vehicle tank, which is characterized in that the method uses the above-mentioned device for eliminating residual stress by adjusting the bottom of a space launch vehicle tank, and comprises the following steps:

[0013] S1 Pre-assembly positioning: Place the rocket tank bottom 3 parts on the convex mold 6 using the bottom flange ring fixing block 5 to fix the position;

[0014] S2: Cooling water is introduced: the water cooling system 4 introduces cooling water to the inner surface of the rocket tank bottom 3 while maintaining the position after the pre-installation.

[0015] S3: Liquid nitrogen is introduced into the outer surface of the rocket tank bottom 3 through the liquid nitrogen delivery system 2, and the volume of liquid nitrogen is 1 to 1.25 times that of the cooling water;

[0016] S4 local cooling and bulging: The cooling body of the rocket tank bottom 3 shrinks and the volume expands due to the water solid phase change, causing the local area of ​​the rocket tank bottom 3 parts to deform. When the predetermined residual stress elimination effect is achieved, the bulging ends and the rocket tank bottom 3 is removed.

[0017] Furthermore, in the pre-installation positioning S1, the fixing blocks 5 of the entire bottom flange ring are evenly arranged.

[0018] Furthermore, when cooling water is introduced into S2, the water cooling system 4 opens water filling channels at different longitudinal and latitudinal positions according to the residual stress regulation requirements.

[0019] Furthermore, when liquid nitrogen is introduced into S3, the volume of the liquid nitrogen is 1 to 1.25 times that of the cooling water introduced.

[0020] The present invention can locally cool and bulge the bottom of the box as required, so as to meet the requirements of the dimensional accuracy and performance of the entire bottom. The present invention has the following advantages:

[0021] 1 The present invention proposes a method of realizing local thermal deformation by means of thermal expansion and contraction. The thermal stress of the alternating cycle of hot and cold accelerates the release of macroscopic residual stress, effectively eliminates the internal stress of the material, and improves the dimensional accuracy and service stability of the whole bottom part product;

[0022] 2. The heat of the water in the bottom of the box is transferred from the bottom of the box to the liquid nitrogen, thereby achieving box bottom cooling and liquid-solid phase change of water, avoiding the problems of performance degradation caused by the traditional introduction of heat to increase the aging speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that for the sake of clarity and ease of description, the drawings are not necessarily drawn to scale.

[0024] Figure 1 A schematic diagram of a device for eliminating residual stress in a launch vehicle tank bottom trimming according to the present invention;

[0025] Figure 2 It is a schematic diagram of the latitudinal and longitudinal water filling channels of the entire bottom of the storage tank of the present invention.

[0026] Markings in the figure: 1-liquid nitrogen filling cavity, 2-liquid nitrogen delivery system, 3-rocket tank bottom, 4-water cooling system, 5-bottom flange ring fixing block, 6-convex mold. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 The schematic diagram of the device for eliminating residual stress in the bottom of the launch vehicle tank of the present invention is shown in FIG. Figure 1 As shown, in one embodiment, the overall structure of the device for eliminating residual stress in the bottom of a space launch vehicle tank of the present invention includes a liquid nitrogen delivery system 2, a rocket tank bottom 3, a water cooling system 4, a bottom flange ring fixing block 5, and a convex mold 6.

[0030] The bottom flange ring fixing block 5 is used to fix the rocket tank bottom 3 on the convex mold 6, the water cooling system 4 is used to introduce liquid water into different positions of the inner surface of the rocket tank bottom 3 according to the demand settings, and the liquid nitrogen delivery system 2 is used to introduce liquid nitrogen into the outer surface of the rocket tank bottom 3 according to the set value to establish a temperature gradient from the inside to the outside. The heat of the water on the inner surface of the rocket tank bottom 3 is transferred from the rocket tank bottom 3 to the liquid nitrogen, thereby realizing the cooling of the rocket tank bottom 3 and the liquid-solid phase change of the water. The bottom of the box shrinks when it is cooled, and the volume expands when the liquid water cools and changes to the solid phase, thereby achieving the effect of bulging the bottom of the box and eliminating internal stress.

[0031] The liquid nitrogen delivery system 2 is provided with a liquid nitrogen flushing chamber 1 for adding liquid nitrogen into the system.

[0032] The thermal stress of the hot and cold alternating cycle accelerates the release of macroscopic residual stress. The bulging effect caused by the contraction of the cooling body at the bottom of the box and the volume expansion of the water solid phase change is also used to eliminate residual stress.

[0033] The rocket tank bottom 3 may be made of 2219 high-strength aluminum alloy, 2A14 high-strength aluminum alloy, or 2195 aluminum-lithium alloy. The rocket tank bottom 3 may be a closed or semi-closed structural part, a part formed from a sheet, or a component obtained by additive manufacturing, forging, casting, or machining.

[0034] Figure 2 This is a schematic diagram of the water filling channels in the latitudinal and longitudinal directions of the entire bottom of the storage tank of the present invention. Figure 2 As shown, the water cooling system 4 of the present invention is provided with latitudinal and longitudinal water filling channels on the inner surface of the rocket tank bottom 3 by means of the design of the convex mold 6. Figure 1 The water cooling system 4 is shown as a continuous state. Figure 2 The water filling channels in are interconnected. The above is only for illustration. In fact, the design can realize the function of separate regulation. The latitudinal and longitudinal water filling channels are independent of each other and can be opened separately. According to the need to eliminate residual stress in different areas on the bottom of the box, the latitudinal and longitudinal residual stresses of the rocket tank bottom 3 are separately regulated. According to the need to eliminate residual stress in different areas on the rocket tank bottom 3, water filling channels at different longitudinal and latitudinal positions are set to be opened. The rocket tank bottom 3 is locally cooled and expanded as needed, thereby realizing the separate regulation of the latitudinal and longitudinal residual stresses of the rocket tank bottom 3 and achieving local cooling and expansion effects.

[0035] The whole bottom flange ring fixing block 5 is evenly arranged around the whole bottom 3 parts of the rocket tank avoiding the water filling channel, and can be designed as a universal or special device according to the flange ring size as needed.

[0036] A method for eliminating residual stress in the bottom of a space launch vehicle tank corresponding to the above device of the present invention comprises the following steps:

[0037] S1 Pre-installation positioning: The rocket tank bottom 3 parts are placed on the convex mold 6 using the bottom flange ring fixing blocks 5, and the bottom flange ring fixing blocks 5 are evenly arranged to fix the position;

[0038] S2: keep the position after pre-installation unchanged, open the water filling channels of the water cooling system 4 at different longitudinal and latitudinal positions according to the residual stress control requirements, and introduce cooling water into the inner surface of the rocket tank bottom 3;

[0039] S3: Liquid nitrogen is introduced into the outer surface of the rocket tank bottom 3 through the liquid nitrogen delivery system 2, and the volume is 1 to 1.25 times that of the cooling water;

[0040] S4 local cooling and bulging: The cooling body of the rocket tank bottom 3 shrinks and the volume expands due to the water solid phase change, causing the local area of ​​the rocket tank bottom 3 parts to deform. When the predetermined residual stress elimination effect is achieved, the bulging ends and the rocket tank bottom 3 is removed.

[0041] When there are different local areas on the bottom 3 of the rocket tank that need to eliminate residual stress, the water cooling system 4 is set to open the longitudinal and latitudinal water filling channels in different areas to execute the process of steps S1 to S4, thereby achieving cooling and expansion of different areas.

[0042] Therefore, the method for eliminating residual stress in the bottom of the space launch vehicle tank adopts the method of thermal expansion and contraction to achieve local thermal deformation, and the thermal stress of the hot and cold alternating cycle accelerates the release of macro residual stress, effectively eliminates the internal stress of the material, and improves the dimensional accuracy and service stability of the bottom component product.

[0043] The liquid nitrogen and cooling water can eliminate residual stress on the entire bottom of the storage tank. The liquid nitrogen absorbs heat to reduce the temperature of the cooling water, and expands in volume after solidifying into ice, which is beneficial to the expansion and shape preservation of the entire bottom of the storage tank. At the same time, the heat of the water in the bottom of the tank is transferred from the bottom of the tank to the liquid nitrogen, thereby realizing the cooling of the bottom of the tank and the liquid-solid phase change of the water, avoiding the problems of performance degradation caused by the traditional method of introducing heat to increase the aging speed.

[0044] Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention. The contents not described in detail in the specification of the present invention belong to the known technology of professional and technical personnel in this field.

Claims

1. A device for eliminating residual stress in the bottom of a space launch vehicle tank, characterized in that: The invention comprises a liquid nitrogen delivery system (2), a rocket tank bottom (3), a water cooling system (4), a bottom flange fixing block (5), and a convex mold (6). The bottom flange fixing block (5) is used to fix the rocket tank bottom (3) on the convex mold (6). The liquid nitrogen delivery system (2) is used to introduce liquid nitrogen into the outer surface of the rocket tank bottom (3) according to a set value. The water cooling system (4) is used to introduce liquid water into different positions of the inner surface of the rocket tank bottom (3) through a water filling channel according to demand settings, so as to establish a temperature gradient from the inside to the outside, thereby realizing cooling of the tank bottom and liquid-to-solid phase change of water. The tank bottom shrinks when cooled, and expands in volume when the liquid water cools and undergoes solid phase change, thereby achieving the effect of bulging the tank bottom and eliminating internal stress.

2. A device for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 1, characterized in that: The water cooling system (4) is provided with latitudinal and longitudinal water filling channels on the inner surface of the entire bottom (3) of the rocket tank by means of the design of a convex mold (6). The latitudinal and longitudinal water filling channels are arranged to be independent of each other and can be opened separately to adjust the latitudinal and longitudinal residual stresses of the tank bottom separately according to the need to eliminate residual stress in different areas on the tank bottom.

3. A device for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 1, characterized in that: The liquid nitrogen delivery system (2) is provided with a liquid nitrogen injection chamber (1) for adding liquid nitrogen into the system.

4. A device for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 1, characterized in that: The material of the rocket tank bottom (3) is 2219 high-strength aluminum alloy, 2A14 high-strength aluminum alloy, or 2195 aluminum-lithium alloy.

5. The device for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 1, characterized in that: The bottom flange fixing blocks (5) are evenly arranged around the rocket tank bottom (3) parts, avoiding the water filling channel, and are designed as general or special devices according to the flange size as required.

6. The device for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 1, characterized in that: The entire bottom (3) of the rocket tank is replaced by a closed or semi-closed structural member, a part formed from a sheet material, or a member obtained by additive manufacturing, forging, casting or machining.

7. A method for eliminating residual stress in the bottom of a space launch vehicle tank, characterized in that: The device for eliminating residual stress in the bottom of a space launch vehicle tank according to any one of claims 1 to 6 comprises the following steps: S1 Pre-installation positioning: The rocket tank bottom (3) parts are placed on the convex mold (6) using the bottom flange ring fixing block (5) to fix the position; S2: Cooling water is introduced: the water cooling system (4) introduces cooling water into the inner surface of the rocket tank bottom (3) while maintaining the position after the pre-installation positioning unchanged; S3: Liquid nitrogen is introduced into the outer surface of the rocket tank bottom (3) through the liquid nitrogen delivery system (2), and the volume of liquid nitrogen is 1 to 1.25 times that of the cooling water introduced; S4 local cooling and bulging: The cooling body of the rocket tank bottom (3) shrinks and the volume expands due to the water solid phase change, causing deformation of the local area of ​​the rocket tank bottom (3) part. When the predetermined residual stress elimination effect is achieved, the bulging is completed and the rocket tank bottom (3) is removed.

8. A method for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 7, characterized in that: In the S1 pre-installation positioning, the entire bottom flange ring fixing blocks (5) are evenly arranged.

9. A method for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 7, characterized in that: When cooling water is introduced into S2, the water cooling system (4) opens water filling channels at different longitudinal and latitudinal positions according to the residual stress control requirements.

10. A method for eliminating residual stress in the bottom of a space launch vehicle tank as claimed in claim 7, characterized in that: Liquid nitrogen is introduced into S3, and the volume of liquid nitrogen is 1 to 1.25 times that of cooling water.

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