Axial low-pressure wave forming device and method for aluminum alloy corrugated pipe

Abstract

The invention provides an axial low-pressure corrugation forming device and method for an aluminum alloy corrugated pipe. The axial low-pressure corrugation forming device comprises an inner supporting pipe structure and an outer mold structure, the inner supporting pipe structure is sleeved with a to-be-machined pipe, and the outer mold structure is arranged on the outer side of the to-be-machined pipe; the inner supporting pipe structure comprises a movable mold pipe, a static mold pipe and a high-pressure self-sealing expansion ring; the static mold pipe is fixedly arranged on one side of the movable mold pipe, and the movable mold pipe changes the distance between the movable mold pipe and the static mold pipe through the pushing assembly. The high-pressure self-sealing expansion rings are symmetrically arranged on the movable mold pipe and the static mold pipe respectively; the high-pressure self-sealing expansion ring, the movable die pipe, the static die pipe and the pipe to be machined form an air chamber, the side, away from the movable die pipe, of the static die pipe is communicated with compressed air, and one side of the static die pipe is communicated with the compressed air. The method has the beneficial effects that low-internal-pressure arcing and axial feeding forming are adopted for corrugated pipe forming, the final reduction rate of the wall thickness at the wave crest after corrugation forming is smaller than 7%, the index requirement that the reduction rate of the aluminum alloy corrugated pipe is smaller than 10% is met, and the requirement that the wave spacing is 130 + / -1 mm is met.

Description

Technical Field

[0001] The invention belongs to the field of bellows preparation, and in particular relates to an axial low-pressure shaping and internal high-pressure wave forming device and method for an aluminum alloy bellows. Background Art

[0002] As a key component of the rocket, the fuel tank tunnel tube (corrugated tube) of the launch vehicle has high standard requirements for product dimensional accuracy, material thinning rate, and surface quality. The traditional fuel tank tunnel tube production process includes flat plate stretching and corrugation, tube rolling, longitudinal seam welding, circumferential seam welding and other processes, with a long production cycle and high cost. The skill level of the personnel has a great influence on the quality of the weld. At the same time, the rocket fuel tank tunnel tube is made of aluminum alloy, and the material elongation is low. The current mature corrugated tube manufacturing process is extremely difficult to meet the production needs of the fuel tank tunnel tube. Summary of the invention

[0003] In view of this, the present invention aims to provide an axial low-pressure corrugation device and method for an aluminum alloy bellows to solve at least one technical problem in the background technology.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows: An axial low-pressure corrugation device for an aluminum alloy corrugated pipe comprises an inner support pipe structure and an outer mold structure, wherein a pipe sleeve to be processed is arranged outside the inner support pipe structure, and the outer mold structure is arranged outside the pipe to be processed; The inner support tube structure includes a movable mold tube, a static mold tube, and a high-pressure self-sealing expansion ring; the static mold tube is fixedly arranged on one side of the movable mold tube, and the movable mold tube changes the distance between the movable mold tube and the static mold tube by pushing the assembly; The high-pressure self-sealing expansion ring is symmetrically arranged on the moving mold tube and the static mold tube; the high-pressure self-sealing expansion ring, the moving mold tube, the static mold tube and the tube to be processed form an air chamber, the static mold tube is connected to the compressed gas on the side away from the moving mold tube, and the side of the static mold tube is connected to the compressed gas.

[0005] Furthermore, the movable mold tube and the static mold tube are both columnar.

[0006] Furthermore, the outer diameters of the movable mold tube and the static mold tube are both 3-5 mm smaller than the diameter of the tube to be processed.

[0007] Furthermore, flexible isolation gaskets are provided on both sides of the movable mold tube and the static mold tube; The diameter of the flexible isolation gasket is 0.5~1mm smaller than the inner diameter of the pipe to be processed.

[0008] Furthermore, the interior of the high-pressure self-sealing expansion ring is hollow, and the sealing ring is filled with high-pressure gas when the high-pressure self-sealing expansion ring is connected to the external high-pressure gas for operation; The material of the high-pressure self-sealing expansion ring is elastic material such as rubber. When not inflated, the outer diameter of the high-pressure self-sealing expansion ring is the same as the outer diameter of the flexible isolation gasket. After inflation, the outer diameter of the high-pressure self-sealing expansion ring corresponds to the inner diameter of the processing tube. The pressure of the gas filled in the high-pressure self-sealing expansion ring is ≤8MPa, and the pressure of the gas filled in the high-pressure self-sealing expansion ring is at least 0.3MPa higher than the pressure of the air chamber.

[0009] Further, the outer mold structure includes a first outer mold and a second outer mold; The first outer mold and the second outer mold both include an upper outer mold and a lower outer mold, the upper outer mold and the lower outer mold are pushed by a hydraulic cylinder, and the upper outer mold and the lower outer mold form a forming cavity for the tube to be processed; The upper outer mold and the lower outer mold each include two or more mold halves. During forming, the upper outer mold and the lower outer mold are pushed and pressed onto the prefabricated tube blank by a hydraulic cylinder, and the pressing position of the upper outer mold and the lower outer mold should correspond to the high-pressure self-sealing expansion ring.

[0010] A method for preparing high-pressure corrugated pipe corrugated pipe internal corrugated pipe, using the above-mentioned low-pressure corrugated pipe axial corrugated pipe device, characterized in that it comprises the following steps: S1: preparing a prefabricated tube; S2: The prefabricated tube is placed on the inner support tube structure, and the prefabricated tube moves from the movable mold tube to the static mold tube; the distance between the movable mold tube and the static mold tube is adjusted according to the corrugated forming size. S3: Compress the outer mold structure; fill the high-pressure self-sealing expansion ring with compressed air; fill the air chamber with compressed gas; S4: The moving mold tube is axially fed toward the static mold tube for final forming, and the feeding is stopped when the upper outer film and the lower outer film are attached; S5: Depressurize the air chamber, and depressurize the high-pressure self-sealing expansion ring after the air chamber pressure is completely unloaded; S6: After the pressure of the high-pressure self-sealing expansion ring is unloaded, the outer mold on the movable mold tube side is retracted, and the movable mold tube moves in the opposite direction of the static mold tube. After moving to the required distance, the outer mold structure presses the prefabricated tube again; At the same time, the outer mold structure on the stationary mold tube side is retracted, and the outer mold structure on the movable mold tube side is synchronously fed to complete the tube blank feeding, and then the outer mold on the stationary mold tube side is pressed again; S7: Repeat S3 to S6 described in step 2 to perform corrugation until all corrugations of the tube blank are completed.

[0011] Furthermore, the preparation of the prefabricated tube in step S1 is performed by forming the tube in accordance with the drawing requirements by coiling and welding the sheet material, or directly using a thin-walled extruded tube and a spinning tube.

[0012] Furthermore, in step S3, the pressure of the gas filled into the high pressure self-sealing expansion ring is ≤8MPa, and the pressure of the gas filled into the high pressure self-sealing expansion ring is at least 0.3MPa higher than the pressure of the air chamber; In step S3, the air chamber is filled with compressed gas, and the compressed gas should be ≤7MPa.

[0013] Further, until all corrugations of the tube are completed, the peak height of the tube after forming meets mm requirement, the corrugation spacing meets the requirement of 130±1mm, and the final wall thickness thinning rate is less than 7%, meeting the thinning rate indicator requirement of less than 10%.

[0014] Compared with the prior art, the axial low-pressure corrugation device and method of an aluminum alloy bellows described in the present invention has the following advantages: 1) The present invention provides a method and tooling for high-pressure corrugation and surface quality protection of rocket fuel tank bellows. The invention realizes low-thinning corrugation of tunnel pipes by internal high-pressure pre-forming and homogenization of deformation area thinning, and realizes low-thinning of tunnel pipe corrugations through axial feeding final forming, which completely avoids cracking due to excessive thinning rate, and solves technical problems such as insufficient elongation of aluminum alloy bellows and easy cracking of wave forming. The bellows are formed by low internal pressure arc starting and axial feed forming. After corrugation forming, the final thinning rate of the wall thickness at the wave peak is less than 7%, which meets the thinning rate index requirement of less than 10% for aluminum alloy bellows and the wave spacing requirement of 130±1mm. 2) The present invention realizes flexible isolation and flexible high-pressure sealing between the tunnel tube and the forming tooling through reasonable design of the forming tooling, completely avoiding problems such as rigid contact between the tube blank and the tooling and scratches on the inner wall of the tube, and finally realizes efficient and high-quality forming of the rocket fuel tank tunnel tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0016] Figure 1 It is a schematic diagram of the process of comparative example 1 in the prior art of the present invention; Figure 2 This is a schematic diagram of forming a flat-plate coiled tube welded prefabricated tube blank according to Example 1 of the present invention; Figure 3 This is a physical picture of the flat plate coiled pipe welded prefabricated pipe blank described in Example 1 of the present invention; Figure 4 It is a schematic diagram of the prefabricated tube blank formed by spinning and thinning a thick-walled tube as described in Example 1 of the present invention, which is formed by spinning and thinning a thick-walled seamless tube to a required wall thickness; Figure 5 The thick-walled tube spinning thinning prefabricated tube blank described in Example 1 of the present invention; FIG6 is a schematic diagram of an axial low-pressure corrugation device for an aluminum alloy bellows according to Example 1 of the present invention; FIG. 7 is a schematic diagram of the covering position of the spray quenching furnace described in Example 1 of the present invention.

[0017] Description of reference numerals: 1. Tube to be processed; 2. Moving mold tube; 3. Static mold tube; 4. Upper outer mold; 5. High-pressure self-sealing expansion ring; 6. Lower outer mold; 7. Flexible isolation gasket. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0020] like Figure 1 For fuel tank tunnel pipes, there are high requirements for dimensional accuracy, material thinning rate, and surface quality after product forming. The current mature corrugated pipe manufacturing process has a large local thinning rate at the wave crest, and the inner wall is in rigid contact with the equipment or tooling, which is very easy to be scratched, and it is difficult to meet product requirements; fuel tank tunnel pipes are all made of aluminum alloy, and the material elongation is low (15~20%). The wave forming process using simple bulging, extrusion, etc., the thinning rate at the wave crest exceeds 15%, which has reached the material elongation limit. The wave forming process is very easy to crack and does not meet the forming process conditions. The use of sheet stretching to form waves, the coiled tube welding process has insufficient production efficiency, and the longitudinal weld of the product cannot be avoided, which greatly restricts the product reliability.

[0021] Step 1: The tube billet is prefabricated by coiling and welding the sheet into a tube billet that meets the requirements of the drawing, or directly using thin-walled extruded tube billets and spinning tube billets. Figure 2 The prefabricated tube blank is made by directly cutting the plate with the required thickness and then rolling and welding it into the prefabricated tube blank.

[0022] The high-pressure corrugated tube internal wave forming device comprises an inner support tube structure and an outer mold structure. The inner support tube structure is columnar, and the prefabricated tube blank is sleeved on the inner support tube structure. The inner support tube structure is composed of two half molds, and the two half molds form a corrugated tube forming cavity.

[0023] The inner support tube structure is composed of a movable mold tube 2 (the inner support tube on the left side of the figure) and a static mold tube 3 (the inner support tube on the right side of the figure). The outer diameters of the movable mold tube 2 and the static mold tube 3 should be 3-5 mm smaller than the diameter of the prefabricated tube blank to prevent the tube blank from having a rigid contact with the inner support tube, causing scratches on the inner wall of the tube blank. Two sets of flexible isolation washers 7 are attached to both the moving mold tube 2 and the static mold tube 3. The flexible isolation washers 7 isolate the prefabricated tube from direct rigid contact with the inner support tube. The diameter of the flexible isolation washers 7 is slightly smaller than the inner diameter of the prefabricated tube by 0.5~1mm, ensuring that a certain gap is maintained between the prefabricated tube and the inner support tube after loading, so as to facilitate the loading of the prefabricated tube and the unloading of the product after forming. At the same time, the hardness of the material of the flexible isolation washers 7 should be slightly lower than the hardness of the aluminum alloy prefabricated tube and have self-lubricating properties to ensure smooth movement of the tube during the forming process;

[0024] The side of the static mold tube 3 away from the dynamic mold tube 2 is connected to compressed gas and is provided with a fixing rod (the fixing rod is not drawn in the figure), by which the static mold tube 3 is fixed to one side of the dynamic mold tube 2. The fixing rod is arranged inside the static mold tube 3 and does not affect the movement of the tube 1 to be processed.

[0025] A push rod (not shown) is provided on the side of the movable mold tube 2 away from the static mold tube 3. The push rod is connected to the hydraulic lever and is arranged inside the movable mold tube 2 without affecting the movement of the tube 1 to be processed.

[0026] The inner support tube is composed of a dynamic die group and a static die group, each of which is attached with a group of high-pressure self-sealing expansion rings 5. The high-pressure self-sealing expansion ring 5 is hollow in design and is made of elastic materials such as rubber. The high-pressure self-sealing expansion ring 5 is connected to external high-pressure gas (the connecting pipe is not drawn). The diameter of the high-pressure self-sealing expansion ring 5 is consistent with the flexible isolation gasket 7. When working, the high-pressure self-sealing expansion ring 5 is filled with high-pressure gas. The high-pressure self-sealing expansion ring 5 expands and forms a sealed air chamber together with the inner support tube and the outer mold tube. The air chamber is also connected to the external high-pressure gas. The high-pressure self-sealing design can completely avoid rigid contact between the sealing device and the tube blank, and the forming process can effectively improve the surface quality of the product.

[0027] The outer mold structure consists of an upper outer mold 4 and a lower outer mold 6. Each half mold is divided into two or more mold halves. During forming, the mold halves are pushed and pressed onto the prefabricated tube by a hydraulic cylinder. The pressing position should correspond to the high-pressure self-sealing expansion ring 5 to prevent the high-pressure self-sealing expansion ring 5 from rupture due to inflation.

[0028] Step 2: Corrugation Forming (1) The prefabricated tube is placed on the inner support tube, and the feeding direction of the prefabricated tube moves from the movable die group to the static die group.

[0029] (2) Adjust the distance between the dynamic die set and the static die set according to the corrugated forming size, and press the outer die; (3) Further fill the high-pressure self-sealing ring with compressed air. The filled gas pressure should be ≤8MPa and exceed the air chamber inflation pressure to 0.3MPa higher than the air chamber pressure; (4) Corrugated preforming: Compressed gas is filled into the air chamber. In order to control the thinning rate of the formed tube wall, the compressed gas should be ≤7MPa and less than the gas pressure determined by the wall thickness and material strength of the prefabricated tube. After the compressed air is filled, the tube blank is partially bulged and deformed, and the maximum thinning rate of deformation is less than 5%; (5) Axial material filling and corrugation final forming: The axial material filling and corrugation final forming is performed by feeding the moving die set of the inner support tube toward the static die set. When the two halves of the outer die are fitted together, the feeding is stopped. After corrugation, the material thinning rate increases by about 1%. (6) Pressure relief: First, the air chamber is depressurized, and after the air chamber pressure is completely unloaded, the high-pressure self-sealing expansion ring 5 is depressurized; (7) After the pressure of the high-pressure self-sealing expansion ring 5 is unloaded, the outer mold on the movable mold tube 2 side is retracted, and the movable mold tube 2 is moved in the opposite direction of the static mold tube 3. After it moves to the required distance, the outer mold structure presses the prefabricated tube blank again; at the same time, the outer mold structure on the static mold tube 3 side is retracted, and the outer mold structure on the movable mold tube 2 side is synchronously fed to complete the tube blank feeding, and then the outer mold on the static mold tube side is pressed again; (8) Repeat steps (3) to (7) described in step 2 to perform corrugation forming until all corrugations of the tube blank are formed. After forming, the peak height of the tube blank meets the mm requirement, the corrugation spacing meets the 130±1 mm requirement, and the final wall thickness reduction rate is less than 7%, meeting the thinning rate index requirement of less than 10%.

[0030] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An axial low-pressure corrugated bellows device for aluminum alloy bellows, characterized in that: It includes an inner support pipe structure and an outer mold structure, the pipe to be processed is sleeved outside the inner support pipe structure, and the outer mold structure is arranged outside the pipe to be processed; The inner support tube structure includes a movable mold tube, a static mold tube, and a high-pressure self-sealing expansion ring; the static mold tube is fixedly arranged on one side of the movable mold tube, and the movable mold tube changes the distance between the movable mold tube and the static mold tube by pushing the assembly; The high-pressure self-sealing expansion ring is symmetrically arranged on the moving mold tube and the static mold tube; the high-pressure self-sealing expansion ring, the moving mold tube, the static mold tube and the tube to be processed form an air chamber, and the static mold tube is connected to the compressed gas on the side away from the moving mold tube, and the compressed gas supplies air to the air chamber.

2. The axial low-pressure corrugation device for an aluminum alloy bellows according to claim 1 is characterized in that: Both the moving mold tube and the static mold tube are columnar.

3. The axial low-pressure corrugation device for an aluminum alloy bellows according to claim 1 is characterized in that: The outer diameters of the moving mold tube and the static mold tube are both 3~5mm smaller than the diameter of the tube to be processed.

4. The axial low-pressure corrugation device for an aluminum alloy bellows according to claim 1 is characterized in that: Flexible isolation washers are provided on both sides of the moving mold tube and the static mold tube; The diameter of the flexible isolation gasket is 0.5~1mm smaller than the inner diameter of the pipe to be processed.

5. The axial low-pressure corrugation device for an aluminum alloy bellows according to claim 1, characterized in that: The interior of the high-pressure self-sealing expansion ring is hollow. When the high-pressure self-sealing expansion ring is connected to the external high-pressure gas, the sealing ring is filled with high-pressure gas; The material of the high-pressure self-sealing expansion ring is elastic material such as rubber. When not inflated, the outer diameter of the high-pressure self-sealing expansion ring is the same as the outer diameter of the flexible isolation gasket. After inflation, the outer diameter of the high-pressure self-sealing expansion ring corresponds to the inner diameter of the processing tube. The pressure of the gas filled in the high-pressure self-sealing expansion ring is ≤8MPa, and the pressure of the gas filled in the high-pressure self-sealing expansion ring is at least 0.3MPa higher than the pressure of the air chamber.

6. The axial low-pressure corrugation device for an aluminum alloy bellows according to claim 1, characterized in that: The outer mold structure includes a first outer mold and a second outer mold; The first outer mold and the second outer mold both include an upper outer mold and a lower outer mold, the upper outer mold and the lower outer mold are pushed by a hydraulic cylinder, and the upper outer mold and the lower outer mold form a forming cavity for the tube to be processed; The upper outer mold and the lower outer mold each include two or more mold halves. During forming, the upper outer mold and the lower outer mold are pushed and pressed onto the prefabricated tube blank by a hydraulic cylinder, and the pressing position of the upper outer mold and the lower outer mold should correspond to the high-pressure self-sealing expansion ring.

7. A method for axial low-pressure corrugation of an aluminum alloy bellows, using the axial low-pressure corrugation device for an aluminum alloy bellows according to any one of claims 1 to 6, characterized in that: The steps include: S1: preparing a prefabricated tube; S2: The prefabricated tube is placed on the inner support tube structure, and the prefabricated tube is moved from the movable mold tube to the static mold tube; the distance between the movable mold tube and the static mold tube is adjusted according to the corrugated forming size; S3: Compress the outer mold structure; fill the high-pressure self-sealing expansion ring with compressed air; fill the air chamber with compressed gas; S4: The moving mold tube is axially fed toward the static mold tube for final forming, and the feeding is stopped when the upper outer film and the lower outer film are attached; S5: Depressurize the air chamber, and depressurize the high-pressure self-sealing expansion ring after the air chamber pressure is completely unloaded; S6: After the pressure of the high-pressure self-sealing expansion ring is unloaded, the outer mold on the movable mold tube side is retracted, and the movable mold tube moves in the opposite direction of the static mold tube. After moving to the required distance, the outer mold structure presses the prefabricated tube again; At the same time, the outer mold structure on the stationary mold tube side is retracted, and the outer mold structure on the movable mold tube side is synchronously fed to complete the tube blank feeding, and then the outer mold on the stationary mold tube side is pressed again; S7: Repeat S3 to S6 described in step 2 to perform corrugation until all corrugations of the tube blank are completed.

8. The method for preparing high pressure wave in a corrugated tube according to claim 7, characterized in that: The preparation of the prefabricated tube in step S1 is performed by coiling and welding the sheet material into a tube that meets the requirements of the drawing, or directly using a thin-walled extruded tube and a spinning tube.

9. The method for preparing high pressure wave in a corrugated tube according to claim 7, characterized in that: In step S3, the pressure of the gas filled into the high pressure self-sealing expansion ring is ≤8MPa, and the pressure of the gas filled into the high pressure self-sealing expansion ring is at least 0.3MPa higher than the pressure of the air chamber; In step S3, the air chamber is filled with compressed gas, and the compressed gas should be ≤7MPa.

10. The method for preparing high pressure wave in a corrugated tube according to claim 7, characterized in that: Until all corrugations are formed on the tube billet, and the peak height of the tube billet after forming meets the requirements mm requirement, the corrugation spacing meets the requirement of 130±1mm, and the final wall thickness thinning rate is less than 7%, meeting the thinning rate indicator requirement of less than 10%.

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