Large-diameter seamless steel tube with unequal wall thickness

Abstract

The utility model relates to the technical field of high-pressure gas transportation equipment, in particular to a large-diameter seamless steel tube with unequal wall thickness, which is used for manufacturing a large-volume winding gas cylinder inner container and comprises a main tube, and the main tube comprises a middle section, a tube end section and a transition section positioned between the middle section and the tube end section. The pipe end section is used for forming an inner container bottle opening, the middle section is used for forming an inner container barrel, and the transition section is formed into a transition area of the inner container barrel and the inner container bottle opening. The wall thickness of the large-volume winding gas cylinder inner container made of the large-diameter seamless steel pipe with the unequal wall thicknesses can be controlled to be below 10 mm, the weight of the large-volume annular winding gas cylinder is effectively reduced, and when the inner container is formed in a spinning mode, due to the fact that the wall thicknesses of the middle section, the transition section and the pipe end section are sequentially increased, the inner container is not prone to deformation. The transition area from the inner container barrel to the inner container bottle opening does not become a weak pressure-bearing part, so that the rigidity of the inner container bottle opening part is improved, and the inner and outer threads are enough to be machined at the inner container bottle opening part.

Description

Technical Field

[0001] The utility model relates to the technical field of high-pressure gas transportation equipment, in particular to a large-diameter and unequal-wall-thickness seamless steel pipe. Background Art

[0002] With the promotion and use of hydrogen as a clean energy, large-volume high-pressure hydrogen transportation devices have developed rapidly. The pressure-bearing body of the high-pressure hydrogen transportation device is a large-volume seamless gas cylinder with a diameter of 559mm to 720mm and a length of 11m to 12m. Seamless gas cylinders are mainly divided into two categories: Type I seamless steel gas cylinders and Type II seamless gas cylinders. Type II seamless gas cylinders are steel liner circumferentially wrapped gas cylinders. Under the same pressure conditions, the wall thickness of the steel liner of the Type II seamless gas cylinder is smaller than that of the Type I seamless steel gas cylinder. The carbon fiber wrapped circumferentially on the outer surface of the steel liner has a small density and high strength, which can reduce the weight of the Type II seamless gas cylinder by 35% compared with the Type I seamless gas cylinder, effectively improving the transportation efficiency of the high-pressure hydrogen transportation device. Therefore, Type II seamless gas cylinders will become the mainstream high-pressure hydrogen transportation method in the future.

[0003] At present, the inner liner of Type II seamless gas cylinder is mainly formed by spinning chromium-molybdenum alloy steel seamless steel pipe. The wall thickness of the seamless steel pipe used is usually not less than 10mm. The reason is that there is no carbon fiber winding in the transition area from the seamless gas cylinder barrel to the head, which is a weak part under pressure. The smaller the wall thickness, the more likely it is to cause explosion failure. In addition, when the wall thickness of the seamless steel pipe is less than 10mm, the rigidity of the head is insufficient. When the inner liner of the gas cylinder is spun, the spinning part is at a high temperature of about 1100℃, which is easy to cause collapse under the pressure of the spinning wheel. The head becomes a petal shape, which is difficult to form. In addition, the thickness of the spun inner liner bottle mouth is insufficient, and the internal and external threads of the bottle mouth cannot be processed.

[0004] Therefore, in order to more effectively reduce the wall thickness of the Type II seamless gas cylinder liner, ensure the smooth spinning of the liner, ensure that the gas cylinder mouth has sufficient thickness to process the internal and external threads, and at the same time avoid forming a weak pressure-bearing part in the transition zone between the liner cylinder and the head, it is urgent to develop a thin-walled seamless steel pipe with a special structure. Utility Model Content

[0005] Based on the above problems, the purpose of the utility model is to provide a large diameter unequal wall thickness seamless steel tube so as to form a Type II seamless gas cylinder liner with a thinner wall thickness and avoid the formation of a weak pressure-bearing area in the transition zone between the liner cylinder and the head.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A large diameter unequal wall thickness seamless steel pipe, used for manufacturing large volume wound gas cylinder liner, wherein the large diameter unequal wall thickness seamless steel pipe comprises a mother pipe, the mother pipe comprises a middle section, pipe end sections located at both ends of the middle section, and a transition section located between the middle section and the pipe end sections;

[0008] The tube end section is used to form the inner liner bottle mouth, the outer diameter D of the tube end section is 500mm-720mm, the length L1 of the tube end section is D / 2+C1, C1 is 0-100mm, and the wall thickness t1 of the tube end section is not less than 10mm;

[0009] The middle section is used to form the inner liner cylinder, and the wall thickness t3 of the middle section is 5mm to 9mm;

[0010] The transition section is formed as a transition zone between the inner liner cylinder and the inner liner bottle mouth, the length of the transition section L2 = D / 4 ~ D / 3, and the wall thickness t2 of the transition section changes uniformly from t1 to t3.

[0011] Optionally, the inner liner bottle mouth and the transition zone are formed by spinning of the mother tube, and the distance between the starting position of spinning and the end face of the mother tube is L4, L4=L1+L2-C2, and C2 is 20mm-50mm.

[0012] Optionally, the tube end section is an original tube section of the mother tube, and the middle section and the transition section are processed tube sections formed by spinning or cold drawing the mother tube.

[0013] Optionally, the wall thickness t1 of the pipe end section is 10 mm to 18 mm.

[0014] Optionally, the wall thickness t3 of the middle section is 6 mm to 8 mm.

[0015] Optionally, the length L3 of the middle section is not greater than 13 m.

[0016] The beneficial effects of the utility model are as follows: the wall thickness of the large-volume wound gas cylinder liner made of the large-diameter unequal-wall-thickness seamless steel tube can be controlled to be below 10 mm, effectively reducing the weight of the large-volume circumferentially wound gas cylinder, and when the liner is spin-formed, since the wall thicknesses of the middle section, the transition section and the tube end section increase successively, the transition zone from the liner cylinder to the liner bottle mouth will not become a weak pressure-bearing portion, thereby increasing the rigidity of the liner bottle mouth and being sufficient for processing internal and external threads at the liner bottle mouth. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a seamless steel pipe with large diameter and unequal wall thickness provided by an embodiment of the utility model;

[0018] Figure 2 It is a schematic structural diagram of a large-volume wound gas cylinder liner formed by seamless steel pipes with large diameters and unequal wall thicknesses provided by an embodiment of the utility model.

[0019] In the attached figure:

[0020] 1. Mother pipe; 11. Pipe end section; 12. Transition section; 13. Middle section;

[0021] 2. Inner liner of large-volume wrapped gas cylinder; 21. Inner liner mouth; 22. Transition zone; 23. Inner liner cylinder. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0023] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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 a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0025] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0026] See also Figure 1As shown, this preferred embodiment provides a large diameter unequal wall thickness seamless steel pipe for manufacturing a large volume wound gas cylinder liner 2, the large diameter unequal wall thickness seamless steel pipe comprises a mother pipe 1, the mother pipe 1 comprises a middle section 13, pipe end sections 11 located at both ends of the middle section 13 and a transition section 12 located between the middle section 13 and the pipe end section 11, wherein:

[0027] The tube end section 11 is used to form the inner liner bottle mouth 21, the outer diameter D of the tube end section 11 is 500 mm to 720 mm, the length L1 of the tube end section 11 is D / 2+C1, C1 is 0 to 100 mm, and the wall thickness t1 of the tube end section 11 is not less than 10 mm;

[0028] The middle section 13 is used to form the inner liner cylinder 23, and the wall thickness t3 of the middle section 13 is 5 mm to 9 mm;

[0029] The transition section 12 is formed as a transition area 22 between the inner liner cylinder 23 and the inner liner bottle mouth 21. The length L2 of the transition section 12 is D / 4 to D / 3, and the wall thickness t2 of the transition section 12 changes uniformly from t1 to t3.

[0030] Therefore, the large-volume wrapped gas cylinder liner 2 made of the large-diameter unequal-wall-thickness seamless steel tube can control the wall thickness to below 10 mm, effectively reducing the weight of the large-volume circumferentially wrapped gas cylinder, and when the large-volume wrapped gas cylinder liner 2 is spin-formed, since the wall thickness dimensions of the middle section 13, the transition section 12 and the tube end section 11 increase successively, the transition zone 22 from the liner cylinder 23 to the liner bottle mouth 21 will not become a weak pressure-bearing portion, thereby increasing the rigidity of the liner bottle mouth 21 and being sufficient to process internal and external threads at the liner bottle mouth 21.

[0031] Specifically, the inner liner bottle mouth 21 and the transition zone 22 are formed by spinning of the mother tube 1, and the distance between the starting position of spinning and the end face of the mother tube 1 is L4, L4=L1+L2-C2, C2 is 20mm~50mm, and by leaving a distance C2 between the middle section 13 and the starting position of spinning, it can be ensured that the transition zone 22 has sufficient wall thickness after spinning, especially the connection between the inner liner cylinder 23 and the transition zone 22.

[0032] In particular, the pipe end section 11 is an original pipe section of the mother pipe 1 , and the middle section 13 and the transition section 12 are processed pipe sections formed by spinning or cold drawing the mother pipe 1 .

[0033] Furthermore, the wall thickness t1 of the pipe end section 11 is 10 mm to 18 mm; the wall thickness t3 of the middle section 13 is 6 mm to 8 mm; and the length L3 of the middle section 13 is not greater than 13 m.

[0034] Specific processing process:

[0035] ① Using cold drawing process to produce mother tube 1 with required diameter and thickness;

[0036] ② The middle section 13 of the mother tube 1 is processed by a strong spinning process or an improved cold drawing process and an additional machining process, so that the wall thickness t3 of the middle section 13 is further reduced;

[0037] ③ According to the forming requirements of the inner liner head after spinning, determine the length L1 of the tube end section 11 and the length L2 of the transition section 12, and make the thickness t2 of the transition section 12 change evenly to connect the middle section 13 and the tube end section 11;

[0038] ④ Determine the value of L4 and start spinning. The structure of the inner bottle mouth 21 and the transition zone 22 after molding is as follows: Figure 2 shown.

[0039] Among them, since the value of t3 is small, the requirement for weight reduction of large-volume hoop-wrapped gas cylinders can be met. At the same time, since t2 is greater than t3, the thickness of the transition zone 22 is greater than the thickness of the inner liner cylinder 23, and the transition zone 22 will not become a weak pressure-bearing part. Moreover, since t1 is greater than t3, the inner liner 2 of the large-volume wrapped gas cylinder is easy to be spin-formed. During the spinning process, the metal is continuously accumulated at the inner liner bottle mouth 21, so that the thickness of the inner liner bottle mouth 21 is sufficient to process the internal and external threads, thus meeting the processing requirements.

[0040] The above embodiments are only to illustrate the basic principles and characteristics of the utility model. The utility model is not limited by the above embodiments. Without departing from the spirit and scope of the utility model, the utility model has various changes and modifications, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. Large diameter and unequal wall thickness seamless steel pipe, used for manufacturing large volume wound gas cylinder liner (2), characterized in that: The large-diameter unequal-wall-thickness seamless steel pipe comprises a mother pipe (1), wherein the mother pipe (1) comprises a middle section (13), pipe end sections (11) located at both ends of the middle section (13), and a transition section (12) located between the middle section (13) and the pipe end sections (11). The tube end section (11) is used to form the inner liner bottle mouth (21), the outer diameter D of the tube end section (11) is 500 mm to 720 mm, the length L1 of the tube end section (11) is D / 2+C1, C1 is 0 to 100 mm, and the wall thickness t1 of the tube end section (11) is not less than 10 mm; The middle section (13) is used to form the inner liner cylinder (23), and the wall thickness t3 of the middle section (13) is 5 mm to 9 mm; The transition section (12) is formed as a transition zone (22) between the inner liner cylinder (23) and the inner liner bottle mouth (21), the length L2 of the transition section (12) is D / 4 to D / 3, and the wall thickness t2 of the transition section (12) changes uniformly from t1 to t3.

2. The large diameter and unequal wall thickness seamless steel pipe according to claim 1, characterized in that: The inner liner bottle mouth (21) and the transition zone (22) are formed by spinning of the mother tube (1), and the distance between the starting position of spinning and the end face of the mother tube (1) is L4, L4 = L1 + L2 - C2, and C2 is 20 mm to 50 mm.

3. The large diameter unequal wall thickness seamless steel pipe according to claim 1, characterized in that: The pipe end section (11) is the original pipe section of the mother pipe (1), and the middle section (13) and the transition section (12) are processed pipe sections formed by spinning or cold drawing the mother pipe (1).

4. The large diameter unequal wall thickness seamless steel pipe according to claim 1, characterized in that: The wall thickness t1 of the pipe end section (11) is 10 mm to 18 mm.

5. The large diameter unequal wall thickness seamless steel pipe according to claim 1, characterized in that: The wall thickness t3 of the middle section (13) is 6 mm to 8 mm.

6. The large diameter unequal wall thickness seamless steel pipe according to claim 1, characterized in that: The length L3 of the middle section (13) is not greater than 13m.

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