Axially adjustable engineered pipe segment connection and pipe segment group

Abstract

The present application relates to the technical field of pipe section connection, and particularly relates to an axial size adjustable engineering pipe section connection structure and pipe section group, which are used to solve the technical problems that the existing pipe connection structure cannot be applied to the scene with high axial size adjustment precision requirement, the processing cost is high, and the straightness cannot be guaranteed. The axial size adjustable engineering pipe section connection structure comprises an external thread joint, an internal thread joint and a ring. The outer surface of the external thread joint is provided with a first connection part, a first external gear ring part and an external thread part which are sequentially distributed along the axial direction of the external thread joint. The inner surface of the internal thread joint is provided with an internal thread part, a first internal gear ring part and a first limiting part which are sequentially distributed along the axial direction of the internal thread joint. The inner surface of the ring is provided with a second internal gear ring part. The outer surface of the rotary joint is provided with a third external gear ring part and a second connection part which are sequentially distributed along the axial direction of the rotary joint. The adjustment of the axial size of the structure is controlled based on the relative rotation tooth number of the first external gear ring part and the second external gear ring part, the precision is high, and the structure can be applied to the scene with high precision requirement.

Description

Technical Field

[0001] This invention relates to the field of pipe segment connection technology, and in particular to an engineering pipe segment connection structure and pipe segment assembly with adjustable axial dimensions. Background Technology

[0002] Pipe structures are widely used in engineering machinery and equipment. For pipe structures with requirements such as length and straightness, different sizes of pipe sections are generally connected together to achieve this.

[0003] Existing pipe sections are typically connected using flanges, welded threaded pipe fittings, or other similar structures. A flange connection involves welding two flanges to the two pipe sections to be connected, with connection holes on each flange. Bolts or other fasteners are then used to connect the two flanges through these holes. A welded threaded pipe fitting connection involves pre-machining a set of threaded pipe fittings, disassembling them, and welding each fitting to a separate pipe section. Finally, the two threaded pipe fittings are connected by threads.

[0004] The axial length of flange connections cannot be adjusted. While welded threaded pipe joints can theoretically adjust axial dimensions through rotation, the alignment of the pipe sections after adjustment is crucial, limiting adjustment to point-by-point adjustments based on the thread pitch, resulting in low precision. In other words, neither flange nor welded threaded pipe joint connections are suitable for scenarios requiring high axial dimension adjustment accuracy. Furthermore, for flange connections, welding deformation is difficult to control, necessitating post-weld machining of the flange mating surfaces and connection holes, leading to redundant processes and increased manufacturing costs. For welded threaded pipe joint connections, welding deformation compromises the straightness of the entire pipe section after connection. Summary of the Invention

[0005] To overcome the technical shortcomings of existing pipe connection structures, such as their inability to be applied to scenarios with high axial dimension adjustment accuracy, high processing costs, and inability to guarantee straightness, this invention provides an engineering pipe segment connection structure and pipe segment assembly with adjustable axial dimensions.

[0006] The axially adjustable pipe segment connection structure for engineering applications provided by this invention includes: An external threaded connector has a first connecting part, a first external gear ring part and an external thread part distributed sequentially along its axial direction on its outer circular surface. The first connecting part is used to detachably connect a pipe section. The diameter of the first external gear ring part is larger than the diameter of the external thread part and is provided with straight teeth. An internal threaded connector has an internal threaded portion, a first internal gear ring portion, and a first limiting portion arranged sequentially along its axial direction on its inner circular surface. The internal threaded portion is screwed to the external threaded portion. The first internal gear ring portion has straight teeth. The outer circular surface of the end of the internal threaded portion has a second external gear ring portion. The ring has a second internal gear ring portion on its inner circular surface, which simultaneously meshes with the first external gear ring portion and the second external gear ring portion. The rotary joint has a third external gear ring and a second connecting part arranged sequentially along its axial direction on its outer circular surface. The third external gear ring engages with the first internal gear ring and abuts against the first limiting part to achieve axial limiting. The second connecting part is used to detachably connect pipe sections.

[0007] Optionally, a first relief groove is provided between the first internal gear ring portion and the first limiting portion, and a first shoulder portion is provided extending from the third external gear ring portion. The axial dimensions of the first shoulder portion and the first relief groove are equal, and the third external gear ring portion is axially limited by abutting the first limiting portion through the first shoulder portion.

[0008] Optionally, the inner circular surface of the ring hoop is further provided with a second limiting part, and the outer circular surface of the internal threaded joint is provided with a retaining ring. A spring is pressed between the retaining ring and the second limiting part, and the spring drives the second limiting part to abut against the second external gear ring to achieve axial limiting.

[0009] Optionally, the internal threaded connector has an annular groove, and the retaining ring is placed in the annular groove.

[0010] Optionally, the retaining ring is a shaft-mounted elastic retaining ring.

[0011] Optionally, a second relief groove is provided between the second internal gear ring portion and the second limiting portion, and a second shoulder portion is provided extending from the second external gear ring portion. The axial dimensions of the second shoulder portion and the second relief groove are equal, and the second external gear ring portion is axially limited by abutting the second limiting portion through the second shoulder portion.

[0012] Optionally, both the first connecting part and the second connecting part are cylindrical segments and are used to be inserted into the pipe segment. Both the first connecting part and the second connecting part are provided with pin holes, and a pin is inserted into the pin hole and limited by a cotter pin.

[0013] Optionally, the teeth of the first outer gear ring portion, the second outer gear ring portion, the first inner gear ring portion, and the second inner gear ring portion are all trapezoidal teeth.

[0014] Optionally, both the external threaded joint and the rotary joint are shaft-type parts.

[0015] The pipe segment assembly provided by the present invention includes a first pipe segment, a second pipe segment, and the aforementioned axial dimension adjustable engineering pipe segment connection structure. The first pipe segment is detachably connected to a first connecting part, and the second pipe segment is detachably connected to a second connecting part.

[0016] The technical solution provided by this invention has the following advantages compared with the prior art: The axially adjustable pipe segment connection structure provided by this invention allows for adjustment of the axial dimension between two pipe segments through the relative rotation of an external threaded joint and an internal threaded joint. This axial dimension adjustment is controlled based on the relative rotational number of teeth of the first and second external gear rings, resulting in high precision and suitability for scenarios requiring high axial dimension adjustment accuracy. Simultaneously, this pipe segment connection structure achieves relative fixation of the internal and external threaded joints through simultaneous engagement and locking of a ring with both the first and second external gear rings. Furthermore, a rotary joint is incorporated, allowing the two pipe segments to align through rotation relative to the internal threaded joint, preventing misalignment due to small relative rotation amplitude. Additionally, this structure eliminates welding, employing a combined nested structure. This avoids difficulties in welding deformation of structural components and streamlines post-weld machining processes, effectively reducing machining difficulty, saving costs, and ensuring the straightness of the pipe segment assembly. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an assembly cross-sectional view of the pipe segment connection structure in Embodiment 1 of the present invention; Figure 2 This shows an assembled side view of the pipe segment connection structure in Embodiment 1 of the present invention; Figure 3 This diagram illustrates the structure of the external threaded connector in Embodiment 1 of the present invention. Figure 4 This diagram illustrates the structure of the internal threaded connector in Embodiment 1 of the present invention. Figure 5 This diagram illustrates the structure of the ring hoop in Embodiment 1 of the present invention. Figure 6 This diagram illustrates the structure of the rotary joint in Embodiment 1 of the present invention. Figure 7 This is a cross-sectional view of the assembly of the pipe section group in Embodiment 2 of the present invention.

[0020] In the picture: 1. External threaded connector; 11. First connecting part; 12. First external gear ring part; 13. External thread part; 2. Internal threaded connector; 21. Internal thread part; 22. First internal gear ring part; 23. First limiting part; 24. Second external gear ring part; 25. First relief groove; 26. Second shoulder part; 3. Ring clamp; 31. Second internal gear ring part; 32. Second limiting part; 33. Second relief groove; 4. Rotary joint; 41. Third external gear ring part; 42. Second connecting part; 43. First shoulder part; 5. Retaining ring; 6. Spring; 7. Pin; 8. Cotter pin; 9. Washer; 100. First pipe section; 200. Second pipe section. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0022] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Example

[0025] Reference Figures 1 to 6This embodiment provides an axially adjustable pipe section connection structure for engineering applications, including an external threaded connector 1, an internal threaded connector 2, a ring clamp 3, and a rotary connector 4. The outer surface of the external threaded connector 1 has a first connecting portion 11, a first external gear ring portion 12, and an external thread portion 13 arranged sequentially along its axial direction. The first connecting portion 11 is used for detachable connection of the pipe section. The diameter of the first external gear ring portion 12 is larger than the diameter of the external thread portion 13 and it has straight teeth. The inner surface of the internal threaded connector 2 has an internal thread portion 21, a first internal gear ring portion 22, and a first limiting portion 23 arranged sequentially along its axial direction. The internal thread portion 21 is screwed to the external thread portion 13. The first internal gear ring portion 22 has straight teeth, and the internal thread... The outer circular surface of part 21 is provided with a second external gear ring part 24; the inner circular surface of the ring 3 is provided with a second internal gear ring part 31, which simultaneously engages with the first external gear ring part 12 and the second external gear ring part 24; the outer circular surface of the rotary joint 4 is provided with a third external gear ring part 41 and a second connecting part 42 distributed sequentially along its axial direction, the third external gear ring part 41 engages with the first internal gear ring part 22, the third external gear ring part 41 abuts against the first limiting part 23 to achieve axial limiting, and the second connecting part 42 is used for detachable connection of pipe sections.

[0026] Specifically, the third external gear ring portion 41 and the first limiting portion 23 adopt an indirect abutment structure: a first relief groove 25 is provided between the first internal gear ring portion 22 and the first limiting portion 23, and the third external gear ring portion 41 extends to provide a first shoulder portion 43. The axial dimension of the first shoulder portion 43 and the first relief groove 25 are equal. The third external gear ring portion 41 abuts against the first limiting portion 23 through the first shoulder portion 43 to achieve axial limiting. Since a relief groove is required during internal gear machining, if the third external gear ring portion 41 and the first limiting portion 23 are directly abutted, a portion of the third external gear ring portion 41 will inevitably correspond to the relief groove, which would cause redundancy in the process. Therefore, in this embodiment, the first shoulder portion 43 is added so that the third external gear ring portion 41 and the first limiting portion 23 are indirectly abutted through the first shoulder portion 43, which can solve the problem of relief and ensure the necessity of the process. Of course, the third external gear ring portion 41 and the first limiting portion 23 can also abut directly.

[0027] Furthermore, the ring clamp 3 has the following improved structure: a second limiting part 32 is provided on the inner circular surface of the ring clamp 3, and a retaining ring 5 is provided on the outer circular surface of the internal threaded joint 2. A spring 6 is pressed between the retaining ring 5 and the second limiting part 32. The spring 6 drives the second limiting part 32 to abut against the second external gear ring part 24 to achieve axial limiting. The spring 6 can drive the ring clamp 3 to abut tightly against the second external gear ring part 24, preventing the ring clamp 3 from axially moving or even falling off, thereby ensuring the stability of the structural assembly.

[0028] Specifically, the retaining ring 5 adopts the following installation structure: an annular groove is provided on the internal threaded connector 2, and the retaining ring 5 is placed in the annular groove. The retaining ring 5 and the annular groove are set separately, which makes the processing more convenient and simple, and also facilitates the assembly of the spring 6. Of course, the annular groove can also be omitted, and the retaining ring 5 can be welded to the internal threaded connector 2 after the spring 6 is assembled.

[0029] More specifically, the retaining ring 5 adopts the following structure: it is a shaft-mounted elastic retaining ring. Shaft-mounted elastic retaining rings are easier to assemble. Of course, the retaining ring 5 can also adopt a two-half spliced ​​structure, as long as it can effectively limit the movement of the spring 6.

[0030] Specifically, the second external gear ring portion 24 and the second limiting portion 32 adopt an indirect abutment structure: a second relief groove 33 is provided between the second internal gear ring portion 31 and the second limiting portion 32, and a second shoulder portion 26 is provided extending from the second external gear ring portion 24. The axial dimension of the second shoulder portion 26 and the second relief groove 33 are equal. The second external gear ring portion 24 abuts against the second limiting portion 32 through the second shoulder portion 26 to achieve axial limiting. Since a relief groove is required during internal gear machining, if the second external gear ring portion 24 and the second limiting portion 32 are directly abutted, a portion of the second external gear ring portion 24 will inevitably correspond to the relief groove, which would cause redundancy in the process. Therefore, in this embodiment, a second shoulder portion 26 is added so that the second external gear ring portion 24 and the second limiting portion 32 are indirectly abutted through the second shoulder portion 26, which can solve the problem of relief and ensure the necessity of the process. Of course, the second external gear ring portion 24 and the second limiting portion 32 can also abut directly.

[0031] Specifically, the first connecting part 11 and the second connecting part 42 adopt the following detachable structure: both the first connecting part 11 and the second connecting part 42 are cylindrical segments for insertion into the pipe segment. Both the first connecting part 11 and the second connecting part 42 have pin holes, in which a pin 7 is inserted and limited by a cotter pin 8. During assembly, a through hole needs to be made on the pipe segment to be connected. The pin 7 passes through both the pin hole and the through hole and is limited by the cotter pin 8 to achieve the connection between the pipe segment connection structure and the pipe segment. This structure is simple to assemble and firmly fixed. It should be noted that, to improve straightness, it is preferable to interference fit the first connecting part 11 and the second connecting part 42 into the pipe segment. Of course, in other embodiments, the first connecting part 11 and the second connecting part 42 can also be detachably connected to the pipe segment using bolts or other methods.

[0032] More specifically, to further ensure straightness, the first limiting part 23 is designed as an annular shape, and its inner circular surface is adapted to the second connecting part 42.

[0033] More specifically, a washer 9 is provided between the cotter pin 8 and the corresponding pipe section.

[0034] Specifically, the tooth profile of the spur gears is as follows: the teeth of the first external gear ring 12, the second external gear ring 24, the first internal gear ring 22, and the second internal gear ring 31 are all trapezoidal teeth. It's easy to understand that the function of the spur gears is to mesh and engage with each other, not to perform meshing transmission in the traditional sense. Of course, spur gears can also use rectangular teeth or other common tooth profiles.

[0035] Specifically, both the external threaded connector 1 and the rotary connector 4 are shaft-type parts. Since both the external threaded connector 1 and the rotary connector 4 are used to connect pipe sections, setting them as shaft-type parts can ensure structural strength. However, the external threaded connector 1 and / or the rotary connector 4 can also be set as bushing-type parts, as long as they can be stably connected to the pipe section.

[0036] The assembly process of the axially adjustable engineering pipe segment connection structure in this embodiment is as follows: 1) Insert the rotary joint 4 into the internal threaded joint 2; 2) Screw the external threaded connector 1 into the internal threaded connector 2; 3) Assemble the ring hoop 3 into place and limit its position using the spring 6 and the retaining ring 5; 4) Assembly complete.

[0037] The axial dimension adjustment process of this structure is explained in detail below with reference to a specific product: This example demonstrates the internal transmission component of a long-handled tool used in an engineering project. The main body consists of three pipe sections, each with a required outer diameter of Φ22mm, wall thickness of 3mm, and length L=3100mm. The total length requirement is 9500±0.5mm, straightness of 1.5mm, and guide key alignment of ±0.5mm on each section. This connection structure meets the connection requirements of the three pipe sections in this example. The connection length of the pipe section connection structure meets the requirement of 200mm. The axial dimension adjustment process is as follows: 1) Determine the adjustment dimension Ls: To determine the overall length dimension Ly of the assembled product, in this example Ly = 9500.7 mm, adjust the dimension Ls as follows: Ls min=9500.7-9500.5=0.2mm, Ls max=9500.7-9499.5=1.2mm; In this example, the number of teeth Z of the first external gear ring 12 and the second external gear ring 24 is 45. Therefore, the rotation angle of the external thread connector is 8° for each tooth rotated in the circumferential direction. The pitch P of the external thread section and the internal thread section is 2.5mm. The axial dimension movement distance S is 2.5 / 360 = 0.00694mm for each 1° rotation angle of the external thread connector in the circumferential direction. Therefore, the axial dimension movement distance S1 is S × 8 = 0.055mm for each tooth rotated in the circumferential direction of the external thread connector. The adjustment dimension range in this example is 0.2mm to 1.2mm, which translates to a range of 4-21 teeth for adjusting the number of teeth in the circumferential direction of the external thread connector. In this example, the intermediate value is selected to determine the number of teeth to be adjusted as 10, that is, the adjustment dimension Ls = 10 × 0.055 = 0.55mm. 2) Ring hoop 3 tooth removal: The ring 3 is pushed to overcome the pressure of the spring 6, causing the second inner toothed ring 31 to disengage from the first outer toothed ring 12 and the second outer toothed ring 24, and to be staggered by one number of teeth, so that the ring 3 cannot be reset. 3) Adjust the number of teeth: Adjust the mating thread sections of the external threaded connector 1 and the internal threaded connector 2 so that the first external gear ring 12 rotates 10 teeth relative to the second external gear ring 24. After alignment, put the ring clamp 3 into place. 4) Disassemble the pipe section corresponding to the rotary joint 4, push the rotary joint 4 inward and rotate it until it is aligned with the external threaded joint 1, and then pull it outward to fit the third external gear ring 41 and the first internal gear ring 22 into place. 5) Connect the rotary joint 4 to the pipe section.

[0038] 6) After adjustment, the overall length dimension of 9500.15 meets the product requirements, the straightness is 1.5mm and the alignment of the guide key on each pipe section is ±0.5mm, and the final product inspection is qualified.

[0039] It should be noted that the axial adjustment and the detachability of the second connecting part 42 are an integral technical solution. If the second connecting part 42 is not detachable from the pipe section, the rotary joint 4 cannot be pushed inward after the axial dimension is adjusted, thus preventing it from rotating to realign with the first internal gear ring 22, and consequently preventing the alignment of the two pipe sections. The detachability of the first connecting part 11 is intended to form a symmetrical structure with the detachability of the second connecting part 42, ensuring the overall structural connection strength. Example

[0040] The pipe segment assembly provided by the present invention includes a first pipe segment 100, a second pipe segment 200, and an engineering pipe segment connection structure with adjustable axial dimensions as described in Embodiment 1. The first pipe segment 100 is detachably connected to the first connecting part 11, and the second pipe segment 200 is detachably connected to the second connecting part 42.

[0041] Specifically, the first pipe section 100 and the second pipe section 200 are provided with through holes corresponding to the pin holes. The pin shaft 7 passes through both the pin hole and the through hole and is limited by the cotter pin 8 to realize the connection between the pipe section and the connecting part.

[0042] The installation process of the pipe segment assembly of the present invention is as follows: 1) Assemble the external threaded connector 1 into place with the first pipe section 100 via the first connecting part 11; 2) Assemble the rotary joint 4 into place with the second pipe section 200 via the second connecting part 42; 3) Assemble a set of this pipe segment connection structure according to the assembly process of the pipe segment connection structure in Example 1 to complete the connection of the two pipe segments; 4) When it is necessary to adjust the axial dimension, the axial dimension adjustment process in Example 1 shall be followed.

[0043] The above are merely specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. An engineering pipe segment connection structure with adjustable axial dimensions, characterized in that, include: The external threaded connector (1) has a first connecting part (11), a first external gear ring part (12) and an external thread part (13) arranged sequentially along its axial direction on its outer circular surface. The first connecting part (11) is used to detachably connect pipe sections. The diameter of the first external gear ring part (12) is larger than the diameter of the external thread part (13) and is provided with straight teeth. The internal threaded connector (2) has an internal threaded part (21), a first internal gear ring part (22) and a first limiting part (23) arranged sequentially along its axial direction on its inner circular surface. The internal threaded part (21) is screwed to the external threaded part (13). The first internal gear ring part (22) is provided with straight teeth. The outer circular surface of the end of the internal threaded part (21) is provided with a second external gear ring part (24). The ring (3) has a second internal gear ring (31) on its inner circular surface. The second internal gear ring (31) engages with the first external gear ring (12) and the second external gear ring (24) at the same time. The rotary joint (4) has a third external gear ring (41) and a second connecting part (42) arranged sequentially along its axial direction on its outer circular surface. The third external gear ring (41) meshes with the first internal gear ring (22). The third external gear ring (41) abuts against the first limiting part (23) to achieve axial limiting. The second connecting part (42) is used to detachably connect pipe sections. The inner circular surface of the ring (3) is also provided with a second limiting part (32), and the outer circular surface of the internal threaded joint (2) is provided with a retaining ring (5). A spring (6) is pressed between the retaining ring (5) and the second limiting part (32). The spring (6) drives the second limiting part (32) to abut against the second external gear ring part (24) to achieve axial limiting.

2. The axially adjustable pipe segment connection structure for engineering applications according to claim 1, characterized in that, A first relief groove (25) is provided between the first internal gear ring portion (22) and the first limiting portion (23). The third external gear ring portion (41) extends and is provided with a first shoulder portion (43). The axial dimensions of the first shoulder portion (43) and the first relief groove (25) are equal. The third external gear ring portion (41) abuts against the first limiting portion (23) to achieve axial limiting.

3. The axially adjustable pipe segment connection structure for engineering applications according to claim 1, characterized in that, The internal threaded connector (2) has an annular groove, and the retaining ring (5) is placed in the annular groove.

4. The axially adjustable pipe segment connection structure for engineering applications according to claim 3, characterized in that, The retaining ring (5) is an elastic retaining ring for shafts.

5. The axially adjustable pipe segment connection structure for engineering applications according to claim 1, characterized in that, A second relief groove (33) is provided between the second internal gear ring portion (31) and the second limiting portion (32). The second external gear ring portion (24) extends and is provided with a second shoulder portion (26). The axial dimensions of the second shoulder portion (26) and the second relief groove (33) are equal. The second external gear ring portion (24) abuts against the second limiting portion (32) through the second shoulder portion (26) to achieve axial limiting.

6. The axially adjustable pipe segment connection structure for engineering applications according to claim 1, characterized in that, The first connecting part (11) and the second connecting part (42) are both cylindrical segments and are used to be inserted into the pipe segment. The first connecting part (11) and the second connecting part (42) are both provided with pin holes. A pin shaft (7) is inserted into the pin hole and is limited by a cotter pin (8).

7. The axially adjustable pipe segment connection structure for engineering applications according to any one of claims 1 to 6, characterized in that, The teeth of the first external gear ring (12), the second external gear ring (24), the first internal gear ring (22), and the second internal gear ring (31) are all trapezoidal teeth.

8. The axially adjustable pipe segment connection structure for engineering applications according to any one of claims 1 to 6, characterized in that, Both the external threaded joint (1) and the rotary joint (4) are shaft-type parts.

9. A pipe segment assembly, characterized in that, It includes a first pipe section (100), a second pipe section (200), and an engineering pipe section connection structure with adjustable axial dimensions as described in any one of claims 1 to 8, wherein the first pipe section (100) is detachably connected to the first connecting part (11), and the second pipe section (200) is detachably connected to the second connecting part (42).

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