Method and device for assembling a PE double-wall pipe

Abstract

The application discloses a kind of PE double-layer pipeline assembly method and device, for inserting inner tube into outer tube along horizontal direction, wherein, the outer wall bottom of inner tube is equipped with a plurality of support members spaced along the axis direction of inner tube, and the lower side of inner tube is equipped with monitoring cable sequentially passing through each support member along the axis direction of inner tube;Assembly device includes: rack;Inner tube fixing unit is installed in rack, and inner tube fixing unit is used to fix the first end of inner tube;Traction device is installed in rack, and traction device is used to pull outer tube sleeved on the second end of inner tube, so that outer tube is fed to the first end of inner tube;Lifting mechanism includes moving support and lifting unit, moving support is assembled to be able to be fixedly connected with the end of outer tube close to moving support, lifting unit is installed in moving support, and lifting unit is suspended below inner tube.

Description

Technical Field

[0001] This invention relates to the field of double-layer pipe assembly technology, specifically to a method and apparatus for assembling PE double-layer pipes. Background Technology

[0002] In municipal water supply and drainage, chemical media transportation, and oil and gas field gathering and transportation pipelines, PE double-layer pipes with online monitoring functions are increasingly widely used. This type of double-layer pipe consists of an inner pipe and an outer pipe nested together. The inner pipe is used to transport the medium, and multiple support members are installed at axial intervals along the bottom of the outer wall of the inner pipe to ensure the coaxiality of the outer side of the inner pipe. At the same time, a monitoring cable extending axially is inserted in the annular gap to monitor the pipeline's operating parameters such as leakage, deformation, and temperature in real time.

[0003] Currently, the assembly of PE double-layer pipes mostly adopts a horizontal pipe-threading process, where one end of the inner pipe is fixed, and the outer pipe is horizontally fitted onto the outside of the inner pipe using a traction device. During actual assembly, due to its own weight, the suspended inner pipe will undergo downward deflection, causing the bottom surface of the support component at the bottom of the inner pipe to be lower than the bottom surface of the inner wall of the outer pipe. When the outer pipe is fed inward, the end face of the outer pipe will directly and rigidly scrape and jam against the support component, causing not only wear and detachment of the support component, but also easily squeezing and scraping the monitoring cable within the annular gap. In severe cases, it can even lead to chipping and breakage of the outer pipe end, resulting in extremely low assembly quality and efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for assembling PE double-layer pipes to overcome the above-mentioned shortcomings in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An assembly device for a double-layer PE pipe is provided for inserting an inner pipe into an outer pipe in a horizontal direction. The bottom of the outer wall of the inner pipe is provided with multiple support members spaced apart along the axial direction of the inner pipe. A monitoring cable is provided below the inner pipe, passing sequentially through each of the support members along the axial direction of the inner pipe. The assembly device includes: frame; An inner tube fixing unit is installed on the frame, and the inner tube fixing unit is used to fix the first end of the inner tube; A traction device is installed on the frame. The traction device is used to pull the outer tube sleeved on the second end of the inner tube so that the outer tube is fed towards the first end of the inner tube. The lifting mechanism includes a movable support and a lifting unit. The movable support is assembled to be fixedly connected to one end of the outer tube near the movable support. The lifting unit is mounted on the movable support and suspended below the inner tube. The lifting unit is configured such that, during the feeding process of the outer tube towards the first end of the inner tube, the lifting unit can lift the support member from a first height to a second height before the support member enters the outer tube, and hold the support member at the second height until at least one end of the support member enters the outer tube; when the support member is at the first height, the bottom surface of the support member is lower than the bottom surface of the inner wall of the outer tube, and when the support member is at the second height, the bottom surface of the support member is higher than the bottom surface of the inner wall of the outer tube.

[0006] Preferably, the lifting unit is provided with a clearance portion for avoiding the monitoring cable, the clearance portion being configured to form a clearance channel for the monitoring cable between the two supports to pass through when the lifting unit is located between the two supports.

[0007] Preferably, the lifting unit includes a roller, which is rotatably connected to the movable bracket. The axis of the roller is horizontally arranged and perpendicular to the axes of the inner tube and the outer tube. The radius of the roller is greater than the thickness of the support member. Along the axial direction of the inner tube and the outer tube, the distance between the vertex of the roller surface of the idler roller and the end face of the outer tube near the movable support is less than the length of the support member.

[0008] Preferably, in the axial direction of the idler roller, the diameter of the middle part of the idler roller is smaller than the diameter of both ends of the idler roller, and the clearance part includes an annular groove provided on the roller surface of the idler roller.

[0009] Preferably, the traction device includes a winch and a traction rope, the winch is mounted on the frame, one end of the traction rope is connected to the winch, and the other end of the traction rope is connected to the movable support.

[0010] Preferably, it also includes a friction-reducing unit for supporting the outer tube below to reduce the feed resistance of the outer tube.

[0011] Preferably, the friction reduction unit includes a plurality of support frames for supporting the bottom of the outer tube and spaced apart along the axial direction of the outer tube. The outer tube is non-connected to the support frames. The support frames are provided with limiting portions for preventing the outer tube from displacing relative to the support frames in a second direction, the second direction being a horizontal direction perpendicular to the axial direction of the outer tube. The bottom of the support frames is provided with support wheels.

[0012] Preferably, the bottom of the movable support is provided with a roller, and only one roller is provided in the axial direction of the outer tube.

[0013] Preferably, it also includes an outer tube fixing unit; The outer tube fixing unit includes a lower support fixedly mounted on a movable bracket, and an upper clamping seat is detachably connected to the lower support by bolts. The outer tube fixing unit has the same structure as the inner tube fixing unit; The lower support of the inner tube fixing unit is fixedly mounted on the frame; Each of the upper clamping bases and lower support bases can be detachably equipped with an adjusting half-ring to accommodate different pipe diameters of the inner and outer tubes.

[0014] A method for assembling a double-layer PE pipe, implemented using the aforementioned assembly device, includes the following steps: S1 Two-section inner tube preparation: Place the two sections of inner tube until the color marking lines on the tube body are aligned with each other. Mark the installation points of the support components on the outer wall of the inner tube. The installation points are set at equal intervals, and the installation points are reserved from the tube end for the working distance of the inner tube hot melt welding. S2 Installation of one of the inner tube support components: Align the radial groove of the support component with the color mark line at the bottom of the inner tube, and use PE glue to attach multiple support components to the marked installation points on the inner tube; The support is provided with radial grooves and axial grooves. The monitoring cable is placed in the radial groove of each support in a straight line, and the support is bound to the inner tube by passing through the axial groove of the support with PET strapping. S3 Inner Tube Welding: The inner tube with the support and monitoring cable already installed is hot-melted and welded to another inner tube using a fully automatic hot-melt welding machine; Remove the protruding adhesive strips caused by hot melt welding at the welding position, inspect the welding quality at the welding position, and install the support and monitoring cable on the other section of the inner tube using the same method as in step S2. S4 outer tube pre-installed electrofusion straight connector: Mark the insertion depth of the electrofusion straight connector at the outer tube end, and fit the electrofusion straight connector onto the end of the outer tube according to the mark; S5 Inner and Outer Tube Sleeving Installation: The inner tube and support are inserted into the outer tube using an assembly device; S6 Outer Pipe Electrofusion Welding: After the inner and outer pipes are connected and installed, the outer pipe is electrofused through the electrofusion straight tube pre-installed in S4, and the welding position is inspected. The protruding rubber strip removed in step S3 is folded and visually inspected. If the protruding rubber strip is cracked, it is cut off and re-welded. If the protruding rubber strip is not cracked, the hot melt weld joint is then inspected by a 360° surround scan using a dedicated non-destructive testing device. In step S6, the electrofusion welding position is directly inspected by a dedicated non-destructive testing device using a 360° circumferential scanning method.

[0015] In the above technical solution, the assembly method and apparatus for PE double-layer pipes provided by the present invention have the following beneficial effects: 1. Utilizing a follow-up lifting structure, the support at the bottom of the inner pipe is raised and maintained at a certain height before the outer pipe is fed in and the support enters the outer pipe opening. This effectively solves the problem of the support being too low due to the inner pipe's own weight, preventing the support from scraping or getting stuck between the support and the outer pipe opening, ensuring smooth pipe assembly. Simultaneously, an annular clearance groove in the middle of the roller effectively avoids the pipe monitoring cable, preventing it from being squeezed or worn during the roller's rotation. Furthermore, the roller uses a rolling contact lifting method, resulting in low frictional resistance and preventing scratches on the support and the outer wall of the inner pipe, significantly improving the assembly qualification rate and efficiency of PE double-layer pipes.

[0016] 2. The mobile support has only a single roller at its bottom, and the outer pipe overlaps with the support frame, making it highly adaptable to complex working conditions such as uneven ground and varying elevations. The single roller support design eliminates multi-point limiting constraints, allowing the mobile support to adaptively adjust its posture and angle according to changes in ground flatness. This effectively avoids structural jamming and feed obstruction caused by differences in ground surface area. Simultaneously, the free overlap structure between the outer pipe and the support frame eliminates rigid constraints, allowing for the release of vertical offsets and minor deformation stresses generated during pipe assembly. This reduces compressive and bending stresses within the pipe, preventing deformation of the PE outer pipe due to stress. This significantly lowers the equipment's requirements for site flatness, ensuring smooth and stable feeding of the outer pipe throughout the entire process.

[0017] 3. The step-by-step process layout of "pre-installation of support components and monitoring cables in a single section of inner pipe - hot-melt welding of inner pipe - installation of accessories for another section of pipe" effectively avoids interference problems caused by the protruding support components and monitoring cables on the alignment, clamping, and hot-melt propulsion operations of the fully automatic hot-melt welding machine, compared to the traditional process of pre-installing two sections of inner pipe before welding. At the same time, it avoids damage to the monitoring cables due to pulling and squeezing during the welding process. When the weld fails the inspection and needs to be cut and reworked, this process layout can effectively control the impact of rework on the pipe end spacing, prevent the installation spacing of the support components near the welding end of the two sections of inner pipe from becoming disordered, and also avoid the already laid monitoring cables from shifting, bending, and loosening, ensuring the accuracy of the support component layout and the accuracy of pipeline leakage monitoring.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0019] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a schematic diagram of the assembly device structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the movable support and frame provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the movable support structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the rack structure provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the connection between the inner tube and the outer tube provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the lower support base and upper clamping base structure provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the support frame structure provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the support structure provided in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Frame; 11. Traction device; 2. Moving support; 21. Roller; 22. Idler roller; 3. Lower support seat; 31. Upper clamping seat; 32. Adjusting half ring; 4. Support frame; 41. Limiting part; 42. Support wheel. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0024] Please see Figure 1-8 An assembly device for a double-layer PE pipe is provided for inserting an inner pipe into an outer pipe in a horizontal direction. The bottom of the outer wall of the inner pipe is provided with multiple support members spaced apart along the axial direction of the inner pipe. A monitoring cable is provided below the inner pipe, passing sequentially through each support member along the axial direction of the inner pipe. The assembly device includes: Rack 1; An inner tube fixing unit is installed on frame 1. The inner tube fixing unit is used to fix the first end of the inner tube. Traction device 11 is installed on frame 1. Traction device 11 is used to pull the outer tube sleeved on the second end of the inner tube so that the outer tube is fed to the first end of the inner tube. The lifting mechanism includes a movable support 2 and a lifting unit. The movable support 2 is assembled to be fixedly connected to one end of the outer tube near the movable support 2. The lifting unit is installed on the movable support 2 and is suspended below the inner tube. The lifting unit is configured such that, during the feeding process from the outer tube to the first end of the inner tube, the lifting unit can lift the support member from a first height to a second height before the support member enters the outer tube, and hold the support member at the second height until at least one end of the support member enters the outer tube; when the support member is at the first height, the bottom surface of the support member is lower than the bottom surface of the inner wall of the outer tube, and when the support member is at the second height, the bottom surface of the support member is higher than the bottom surface of the inner wall of the outer tube.

[0025] During assembly, the first end of the inner tube is fixed by the inner tube fixing unit, and the end of the outer tube is fixedly connected to the moving bracket 2. The outer tube is initially fitted outside the second end of the inner tube. The traction device 11 drives the outer tube to feed towards the fixed end of the inner tube, and the moving bracket 2 and the lifting unit move synchronously with the outer tube. When the opening of the outer tube approaches a certain support, the lifting unit lifts the support from the first height to the second height, so that the bottom surface of the support is higher than the bottom surface of the inner wall of the outer tube; then the opening of the outer tube continues to feed, and the support smoothly enters the interior of the outer tube at the second height, avoiding scraping against the end face of the opening. After a part of the support has entered the outer tube, the lifting unit continues to move with the outer tube and detaches from the support. The inner tube falls back under the action of gravity, and the support overlaps the bottom of the inner wall of the outer tube. During the continuous feeding of the outer tube, the lifting unit moves synchronously with the outer tube, and performs the "lift-hold-detach" action for each support along the way in sequence, realizing the smooth insertion of the support throughout the entire stroke.

[0026] The lifting unit moves with the outer pipe and automatically adapts to multiple spaced supports on the inner pipe, eliminating the need for individual adjustments and significantly improving the assembly efficiency of long pipelines. By pre-lifting the supports, rigid scraping and jamming between the supports and the outer pipe openings are fundamentally avoided, protecting the support and pipe opening structures and improving the assembly qualification rate.

[0027] The lifting unit is provided with a clearance section for avoiding monitoring cables. The clearance section is configured to form a clearance channel for the monitoring cables between the two supports when the lifting unit is located between the two supports.

[0028] The lifting unit is equipped with a clearance section, which is a groove-type channel structure arranged along the axial direction of the lifting unit. When the lifting unit is positioned between two adjacent support members, the clearance section corresponds precisely to the monitoring cable between the two support members, forming a clearance channel for the monitoring cable to pass through. The supporting surface of the lifting unit does not contact the monitoring cable. During the feeding process with the outer tube, the lifting unit only contacts the bottom surface of the support member through the supporting surfaces on both sides to achieve lifting. When the monitoring cable is located between two support members, it falls into the channel formed by the clearance section, without being squeezed or rubbed against the structure of the lifting unit. This avoids the lifting unit squeezing or wearing the monitoring cable, ensuring the integrity of the monitoring cable.

[0029] The lifting unit includes a roller 22, which is rotatably connected to the movable support 2. The axis of the roller 22 is set horizontally and perpendicular to the axis of the inner tube and the outer tube. The radius of the roller 22 is greater than the thickness of the support member. Along the axial direction of the inner and outer tubes, the distance between the top of the roller surface of the idler roller 22 and the end face of the outer tube near the movable support 2 is less than the length of the support member.

[0030] During the lifting process, the roller surface of the idler roller 22 rolls in contact with the support member and rotates with the feed of the outer tube, changing sliding friction into rolling friction. The rolling idler roller 22 has the advantages of low frictional resistance, low traction load, smooth lifting action, and is not easy to scratch the surface of the support member. The radius of the idler roller 22 is larger than the vertical thickness of the support member. When the support member moves with the feed of the inner tube, after the idler roller 22 contacts the support member, it rotates on its own to lift the support member. If the radius of the idler roller 22 is equal to or smaller than the thickness of the support member, the support member will abut against the idler roller 22, causing the idler roller 22 to be unable to rotate and unable to lift the support member, thus hindering the feed movement of the support member.

[0031] In other embodiments of the present invention, the lifting unit is not limited to the rotating roller 22 structure in the above embodiments. It can also adopt a fixed low-friction support component, such as a polytetrafluoroethylene (PTFE) slider, a nylon slider, or a ceramic pad. The fixed support component has a smooth support surface, which is inclined and slides and guides the bottom surface of the support component to lift the support component from a first height to a second height during the outer tube feeding process. The support surface can also be provided with a friction-reducing coating or embedded balls to further reduce sliding friction resistance. In addition, the lifting unit can also be configured as a liftable support plate, a pneumatic or hydraulically driven lifting block, a flexible suspension claw, an electromagnetic adsorption lifting component, or multiple independent lifting roller groups arranged at intervals along the inner tube axis.

[0032] Any lifting unit that can move synchronously with the movable support 2 and raise and maintain the support at the second height before it enters the outer tube is an equivalent alternative to the lifting unit of the present invention and should fall within the protection scope of the present invention.

[0033] Meanwhile, since the distance from the top of the roller surface to the end face of the outer tube is less than the length of the support, when the front end of the support enters the outer tube, the rear end of the support is still attached to the idler roller 22 and remains in an elevated state until a part of the support enters the outer tube and then detaches from the idler roller 22. This ensures that the support remains elevated throughout the tube entry process, avoiding the risk of the support falling and getting stuck at the tube opening and improving the smoothness of the support entering the outer tube.

[0034] Along the axial direction of the idler roller 22, the diameter of the middle part of the idler roller 22 is smaller than the diameter of both ends of the idler roller 22, and the clearance part includes an annular groove provided on the roller surface of the idler roller 22.

[0035] The idler roller 22 is thinner in the middle and thicker at both ends along its own axis, with the diameter in the middle being smaller than the diameter at both ends; the annular groove in the middle of the roller surface of the idler roller 22 is the avoidance part, and the monitoring cable can be accommodated in the annular groove without contacting the roller surface.

[0036] The coarse-diameter roller surfaces at both ends of the idler roller 22 contact the bottom surfaces on both sides of the support to achieve stable lifting; the annular groove in the middle corresponds to the laying position of the monitoring cable. When the idler roller 22 is located between the two support components, the cable is located in the annular groove and has no contact with the roller surface, thus avoiding the rolling of the idler roller 22 and causing squeezing and wear.

[0037] The rollers on both sides can play a certain role in centering and limiting the support, preventing the support from shifting laterally and improving the coaxiality of the tube.

[0038] The traction device 11 includes a winch and a traction rope. The winch is mounted on the frame 1, one end of the traction rope is connected to the winch, and the other end of the traction rope is connected to the movable support 2.

[0039] During assembly, the winch winds up the traction rope, which pulls the movable support 2 axially toward the inner tube fixing unit, thereby driving the outer tube to feed synchronously and achieving stable assembly of the inner and outer tubes.

[0040] In other embodiments of the present invention, the traction device 11 may adopt a sprocket and chain traction mechanism. A transmission chain is arranged on the frame 1 along the axial direction of the pipe. The chain is fixedly connected to the movable support 2. The sprocket is driven by a motor to rotate forward and backward, thereby driving the chain to move in a cycle, and thus driving the movable support 2 and the outer pipe to be continuously fed. As long as the movable support 2 can drive the outer pipe to move and complete the insertion and assembly with the inner pipe, it is an equivalent alternative to the traction device 11 of the present invention and should fall within the protection scope of the present invention.

[0041] It also includes a friction-reducing unit for supporting the outer tube below to reduce the feeding resistance of the outer tube. During the feeding process of the outer tube, most of its weight is borne by the friction-reducing unit. The rolling support greatly reduces the frictional resistance during the feeding of the outer tube and reduces the load on the traction device 11.

[0042] The friction reduction unit includes multiple support frames 4 for supporting the bottom of the outer tube and spaced apart along the axial direction of the outer tube. The outer tube is non-connected to the support frames 4. The support frames 4 are provided with limiting parts 41 for preventing the outer tube from displacing relative to the support frames 4 in a second direction. The second direction is a horizontal direction perpendicular to the axial direction of the outer tube. The bottom of the support frame 4 is provided with support wheels 42.

[0043] The outer tube is attached to the support frame 4 and is fed by the support wheel 42 to reduce frictional resistance. The limiting parts 41 on both sides limit the outer tube laterally to prevent the outer tube from swaying left and right during the feeding process. That is, it prevents the outer tube from moving relative to the support frame 4 in the second direction, ensuring the coaxiality of the outer tube and the inner tube, and avoiding jamming or increased resistance in the assembly process of the inner and outer tubes due to misalignment.

[0044] The bottom of the movable support 2 is provided with a roller 21, and only one roller 21 is provided in the axial direction of the outer tube.

[0045] The mobile support 2 has only one roller 21 at its bottom, and the outer pipe is simply placed on the support frame 4 without being fixedly connected. When the ground at the construction site is uneven, the single roller 21 structure allows the mobile support 2 to adapt to the undulations of the ground and make fine adjustments to its angle and posture, without causing rigid support or jamming due to differences in ground level. The outer pipe, relying on the overlapping support structure, can flexibly and adaptively make fine adjustments according to the uneven ground and the vertical displacement of the pipe itself. This can release the squeezing and bending stress generated during the assembly process, avoid the outer pipe being rigidly constrained and forcibly limited, and effectively prevent the pipe from deforming or being damaged. At the same time, it ensures smooth and stable feeding of the outer pipe, greatly improving the adaptability of the device to complex and uneven construction sites.

[0046] It also includes an outer tube fixing unit; the outer tube fixing unit includes a lower support seat 3 fixedly mounted on the movable support 2, and an upper clamping seat 31 is detachably connected to the lower support seat 3 by bolts; the outer tube fixing unit has the same structure as the inner tube fixing unit; the lower support seat 3 of the inner tube fixing unit is fixedly mounted on the frame 1; each upper clamping seat 31 and the lower support seat 3 can be detachably equipped with an adjusting half ring 32 to adapt to different pipe diameters of the inner and outer tubes. At the same time, the traction rope on the winch can be connected to the upper clamping seat 31 to drive the movable support to move.

[0047] During assembly, place the pipe end on the adjusting half ring 32 of the lower support 3, fasten the upper clamping seat 31 and tighten the bolts to clamp and fix the pipe end. By replacing the adjusting half ring 32 with different inner diameters, it can be adapted to inner and outer pipes of different diameters. It can be adapted to PE pipes of various diameters without replacing the entire clamping seat, thus improving the applicability.

[0048] The working principle of the PE double-layer pipe assembly device of this invention: One end of the inner tube is fixed between the upper clamping seat 31 and the lower support seat 3 on the frame 1, and one end of the outer tube is fixed between the upper clamping seat 31 and the lower support seat 3 on the movable bracket 2. Then, the traction rope of the traction device 11 is connected to the upper clamping seat 31 on the movable bracket 2, and the traction rope is wound up by a winch to pull the movable bracket 2 and the outer tube to move. During the process of the outer tube moving and assembling with the inner tube, when the support passes the position of the idler roller 22, the idler roller 22 contacts the support and rotates itself as the movable bracket 2 and the outer tube move, lifting the support and the inner tube upward, so that when the support enters the outer tube, it will not scrape or jam with the end face of the outer tube. After the support enters the outer tube, the idler roller 22 disengages from the support and lowers the support and the inner tube. Then, the movable bracket 2 continues to drive the outer tube to move for the assembly of the outer tube and the inner tube. Each support is lifted by the idler roller 22 when it passes by, so as to improve the smoothness of each support entering the outer tube.

[0049] A method for assembling a double-layer PE pipe, implemented using the aforementioned assembly device, includes the following steps: S1 Two-section inner tube preparation: Place the two sections of inner tube until the color marking lines on the tube body are aligned with each other. Mark the installation points of the support components on the outer wall of the inner tube. The installation points are set at equal intervals, and the installation points are reserved from the tube end for the working distance of the inner tube hot melt welding. S2 Installation of one of the inner tube support components: Align the radial groove of the support component with the color mark line at the bottom of the inner tube, and use PE glue to attach multiple support components to the marked installation points on the inner tube; The support is provided with radial grooves and axial grooves. The monitoring cable is placed in the radial groove of each support in a straight line, and the support is bound to the inner tube by passing through the axial groove of the support with PET strapping. S3 Inner Tube Welding: The inner tube with the support and monitoring cable already installed is hot-melted and welded to another inner tube using a fully automatic hot-melt welding machine; Remove the protruding adhesive strips caused by hot melt welding at the welding position, inspect the welding quality at the welding position, and install the support and monitoring cable on the other section of the inner tube using the same method as in step S2. S4 outer tube pre-installed electrofusion straight connector: Mark the insertion depth of the electrofusion straight connector at the outer tube end, and fit the electrofusion straight connector onto the end of the outer tube according to the mark; S5 Inner and Outer Tube Sleeving Installation: The inner tube and support are inserted into the outer tube using an assembly device; S6 Outer Pipe Electrofusion Welding: After the inner and outer pipes are connected and installed, the outer pipe is electrofused through the electrofusion straight tube pre-installed in S4, and the welding position is inspected.

[0050] In this invention, the double-layer pipe consists of an inner and an outer pipe that are independent of each other. The inner pipe is supported by a support member at its bottom to ensure the coaxiality of the inner and outer pipes. After a certain distance, anchors are installed between the pipes to connect long sections of pipe. The anchors are manufactured by integrally molding the inner and outer pipes. The anchors are connected to the inner pipe by hot-melt butt welding and to the outer pipe by electrofusion welding. This connection method anchors the inner and outer pipes simultaneously to form a whole, preventing circumferential and axial displacement between the support member and the outer pipe.

[0051] The protruding rubber strip removed in step S3 is folded in half and visually inspected. If the protruding rubber strip is cracked, it is cut off and re-welded. If the protruding rubber strip is not cracked, the hot melt weld joint is then inspected by a 360° surround scan using a dedicated non-destructive testing device. In step S6, the electrofusion welding position is directly inspected by a dedicated non-destructive testing device using a 360° surround scan.

[0052] When conducting 360° surround scanning inspection, non-destructive testing equipment such as phased array detectors, X-ray inspection equipment, and millimeter-wave flaw detectors can be used to perform 360° surround scanning on hot melt welds and electrofusion welds to identify welding defects such as incomplete welds, over-welding, broken heating wires, inclusions, and porosity.

[0053] First, the support components and monitoring cables are laid out on one of the inner tubes. Then, the two inner tubes are hot-melted welded using a fully automatic hot-melt welding machine. During the welding process, the monitoring cables can be retracted to avoid the welding position, which facilitates the setup of the fully automatic hot-melt welding machine. Furthermore, if the welding quality is unqualified, the welded area can be cut, reworked, and re-hot-melted, without causing the spacing between the support components at the ends of the two inner tubes to become uncontrollable.

[0054] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An assembly device for PE double-layer pipes, characterized in that, For inserting an inner tube into an outer tube in a horizontal direction, wherein the bottom of the outer wall of the inner tube is provided with a plurality of support members spaced apart along the axial direction of the inner tube, and a monitoring cable is provided below the inner tube, passing sequentially through each of the support members along the axial direction of the inner tube; the assembly device includes: Rack (1); An inner tube fixing unit is installed on the frame (1) and is used to fix the first end of the inner tube. A traction device (11) is installed on the frame (1). The traction device (11) is used to pull the outer tube sleeved on the second end of the inner tube so that the outer tube is fed to the first end of the inner tube. The lifting mechanism includes a movable support (2) and a lifting unit. The movable support (2) is assembled to be fixedly connected to one end of the outer tube near the movable support (2). The lifting unit is installed on the movable support (2) and is suspended below the inner tube. The lifting unit is configured such that, during the feeding process of the outer tube towards the first end of the inner tube, the lifting unit can lift the support member from a first height to a second height before the support member enters the outer tube, and hold the support member at the second height until at least one end of the support member enters the outer tube; when the support member is at the first height, the bottom surface of the support member is lower than the bottom surface of the inner wall of the outer tube, and when the support member is at the second height, the bottom surface of the support member is higher than the bottom surface of the inner wall of the outer tube.

2. The assembly device according to claim 1, characterized in that, The lifting unit is provided with a clearance portion for avoiding the monitoring cable. The clearance portion is configured to form a clearance channel for the monitoring cable between the two supports to pass through when the lifting unit is located between the two supports.

3. The assembly device according to claim 2, characterized in that, The lifting unit includes a roller (22), which is rotatably connected to the movable bracket (2). The axis of the roller (22) is set horizontally and is perpendicular to the axis of the inner tube and the outer tube. The radius of the roller (22) is greater than the thickness of the support member. In the axial direction of the inner tube and the outer tube, the distance between the top of the roller surface of the idler roller (22) and the end face of the outer tube near the movable bracket (2) is less than the length of the support member.

4. The assembly device according to claim 3, characterized in that, In the axial direction of the idler roller (22), the diameter of the middle part of the idler roller (22) is smaller than the diameter of both ends of the idler roller (22), and the clearance part includes an annular groove provided on the roller surface of the idler roller (22).

5. The assembly device according to claim 1, characterized in that, The traction device (11) includes a winch and a traction rope. The winch is mounted on the frame (1). One end of the traction rope is connected to the winch, and the other end of the traction rope is connected to the movable support (2).

6. The assembly device according to claim 1, characterized in that, It also includes a friction-reducing unit for supporting the outer tube below to reduce the feed resistance of the outer tube.

7. The assembly device according to claim 6, characterized in that, The friction reduction unit includes multiple support frames (4) for supporting the bottom of the outer tube and spaced apart along the axial direction of the outer tube. The outer tube is attached to the support frame (4) in a non-connected manner. The support frame (4) is provided with a limiting part (41) for preventing the outer tube from displacing relative to the support frame (4) in a second direction. The second direction is a horizontal direction perpendicular to the axial direction of the outer tube. The bottom of the support frame (4) is provided with a support wheel (42).

8. The assembly device according to claim 1, characterized in that, The bottom of the movable support (2) is provided with a roller (21), and only one roller (21) is provided in the axial direction of the outer tube.

9. The assembly device according to claim 1, characterized in that, It also includes an outer tube fixing unit; The outer tube fixing unit includes a lower support seat (3) fixedly mounted on the movable bracket (2), and an upper clamping seat (31) is detachably connected to the lower support seat (3) by bolts. The outer tube fixing unit has the same structure as the inner tube fixing unit; The lower support (3) of the inner tube fixing unit is fixedly mounted on the frame (1); Each of the upper clamping seat (31) and lower support seat (3) can be detachably equipped with an adjusting half ring (32) to adapt to different pipe diameters of the inner and outer pipes.

10. A method for assembling a double-layer PE pipe, implemented using the assembly device as described in claims 1-9, characterized in that, Includes the following steps: S1 Two-section inner tube preparation: Place the two sections of inner tube until the color marking lines on the tube body are aligned with each other. Mark the installation points of the support components on the outer wall of the inner tube. The installation points are set at equal intervals, and the installation points are reserved from the tube end for the working distance of the inner tube hot melt welding. S2 Installation of one of the inner tube support components: Align the radial groove of the support component with the color mark line at the bottom of the inner tube, and use PE glue to attach multiple support components to the marked installation points on the inner tube; The support member is provided with radial grooves and axial grooves. The monitoring cable is placed in the radial groove of each support member in a straight line, and the support member is bound to the inner tube by passing through the axial groove of the support member with PET packing strap. S3 Inner Tube Welding: The inner tube with the support and monitoring cable already installed is hot-melted and welded to another inner tube using a fully automatic hot-melt welding machine; Remove the protruding adhesive strips caused by hot melt welding at the welding position, inspect the welding quality at the welding position, and install the support and monitoring cable on the other section of the inner tube using the same method as in step S2. S4 outer tube pre-installed electrofusion straight connector: Mark the insertion depth of the electrofusion straight connector at the outer tube end, and fit the electrofusion straight connector onto the end of the outer tube according to the mark; S5 Inner and Outer Tube Sleeving Installation: The inner tube and support are inserted into the outer tube using an assembly device; S6 Outer Pipe Electrofusion Welding: After the inner and outer pipes are connected and installed, the outer pipe is electrofused through the electrofusion straight tube pre-installed in S4, and the welding position is inspected. The protruding rubber strip removed in step S3 is folded and visually inspected. If the protruding rubber strip is cracked, it is cut off and re-welded. If the protruding rubber strip is not cracked, the hot melt weld joint is then inspected by a 360° surround scan using a dedicated non-destructive testing device. In step S6, the electrofusion welding position is directly inspected by a dedicated non-destructive testing device using a 360° circumferential scanning method.

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