Production process of polyethylene pipe for industrial building heating ventilation

Abstract

This invention discloses a manufacturing process for polyethylene pipes used in industrial building heating and ventilation. The key technical points are: the polyethylene pipe is a double-layered pipe, comprising an inner pipe and an outer pipe nested together, with a filling layer between the inner and outer pipes; the filling layer is foamed and filled using a filling device; the filling device includes two sets of annular baffle assemblies, which are fitted into the annular cavity between the inner and outer pipes, forming a filling cavity between the two sets of annular baffle assemblies; during filling, the two sets of baffle assemblies move closer together, material fills the filling cavity, and the increased material pushes the baffle assemblies to move in opposite directions, extending the axial length of the filling cavity to form the filling layer. This invention can maintain the uniformity of the filling layer inside the pipe and avoid the formation of filling voids within the filling layer, thus improving the internal stability of the pipe.

Description

Technical Field

[0001] This invention relates to an insulated pipe, and more specifically, to a manufacturing process for a polyethylene pipe for heating and ventilation in industrial buildings, and also to a filling device for the filling layer inside the pipe. Background Technology

[0002] Heating pipes need to transport the heat medium for heating, so the insulation requirements for the pipe body are relatively high. Often, the pipe body needs to be set up with a double-layer structure, and an insulating layer is filled in between the two layers to form a good insulation barrier between the pipe walls, thereby maintaining the heating efficiency.

[0003] Most of the filling layers are made of foamed material. By filling the space between two pipe layers with foamed material, a foamed insulation layer can be formed. For pipes with larger diameters, the production process requires first processing the inner and outer pipe layers separately, then fitting the inner pipe inside the outer pipe, and filling the space between the two pipe layers with foamed material. The foamed material supports and maintains the inner pipe in the center position of the outer pipe, thus completing the pipe processing.

[0004] However, during the filling process, the inner tube may become misaligned, resulting in the inner tube being offset from the outer tube. This causes the filling layer on one side to be thinner, affecting the insulation performance of the pipe. Furthermore, the misalignment also affects the overall structural strength and stability of the pipe. If the end is also misaligned, it will affect the pipe's connection and sealing. Moreover, due to the long axial length of the pipe, the foaming material cannot be evenly distributed throughout the pipe during filling, potentially creating gaps in a section or location. This also affects the insulation performance, and the lack of internal support from the filling layer in these areas will negatively impact the external strength of the pipe.

[0005] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems by providing a production process for polyethylene pipes used in industrial building heating and ventilation, which has good filling uniformity and can improve the thermal insulation performance and overall stability of the pipe.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a production process for polyethylene pipes for heating and ventilation in industrial buildings, wherein the polyethylene pipe is a double-layer pipe, including an inner pipe and an outer pipe nested together, and a filling layer is provided between the inner pipe and the outer pipe; the filling layer is foamed and filled by a filling device; the filling device includes two sets of annular baffle assemblies, the baffle assemblies being fitted into the annular cavity between the inner pipe and the outer pipe, and a filling cavity is formed between the two sets of annular baffle assemblies; during filling, the two sets of baffle assemblies move closer to each other, the material fills into the filling cavity, the increased material pushes the baffle assemblies to move in opposite directions, and the axial length of the filling cavity extends to form the filling layer.

[0008] The present invention is further configured such that the stop assembly includes an inner stop ring and an outer stop ring, the inner ring of the inner stop ring is fitted with the inner tube and the outer diameter is smaller than the inner diameter of the outer tube; a ring sleeve is fixedly connected to one side of the two inner stop rings facing away from each other, the ring sleeve is coaxially arranged with the inner stop ring and fitted with the inner tube; the inner hole of the outer stop ring is fitted with the ring sleeve and the outer stop ring is sleeved on the outer circumference of the ring sleeve, which can realize axial sliding adjustment.

[0009] The present invention is further configured such that an outwardly protruding retaining ring is provided at the end of the ring sleeve away from the inner retaining ring, and a supporting spring is elastically pressed between the inner retaining ring and the outer retaining ring, and the retaining ring is used for blocking and limiting.

[0010] The present invention is further configured such that the baffle assembly further includes a filling tube, the filling tube passing through the inner side of the outer baffle ring and extending into the tube hole of the inner baffle ring, and a nozzle is provided at the end of the filling tube, the nozzle passing through the tube hole and extending to the side of the inner baffle ring facing the filling cavity.

[0011] The invention is further configured such that the outer periphery of the outer retaining ring is connected to an elastic edge, the elastic edge being used to elastically engage with the inner periphery of the outer tube.

[0012] The present invention is further configured such that the stop assembly includes a plurality of guide wheels, each guide wheel being arranged in a ring array between the inner stop ring and the outer stop ring. The guide wheels are rotatably supported by a support block, the support block being slidably connected to the outer stop ring and capable of radial sliding adjustment. The guide wheels are used to extend outward relative to the inner circumference of the outer tube to achieve axial positioning.

[0013] The invention is further configured such that a slider is fixedly connected to the side of the support block facing the outer retaining ring, a groove is formed in the radial direction of the outer retaining ring, the slider is embedded in the groove to form a radial sliding connection structure, and a limiting spring is provided in the groove. The limiting spring elastically presses against the groove end face of the slider and the groove, and is used to elastically push the slider to move towards the inner tube. Grooves for installing the limiting spring are formed on both the groove end face of the groove and the slider.

[0014] The present invention is further configured such that the slider passes through the slide groove and is fixedly connected to the limiting block, and the outer retaining ring is provided with a limiting groove on the outward side that is adapted to slide with the limiting block.

[0015] The invention is further configured such that a convex ring is fixedly connected to the side of the inner retaining ring facing the outer retaining ring, the convex ring being used to press against the support block, the outer periphery of the convex ring gradually shrinking towards the outer retaining ring and forming a first inclined surface; a second inclined surface is formed on the side of the support block facing the inner retaining ring, the first inclined surface and the second inclined surface cooperate with each other to realize the pressing transmission; when the inner retaining ring and the outer retaining ring approach each other, the convex ring pushes the support block and the guide wheel to move outward, and realizes the annular expansion movement of the guide wheel, and axial positioning is achieved through the guide wheel and the inner periphery of the outer tube.

[0016] The present invention also provides a tube filling device, wherein the tube is a double-layer pipe, including an inner tube and an outer tube that are nested together, and a filling layer is provided between the inner tube and the outer tube; the filling layer is foamed; the filling device is used to fill the filling layer and includes two sets of annular baffle assemblies, the baffle assemblies being fitted into the annular cavity between the inner tube and the outer tube, and a filling cavity is formed between the two sets of annular baffle assemblies.

[0017] In summary, the present invention has the following beneficial effects:

[0018] During the filling process of the middle layer of the pipe body, the filling device is used to fill the foam material. During the filling process, the foam material can be squeezed and limited to ensure that the inner and outer pipes can be filled. This improves the density of the filling layer, eliminates the filling gaps between the two layers, and ensures that all parts of the pipe have good thermal insulation and strength performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a polyethylene pipe for heating and ventilation in industrial buildings according to the present invention;

[0020] Figure 2 This is a schematic diagram of the filling device of the present invention;

[0021] Figure 3 This is a partially enlarged structural diagram of the baffle assembly of the present invention. Figure 1 ;

[0022] Figure 4 This is a partially enlarged structural diagram of the baffle assembly of the present invention. Figure 2 ;

[0023] Figure 5 This is a schematic diagram of the outer retaining ring and elastic edge of the present invention.

[0024] Reference numerals: 1. Tube body; 101. Outer tube; 102. Inner tube; 103. Filling layer; 2. Baffle assembly; 201. Filling cavity; 3. Outer retaining ring; 31. Inner hole; 32. Slide groove; 33. Limiting spring; 34. Groove; 35. Limiting slot; 36. Elastic edge; 4. Inner retaining ring; 41. Ring sleeve; 42. Stop block; 43. Tube hole; 5. Guide wheel; 6. Support spring; 7. Filling tube; 71. Nozzle; 8. Support block; 81. Slider; 82. Limiting block; 83. Protruding ring; 84. Inclined surface one; 85. Inclined surface two. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This embodiment discloses a manufacturing process for polyethylene pipes used in industrial building heating and ventilation systems, such as... Figure 1 As shown, the polyethylene pipe is a double-layer pipe, including an inner pipe 102 and an outer pipe 101 nested together. Both the inner pipe 102 and the outer pipe 101 are made of polyethylene material. There is a filling layer 103 between the inner pipe 102 and the outer pipe 101. The filling layer 103 is a foamed material. Through the foamed filling layer 103, a foamed heat-insulating filling structure can be formed in the middle, which can achieve a good heat-insulating effect.

[0027] Because the filling layer 103 between the inner pipe 102 and the outer pipe 101 has a large thickness and is filled by a filling device, the foaming material can be squeezed and limited during the filling process to ensure that the space between the inner pipe 102 and the outer pipe 101 can be filled, thereby increasing the density of the filling layer 103, eliminating the filling gap between the two layers, and thus ensuring that the pipe has good thermal insulation and strength performance at all locations.

[0028] This embodiment discloses a filling device for a tube body 1, such as Figure 2As shown, the filling device includes two sets of annular baffle assemblies 2. During filling, the baffle assemblies 2 are fitted into the annular cavity between the inner pipe 102 and the outer pipe 101, with the pipe inserted into the middle position of the outer pipe 101 at its end. A filling cavity 201 is formed between the two sets of annular baffle assemblies 2. The two sets of baffle assemblies 2 are close to each other, and material is injected into the filling cavity 201 from the filling pipe 7 in the baffle assembly 2, forming material filling between the inner pipe 102 and the outer pipe 101. As material is continuously filled, the increasing material pushes the baffle assemblies 2 to move in opposite directions, and the axial length of the filling cavity 201 extends to form a filling layer 103. This filling device can use the material filling action between two layers of pipes, and the resulting filling layer 103 will be relatively dense, basically eliminating the gaps and incomplete filling that may occur during the filling process.

[0029] like Figure 3 , 4 As shown, the baffle assembly 2 includes an inner baffle ring 4 and an outer baffle ring 3. The inner ring of the inner baffle ring 4 is fitted with the inner tube 102 to block the filling material. The outer diameter of the inner baffle ring is slightly smaller than the inner diameter of the outer tube 101, allowing the inner baffle ring 4 to move smoothly within the outer tube 101. A ring sleeve 41 is fixedly connected to one side of the two inner baffle rings 4 facing away from each other. The ring sleeve 41 is coaxially arranged with the inner baffle ring 4 and has the same inner diameter as the inner baffle ring 4. It is also fitted with the inner tube 102, and its inner diameter is slightly larger than the outer diameter of the inner tube 102, so that the inner baffle ring 4 will not cause significant obstruction or interference between the inner tubes 102 during movement, allowing the inner baffle ring 4 to move smoothly.

[0030] An elastic edge 36 is connected to the outer periphery of the outer retaining ring 3. The elastic edge 36 is made of rubber and can be elastically engaged with the inner periphery of the outer tube 101. Stability is achieved through the friction between the elastic edge 36 and the outer tube 101. After being subjected to a certain axial thrust, the outer retaining ring 3 can move axially without affecting the overall axial movement adjustment of the retaining body assembly 2.

[0031] The inner hole 31 of the outer retaining ring 3 is adapted to the ring sleeve 41, and the outer retaining ring 3 is sleeved on the outer circumference of the ring sleeve 41, enabling axial sliding adjustment. A protruding stop block 42 is formed at the end of the ring sleeve 41 away from the inner retaining ring 4. The stop block 42 can block and limit the position of the outer retaining ring 3, creating a sliding stroke between the stop block 42 and the inner retaining ring 4. To maintain the sliding stability of the outer retaining ring 3, guide ribs can be machined on the inner circumference of the outer retaining ring 3 and the outer circumference of the ring sleeve 41, forming a stable axial adjustment structure between the outer retaining ring 3 and the inner retaining ring 4.

[0032] A support spring 6 is elastically pressed between the inner retaining ring 4 and the outer retaining ring 3. The support spring 6 is fitted around the outer circumference of the ring sleeve 41, and its two ends elastically press against the inner retaining ring 4 and the outer retaining ring 3 respectively. Through the elasticity of the support spring 6, the outer retaining ring 3 can be pressed against the stop block 42, and the positions of the inner retaining ring 4 and the outer retaining ring 3 can be kept in a relatively stable state.

[0033] The baffle assembly 2 also includes a filling tube 7, which is a flexible tube connected to an external material injection device to inject the material to be filled into the filling cavity 201. Specifically, the filling tube 7 extends from the side of the baffle ring away from the filling cavity 201, passes through the outer baffle ring 3, and extends into the tube hole 43 of the inner baffle ring 4. The tube hole 43 passes through the inner baffle ring 4, and a nozzle 71 is connected to the filling tube 7 extending into the tube hole 43. The nozzle 71 can extend from the tube hole 43 to the side facing the filling cavity 201, thereby filling the cavity.

[0034] The baffle assembly 2 also includes several guide wheels 5, which are arranged in a circular array between the inner baffle ring 4 and the outer baffle ring 3. The guide wheels 5 can extend outward and make abutting contact with the inner circumferential wall of the inner tube 102. Since the outer diameters of the inner baffle ring 4 and the outer baffle ring 3 of the baffle assembly 2 are smaller than the inner diameter of the outer tube 101, the elastic edge 36 on the outer circumference of the outer baffle ring 3 mainly plays a role in maintaining stability. With the guidance of the guide wheels 5, axial centering can be achieved. During the filling process, the inner baffle ring 4 is squeezed and moves axially towards the outer baffle ring 3, resulting in relative sliding. At the same time, it can drive each guide wheel 5 to extend outward at the same distance. Each guide wheel 5 can form an axial position on the outer circumference, supporting the baffle assembly 2 in the outer tube 101 and forming a stable support. Since the guide wheels 5 are in a uniform circular array, the baffle assembly 2 can be supported to maintain a good concentricity with the outer tube 101. And with the rolling guidance of the guide wheels 5, the baffle assembly 2 can maintain smooth axial movement. The baffle assembly 2 is limited by the shaft hole in the inner baffle ring 4 and the ring sleeve 41, which can support the inner tube 102 in the middle position of the outer tube 101. This can keep the inner tube 102 and the outer tube 101 in a stable and uniform state during the filling process, keep the interior of the filling layer 103 tight and free of any gaps, and ensure that the axially uniform tube 1 has good structural stability and uniform heat preservation effect.

[0035] Specifically, the guide wheel 5 is rotatably supported by the support block 8. The support block 8 corresponds one-to-one with the guide wheel 5 and is installed between the inner retaining ring 4 and the outer retaining ring 3. The support block 8 and the outer retaining ring 3 are slidably connected, which can realize radial sliding adjustment, thereby guiding the movement of the guide wheel 5 during the adjustment process.

[0036] A slider 81 is fixedly connected to the side of the support block 8 facing the outer retaining ring 3. A radial groove 32 is formed at the corresponding position of the outer retaining ring 3. The slider 81 is embedded in the groove 32 to form a radial sliding connection structure. A limiting spring 33 is installed in the groove 32. Through the elastic action of the limiting spring 33, the slider 81, the support block 8, and the guide wheel 5 can be moved inward, thereby retracting the guide wheel 5 into the inner position of the inner retaining ring 4 and the outer retaining ring 3, thus acting as a force-bearing guide wheel 5.

[0037] like Figure 4 As shown, the limiting spring 33 elastically presses against the end face of the slider 81 and the groove 32, and can elastically push the slider 81 to move towards the inner tube 102. In order to maintain the installation stability of the limiting spring 33, grooves 34 can be opened on the corresponding end face of the groove 32 and the slider 81, and the end of the limiting spring 33 can be embedded into the groove 34, thereby maintaining the stability of the limiting spring 33.

[0038] To further maintain the stability of the guide wheel 5 during sliding adjustment, a limiting block 82 can be fixedly connected at the position where the slider 81 extends through the slide groove 32 to the other side of the outer retaining ring 3. The size of the limiting block 82 is larger than the width of the slide groove 32, which serves as a limiting function to keep the slider 81 stably within the slide groove 32. In addition, a limiting groove 35 can be opened on the outward side of the outer retaining ring 3 to accommodate the limiting block 82, which further guides the sliding and maintains the stability of the guide wheel 5 during sliding.

[0039] like Figure 3 , 4 As shown, in order to achieve the linkage between the guide wheel 5 and the inner retaining ring 4 and the outer retaining ring 3, a pressure linkage structure can be set between the inner retaining ring 4 and the support block 8 of the guide wheel 5. When the inner retaining ring 4 moves towards the outer retaining ring 3, it can push the support block 8 and the guide wheel 5 to move outward in the peripheral direction through pressure, so that the guide wheel 5 can extend outward from the outer periphery of the retaining body assembly 2 and form a pressure limit with the inner wall of the outer tube 101, keeping the inner tube 102 in the axial middle position, playing a positioning and guiding role, and improving the uniformity and stability of the position filling layer 103.

[0040] Specifically, a fixed convex ring 83 is formed on the side of the inner retaining ring 4 facing the outer retaining ring 3. The convex ring 83 can be integrated with the outer retaining ring 3, and a pressing fit is achieved between the convex ring 83 and the support block 8. The outer periphery of the convex ring 83 gradually tapers towards the outer retaining ring 3, forming a tapered inclined surface 84. A second inclined surface 85 is machined on the side of the support block 8 facing the inner retaining ring 4. The two inclined surfaces 84 fit together, are parallel, and press against each other, enabling pressing transmission. During the process of the convex ring 83 pressing against the support block 8, the axial movement can be converted into radial movement of the support block 8 through the action of the first inclined surface 84 and the second inclined surface 85, thereby driving the guide wheel 5 to achieve outward extension and retraction adjustment.

[0041] like Figure 5 As shown, there are two elastic edges 36, located on the lower sides of the outer retaining ring 3, forming two support points on the left and right. After the retaining assembly 2 is installed, it is supported by the two elastic edges 36 on the lower side of the outer retaining ring 3, and is positioned by friction between the retaining assembly 2 and the interior of the outer tube 101. Since the outer diameter of the outer retaining ring 3 is smaller than that of the outer tube 101, the retaining assembly 2 is positioned lower, and the elastic edges 36 provide frictional blocking. During the filling process, each guide wheel 5 extends outward, forming a ring-shaped support structure on the outer periphery. This supports the retaining assembly 2 at the center of the tube 1. After the retaining assembly 2 is lifted, the pressure between the elastic edges 36 and the inner wall of the outer tube 101 decreases, and the friction decreases, making it easier for the retaining assembly 2 to move axially outward, thereby achieving the filling of the filling layer 103.

[0042] During the filling process, the outer periphery of the outer retaining ring 3 and the outer tube 101 generate extrusion friction, which can maintain the retaining assembly 2 in a relatively stable state between the inner tube 102 and the outer tube 101. The required material can be filled into the filling cavity 201 between the two sets of retaining assemblies 2 through the filling tube 7. Generally, foamed material can be used to form a foamed filling layer 103. As the material is gradually filled, the filling cavity 201 is filled. Due to the obstruction and limitation of the retaining assembly 2 during the filling process, the filled material can be restricted to a small space, so that the filled material can completely fill the filling cavity 201. As the material is further injected, it will squeeze the baffle assembly 2, pushing the innermost inner ring 4 of the baffle assembly 2 axially outward. At this time, due to the certain frictional resistance between the outer ring and the outer tube 101, a support point is formed. A certain amount of compression will be generated between the inner ring and the outer ring, which will drive the guide wheel 5 to extend outward and form a uniform ring-shaped pressure support on the inner circumferential surface of the outer tube 101. Axial positioning is achieved through the guide wheel 5 and the inner circumference of the outer tube 101, and the baffle assembly 2 can be moved stably and smoothly, maintaining the uniform filling effect of the filling layer 103.

[0043] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for polyethylene pipes used in industrial building heating and ventilation, characterized in that, The polyethylene pipe is a double-layer pipe, including an inner pipe (102) and an outer pipe (101) that are nested together. A filling layer (103) is provided between the inner pipe (102) and the outer pipe (101). The filling layer (103) is foamed and is filled by a filling device. The filling device includes two sets of annular baffle assemblies (2). The baffle assemblies (2) are used to fit into the annular cavity between the inner pipe (102) and the outer pipe (101). A filling cavity (201) is formed between the two sets of annular baffle assemblies (2). During filling, the two sets of baffle assemblies (2) move closer to each other. The material is filled into the filling cavity (201). The increased material pushes the baffle assemblies (2) to move in opposite directions. The axial length of the filling cavity (201) is extended to form the filling layer (103). The baffle assembly (2) includes an inner baffle ring (4) and an outer baffle ring (3). The inner ring (4) is fitted with the inner tube (102) and its outer diameter is smaller than the inner diameter of the outer tube (101). A ring sleeve (41) is fixedly connected to one side of each of the two inner baffle rings (4). The ring sleeve (41) is coaxially arranged with the inner baffle ring (4) and fitted with the inner tube (102). The inner hole (31) of the outer baffle ring (3) is fitted with the ring sleeve (41). The outer baffle ring (3) is sleeved on the outer circumference of the ring sleeve (41) and can be axially slidably adjusted. The end of the ring sleeve (41) away from the inner retaining ring (4) is provided with an outwardly protruding retaining ring. The inner retaining ring (4) and the outer retaining ring (3) are elastically pressed together by a support spring (6), and the retaining ring is used to block and limit the movement. The baffle assembly (2) also includes a filling tube (7), which passes through the inner side of the outer baffle ring (3) and extends into the tube hole (43) of the inner baffle ring (4). A nozzle (71) is provided at the end of the filling tube (7), which passes through the tube hole (43) and extends to the side of the inner baffle ring (4) facing the filling cavity (201). The baffle assembly (2) also includes several guide wheels (5), which are arranged in a ring array between the inner baffle ring (4) and the outer baffle ring (3). The guide wheels (5) are rotatably supported by a support block (8), which is slidably connected to the outer baffle ring (3) and can be adjusted in the radial direction. The guide wheels (5) are used to extend outward relative to the inner circumference of the outer tube (101) to achieve axial positioning. The support block (8) is fixedly connected to a slider (81) on the side facing the outer retaining ring (3). The outer retaining ring (3) has a groove (32) in the radial direction. The slider (81) is embedded in the groove (32) to form a radial sliding connection structure. A limiting spring (33) is provided in the groove (32). The limiting spring (33) elastically presses against the groove end face of the slider (81) and the groove (32) to elastically push the slider (81) to move towards the inner tube (102). The inner retaining ring (4) is fixedly connected to a protruding ring (83) on the side facing the outer retaining ring (3). The protruding ring (83) is used to press against the support block (8). The outer periphery of the protruding ring (83) gradually shrinks towards the outer retaining ring (3) and forms a first inclined surface (84). The support block (8) forms a second inclined surface (85) on the side facing the inner retaining ring (4). The first inclined surface (84) and the second inclined surface (85) cooperate with each other to realize the pressing transmission. When the inner retaining ring (4) and the outer retaining ring (3) approach each other, the protruding ring (83) pushes the support block (8) and the guide wheel (5) to move outward, and realizes the annular expansion movement of the guide wheel (5). The guide wheel (5) and the inner periphery of the outer tube (101) are axially positioned.

2. The industrial building heating and ventilation polyethylene pipe production process according to claim 1, characterized in that, The outer retaining ring (3) has an elastic edge (36) connected to its outer periphery, which is used to elastically engage with the inner periphery of the outer tube (101).

3. The industrial building heating and ventilation polyethylene pipe production process according to claim 1, characterized in that, The slider (81) passes through the slide groove (32) and is fixedly connected to the limiting block (82). The outer retaining ring (3) is provided with a limiting groove (35) on the outward side that is adapted to slide with the limiting block (82).

4. A filling device for polyethylene pipes for industrial building heating, ventilation and air conditioning, characterized in that, The polyethylene pipe is a double-layer pipe, including an inner pipe (102) and an outer pipe (101) that are nested together, with a filling layer (103) provided between the inner pipe (102) and the outer pipe (101); the filling layer (103) is foamed; the filling device is used to fill the filling layer (103), including two sets of annular baffle assemblies (2), the baffle assemblies (2) are used to fit into the annular cavity between the inner pipe (102) and the outer pipe (101), and a filling cavity (201) is formed between the two sets of annular baffle assemblies (2); it is produced using the polyethylene pipe production process for heating and ventilation of industrial buildings as described in any one of claims 1-3.

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