Operation method of a spraying system for polyurethane insulation layer of thermal insulation pipe

Abstract

This invention belongs to the field of thermal insulation pipe processing technology, specifically relating to a spraying system for a polyurethane insulation layer on thermal insulation pipes. The system includes a frame and spray guns mounted on the frame for spraying polyurethane. Multiple sets of spray guns are arranged around the periphery of the thermal insulation pipe. A movable base is also provided on the frame, and a wire winding mechanism is mounted on the movable base. The spray guns and the wire winding mechanism each have the freedom to reciprocate along the axial direction of the thermal insulation pipe via the movable base. The fiber mesh is wound onto the adhesive layer formed by the polyurethane spraying using the wire winding mechanism. This invention, by laying a fiber mesh as a reinforcing layer between adjacent adhesive layers, allows the polyurethane to overflow outwards along the mesh openings of the fiber mesh during the foaming of the previous layer, forming a rough surface. This increases the contact area with the next layer of polyurethane, significantly improving the interlayer bonding strength and enhancing the overall structural stability of the insulation layer.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation pipe processing technology, specifically relating to a spraying system for polyurethane insulation layer of thermal insulation pipe and its operation method. Background Technology

[0002] Insulated pipes are used in centralized heating, long-distance oil and gas pipelines, municipal water supply and drainage and other fields. For insulated pipes with large diameter and long distance, due to the large temperature difference between the transported medium and the external environment, as well as the large volume and wide heat dissipation area of ​​the pipe itself, a thicker insulation layer is required to meet its insulation requirements.

[0003] Due to the limitations of polyurethane foaming properties, a single spray application cannot directly form an insulation layer that meets the design thickness requirements. If a single spray application is too thick, the heat generated during polyurethane foaming cannot be dissipated quickly, leading to defects such as uneven foaming, incomplete curing, and internal cracks. Therefore, the industry commonly employs a multi-layer, layered spraying process to prepare thick insulation layers. This involves first spraying a layer of polyurethane and allowing it to fully cure, then spraying the next layer of polyurethane onto the cured polyurethane layer. By repeating this process multiple times, the insulation layer achieves the designed thickness.

[0004] However, after the top layer of polyurethane cures, its surface becomes dense and smooth. When the next layer of polyurethane is sprayed, it can only connect with the substrate through weak physical adsorption and limited chemical bonding, resulting in weak adhesion between adjacent layers. During long-term use, this layered insulation layer is highly susceptible to delamination and peeling between adjacent layers due to factors such as thermal expansion and contraction caused by environmental temperature changes, vibrations from pipeline operation, and soil stress, ultimately leading to insulation layer detachment. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a spraying system and operation method for a polyurethane insulation layer of a thermal insulation pipe. By laying a fiber mesh as a reinforcing layer between adjacent adhesive layers, when the upper layer of polyurethane foams, the polyurethane overflows outward along the mesh openings of the fiber mesh and forms a rough surface, increasing the contact area with the lower layer of polyurethane, greatly improving the interlayer bonding force, and significantly enhancing the overall structural stability of the insulation layer.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] A spraying system for a polyurethane insulation layer on a thermal insulation pipe includes a frame and spray guns mounted on the frame for spraying polyurethane. Multiple sets of spray guns are arranged around the periphery of the thermal insulation pipe. A movable base is also provided on the frame, and a wire wrapping mechanism is provided on the movable base. The spray guns and the wire wrapping mechanism each have the freedom to reciprocate along the axial direction of the thermal insulation pipe via the movable base. The fiber web is wound onto the adhesive layer formed by the polyurethane spraying by means of the wire wrapping mechanism.

[0008] The frame is equipped with guide rails, and the movable seat slides with the guide rails and has the freedom to translate horizontally. The movable seat is also equipped with a ring-shaped fixing collar, which is sleeved on the outside of the insulation pipe. The fixed end of the spray gun is connected to the fixing collar. The two sides of the frame are also symmetrically equipped with rotating rollers that rotate with the frame. One rotating roller is connected to a drive motor, and the other rotating roller is mounted on a clamping seat that slides with the guide rails. The insulation pipe rotates with the help of the rotating rollers and forms a relative spiral motion with the spray gun.

[0009] The fixed end of the spray gun is hinged to the inner wall of the fixed collar by means of a swing assembly. The spraying end of the spray gun has a swing freedom by means of the swing assembly. The distance between the spraying end of the spray gun and the heat insulation pipe is adjustable by means of its swing freedom.

[0010] The oscillating assembly includes a fixed block, a transmission gear set, and a rotating gear ring. The fixed block is fixedly connected to a fixed collar. The fixed end of the spray gun is fixedly connected to a hinge shaft and hinged to a groove on the surface of the fixed block via the hinge shaft. The rotating gear ring is coaxially arranged with the fixed collar and has a degree of freedom of rotation. The inner wall of the rotating gear ring is provided with teeth. The end of the hinge shaft is connected to the rotating gear ring via the transmission gear set. The hinge shaft rotates synchronously with the rotation of the rotating gear ring and drives the spray gun to oscillate.

[0011] The transmission gear set includes a driven gear, a reversing bevel gear, and a transmission shaft that is sleeved with the driven gear. The driven gear meshes with the teeth of a rotating gear ring. The reversing bevel gear is provided with two sets that mesh with each other. One set of reversing bevel gears is connected to the transmission shaft, and the other set of reversing bevel gears is connected to a hinge shaft. The driven gear drives the hinge shaft to rotate by means of the reversing bevel gear.

[0012] The winding mechanism includes a support collar and a rotating collar rotatably connected to the inner side of the support collar. Both the support collar and the rotating collar are coaxially arranged with the fixed collar. The support collar and the fixed collar are coaxially arranged on a movable seat. A winding wheel for storing the fiber web is provided on the side of the rotating collar. The fiber web on the winding wheel is spirally wound along the axial direction of the insulation pipe by means of the rotation of the rotating collar and the translation of the movable seat.

[0013] Both sides of the fixing collar are equipped with a net-winding mechanism.

[0014] The fiber web is a nylon fiber web with a pore size of 1-3 cm.

[0015] An operating method for a polyurethane insulation layer spraying system for thermal insulation pipes includes the following steps:

[0016] S1. Connect the two ends of the insulation pipe to the rotating rollers on both sides of the frame respectively, and adjust the spray gun angle so that the spraying end of the spray gun faces the insulation pipe.

[0017] S201. Activate the movable seat and the winding mechanism, and move it from one end of the insulation pipe to the other end;

[0018] S202, Multiple sets of spray guns move together with the moving base and spray polyurethane onto the insulation pipe to form an upper adhesive layer;

[0019] S203, the fiber web is spirally wound onto the surface of the upper adhesive layer along with the winding mechanism and the moving seat to form the upper reinforcement layer;

[0020] S204. Wait for the upper adhesive layer to foam and overflow along the mesh of the upper reinforcement layer. After the upper adhesive layer solidifies, it forms an upper thermal insulation layer together with the upper reinforcement layer.

[0021] S301, the moving seat moves in the opposite direction, and the spray gun sprays polyurethane onto the upper insulation layer surface to form the lower adhesive layer;

[0022] S302, the fiber web is spirally wound onto the surface of the lower adhesive layer along with the winding mechanism and the moving seat to form the lower reinforcement layer;

[0023] S303. Wait for the lower adhesive layer to foam and overflow along the mesh of the lower reinforcement layer. After the lower adhesive layer solidifies, it forms a lower insulation layer together with the lower reinforcement layer.

[0024] S4. Repeat steps S2-S3 to form the insulation layer of the insulation pipe through multiple layers of insulation.

[0025] The beneficial effects of this invention are:

[0026] In this invention, a fiber mesh is laid between adjacent adhesive layers as a reinforcing layer. When the first layer of polyurethane is sprayed, the fiber mesh is simultaneously wound onto the insulation pipe. Before the polyurethane foams and solidifies, the fiber mesh has already wrapped the polyurethane. When the polyurethane foams, the polyurethane will overflow outward along the mesh openings of the fiber mesh, thus making the surface of the insulation layer rough. This rough surface can increase the contact area with the next layer of polyurethane, so that the next layer of polyurethane can form a physical interlock with the rough surface after spraying, greatly improving the interlayer bonding force and significantly enhancing the overall structural stability of the insulation layer. Attached Figure Description

[0027] Figure 1 This is a side view of the spraying system.

[0028] Figure 2 This is a top view of the spraying system.

[0029] Figure 3 This is a schematic diagram of the spray gun structure;

[0030] Figure 4 This is a schematic diagram of the swing assembly.

[0031] Figure 5 This is a schematic diagram of the wire wrapping mechanism;

[0032] Figure 6 This is a schematic diagram of a single-layer insulation layer;

[0033] Figure 7 This is a schematic diagram of the double-layer insulation layer.

[0034] In the attached diagram, 1 is the frame, 2 is the spray gun, 3 is the movable seat, 4 is the insulation pipe, 5 is the wire wrapping mechanism, 501 is the support collar, 502 is the rotating collar, 503 is the reel, 6 is the insulation layer, 601 is the adhesive layer, 602 is the reinforcing layer, 7 is the guide rail, 8 is the fixed collar, 9 is the rotating roller, 10 is the swing assembly, 1001 is the fixed block, 1002 is the rotating gear ring, 1003 is the hinge shaft, 1004 is the driven gear, 1005 is the reversing bevel gear, 1006 is the transmission shaft, 11 is the drive motor, and 12 is the clamping seat. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0036] Specific embodiments, such as Figure 1-7 As shown, the present invention provides a spraying system for a polyurethane insulation layer 6 of a thermal insulation pipe 4, including a frame 1 and a spray gun 2 for spraying polyurethane, which is mounted on the frame 1. Multiple sets of spray guns 2 are arranged around the periphery of the thermal insulation pipe 4. A movable seat 3 is also provided on the frame 1. A wire wrapping mechanism 5 is provided on the movable seat 3. The spray gun 2 and the wire wrapping mechanism 5 have the freedom to reciprocate along the axial direction of the thermal insulation pipe 4 by means of the movable seat 3. The fiber web is wound onto the adhesive layer 601 formed by the polyurethane spraying by means of the wire wrapping mechanism 5.

[0037] Due to the limitations of polyurethane foaming properties, a single spray application cannot directly form an insulation layer 6 that meets the design thickness requirements. Therefore, the industry commonly employs a multi-layer, layered spraying process to prepare thick insulation layers 6. However, after the upper layer of polyurethane cures, its surface becomes dense and smooth. When the next layer of polyurethane is sprayed, it can only connect to the substrate through weak physical adsorption and limited chemical bonding, resulting in weak adhesion between adjacent layers. During long-term use, this layered insulation layer 6 is highly susceptible to delamination and peeling between adjacent layers due to factors such as thermal expansion and contraction caused by environmental temperature changes, vibrations during pipeline operation, and soil stress, ultimately leading to the detachment of the insulation layer 6.

[0038] Therefore, in this invention, a fiber mesh is laid between adjacent adhesive layers 601 as a reinforcing layer 602. When the first layer of polyurethane is sprayed, the fiber mesh is simultaneously wound onto the insulation pipe 4. Before the polyurethane foams and solidifies, the fiber mesh already encapsulates the polyurethane. When the polyurethane foams, the polyurethane will overflow outwards along the mesh openings of the fiber mesh. Figure 6 As shown, this results in a roughened surface for the insulation layer. This roughened surface increases the contact area with the next layer of polyurethane, allowing the next layer of polyurethane to physically bond with the roughened surface after spraying. Figure 7 As shown, the interlayer bonding strength is greatly improved, significantly enhancing the overall structural stability of the insulation layer 6.

[0039] In this system, the spray gun 2 and the wire wrapping mechanism 5 are integrated on the moving base 3, so that both have the freedom to move back and forth along the axial direction of the insulation pipe 4, thereby realizing the synchronous operation of spraying and wire wrapping. This ensures that the fiber mesh can be quickly wrapped around the surface of the adhesive layer 601 that has not yet been fully foamed, and with the help of the flexibility of the continuously expanding adhesive layer 601, it is embedded in the adhesive layer 601, cutting the surface of the adhesive layer 601 into a grid shape, which facilitates the continued bonding of the subsequent adhesive layer 601.

[0040] like Figure 1-2 As shown, the frame 1 is provided with a guide rail 7, the movable seat 3 is slidably engaged with the guide rail 7 and has the freedom to translate in the horizontal direction, the movable seat 3 is also provided with a ring-shaped fixing collar 8, the fixing collar 8 is sleeved on the outside of the insulation pipe 4, the fixed end of the spray gun 2 is connected to the fixing collar 8, the two sides of the frame 1 are also symmetrically provided with rotating rollers 9 that rotate with the frame 1, one side of the rotating roller 9 is connected to a drive motor 11, and the other side of the rotating roller 9 is provided on a clamping seat 12 that is slidably connected to the guide rail 7, the insulation pipe 4 rotates with the help of the rotating roller 9 and forms a relative spiral motion with the spray gun 2.

[0041] The rotating rollers 9 on both sides of the frame 1 drive the insulation pipe 4 to rotate, and the moving seat 3 drives the spray gun 2 to move horizontally along the guide rail 7. The combination of the two causes the spray gun 2 and the insulation pipe 4 to form a relative spiral motion, which is equivalent to the spray gun 2 performing a spiral full-coverage spraying on the insulation pipe 4. With the help of multiple sets of spray guns 2 arranged in a circle, the spray gun 2 can cover the surface of the insulation pipe 4 with a layer of polyurethane during the single-pass movement of the moving seat 3, which greatly improves the spraying efficiency of the insulation layer 6 and further improves the uniformity of the spraying of the insulation layer 6. The clamping seat 12 is displaced when clamping and unclamping the insulation pipe 4.

[0042] like Figure 3-4 As shown, the fixed end of the spray gun 2 is hinged to the inner wall of the fixed collar 8 by means of the swing assembly 10, and the spraying end of the spray gun 2 has a swinging degree of freedom by means of the swing assembly 10. The distance between the spraying end of the spray gun 2 and the heat insulation pipe 4 is adjustable by means of its swinging degree of freedom.

[0043] By adjusting the distance between the spraying end of the spray gun 2 and the surface of the insulation pipe 4, it can not only adapt to insulation pipes 4 with different diameters, but also ensure that the spray gun 2 is at the optimal spraying distance each time the adhesive layer 601 is sprayed, since multiple layers of adhesive layer 601 need to be sprayed. After each layer of adhesive layer 601 is sprayed, the distance between the current insulation layer 6 and the spraying end of the spray gun 2 will be reduced, which may cause the spraying end of the spray gun 2 to come into contact with the current insulation layer 6.

[0044] like Figure 3-4 As shown, the swing assembly 10 includes a fixed block 1001, a transmission gear set, and a rotating gear ring 1002. The fixed block 1001 is fixedly connected to the fixed collar 8. The fixed end of the spray gun 2 is fixedly connected to the hinge shaft 1003 and hinged to the groove on the surface of the fixed block 1001 by means of the hinge shaft 1003. The rotating gear ring 1002 is coaxially arranged with the fixed collar 8 and has a degree of freedom of rotation. The inner wall of the rotating gear ring 1002 is provided with teeth. The end of the hinge shaft 1003 is connected to the rotating gear ring 1002 by means of the transmission gear set. The hinge shaft 1003 rotates synchronously with the rotation of the rotating gear ring 1002 and drives the spray gun 2 to swing.

[0045] When the rotating gear ring 1002 of the present invention rotates, it can synchronously drive all the hinge shafts 1003 to rotate through the transmission gear set, thereby driving all the spray guns 2 to swing synchronously, avoiding the problem of inconsistent angles and spacing caused by manual adjustment of a single set of spray guns 2, and ensuring the uniformity of circumferential spraying of the insulation pipe 4.

[0046] like Figure 4 As shown, the transmission gear set includes a driven gear 1004, a reversing bevel gear 1005, and a transmission shaft 1006 sleeved with the driven gear 1004. The driven gear 1004 meshes with the teeth of the rotating gear ring 1002. The reversing bevel gear 1005 is provided with two sets that mesh with each other. One set of reversing bevel gear 1005 is connected to the transmission shaft 1006, and the other set of reversing bevel gear 1005 is connected to the hinge shaft 1003. The driven gear 1004 drives the hinge shaft 1003 to rotate by means of the reversing bevel gear 1005.

[0047] Two sets of meshing bevel gears 1005 convert the horizontal power of the drive shaft 1006 into the vertical power of the hinge shaft 1003, driving the spray gun 2 to swing. In addition, the drive shaft 1006 and the fixed block 1001 are connected by bearings to prevent the driven gear 1004 from deviating during the rotation of the rotating gear ring 1002.

[0048] In addition, the rotating gear ring 1002 is also connected to the drive motor 11 and the reducer. When the drive motor 11 stops, the resistance of the reducer prevents the rotating gear ring 1002 from rotating on its own.

[0049] like Figure 5 As shown, the winding mechanism 5 includes a support collar 501 and a rotating collar 502 rotatably connected to the inner side of the support collar 501. Both the support collar 501 and the rotating collar 502 are coaxially arranged with the fixed collar 8. The support collar 501 and the fixed collar 8 are coaxially arranged on the movable seat 3. The side of the rotating collar 502 is provided with a winding wheel 503 for storing the fiber web. The fiber web on the winding wheel 503 is spirally wound along the axial direction of the insulation pipe 4 by means of the rotation of the rotating collar 502 and the translation of the movable seat 3.

[0050] The spiral winding method ensures that the fiber web evenly covers the surface of the adhesive layer 601, avoiding local missed winding or excessive overlap, and ensuring full bonding between the reinforcing layer 602 and the adhesive layer 601.

[0051] like Figure 1-2 As shown, both sides of the fixing collar 8 are provided with a net winding mechanism 5.

[0052] The mesh wrapping mechanism 5 on both sides can adapt to the reciprocating spraying of the spray gun 2. When the next layer of adhesive 601 is sprayed, the moving seat 3 does not need to be reset, which improves the spraying efficiency of the insulation layer 6.

[0053] The fiber web is a nylon fiber web with a pore size of 1-3 cm.

[0054] An operation method for a spraying system for a polyurethane insulation layer 6 on an insulation pipe 4 includes the following steps:

[0055] S1. Connect the two ends of the insulation pipe 4 to the rotating rollers 9 on both sides of the frame 1 respectively, and adjust the angle of the spray gun 2 so that the spraying end of the spray gun 2 faces the insulation pipe 4.

[0056] S201. Open the movable seat 3 and the winding mechanism 5, and move it from one end of the insulation pipe 4 to the other end;

[0057] S202, Multiple sets of spray guns 2 move together with the moving base 3 and spray polyurethane onto the insulation pipe 4 to form the upper adhesive layer 601;

[0058] S203, the fiber web is spirally wound onto the surface of the upper adhesive layer 601 along with the winding mechanism 5 and the movable seat 3 to form the upper reinforcing layer 602;

[0059] S204. Wait for the upper adhesive layer 601 to foam and overflow along the mesh of the upper reinforcing layer 602. After the upper adhesive layer 601 solidifies, it forms an upper thermal insulation layer together with the upper reinforcing layer 602.

[0060] S301, the movable seat 3 moves in the opposite direction, and the spray gun 2 sprays polyurethane onto the upper insulation layer surface to form the lower adhesive layer 601;

[0061] S302, the fiber web is spirally wound onto the surface of the lower adhesive layer 601 along with the winding mechanism 5 and the movable seat 3 to form the lower reinforcing layer 602;

[0062] S303, wait for the lower adhesive layer 601 to foam and overflow along the mesh of the lower reinforcement layer 602. After the lower adhesive layer 601 solidifies, it forms a lower insulation layer together with the lower reinforcement layer 602.

[0063] S4. Repeat steps S2-S3, and the multi-level insulation layers together form the insulation layer 6 of the insulation pipe 4.

[0064] When feeding the insulation pipe 4, first remove a set of rotating rollers 9 with the help of clamping seat 12, and then hoist the insulation pipe 4 in by means of hoisting. After aligning the two ends of the insulation pipe 4 with another set of rotating rollers 9, move clamping seat 12 to insert the removed rotating rollers 9 into the pipe opening of the insulation pipe 4 to complete the feeding and clamping process. The disassembly process is the reverse.

Claims

1. A method for operating a spraying system for a polyurethane insulation layer on a thermal insulation pipe, the spraying system comprising a frame (1) and a spray gun (2) mounted on the frame (1) for spraying polyurethane, characterized in that, Multiple sets of spray guns (2) are arranged around the periphery of the insulation pipe (4). A movable seat (3) is also provided on the frame (1). A wire wrapping mechanism (5) is provided on the movable seat (3). The spray gun (2) and the wire wrapping mechanism (5) have the freedom to move back and forth along the axial direction of the insulation pipe (4) by means of the movable seat (3). The fiber web is wrapped onto the adhesive layer formed by polyurethane spraying by means of the wire wrapping mechanism (5). A guide rail (7) is provided on the frame (1). The movable seat (3) and the guide rail (7) are slidably engaged and It has the freedom to translate in the horizontal direction. The moving base (3) is also provided with a ring-shaped fixing collar (8). The fixing collar (8) is sleeved on the outside of the heat insulation pipe (4). The fixed end of the spray gun (2) is connected to the fixing collar (8). The two sides of the frame (1) are also symmetrically provided with rotating rollers (9) that rotate with the frame. One rotating roller (9) is connected to a drive motor (11). The other rotating roller (9) is set on a clamping seat (12) that is slidably connected to the guide rail (7). The heat insulation pipe (4) The rotating roller (9) forms a rotation and a relative spiral motion with respect to the spray gun (2). The fixed end of the spray gun (2) is hinged to the inner wall of the fixed collar (8) by means of the swing assembly (10). The spraying end of the spray gun (2) has a swing freedom by means of the swing assembly (10). The distance between the spraying end of the spray gun (2) and the heat insulation pipe (4) is adjustable by means of its swing freedom. The winding mechanism (5) includes a support collar (501) and a rotating collar (502) rotatably connected to the inner side of the support collar (501). The supporting collar (501) and the rotating collar (502) are both coaxially arranged with the fixed collar (8). The supporting collar (501) and the fixed collar (8) are coaxially arranged on the movable seat (3). The rotating collar (502) has a winding wheel (503) for storing the fiber web on its side. The fiber web on the winding wheel (503) is spirally wound along the axial direction of the heat insulation pipe (4) by means of the rotation of the rotating collar (502) and the translation of the movable seat (3). Both sides of the fixed collar (8) are provided with a web winding mechanism (5). The operation method of the spraying system includes the following steps: S1. Connect the two ends of the insulation pipe (4) to the rotating rollers (9) on both sides of the frame (1) respectively, and adjust the angle of the spray gun (2) so that the spraying end of the spray gun (2) faces the insulation pipe (4). S201, Open the movable seat (3) and the winding mechanism (5), and move it from one end of the heat preservation pipe (4) to the other end; S202, Multiple sets of spray guns (2) move together with the moving seat (3) and spray polyurethane onto the insulation pipe (4) to form an upper adhesive layer; S203, the fiber web winding mechanism (5) and the moving seat (3) are spirally wound onto the surface of the upper adhesive layer to form the upper reinforcement layer; S204. Wait for the upper adhesive layer to foam and overflow along the mesh of the upper reinforcement layer. After the upper adhesive layer solidifies, it forms an upper thermal insulation layer together with the upper reinforcement layer. S301, the moving seat (3) moves in the opposite direction, and the spray gun (2) sprays polyurethane onto the upper insulation layer surface to form the lower adhesive layer; S302, the fiber web winding mechanism (5) and the moving seat (3) are spirally wound onto the surface of the lower adhesive layer to form the lower reinforcement layer; S303. Wait for the lower adhesive layer to foam and overflow along the mesh of the lower reinforcement layer. After the lower adhesive layer solidifies, it forms a lower insulation layer together with the lower reinforcement layer. S4. Repeat steps S201-S303, and the multi-level insulation layers together form the insulation layer (6) of the insulation pipe (4).

2. The operation method of the polyurethane insulation layer spraying system for thermal insulation pipes according to claim 1, characterized in that, The swing assembly (10) includes a fixed block (1001), a transmission gear set, and a rotating gear ring (1002). The fixed block (1001) is fixedly connected to the fixed collar (8). The fixed end of the spray gun (2) is fixedly connected to the hinge shaft (1003) and hinged to the groove on the surface of the fixed block (1001) by means of the hinge shaft (1003). The rotating gear ring (1002) is coaxially arranged with the fixed collar (8) and has a degree of freedom of rotation. The inner wall of the rotating gear ring (1002) is provided with teeth. The end of the hinge shaft (1003) is connected to the rotating gear ring (1002) by means of the transmission gear set. The hinge shaft (1003) rotates synchronously with the rotation of the rotating gear ring (1002) and drives the spray gun (2) to swing.

3. The operation method of the polyurethane insulation layer spraying system for thermal insulation pipes according to claim 2, characterized in that, The transmission gear set includes a driven gear (1004), a reversing bevel gear (1005), and a transmission shaft (1006) sleeved with the driven gear (1004). The driven gear (1004) meshes with the teeth of a rotating gear ring (1002). The reversing bevel gear (1005) is provided with two sets that mesh with each other. One set of reversing bevel gears (1005) is connected to the transmission shaft (1006), and the other set of reversing bevel gears (1005) is connected to the hinge shaft (1003). The driven gear (1004) drives the hinge shaft (1003) to rotate by means of the reversing bevel gear (1005).

4. The operation method of the polyurethane insulation layer spraying system for thermal insulation pipes according to claim 1, characterized in that, The fiber web is a nylon fiber web with a pore size of 1-3 cm.

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