How to rehabilitate existing pipes

Abstract

To prevent unmating and insufficient tensioning of joints by maintaining a distance between an imaging moving body and a cone part at a certain level with a simple configuration in an expanded pipe for a rehabilitation pipe installed in an existing pipe, thereby ensuring that a cone length is properly controlled.SOLUTION: After a helical rehabilitation pipe 3 made of a belt-like member 10 is manufactured to have a diameter smaller than that of an existing pipe 1, a cutting wire 41 interposed at a joint 15 between adjacent edges of the belt-like member 10 is removed. A circumferential length of a cut portion of the rehabilitation pipe 3 is gradually expanded while sequentially cutting a part 14b of the joint in a winding direction. An imaging moving body 20 is connected to a wire part 41b to be pulled, of the cutting wire 41 through a traction rope 30. The imaging moving body 20 is positioned so that a camera of the imaging moving body 20 captures a cone part 3c being expanded from an expanded tube part 3b side of the rehabilitation pipe 3, and the imaging moving body 20 is pulled by a pull force that pulls the wire part 41b to be pulled.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for rehabilitating an existing pipe such as an aged sewer pipe, and more particularly to a rehabilitation method for constructing a spiral-shaped rehabilitation pipe inside an existing pipe. [Background technology]

[0002] A method for rehabilitating an existing pipe, such as an aging sewer pipe, is known, in which a strip-shaped member (profile) is spirally wound around the inner circumference of the existing pipe and adjacent edges of the strip-shaped member, one turn apart, are joined by a concave-convex fit to construct a helical rehabilitating pipe (see Patent Document 1, etc.). For example, Patent Document 1 discloses a so-called expanding pipe manufacturing method. In this method, a cutting wire is inserted between the joints of the adjacent edges of the strip-shaped member, and a rehabilitating pipe is manufactured to a diameter smaller than the inner diameter of the existing pipe. The cutting wire is then withdrawn to sequentially cut portions of the joint in the winding direction. Simultaneously, a torsional force is applied to the rehabilitating pipe by, for example, supplying more strip-shaped member, thereby expanding the circumference of the cut portion. This results in the rehabilitating pipe being attached to the entire inner circumference of the existing pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-093547 Summary of the Invention [Problem to be solved by the invention]

[0004] In the expandable pipe manufacturing method described in Patent Document 1, when the rehabilitating pipe is expanded, a cone-shaped portion is formed between the original small-diameter portion and the expanded large-diameter portion. If the axial length of the cone portion (hereinafter referred to as "cone length") is too short, there is a risk of the joint coming loose. On the other hand, if the cone length is too long, there is a risk of insufficient adhesion.

[0005] One possible solution is to introduce a self-propelled imaging vehicle into the rehabilitating pipe, capture images of the cone section, determine the cone length from the images, and then adjust the cutting wire take-up speed and the strip-shaped material supply speed (pipe production speed). In this case, it is necessary to maintain a constant, accurate relative distance between the self-propelled imaging vehicle and the cone section. If the relative distance changes, the cone length cannot be accurately controlled. Furthermore, if the relative distance is too short, the attachment position of the large-diameter end of the cone section will be out of the frame of the camera image and will not be visible. If the relative distance is too long, the wire withdrawal position of the small-diameter end of the cone section will be too far away and will not be visible.

[0006] However, if multiple people share the tasks of operating the self-propelled imaging vehicle, taking in the cutting wire, and supplying the strip-shaped material, it is not easy for them to communicate with each other. In the first place, the inside of the rehabilitation pipe is dark, making it difficult to operate the self-propelled imaging vehicle, and it is not easy to run the self-propelled imaging vehicle while maintaining a constant relative distance from the cone. In view of such circumstances, the present invention aims to accurately manage the cone length and prevent disengagement and insufficient adhesion of the joint by reliably maintaining a constant distance between the imaging movable body and the cone portion in a so-called expanded pipe manufacturing device using a simple configuration. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a method for rehabilitating an existing pipe, which comprises: forming a spiral rehabilitating pipe, which is made by spirally winding a strip-shaped member and joining adjacent edges that are one turn apart, to a diameter smaller than the inside diameter of the existing pipe; and then successively cutting portions of the joint in the winding direction by pulling out a cutting wire that has been interposed between the joints of the adjacent edges, thereby successively expanding the circumferential length of the rehabilitating pipe at the cut portions, a pulling wire portion of the cutting wire extending from the joint portion into the rehabilitation pipe is connected to an imaging moving body via a towing rope; The imaging mobile body is disposed so that the camera of the imaging mobile body photographs the cone portion being expanded from the expanded pipe portion side of the rehabilitation pipe, The imaging moving body is pulled by a pulling force that pulls the pulled wire portion toward the unexpanded pipe portion of the rehabilitating pipe.

[0008] According to this rehabilitation method, as the pulled wire portion is pulled, the imaging mobile body is pulled and moved toward the unexpanded pipe portion. The distance between the camera and the cone portion is determined by the length of the towing rope. Therefore, the imaging distance of the cone portion is always maintained constant. As a result, the cone length can be accurately managed, and disengagement of the joint and insufficient adhesion can be reliably prevented. The imaging mobile body does not require a drive mechanism or steering mechanism for self-propulsion, which simplifies the configuration of the imaging mobile body.

[0009] It is preferable that the towing rope is slidably connected to the wire portion to be taken up, so that the end of the towing rope connected to the wire portion to be taken up slides along the wire portion to be taken up as the wire portion to be taken up is taken up.

[0010] A take-off start wire is prepared, and the cutting wire or the take-off start wire is passed through a ring provided at the end of the towing rope, Next, the cutting wire and the take-off start wire are connected together, Thereafter, it is preferable to apply the pull-up force to the pull-up start wire. This allows the towing rope to be slidably connected to the take-up wire portion.

[0011] It is preferable that at least the surface layer of the ring is made of a light-emitting or light-reflecting material, so that even if the inside of the rehabilitation pipe is dark, the ring will glow, making it easy to confirm the position of the end of the tow rope in the captured image and allowing the cone length to be measured reliably. [Effects of the Invention]

[0012] According to the present invention, when expanding a rehabilitating pipe to be installed inside an existing pipe, the distance between the imaging moving body and the cone portion can be reliably kept constant with a simple configuration. As a result, the cone length can be accurately managed, and disengagement and insufficient adhesion of the joint can be prevented. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a method for rehabilitating an existing pipe according to one embodiment of the present invention, in a preparation stage for expansion after manufacturing an unexpanded rehabilitating pipe. [Figure 2] FIG. 2 is a front view showing the wires and rings in circle II of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the existing pipe rehabilitation method in the expansion step of the rehabilitating pipe. [Figure 4] Fig. 4(a) is a perspective cross-sectional view of the joint of the rehabilitating pipe before expansion, and Fig. 4(b) is a perspective cross-sectional view of the joint of the rehabilitating pipe after expansion. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <Existing pipe 1 and rehabilitation pipe 3> 1 and 3, an existing pipe 1 is rehabilitated by lining its inner periphery with a rehabilitation pipe 3. The existing pipe 1 to be rehabilitated is, for example, a sewer pipe buried underground, but the present invention is not limited to this and may also be a water supply pipe, an agricultural water pipe, a gas pipe, a hydroelectric power generation water pipe, a tunnel, etc. Both ends of the existing pipe 1 are connected to manholes 4, 4B.

[0015] <Belt-shaped member 10> As shown in Figure 4(a), the rehabilitation pipe 3 is composed of a strip-shaped member (profile) 10. The strip-shaped member 10 is made of a synthetic resin such as polyvinyl chloride (PVC) and is formed into a specific cross-sectional shape. Male and female mating portions 13, 14 are provided on both edges of the strip-shaped member 10 in the width direction.

[0016] <Existing pipe rehabilitation method> The existing pipe 1 is rehabilitated as follows. <Pipe manufacturing process> As shown in Figure 1, a push-type pipe making machine 8 is prepared and installed in the manhole 4 on the starting side. A strip-shaped member 10 is sequentially unwound from a drum 7 on the ground and supplied to the pipe making machine 8. In the pipe making machine 8, the strip-shaped member 10 is spirally wound and adjacent mating portions 13, 14 that are offset by one turn are joined by a concave-convex fit (Figure 4(a)), thereby sequentially producing a rehabilitated pipe 3. A joint 15 is formed by the mating mating portions 13, 14. The joint 15 extends spirally over the entire length of the rehabilitated pipe 3. At this point, the rehabilitated pipe 3 has a smaller diameter than the inner diameter of the existing pipe. The produced rehabilitating pipe 3 is sequentially pushed into the interior of the existing pipe 1 by the push-type pipe making machine 8.

[0017] <Cutting wire intervening process> As shown in FIGS. 1 and 4( a ), during the pipe making process, a cutting wire 41 is introduced into the pipe making machine 8 from the starting manhole 4 and interposed between the fitting portions 13 , 14 of the joint portion 15 .

[0018] Specifically, as shown in Figure 1, a cutting wire 41 is unwound from a wire unwinding roll 44 mounted on a ground work vehicle 5. Then, prior to the start of the pipe making process by the main push type pipe making machine 8, when unwinding the rehabilitating pipe 3 from the strip-shaped member 10, the cutting wire 41 is sandwiched between the fitting portions 13, 14 with the tip portion 41e of the cutting wire 41 slightly projecting from the tip surface of the strip-shaped member 10 in the strip length direction.

[0019] After producing two to three turns of the rehabilitating pipe 3 using the push-type pipe producing machine 8, the pipe producing machine 8 is stopped temporarily, and the tip portion 41e is pulled out toward the pipe producing machine 8, i.e., toward the side opposite the extended front end portion 3f of the rehabilitating pipe 3. At this time, the tip portion 41e of the cutting wire 41 cuts into the base portions of some of the ridges 14b in the male fitting portion 14 of the belt-shaped member 10, approximately 5 centimeters from the tip surface of the belt-shaped member 10 (see Figure 4(b)). The tip portion 41e of the cutting wire 41 is clamped in the cut. If making the cuts manually would be too much of a burden, a cutter such as a pipe saw may be used to make cuts in the ridges 14b before unwinding begins. After two or three turns of the rehabilitating pipe 3 have been made, the tip 41e of the cutting wire 41 may be pulled out and clamped in the cuts made beforehand.

[0020] <Wire connection process for starting collection> In addition, the take-up start wire 42 is unwound from the wire take-up winch 43 of the ground work vehicle 5, passed through the starting manhole 4B, and passed through the rehabilitation pipe 3, and connected to the tip portion 41e of the cutting wire 41. The connecting process may be performed after the operator manually pulls the tip portion 41e toward the pipe making machine 8, or may be performed before pulling it out. If the connecting process is performed before pulling it out, after connecting, the driving force of the wire take-up winch 43 can be used to pull the tip portion 41e toward the pipe making machine 8 and make a cut in the protrusion 14b. Preferably, a swivel joint 45 is provided at the connection between the cutting wire 41 and the take-up start wire 42 or at the take-up start wire 42 .

[0021] Typically, the pulling out, connecting, and unwinding operations are carried out inside the starting manhole 4. If the entrance 4a of the starting manhole 4 is large enough, these operations can be carried out on the ground, and then the push-type pipe making machine 8 incorporating several rolls of rehabilitating pipe 3 can be carried into the starting manhole 4 from the entrance.

[0022] Thereafter, the pipe is produced using the push-type pipe producing machine 8. As a result, a cutting wire 41 is embedded in the spiral joint 15 of the produced rehabilitating pipe 3 (FIG. 4(a)). In addition, as the rehabilitating pipe 3 is extended, a take-up start wire 42 is sent through the rehabilitating pipe 3 toward the arrival side manhole 4B. During pipe making, the rehabilitation pipe 3 is rotated and extended toward the arrival manhole 4. At this time, the swivel joint 45 can prevent twisting of the take-up start wire 42.

[0023] In this way, pipe is produced up to the manhole 4B on the arrival side, and a rehabilitating pipe 3 (unexpanded pipe section 3a) having a smaller diameter than the existing pipe 1 is installed over the entire length of the existing pipe 1. At this stage, the cutting wire 41 is wound spirally along the strip-shaped member 10 over the entire length of the rehabilitating pipe 3. The tip portion 41e of the cutting wire 41 is pulled out slightly from the front extension end of the rehabilitating pipe 3, i.e., the arrival end 3f (the left end in Figure 1), and a pull-up start wire 42 is connected to this. <Rotation prevention process> Preferably, the end portion 3f of the rehabilitating pipe 3 on the arrival side is fixed to the existing pipe 1 by a fixing means (not shown) to prevent rotation.

[0024] Separately, an imaging moving body 20 and a towing rope 30 are prepared. <Imaging moving object 20> The imaging mobile body 20 includes a towing dolly 21 and a camera 22. The towing dolly 21 includes a base 21a and wheels 21b. The towing dolly 21 does not require a traveling power source such as a motor or a steering mechanism. A camera 22 is mounted on the towing dolly 21. The imaging direction of the camera 22 is directed toward the front of the towing-type traveling body dolly 1. The camera 22 is equipped with a light 23 that illuminates the imaging direction. The imaging vehicle 20 may be a self-propelled camera vehicle having a driving power and steering mechanism, and may be used with the wheels free to rotate by disengaging the clutch. <Image capture moving object placement process> The imaging moving body is inserted into the access manhole 4B, and the imaging moving body 20 is placed inside the rehabilitation pipe 3 with the camera 22 facing the starting side.

[0025] <Towing rope 30> The proximal end of a towing rope 30 is fastened to a towing hook 24 at the front of the towing carriage 21. A swivel joint 32 is provided on the towing rope 30. A ring 31 is provided at the tip of the towing rope 30. Preferably, at least the surface layer of the ring 31 is made of a light-emitting material or a light-reflecting material.

[0026] The length of the towing rope 30 is determined by the distance required from the camera 22 to the attachment position (the large-diameter end of the cone portion 3c (FIG. 3) described later) so that the attachment position is included in the image captured by the camera 22, and the axial length L of the cone portion 3c described later. 3c (Fig. 3). Preferably, the length of the towing rope 30 is determined by the required separation distance and the axial length L 3c The required separation distance is set to about the total length of the maximum value of the preferred range of the axial length L of the cone portion 3c described later. 3c The preferred range of the axial length L of the cone portion 3c is generally about 1.0 meter to 2.5 meters. 3c Even when the distance is the maximum value (2.5 meters) of the preferred range, the camera 22 must be spaced away from the cone portion 3c so that the entire cone portion 3c is included in the image captured by the camera 22. Therefore, the preferred length of the towing rope 30 is about 1 + 2.5 = 3.5 meters.

[0027] <Rope connection process> As shown in Fig. 2, the tip portion 41e of the cutting wire 41 or the haul-start wire 42 is passed through the ring 31 at the tip of the towing rope 30. This allows the towing rope 30 to be slidably connected to the haul-start wire 42 and the hauled wire portion 41b. The rope connecting process may be performed in the starting manhole 4 before the pipe making process or during the haul-start wire connecting process on the ground, or in the arrival manhole 4B after the pipe making process. That is, the cutting wire 41 or the haul-start wire 42 may be passed through the ring 31 in advance prior to connecting the haul-start wire 42. Alternatively, after the extension front end 3f of the rehabilitation pipe 3 reaches the arrival manhole 4B, the cutting wire 41 and the haul-start wire 42 may be temporarily separated within the arrival manhole 4B, and one of the cutting wire 41 and the haul-start wire 42 may be passed through the ring 31, and then the cutting wire 41 and the haul-start wire 42 may be reconnected. In either case, the connecting work can be performed within the manholes 4, 4B within the reach of the worker. Even if the rope connection process is carried out in the starting manhole 4 before the pipe making process, the work of connecting the proximal end of the towing rope 30 to the towing cart 21 is carried out in the arrival manhole 4B after the pipe making process. As a result, the imaging moving body 20 is connected to the wires 41 and 42 via the towing rope 30.

[0028] <Pick-up process> 3, the take-up start wire 42 is then taken up by the wire take-up winch 43. That is, a take-up force is applied to the take-up start wire 42 and ultimately to the cutting wire 41. As a result, the taken-up wire portion 41b including the tip portion 41e of the cutting wire 41 is taken up toward the starting side (the unexpanded pipe portion side) of the rehabilitating pipe 3. Furthermore, the intervening wire portion 41a in the joint portion 15 of the cutting wire 41 is successively drawn from the reaching side of the rehabilitating pipe 3 into the inside of the rehabilitating pipe 3, incorporated into the taken-up wire portion 41b, and taken up toward the starting side.

[0029] <Cutting process> 4(b), at this time, a part of the ridge 14b (part of the joint 15) in the male fitting part 14 is cut from its base by the folded wire part 41c between the intervening wire part 41a and the taken-up wire part 41b. Therefore, the binding force between the fitting parts 13, 14 at the joint 15 is weakened, and the fitting parts 13, 14 become able to slide relative to each other in the winding direction. 3, the folded wire portion 41c is moved spirally along the winding direction toward the starting-side end portion 3e of the rehabilitating pipe 3. Accordingly, the ridges 14b are cut off successively in the winding direction.

[0030] <Expansion process> 3, in parallel with this, the pipe making machine 8 is driven to further supply the strip-shaped member 10 to the rehabilitating pipe 3. This applies a torsional force to the rehabilitating pipe 3, causing the small-diameter unexpanded pipe section 3a from the starting end 3e of the rehabilitating pipe 3 to rotate from the turned-back wire section 41c. The circumferential length of the section of the rehabilitating pipe 3 where the joint 15 has been cut, from the turned-back wire section 41c to the stopped arrival end 3f, is gradually expanded (expanded in diameter).

[0031] Specifically, the rehabilitating pipe 3 has a cone section 3c that expands in diameter from the folded wire section 41c toward the destination side. In the cone section 3c, the fitting sections 13, 14 of the joint 15 slide relative to each other along the winding direction. The section of the rehabilitating pipe 3 from the cone section 3c to the destination end 3f becomes the expanded pipe section 3b. The expanded pipe section 3b is attached around the entire inner periphery of the existing pipe 1. The outer diameter of the expanded pipe section 3b is larger than that of the unexpanded pipe section 3a and is a constant diameter equal to the inner diameter of the existing pipe 1.

[0032] <Filming process> The imaging mobile body 20 is placed inside the rehabilitating pipe 3 with the camera 22 facing from the expanded pipe section 3b side of the rehabilitating pipe 3 toward the starting side. The camera 22 captures an image of the cone section 3c being expanded. The captured image is sent via a signal cable 6b to the image control unit 6 of the ground-based operating vehicle 5B and displayed on a monitor.

[0033] <Cone length measurement process> From the captured image displayed on the monitor, the axial length L of the cone part 3c 3c The cone length (length) is measured. A ring 31 is disposed near the folded wire portion 41c, and the ring 31 emits light and reflects the illumination light of the light 23, making it easy to determine the position of the small diameter end of the cone portion 3c. Even if the inside of the rehabilitation pipe 3 is dark, or even if the folded wire portion 41c and the ring 31 are underwater while the sewer is in service, the position of the small diameter end of the cone portion 3c can be reliably determined. Since the large diameter end of the cone portion 3c is located closer to the camera 22 than the small diameter end, its position can be easily confirmed from the captured image. 3c can be measured accurately.

[0034] <Cone length adjustment process> Based on the measurement results, the cone length L 3c The wire take-up winch 43 is operated to adjust the take-up speed of the cutting wire 41, and the pipe making machine 8 is operated to adjust the supply speed of the strip-shaped material 10 so that the cone length L 3c By controlling the length L, it is possible to prevent the joint 15 at the small diameter end of the cone portion 3c from coming off, and the large diameter end of the cone portion 3c and the expanded pipe portion 3b from insufficiently adhering to the existing pipe 1. 3c This allows for reliable management and prevents loose fitting and insufficient adhesion.

[0035] <Towing process> As described above, as the turning-back wire portion 41c is moved toward the starting end 3e by the pulling of the cutting wire 41, the ring 31 connected to the taken-up wire portion 41b near the turning-back wire portion 41c is also moved toward the starting end 3e. As a result, the imaging moving body 20 is pulled via the pulling rope 30 and moved toward the unexpanded tube portion 3a. In other words, the imaging moving body 20 is pulled by the pulling force on the cutting wire 41. Therefore, the distance between the camera 22 and the cone portion 3c is determined by the length of the pulling rope 30 and is always kept constant. This makes it possible to reliably maintain a constant shooting distance for the cone portion 3c. As a result, the cone length L 3c This allows for accurate management of the joint 15 and reliably prevents disengagement and insufficient adhesion of the joint 15. Furthermore, the construction quality of the expanded pipe for the rehabilitating pipe 3 can be improved.

[0036] The imaging mobile body 20 does not require a drive mechanism or a steering mechanism for self-propulsion, and can be made to have a simple configuration. By providing the towing rope 30 with the swivel joint 32, even if the folded wire portion 41c moves spirally along the winding direction, the towing rope 30 can be prevented from twisting. The worker does not need to operate the traveling of the imaging mobile body 20, and can concentrate only on operating the wire take-up winch 43 and the pipe making machine 8. This simplifies the expanded pipe making work, and also reduces the number of personnel required. In this way, the circumferential length is expanded over the entire area of ​​the rehabilitating pipe 3, and the entire area of ​​the rehabilitating pipe 3 becomes an expanded pipe portion 3b that adheres to the inner circumferential surface of the existing pipe 1.

[0037] The pulling process is continued until the imaging moving body 20 approaches the starting manhole 4. Pulling is terminated when the folded wire portion 41c comes very close to the pipe making machine 8 (just before the pulled wire 41b interferes with the engaging roller of the pipe making machine 8). Next, a finishing process is carried out in which the starting end 3e of the rehabilitation pipe 3 is attached to the inner circumference of the existing pipe 1. Thereafter, the take-up wire 41b is cut, the ring 31 is separated from the take-up wire 41b, and the imaging mobile body 20 is moved from near the starting manhole 4 inside the rehabilitation pipe 3 to the arrival manhole 4B. The imaging mobile body 20 may be returned to the arrival manhole 4B side by pulling on the cable 6b. Then, a worker retrieves the imaging mobile body 20 from the arrival manhole 4B.

[0038] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the wheels 21b of the imaging mobile body 20 do not have to rotate freely, and furthermore, the wheels 21b may be omitted from the imaging mobile body 20. The imaging mobile body 20 may be loaded onto a dedicated towing carriage, and the towing carriage and the towed wire portion 41b may be connected by a towing rope 30. The imaging mobile body 20 may be slidably towed by the towing force of the towed wire portion 41b. [Industrial Applicability]

[0039] The present invention can be applied to, for example, the rehabilitation of deteriorated sewer pipes. [Explanation of symbols]

[0040] 1 Existing pipes 3 Rehabilitation pipe 3a Unexpanded pipe section 3b Expanded pipe section 3c Cone section 3e Starting end 3f Reaching side end 8 Pipe making machine 10. Belt-shaped member 13,14 Fitting part 14b Convex strip (part of joint) 15 Joint 20 Imaging Mobile Object 21 Traction trolley 22 Camera 23 Light 24 Tow hook 30 Tow rope 32 Swivel joint 31 Ring 41 Cutting Wire 41a Intervening wire part 41b Wire to be taken up 41c Folded wire part 41e Tip part 42 Wire for starting take-over 43 Wire take-up winch

Claims

1. A method for rehabilitating an existing pipe, comprising the steps of: winding a strip-shaped member in a spiral shape and joining adjacent edges that are one turn apart to produce a spiral rehabilitating pipe with a diameter smaller than the inside diameter of the existing pipe; and then, by pulling out a cutting wire that has been placed at the joints between the adjacent edges, sequentially cutting portions of the joints in the winding direction, thereby sequentially expanding the circumferential length of the rehabilitating pipe at the cut portions; a pulling wire portion of the cutting wire extending from the joint portion into the rehabilitation pipe is connected to an imaging moving body via a towing rope; The imaging mobile body is disposed so that the camera of the imaging mobile body photographs the cone portion being expanded from the expanded pipe portion side of the rehabilitation pipe, A method for rehabilitating an existing pipe, characterized in that the imaging moving body is pulled by a pulling force that pulls the wire portion to be pulled toward the unexpanded pipe portion of the rehabilitating pipe.

2. 2. The method for rehabilitating an existing pipe according to claim 1, wherein the towing rope is slidably connected to the to-be-taken wire portion.

3. A take-off start wire is prepared, and the cutting wire or the take-off start wire is passed through a ring provided at the end of the towing rope; Next, the cutting wire and the take-off start wire are connected together, 3. The method for rehabilitating an existing pipe according to claim 2, wherein the pulling force is then applied to the pulling start wire.

4. 4. The method for rehabilitating an existing pipe according to claim 3, wherein at least the surface layer of the ring is made of a light-emitting material or a light-reflecting material.

Images