Rehabilitation methods for existing pipes

Abstract

To smoothly and reliably expand an expansion end portion of a rehabilitation pipe in an expander pipe manufacturing method.SOLUTION: There is provided a rehabilitation method of an existing pipe, wherein a helical rehabilitation pipe 3 is manufactured to have a diameter smaller than that of an existing pipe 1 by winding a belt-shaped member 10 into a spiral state, and then a peripheral length of the rehabilitation pipe 3 is expanded by sequentially forming a binding weakened pipe portion 31 from a second side to a first side in a pipe axis direction. When a cone portion 32 undergoing expansion deformation reaches near a pipe making machine 20, a binding ability between adjacent edge portions 13 and 14 is weakened by applying cutting or the like to a protruding strip 13b before bonding. A weakly binding pipe portion 34 is formed from the belt-shaped member 10 including the edge portions 13 and 14 that are obtained through the preliminary weakening process and is fed into a small-diameter pipe portion 30. The weakly binding pipe portion 34 and the binding weakened pipe portion 31 are merged. Thereafter, the pipe making machine 20 is separated from the rehabilitation pipe 3.SELECTED DRAWING: Figure 6(b)

Description

Technical Field

[0001] The present invention relates to a method for rehabilitating an existing pipe by constructing a spiral-shaped rehabilitation pipe along the inner circumference of an aging existing pipe by means of a so-called expander (expansion) pipe manufacturing method. In particular, it relates to a method for expanding or finishing the expansion of an expansion terminal portion near a pipe manufacturing machine for expansion in the rehabilitation pipe.

Background Art

[0002] A method of rehabilitating an existing pipe by constructing a spiral-shaped rehabilitation pipe inside an aging existing pipe such as a sewer pipe is known (see, for example, Patent Document 1). The spiral-shaped rehabilitation pipe is constructed by winding a belt-shaped member in a spiral shape and joining adjacent edge portions that are one turn apart.

[0003] Patent Document 1 discloses a so-called expander (expansion) pipe manufacturing method as one method for constructing a spiral-shaped rehabilitation pipe. Specifically, a rehabilitation pipe having a smaller diameter than the inner diameter of the existing pipe is manufactured while interposing a wire for weakening restraint between the adjacent edge portions of the belt-shaped member. Thereafter, by pulling out the wire for weakening restraint, one of the ridges for concave-convex fitting of the edge portion of the belt-shaped member is cut along the winding direction from the reaching end side to the starting end side of the rehabilitation pipe. In parallel with this, the belt-shaped member is further supplied by the pipe manufacturing machine at the starting side manhole, and torsional force is applied to the rehabilitation pipe to expand (increase the diameter) the circumference of the portion where the cutting has been made. As a result, the rehabilitation pipe is attached over the entire circumference of the inner peripheral surface of the existing pipe.

[0004] In the construction of the expander pipe manufacturing method, it is important to manage the length of the cone portion that expands in diameter from the unexpanded small-diameter pipe portion to the expanded large-diameter pipe portion in the rehabilitation pipe. If the cone portion is too long, poor adhesion to the inner peripheral surface of the existing pipe occurs. On the other hand, if the cone portion is too short, buckling (breakage of the concave-convex fitting between adjacent edge portions) occurs between the unexpanded small-diameter pipe portion and the cone portion. In particular, at the expansion terminal portion near the starting side manhole in the rehabilitation pipe, since the starting side manhole is narrow and the pipe manufacturing machine can only be separated from the pipe opening of the existing pipe by about 200 mm, it is impossible to ensure a sufficient length of the cone portion, and buckling is likely to occur.

[0005] In Patent Document 1, in order to prevent buckling at the expanded end portion, the expansion process is performed up to that point, after which the pipe-making machine is stopped, and the restraining wire is pulled back to the position closest to the pipe-making machine, thereby cutting the protrusion up to that position. At that position, the rehabilitated pipe is cut all the way around, and the pipe-making machine is released from the rehabilitated pipe. After that, the released end of the rehabilitated pipe is allowed to expand naturally. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-115750 (Figure 4(a)) [Overview of the project] [Problems that the invention aims to solve]

[0007] However, at the position immediately adjacent to the pipe-making machine, the pulling angle of the restraint-reducing wire is steep, and the angle difference with respect to the pipe axis is large, raising concerns that the restraint-reducing wire may break or get caught in the pipe-making machine. In view of these circumstances, the present invention aims to smoothly and reliably expand the expanded end portion of a rehabilitation pipe in an expander pipe construction method. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention provides a method for rehabilitating an existing pipe, comprising a pipe manufacturing step in which a spiral-shaped rehabilitated pipe is formed by spirally winding a strip-shaped member and joining adjacent edge portions that are offset by one full turn, and the pipe manufactured to a diameter smaller than the inner diameter of the existing pipe and installed inside the existing pipe, and a restraint weakening step in which the restraint force between the adjacent edge portions is sequentially weakened along the winding direction from the second side in the pipe axis direction of the rehabilitated pipe toward the first side, thereby forming a restraint weakened pipe portion, and a subsequent strip portion of the strip-shaped member that follows the pipe end on the first side of the rehabilitated pipe is fed into the rehabilitated pipe by a pipe manufacturing machine, thereby expanding the circumference of the restraint weakened pipe portion, A process performed from the time the cone section, which expands in diameter from the unexpanded small-diameter section to the expanded large-diameter section of the rehabilitated pipe, reaches near the pipe-making machine, comprising a pre-weakening step that weakens the restraining force between adjacent edge sections before joining, A weak-restraint pipe-making process in which the adjacent edge portions that have undergone the aforementioned pre-weakening process are joined together by the pipe-making machine and fed into the small-diameter pipe section, A merging process is performed to merge the weakly restrained pipe portion manufactured by the weakly restrained pipe manufacturing process in the small-diameter pipe section with the restrained weakened pipe portion. Subsequently, a cutting step is performed to separate the pipe-making machine from the rehabilitated pipe, It is characterized by having the following features.

[0009] The aforementioned pre-weakening step and the aforementioned weak-restraint pipe manufacturing step result in the formation of a weakly restrained pipe portion in at least the first side portion of the small-diameter pipe section. The cone portion, including the weakly restrained pipe section, and the weakened restraint pipe section merge, eliminating the unreinforced portion of the small-diameter pipe section. Therefore, after the merger, there is no need to perform the restraint weakening process. Consequently, there is no need to retrieve the restraint weakening wire for post-pipe manufacturing, for example. Thus, the risk of the restraint weakening wire breaking or getting caught in the pipe manufacturing machine is eliminated. Subsequently, the first end of the weakly constrained pipe portion is released by the cutting process. This allows the entire expanded end portion of the rehabilitation pipe, including the cone portion at the junction and the weakly constrained pipe portion, to expand naturally. As a result, the expanded end portion can be expanded smoothly and reliably without causing buckling.

[0010] Preferably, in the pipe manufacturing process, multiple helical joints, including a first helical joint and a second helical joint, are formed by joining the adjacent edge portions together. In the aforementioned restraint weakening step, the joined state of the first helical joint portion of the helical joint is maintained while the joint of the second helical joint portion is released. This ensures that the restraining force between adjacent edge portions is reliably weakened. Therefore, the adjacent edge portions of the cone portion can be reliably slid along the winding direction. The joined state of the first helical joint portion is reliably maintained. Preferably, in the pre-weakening step, the subsequent band portion or the portion of the pipe end before joining that will become the second helical joint portion is made unjoinable. This ensures that the restraining force between the adjacent edge portions of the subsequent band portion is reliably weakened. Moreover, the same second helical joint portion that is targeted for release in the restraint weakening step can be made unjoinable. Preferably, in the weakened-restraint pipe manufacturing process, only the first helical joint portion of the first and second helical joint portions is formed. By making the portion that will become the second helical joint portion unjoinable through the pre-weakening process, the second helical joint portion can not be formed. By maintaining the joining ability of the portion that will become the first helical joint portion, pipe manufacturing can be carried out even after the pre-weakening process. Preferably, in the merging step, the starting end of the portion that cannot be joined is merged with the ending end of the portion that has been released from joining. This makes the weakly constrained pipe portion and the weakened constrained pipe portion continuous, allowing the entire area of ​​the first side expanded end portion of the rehabilitation pipe to expand naturally.

[0011] On the edge portion of the strip-shaped member, a first protrusion and a second protrusion are formed side by side, and on the opposite edge portion of the strip-shaped member, a first groove and a second groove are formed side by side. In the pipe manufacturing process, while interposing a restraining weakening wire between adjacent edge portions, the first protrusion is fitted into the first recess and the second protrusion is fitted into the second recess. In the restraint weakening step, the second protrusion is cut by pulling the restraint weakening wire, In the aforementioned pre-weakening step, the second protrusion of the subsequent band portion or the pipe end before joining is cut off. In the aforementioned weakly constrained pipe manufacturing process, it is preferable to fit the first protrusion into the first recessed groove. This allows the same second convex ridge that is weakened in the constraint weakening process to be weakened in the pre-weakening process. The first spiral joint portion is formed by the interlocking of the first groove and the first protrusion. The first protrusion forms the portion of the edge of the first spiral joint portion. The second spiral joint portion is formed by the interlocking of the second groove and the second protrusion. The second protrusion forms the portion of the edge of part 1 that becomes the second spiral joint portion. In the section of the pipe where the restraint is weakened (the section from the second pipe end of the rehabilitated pipe to the junction), the restraint force can be reliably weakened by cutting the second protrusion, and the pipe can be expanded while maintaining its pipe shape by fitting the first protrusion and the first groove together. In the weakly constrained pipe section (the portion of the rehabilitated pipe from the aforementioned junction to the first pipe end), the constraining capacity can be reliably weakened by cutting the second protrusion, and the pipe can be expanded while maintaining its tubular shape by fitting the first protrusion with the first groove. In the weakly constrained pipe section, there is no need to cut the second protrusion with a wire for weakening the constraining, eliminating the risk of the wire breaking or getting caught in the pipe-making machine.

[0012] After the cutting process, it is preferable to allow the first pipe end to expand naturally or to expand by twisting. The first pipe end can undergo natural expansion (natural expansion) due to the elastic restoring force of the wound strip member. If natural expansion is difficult, the first pipe end can be forcibly expanded (forced expansion) by twisting it directly by hand or using a tool. [Effects of the Invention]

[0013] According to the present invention, in the expander pipe manufacturing method, the extended end portion of the rehabilitated pipe can be smoothly and surely expanded without causing buckling or catching of the wire for restraining weakening.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is an explanatory side view showing a rehabilitated pipe under construction by the existing pipe rehabilitation method according to the first embodiment of the present invention in a strong restraint pipe manufacturing process. [Figure 2] FIG. 2 shows the strong restraint pipe manufacturing process. FIG. 2(a) is a cross-sectional view showing the subsequent belt portion of the belt-like member that becomes the rehabilitated pipe at the introduction position into the pipe manufacturing machine. FIG. 2(b) is a cross-sectional view of the pipe end of the rehabilitated pipe and the subsequent belt portion at a position immediately before being joined by the pipe manufacturing machine. FIG. 2(c) is a cross-sectional view of the pipe end of the rehabilitated pipe at the joining position by the pipe manufacturing machine. [Figure 3] FIG. 3(a) is a cross-sectional view of the circular portion IIIa in FIG. 1. FIG. 3(b) is a cross-sectional view of the circular portion IIIb in FIG. 4. [Figure 4] FIG. 4 is an explanatory side view showing the rehabilitated pipe under construction in a pre-weakening process. [Figure 5(a)] FIG. 5(a) is a cross-sectional view of the subsequent belt portion along the line V-V in FIG. 4. [Figure 5(b)] FIG. 5(b) is a cross-sectional view of the subsequent belt portion along the line Vb-Vb in FIG. 5(a). [Figure 6(a)] FIG. 6(a) is an explanatory side view showing the rehabilitated pipe under construction in a weak restraint pipe manufacturing process. [Figure 6(b)] FIG. 6(b) is an explanatory side view showing the rehabilitated pipe under construction in a confluence process. [Figure 7] FIG. 7 shows the weak restraint pipe manufacturing process. FIG. 7(a) is a cross-sectional view of the pipe end of the rehabilitated pipe and the subsequent belt portion at a position immediately before being joined by the pipe manufacturing machine. FIG. 7(b) is a cross-sectional view of the pipe end of the rehabilitated pipe at the joining position by the pipe manufacturing machine. [Figure 8] FIG. 8 is a cross-sectional view along the pipe axis direction of the rehabilitated pipe showing the confluence position in the confluence process and one pitch portions before and after it. [Figure 9(a)] Figure 9(a) is an explanatory side view showing the rehabilitated pipe under construction during the terminal cone formation process. [Figure 9(b)] Figure 9(b) is an explanatory side view showing the rehabilitated pipe under construction during the cutting process. [Figure 10(a)] Figure 10(a) is an explanatory side view showing the rehabilitated pipe under construction during the wire removal process. [Figure 10(b)] Figure 10(b) is an explanatory side view showing the rehabilitated pipe under construction during the terminal expansion process. [Figure 11(a)] Figure 11(a) is an explanatory side view showing a rehabilitated pipe under construction by the existing pipe rehabilitation method according to the second embodiment of the present invention, during the constraint weakening process for merging. [Figure 11(b)] Figure 11(b) is an explanatory side view showing a rehabilitated pipe under construction by the existing pipe rehabilitation method according to the second embodiment, in a junction state. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment (Figures 1-10)> Figure 1 shows the process of rehabilitating an aging existing pipe 1. 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 can also include water supply pipes, agricultural water pipes, gas pipes, hydroelectric power generation water conduits and other buried pipes, as well as tunnels. The aging existing pipe 1 is rehabilitated by lining the inner circumference of the rehabilitated pipe 3.

[0016] As shown in Figure 1, the rehabilitation pipe 3 is a spiral pipe consisting of a strip-shaped member 10. The material of the strip-shaped member 10 is a synthetic resin such as polyvinyl chloride (PVC). As shown in Figure 2(a), the strip-shaped member 10 has a fixed cross-sectional shape and extends in the strip-length direction perpendicular to the plane of the paper in the figure. More specifically, the strip-shaped member 10 integrally comprises a flat strip-shaped strip portion 11, multiple ribs 15 located in the middle of the strip portion 11 in the strip-width direction, and edge portions 13 and 14 on both sides in the strip-width direction that form an uneven cross-section. On one side of the strip-shaped member 10 in the strip-width direction (left-right direction in Figure 2(a)) (the left side in the figure), two (multiple) first convex ribs 13a and second convex ribs 13b are formed parallel to each other on the edge portion 13 (edge ​​portion 1). On the opposite side of the strip-shaped member 10 in the strip-width direction (the right side in Figure 2(a)), two (multiple) first grooves 14a and second grooves 13b are formed parallel to each other on the edge portion 14. The cross-sectional shape of the strip-shaped member 10 can be modified as appropriate.

[0017] Rehabilitated pipe 3 is manufactured using the following expander pipe construction method. <Pipe making process (strongly constrained pipe making process)> As shown in Figure 1, a push-type pipe-making machine 20 is prepared. The pipe-making machine 20 is installed at the bottom of the manhole 4 connected to the pipe opening 1e on the starting side (first side in the direction of the pipe axis, left side in Figure 1) of the existing pipe 1. Strip-shaped members 10 are sequentially fed from the dispensing drum 5 on the ground to the pipe-making machine 20. The pipe-making machine 20 winds the strip-shaped members 10 in a spiral shape, and the adjacent edge portions 13 and 14, offset by one rotation, are joined by interlocking the protrusions and indentations. In this way, a spiral-shaped rehabilitated pipe 3 is produced.

[0018] More specifically, in the pipe-making machine 20, the trailing strip portion 19 of the strip member 10, which follows the pipe end 3e on the starting side (left side in Figure 1) of the rehabilitated pipe 3, is wound in a spiral shape, and as shown in Figure 2(b), the edge portion 14 of the trailing strip portion 19 and the edge portion 13 of the starting side pipe end 3e of the rehabilitated pipe 3 face each other. These edge portions 13 and 14 are gripped by a pair of pinch rollers (not shown) of the pipe-making machine 20, so that, as shown in Figure 2(c), the first convex ridge 13a is fitted into the first concave groove 14a and the second convex ridge 13b is fitted into the second concave groove 14b. This forms a spiral joint portion 12 with two (or more) spirals. As shown in Figure 3(a), the helical joint 12 includes a first helical joint portion 12a formed by the interlocking (joining) of a first groove 14a and a first protrusion 13a, and a second helical joint portion 12b formed by the interlocking (joining) of a second groove 14b and a second protrusion 14b. These two (or more) helical joint portions 12a and 12b create a strongly restrained state in which the edge portions 13 and 14 are almost unable to slide relative to each other in the helical winding direction. Preferably, the joint strength of the first helical joint portion 12a is higher than the joint strength of the second helical joint portion 12b.

[0019] <Wire embedding process> As shown in Figure 1, the restraint-reducing wire 41 is unfurled from the feed reel 42 in parallel with the pipe manufacturing process. As shown in Figure 2(a), the restraint-reducing wire 41 is inserted between the first protrusion 13a and the second protrusion 13b of the subsequent belt portion 19 (Figure 2(a)). As shown in Figures 2(b) to 2(c), the restraint-reducing wire 41 is sandwiched between the edge portions 13 and 14 during the subsequent pipe manufacturing process. As a result, the restraint-reducing wire 41 is embedded inside the helical joint portion 12. Therefore, the edge portions 13 and 14 come into strong contact with each other, resulting in a more securely strong restraint state. As shown in Figure 1, the take-up portion 41b at the tip of the wire 41 is pulled out from the tip 3f of the rehabilitation pipe 3, folded back, passed through the internal space of the rehabilitation pipe 3, and wound onto the winding reel 43. A folded portion 41c of the wire 41 is formed at the tip 3f.

[0020] <Coating process> More preferably, prior to the pipe manufacturing process, as shown in Figure 2(a), a slow-drying hot-melt adhesive 51 is applied from the first nozzle 23 into the first groove 14a of the subsequent band portion 19, and a lubricating sealant 52 is applied from the second nozzle 24 into the second groove 14b. As a result, as shown in Figure 2(c), the hot-melt adhesive 51 is interposed between the inner surface of the first groove 14a and the first protrusion 13a, and the lubricating sealant 52 is interposed between the inner surface of the second groove 14b and the second protrusion 13b. The nozzles 23 and 24 are located inside the pipe-making machine 20, but they may also be located outside the pipe-making machine 20, at a distance from it.

[0021] <Pressing process> As shown in Figure 1, the rehabilitated pipes 3 manufactured in this manner are sequentially pushed out from the pipe-making machine 20 and inserted into the existing pipe 1. The tip 3f of the rehabilitated pipe 3 (the second pipe end in the direction of the pipe axis) may be pulled by a winch or the like. The outer diameter (manufacturing diameter) of the rehabilitated pipe 3 during manufacturing is made smaller than the inner diameter of the existing pipe 1. This reduces friction between the rehabilitated pipe 3 and the existing pipe 1 as it is being pushed into the existing pipe 1.

[0022] As shown by the dashed line in Figure 1, the pipe manufacturing process is carried out until the tip 3f of the rehabilitated pipe 3 reaches the pipe opening 1f on the receiving side (second side) of the existing pipe 1. This ensures that the rehabilitated pipe 3 covers the entire length of the existing pipe 1. Preferably, the tip 3f of the rehabilitated pipe 3 is prevented from rotating relative to the pipe opening 1f by a jig (not shown) or the like. At this stage, the rehabilitated pipe 3 is a small-diameter pipe section 30 that is smaller in diameter than the existing pipe 1 and is not expanded throughout its entire length. Furthermore, throughout the entire length of the small-diameter pipe section 30, the edge portions 13 and 14 that constitute the helical joint 12 are constrained to not slide relative to each other in the winding direction, forming a tightly constrained pipe section 30a.

[0023] <Restraint weakening process> After pipe manufacturing, as shown in Figure 4, the winding reel 43 pulls the take-up portion 41b towards the starting end (first side, left side in Figure 4) in the direction of the pipe axis. As a result, the portion 41a embedded in the helical joint portion 12 of the wire 41 is sequentially pulled out from the receiving end (second side) of the rehabilitated pipe 3, and the folded portion 41c moves along the spiral winding direction from the receiving end (second side) to the starting end (first side) (from right to left side in Figure 3). At this time, as shown in Figure 3(b), the base portion of the second convex ridge 13b is cut by the folded portion 41c of the wire 41, thereby releasing the joint of the second helical joint portion 12b. The joint between the first helical joint portions 12a is maintained. As a result, as shown in Figure 4, the restraining force between the edge portions 13 and 14 is gradually weakened from the receiving end (second side) to the starting end (first side) of the rehabilitation pipe 3, thereby forming a restrained-weakening pipe portion 31. In the restrained-weakening pipe portion 31, the edge portions 13 and 14 are in a weakly restrained state that allows them to slide relative to each other in the winding direction.

[0024] <Expansion Process> Parallel to the winding of the wire 41, the pipe-making machine 20 (expansion pipe-making machine) feeds the trailing strip portion 19 of the strip member 10 that follows the rehabilitated pipe 3 into the rehabilitated pipe 3 and incorporates it into the rehabilitated pipe 3. As a result, the small-diameter pipe section 30 in the rehabilitated pipe 3, which remains in a tightly constrained state, is twisted, and the entire small-diameter pipe section 30 is rotated integrally and pushed toward the destination end (second side, right side in Figure 4). In the constrained-weakening pipe section 31 on the destination end side of the small-diameter pipe section 30 in the rehabilitated pipe 3, the edge portions 13 and 14 slide against each other along the winding direction, and the circumference is expanded (increased in diameter). Therefore, the constrained-weakening pipe section 31 includes a cone portion 32 that is undergoing expansion deformation and an expanded large-diameter pipe section 33. The cone portion 32 is frustoconical in shape, expanding in diameter from the unexpanded small-diameter pipe section 30 toward the large-diameter pipe section 33. The small-diameter end 32e of the cone section 32 is continuous with the small-diameter pipe section 30, having the same diameter. The large-diameter end 32f of the cone section 32 is continuous with the large-diameter pipe section 33, having the same diameter. The large-diameter pipe section 33 is larger in diameter than the small-diameter pipe section 30 and adheres to the entire circumference of the inner surface of the existing pipe 1.

[0025] As shown in Figure 4, through the restraint weakening process and the expansion process, the restraint weakened pipe portion 31 and thus the large-diameter pipe portion 33 gradually extend from the reaching end 3f of the rehabilitated pipe 3 to the starting end side (first side, left side in Figure 4), and the cone portion 32 gradually moves toward the starting end side.

[0026] <End of extended pipe processing process> After the cone portion 32 reaches a predetermined position 1d near the pipe opening 1e in the existing pipe 1 and thus the pipe-making machine 20, the expanded end portion 39 (Figures 4 and 10(b)) of the rehabilitated pipe 3 on the pipe opening 1e side (first side) from the predetermined position 1d is expanded as follows. Preferably, the predetermined position 1d is set to be sufficiently close to the pipe-making machine 20, but if it is any closer to the pipe-making machine 20, the length of the cone portion 32 cannot be sufficiently secured, and buckling or the like may occur. The expanded end pipe processing process includes a pre-weakening process, a weak-restraint pipe manufacturing process, a merging process, a terminal cone formation process, a cutting process, and a terminal expansion process.

[0027] <Pre-weakening process> First, as shown in Figure 4, when, for example, the large-diameter end 32f of the cone portion 32 reaches a predetermined position 1d, the drive of the pipe-making machine 20 and the winding of the winding reel 43 are temporarily stopped. This interrupts the restraint weakening process and the expansion process. Then, as shown in Figures 5(a) and 5(b), the second protrusion 13b of the subsequent belt portion 19 is continuously cut from the starting end 13d toward the feed drum 5 side (upstream side in the feeding direction). As a result, the portion of the edge portion 13 of the subsequent belt portion 19 that will become the second helical joint portion 12b becomes unable to be joined to the edge portion 14. Cut marks 13c of the second protrusion 13b are formed in a streaky pattern on the edge portion 13. The first protrusion 13a of the subsequent belt portion 19, i.e., the portion that will become the first helical joint portion 12a, is left uncut and maintains its ability to be joined to the edge portion 14. This weakens the restraining force between adjacent edge portions 13 and 14 before they are joined together.

[0028] The second protrusion 13b is cut by hand. For example, after making an incision at the starting end 13d with a handsaw, the second protrusion 13b is grabbed with pliers or anguilla and torn off. The position of the cutting start end 13d is set so that, by the next weak-restraint pipe-making process (Figure 7), the cutting start end 13d is sent to the small-diameter pipe section 30 after being manufactured by the pipe-making machine 20. Preferably, the cutting start end 13d is set by the weak-restraint pipe-making process (Figure 7) so that it reaches the desired junction position 35 (Figure 6(b)). The cutting length L of the second protrusion 13b (distance from the cutting start end 13d to the cutting end 13e) is set so that the cutting end 13e has not yet reached the cutting position 38c of the rehabilitated pipe 3 at the time of the subsequent separation process (Figure 9(b)).

[0029] If the length of the trailing strip portion 19 from the cutting start end 13d to the feed drum 5 (Figure 4) is less than the length L to be cut, the second protrusion 13b may be cut as far as it can be cut, and the pre-weakening process may be restarted midway through the next weak-restraint pipe manufacturing process (Figure 7) to cut the remaining portion. In short, the pre-weakening process only needs to be performed from the time the cone portion 32 reaches a predetermined position 1d, and it is not necessary to complete the pre-weakening process before the next process.

[0030] A cutting tool such as a cutter may be fixed to the manhole 4 or the pipe-making machine 20 with a cut into the second protrusion 13b at the starting end 13d (start of the pre-weakening process), and as the subsequent strip 19 is fed in the feeding direction by the drive of the pipe-making machine 20 in the next weak-restraint pipe-making process, the second protrusion 13b may be continuously cut by the fixed cutting tool. The location where the fixed cutting tool is installed is not limited to the track of the trailing belt section 19 outside the pipe-making machine 20, but may also be on the track of the trailing belt section 19 introduced inside the pipe-making machine 20, or on the unfitted second protrusion 13b (Figure 2(b)) at the starting pipe end 3e.

[0031] As shown in Figure 5(b), preferably, a marking 16 is applied to the starting end 13d of the cut. The marking 16 is provided on at least the front surface 10a of the strip-shaped member 10 (the surface that will be the inner circumferential surface of the rehabilitation pipe 3). A similar marking may also be provided on the back surface of the strip-shaped member 10 (the surface that will be the outer circumferential surface of the rehabilitation pipe 3). Examples of marking means include adhesive tape and oil-based pens.

[0032] <Weakly constrained pipe manufacturing process> Subsequently, as shown in Figure 6(a), the drive of the pipe-making machine 20 is restarted. As a result, as shown in Figures 7(a) to 7(b), the subsequent band portion 19, whose restraining force has been weakened in advance, is introduced into the pipe-making machine 20 and pipe-made. At this time, the first protrusion 13a and the first recess 14a are fitted together, while the second protrusion 13b and the second recess 14b are not fitted together (Figure 2(c)). Therefore, of the first and second helical joint portions 12a and 12b of the helical joint portion 12, only the first helical joint portion 12a is formed. Consequently, the pipe portion manufactured by the weak-restraint pipe-making process becomes a weak-restraint pipe portion 34, in which the restraining force of the helical joint portion 12 is weak from the beginning of the joining process. As shown in Figure 6(a), the weak-restraint pipe portion 34 is fed from the pipe-making machine 20 to the small-diameter pipe portion 30. In the weakly constrained pipe manufacturing process, the application of hot melt adhesive 51 to the first groove 14b may be omitted.

[0033] Furthermore, in parallel with the start of the weakened-restraint pipe manufacturing process, the restraint weakening process is restarted by taking in the restraint weakening wire 41 with the winding reel 43. As a result, the second protrusion 13b of the end 30d on the cone side (right side in Figure 6(a)) of the small-diameter pipe section 30 is cut by the folded portion 41c of the restraint weakening wire 41 (see Figure 3(b)). Therefore, the connection of the second helical joint portion 12b at the cone side end 30d is released, weakening the restraint force of the helical joint portion 12, and allowing the edge portions 13 and 14 to slide relative to each other in the winding direction.

[0034] As shown in Figure 6(a), at this stage, the small-diameter pipe section 30 has a weakly constrained pipe section 34 from the starting pipe end 3e to the cutting start end 13d, and a strongly constrained pipe section 30a from the cutting start end 13d to the cone-side end 30d. The weakly constrained pipe section 34 is restricted from expanding in diameter by being sandwiched from both sides in the pipe axis direction by the pipe-making machine 20 and the strongly constrained pipe section 30a. As a result, when the pipe-making machine 20 is driven, the weakly constrained pipe section 34 and the strongly constrained pipe section 30a of the small-diameter pipe section 30 rotate together, and the edge portions 13 and 14 of the cone section 32 slide against each other in the circumferential expansion direction. This causes expansion to progress, and the cone section 32 moves toward the pipe-making machine 20 side (first side, left side in Figure 6(a)).

[0035] <Merge process> By performing the weak-restraint pipe manufacturing process by driving the pipe manufacturing machine 20 and the restraint weakening process by driving the winding reel 43 in parallel, the weak-restraint pipe portion 34 of the small-diameter pipe section 30 is extended toward the cone section side (second side, right side in Figure 6(a)), and the cone section 32 and consequently the restraint weakened pipe portion 31 is extended toward the pipe manufacturing machine side (first side, left side in Figure 6(a)). As a result, the weak-restraint pipe portion 34 and the restraint weakened pipe portion 31 are brought closer together, and the length of the strongly-restraint pipe portion 30a is shortened. A cutting start end 13d is located at the cone section side end of the weak-restraint pipe portion 34. A folded-back portion 41c is located at the pipe manufacturing machine side end of the restraint weakened pipe portion 31. Therefore, the weak-restraint pipe manufacturing process and the restraint weakening process bring the cutting start end 13d and the folded-back portion 41c closer together.

[0036] By continuing the weak-restraint pipe manufacturing process and the restraint weakening process, eventually, as shown in Figure 6(b), the end of the weak-restraint pipe portion 34 on the cone side and the end of the restraint-weakening pipe portion 31 on the pipe manufacturing machine side will overlap in the pipe axis direction of the rehabilitated pipe 3, and the weak-restraint pipe portion 34 and the restraint-weakening pipe portion 31 will merge. More specifically, as shown in Figure 8, the cutting start end 13d, that is, the start end 13d of the portion of the second helical joint portion 12b that has become unjoinable, and the folded-back portion 41c, that is, the end end 13f of the portion of the second helical joint portion 12b that has been released, are positioned at the same location in the helical extension direction (winding direction) of the helical joint portion 12 and merge with each other.

[0037] Preferably, a camera vehicle 6 is placed inside the rehabilitated pipe 3 to photograph the inner circumferential surface of the rehabilitated pipe 3, and while confirming the positions of the marking 16 and the folded portion 41c, the pipe-making machine 20 and the winding reel 43 are driven and adjusted so that the marking 16 and the folded portion 41c are positioned at the same location in the winding direction. The marking 16 indicates the position of the cutting start end 13d. Furthermore, the end of the weakly restrained pipe portion 34 on the cone side may be slightly offset towards the cone side (to the right in Figure 6(b)) compared to the end of the weakened restrained pipe portion 31 on the pipe-making machine side. The cutting start end 13d may slightly extend into the cone portion 32.

[0038] As shown in Figure 6(b), the confluence eliminates the strongly constrained pipe section 30a, and the entire area of ​​the small-diameter pipe section 30 becomes the weakly constrained pipe section 34. The weakly constrained pipe section 34 is directly connected to the cone section 32 of the weakened constrained pipe section 31. As a result, the edge sections 13 and 14 that constitute the helical joint 12 in the small-diameter pipe section 30 and cone section 32 on the outside of the pipe-making machine 20 become able to slide relative to each other in the winding direction. The small-diameter pipe section 30 inside the pipe-making machine 20 is restricted from sliding relative to each other by the pipe-making machine 20.

[0039] <End coning process> Once the aforementioned junction is confirmed, the winding reel 43 stops taking in the restraint-reducing wire 41, and the restraint-reducing process is terminated. Furthermore, the winding reel 43 is allowed to rotate freely. Next, as shown in Figure 9(a), the pipe-making machine 20 is driven to feed the trailing strip 19 to the pipe end 3e of the rehabilitated pipe 3. This causes the edges 13 and 14 of the spiral joint 12 in the small-diameter pipe section 30 and cone section 32 on the outside of the pipe-making machine 20 to slide relative to each other toward the expanding side in the winding direction, forming a terminal cone section 38 that expands in diameter toward the large-diameter pipe section 33 from the outlet of the pipe-making machine 20.

[0040] Since the taper angle of the terminal cone section 38 is gentler than the taper angle of the cone section 32 up to the previous step (Figure 6(b)), there is no risk of buckling. Also, since it is not necessary to cut the second convex 13b with the restraining weakening wire 41, there is no risk of the restraining weakening wire 41 breaking or getting caught in the pipe-making machine 20. Once it is confirmed that the smaller diameter side (the pipe-making machine 20 side) of the terminal cone section 38 has been slightly enlarged, the drive of the pipe-making machine 20 is stopped.

[0041] <Separation process> Next, as shown in Figure 9(b), the portion of the rehabilitation pipe 3 between the pipe-making machine 30 and the pipe opening 1e is cut. This separates the pipe-making machine 20 from the rehabilitation pipe 3. At this time, the embedded portion 41a of the restraint weakening wire 41 is cut at the same cutting position 38c as the rehabilitation pipe 3. After cutting, the pipe-making machine 20 is removed.

[0042] <Wire removal process> Next, as shown in Figure 10(a), the embedded portion 41a of the restraint-reducing wire 41 is removed from inside the terminal cone portion 38. Simply removing it is sufficient; it is not necessary to cut the second protrusion 13b with the restraint-reducing wire 41. Furthermore, if the cutting position 38c in the aforementioned separation process (Figure 9(b)) is on the opposite side from the pipe-making machine 20 side (right side in Figure 9(b)) from the folded portion 41c, the wire removal process is unnecessary.

[0043] <Terminal extension process> As shown in Figure 10(a), separation from the pipe-making machine 20 releases the pipe end 38e of the terminal cone section 38, causing the terminal cone section 38 to expand naturally. The pipe end 38e may also be expanded by twisting it manually or with a tool. In this way, as shown in Figures 10(a) to 10(b), the terminal cone portion 38 can be expanded until it becomes a straight expanded terminal portion 39, and the expanded terminal portion 39 can be brought into close contact with the inner circumference of the existing pipe 1. Even if the manhole 4 is narrow, or even if the pipe-making machine 20 has to be installed close to the pipe opening 1e, the expansion process of the expanded terminal portion 39 can be carried out smoothly and reliably without causing buckling, wire cutting, snagging, etc. <Adhesive curing process> Subsequently, the slow-drying hot-melt adhesive 51 is cured.

[0044] Next, other embodiments of the present invention will be described. In the following embodiments, components that overlap with those described above are denoted by the same reference numerals in the drawings and their descriptions are omitted. <Second Embodiment (Figure 11)> As shown in Figure 11, the second embodiment relates to another aspect of the merging process. As shown in Figure 11(a), in the weakly constrained pipe-making process, when the cutting start end 13d is fed out of the pipe-making machine 20 and reaches a predetermined location in the small-diameter pipe section 30, the pipe-making machine 20 is stopped.

[0045] Next, with the pipe-making machine 20 still stopped, the winding reel 43 is rotated to take in the restraint-reducing wire 41. As a result, the folded portion 41c of the restraint-reducing wire 41 moves spirally toward the pipe-making machine 20 along the spiral joint 12, and the second protrusion 13b of the small-diameter pipe section 30 is cut by the folded portion 41c (see Figure 3(b)). Therefore, the restraint-reducing pipe section 31 is extended toward the pipe-making machine 20, and the edges 13 and 14 of the extended portion become slidable relative to each other in the winding direction, causing the small-diameter end 32e of the cone section 32 to move toward the pipe-making machine 20. The large-diameter end 32f of the cone section 32 remains in its original position. Consequently, the length of the cone section 32 increases and the taper angle becomes gentler.

[0046] As shown in Figure 11(b), the restraint weakening wire 41 is pulled in until the folded portion 41c is positioned at the same location as the marking 16 along the spiral extension direction (winding direction) of the spiral joint portion 12. This brings the weak restraint pipe portion 34 and the restraint weakening pipe portion 31 together.

[0047] The present invention is not limited to the embodiments described above, and various modifications can be made without departing from its spirit. For example, in the pre-weakening process, instead of cutting the second protrusion 13b, the first protrusion 13a may be cut. The cross-sectional shape of either protrusion 13a or 13b may be reduced by machining, or a part of either groove 14a or 14b may be machined to reduce the fitting force. [Industrial applicability]

[0048] The present invention can be applied, for example, to the rehabilitation work of aging sewer pipes. [Explanation of Symbols]

[0049] 1 Existing pipe 1d in place 1e Launching side pipe opening (first side pipe opening) 1f Receiving pipe port (second pipe port) 3 Rehabilitation pipe 3e Starting pipe end (first pipe end) 3f Receiving end of pipe (second pipe end) 10 Strip-shaped member 10a Front side 11 Band part 12 Spiral joint 12a 1st spiral joint part 12b 2nd spiral joint 13 Edge of 1 13a 1st protrusion 13b Second protrusion 13c Cutting marks 13d Cutting start point (the starting point of the unjoinable portion of the second helical joint) 13e Cutting end of the second convex ridge (end of the unjoined portion of the second helical joint) 13f Cutting end of the second convex ridge (end of the unjointed portion of the second helical joint) 14. The opposite edge 14a First groove 14b Second groove 16 Markings 19. Following section 20 Pipe making machine 30 Small diameter pipe section 30a Strongly restrained tube part 30d End of cone section in small diameter pipe section 31 Restraint weakened pipe section 32 Cone section 32e Small diameter end of the cone section 32f Large diameter end of the cone section 33 Large diameter pipe section 34 Weakly restrained tube section 35 Merging position 38 End cone section 39 Extended Termination Section 39e Tube end after separation 41 Wire for weakening restraint 41a Embedded portion 41b Pickup section 41c Folded section 42 Reel 43. Reel 51 Hot melt adhesive

Claims

1. In a method for rehabilitating an existing pipe, a spiral-shaped rehabilitation pipe is formed by winding a strip-shaped member in a spiral shape and joining adjacent edges that are offset by one full turn. This rehabilitation pipe is manufactured to a diameter smaller than the inner diameter of the existing pipe and installed inside the existing pipe. Subsequently, a restraint weakening step is performed to form a restraint-weakening pipe portion by sequentially weakening the restraint force between the adjacent edges along the winding direction from the second side to the first side in the pipe axis direction of the rehabilitation pipe. At the same time, a subsequent strip portion of the strip-shaped member that follows the first end of the rehabilitation pipe is fed into the rehabilitation pipe by a pipe manufacturing machine, thereby expanding the circumference of the restraint-weakening pipe portion. A process performed from the time the cone section, which expands in diameter from the unexpanded small-diameter section to the expanded large-diameter section of the rehabilitated pipe, reaches near the pipe-making machine, comprising a pre-weakening step that weakens the restraining force between adjacent edge sections before joining, A weak-restraint pipe-making process in which the adjacent edge portions that have undergone the aforementioned pre-weakening process are joined together by the pipe-making machine and fed into the small-diameter pipe section, A merging process is performed to merge the weakly restrained pipe portion manufactured by the weakly restrained pipe manufacturing process in the small-diameter pipe section with the restrained weakened pipe portion. Subsequently, a cutting step is performed to separate the pipe-making machine from the rehabilitated pipe, A method for rehabilitating existing pipes, characterized by comprising the following:

2. In the pipe manufacturing process, multiple spiral joints, including a first spiral joint and a second spiral joint, are formed by joining the adjacent edge portions together. In the aforementioned restraint weakening step, the joined state of the first helical joint portion of the helical joint is maintained, while the joint of the second helical joint portion is released. In the aforementioned pre-weakening step, the subsequent band portion or the portion of the pipe end before joining that will become the second helical joint portion is made unjoinable. In the aforementioned weakly constrained pipe manufacturing process, only the first helical joint portion of the first and second helical joint portions is formed. The method for rehabilitating an existing pipe according to claim 1, characterized in that, in the merging step, the starting end of the portion that could not be joined is merged with the ending end of the portion that was released from the joint.

3. A first protrusion and a second protrusion are formed side by side on one edge portion in the width direction of the strip-shaped member, and a first groove and a second groove are formed side by side on the opposite edge portion in the width direction of the strip-shaped member. In the pipe manufacturing process, while interposing a restraining weakening wire between adjacent edge portions, which consist of one edge portion and the opposite edge portion, the first protrusion is fitted into the first groove and the second protrusion is fitted into the second groove. In the restraint weakening step, the second protrusion is cut by pulling the restraint weakening wire, In the aforementioned pre-weakening step, the second protrusion of the subsequent band portion or the pipe end before joining is cut off. The method for rehabilitating an existing pipe according to claim 1, characterized in that the first protrusion is fitted into the first recess in the weakly constrained pipe manufacturing process.

4. A method for rehabilitating an existing pipe according to any one of claims 1 to 3, characterized in that, after the cutting step, the pipe end is allowed to expand naturally or is twisted to expand its diameter.

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