JPH04314525A - Resin pipe introducing method and resin pipe introducing device - Google Patents

Abstract

PURPOSE:A long resin pipe is molded reasonably and inserted easily into an existing pipe for traction. CONSTITUTION:A flat resin pipe 15 which is molded into the same diameter as the inside diameter of an existing pipe 3 or a little smaller outer diameter and processed so that a sectional area becomes small is bent gently along a pipe axis by a pair of uneven molding rollers 6 having the high radius of curvature in the vicinity of a pulling-out port of a heating and pressurizing vessel 4 and premolded. The flat resin pipe 15 is pulled down in the vicinity of the existing pipe, molding-processed gradually by a pair of molding rollers 7, 8 whose radii of curvature become smaller in order and bending of the flat resin pipe is made large. The flat resin pipe bent and molded large is bent by a recessed type roller 9 so that both ends of a widthwise direction are approached and introduced into the existing pipe by molding into a double wall cylindrical state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin pipe introduction method and a resin pipe introduction apparatus for lining synthetic resin pipes into existing pipes such as sewerage, water supply, oil pipes, and all other types of pipes.

0002

BACKGROUND OF THE INVENTION A method of forming synthetic resin pipes on the inner surface of existing pipes has been adopted for the purpose of reinforcing the strength of existing pipes such as sewer pipes and water pipes, preventing corrosion, preventing water leakage and flooding, and improving flow rates.

[0003] Two methods have been adopted for this construction: the inverted lining method, in which the lining material is inverted and crimped onto the inner surface of the existing pipe, and the lining method, in which the lining material is pulled into the existing pipe, expanded, and crimped onto the inner surface of the existing pipe. .

The lining method is a method in which a resin pipe made of a thermoplastic resin such as vinyl chloride, polypropylene, polyethylene, or polybutene is inserted into an existing pipe, and the inserted resin pipe is brought into close contact with the inner wall of the existing pipe. In this lining construction method, when using a resin pipe with an outer diameter that is approximately the same or slightly larger than the existing pipe, the resin pipe is flattened to reduce its cross-sectional area in order to be inserted into the existing pipe.

[0005] In order to reduce the cross-sectional area of a resin pipe, for example, Japanese Patent Laid-Open No. 64-56531 and Japanese Patent Laid-Open No. 2-4
As shown in Japanese Patent Publication No. 3024 or Japanese Unexamined Patent Publication No. 2-154882, the first step is to flatten an extruded resin pipe in the diametrical direction.
In the second step, the cross section is processed into a U-shape or a V-shape by curving it in the longitudinal direction so that both ends in the major diameter direction are close to each other. Then, a resin pipe having a U-shaped cross section or the like is wound up on a drum or the like and stored. When lining an existing pipe with this resin pipe, transport the resin pipe wound on a drum or the like to the position of the existing pipe, insert the U-shaped resin pipe into the existing pipe, and line both ends or one end of the resin pipe. The tube has a sealed structure, and heated pressurized fluid is supplied inside the tube, or a tube expansion tool such as a pig is moved while supplying heated fluid to soften and expand the tube, and the tube is brought into close contact with the inner surface of the existing tube.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 2-196627, when a flattened resin pipe is wound onto a drum and lined in an existing pipe, the resin pipe is heated from the inside and outside. The resin pipe is pulled into the mouth of an existing pipe while being softened, and then sharply bent into a U-shape using a pair of rollers before being inserted into the existing pipe. The resin pipe inserted into the existing pipe is heated only internally, without external heating, and the outer layer of the resin pipe is cooled and hardened before being pulled.

[0007]

[Problem to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 2-154
In order to reduce the cross-sectional area of an extruded resin pipe, the lining method shown in Publication No. 882, etc. processes the extruded resin pipe into a U-shape in a two-step processing process, and then molds the resin pipe into a drum, etc. Since it is rolled up, it has a large cross-sectional shape when rolled up, making it difficult to store and transport.

[0008] Furthermore, the larger the diameter of the resin pipe, the larger the cross-sectional shape when it is rolled up, and it is not possible to wind up a long resin pipe with a diameter of 500 mm or more, making it difficult to line a long distance of existing pipe. The disadvantage was that it was not possible.

[0009] Such disadvantages are explained in Japanese Patent Application Laid-Open No. 2-19662.
As shown in Japanese Patent No. 7, this problem can be solved by winding the resin pipe in a flattened state onto a drum. However, when pulling a resin pipe with an outer diameter of 70% or more of the inner diameter of the existing pipe into the existing pipe, it is impossible to pull it into the existing pipe while it is in a flat state.
In the construction method disclosed in Japanese Patent No. 196627, a flat resin pipe that has been heated and softened from the inside and outside is pulled out to the vicinity of the existing pipe opening, processed into a U-shape, and then inserted into the existing pipe. When this flat resin pipe is processed into a U-shape, it is sharply bent by a pair of rollers, so the stress applied to the flat resin pipe becomes large and the inside of the U-shape becomes wavy. Since the outer surface of this resin pipe is cooled and hardened and then pulled into the existing pipe, the resin pipe is installed inside the existing pipe with undulations on the inside of the U-shape, and when it expands under pressure, local distortion occurs. It has the disadvantage that it leaves a residue and can crack or tear. Furthermore, when the resin pipe is pulled inside the existing pipe, it is heated only from the inner surface, so there is a risk that distortion will occur due to internal stress, which may cause stress cracking.

[0010] Furthermore, when pulling a resin pipe inside an existing pipe, heating from the outside of the resin pipe, which had been heated from the inside and outside, is stopped and heating is performed only from the inside. Residual heat from the molding process remains in the resin pipe, and the residual heat restores the shape of the resin pipe, increasing its outer diameter and coming into contact with the inner surface of the existing pipe. This also had the disadvantage of increasing friction between the resin pipe and the existing pipe, making long-distance construction difficult.

[0011] The present invention has been made to solve these shortcomings, and provides a resin pipe introducing method and an introducing device that can easily mold a long resin pipe and easily insert it into an existing pipe and tow it. The purpose is to obtain.

0012

[Means for Solving the Problems] A method for introducing a resin pipe according to the present invention is to use a thermoplastic resin pipe which has been shaped to have an outer diameter that is the same as or slightly smaller than the inner diameter of an existing pipe so that its cross-sectional area is small. In a resin pipe introduction method in which the flat resin pipe is flattened and guided and introduced into an existing pipe, the flat resin pipe pulled out from the heated and pressurized container is installed near the outlet of the heated and pressurized container, and has a large radius of curvature. The flat resin pipe is bent gently along the pipe axis using a pair of forming rollers with convex and concave surfaces, and then pulled down while maintaining a heated and pressurized state near the existing pipe. After gradually enlarging the radius using multiple pairs of forming rollers that gradually become smaller, both ends of the flat resin pipe in the width direction are formed using concave rollers whose rotational axes are orthogonal to the rotational axes of the plurality of pairs of forming rollers. It is characterized by being formed into a curved shape so that the pipes are close to each other and being introduced into the existing pipe.

[0013] When inserting a curved resin pipe into an existing pipe, a bellows pipe having an inner diameter larger than the outer diameter of the curved resin pipe is installed for a certain length from the existing pipe opening. It is preferable to introduce the resin pipe into the existing pipe while suppressing its outer diameter with a bellows pipe.

[0014] Furthermore, the resin pipe introducing device according to the present invention flattens a thermoplastic resin pipe which has been shaped to have the same diameter or a slightly smaller outer diameter as the inner diameter of the existing pipe to memorize its shape so that its cross-sectional area becomes smaller. In the resin pipe introduction device that guides the flat resin pipe and introduces it into the existing pipe, it is installed between a heated and pressurized container containing the flat resin pipe and the existing pipe opening, and guides the flat resin pipe while supplying heated fluid. An introduction guide hose, a pair of uneven forming rollers with a large radius of curvature that are installed near the outlet of the heated and pressurized container in the introduction guide hose, and A plurality of pairs of forming rollers are provided, each having a rotation axis parallel to the rotation axis of the forming roller, and each having a radius of curvature that is successively smaller; It is characterized by comprising a concave roller having a rotation axis perpendicular to the rotation axis of the forming roller.

[0015]

[Operation] In this invention, a thermoplastic resin pipe is formed to have an outer diameter that is the same as or slightly smaller than the existing pipe inner diameter, has a shape memory, is flattened to have a smaller cross-sectional area, and then heated by winding or folding it around a drum. A flat resin pipe housed in a pressurized container is drawn out through an introduction guide hose in which heated pressurized fluid is circulated and introduced into the existing pipe. When this flat resin pipe passes through the introduction guide hose, it is preformed by gently bending it along the pipe axis using a pair of concave and convex forming rollers with a large radius of curvature near the outlet of the heated and pressurized container. To move a flat resin pipe to the vicinity of an existing pipe without bending. By gradually forming the flat resin pipe that has been pulled down to the vicinity of the existing pipe using multiple pairs of forming rollers whose radius of curvature is gradually decreasing, the bending of the flat resin pipe can be increased without applying excessive stress. do. This largely bent flat resin pipe is bent into a double-walled cylindrical shape using concave rollers whose rotational axes are orthogonal to the rotational axes of multiple pairs of forming rollers so that both ends in the width direction are close together. and introduce it into the existing pipe.

When inserting this double-walled cylindrical resin pipe into an existing pipe, a bellows pipe having an inner diameter larger than the outer diameter of the molded resin pipe is installed for a certain length from the existing pipe opening. By introducing the molded resin pipe into the existing pipe while suppressing its outer diameter with the inner wall of the bellows pipe, the molded resin pipe is prevented from recovering its shape and increasing its outer diameter due to residual heat during molding.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the present invention. As shown in the figure, a resin pipe introduction device 1 includes an existing pipe 3 buried underground 2 and a heated and pressurized container 4 installed above ground.
For example, a split introduction guide hose 5 connecting the
An upper guide roller 6 provided near the outlet of the heated and pressurized container 4 in the introduction guide hose 5, a lower guide roller 7 and a squeeze forming roller provided close to each other near the pipe opening of the existing pipe 3. - roller 8 and concave vertical roller 9.

At the connection part of the introduction guide hose 5 to the existing pipe 3, there is a shielding plate 1 having a valve on the outer periphery to shut off heated pressurized fluid.
0 is attached. The lower end of this introduction guide hose 5 and a heated fluid generating device 11 consisting of a hot water boiler, a steam boiler, etc. installed on the ground are connected to a heated fluid outgoing hose 12.
The heating fluid generating device 11 and the heating and pressurizing container 4 are connected by a heating fluid return hose 13.

As shown in FIG. 2, the upper guide roller 6 has a rotating shaft mounted in a horizontal direction, and has an upper roll 61 having a convex center portion with a large radius of curvature, and a concave lower roll 61. 62
The upper roll 61 has relief portions 63 at both ends. The rotating shafts of the lower guide roller 7 and the squeeze forming roller 8 are mounted parallel to the rotating shaft of the upper guide roller 6. The lower guide roller 7, as shown in FIG. The roll 71 has relief portions 73 at both ends. The squeeze forming roller 8 is constructed as shown in FIG. 4 and consists of an upper roll 81 whose central part is convex with a radius of curvature smaller than that of the lower guide roller 7, and a concave lower roll 82. , the upper roll 81 has relief portions 83 at both ends. The concave vertical roller 9 provided after the squeeze forming roller 8 is installed with its rotating shaft perpendicular to the rotating axis of the squeeze forming roller 8, and has a large radius of curvature as shown in FIG. A pair of concave rolls 91
,92.

Concave vertical rollers 9 are installed at the pipe opening of the existing pipe 3.
A bellows tube 13 having a predetermined inner diameter and a constant length according to the gap h is attached.

Next, using the resin pipe introducing device 1 configured as described above, a flat resin pipe 15 is inserted into the existing pipe 3.
Explain the operation when introducing. First, as shown in FIG. 6, a resin pipe 15a made of thermoplastic resin such as vinyl chloride, polypropylene, polyethylene, polybutene, etc., and having a shape memorized outer diameter that is approximately the same as or slightly smaller than the inner diameter of the existing pipe 3 is formed by extrusion molding. do. This resin pipe 15a is softened in a heated atmosphere and crushed so that voids 16 remain inside both ends and the center portions are brought into close contact with each other, resulting in a flat resin pipe 15 with a reduced cross-sectional area as shown in FIG.
It is formed into a shape and wound onto a drum.

When lining the inner surface of the existing pipe 3 with this flat resin pipe 15, the flat resin pipe 15 wound around a drum is stored in a heating and insulating container 4 and transported to the site together with the heated fluid generating device 11. For example, if the existing pipe 3 is a sewer pipe, it is installed on the ground near the manhole 19. Further, after passing the traction belt 17 from the far end of the existing pipe 3 to the manhole 16, the bellows pipe 14 is inserted from the end of the existing pipe 3 and attached to the mouth of the existing pipe 3.

Next, the tip of the flat resin pipe 15 is pulled out from the outlet of the heating and heat-insulating container 4, and then the introduction guide hose 5 is connected between the heating and heat-insulating container 4 and the existing pipe 3. At this time, the tip of the flat resin pipe 15 and the end of the traction belt 17 are tied together. Further, a heated fluid outgoing hose 12 is connected between the heated fluid generating device 11 and the introduction guide hose 5, and a heated fluid returning hose 13 is connected between the heated and pressurized container 4 and the heated fluid generating device 11. Connect with. In this way, the circulation system of the heating fluid generated in the heating fluid generating device 11 is configured to include the heating fluid generating device 11, the heating fluid outgoing path hose 12, the introduction guide hose 5, the heating and pressurizing container 4, and the heating fluid returning path hose. S13,
A heated fluid generator 11 is formed.

In this state, a pressurized fluid heated from the heated fluid generator 11 to a softening temperature above the shape recovery temperature of the flat resin pipe 15 and below the shape memory temperature is supplied to the circulation system, and is wound around a drum or the like. A certain flat resin pipe 15 is brought into a softened state. Then, the traction belt 17 is pulled from the far end of the existing pipe 3, and the softened flat resin pipe 15 is pulled out from the heated and pressurized container 4 so that no tension is applied to the introduction guide hose 5. At this time, since fluid pressure is applied to the softened flat resin pipe 15 by the heated pressurized fluid, it is smoothly sent to the upper guide roller 6 while remaining flat without expanding and recovering its shape.

As shown in FIG. 2, the flat resin pipe 15 sent to the upper guide roller 6 is held uniformly in the center by an upper roll 61 and a lower roll 62 having a large radius of curvature, and is rolled gently. It is bent and formed and moves downward. When this flat resin pipe 15 is bent and formed by the upper guide roller 6, both ends of the flat resin pipe 15 are bent by the upper guide roller 6.
Since the gap 16 is located in the relief part 63 of the groove 61, the gap 16 remains as it is. This gently bent flat resin pipe 15 is sent to the lower guide roller 7 through the introduction guide hose 5. When this flat resin pipe 15 is fed to the lower guide roller 7, since the flat resin pipe 15 is gently bent, it can be fed to the lower guide roller 7 without bending.
You can move up to La 7.

The flat resin pipe 15 sent to the lower guide roller 7 is bent and formed by the lower guide roller 7, and then sent to the squeeze forming roller 8 where it is bent again. The flat resin pipe 15, which has been heated and softened, is gently bent by the upper guide roller 6, and then gradually bent by the lower guide roller 7 and squeeze forming roller 8, thereby forming the flat resin pipe. It is possible to bend and form the pipe 15 without applying excessive force. Therefore, the flat resin pipe 15 can be bent without causing internal wrinkles in the bent portion or changing its cross-sectional shape. During this bending, both ends of the flat resin pipe 15 are located at the relief portions 73 and 83 of the upper roller 71 of the lower guide roller 7 and the upper roller 81 of the squeeze forming roller 8, respectively. Molding can be performed without contacting rollers. Therefore, the voids 16 can be maintained inside both ends of the flat resin pipe 15 as they are.

The flat resin pipe 15 bent and formed by the squeeze forming roller 8 is sent to a concave vertical roller 9. The flat resin pipe 15 sent to the concave vertical roller 9 is sandwiched between a pair of left and right concave rolls 91 and 92 with a large radius of curvature, which are installed orthogonally to the squeeze forming roller 8, and are held at both ends in the width direction. are curved so that they are close to each other, and are formed into a double-walled cylindrical shape, as shown in FIG. Since the flat resin pipe 15 is bent upward by a squeeze forming roller 8 or the like when forming into this double-walled cylindrical shape, it can be easily bent. A flat resin pipe 15 formed into a double-walled cylindrical shape by a concave vertical roller 9 serves as a shielding plate 10 for the introduction guide hose 5.
and is introduced into the bellows pipe 14 installed inside the existing pipe 3. A double-walled cylindrical flat resin pipe 1 that is heated and pressurized to a softening temperature from above the shape recovery temperature to below the shape memory temperature.
When the pipe 5 is introduced into the bellows pipe 14, the heating and pressurization by the heated pressurized fluid is released, and the pipe 5 is cooled by coming into contact with the air in the existing pipe 3, and its temperature gradually decreases. When this temperature decreases, the double-walled cylindrical flat resin pipe 15 attempts to recover its shape and return to the cylindrical shape in which the shape was initially memorized. Therefore, recovery of this shape is suppressed by the bellows pipe 14 having a diameter smaller than the inner diameter of the existing pipe 3, and the flat resin pipe 15 is maintained in a double-walled cylindrical shape. For this reason, the length of the bellows pipe 14 is determined in advance so that the temperature of the flat resin pipe 15 at the final end is cooled to below the shape recovery temperature.

The cooled double-walled cylindrical flat resin pipe 15 is pulled by a pulling belt 17 and inserted into the existing pipe 3. When this flat resin pipe 15 is towed within the existing pipe 3, the flat resin pipe 15 is hardened while maintaining its double-walled circular shape, so it can be prevented from stretching or being damaged even if it is towed over a long distance. be able to. Furthermore, when the double-walled cylindrical flat resin pipe 15 passes through the bellows pipe 14,
Since the contact area with the bellows tube 14 is small, the frictional force can be reduced, and an increase in traction resistance can be suppressed.

After inserting the flat resin pipe 15 over the entire length of the existing pipe 3 in this way, the introduction guide hose 5 and the bellows tube 14 are removed, and the end of the flat resin pipe 15 is expanded using an expansion jig. Then, the existing pipe 3 is softened and expanded by supplying heated pressurized fluid to the inside of the flat resin pipe 15 or by moving a pipe expanding tool such as a pig while supplying the heated fluid.
The resin pipe 15 is brought into close contact with the inner surface. When softening and expanding this flat resin pipe 15, the flat resin pipe 1
The gaps 16 at both ends of the flat resin pipe 15 are used as a flow path for the heating fluid, and the portion beyond the expansion surface of the flat resin pipe 15 can be preheated.

[0030] In the above embodiment, the heated fluid generating device 11
The heating fluid generating device 11,
A case has been described in which the heating fluid outgoing hose 12, the introduction guide hose 5, the heated pressurized container 4, the heated fluid returning hose 13, and the heated fluid generator 11 are formed. When sending the fluid, the tip of the introduction guide hose 5 is opened as shown in FIG. You may do so. In this case, heated steam is sent from the heated fluid outbound hose 12 through the introduction guide hose 5 to the heated pressurized container 4, and is released from the open part at the tip to be placed between the introduction guide hose 5 and the existing pipe 3. While heating a certain flat resin pipe 15, heated steam is sent from the heated fluid outgoing hose 12 to the heated and pressurized container 4 and discharged from the drain pipe 18 provided at the bottom of the heated and pressurized container 4, thereby heating and pressurizing it. The flat resin pipe 15 inside the container 4 is heated and pressurized. By doing so, the temperature of the flat resin pipe 15 introduced into the existing pipe 3 can be lowered more quickly, and the length of the bellows pipe 14 can be shortened.

[0031]

Effects of the Invention As explained above, the present invention is a flat resin pipe which is obtained by flattening a thermoplastic resin pipe that has been shaped to have a shape memory by forming it to an outer diameter that is the same as or slightly smaller than the inner diameter of the existing pipe so that its cross-sectional area becomes smaller. The tube is drawn out through an introduction guide hose that circulates heated fluid, and is gently bent along the tube axis near the outlet of the heated and pressurized container with a pair of concave and convex forming rollers that have a large radius of curvature. By doing so, the flat resin pipe can be moved to the vicinity of the existing pipe without being bent or deformed.

[0032] Furthermore, the flat resin pipe that has been pulled down to the vicinity of the existing pipe is gradually bent and formed by a plurality of pairs of forming rollers whose radius of curvature becomes smaller, and then a plurality of pairs of forming rollers are used.
Since the resin pipe is bent into a double-walled cylindrical shape by using a concave roller perpendicular to the roller so that both ends in the width direction are close together, it can be bent without applying excessive stress to the resin pipe, eliminating internal wrinkles. It is possible to prevent deformation of the cross section.

Furthermore, when inserting a double-walled cylindrical resin pipe into an existing pipe, a bellows pipe having an inner diameter larger than the outer diameter of the double-walled cylindrical resin pipe is inserted from the existing pipe opening. By introducing the molded resin pipe into the existing pipe while suppressing its outer diameter with the inner wall of the bellows pipe, the residual heat from molding will cause the resin pipe to recover its shape and increase its outer diameter. This makes it possible to reduce the resistance when pulling the resin pipe inside the existing pipe. Therefore, long-distance construction can be carried out stably.

[0034] Furthermore, since the resin pipe was processed into a double-walled circular shape in the introduction guide hose installed at the construction site and introduced into the existing pipe, the resin pipe before construction was almost flat and was not attached to the drum. It can be rolled up or folded for storage. Therefore, long or thick resin pipes can be rolled up into small diameter pipes, making it possible to perform long-distance construction, and making it easier to store and transport resin pipes during construction. can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the invention.

FIG. 2 is a front view showing an upper guide roller.

FIG. 3 is a front view showing the lower guide roller.

FIG. 4 is a front view showing the squeeze forming roller.

FIG. 5 is a front view showing a concave vertical roller.

FIG. 6 is a perspective view showing a resin pipe.

FIG. 7 is a perspective view showing a flat resin pipe.

FIG. 8 is a sectional view showing another embodiment.

[Explanation of symbols]

1 Introduction device 3. Existing pipes 4 Heated and pressurized container 5 Introduction guide hose 6 Upper guide roller 7 Lower guide roller 8 Squeeze molding roller 9 Concave vertical roller 14 Bellows tube 15 Flat resin pipe

Claims (3)

[Claims] [Claim 1] A thermoplastic resin pipe that has been shaped to have an outer diameter that is the same as or slightly smaller than the inner diameter of the existing pipe and has a shape memory is flattened so that the cross-sectional area becomes smaller, and the flat resin pipe is guided and inserted into the existing pipe. In the resin pipe introduction method, a flat resin pipe pulled out from a heated and pressurized container is shaped along the tube axis by a pair of uneven forming rollers with a large radius of curvature, which are installed near the outlet of the heated and pressurized container. The flat resin pipe is gently bent and pulled down to the vicinity of the existing pipe while being heated and pressurized, and then the flat resin pipe is gradually bent using multiple pairs of forming rollers, which are installed near the mouth of the existing pipe and whose radius of curvature is gradually decreasing. After increasing the size, the flat resin pipe is formed into a curved shape using a concave roller having a rotation axis perpendicular to the rotation axis of the plurality of pairs of forming rollers so that both ends in the width direction are close to each other, and then introduced into the existing pipe. A resin pipe introduction method characterized by: [Claim 2] A bellows pipe having an inner diameter larger than the outer diameter of the curved resin pipe is installed for a certain length from the existing pipe port, and the outer diameter of the curved resin pipe is suppressed by the bellows pipe. The resin pipe introduction method according to claim 1, wherein the resin pipe is introduced into an existing pipe. [Claim 3] A thermoplastic resin pipe that has been shaped to have an outer diameter that is the same as or slightly smaller than the inner diameter of the existing pipe and has a shape memory is flattened to have a smaller cross-sectional area, and the flat resin pipe is guided and inserted into the existing pipe. A resin pipe introduction device includes an introduction guide hose that is attached between a heated and pressurized container containing a flat resin pipe and an existing pipe port, and guides the flat resin pipe while supplying heating fluid, and the introduction guide hose. A pair of concave and convex forming rollers with a large radius of curvature are installed near the outlet of the heated and pressurized container inside the tube. a plurality of pairs of forming rollers having rotating axes parallel to each other and having successively smaller radii of curvature; A resin pipe introducing device comprising a concave roller having a rotating shaft.