JP7703468B2 - Pipe cutting method and pipe inner surface cutting device - Google Patents

Description

The present invention relates to a pipe cutting method for cutting a pipe and a pipe inner surface cutting device for cutting the inner surface of a pipe in order to remove an existing pipe extending from a main pipe.

Gas, water, and other supplies to consumers are supplied from a main pipe buried underground under roads or land managed by a city, prefecture, or country through a branch pipe that extends to the consumer's private property. For example, in the case of gas supply, as shown in Figure 6, a main pipe 8 for gas supply is buried underground under a public road 7. A branch pipe 9 extends from the main pipe 8 toward the private property 6. The branch pipe 9 is connected to the consumer's building 10, and gas is supplied to the consumer. Note that pipes made of thermoplastic resin such as polyethylene are generally used for the branch pipe 9.

When demolishing a building 10 built on private land, the branch pipe 9 is removed before the demolition work begins in order to prevent accidents caused by gas leaks, etc. Here, the work of removing the branch pipe 9 will be explained using Figure 15. Figures 15(a) to (c) are diagrams showing the process of removing the branch pipe 9 using a pipe cutting method according to the prior art.

First, as shown in FIG. 15(a), a borehole 13 is drilled on private property 6 to expose the branch pipe 9. Next, as shown in FIG. 15(b), the branch pipe 9 is blocked with a squeeze tool 14, and then cut downstream of the squeeze tool 14. Next, as shown in FIG. 15(c), a cover member 19 is fused to the cut opening 91 to completely block it. In this way, the branch pipe 9 is removed with only a portion remaining, and after removal, the borehole 13 is filled in.

JP 2017-159405 A

To remove the branch pipe 9, a borehole 13 must first be drilled. However, before the demolition work of the building 10, the location of the borehole 13 is often limited because the building 10 on the private property 6, the plantings 11, and the parking lot 12 made of asphalt, concrete, etc. get in the way. As a result, the borehole 13 must be drilled away from the property boundary line B11, which is the boundary between the public road 7 and the private property 6. This can result in the length of the branch pipe 9 that remains after being cut (for example, the length L21 from the property boundary line B11 to the cut opening 91) becoming long.

Measures have been taken to prevent the remaining branch pipe 9 from being damaged during the demolition of the building 10 by indicating the buried position of the remaining branch pipe 9, for example by installing gas pipe marking posts. However, there is a risk that the existence of the remaining branch pipe 9 will be forgotten as workers are replaced depending on the work process of the demolition work, and therefore if the length L21 of the remaining branch pipe 9 is long, the branch pipe 9 is more likely to be damaged during the demolition work. In light of the above, it is desirable to cut the branch pipe 9 as close to the site boundary line B11 as possible and shorten the length of the remaining branch pipe 9 (the length from the site boundary line B11 to the cut opening 91).

The present invention is intended to solve the above problems, and aims to provide a pipe cutting method that can cut an existing pipe extending from a main pipe as close as possible to the site boundary line.

In order to solve the above problems, the pipe cutting method and the pipe inner surface cutting device of the present invention have the following configuration.
(1) A pipe cutting method for cutting an existing pipe made of thermoplastic resin extending from a main pipe in order to remove the pipe, comprising the steps of: drilling a hole at a position where the pipe is buried; exposing the pipe; blocking the exposed pipe with a squeeze tool; making a first cut on the pipe downstream of the squeeze tool; removing the squeeze tool from the pipe; inserting an elastic seal member from a cut opening formed by the first cut of the pipe to a predetermined position on the pipe to temporarily block the pipe; inserting a pipe inner surface cutting device from the cut opening to cut an inner surface of the pipe; The pipe inner surface cutting device is moved from the position where the pipe inner surface cutting device was inserted toward the cutting opening to cut the downstream side of the elastic seal member, thereby removing impurities adhering to the inner circumferential surface, and after removing the pipe inner surface cutting device from the cutting opening, a plug member made of thermoplastic resin is inserted into the pipe from the cutting opening to fuse the plug member to the portion of the inner circumferential surface that was cut by the pipe inner surface cutting device to block the pipe, and a pipe inner surface cutter is inserted into the pipe from the cutting opening to perform a second cut of the pipe downstream of the position where the plug member was fused by the pipe inner surface cutter. Note that the above-mentioned predetermined position is appropriately set depending on the target length of the cut pipe.

According to the pipe cutting method described in (1), instead of blocking the pipe using the cover member 19 used in the past, a plug member made of thermoplastic resin is inserted into the pipe from the cut opening formed by the first cut, and the plug member is fused to the inner surface of the pipe to block the pipe. Then, a pipe inner surface cutter is inserted into the pipe from the cut opening, and a second cut of the pipe is made downstream of the position where the plug member was fused using the pipe inner surface cutter. Therefore, the pipe can be cut at a position closer to the main pipe than the borehole. Being closer to the main pipe means that the pipe can be cut at a position closer to the property line, which reduces the risk of damaging the pipe remaining underground, for example, during demolition work on a building.

Oxide films and other impurities adhere to the inner surface of existing pipes over time. If an attempt is made to fuse a plug member to the inner surface of the pipe without removing these impurities, the fusion will be incomplete, and there is a risk of leakage of the fluid (e.g., gas) flowing through the pipe. In this regard, according to the pipe cutting method described in (1), a pipe inner surface cutting device that cuts the inner surface of the pipe is inserted from the cutting opening, and the inner surface of the pipe is cut by the pipe inner surface cutting device, thereby removing the impurities. Then, a plug member is fused to the part from which the impurities have been removed by the cutting, so that the fusion can be performed reliably.

(2) A pipe cutting method for cutting an existing pipe made of thermoplastic resin extending from a main pipe in order to remove the pipe, comprising the steps of: drilling a hole at a position where the pipe was buried, exposing the pipe, blocking the exposed pipe with a squeeze tool, making a first cut of the pipe downstream of the squeeze tool, removing the squeeze tool from the pipe, inserting an elastic seal member from a cut opening formed by the first cut of the pipe to a predetermined position of the pipe to temporarily block the pipe, inserting a pipe inner surface cutting device from the cut opening to cut an inner circumferential surface of the pipe, cutting a downstream side of the elastic seal member of the inner circumferential surface with the pipe inner surface cutting device, inserting a plug member made of thermoplastic resin into the pipe from the cut opening to temporarily block the inner circumferential surface of the pipe the tube is blocked by fusing the plug member to the portion cut by the internal cutting device, a tube internal cutter is inserted into the tube from the cutting opening, and a second cut of the tube is made by the tube internal cutter downstream of the position where the plug member was fused; the tube internal cutting device comprises a cutting head insertable into the tube, a rotating device used outside the tube, and a flexible shaft that transmits the rotational force of the rotating device to the cutting head and rotates the cutting head; the cutting head comprises a pair of cutting blades positioned symmetrically with respect to the rotation axis of the cutting head, and a biasing means for biasing each of the pair of cutting blades outward in the rotational radius direction of the cutting head and pressing them against the inner circumferential surface in a direction perpendicular to the tube axis of the tube.

(3) In the tube cutting method described in (2), the biasing means generates a biasing force in a direction parallel to the rotation axis, and at least one of the biasing means and the pair of cutting blades has a deflection section consisting of an inclined surface that intersects obliquely with the direction of the rotation axis and the direction of the rotation radius, and the biasing force is deflected by the deflection section into a force in the direction of the rotation radius and transmitted to the pair of cutting blades.

(4) In the tube cutting method described in (2) or (3), the cutting head cuts the inner surface while moving along the tube axis, the outer periphery of the cutting head forward of the pair of cutting blades in the direction of movement is covered by a cylindrical positioning roller, and the positioning roller is fixed coaxially with the rotation axis and rotatably relative to the cutting head.

(5) The tube cutting method according to any one of (2) to (4) is characterized in that it includes a feed device disposed between the rotating device and the tube, which feeds the flexible shaft in the axial direction of the flexible shaft to move the cutting head inserted into the tube at a constant speed along the tube axis of the tube.

(6) A pipe inner surface cutting device for inserting a cutting opening formed by cutting an existing pipe made of thermoplastic resin extending from a main pipe into a drilled hole, and cutting the inner surface of the pipe to form a surface for welding a plug member made of thermoplastic resin , the device comprising: a cutting head insertable into the pipe; a rotating device used outside the pipe; and a flexible shaft for transmitting the rotational force of the rotating device to the cutting head and rotating the cutting head, the cutting head comprising a pair of cutting blades positioned symmetrically with respect to the rotation axis of the cutting head, and a biasing means for biasing each of the pair of cutting blades outward in the direction of the rotation radius of the cutting head and pressing them against the inner surface in a direction perpendicular to the pipe axis of the pipe.

(7) In the tube inner surface cutting device described in (6), the biasing means generates a biasing force in a direction parallel to the rotation axis, at least one of the biasing means and the pair of cutting blades has a deflection part consisting of an inclined surface that intersects obliquely with the direction of the rotation axis and the direction of the rotation radius, and the biasing force is deflected by the deflection part into a force in the direction of the rotation radius and transmitted to the pair of cutting blades.

(8) In the tube inner surface cutting device described in (6) or (7), the cutting head cuts the inner surface while moving along the tube axis, the outer periphery of the cutting head forward of the pair of cutting blades in the direction of movement is covered by a cylindrical positioning roller, and the positioning roller is fixed coaxially with the rotation axis and rotatably relative to the cutting head.

(9) The tube inner surface cutting device according to any one of (6) to (8) is characterized in that it includes a feed device disposed between the rotating device and the tube, which feeds the flexible shaft in the axial direction of the flexible shaft to move the cutting head inserted into the tube at a constant speed along the tube axis of the tube.

Conventionally, as an example of a pipe inner surface cutting device for cutting the inner surface of a pipe, the pipe inner surface cutting device disclosed in Patent Document 1 is known. However, this device requires a boring bar with a length corresponding to the distance to insert the cutting head into the pipe, so if the boring bar is long, the pipe inner surface cutting device cannot be brought into the limited space of a borehole, or even if it can be brought in, it becomes difficult to insert the cutting head into the pipe. Furthermore, since a supply of hydraulic oil is required to bring the cutting blade into contact with the inner surface of the pipe, a separate device for supplying hydraulic oil is required, making it difficult to use in the limited space of a borehole.

In this regard, according to the pipe cutting method described in any one of (2) to (5) or the pipe inner surface cutting device described in any one of (6) to (9), the cutting head rotates by the rotational force of the rotating device used outside the pipe transmitted by the flexible shaft, so that, for example, by winding up the flexible shaft, the pipe inner surface cutting device can be easily carried into the limited space of a drilling hole. Then, when inserting the cutting head into the pipe, the wound flexible shaft can be fed out as it is inserted. Therefore, even in the limited space of a drilling hole, the work of inserting the cutting head into the pipe is easy. Furthermore, since the biasing means provided on the cutting head biases the cutting blade outward in the direction of the rotation radius of the cutting head and presses it against the inner surface of the pipe from a direction perpendicular to the pipe axis of the pipe, no separate device is required to bring the cutting blade into contact with the inner surface of the pipe. Therefore, the pipe inner surface cutting device can be easily used in the limited space of a drilling hole.

The pipe cutting method or pipe inner surface cutting device of the present invention makes it possible to cut an existing pipe extending from a main pipe as close as possible to the site boundary line.

FIG. 2 is a diagram showing the configuration of a pipe inner surface cutting device. FIG. FIG. 2 is a plan view of the cutting head, with a portion shown in partial cross section. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, illustrating the cutting blade and the biasing means. FIG. 13 is a diagram showing a state in which the cutting head is inserted into a branch pipe. FIG. 2 is a diagram showing the buried state of a main pipe and a branch pipe for gas supply. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. 10A to 10C are diagrams showing a process of removing a branch pipe by the pipe cutting method according to the embodiment. FIG. 2 is a diagram illustrating a delivery device. 1A to 1C are diagrams showing a process for removing a branch pipe by a pipe cutting method according to the prior art.

(About the tube inner surface cutting device)
First, an embodiment of a pipe inner surface cutting device 1 according to the present invention will be described with reference to Figs. 1 to 6. Fig. 1 is a diagram showing the configuration of the pipe inner surface cutting device 1. Fig. 2 is a front view of the cutting head 2. Fig. 3 is a plan view of the cutting head 2, with a portion shown in partial cross section. Fig. 4 is a cross-sectional view taken along line A-A in Fig. 3, and is a diagram for explaining the cutting blades 22, 23 and the biasing means 26. Fig. 5 is a diagram showing the state in which the cutting head 2 is inserted into a branch pipe 9 (an example of a pipe).

As shown in FIG. 1, the tube inner surface cutting device 1 includes a cutting head 2, an electric screwdriver 3 (an example of a rotation device), and a flexible shaft 4 (an example of a flexible shaft) that connects the cutting head 2 and the electric screwdriver 3.

The electric screwdriver 3 is a typical electric screwdriver, and a motor (not shown) built into the electric screwdriver 3 is driven by a battery 31 as a power source, and the rotational force of the motor is output by an output mechanism 32.

The flexible shaft 4 comprises a hose-shaped outer tube 41 and a flexible rotating shaft (not shown; hereafter referred to as the flexible rotating shaft) inserted into the inside of the outer tube 41. The flexible rotating shaft has a driving side shaft end 42 at the end of the electric screwdriver 3 and a driven side shaft end 43 at the other end of the axial direction. The driving side shaft end 42 and the driven side shaft end 43 protrude from the outer tube 41, the driving side shaft end 42 is connected to the output mechanism 32 of the electric screwdriver 3, and the driven side shaft end 43 is connected to the cutting head 2. When a rotational force is output from the output mechanism 32 of the electric screwdriver 3, the flexible rotating shaft rotates inside the outer tube 41.

As shown in Figures 2 and 3, the cutting head 2 comprises a cutting head body 21, a pair of cutting blades 22, 23, and a positioning roller 24. In the following description, of both ends of the cutting head 2 in the direction of the rotation axis A11 in Figures 2 and 3, the left end side (the side connected to the driven shaft end 43 of the flexible shaft 4) is referred to as the axial rear end, and the right end side is referred to as the axial tip.

The cutting head body 21 is formed into a cylindrical shape from stainless steel or the like, and its central axis is the rotation axis A11. When the rotational force generated by the electric screwdriver 3 is transmitted to the cutting head body 21 by the flexible shaft 4, the cutting head body 21 rotates around the rotation axis A11.

The cutting head body 21 has a cylindrical hollow portion 211 that is coaxial with the cutting head body 21. The hollow portion 211 opens at the axial rear end side of the cutting head body 21, providing an opening 212 in the cutting head body 21. A connecting member 25 for connecting the driven shaft end portion 43 of the flexible shaft 4 is fixed to the opening 212.

The connecting member 25 is formed in a cylindrical shape and is fixed to the opening 212 of the cutting head body 21 while being positioned coaxially with the cutting head body 21. A hexagonal hole 251 is drilled coaxially with the connecting member 25 toward the axial tip end of the connecting member 25 on the end face of the connecting member 25 opposite the cutting head body 21. Furthermore, a through-threaded hole 252 communicating with the hexagonal hole 251 is provided on the outer circumferential surface of the connecting member 25. The driven shaft end 43 of the flexible shaft 4 can be inserted into the hexagonal hole 251, and the driven shaft end 43 inserted into the hexagonal hole 251 is fixed to the hexagonal hole 251 by a screw (not shown) screwed into the through-threaded hole 252. Since the driven shaft end 43 is fixed to the hexagonal hole 251, when the flexible shaft 4 is rotated by the electric driver 3, the cutting head body 21 is rotated around the rotation axis A11.

The hollow portion 211 of the cutting head body 21 contains a biasing means 26. The biasing means 26 includes a coil spring 261 for generating a biasing force and a pressing member 262 for transmitting the biasing force to the cutting blades 22 and 23.

The pressing member 262 is formed in a cylindrical shape. Its diameter is smaller than the diameter of the hollow portion 211, and it can slide inside the hollow portion 211 in the direction of the rotation axis A11 of the cutting head body 21. When the pressing member 262 slides, the inner peripheral surface of the hollow portion 211 serves as a guide.

In addition, an insertion hole 264 into which the coil spring 261 can be inserted is drilled toward the axial tip end in the end face of the pressing member 262 on the axial rear end side. The bottom surface 265 on the tip side of the insertion hole 264 abuts against the end on the axial tip side of the coil spring 261 inserted into the insertion hole 264.

The coil spring 261 is disposed coaxially with the hollow portion 211. Of the two ends in the rotation axis direction, the rear end abuts against the end face 253 on the tip side of the connecting member 25, and the coil spring 261 is in a compressed state by the bottom face 265 of the pressing member 262 and the end face 253 of the connecting member 25. Therefore, the coil spring 261 generates a biasing force in a direction parallel to the rotation axis A11.

The tip of the pressing member 262 is provided with an inclined surface that intersects obliquely with the direction of the rotation axis A11 and the direction of the rotation radius, and this inclined surface is a deflection section 263 for deflecting the direction of the biasing force of the coil spring 261 to the direction of the rotation radius. The angle X of the deflection section 263 (inclined surface) is not particularly limited, but in this embodiment, it is 45 degrees with respect to the rotation axis A11.

A cutting blade holding part 213 having a substantially rectangular parallelepiped shape is erected on the end face of the cutting head body 21 at the axial tip side. The center of the cutting blade holding part 213 having a substantially rectangular parallelepiped shape is located on the rotation axis A11. The cutting blade holding part 213 also has a slit 214, in which a pair of cutting blades 22, 23 are housed so as to be slidable in the direction of the rotation radius (the up and down direction in FIG. 2 or FIG. 4). Furthermore, four screws 281 are inserted in a line perpendicular to the rotation axis A11 nearer to the tip of the cutting blade holding part 213 than the center in the direction of the rotation axis A11, and four miniature bearings 28 are fixed in the slit 214 by each of the four screws 281. Furthermore, two screws 271 are inserted side by side perpendicular to the rotation axis A11 toward the rear end of the cutting blade holding part 213 from the center in the direction of the rotation axis A11, and two miniature bearings 27 are fixed in the slits 214 by each of the two screws 271.

The cutting blades 22, 23 have their outer ends in the direction of the rotation radius protruding from the cutting blade holder 213, and the protruding ends are equipped with blades 221, 231 for cutting the inner surface 92 of the branch pipe 9.

The cutting blades 22, 23 are provided with oval holes 222, 232, the longitudinal direction of which is parallel to the direction of the radius of rotation of the cutting head 2, penetrating the thickness direction of the cutting blades 22, 23. Miniature bearings 27 fixed in the slits 214 are located in the oval holes 222, 232. Furthermore, two miniature bearings 28 fixed in the slits 214 are in contact with the end faces of the axial tip side of the cutting blades 22, 23. The cutting blades 22, 23 are guided by these miniature bearings 27, 28 and can slide within the range of the longitudinal length of the oval holes 222, 232 in the direction of the radius of rotation of the cutting head 2 (the up-down direction in FIG. 2 or FIG. 4).

At the rear end of the axial end where the pair of cutting blades 22, 23 face each other, there is provided an inclined surface that intersects obliquely with the direction of the rotation axis A11 and the direction of the rotation radius, and this inclined surface is a deflection section 223, 233 for deflecting the direction of the biasing force of the coil spring 261. The angle X of the deflection section 223, 233 (inclined surface) is 45 degrees with respect to the rotation axis A11, similar to the deflection section 263. The deflection section 263 of the pressing member 262, which is biased toward the axial tip side by the biasing force of the coil spring 261, abuts against the deflection section 223, 233. The biasing force of the coil spring 261 is deflected by the deflection sections 223, 233, 263 into a force in the direction of the rotation radius, so that each of the pair of cutting blades 22, 23 is biased outward in the direction of the rotation radius (up and down direction in FIG. 4). In this embodiment, both the cutting blades 22, 23 and the pressing member 262 of the biasing means 26 are provided with the deflection portions 223, 233, 263, but it is also possible to provide a deflection portion (i.e., an inclined surface) on either the cutting blades 22, 23 or the pressing member 262.

The positioning roller 24 is formed in a cylindrical shape and covers the outer peripheral surface 215 of the cutting head body 21 on the axial rear side of the pair of cutting blades 22, 23 while being positioned coaxially with the rotation axis A11. A needle bearing 29 is disposed between the outer peripheral surface 215 of the cutting head body 21 and the inner peripheral surface 242 of the positioning roller 24, so that the positioning roller 24 can rotate with respect to the cutting head body 21. The rotation axis of the positioning roller 24 is coaxial with the rotation axis A11. The diameter of the positioning roller 24 is larger than the diameter of the maximum outer diameter part 216 of the cutting head body 21 and slightly smaller than the inner diameter of the branch pipe 9 (for example, 32.85 to 34.35 mm). As a result, the cutting head 2 is positioned so that the rotation axis A11 of the cutting head 2 is approximately the same as the pipe axis of the branch pipe 9.

In the above-described pipe inner surface cutting device 1, when the cutting head 2 is inserted into the inside of the branch pipe 9 from the opening (e.g., the cutting opening 91) of the branch pipe 9, as shown in FIG. 5, the cutting blades 22 and 23, which are biased outward in the direction of the rotation radius by the biasing means 26, are pressed against the inner circumferential surface 92 of the branch pipe 9 from a direction perpendicular to the pipe axis of the branch pipe 9. Then, when the cutting head 2 is rotated by the rotational force of the electric screwdriver 3, the cutting blades 22 and 23 cut the inner circumferential surface 92 of the branch pipe 9. This cutting is performed while the cutting head 2 moves from the inserted position in the branch pipe 9 toward the opening (cutting opening 91) along the pipe axis of the branch pipe 9, as shown by the arrow Y11. The movement of the cutting head 2 in the direction of the arrow Y11 may be performed by an operator on the opening (cutting opening 91) side pulling the flexible shaft 4, or may be performed by feeding the flexible shaft 4 by a feeding device 5 (see FIG. 14) described later. The chips generated by cutting are left behind in the direction of movement of the cutting head 2. The chips are removed by blowing air or by the worker scraping them out.

(About pipe cutting method)
Next, an embodiment of the pipe cutting method according to the present invention will be described with reference to Figures 6 to 13. Figure 6 is a diagram showing the buried state of a main pipe 8 and a branch pipe 9 for gas supply. Figures 7 to 13 are diagrams showing the process of removing the branch pipe 9 by the pipe cutting method according to this embodiment. Figure 14 is a diagram for explaining a delivery device 18.

Gas is supplied to consumers through a branch pipe that extends from a main pipe buried underground on roads or land managed by a city, prefecture, or country to the consumer's private property. For example, as shown in FIG. 6, a main pipe 8 for gas supply is buried underground on a public road 7. A branch pipe 9 extends from the main pipe 8 toward private property 6. The branch pipe 9 is connected to the consumer's building 10, so gas is supplied to the consumer. Note that a pipe made of a thermoplastic resin such as polyethylene is generally used for the branch pipe 9. The pipe cutting method according to this embodiment will be described using the process of removing the branch pipe 9 buried in private property 6 as an example.

First, as shown in FIG. 7, a borehole 13 is provided on private property 6, and a branch pipe 9 is exposed. The borehole 13 is provided to avoid buildings 10, plants 11, parking lots 12 made of asphalt or concrete, and the like on private property 6. Here, for example, the borehole 13 is provided between the building 10 and the parking lot 12. The size of the borehole 13 is appropriately set to a size that allows an operator to work inside the borehole 13.

Next, as shown in FIG. 8, the exposed branch pipe 9 is blocked with a squeeze tool 14, and then the branch pipe 9 is cut on the downstream side of the squeeze tool 14 (first cut). The squeeze tool 14 used is a general squeeze tool that compresses and deforms the branch pipe 9 from the outside, blocking the branch pipe 9 and cutting off the gas. The cut downstream side of the branch pipe 9 will be removed during the demolition work of the building 10, but is not shown in FIG. 8 to FIG. 14.

Next, as shown in FIG. 9, an elastic seal member 15 is attached to the cut opening 91 formed by the first cut. This is to prevent gas from leaking from the cut opening 91 when the squeeze tool 14 is removed. In order to attach the elastic seal member 15 to the cut opening 91, it is necessary to ensure a sufficient distance between the cut opening 91 and the squeeze tool 14 (for example, several tens of centimeters). The elastic seal member 15 is, for example, a rubber stopper made of polyethylene.

Next, the squeeze tool 14 is removed from the branch pipe 9, and as shown in FIG. 10, the elastic seal member 15 is inserted, for example, up to the vicinity of the property boundary line B11 on the private property 6 side. The diameter of the elastic seal member 15 is made slightly larger than the inner diameter of the branch pipe 9, and it is pressed into the branch pipe 9. This pressing blocks the gas flowing through the branch pipe 9. Note that the elastic seal member 15 is removable from the branch pipe 9, and does not completely block the branch pipe 9. Therefore, here, the blocking of gas by the elastic seal member 15 is referred to as a temporary blockage of the branch pipe 9.

Next, as shown in FIG. 11, the cutting head 2 of the pipe inner surface cutting device 1 is inserted into the branch pipe 9 from the cutting opening 91. Then, the electric screwdriver 3 is operated to rotate the cutting head 2 inside the branch pipe 9, and the inner surface 92 of the branch pipe 9 is cut downstream of the elastic seal member 15.

Conventionally, as an example of a pipe inner surface cutting device for cutting the inner surface of a pipe, the pipe inner surface cutting device disclosed in Patent Document 1 is known. However, this device requires a boring bar with a length corresponding to the distance to which the cutting head is inserted into the pipe. Therefore, if the boring bar is long, the pipe inner surface cutting device cannot be brought into the limited space of a borehole, or even if it can be brought in, it becomes difficult to insert the cutting head into the pipe. Furthermore, since a supply of hydraulic oil is required to bring the cutting blade into contact with the inner surface of the pipe, a separate device for supplying hydraulic oil is required, making it difficult to use in the limited space of a borehole.

In this regard, according to the pipe cutting method or pipe inner surface cutting device 1 of this embodiment, the cutting head 2 rotates by the flexible shaft 4, so that, for example, by winding up the flexible shaft 4, the pipe inner surface cutting device 1 can be easily brought into the limited space of the drilling hole 13. Then, when inserting the cutting head 2 into the branch pipe 9, the flexible shaft 4 in the wound state can be fed out as it is inserted. Therefore, even in the limited space of the drilling hole 13, the work of inserting the cutting head 2 into the branch pipe 9 is easy. Furthermore, the biasing means 26 provided on the cutting head 2 biases the cutting blades 22, 23 outward in the direction of the rotation radius of the cutting head 2 and presses them against the inner circumferential surface 92 of the branch pipe 9, so that no separate device is required to bring the cutting blades 22, 23 into contact with the inner circumferential surface 92 of the branch pipe 9. Therefore, the pipe inner surface cutting device 1 can be easily used in the limited space of the drilling hole 13.

In addition, because the branch pipe 9 is made of polyethylene, it may be buried in a bent state. Even in such a case, the pipe inner surface cutting device 1 is able to cut the inner surface 92 by following the bent branch pipe 9 due to the flexibility of the flexible shaft 4.

Cutting by the cutting head 2 is performed while the cutting head 2 moves from the inserted position in the branch pipe 9 toward the cutting opening 91 along the pipe axis of the branch pipe 9. The cutting chips generated by cutting are left behind in the direction in which the cutting head 2 moves. The remaining cutting chips are removed by air blowing or by the operator scraping them out.

The cutting head 2 can be moved by an operator on the cutting opening 91 side pulling the flexible shaft 4, or by feeding the flexible shaft 4 using the feeding device 5 shown in FIG. 14.

The delivery device 5 is composed of a base 181 erected in the borehole 13 and a holding jig 182 that holds the flexible shaft 4. The base 181 has a fixing portion 183 for fixing the base 181 to the bottom of the borehole 13. The base 181 also has a gripping portion 184 that grips the branch pipe 9 so as not to cause a positional shift with respect to the branch pipe 9. The base 181 also has a drive mechanism, which allows the holding jig 182 to move at a constant speed on the base 181 along the axial direction of the flexible shaft 4 (the direction shown by the arrow Y12 in FIG. 14). Therefore, the holding jig 182 holding the flexible shaft 4 moves toward the upper end side of the base 181 opposite to the bottom side of the borehole 13, whereby the flexible shaft 4 is delivered in the axial direction of the flexible shaft 4, and the cutting head 2 is moved at a constant speed along the pipe axis of the branch pipe 9 toward the cutting opening 91. The moving speed of the holding jig 182 on the pedestal 181 is appropriately set based on the rotation speed of the cutting head 2 at a speed that allows the inner surface 92 of the branch pipe 9 to be cut uniformly. The pedestal 181 is also set at an inclined angle to the bottom surface of the drilling hole 13 in order to make the bending radius of the flexible shaft 4 gentle. However, this does not exclude setting the pedestal 181 at a right angle to the bottom surface of the drilling hole 13.

Next, as shown in FIG. 12, a plug member 16 made of thermoplastic resin is inserted into the branch pipe 9 from the cut opening 91. At this time, the plug member 16 is inserted up to a position adjacent to the downstream side of the elastic seal member 15. The plug member 16 is, for example, an electric fusion plug disclosed in JP 2021-1618 A, and is fused to the portion of the inner surface 92 of the branch pipe 9 that has been cut by the pipe inner surface cutting device 1. This closes the branch pipe 9 and blocks the gas.

Oxide films and other impurities adhere to the inner surface 92 of the existing branch pipe 9 due to long-term use. If an attempt is made to fuse the plug member 16 to the inner surface 92 of the branch pipe 9 without removing these impurities, the fusion will be incomplete and gas leakage may occur. In this regard, according to the pipe cutting method of this embodiment, the inner surface 92 of the branch pipe 9 is cut by the pipe inner surface cutting device 1, so that the impurities are removed. Then, the plug member 16 is fused to the part from which the impurities have been removed by the cutting, so that the fusion can be performed reliably.

Next, as shown in FIG. 13, the pipe inner surface cutter 17 is inserted into the branch pipe 9 from the cutting opening 91, and the pipe inner surface cutter 17 cuts the branch pipe 9 downstream of the position where the plug member 16 is fused (second cut). The cutting position is near the downstream end of the plug member 16.

According to the conventional pipe cutting method, the length L21 (see FIG. 15(c)) of the cut branch pipe 9 depends on the position of the drilled hole 13, and is about 50 to 60 cm even if it is as short as possible. However, according to the pipe cutting method according to the present embodiment, the elastic seal member 15 is positioned near the site boundary line B11, and the second cut is performed near the downstream end of the plug member 16 located adjacent to the elastic seal member 15, so that the length L11 of the remaining branch pipe 9 (the length from the site boundary line B11 to the cut opening 91) is approximately the sum of the length of the elastic seal member 15 and the length of the plug member 16 (about 20 to 30 cm). In this way, the branch pipe 9 can be cut at a position closer to the site boundary line B11, which reduces the risk of damaging the remaining branch pipe 9, for example, during demolition work of the building 10.

The remaining length L11 of the branch pipe 9 can be further shortened by positioning the elastic seal member 15 and plug member 16 further back in the branch pipe 9. In other words, the positions of the elastic seal member 15 and plug member 16 in the branch pipe 9 are appropriately set according to the target length L11. Also, leaving the branch pipe 9 protruding by the length L11 on the private property 6 side is the case when there is a possibility that the branch pipe 9 will be reused due to rebuilding the building 10, etc. Therefore, if there are no plans to reuse the branch pipe 9, the elastic seal member 15 and plug member 16 may be inserted into the branch pipe 9 to a position where the second cut can be made on the road 7 side of the property boundary line B11.

As described above, according to the pipe cutting method and the pipe inner surface cutting device 1 of the present embodiment,
(1) In a pipe cutting method for cutting a pipe (branch pipe 9) in order to remove an existing pipe (branch pipe 9) made of a thermoplastic resin extending from a main pipe 8, a drilling hole 13 is provided at a position where the pipe (branch pipe 9) is buried, the pipe (branch pipe 9) is exposed, the exposed pipe (branch pipe 9) is blocked by a squeeze tool 14, a first cut is made on the pipe (branch pipe 9) downstream of the squeeze tool 14, the squeeze tool 14 is removed from the pipe (branch pipe 9), and an elastic seal member 15 is inserted from a cut opening 91 formed by the first cut of the pipe (branch pipe 9) to a predetermined position of the pipe (branch pipe 9) (for example, near the property boundary line B11 on the private land 6 side) to thereby remove the pipe ( The method is characterized in that the pipe (branch pipe 9) is temporarily blocked, a pipe inner surface cutting device 1 for cutting an inner peripheral surface 92 of the pipe (branch pipe 9) is inserted from a cutting opening 91, the pipe inner surface cutting device 1 cuts the inner peripheral surface 92 downstream of the elastic seal member 15, a plug member 16 made of thermoplastic resin is inserted into the pipe (branch pipe 9) from the cutting opening 91, and the plug member 16 is fused to the portion of the inner peripheral surface 92 cut by the pipe inner surface cutting device 1 to block the pipe (branch pipe 9), a pipe inner surface cutter 17 is inserted into the pipe (branch pipe 9) from the cutting opening 91, and the pipe (branch pipe 9) is second cut by the pipe inner surface cutter 17 downstream of the position where the plug member 16 is fused. Note that the above-mentioned predetermined position is appropriately set according to the target length L11 of the pipe (branch pipe 9) remaining after cutting.

According to the pipe cutting method described in (1), the pipe (branch pipe 9) is not blocked using the cover member 19 used in the past, but a plug member 16 made of thermoplastic resin is inserted into the pipe (branch pipe 9) from the cutting opening 91 formed by the first cut, and the plug member 16 is fused to the inner peripheral surface 92 of the pipe (branch pipe 9) to block the pipe (branch pipe 9). Then, a pipe inner surface cutter 17 is inserted into the pipe (branch pipe 9) from the cutting opening 91, and the pipe (branch pipe 9) is cut secondly downstream of the position where the plug member 16 is fused by the pipe inner surface cutter 17. Therefore, the pipe (branch pipe 9) can be cut at a position closer to the main pipe 8 than the excavation hole 13. Close to the main pipe 8 means that the pipe (branch pipe 9) can be cut at a position closer to the site boundary line B11, and the risk of damaging the pipe (branch pipe 9) remaining in the ground during demolition work of the building 10, for example, is reduced.

Oxide films and other impurities adhere to the inner surface 92 of the existing pipe (branch pipe 9) due to long-term use. If the plug member 16 is fused to the inner surface 92 of the pipe (branch pipe 9) without removing these impurities, the fusion may be incomplete, and fluid (e.g., gas) flowing through the pipe (branch pipe 9) may leak. In this regard, according to the pipe cutting method described in (1), a pipe inner surface cutting device 1 that cuts the inner surface 92 of the pipe (branch pipe 9) is inserted from the cutting opening 91, and the inner surface 92 of the pipe (branch pipe 9) is cut by the pipe inner surface cutting device 1, thereby removing the impurities. Then, the plug member 16 is fused to the part from which the impurities have been removed by the cutting, so that the fusion can be performed reliably.

(2) In the pipe cutting method described in (1), the pipe inner surface cutting device 1 is characterized in that it comprises a cutting head 2 that can be inserted into the pipe (branch pipe 9), a rotating device (electric screwdriver 3) used outside the pipe (branch pipe 9), and a flexible shaft (flexible shaft 4) that transmits the rotational force of the rotating device (electric screwdriver 3) to the cutting head 2 and rotates the cutting head 2, and the cutting head 2 comprises a pair of cutting blades 22, 23 positioned symmetrically with respect to the rotation axis A11 of the cutting head 2, and a biasing means 26 that biases each of the pair of cutting blades 22, 23 outward in the rotation radius direction of the cutting head 2 and presses them against the inner circumferential surface 92 from a direction perpendicular to the pipe axis of the pipe (branch pipe 9).

(3) In the tube cutting method described in (2), the biasing means 26 generates a biasing force in a direction parallel to the rotation axis A11, at least one of the biasing means 26 and the pair of cutting blades 22, 23 has a deflection section 223, 233, 263 consisting of an inclined surface that intersects obliquely with the direction of the rotation axis A11 and the direction of the rotation radius, and the biasing force is deflected into a force in the direction of the rotation radius via the deflection section 223, 233, 263 and transmitted to the pair of cutting blades 22, 23.

(4) In the tube cutting method described in (2) or (3), the cutting head 2 cuts the inner surface 92 while moving along the tube axis, the outer periphery of the cutting head 2 forward of the pair of cutting blades 22, 23 in the direction of movement is covered by a cylindrical positioning roller 24, and the positioning roller 24 is fixed coaxially with the rotation axis A11 and rotatably relative to the cutting head 2.

(5) The pipe cutting method according to any one of (2) to (4) is characterized by including a feed device 5 that is disposed between the rotating device (electric screwdriver 3) and the pipe (branch pipe 9) and feeds the flexible shaft 4 in the axial direction of the flexible shaft 4, thereby moving the cutting head 2 inserted into the pipe (branch pipe 9) at a constant speed along the pipe axis of the pipe (branch pipe 9).

(6) A pipe inner surface cutting device 1 for cutting the inner peripheral surface 92 of a pipe (branch pipe 9) is characterized in that it comprises a cutting head 2 that can be inserted into the pipe (branch pipe 9), a rotating device (electric screwdriver 3) used outside the pipe (branch pipe 9), and a flexible shaft (flexible shaft 4) that transmits the rotational force of the rotating device (electric screwdriver 3) to the cutting head 2 and rotates the cutting head 2, the cutting head 2 comprises a pair of cutting blades 22, 23 positioned symmetrically with respect to the rotation axis A11 of the cutting head 2, and a biasing means 26 that biases each of the pair of cutting blades 22, 23 outward in the direction of the rotation radius of the cutting head 2 and presses them against the inner peripheral surface 92 from a direction perpendicular to the pipe axis of the pipe (branch pipe 9), and the pipe (branch pipe 9) is made of a thermoplastic resin.

(7) In the tube inner surface cutting device 1 described in (6), the biasing means 26 generates a biasing force in a direction parallel to the rotation axis A11, at least one of the biasing means 26 or the pair of cutting blades 22, 23 has a deflection section 223, 233, 263 consisting of an inclined surface that intersects obliquely with the direction of the rotation axis A11 and the direction of the rotation radius, and the biasing force is deflected via the deflection section 223, 233, 263 into a force in the direction of the rotation radius and transmitted to the pair of cutting blades 22, 23.

(8) In the tube inner surface cutting device 1 described in (6) or (7), the cutting head 2 cuts the inner surface 92 while moving along the tube axis, the outer periphery of the cutting head 2 forward of the pair of cutting blades 22, 23 in the direction of movement is covered by a cylindrical positioning roller 24, and the positioning roller 24 is fixed coaxially with the rotation axis A11 and rotatably relative to the cutting head 2.

(9) The pipe inner surface cutting device 1 described in any one of (6) to (8) is characterized in that it is provided with a feed device 5 that is disposed between the rotation device (electric driver 3) and the pipe (branch pipe 9) and feeds the flexible shaft 4 in the axial direction of the flexible shaft 4, thereby moving the cutting head 2 inserted into the pipe (branch pipe 9) at a constant speed along the pipe axis of the pipe (branch pipe 9).

Conventionally, as an inner pipe cutting device for cutting the inner circumferential surface 92 of a pipe (branch pipe 9), for example, the inner pipe cutting device disclosed in Patent Document 1 is known. However, this device requires a boring bar with a length corresponding to the distance to insert the cutting head into the pipe, so if the boring bar is long, there is a problem that the inner pipe cutting device cannot be brought into the limited space of the drilling hole 13, or even if it can be brought in, it becomes difficult to insert the cutting head into the pipe (branch pipe 9). Furthermore, since a supply of hydraulic oil is required to bring the cutting blade into contact with the inner pipe surface, a separate device for supplying hydraulic oil is required, making it difficult to use in the limited space of the drilling hole 13.

In this regard, according to the pipe cutting method described in any one of (2) to (5) or the pipe inner surface cutting device 1 described in any one of (6) to (9), the cutting head 2 is rotated by the rotational force of the rotating device (electric screwdriver 3) used outside the pipe (branch pipe 9) transmitted by the flexible shaft (flexible shaft 4). Therefore, for example, by winding up the flexible shaft (flexible shaft 4), the pipe inner surface cutting device 1 can be easily carried into the limited space of the drilling hole 13. Then, when inserting the cutting head 2 into the pipe (branch pipe 9), the flexible shaft (flexible shaft 4) in the wound state can be fed out as it is inserted. Therefore, even in the limited space of the drilling hole 13, the work of inserting the cutting head 2 into the pipe (branch pipe 9) is easy. Furthermore, the biasing means 26 provided on the cutting head 2 biases the cutting blades 22, 23 outward in the direction of the rotation radius of the cutting head 2, and presses them against the inner surface 92 of the pipe (branch pipe 9) from a direction perpendicular to the pipe axis of the pipe (branch pipe 9), so no separate device is required to bring the cutting blades 22, 23 into contact with the inner surface 92 of the pipe (branch pipe 9). Therefore, the pipe inner surface cutting device 1 can be easily used in the limited space of the drilling hole 13.

The above embodiment is merely an example and does not limit the present invention in any way. Naturally, the present invention can be improved and modified in various ways without departing from the spirit of the invention. For example, the pipe cutting method and pipe inner surface cutting device in the above embodiment are described using a pipe for supplying gas as an example, but are not limited to this and can also be applied to a pipe for supplying drinking water.

1 Tube inner surface cutting device 2 Cutting head 3 Electric screwdriver (an example of a rotating device)
4 Flexible shaft (an example of a flexible shaft)
8 Main pipe 9 Branch pipe (example of pipe)
13 drilling hole 14 squeeze tool 15 elastic seal member 16 plug member 17 pipe inner surface cutter 22 cutting blade 23 cutting blade 26 biasing means 91 cutting opening 92 inner peripheral surface A11 rotating shaft

Claims (9)

A pipe cutting method for cutting an existing pipe made of a thermoplastic resin extending from a main pipe in order to remove the pipe, comprising:
drilling a borehole at the location where the pipe is buried to expose the pipe;
closing the exposed tube with a squeeze tool and making a first cut in the tube downstream of the squeeze tool;
removing the squeeze tool from the tube;
an elastic seal member is inserted into the tube from the cut opening formed by the first cut to a predetermined position in the tube, thereby temporarily closing the tube;
a pipe inner surface cutting device for cutting an inner circumferential surface of the pipe is inserted from the cut opening, and the pipe inner surface cutting device cuts a portion of the inner circumferential surface downstream of the elastic seal member while moving from the position where the pipe inner surface cutting device was inserted toward the cut opening , thereby removing impurities adhering to the inner circumferential surface;
After removing the tube inner surface cutting device from the cut opening, a plug member made of a thermoplastic resin is inserted into the tube from the cut opening, and the plug member is fused to the portion of the inner circumferential surface that has been cut by the tube inner surface cutting device, thereby blocking the tube;
inserting a tube inner surface cutter into the tube from the cutting opening, and performing a second cut of the tube with the tube inner surface cutter downstream of a position where the plug member is fused;
A pipe cutting method comprising the steps of: A pipe cutting method for cutting an existing pipe made of a thermoplastic resin extending from a main pipe in order to remove the pipe, comprising:
drilling a borehole at the location where the pipe is buried to expose the pipe;
closing the exposed tube with a squeeze tool and making a first cut in the tube downstream of the squeeze tool;
removing the squeeze tool from the tube;
an elastic seal member is inserted into the tube from the cut opening formed by the first cut to a predetermined position in the tube, thereby temporarily closing the tube;
A pipe inner surface cutting device that cuts an inner circumferential surface of the pipe is inserted from the cutting opening, and the pipe inner surface cutting device cuts a downstream side of the elastic seal member of the inner circumferential surface;
a plug member made of a thermoplastic resin is inserted into the pipe from the cut opening, and the plug member is fused to the portion of the inner circumferential surface that has been cut by the pipe inner surface cutting device, thereby closing the pipe;
inserting a tube inner surface cutter into the tube from the cutting opening, and performing a second cut of the tube with the tube inner surface cutter downstream of a position where the plug member is fused;
The pipe inner surface cutting device is
a cutting head insertable into the tube;
a rotating device used outside the tube;
a flexible shaft that transmits a rotational force of the rotating device to the cutting head and rotates the cutting head;
To have
The cutting head includes:
A pair of cutting blades positioned symmetrically with respect to a rotation axis of the cutting head;
a biasing means for biasing each of the pair of cutting blades outward in a radial direction of the cutting head and pressing the pair of cutting blades against the inner circumferential surface in a direction perpendicular to the axis of the pipe;
To have
A pipe cutting method comprising the steps of: The tube cutting method according to claim 2,
the biasing means generates a biasing force in a direction parallel to the rotation axis;
At least one of the biasing means and the pair of cutting blades has a deflection portion formed of an inclined surface that obliquely intersects with the direction of the rotation axis and the direction of the rotation radius;
The biasing force is converted into a force in the radial direction of the rotation through the conversion portion and transmitted to the pair of cutting blades;
A pipe cutting method comprising the steps of: The pipe cutting method according to claim 2 or 3,
The cutting head cuts the inner circumferential surface while moving along the tube axis;
the cutting head has an outer periphery on a front side in the direction of movement of the cutting blades covered with a cylindrical positioning roller;
the positioning roller is rotatably fixed to the cutting head coaxially with the rotation shaft;
A pipe cutting method comprising the steps of: 5. The pipe cutting method according to claim 2,
a feed device disposed between the rotating device and the pipe, the feed device feeds the flexible shaft in an axial direction of the flexible shaft to move the cutting head inserted into the pipe at a constant speed along the pipe axis of the pipe;
A pipe cutting method comprising the steps of: A pipe inner surface cutting device for cutting an existing pipe made of thermoplastic resin extending from a main pipe, inserting the pipe through a cut opening formed by cutting the pipe in a drilling hole, and cutting the inner peripheral surface of the pipe to form a surface for welding a plug member made of thermoplastic resin , comprising:
a cutting head insertable into the tube;
a rotating device used outside the tube;
a flexible shaft that transmits a rotational force of the rotating device to the cutting head and rotates the cutting head;
To have
The cutting head includes:
A pair of cutting blades positioned symmetrically with respect to a rotation axis of the cutting head;
a biasing means for biasing each of the pair of cutting blades outward in a radial direction of the cutting head and pressing the pair of cutting blades against the inner circumferential surface in a direction perpendicular to the axis of the pipe;
To have
A pipe inner surface cutting device characterized by the above. 7. The pipe inner surface cutting device according to claim 6,
the biasing means generates a biasing force in a direction parallel to the rotation axis;
At least one of the biasing means and the pair of cutting blades has a deflection portion formed of an inclined surface that obliquely intersects with the direction of the rotation axis and the direction of the rotation radius;
The biasing force is converted into a force in the radial direction of the rotation through the conversion portion and transmitted to the pair of cutting blades;
A pipe inner surface cutting device characterized by the above. 8. The pipe inner surface cutting device according to claim 6,
The cutting head cuts the inner circumferential surface while moving along the tube axis;
the cutting head has an outer periphery on a front side in the direction of movement of the cutting blades covered with a cylindrical positioning roller;
the positioning roller is rotatably fixed to the cutting head coaxially with the rotation shaft;
A pipe inner surface cutting device characterized by the above. 9. The pipe inner surface cutting device according to claim 6,
a feed device disposed between the rotating device and the pipe, the feed device feeds the flexible shaft in an axial direction of the flexible shaft to move the cutting head inserted into the pipe at a constant speed along the pipe axis of the pipe;
A pipe inner surface cutting device characterized by the above.

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