Pipe cutting device and pipe cutting method

Abstract

To provide a pipe cutting device capable of efficiently cutting a pipe from the inside, even when the pipe is made of a hard material, by strongly pressing a rotary blade against a part to be cut, without scattering dust to the surroundings.SOLUTION: A pipe cutting device is inserted into a pipe from one end of the pipe to cut the pipe from the inside, and includes: a shaft; a circular rotary blade fixed to one end of the shaft, and having a diameter smaller than the inner diameter of the pipe; an opening disc which is provided at a predetermined distance from the rotary blade, in which the shaft is inserted into an opening provided at its center and which has an outer diameter that covers one end of the pipe; fixing means for fixing the opening disc to one end of the pipe; a bearing that covers the opening and rotatably and swingably supports the shaft; a stopper for fixing the position of a rotary disc relative to the shaft; and a connection end for transmitting rotational driving force applied from a rotary drive device to the shaft at the other end of the shaft.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pipe cutting device for cutting a pipe from its inner surface, and a pipe cutting method using the same. [Background technology]

[0002] In high-rise buildings such as apartment complexes, wastewater from facilities such as bathrooms, sinks, washrooms, and toilets is discharged via horizontal branch pipes that lead to the drains in the rooms where each facility is located, and then through a shared drainage standpipe that runs through each floor and into a sewage tank or other facility.

[0003] Bathroom drains in apartment buildings and other buildings are often equipped with drain traps known as bowl traps or belt traps. Specifically, as shown in FIG. 11 , bowl trap (drain trap) 20 has an inner cylindrical portion 21b extending upright from bottom portion 21a. It includes a cylindrical trap body 21 with an open top and a bottomed opening, and a bowl-shaped body 22 fitted over inner cylindrical portion 21b. It also has a connecting thread portion 21c extending downward from inner cylindrical portion 21b. A drain strainer 23 is disposed in the open drain outlet of bowl trap 20. Bowl trap 20 is connected to a horizontal drain pipe 25 embedded in the slab via connecting thread portion 21c, and drains water into a sewer pipe via a drain standpipe (not shown) that connects to horizontal drain pipe 25.

[0004] If such drain traps are made of metal such as cast iron, they may deteriorate over time and develop rust after several decades of use, causing breaks and leaks. To stop such leaks, methods of repairing drain traps are known.

[0005] For example, Patent Document 1 below provides a bathroom drain repair method that allows for the work of restoring the function of the outflow flow path around the drain trap body and the work of connecting the unit drain pipe to the outflow flow path when the bathroom is unitized to be performed as commonly as possible. Patent Document 1 also discloses a repair method in which, after removing the inner cylindrical portion of the drain trap that has deteriorated over time, an inner polyvinyl chloride pipe is inserted into the cylindrical portion that remains in the area where the inner cylindrical portion was removed, and a waterproofing agent is filled in the gap between the cylindrical portion and the inner pipe, thereby restoring the drain inlet to replace the removed inner cylindrical portion.

[0006] Patent Document 1 discloses methods for removing the inner tube, such as using a hole saw to cut the inner tube from above, or cutting off the outer half of the inner tube and then breaking up the remaining part with a steel rod or the like and smoothing it with a diamond drilling blade, or making multiple vertical cuts in the inner tube with a saber saw or the like and breaking off each cut piece.

[0007] However, methods such as those disclosed in Patent Document 1, in which the inner cylinder is ground from above or the outer half is ground and then the remaining portion is broken with a steel rod or the like, generate a large amount of dust during grinding and take a long time to complete, making them inefficient methods. Furthermore, the method of making multiple vertical cuts with a saber saw is difficult for hard materials such as cast iron and is not practical.

[0008] Meanwhile, pipe cutters have been proposed that cut polyvinyl chloride pipes or the like from the inside by running a circular rotary blade along the inside of the pipe. For example, Patent Document 2 listed below proposes a pipe cutter that has a fitting seat that is inserted into the inside of the pipe to be cut and has a means for pressing against the circumferential wall of the pipe to fix this inserted state, the base end of a cutter shaft that has an appropriate engagement portion at its tip with a rotating jig is supported on this fitting seat so as to be able to rotate and swing freely, and the cutter shaft is provided with a cutting disk whose diameter is smaller than the inside diameter of the pipe.

[0009] Furthermore, the following Patent Document 3 discloses a pipe cutter consisting of a rotating shaft with a shank portion at one end and a cutter blade provided to protrude circumferentially from the other end of the rotating shaft, in which a cutting depth setting flange is provided around the rotating shaft at a predetermined distance from the cutter blade toward the shank portion, which allows the cutter to trace the edge of the pipe.

[0010] The pipe cutter described in Patent Document 2 has a fitting seat provided with a means for pressing the pipe cutter against the circumferential wall of the pipe to fix the inserted state, further forward than the cutting edge, making it difficult to cut deep parts such as near the base of the inner cylindrical part of a drain trap. Also, with this type of pipe cutter, the fitting seat is made of an elastic material such as rubber, making it difficult to press the rotary blade against the part to be cut with a strong force, and even if it is possible to cut polyvinyl chloride pipes, it would be difficult to cut hard materials such as drain traps made of hard cast iron.

[0011] Furthermore, even with the pipe cutter described in Patent Document 3, the cutting depth setting flange is brought into sliding contact with the edge of the pipe while the rotary blade is pressed against the part to be cut, making it difficult to press the rotary blade against the part to be cut with sufficient force. While it is possible to cut polyvinyl chloride pipes, etc., it would be difficult to cut a hard cast iron drain trap. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 2023-64400 [Patent Document 2] Japanese Patent Application Publication No. 4-300118 [Patent Document 3] Japanese Patent Application Publication No. 7-164238 Summary of the Invention [Problem to be solved by the invention]

[0013] In order to solve the problems described above, the present invention aims to provide a pipe cutting device that can efficiently cut pipes made of hard materials from the inside without scattering dust around by pressing a rotary blade against the part to be cut with great force. [Means for solving the problem]

[0014] One aspect of the present invention is a pipe cutting device that is inserted into one end of a pipe to cut the pipe from the inside, the pipe cutting device comprising: a shaft; a circular rotary blade fixed to one end of the shaft and having a diameter smaller than the inner diameter of the pipe; an aperture plate having an outer diameter that covers one end of the pipe and through which the shaft is inserted at a predetermined distance from the rotary blade and has an opening provided in the center; a fixing means for fixing the aperture plate to the one end of the pipe; a bearing that rotatably and oscillatably supports the shaft and is fixed to cover the opening; a stopper that fixes the position of the bearing relative to the shaft; and a connecting end for transmitting a rotational driving force applied from a rotary drive device to the shaft at the other end of the shaft. With this pipe cutting device, the aperture plate, to which the bearing that rotatably and oscillatably supports the shaft is fixed, is fixed to one end of the pipe by the fixing means, so that by tilting the rotary drive device, an operator can rotate the rotary blade fixed to the tip of the shaft in a circumferential direction, with the bearing as a fulcrum for the shaft. This allows the rotary blade to trace the inner surface of the pipe at a constant height, and at that time, using the bearing as a fulcrum, the rotary blade can be pressed with great force against the part of the inner surface of the pipe to be cut using the principle of leverage. Also, because the platen to which the bearing is fixed has an outer diameter that covers one end of the pipe, the platen covers one end of the pipe when cutting, so that dust generated during cutting can be contained inside the pipe.

[0015] In addition, it is preferable that the distance between the position where the shaft is supported and the position where the circular rotary blade is fixed in the cutting device is 50 to 300 mm, as this allows the rotary blade to be pressed against the part to be cut with greater force without significantly bending the shaft.

[0016] Furthermore, it is preferable that the cutting device has an extension shaft with a universal joint connected to the connecting end, and the rotational drive force is transmitted to the shaft via the extension shaft. When obstacles such as a bathtub or wall are present around the pipe to be cut, there may be insufficient space for the operator to tilt the rotary drive device and move it circumferentially. In such cases, by connecting an extension shaft with a universal joint to the connecting end of the tip of the shaft, even if there is insufficient space to tilt the rotary drive device due to interference with the obstacle, the shaft can be tilted sufficiently by bending the extension shaft. In other words, the angle at which the operator must tilt the rotary drive device to tilt the shaft sufficiently can be reduced.

[0017] In addition, the cutting device has a water supply passage that passes through the opening plate, which allows water to be applied from the outside to the rotary blade that cuts the pipe, thereby cooling the rotary blade and extending the service life of the rotary blade before it becomes worn and difficult to use.

[0018] Another aspect of the present invention is a method for cutting a pipe using the above-described pipe cutting device, comprising the steps of connecting a rotary drive unit for transmitting a rotational drive force to the connecting end, adjusting the position of a stopper so that the circular rotary blade abuts a predetermined position on the pipe, inserting the rotary blade into the inside of the pipe from the upper end and fixing an aperture plate to the upper end of the pipe with a fixing means so as to cover the upper end of the pipe, and pressing the rotary blade fixed to the shaft against the inner surface of the pipe while rotating it with the rotational drive force and moving the circular rotary blade circumferentially to cut the pipe. According to this pipe cutting method, by pressing the rotary blade against the portion to be cut with a strong force, even pipes made of hard materials can be efficiently cut from the inside without scattering a large amount of dust. Specifically, even hard pipes such as the inner tube of a cast iron bowl trap can be efficiently cut without scattering a large amount of dust. Furthermore, if the opening plate has a water supply passage that passes through it, water can be supplied through the water supply passage and applied to the circular rotary blade to cool it, thereby extending the service life of the rotary blade before it becomes worn and difficult to use. [Effects of the Invention]

[0019] According to the present invention, the rotary blade can be pressed against the part to be cut with a strong force, so that even a pipe made of a hard material such as cast iron can be cut from the inside without scattering a large amount of dust around. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic side view of a tube cutting device 10 connected to a rotary drive device 50 according to an embodiment. [Figure 2] FIG. 2 is a partial cross-sectional schematic view of a tube cutting device 10 connected to a rotary drive device 50 according to an embodiment. [Figure 3] FIG. 3 is a schematic diagram of the vicinity of the rotary blade 2 as viewed from the tip side. [Figure 4] FIG. 4 is a schematic diagram of the vicinity of the aperture platen 3 as viewed from the tip side. [Figure 5] FIG. 5 is a process diagram illustrating a method for cutting the inner cylindrical portion 21b of the cast iron bowl trap of the embodiment. [Figure 6] FIG. 6 is a process diagram illustrating a method for cutting the inner cylindrical portion 21b of the cast iron bowl trap of the embodiment. [Figure 7] FIG. 7 is a process diagram illustrating a method for cutting the inner cylindrical portion 21b of the cast iron bowl trap of the embodiment. [Figure 8] FIG. 8 is an explanatory diagram illustrating a state in which a bathtub 60 is close when cutting the inner cylindrical portion 21b of the cast iron bowl trap of the embodiment. [Figure 9] FIG. 9 is an explanatory diagram illustrating the state when an extension shaft 11 having a universal joint 11b is connected to a shaft 1 when a bathtub 60 is nearby when cutting the inner cylindrical portion 21b of a cast iron bowl trap of the embodiment. [Figure 10] FIG. 10 is a partial cross-sectional schematic view of a pipe cutting device 110 provided with a water supply channel 30 and connected to a rotary drive device 50 according to an embodiment. [Figure 11] FIG. 11 is a partial schematic cross-sectional view for explaining the cross-sectional structure of bowl trap 20. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pipe cutting device and a pipe cutting method using the same according to the present invention will be described in detail below with reference to the drawings.

[0022] FIG. 1 is a schematic side view of a tube cutting device (hereinafter also simply referred to as a cutting device) 10 according to this embodiment, and FIG. 2 is a schematic partial cross-sectional view of the cutting device 10. FIGS. 1 and 2 show the cutting device 10 connected to a rotary drive device 50. In this embodiment, the rotary drive device 50 is an electric screwdriver. In the following description, the lower side of the paper may be referred to as the leading end side, and the upper side of the paper may be referred to as the trailing end side.

[0023] In Figures 1 and 2, 1 is a shaft, 2 is a circular rotary blade with a diameter smaller than the inner diameter of the pipe, 3 is an aperture plate having an opening 3a through which the shaft is inserted, 4 is a fixing means (fixing jig) for fixing the aperture plate 3 to one end of the pipe, 5 is a bearing that covers the opening 3a and supports the shaft 1 so that it can rotate and swing freely, 6 is a connection end (also called a shank portion) that transmits the rotational driving force applied from the rotary drive device 50 to the shaft 1, 7 is a self-lubricating O-ring that reduces friction between the shaft 1 and the bearing 5, and 8 is a stopper that is fixed to the shaft 1 to adjust the position of the aperture plate 3.

[0024] 3 is a schematic diagram of the vicinity of the rotary blade as viewed from the tip side, and FIG. 4 is a schematic diagram of the vicinity of the aperture platen 3 as viewed from the tip side.

[0025] 1 and 3, a circular rotary blade 2 is fixed to the tip of a shaft 1 by a bolt and nut 2a. Also, referring to Fig. 1 and 4, the shaft 1 is inserted into an opening 3a of a circular aperture plate 3 having an opening 3a in the center. The shaft 1 is made of metal, preferably hard steel.

[0026] 2 and 4, a bearing 5 is fixed to the platen 3 to support the shaft 1 so that it can rotate and swing freely.

[0027] The platen 3 is a member that supports the bearing 5 and has an outer diameter sufficient to cap one end of the pipe to be cut. The bearing 5 is fixed to the platen 3 so that the axis of the shaft 1 that it supports coincides with the center of the opening 3a. In this embodiment, the bearing 5 is fixed by welding to the upper surface of the platen 3. There are no particular limitations on the method for fixing the bearing to the platen, and examples include bolting the bearing to the upper surface of the platen via a flange, or fitting the bearing into the opening of the platen and welding it to the opening.

[0028] The bearing 5 has a mechanism for supporting the shaft 1 so that it can rotate and swing freely. Such a bearing is usually also called an aligning bearing. In this embodiment, referring to Figures 2 and 4, the bearing 5 includes an inner ring 5a through which the shaft 1 is inserted to support it, rolling elements 5b, an outer ring 5c ​​provided on the outside of the rolling elements 5b, and a housing 5d that supports the outer ring 5c. The outer peripheral surface of the outer ring 5c ​​is a convex spherical surface, and the inner peripheral surface of the housing 5d is a concave spherical surface.

[0029] The inner ring 5a fixes the shaft 1, and the rolling elements 5b roll, thereby rotatably supporting the shaft 1 relative to the outer ring 5c. The convex spherical outer surface of the outer ring 5c ​​slides against the concave spherical inner surface of the housing 5d, thereby allowing the housing 5d to support the outer ring 5c ​​in a swingable manner. Any conventional bearing having a mechanism for rotatably and swingably supporting a shaft can be used without any particular limitation, as long as it has a mechanism for rotatably and swingably supporting the shaft.

[0030] 2 and 4, fixing means 4 for fixing the aperture plate 3 to one end of the pipe is provided on the back surface of the aperture plate 3, which is the surface facing the tip side. In this embodiment, the fixing means 4 is a fixing jig including two arc-shaped pressing members 4a and 4b arranged in an arc shape slightly inside the outer periphery of the aperture plate 3, bolts 4c and 4d for pushing and spreading the pressing members 4a and 4b toward the outer periphery of the aperture plate 3, and guide pins 4e, 4f, 4g, and 4h for guiding the spreading direction of the pressing members 4a and 4b when they are pushed toward the outer periphery and for fixing the spread pressing members 4a and 4b.

[0031] 4, in the fixing means 4, the bolts 4c and 4d are fitted into threaded holes that penetrate the platen 3, and their tip portions are housed in recesses r1 and r2 that are provided in the holding members 4a and 4b after passing through the platen 3. When the bolts 4c and 4d that are fitted into the threaded holes provided in the platen 3 are tightened and advanced, the wall surfaces of the recesses r1 and r2 that are provided in the holding members 4a and 4b are pressed against the shafts of the bolts 4c and 4d, and the holding members 4a and 4b are each pushed outward from the platen 3. Guide pins 4e, 4f, 4g, and 4h are housed in recesses r3, r4, r5, and r6, respectively, and as each of pressing members 4a and 4b is pushed outward from platen 3, guide pins 4e, 4f, 4g, and 4h come into pressure contact with the wall surfaces of recesses r3, r4, r5, and r6, respectively, and fix each of the pushed-out pressing members 4a and 4b. In this way, by pushing out each of pressing members 4a and 4b from the inner surface of the end of the tube, pressing members 4a and 4b come into pressure contact with the inner surface of the tube, and platen 3 is fixed at the end surface of the tube so as to cover the end of the tube.

[0032] The form of the fixing means is not limited to this form, and for example, the clamping member can be omitted and multiple bolts fitted into threaded holes provided in the opening plate can be tightened so that the tips of the bolts press against the inner surface of the end of the pipe to fix the opening plate, or the joint can be fixed from the outside of the opening plate with a belt, adapter or tape, etc., so long as the opening plate can be fixed so as to cover the end of the pipe like a lid.

[0033] 1 and 2, the cutting device 10 includes a stopper 8 fixed to the shaft 1 to adjust the position of the aperture platen 3. The stopper 8 is a member that is fixed to the shaft 1 by inserting the shaft 1 through it, tightening a screw 8a onto the shaft 1, and pressing the tip of the screw 8a against the surface of the shaft 1.

[0034] The stopper 8 is disposed rearward of the platen 3 and is fixed to the shaft 1. The stopper 8 presses the upper end of the bearing 5, thereby adjusting the distance from the position where the bearing 5 supports the shaft 1 to the rotary blade 2. Specifically, the stopper 8 is disposed at a position corresponding to the desired distance, and at that position, a screw 8a fitted into a threaded hole in the stopper 8 is tightened, whereby the tip of the screw 8a is pressed against the surface of the shaft 1, and the stopper 8 is fixed at that position. The form of the stopper is also not particularly limited as long as it allows the position of the bearing or platen to be adjusted.

[0035] The distance from the position where the shaft 1 is supported to the position where the circular rotary blade 2 is fixed, which is adjusted by the stopper 8, can be adjusted as appropriate, but for example, when cutting the inner cylindrical part of a cast iron bowl trap, it is preferable to set it to 50 to 300 mm, even 50 to 200 mm, and especially 50 to 100 mm, because this allows the rotary blade to be pressed against the part to be cut with greater force without significantly bending the shaft.

[0036] In addition, in the cutting device 10, in order to prevent wear due to friction between the bearing 5 and the stopper 8, it is preferable that a self-lubricating O-ring made of polytetrafluoroethylene (PTFE), polyacetal (POM), or the like is inserted between the bearing 5 and the stopper 8.

[0037] A circular, flat rotary blade 2 is fixed to the tip of the shaft 1. Referring to Figures 2 and 3, the rotary blade 2 is fixed by a bolt and nut 2a that screws into a thread (not shown) engraved on the tip of the shaft 1.

[0038] The rotary blade is a circular blade with a diameter smaller than the inner diameter of the pipe to be cut. It cuts the pipe by applying the blade's peripheral surface to the pipe. For example, when cutting hard materials such as the inner cylinder of a cast iron bowl trap, a rotary blade with a cutting edge made of abrasive grains, such as diamond grains, attached to the outer periphery of a hard metal disk or a circular cutting wheel is preferably used. For soft materials such as polyvinyl chloride pipes, a rotary blade with a saw blade attached to the outer periphery of a metal disk is preferably used.

[0039] The diameter of the rotary blade is smaller than the inner diameter of the pipe to be cut, and is selected so that the blade will penetrate the thickness of the pipe at a predetermined position when the shaft is tilted and swung, as described below. For example, when cutting the inner cylindrical part of a cast iron bowl trap, it is preferable to select a rotary blade with a diameter of 30 to 80 mm, or even 40 to 60 mm.

[0040] The shaft 1 has a connecting end 6 at its rear end for connecting to the rotation drive device 50. The connecting end 6 is a portion for connecting the rotation drive device 50, and is a portion for directly or indirectly fixing the shaft 1 to the rotation drive device 50 and transmitting the rotational drive force applied from the rotation drive device 50 to the shaft 1. The connecting end 6 may be a round shaft (straight shank) fixed in the chuck of a typical electric screwdriver, or may have a joint structure in which a socket (square, hexagonal, dodecagonal, etc.) is attached to the tip of a short shaft connected to the chuck, and a bolt or nut that fits into the socket is connected to the tip of the shaft 1.

[0041] The shaft 1 is connected to a rotary drive device 50 through the connecting end 6. The rotary drive device 50 is a device that applies a rotational driving force to the shaft 1 and is preferably a device that can be held by an operator to tilt the shaft 1. In this embodiment, referring to FIG. 1 , an electric screwdriver is shown that includes a trigger switch 50a that an operator presses with their finger to rotate a motor (not shown) of the rotary drive device 50, a grip 50b that the operator holds, and a chuck 50c that directly or indirectly secures the connecting end 6 of the shaft 1. When the trigger switch 50a is pressed to turn ON, the rotary drive device 50 applies a rotational driving force to the shaft 1, rotating the rotary blade 2 fixed to the tip of the shaft 1.

[0042] The cutting device 10 of this embodiment has been described in detail above. Next, as one embodiment of a method for cutting a pipe using the cutting device 10, a method for cutting the inner cylindrical portion of a cast iron bowl trap (hereinafter also simply referred to as a cutting method) will be described in detail with reference to Figs. 5 to 7.

[0043] In the cutting method of this embodiment, the trap body 21 of the cast iron bowl trap to be cut is prepared as shown in Figure 5. Also, as described above, the rotation drive device 50 is connected to the cutting device 10 and fixed to the inner cylindrical portion 21b of the trap body 21.

[0044] 5, when the shaft 1 is tilted, the distance between the position where the bearing 5 supports the shaft 1 and the position where the rotary blade 2 is fixed is adjusted so that the rotary blade 2 hits the intended predetermined cutting position A on the inner cylindrical portion 21b of the trap body 21. This distance adjustment is performed by adjusting the position where the stopper 8 is fixed, as described above.

[0045] After fixing the stopper 8 so that the rotary blade 2 contacts the cutting position A, the operator inserts the rotary blade 2 fixed to the tip of the cutting device 10 into the inner cylindrical portion 21b to be cut from the upper end. Then, the fixing means 4 fixes the aperture plate 3 to the upper end of the inner cylindrical portion 21b. Specifically, the aperture plate 3 is set so that it covers the upper end of the inner cylindrical portion 21b, and then the bolts 4c and 4d of the fixing means 4, which are fitted into the threaded holes that penetrate the aperture plate 3, are tightened. By tightening the bolts 4c and 4d, the pressing members 4a and 4b are pushed apart by the inner surface of the inner cylindrical portion 21b, and the pressing members 4a and 4b are pressed against the inner surface of the inner cylindrical portion 21b, thereby fixing the aperture plate 3. In this manner, the cutting device 10 is set to the inner cylindrical portion 21b, as shown in FIG. 5 .

[0046] 6, the operator grasps the grip 50b of the rotary drive device 50 connected to the cutting device 10 and pulls the trigger switch 50a of the rotary drive device 50, which drives the motor (not shown) of the rotary drive device 50 to rotate the shaft 1. The rotation of the shaft 1 rotates the rotary blade 2 fixed to the tip of the shaft 1. The operator then turns on the trigger switch 50a of the rotary drive device 50 to rotate the shaft 1, while pressing the rotary blade 2 against the inner cylindrical portion 21b at the height of the predetermined cutting position A.

[0047] After a portion of the inner cylindrical portion 21b at the cutting position A is cut, the rotary drive device 50 is tilted and moved in a circumferential direction along the inner wall of the inner cylindrical portion 21b, thereby pressing the rotary blade 2 against other portions of the inner cylindrical portion 21b at the height of the predetermined cutting position A. In this manner, the entire inner cylindrical portion 21b is cut by sequentially moving the rotary blade 2 in a circumferential direction horizontally at the height of the predetermined cutting position A. The bearing 5 supporting the shaft 1 of the cutting device 10 is pivotable relative to the shaft 1, allowing the rotary blade 2 fixed to the tip of the shaft 1 to pivot freely in the circumferential direction. When cutting the inner cylindrical portion 21b, the bearing 5 provided in the cutting device 10 serves as a fulcrum, allowing the rotary blade 2 to be pressed against the inner surface of the inner cylindrical portion 21b with a strong force. Therefore, even if the inner cylindrical portion 21b is made of a hard material such as cast iron, efficient cutting can be achieved in a relatively short time.

[0048] Furthermore, during the cutting operation, the opening at the end of the inner tube portion 21b is sealed by the opening plate 3, so that the cutting chips generated when cutting the inner tube portion 21b are confined inside the inner tube portion 21b and do not scatter outside the inner tube portion 21b.

[0049] In this way, the inner cylindrical portion 21b can be cut and removed from the trap body 21, as shown in FIG.

[0050] In the above-described cutting method, if there are obstacles such as walls or a bathtub around the pipe to be cut, the worker may not be able to secure enough space to tilt or move the rotary drive unit 50. Specifically, for example, as shown in Fig. 8, if the trap body 21 of the bowl trap is positioned adjacent to the bathtub 60, when the worker tilts the rotary drive unit 50 and moves it circumferentially along the inner wall of the inner cylindrical portion 21b, the bathtub 60 may interfere, making it difficult for the rotary blade 2 to bite into the inner cylindrical portion 21b sufficiently.

[0051] In such a case, by connecting an extension shaft having a universal joint capable of transmitting the rotational driving force of the rotational driving device 50 to the connection end 6 of the shaft 1, the angle at which the worker must tilt the rotational driving device 50 in order to bring the rotary blade 2 into contact with the inner cylindrical portion 21b of the shaft 1 can be reduced.

[0052] Referring to Figure 9, an extension shaft 11 having a universal joint 11b is connected to the connecting end 6 of the shaft 1. A universal joint is a joint that allows the angle at which two members are joined to be freely changed. The swivel angle (angle of the range of motion) of the universal joint is not particularly limited, but is preferably, for example, 5 to 60 degrees, and more preferably, 10 to 45 degrees. The length of the extension shaft is also not particularly limited, but is preferably about 200 to 1000 mm, and more preferably, about 300 to 600 mm.

[0053] The extension shaft 11 comprises an extension shaft body 11a, a universal joint 11b fixed to the tip end of the extension shaft body 11a, and a cover 11c through which the extension shaft body 11a is inserted and supported. The universal joint 11b is fixed to the tip end of the extension shaft body 11a and has a socket 11d at the tip end. The socket 11d is fitted with and connected to a bolt or nut 6a attached to the connecting end 6 of the shaft 1. The cover 11c is a tubular member through which the extension shaft body 11a is inserted, and is equipped with bearings 11e and 11f that rotatably support the extension shaft body 11a. The cover 11c is a safety feature that prevents the rotating extension shaft body 11a from being exposed.

[0054] 9, by connecting an extension shaft 11 having a universal joint 11b to the connection end 6 of the shaft 1, it is possible to reduce the angle at which the operator must tilt the rotation drive unit 50 in order to sufficiently tilt the shaft 1. Furthermore, because the rotational drive force is transmitted to the shaft 1 via the extension shaft 11, even if sufficient space cannot be secured for tilting the rotation drive unit 50, the entire surface of the inner cylindrical portion 21b can be cut by sequentially moving the rotary blade 2 horizontally at the height of the predetermined cutting position A in a circumferential direction.

[0055] According to the cutting method described above, the cutting device 10 can use the rotating and pivoting rotary blade 2 to efficiently cut the inner cylindrical portion 21b in the horizontal direction at the predetermined cutting position A. Furthermore, the opening plate covers the inner cylindrical portion 21b, so that dust generated during cutting can be prevented from flying up to the work area during the cutting operation.

[0056] The above is a detailed description of an embodiment of the pipe cutting device and pipe cutting method according to the present invention. The pipe cutting device and pipe cutting method according to the present invention are not limited to the above embodiment, and may be appropriately modified within the scope of the present invention. For example, the following modifications can be made.

[0057] When the above-described pipe cutting device 10 is used to cut hard pipes such as the inner cylinder of a cast iron bowl trap, the circular rotary blade 2 cuts hard cast iron, and frictional heat generated during cutting can wear down the blade, making it difficult to use in a relatively short period of time. In such cases, by applying water to the rotary blade 2 to cool it while cutting the pipe, the circular rotary blade 2 is less likely to deteriorate due to frictional heat during cutting, and the service life of the rotary blade 2 can be improved. A cutting device 110 according to another embodiment, which can cut pipes while applying water to the rotary blade 2 to cool it, will be described with reference to FIG. 10.

[0058] 10 is a partial cross-sectional schematic diagram of a cutting device 110 connected to a rotary drive device 50. The cutting device 110 has the same configuration and function as the cutting device 10, except that it uses an open platen 13 having a water supply channel 30 passing through the open platen. In the cutting device 110 shown in FIG. 10, a through hole H is formed in the open platen 13, and a thread is cut in the through hole H for connecting a male thread hose joint (commonly known as a bamboo shoot).

[0059] Male threaded hose fittings 33 and 34 are connected to the threads of through-hole H, with short hose 32 connected to male threaded hose fitting 34 and water supply hose 31 connected to male threaded hose fitting 33. Water supply hose 31 is connected to a water supply means such as a water main or water supply pump (not shown). In addition, short hose 32 guides the water supplied from water supply hose 31 so that it hits rotary blade 2. These form water supply channel 30 for hitting water against the circular rotary blade.

[0060] In carrying out the pipe cutting method, such a cutting device 110 is employed, and while rotating the rotary blade 2 to cut the pipe, water supplied through the water supply passage 30 is directed at the rotary blade 2 to cool it. This makes the circular rotary blade 2 less susceptible to deterioration due to frictional heat during cutting, and improves the service life of the rotary blade 2. [Explanation of symbols]

[0061] 1 shaft 2 rotary blades 2a Bolts and nuts 3 Aperture plate 3a aperture 4 Fixing means 4a, 4b Holding member 4c, 4d bolts 4e, 4f, 4g, 4h guide pins 5. Bearings 5a Inner circle 5b Rolling element 5c outer ring 5d housing 6 Connection end 6a Bolt or nut 8 Stopper 8a Screw 10,110 Cutting equipment 11 Extension shaft 11b Universal joint 20 Bowl trap (drain trap) 21 Trap body 21a bottom 21b Inner cylinder part 21c Connection screw part 22 Bowl-shaped body 23 Drainage strainer 25 Drain pipe 30 Water supply channel 31 Water supply hose 32 Short hose 33, 34 Male thread hose joint 50 Rotational drive unit 50a trigger switch 50b grip 50c zipper 60 Bathtub A Cutting position

Claims

1. A pipe cutting device that is inserted into a pipe from one end thereof to cut the pipe from the inside, A shaft and a circular rotary blade fixed to one end of the shaft and having a diameter smaller than the inner diameter of the pipe; an aperture plate having an outer diameter for capping one end of the tube, the aperture being provided in the center of the aperture and spaced a predetermined distance from the rotary blade, and the shaft being inserted through the aperture; a fixing means for fixing the aperture plate to one end of the tube; a bearing that supports the shaft so as to be rotatable and swingable, and is fixed so as to cover the opening; a stopper that fixes the position of the bearing relative to the shaft; a connecting end for transmitting a rotational driving force applied from a rotational driving device to the other end of the shaft, the connecting end being connected to the other end of the shaft;

2. 2. The tube cutting device according to claim 1, wherein the distance from the position where the shaft is supported to the position where the circular rotary blade is fixed is 50 to 300 mm.

3. 2. The tube cutting device according to claim 1, wherein an extension shaft having a universal joint is connected to the connecting end, and the rotational driving force is transmitted to the shaft via the extension shaft.

4. 2. The pipe cutting device of claim 1, further comprising a water supply passage extending through said platen.

5. A method for cutting a pipe using the pipe cutting device according to any one of claims 1 to 3, connecting the rotary drive device to the connecting end for transmitting the rotary drive force; adjusting the position of the stopper so that the rotary blade abuts on a predetermined position of the tube; a step of inserting the rotary blade into the inside of the tube from the upper end thereof and fixing the aperture plate to the upper end of the tube with the fixing means so as to cover the upper end of the tube; a step of pressing the rotary blade fixed to the shaft against the inner surface of the tube while rotating it with the rotational driving force, and moving the rotary blade in a circumferential direction to cut the tube.

6. 6. The method for cutting a pipe according to claim 5, wherein the pipe is the inner cylindrical portion of a cast iron bowl trap.

7. A pipe cutting method using the pipe cutting device according to claim 4, connecting the rotary drive device to the connecting end for transmitting the rotary drive force; adjusting the position of the stopper so that the rotary blade abuts on a predetermined position of the tube; a step of inserting the rotary blade into the inside of the tube from the upper end thereof and fixing the aperture plate to the upper end of the tube with the fixing means so as to cover the upper end of the tube; a step of pressing the rotary blade fixed to the shaft against the inner surface of the pipe while rotating it by the rotational driving force and moving the rotary blade in a circumferential direction to cut the pipe; supplying water through the water supply channel and applying the water to the circular rotary blade.

8. 8. The method for cutting a pipe according to claim 7, wherein the pipe is the inner cylindrical portion of a cast iron bowl trap.

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