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 passes through horizontal branch pipes that lead to drains in the rooms where each facility is located, and then flows into a sewage tank or other facility via a shared drainage standpipe that runs through each floor.

[0003] A drain trap called a bowl trap or belt trap may be installed at the drain of a bathroom in an apartment building or the like. Specifically, as shown in FIG. 11, a bowl trap (drain trap) 20 has an inner cylindrical part 21b standing from a bottom part 21a, a bottomed cylindrical trap body 21 with an open top, and a bowl-shaped body 22 that is placed on the inner cylindrical part 21b, and has a connecting screw part 21c that extends downward from the inner cylindrical part 21b. A drainage strainer 23 is disposed at the open drain of the bowl trap 20. The bowl trap 20 is connected to a horizontal drain pipe 25 embedded in the slab via the connecting screw part 21c, and drains into a sewer pipe through a drain standpipe (not shown) that leads to the horizontal drain pipe 25.

[0004] If such a drain trap is made of metal such as cast iron, it may deteriorate over the years and develop rust after several decades of use, causing breaks and water leakage. To stop such leakage, a method of repairing the drain trap is known.

[0005] For example, the following Patent Document 1 provides a bathroom drain repair method that can share as much as possible the work to restore the function of the outflow flow path around the drain trap body and the work to connect the unit drain pipe to the outflow flow path when the bathroom is unitized. Patent Document 1 also discloses a repair method that rehabilitates the drain inlet in place of the removed inner cylindrical part by removing the inner cylindrical part of the drain trap that has deteriorated over time, inserting an inner pipe made of polyvinyl chloride into the cylindrical part that remains in the part where the inner cylindrical part was removed, and filling the gap between the cylindrical part and the inner pipe with a water-stopping agent.

[0006] Patent Document 1 discloses methods for removing the inner tube, such as using a hole saw to cut off the inner tube from above, or cutting off the outer half of the inner tube and then breaking off 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, the method disclosed in Patent Document 1, in which the inner cylinder is ground from above, or the outer half is ground, and then the remaining part is broken with a steel rod or the like, generates a large amount of dust during grinding and takes a long time to complete, making it an inefficient method. Also, the method of making multiple vertical cuts with a saber saw is difficult for hard materials such as cast iron, and is not a practical method.

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

[0009] In addition, 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 toward the shank from the cutter blade to trace the edge of the pipe.

[0010] According to the pipe cutter described in Patent Document 2, a fitting seat equipped with a means for pressing against the circumferential wall of the pipe to fix the inserted state of the pipe cutter is provided on the tip side of the blade plate, so it seems difficult to cut deep parts such as near the base of the inner cylindrical part of a drain trap. Also, with such a pipe cutter, since the fitting seat is made of an elastic material such as rubber, it is 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 seems 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 end 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 hard cast iron drain traps. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent 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 rotating 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 for inserting one end of a pipe into the 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 for covering one end of the pipe with the shaft inserted through an opening provided in the center at a predetermined distance from the rotary blade, a fixing means for fixing the aperture plate to the one end of the pipe, a bearing fixed to cover the opening and supporting the shaft rotatably and swingably, a stopper for fixing 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 other end of the shaft. According to this pipe cutting device, the aperture plate, to which the bearing for supporting the shaft rotatably and swingably is fixed, is fixed to one end of the pipe by the fixing means, so that the rotary blade fixed to the tip of the shaft can be rotated in the circumferential direction with the bearing as the fulcrum of the shaft by the action of an operator tilting the rotary drive device. This allows the rotary blade to trace the inner surface of the tube 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 tube to be cut by the principle of leverage. Also, since the platen to which the bearing is fixed has an outer diameter that covers one end of the tube, the platen covers one end of the tube when cutting the tube, so that dust generated during cutting can be contained inside the tube.

[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 be 50 to 300 mm, since this allows the rotary blade to be pressed against the part to be cut with greater force without significantly bending the shaft.

[0016] In addition, it is preferable that the cutting device has an extension shaft having a universal joint connected to the connecting end, and the rotational drive force is transmitted to the shaft via the extension shaft. When an obstacle such as a bathtub or a wall is present around the pipe to be cut, it may be difficult to secure sufficient space for the operator to tilt the rotational drive device and move it in the circumferential direction. In such a case, by connecting an extension shaft having a universal joint to the connecting end of the tip of the shaft, even if the space to sufficiently tilt the rotational drive device cannot be secured due to interference with the obstacle, the shaft can be sufficiently tilted by bending the extension shaft. In other words, the angle at which the operator must tilt the rotational drive device to sufficiently tilt the shaft 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 through the water supply passage to the rotating blade that cuts the pipe to cool the rotating blade, thereby extending the service life of the rotating blade before it becomes worn out and difficult to use.

[0018] Another aspect of the present invention is a method for cutting a pipe using the above pipe cutting device, comprising the steps of: connecting a rotary drive device for transmitting a rotary drive force to the connecting end; adjusting the position of a stopper so that the circular rotary blade abuts on a predetermined position of 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 rotary drive force, and moving the circular rotary blade in the circumferential direction to cut the pipe. According to this pipe cutting method, by pressing the rotary blade against the part to be cut with a strong force, even a pipe made of a hard material can be efficiently cut from the inner surface without scattering a large amount of dust. Specifically, even a hard pipe such as the inner cylinder of a cast iron bowl trap can be efficiently cut without scattering a large amount of dust around. In addition, if the platen is formed with a water supply passage passing through it, water can be supplied through the water supply passage and applied to the circular rotating blade to cool it, thereby extending the service life of the rotating blade before it becomes worn out and difficult to use. Effect of the Invention

[0019] According to the present invention, the rotary blade can be pressed against the part to be cut with great 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 description 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. [Diagram 2] FIG. 2 is a schematic partial cross-sectional view of a tube cutting device 10 connected to a rotary drive device 50 according to an embodiment. [Diagram 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. [Diagram 5] FIG. 5 is a process schematic diagram for explaining 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 schematic diagram for explaining 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 schematic diagram for explaining 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 for explaining a state in which a bathtub 60 is in the vicinity 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 the cast iron bowl trap of the embodiment. [Figure 10] FIG. 10 is a schematic partial cross-sectional view of a pipe cutting device 110 provided with a water supply passage 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 PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, 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 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 of this embodiment, and Fig. 2 is a schematic partial cross-sectional view of the cutting device 10. Figs. 1 and 2 show a state in which a rotation drive device 50 is connected to the cutting device 10. In this embodiment, the rotation drive device 50 is an electric screwdriver. In the following description, the lower side of the paper surface may be referred to as the leading end side, and the upper side of the paper surface may be referred to as the rear end side.

[0023] In Figures 1 and 2, 1 is a shaft, 2 is a circular rotating 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 covering the opening 3a and supporting 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 rotation 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 fixed to the shaft 1 to adjust the position of the aperture plate 3.

[0024] FIG. 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 nut 2a. Also, referring to Fig. 1 and 4, the shaft 1 is inserted into an opening 3a of a circular opening 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 for supporting the shaft 1 so that the shaft 1 is rotatable and swingable.

[0027] The platen 3 is a member that supports the bearing 5 and has an outer diameter that caps 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 is no particular limitation on the method of fixing the bearing to the platen, and it may be, for example, by bolting the bearing to the upper surface of the platen via a flange, or by fitting the bearing into the opening of the platen and fixing it by welding.

[0028] The bearing 5 has a mechanism for supporting the shaft 1 so as to be rotatable and swingable. Such a bearing is usually also called an aligning bearing. In this embodiment, referring to Fig. 2 and Fig. 4, the bearing 5 includes an inner ring 5a through which the shaft 1 is inserted and supported, a rolling element 5b, an outer ring 5c ​​provided on the outside of the rolling element 5b, and a housing 5d that supports the outer ring 5c. The outer ring 5c ​​has an outer peripheral surface that is a convex spherical surface, and the housing 5d has an inner peripheral surface that is a concave spherical surface.

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

[0030] 2 and 4, a fixing means 4 for fixing the aperture plate 3 to one end of the tube 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 along a slightly inner side of 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 penetrating the platen 3, and their tip portions are housed in recesses r1 and r2 provided in the holding members 4a and 4b after penetrating the platen 3. By tightening and advancing the bolts 4c and 4d fitted into the threaded holes provided in the platen 3, the wall surfaces of the recesses r1 and r2 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, 4h are housed in recesses r3, r4, r5, r6, respectively, and pressing members 4a, 4b are spread outward from platen 3, whereby guide pins 4e, 4f, 4g, 4h are pressed against the wall surfaces of recesses r3, r4, r5, r6, respectively, and fix the spread pressing members 4a, 4b, respectively. In this way, pressing members 4a, 4b are pressed against the inner surface of the tube by spreading out each of the pressing members 4a, 4b from the inner surface of the tube end, and platen 3 is fixed to 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 the above form, and for example, the pressing member can be omitted and the tip of a bolt fitted into a plurality of screw holes provided in the opening plate can be tightened so as to press 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., as 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 in order to adjust the position of the aperture plate 3. The stopper 8 is a member fixed to the shaft 1 by inserting the shaft 1 therethrough, 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 fixed to the shaft 1. The stopper 8 presses the upper end of the bearing 5, thereby making it possible to adjust the distance from the position at which 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 screw hole of 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 shaft 1 is supported to the position where circular rotary blade 2 is fixed, which is adjusted by stopper 8, can be adjusted as appropriate; for example, when cutting the inner cylindrical portion of a cast iron bowl trap, it is preferable for the distance to be 50 to 300 mm, further 50 to 200 mm, and particularly 50 to 100 mm, because this allows the rotary blade to be pressed with greater force against the part to be cut 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 interposed 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 screw thread (not shown) engraved on the tip of the shaft 1.

[0038] The rotary blade is a circular rotary blade with a diameter smaller than the inner diameter of the pipe to be cut, and is a cutting member that cuts the pipe by applying the blade on the circumferential surface to the pipe to be cut. For example, when cutting a hard material such as the inner cylinder of a cast iron bowl trap, a rotary blade having a cutting blade made of abrasive grains, in which a plurality of hard abrasive grains such as diamond grains are attached to the outer periphery of a hard metal disk, or a circular cutting grindstone is preferably used. In addition, when cutting a soft material such as a polyvinyl chloride pipe, a rotary blade having a saw blade on 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 can 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 more preferably 40 to 60 mm.

[0040] The shaft 1 has a connection end 6 at its rear end for connecting the rotation drive unit 50. The connection end 6 is a portion for connecting the rotation drive unit 50, and is a portion for directly or indirectly fixing the shaft 1 to the rotation drive unit 50 and transmitting the rotation drive force applied from the rotation drive unit 50 to the shaft 1. The connection end 6 may be a round shaft (straight shank) fixed by the chuck of a normal 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 via a chuck, and a bolt or nut that fits into the socket is connected to the tip of the shaft 1.

[0041] The shaft 1 and the rotary drive device 50 are connected through the connection end 6. The rotary drive device 50 is a device that applies a rotary drive force to the shaft 1, and is preferably a device that an operator can hold to tilt the shaft 1. In this embodiment, referring to FIG. 1, an electric screwdriver is illustrated that includes a trigger switch 50a that an operator presses with his / her 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 fixes the connection end 6 of the shaft 1. When the trigger switch 50a is pressed and turned ON, the rotary drive device 50 applies a rotary drive force to the shaft 1 and rotates the rotary blade 2 fixed to the tip of the shaft 1.

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

[0043] In the cutting method of this embodiment, the trap body 21 of the bowl trap made of cast iron to be cut is prepared as shown in Fig. 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, 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, when the shaft 1 is tilted, the rotary blade 2 hits the intended predetermined cutting position A on the inner cylindrical portion 21b of the trap body 21. This adjustment of the distance 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 comes into contact with the cutting position A, the operator advances the rotary blade 2 fixed to the tip side of the cutting device 10 from the upper end into the inner cylinder 21b to be cut. Then, the opening plate 3 is fixed to the upper end of the inner cylinder 21b by the fixing means 4. Specifically, after the opening plate 3 is set so as to cover the upper end of the inner cylinder 21b, the bolts 4c and 4d of the fixing means 4 fitted into the screw holes penetrating the opening plate 3 are tightened. By tightening the bolts 4c and 4d, the pressing members 4a and 4b are opened so as to be pushed apart by the inner surface of the inner cylinder 21b, and the pressing members 4a and 4b are pressed against the inner surface of the inner cylinder 21b, and the opening plate 3 is fixed. In this way, the cutting device 10 is set to the inner cylinder 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 rotates the shaft 1 as the motor (not shown) of the rotary drive device 50 is driven. 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 cylinder 21b at the height of the predetermined cutting position A.

[0047] Then, after a part of the cutting position A of the inner cylinder portion 21b is cut, the rotary drive device 50 is tilted and moved so as to trace the inner wall of the inner cylinder portion 21b in the circumferential direction, so that the rotary blade 2 is pressed against other parts of the inner cylinder portion 21b at the height of the predetermined cutting position A. In this way, the entire surface of the inner cylinder portion 21b is cut by sequentially moving the rotary blade 2 so as to trace the circumferential direction horizontally at the height of the predetermined cutting position A. Since the bearing 5 that supports the shaft 1 of the cutting device 10 is freely swingable with respect to the shaft 1, the rotary blade 2 fixed to the tip of the shaft 1 can freely swing in the circumferential direction. In cutting the inner cylinder portion 21b, the bearing 5 provided in the cutting device 10 serves as a fulcrum of the lever, so that the rotary blade 2 can be pressed against the inner surface of the inner cylinder portion 21b with a strong force. Therefore, even if the inner cylinder portion 21b is made of a hard material such as cast iron, it can be cut efficiently in a relatively short time.

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

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

[0050] In the above cutting method, when 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 sufficiently tilt or move the rotary drive device 50. Specifically, for example, as shown in Fig. 8, when the trap body 21 of the bowl trap is disposed adjacent to the bathtub 60, when the worker tilts the rotary drive device 50 and moves it to trace the inner wall of the inner cylindrical portion 21b in the circumferential direction, 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 unit 50 to the connection end 6 of the shaft 1, the angle at which the operator tilts the rotational driving unit 50 in order to bring the rotary blade 2 into contact with the inner tube portion 21b of the shaft 1 can be reduced.

[0052] Referring to FIG. 9, an extension shaft 11 having a universal joint 11b is connected to a connecting end 6 of a shaft 1. A universal joint is a joint that can freely change the angle at which two members are joined. 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 not particularly limited, but is preferably, for example, 200 to 1000 mm, and more preferably, 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 connection end 6 of the shaft 1. The cover 11c is a cylindrical member through which the extension shaft body 11a is inserted, and is provided with bearings 11e and 11f that rotatably support the extension shaft body 11a. The cover 11c is a safety means that prevents the rotating extension shaft body 11a from being exposed.

[0054] 9, by connecting the extension shaft 11 having the 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 device 50 in order to sufficiently tilt the shaft 1. Furthermore, since the rotation drive force is transmitted to the shaft 1 via the extension shaft 11, even if a sufficient space cannot be secured for tilting the rotation drive device 50, the entire surface of the inner cylinder portion 21b can be cut by sequentially moving the rotary blade 2 horizontally to 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 cylinder portion 21b in the horizontal direction at the predetermined cutting position A. In addition, the opening plate covers the inner cylinder portion 21b, so that dust generated during cutting can be prevented from flying up to the work area during the cutting operation.

[0056] An embodiment of the pipe cutting device and pipe cutting method according to the present invention has been described in detail above. 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 exemplified.

[0057] When the above-mentioned pipe cutting device 10 is used to cut a hard pipe such as the inner cylinder of a bowl trap made of cast iron, the circular rotary blade 2 cuts hard cast iron, so that the blade of the rotary blade 2 may wear out due to frictional heat generated during cutting, making it difficult to use the rotary blade in a relatively short time. In such a case, 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 generated during cutting, and the service life of the rotary blade 2 can be improved. A cutting device 110 according to another embodiment that can cut a pipe while applying water to the rotary blade 2 to cool it in this way will be described with reference to FIG. 10.

[0058] Fig. 10 is a partial cross-sectional schematic diagram of a cutting device 110 connected to a rotary drive device 50, which has the same configuration and function as the cutting device 10 described above, except that the cutting device 110 uses an aperture plate 13 having a water supply passage 30 penetrating the aperture plate. In the cutting device 110 shown in Fig. 10, a through hole H is formed in the aperture plate 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 joints 33, 34 are connected to the threads of through hole H, with short hose 32 connected to male threaded hose joint 34 and water supply hose 31 connected to male threaded hose joint 33. Water supply hose 31 is connected to a water supply means such as a waterworks or water supply pump (not shown). In addition, short hose 32 guides the water supplied from water supply hose 31 to hit rotary blade 2. These form water supply passage 30 for hitting the circular rotary blade with water.

[0060] In carrying out the pipe cutting method, by adopting such a cutting device 110 and rotating the rotary blade 2 to cut the pipe while directing water supplied through the water supply passage 30 at the rotary blade 2 to cool it, 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. [Explanation of symbols]

[0061] 1 Shaft 2 Rotary blade 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 screen 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, 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 tube; an aperture plate having an outer diameter for capping one end of the tube, the aperture being provided in the center of the aperture at a predetermined distance from the rotary blade and through which the shaft is inserted; a fastening means for fastening the disk to one end of the tube; a bearing that supports the shaft so as to be rotatable and swingable, the bearing being 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 provided with the rotational driving force from the rotational driving device.

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 of 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 through the extension shaft.

4. 2. The tube cutting apparatus 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 upper end of the tube and fixing the 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 the rotary blade by 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 method for cutting a tube using the tube cutting device according to claim 4, comprising the steps of: 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 upper end of the tube and fixing the 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 the rotary blade by the rotational driving force and moving the rotary blade in a circumferential direction to cut the pipe; supplying water through the water supply passage 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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