How to cut a fluid pipe

Abstract

A method for cutting a fluid pipe is provided that allows the shape of a perforated portion in the fluid pipe to be formed with a high degree of freedom and maintains the structural strength of the fluid pipe. [Solution] A method for cutting a fluid pipe (2) in which cutters (72A, 72B) as punching tools that can rotate around an advance / retract shaft (73a) are moved downward within a case body (20) that is hermetically attached to the outer peripheral surface of the fluid pipe (2), thereby cutting the fluid pipe (2) by providing a plurality of punching sections (h1, h2) in series on the outer peripheral surface of the fluid pipe (2), and the method includes at least a first punching step in which cutter (72A) as a first punching tool is used to form punching section (h1) on the outer peripheral surface of the fluid pipe (2), and a second punching step in which cutter (72B) as a second punching tool that is a different type from cutter (72A) is used to form punching section (h2) on the outer peripheral surface of the fluid pipe (2).

Description

[Technical Field]

[0001] The present invention relates to a method for cutting a fluid pipe by forming a plurality of perforated portions in series on the outer surface of the fluid pipe. [Background technology]

[0002] Conventionally, a method for cutting a fluid pipe includes, for example, a method of cutting the fluid pipe by using a hole saw as a drilling tool to continuously form a plurality of perforations on the outer surface of the fluid pipe.

[0003] One method for cutting this type of fluid pipe involves, for example, using a hole saw that is larger than the radius of the fluid pipe but smaller than the outer diameter of the fluid pipe to form a first perforation section at a first perforation center position displaced to one side relative to the axis of the fluid pipe, and then connecting a second perforation section to the first perforation section at a second perforation center position displaced to the other side relative to the axis of the fluid pipe, thereby cutting the fluid pipe so that the width dimension in the axial direction of the pipe becomes the valve insertion set width (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-117785 A (pages 9 and 10, Figure 13) Summary of the Invention [Problem to be solved by the invention]

[0005] In the pipe cutting method described in Patent Document 1, the first and second perforation sections are formed using a common hole saw, and therefore the perforation surface of the perforation section formed in the fluid pipe is formed with a curved surface having the same curvature as the hole saw over the entire surface. As a result, the shape of the perforation section cannot be freely designed, and the shape of the final cut section consisting of multiple connected perforation sections ends up being formed with an unnecessarily curved shape, which creates the risk of reducing the structural strength of the fluid pipe after the cut section is formed.

[0006] The present invention has been made in response to these problems, and aims to provide a method for cutting a fluid pipe that allows for a high degree of freedom in the shape of the perforation in the fluid pipe and maintains the structural strength of the fluid pipe. [Means for solving the problem]

[0007] In order to solve the above problems, the method for cutting a fluid pipe of the present invention includes: A method for cutting a fluid pipe, comprising: moving a rotatable punching tool around a rotation axis within a case body that is hermetically attached to an outer surface of the fluid pipe, thereby cutting the fluid pipe by forming a plurality of punching portions in series on the outer surface of the fluid pipe, forming a first perforated portion on an outer surface of the fluid pipe using a first perforation tool; The method is characterized by at least comprising a step of forming a second piercing portion on the outer surface of the fluid pipe using a second piercing tool that is different in type from the first piercing tool. According to this feature, by connecting multiple drilling sections in a fluid pipe using different types of drilling tools, the shape of the drilling sections in the fluid pipe can be formed with a high degree of freedom regardless of the shape of each drilling tool, while maintaining the structural strength of the fluid pipe after drilling.

[0008] In the step of forming the first piercing portion, a cylindrical cutter having a diameter larger than the radius of the fluid pipe and smaller than the diameter of the fluid pipe is used as the first piercing tool, In the step of forming the second perforated portion, a cylindrical cutter having a radius smaller than that of the fluid pipe is used as the second perforation tool. According to this feature, the large first perforation portion and the small second perforation portion allow the perforation portion to be formed with a high degree of freedom.

[0009] The step of forming the second perforated portions is carried out a plurality of times, and a plurality of the second perforated portions are provided in series in the tube axial direction. According to this feature, a large opening width in the axial direction of the tube can be ensured without using a punching tool with a large outer diameter.

[0010] forming the first perforated portion at a substantially central position in the radial direction on the outer surface of the fluid pipe using the first perforation tool; The method is characterized by including a step of using the second piercing tool to form the second piercing sections connected to the first piercing section at both radial positions on the outer surface of the fluid pipe. According to this feature, cutting is possible by providing a plurality of perforated portions in series.

[0011] The method is characterized in that an opening / closing valve having a partition wall portion arranged to separate the interior of the case body and a valve body rotatably mounted relative to the partition wall portion for opening and closing the interior of the partition wall portion is inserted into the cut portion of the fluid pipe formed inside the case body, with the valve body inclined relative to the partition wall portion in an effective open state and the valve body spaced apart from the cut portion of the fluid pipe. According to this feature, the on-off valve can be inserted without interfering with the cut portion of the fluid pipe, while maintaining an uninterrupted flow of the fluid inside the fluid pipe.

[0012] At least one of the first punching tool and the second punching tool is a cylindrical cutter including a center drill and a hole saw, The method further comprises a step of fixing a guide material having a flat surface that can be penetrated by the center drill or the hole saw to the outer surface of the fluid pipe so that the flat surface is approximately perpendicular to the direction of movement of the cutter. This feature makes it possible to suppress axial wobble of the hole saw. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a cutting device used in a fluid pipe cutting method according to an embodiment of the present invention. [Figure 2] 1(a) is a plan view showing the state in which the lower case is attached to the existing fluid pipe, and FIG. 1(b) is a vertical cross-sectional view. [Figure 3] 1(a) is a plan view showing a state in which a first perforation step is performed by a cutting device, and FIG. 1(b) is a longitudinal sectional view. [Figure 4]10(a) is a plan view showing the state in which the second perforation step is performed by the cutting device, and FIG. 10(b) is a longitudinal sectional view. [Figure 5] 10(a) is a plan view showing the state after the second perforation step by the cutting device has been completed, and FIG. 10(b) is a longitudinal sectional view. [Figure 6] FIG. 10 is a longitudinal cross-sectional view showing a state before the butterfly valve is inserted into the cutting portion by the insertion device. [Figure 7] FIG. 10 is a longitudinal cross-sectional view showing a state in which the butterfly valve is inserted into the cut portion by the insertion device. [Figure 8] FIG. 4 is a vertical cross-sectional view showing a state in which the butterfly valve is installed in the cutting section. [Figure 9] FIG. 10 is a plan view showing the state in which the butterfly valve is opened and inserted into the cutting section. [Figure 10] 10(a) is a plan view showing the state in which the second perforation step is performed by the cutting device, and FIG. 10(b) is a longitudinal sectional view. [Figure 11] 1(a) is a plan view showing a state in which a first perforation step is performed by a cutting device, and FIG. 1(b) is a longitudinal sectional view. [Figure 12] 1A is a plan view showing the state after the first perforation step by the cutting device has been completed, and FIG. 1B is a longitudinal sectional view. [Figure 13] (a) is a plan view showing the state in which the first drilling step is being carried out in the method for cutting a fluid pipe as variant 1 of the present invention, (b) is a plan view showing the state in which the second drilling step is being carried out, and (c) is a plan view showing the state in which the second drilling step has been completed. [Figure 14] 10 is a plan view showing a state in which the butterfly valve is opened and inserted into the cutting section in the fluid pipe cutting method according to the first modified example of the present invention. FIG. [Figure 15] 10(a) and 10(b) are plan views showing a state in which a second drilling step is being carried out in the fluid pipe cutting method according to the first modified example of the present invention, and 10(c) is a plan view showing a state in which the first drilling step has been completed. [Figure 16] 10(a) and 10(b) are plan views showing a method for cutting a fluid pipe according to a second modification of the present invention. [Figure 17]As a variant example 3 of the present invention, (a) is a longitudinal cross-sectional view showing the state in which a through hole is formed in the lower part of a fluid pipe to prevent axial wobble by a center drill, and (b) is a longitudinal cross-sectional view showing the state in which the subsequent first or second drilling step is carried out. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid pipe cutting method according to the present invention will be described below with reference to the following examples. [Example]

[0015] A method for cutting a fluid pipe according to an embodiment of the present invention will be described with reference to Figures 1 to 9. In the following description, the right side of Figure 1 will be referred to as the front of the cutting device, the left side as the rear, the near side as the left side, and the far side as the right side.

[0016] As shown in Figure 1, a fluid pipe cutting device 1 used when carrying out the fluid pipe cutting method of the present invention is hermetically attached to a predetermined location of a fluid pipe 2 that constitutes an existing flow path. The fluid in the fluid pipe 2 is tap water in this embodiment, but is not limited to this and may be, for example, industrial water, agricultural water, sewage, or a gas or a gas-liquid mixture of gas and liquid.

[0017] The fluid pipe 2 according to the present invention is formed of a straight steel pipe having a generally circular cross section. In this embodiment, the fluid pipe 2 is disposed in a generally horizontal direction. The fluid pipe according to the present invention may be made of metal such as ductile cast iron or other cast iron, or may be made of concrete, vinyl chloride, polyethylene, polyolefin, or the like. Furthermore, the inner circumferential surface of the fluid pipe may be coated with an epoxy resin layer, mortar, plating, or the like, or may be coated with an appropriate material by powder coating.

[0018] [Fluid pipe cutting device] As shown in Figure 1, the cutting device 1 is mainly composed of a lower case 3 that is attached in a sealed manner to surround the outer surface of an existing fluid pipe 2, a gate valve device 50 that is attached above the lower case 3, and a drive mechanism unit 70 that is attached above the gate valve device 50, and is capable of cutting the fluid pipe 2 by forming multiple perforations at predetermined locations on the outer surface of the fluid pipe 2 in a state where flow is not interrupted.

[0019] [Lower case] 1 and 2(a) and (b), the lower case 3 is mainly composed of a main portion 5 formed in a generally rectangular tubular shape in plan view with an opening at the top, cylindrical side portions 6, 6 protruding from the left and right walls of the main portion 5 in directions perpendicular to the axis of the main portion 5 and capable of covering the fluid pipe 2, and a bottom portion 7 closing the lower opening of the main portion 5, and each portion is welded to each other. Note that the components constituting the lower case 3 and the like are not limited to those which are welded together and integrated as in this embodiment, but may also be formed integrally by casting or the like.

[0020] The main section 5 and side sections 6, 6 are divided into two sections, one above the other, along the pipe axis of the side sections 6, 6: an upper section 3a that is generally inverted T-shaped when viewed from the front, and a lower section 3b that is generally T-shaped when viewed from the front, and the lower section 3b covers the lower part of the fluid pipe 2, while the upper section 3a covers the upper part of the fluid pipe 2, and the lower section 3b and the upper section 3a are joined by welding, thereby hermetically attaching the sections so as to cover predetermined portions of the fluid pipe 2. The side sections 6, 6 are hermetically fitted onto the outer peripheral surface of the fluid pipe 2, and both ends in the pipe axis direction are welded to the fluid pipe 2 by divided plate-shaped annular members 10, 10, thereby hermetically fixing the sections.

[0021] Although the lower case 3 in this embodiment is composed of two segments (upper segment 3a and lower segment 3b), it may be composed of three or more segments. Furthermore, although the upper segment 3a and lower segment 3b are hermetically joined by welding in this embodiment, they may be joined by a plurality of fastening members such as bolts and nuts.

[0022] A steel seat 8 projects from the inner surface of the lower case 3 and receives the butterfly valve 4 (see FIG. 6) inserted from the upper opening of the lower case 3. Specifically, the seat 8 is composed of a lower seat 8a extending in the front-to-rear direction (the direction perpendicular to the pipe axis) so as to pass through approximately the center of the bottom 7 of the lower case 3, which is circular in plan view, vertical seat portions 8b, 8b extending upward from the front and rear ends of the lower seat 8a along the inner surface of the main portion 5, and an upper seat 8c connected to the upper ends of the vertical seat portions 8b, 8b and extending in the circumferential direction around the inner surface of the main portion 5 in the shape of a substantially rectangular frame. The longitudinal center position of the lower seat 8a is circular in plan view.

[0023] A pair of left and right guide portions 14, 14 and 15, 15 that guide the butterfly valve 4 (see FIG. 6) downward are provided on the left and right sides of the vertical seats 8b, 8b. The guide portions 14, 14, 15, 15 protrude radially inward beyond the contact surfaces of the vertical seats 8b, 8b, and extend vertically along the vertical seats 8b, 8b, at positions slightly spaced apart on the left and right sides from the vertical seats 8b, 8b.

[0024] A plurality of cylindrical portions 27 projecting outward are formed in the circumferential direction at positions above the upper seat portion 8c on the lower outer peripheral surface of the main portion 5. A threaded hole (not shown) is formed inside each cylindrical portion 27, and a fixing pin 28 is screwed into the threaded hole in a sealed manner toward the inside of the main portion 5. The fixing pin 28 can be rotated around its axis from the outside of the cylindrical portion 27 with a tool or the like to retract the tip of the fixing pin 28 into the cylindrical portion 27, thereby allowing the butterfly valve 4 (see FIG. 6) to be inserted, or the tip of the fixing pin 28 can be protruded into the main portion 5 and abutted against the upper surface of the upper cover portion 81, thereby fixing the butterfly valve 4 (see FIG. 8). The tip of the fixing pin 28 is tapered toward the inner diameter.

[0025] [Gate valve device] 1, the gate valve device 50 has a valve box 50a in the shape of a rectangular cylinder that penetrates vertically, a valve cover 50b (see FIG. 6) that protrudes to the right from the valve box 50a and is connected to the valve box 50a via a communication port (not shown) formed on the inner peripheral surface, a gate valve element 50c that is provided between the valve box 50a and the valve cover 50b so as to be movable in a substantially horizontal direction, and a recessed groove 50d that serves as a valve seat for receiving the gate valve element 50c. The recessed groove 50d allows the gate valve element 50c to abut in a sealed manner via a seal member (not shown).

[0026] As shown in Figure 6, the end of a valve stem 50h that is threadedly engaged with the gate valve body 50c inside the valve lid 50b protrudes from the tip of the valve lid 50b, and an operating part (not shown) is provided at the end of this valve stem 50h, so that the interior of the lower case 3 can be opened and closed by using the operating part (not shown) to move the gate valve body 50c between the valve box 50a and the valve lid 50b.

[0027] As shown in Figure 1, flanges 50e, 50f that protrude outward from the main part 5 are formed on the periphery of the upper and lower openings of the valve box 50a, and by fastening the lower flange 50e to the flange 3e of the main part 5 with multiple fastening members (not shown) consisting of bolts and nuts arranged circumferentially, the valve box 50a is hermetically connected to the upper opening (opening) of the main part 5 via a sealing member (not shown).

[0028] [Drive mechanism] 1, the drive mechanism 70 is mainly composed of a mounting flange tube 71 formed in a rectangular cylindrical shape, a cutter 72A as a punching tool capable of punching holes in the fluid pipe 2, a drive motor (not shown) for rotating the cutter 72A inside the mounting flange tube 71, an advance / retract mechanism 73 for moving the cutter 72A up and down, and a cover member 74A for closing the top opening of the mounting flange tube 71. The cover member 74A has a through-hole 75a at a position forward of the center in the front-to-rear direction, through which the advance / retract shaft 73a of the advance / retract mechanism 73 can be inserted in the up and down direction.

[0029] Cutter 72A is mainly composed of a cylindrical hole saw 72a with a cutting blade 72d at its lower end along the circumferential direction, and a center drill 72b disposed coaxially within hole saw 72a and retractable shaft 73a. Cutting blade 72d at the lower end of hole saw 72a is located below center drill 72b.

[0030] The cutter 72A is supported forward of the center position of the cover member 74A so as to be rotatable about the advancing / retracting shaft 73a and so as to be movable in the vertical direction between a drilling standby position within the mounting flange cylinder 71 and a drilling completion position where the cutter 72A is inserted into the main part 5 of the lower case 3 from the upper opening in the main part 5 and penetrates at least the wall of the fluid pipe 2. The hole saw 72a has an outer diameter L11 that is larger than the radius La1 of the fluid pipe 2 and smaller than the outer diameter L1 (La1 <L11<L1)。

[0031] Flanges 71a, 71b that protrude outward from the main portion 5 are formed on the periphery of the upper and lower openings of the mounting flange tube 71, and the drive mechanism portion 70 is hermetically connected to the upper opening of the valve box 50a via a seal member (not shown) by fastening the lower flange 71a to the flange 50f of the gate valve device 50 with a plurality of fastening members (not shown) made of bolts and nuts arranged circumferentially. Also, the lid member 74A is hermetically connected to the upper opening of the mounting flange tube 71 via a seal member (not shown) by fastening the periphery of the cover member 74A to the upper flange 71b with a plurality of fastening members (not shown) made of bolts and nuts arranged circumferentially.

[0032] Also, as shown in FIG. 1, a case body 20 as an embodiment of the present invention that is hermetically attached to the outer surface of the fluid pipe 2 is constituted by the lower case 3, the valve box 50a, the valve lid 50b of the partition valve device 50, and the mounting flange cylinder 71. As shown in FIG. 2(a), the case body 20 is formed in a substantially rectangular shape in plan view. The front-rear dimension L2 of the inner surface is larger than the outer diameter dimension L1 of the fluid pipe 2 (L2 > L1), and the left-right dimension L3 of the inner surface is smaller than the outer diameter dimension L1 of the fluid pipe 2 (L3 < L1). Further, the front-rear dimension L2 and the left-right dimension L3 are larger than the outer diameter dimension L11 (see FIG. 1) of the hole saw 72a (L2 > L11, L3 > L11).

[0033] Next, based on FIGS. 1, 3 to 9, the process of installing the butterfly valve 4 inside the lower case 3 in a non-stop flow state will be described. In this embodiment, since it is necessary to cut the fluid pipe 2 before installing the butterfly valve 4, the process will be described starting from the cutting process of the fluid pipe 2. In FIGS. 3 and later, in order to make the perforated part easier to understand, the area corresponding to the outer peripheral surface in the plan view showing the fluid pipe 2 is indicated by dots.

[0034] [Cutting process of fluid pipe] First, based on FIGS. 1 and 3 to 5, the process of cutting a predetermined portion of the fluid pipe 2 in a non-stop flow state will be described.

[0035] In this embodiment, when cutting the fluid pipe 2, first, as shown in Figure 3, a first drilling step is performed to form a drilled portion h1 centered at a first drilling position T11 that is offset forward from the pipe axis T1 on the outer surface of the fluid pipe 2 using a cutter 72A as a first drilling tool consisting of a hole saw 72a having an outer diameter L11 that is larger than the radius La1 of the fluid pipe 2 but smaller than the outer diameter L1.Then, as shown in Figures 4 and 5, a second drilling step is performed to form a drilled portion h2 that is connected to the drilled portion h1 and centered at a second drilling position T12 that is the same position in the pipe axis direction as the first drilling position T11 and is offset rearward from the pipe axis T1 on the outer surface of the fluid pipe 2. That is, the fluid pipe 2 is cut (divided) at a predetermined location by providing two perforated portions h1, h2 in a radial direction of the fluid pipe 2. The cutting step will be specifically described below.

[0036] First, as shown in Figure 1, the lower case 3 is attached in a sealed manner to a predetermined location on the fluid pipe 2, and with the lower case 3 attached, a metal guide material 41 is fixed to the upper position of the outer surface of the fluid pipe 2 at the first drilling position T11 (see Figure 3(a)) through which the center drill 72b of the cutter 72A penetrates, and a metal guide material 42 is fixed to the second drilling position T12 (see Figure 4(a)) through which the center drill 72b of the cutter 72B penetrates.

[0037] 3(b), the guide member 41 is formed into a generally downward U-shape in side view by a horizontal plate 41a that is arranged generally horizontally and has a rectangular shape in plan view, and vertical plates 41b, 41b that bend downward from the front and rear sides of the horizontal plate 41a, and the vertical plates 41b, 41b are arranged along the pipe axis T1, and the lower sides of the vertical plates 41b, 41b are abutted against the outer peripheral surface of the fluid pipe 2 and fixed at welded parts 41y, so that the guide member 41 is welded to the outer peripheral surface of the fluid pipe 2. The upper surface 41c is formed as a flat surface.

[0038] 4(b), the guide member 42 is formed into a substantially L-shape in side view by a horizontal plate 42a that is arranged substantially horizontally and has a rectangular shape in plan view, and a vertical plate 42b that bends downward from the rear side of the horizontal plate 42a, the horizontal plate 42a and the vertical plate 42b are arranged along the pipe axis T1, and the front side of the horizontal plate 42a and the lower side of the vertical plate 42b are abutted against the outer peripheral surface of the fluid pipe 2 and fixed at a welded portion 42y, thereby being welded to the outer peripheral surface of the fluid pipe 2. The upper surface 42c is formed as a flat surface.

[0039] 1, the gate valve device 50 is hermetically connected to the upper opening of the main section 5, and the drive mechanism section 70 is hermetically connected to the upper opening of the valve box 50a. Also, a cover member 74A having a cutter 72A disposed thereon is hermetically connected to the upper flange 71b of the mounting flange cylinder 71 via a plurality of fastening members (not shown) made of bolts and nuts. This results in the case body 20 being hermetically attached to the outer circumferential surface of the fluid pipe 2.

[0040] With the cover member 74A attached to the top of the mounting flange cylinder 71, the cutter 72A is placed in a drilling standby position above the fluid pipe 2. In the drilling standby position, the center drill 72b is supported in an orientation facing vertically above the guide member 41, which is positioned slightly forward of the pipe axis T1 of the fluid pipe 2 inside the mounting flange cylinder 71.

[0041] 3(a), the hole saw 72a is supported by the cover member 74A so as to be rotatable about a first drilling position T11 set at approximately the center of the upper surface 41c of the guide member 41. The hole saw 72a is also positioned so that the front part of the peripheral wall extends forward of the front end 2f of the outer circumferential surface of the fluid pipe 2, and the rear part of the peripheral wall passes approximately midway between the rear end 2b of the outer circumferential surface of the fluid pipe 2 and the pipe axis T1.

[0042] (1st drilling process) Next, the gate valve element 50c is retracted into the valve cover 50b (see FIG. 6) to open the gate valve device 50, and the case body 20 is filled with fluid while air is bled through an air bleed valve (not shown) provided at the top of the mounting flange tube 71. Water pressure approximately equal to that inside the fluid pipe 2 is applied to the case body 20 to check for leaks. After confirming that the air inside the case body 20 has been bled, the air bleed valve (not shown) is closed. Next, with the interior of the case body 20 and the interior of the fluid pipe 2 under approximately the same pressure, as shown in FIG. 3(b), the drive motor (not shown) of the drive mechanism 70 rotates the cutter 72A around the center drill 72b, and the advance / retract mechanism 73 advances the cutter 72A downward. As the cutter 72 rotates and descends, the center drill 72b moves in a direction that does not intersect with the pipe axis T1 of the fluid pipe 2.

[0043] Next, cutting begins when two circumferential locations, one on the left and one on the right, of the cutting blade 72d at the bottom of the hole saw 72a come into contact with the top of the fluid pipe 2. Thereafter, cutting begins when the tip of the center drill 72b comes into contact with the top surface 41c of the guide material 41. Because the cutting blade 72d at the bottom of the hole saw 72a comes into contact with the top of the outer circumferential surface of the fluid pipe 2 at two circumferential locations, one on the left and one on the right, upon initial contact, the cutting blade 72d of the hole saw 72a is unlikely to slip in the direction of the inclination of the outer circumferential surface of the fluid pipe 2 and deviate from the appropriate cutting position, allowing the cutting blade 72d to bite into the outer circumferential surface of the fluid pipe 2.

[0044] Furthermore, immediately after drilling begins, the lower end of the center drill 72b comes into contact with the upper surface 41c of the guide member 41, which is approximately perpendicular to the center drill 72b, preventing the center drill 72b from shifting from the appropriate cutting position (first drilling position T11) due to, for example, sliding in the direction of the inclination of the outer peripheral surface of the fluid pipe 2. Furthermore, by penetrating the guide member 41, the outer peripheral surface of the center drill 72b is supported by the guide member 41, making it less likely that the hole saw 72a will vibrate.

[0045] Next, when the cutting blade 72d bites into the outer peripheral surface of the fluid pipe 2 and starts cutting, the cutting blade 72d enters the outer peripheral surface of the fluid pipe 2 and cuts the fluid pipe 2 from above downward. Next, the cutter 72A further descends and cuts off a perforated portion formation region of the outer peripheral surface where a perforation will be formed.

[0046] Next, as shown by the two-dot chain line in Figure 3(b), when the hole saw 72a reaches the drilling end position, before the center drill 72b contacts the lower part of the fluid pipe 2, the drilled portion formation region on the outer surface of the fluid pipe 2 is separated from the fluid pipe 2 as a piece 2c, and a drilled portion h1 (see Figure 4(a)) is formed on the outer surface of the fluid pipe 2. The drilled portion h1 has a roughly C-shape in plan view, and extends from the upper part, through the front part, to the lower part of the outer surface of the fluid pipe 2.

[0047] Furthermore, when the cutter 72A cuts the perforated portion formation area of ​​the fluid pipe 2, the cut piece 2c is retained in the hole saw 72a by being locked by a locking portion (not shown) provided on the upper part of the center drill 72b. Thereafter, the advance / retract mechanism 73 retracts the cutter 72A together with the piece 2c into the inside of the mounting flange tube 71, and the gate valve body 50c of the gate valve device 50 is moved toward the valve box 50a, closing the inside of the lower case 3.

[0048] (Second drilling process) 4(a) and 4(b), the cover member 74B, which includes a cutter 72B made of a hole saw 72a having an outer diameter L12 smaller than the radius La1 of the fluid pipe 2 and the outer diameter L11 of the cutter 72A, is hermetically connected to the upper flange 71b of the mounting flange cylinder 71 via a plurality of fastening members (not shown) made of bolts and nuts. The cover member 74B has a through-hole 75b near the end rearward of the center in the front-to-rear direction, through which the advance / retract shaft 73a of the advance / retract mechanism 73 can be inserted in the vertical direction.

[0049] With the cover member 74B attached to the top of the mounting flange tube 71, the cutter 72B is placed in a drilling standby position above the fluid pipe 2. In the drilling standby position, the center drill 72b is supported in an orientation facing vertically above the guide member 42, which is positioned slightly rearward of the pipe axis T1 of the fluid pipe 2 within the mounting flange tube 71.

[0050] 4(a), the hole saw 72a is supported by the cover member 74B so as to be rotatable about a second drilling position T12 set at approximately the center of the upper surface 42c of the guide member 42. The hole saw 72a is also positioned so that the rear portion of the peripheral wall extends rearward beyond the rear end 2b of the outer circumferential surface of the fluid pipe 2, and the front portion of the peripheral wall overlaps the drilling portion h1.

[0051] Next, the gate valve element 50c is retracted into the valve cover 50b (see FIG. 6) to open the gate valve device 50, and the case body 20 is filled with fluid while air is bled through an air bleed valve (not shown) provided at the top of the mounting flange tube 71. Water pressure approximately equal to that inside the fluid pipe 2 is applied to the case body 20 to check for leaks. After confirming that the air inside the case body 20 has been bled, the air bleed valve (not shown) is closed. Next, with the interior of the case body 20 and the interior of the fluid pipe 2 under approximately the same pressure, as shown in FIG. 4(b), the drive motor (not shown) of the drive mechanism 70 rotates the cutter 72B about the center drill 72b, and the advance / retract mechanism 73 advances the cutter 72B downward. As the cutter 72B rotates and descends, the center drill 72b moves in a direction that does not intersect with the pipe axis T1 of the fluid pipe 2.

[0052] Next, cutting begins when the cutting blade 72d at the lower end of the hole saw 72a of the cutter 72B comes into contact with the corners of the cut edge of the drilled portion h1 of the fluid pipe 2 at two circumferential locations, one on the left and one on the right. Thereafter, cutting begins when the tip of the center drill 72b comes into contact with the upper surface 42c of the guide material 42. In this way, because the cutting blade 72d at the lower end of the hole saw 72a comes into contact with the corners of the cut edge of the drilled portion h1 at two circumferential locations, one on the left and one on the right, upon initial contact, the cutting blade 72d of the hole saw 72a is unlikely to slip in the direction of the inclination of the outer peripheral surface of the fluid pipe and deviate from the appropriate cutting position, allowing the cutting blade 72d to bite into the outer peripheral surface of the fluid pipe 2. Furthermore, immediately after drilling begins, the lower end of the center drill 72b of the cutter 72B comes into contact with the upper surface 42c of the guide member 42, which is approximately perpendicular to the center drill 72b, preventing the center drill 72b from shifting from the appropriate cutting position (second drilling position T12) due to, for example, sliding in the direction of the inclination of the outer circumferential surface of the fluid pipe 2. Furthermore, because the center drill 72b penetrates the horizontal plate 42a of the guide member 42, the outer circumferential surface of the center drill 72b is supported by the guide member 42, making it less likely that the axial wobble of the hole saw 72a of the cutter 72B will occur.

[0053] Next, when the cutting blade 72d bites into the outer peripheral surface of the fluid pipe 2 and starts cutting, the cutting blade 72d enters the outer peripheral surface of the fluid pipe 2 and cuts the fluid pipe 2 from above downward. Next, the cutter 72B further descends and cuts off the perforated portion formation region of the outer peripheral surface.

[0054] Next, as shown by the two-dot chain line in Figure 4(b), when the hole saw 72a reaches the drilling end position, before the center drill 72b contacts the lower part of the fluid pipe 2, the drilled portion formation region on the outer peripheral surface of the fluid pipe 2 is separated from the fluid pipe 2 as a slice 2d, and a drilled portion h2 (see Figure 5(a)) is formed on the outer peripheral surface of the fluid pipe 2. The drilled portion h2 extends circumferentially from the upper part to the lower part of the outer peripheral surface of the fluid pipe 2.

[0055] Furthermore, when the cutter 72B cuts the perforated portion formation region of the fluid pipe 2, the cut piece 2d is retained in the hole saw 72a by being locked by a locking portion (not shown) provided on the upper part of the center drill 72b. Thereafter, as shown in Figure 5(b), the advance / retract mechanism 73 retracts the cutter 72B together with the piece 2d into the inside of the mounting flange tube 71, and the gate valve body 50c of the gate valve device 50 is moved toward the valve box 50a, closing the inside of the lower case 3.

[0056] Incidentally, some of the foreign matter such as chips generated by drilling is discharged by water pressure together with the fluid in the pipe from a drain port (not shown) provided at the bottom of the lower case 3, but the remainder gradually sinks due to gravity over time, falling and remaining at the bottom 7 of the lower case 3. After the mounting flange tube 71 is removed from the valve box 50a and the drive mechanism 70 is removed, the foreign matter that has accumulated at the bottom 7 of the lower case 3 is discharged to the outside by a discharge device (not shown) attached to the valve box 50a.

[0057] As shown in Figure 5(a), the perforation section h1 formed in the first perforation process and the perforation section h2 formed in the second perforation process are radially connected to form a cutting section S1 extending radially in the fluid pipe 2, and the fluid pipe 2 is divided inside the lower case 3.

[0058] In the cut portion S1, the left-right dimension L21 of the opening formed on the front end 2f side of the fluid pipe 2 in the perforation portion h1, the left-right dimension L22 of the opening formed on the rear end 2b side of the fluid pipe 2 in the perforation portion h2, and the left-right dimension L23 of the connecting portion of the perforation portions h1 and h2 are narrower than the opening of the curved portion of the cut portion S1, but these left-right dimensions L21, L22, and L23 of the opening are larger than the left-right dimension L31 (see FIG. 6) of the partition wall portion 82 in the butterfly valve 4 described below (L21 > L31, L22 > L31, L23 > L31). In this way, by setting the left-right dimensions L21, L22, and L23 of the opening of the cut portion S1 to be larger than the left-right dimension L31 of the partition wall portion 82 in the butterfly valve 4 in the first and second perforation steps, the partition wall portion 82 can be inserted into the cut portion S1.

[0059] In this embodiment, the left and right dimensions L21, L22, and L23 of the opening are different from each other (L21 ≠ L22 ≠ L23), but the first drilling position T11 and the second drilling position T12 may be set so that all dimensions are approximately the same. Finally, the drive mechanism 70 is removed from the valve box 50a, thereby completing the process of cutting the fluid pipe 2.

[0060] In addition, before starting drilling, pilot holes smaller than the outer diameter of the tip of the center drill 72b may be formed in the upper surface 41c of the guide material 41 and the upper surface 42c of the guide material 42 so as to match the first drilling position T11 and the second drilling position T12.

[0061] [Butterfly valve installation process] Next, a process of installing the butterfly valve 4 in the cut section S1 inside the lower case 3 in an uninterrupted flow state using an insertion device 90 will be described with reference to FIGS.

[0062] As shown in Figure 6, first, the upper flange 50f of the valve box 50a is connected to the lower flange portion 90c of the tubular member 90a of the insertion device 90 with bolts and nuts (not shown), sealingly connecting the valve box 50a and the tubular member 90a. The butterfly valve 4 is housed within the tubular member 90a and attached to an insertion shaft 90d supported by a drive mechanism 90b so that it can move up and down. The lid portion 90f forming the upper end of the tubular member 90a has a through-hole 90e at its center in the front-to-rear direction, through which the insertion shaft 90d of the drive mechanism 90b can be inserted in the vertical direction.

[0063] The butterfly valve 4 mainly comprises an upper cover 81 capable of closing the upper opening of the main section 5, a partition wall 82 extending downward from the upper cover 81 and intersecting the fluid pipe 2 at a substantially right angle, and a circular valve element 83 rotatably supported by a valve shaft 85 (see FIG. 9) facing up and down and supported by the partition wall 82, and capable of opening and closing a substantially circular opening 86 (see FIG. 9) formed in the partition wall 82. When the butterfly valve 4 is installed, the peripheral edge of the upper cover 81 is hermetically pressed against the inner circumferential surface of the upper seat 8c via a seal material 84. When the butterfly valve 4 is installed, the peripheral edge of the partition wall 82 is pressed against the inner surfaces of the lower seat 8a and the vertical seat portions 8b, 8b via the seal material 84.

[0064] The valve element 83 has a flow-stopping surface that stops the flow of fluid, and is rotatable between an effective open state (see FIGS. 8 and 9) in which the flow-stopping surface is not parallel to the partition wall portion 82 and opens the opening 86, and a closed state (not shown) in which the flow-stopping surface is approximately parallel to the partition wall portion 82 and closes the opening 86. In other words, by operating the valve shaft 85, the valve element 83 rotates to open and close the opening 86. Here, the effective open state refers to a state in which the valve element 83 is open and allows an appropriate amount of fluid to flow to maintain an uninterrupted flow.

[0065] Here, when the butterfly valve 4 is installed in the cut section S1 in the lower case 3, the water-stopping surface of the valve body 83 is inclined at a predetermined angle θ1 (for example, θ1 = 30 degrees) relative to the partition wall section 82 to fix the valve body 83 in position, and the opening 86 is left in an effectively open state (see Figure 9).

[0066] Next, a hole (not shown) formed in the upper part of the lower case 3 is connected to a hole (not shown) formed in the lower part of the tubular member 90a with a connecting pipe (not shown) to communicate between the inside of the lower case 3 and the inside of the tubular member 90a, and the lower case 3 is filled with fluid while air is released from an air release valve (not shown) provided at the top of the tubular member 90a. After checking for leaks by applying water pressure into the tubular member 90a that is approximately the same as that inside the fluid pipe 2, the air release valve (not shown) is closed after confirming that the air inside the tubular member 90a has been released. Next, with the inside of the lower case 3 and the inside of the tubular member 90a at approximately the same pressure, the gate valve body 50c is opened, and the drive mechanism 90b of the insertion device 90 is operated to lower the butterfly valve 4.

[0067] As shown in Figure 7, when the butterfly valve 4 enters the interior of the lower case 3, the lower end of the partition wall portion 82 of the butterfly valve 4 is inserted between the guide portions 14, 14, 15, 15, and is guided into the cut portion S1 of the fluid pipe 2.

[0068] The butterfly valve 4 is inserted so that the partition wall portion 82 separates the interior of the lower case 3, and so when the butterfly valve 4 enters the interior of the lower case 3, a load due to the fluid pressure in the fluid pipe 2 is applied to the partition wall portion 82. Therefore, as shown in Figure 9, by fixing the position of the valve body 83 with the water-stopping surface of the valve body 83 inclined at a predetermined angle θ1 (for example, θ1 = 30 degrees) relative to the partition wall portion 82, and inserting the valve body 83 into the interior of the lower case 3 while keeping the opening 86 open and in an effectively open state, the load due to the fluid pressure is less likely to be applied, and the valve body can be inserted in a way that does not obstruct the flow of fluid in the fluid pipe 2.

[0069] In addition, in the butterfly valve 4's effectively open state shown in FIG. 9 , the front and rear ends of the valve element 83 extend in the pipe axial direction beyond the water-stopping surface of the partition wall portion 82, and the cut portion S1 is formed by connecting two perforated portions h1 and h2, each of which is approximately circular in plan view. Therefore, curved recesses, each of which is approximately arc-shaped in plan view, are formed at the front and rear radial ends of the cut end surface of the fluid pipe 2, ensuring space for accommodating the front and rear ends of the valve element 83. Therefore, while the butterfly valve 4 is in its effectively open state, the valve element 83 can be inserted into the cut portion S1 without coming into contact with the cut end surface of the fluid pipe 2. Note that if the effective open state of the valve element 83 cannot be maintained when inserting the butterfly valve 4 due to the flow velocity or water pressure in the existing pipe, an uninterrupted flow rate can be maintained by establishing upstream and downstream bypasses to communicate with each other.

[0070] Next, the seal 84 at the lower end of the partition wall 82 is pressed against the lower seat 8a, the front and rear seals 84 are pressed against the vertical seat 8b, and the seal 84 of the upper cover 81 is pressed against the inner circumferential surface of the upper seat 8c. In this way, when the butterfly valve 4 is installed in a predetermined installation position, the upper opening of the lower case 3 is hermetically closed by the upper cover 81, and the partition wall 82 is installed at the cut portion S1 of the fluid pipe 2, and the interior of the lower case 3 is partitioned by the partition wall 82.

[0071] After the butterfly valve 4 has been installed in the predetermined installation position, as shown in Figure 8, the multiple fixing pins 28 arranged circumferentially around the main part 5 are advanced inward of the main part 5 and engaged with the outer circumferential surface of the upper cover part 81. By engaging the upper cover part 81 with the fixing pins 28, the upward movement of the upper cover part 81 is restricted and the upper cover part 81 is held in the predetermined installation position, preventing the butterfly valve 4 from coming out of the lower case 3.

[0072] Thereafter, the air vent valve (not shown) provided on the cylindrical member 90a is opened, and it is confirmed that the packing (not shown) of the butterfly valve 4 is watertight, and then the insertion device 90 and the gate valve device 50 are removed from the lower case 3. This completes the installation process of the butterfly valve 4.

[0073] In addition, in this embodiment, the first punching step of forming the punched portion h1 is performed using the cutter 72A with a large outer diameter, and then the second punching step of forming the punched portion h2 is performed using the cutter 72B with a small outer diameter. However, the present invention is not limited to this. The order of performing the first and second punching steps is not limited to the first punching step first, as in the above embodiment. The second punching step may be performed first and the first punching step may be performed later. In other words, even if the second punching step of forming the punched portion h2 is performed using the cutter 72B with a small outer diameter as shown in Fig. 10, and then the first punching step of forming the punched portion h1 is performed using the cutter 72A with a large outer diameter as shown in Fig. 11, it is possible to form the cut portion S1 similar to that of the embodiment as shown in Fig. 12.

[0074] [Actions and Effects] As described above, the method for cutting a fluid pipe as an embodiment of the present invention is a method for cutting a fluid pipe by moving cutters 72A, 72B as punching tools that can rotate around an advance / retract shaft 73a downward within a case body 20 that is hermetically attached to the outer peripheral surface of the fluid pipe 2, and by providing a plurality of punching sections h1, h2 in series on the outer peripheral surface of the fluid pipe 2, and comprises at least a first punching step in which cutter 72A as a first punching tool is used to form punching section h1 on the outer peripheral surface of the fluid pipe 2, and a second punching step in which cutter 72B as a second punching tool that is a different type from cutter 72A is used to form punching section h2 on the outer peripheral surface of the fluid pipe 2.

[0075] According to this, by using cutters 72A, 72B having different outer diameter dimensions to serially form multiple perforation sections h1, h2 on the outer peripheral surface of the fluid pipe 2, the shape of the cutting section S1 consisting of perforation sections h1, h2 on the outer peripheral surface of the fluid pipe 2 can be formed with a high degree of freedom, regardless of the shape of each cutter 72A, 72B, while maintaining the structural strength of the fluid pipe 2 after perforation.

[0076] Furthermore, in the first drilling step of forming the perforation portion h1, a cylindrical cutter 72A that is larger than the radial dimension La1 of the fluid pipe 2 and smaller than the outer diameter dimension L1 of the fluid pipe 2 is used as the first drilling tool, and in the second drilling step of forming the perforation portion h2, a cylindrical cutter 72B that is smaller than the radial dimension La of the fluid pipe 2 is used as the second drilling tool, so that the cutting portion S1 consisting of the perforation portions h1 and h2 can be formed with a high degree of freedom using the large perforation portion h1 and the small perforation portion h2.

[0077] Specifically, by forming the perforated portion h1 large using the large-diameter cutter 72A and forming the perforated portion h2 small using the small-diameter cutter 72B, it is possible to maintain the left-right opening dimensions L21, L22, and L23 of the cutting portion S1 at a certain size or greater while making the cutter 72B as small as possible, thereby reducing costs and maintaining the structural strength of the cut fluid pipe 2. Furthermore, compared to a process in which a cylindrical cutter larger than the radius dimension La1 of the fluid pipe 2 and smaller than the outer diameter dimension L1 of the fluid pipe 2 is used twice, the cutting allowance is smaller, the amount of chips is smaller, and the cutting time is shorter.

[0078] Furthermore, depending on the outer diameter dimension L1 of the existing fluid pipe 2, two types of cutters 72A, 72B with different outer diameter dimensions L11, L12 can be used to connect different sized perforation sections h1, h2. For example, when the structural strength of the fluid pipe 2 is high without any perforation sections formed, a large cutter can be used to form the first perforation section in the first perforation step, while a small cutter can be used to form the second perforation section in the second perforation step, which is performed when the strength has decreased due to the formation of the first perforation section. Therefore, perforation sections of a size corresponding to the structural strength of the fluid pipe 2 can be formed compared to when a cut section is formed by connecting two perforation sections using a common cutter.

[0079] Furthermore, curved recesses that are approximately arc-shaped when viewed in a plane are formed at the front and rear of the cut end surface of the fluid pipe 2 in the radial direction, so that a butterfly valve 4 as an opening / closing valve having a partition wall portion 82 arranged to separate the interior of the case body 20 and a valve body 83 rotatably arranged relative to the partition wall portion 82 and opening and closing the interior of the partition wall portion 82 can be inserted into the cut portion S1 of the fluid pipe 2 formed inside the case body 20 in an effective open state in which the valve body 83 is inclined relative to the partition wall portion 82 and with the valve body 83 spaced apart from the cut end surface of the fluid pipe 2, thereby allowing the butterfly valve 4 to be inserted without interfering with the cut end surface of the fluid pipe 2 while maintaining an uninterrupted flow of the fluid inside the fluid pipe 2.

[0080] Furthermore, at least one of the first drilling tool and the second drilling tool is a cylindrical cutter 72A, 72B consisting of a center drill 72b and a hole saw 72a, and the method further includes a step of fixing guide materials 41, 42, 45, 46 having flat surfaces that can be penetrated by the center drill 72b or the hole saw 72a to the outer surface of the fluid pipe 2 so that the flat surfaces are approximately perpendicular to the movement direction of the cutters 72A, 72B, thereby suppressing axial wobble of the hole saw 72a.

[0081] Next, modified examples of the present invention will be described with reference to Figures 13 to 17. Note that in the following modified examples 1 to 3, the perforated portion is formed using a cutter made of a hole saw as an example of a perforating tool, which is substantially the same as the above-described embodiment, and therefore in modified examples 1 and 2, illustrations showing the details of the perforation by the cutter will be omitted, and only plan views showing the formed perforated portion will be used to describe the modified method of cutting a fluid pipe, while in modified example 3, plan views showing the formed perforated portion will be omitted and the modified method of cutting a fluid pipe will be described.

[0082] [Variation 1] A method for cutting a fluid pipe according to a first modification of the present invention will be described with reference to Figures 13 to 15. In the above embodiment, a first drilling step is performed using a cutter 72A made of a hole saw 72a having an outer diameter L11 larger than the radius La1 of the fluid pipe 2 but smaller than the outer diameter L1 of the fluid pipe 2 to form a drilled portion h1 at a first drilling position T11 offset forward from the pipe axis T1 on the outer surface of the fluid pipe 2, and a second drilling step is performed using a cutter 72B made of a hole saw 72a having an outer diameter L12 smaller than the radius La1 of the fluid pipe 2 to form a single drilled portion h2 communicating with the drilled portion h1 at a second drilling position T12 offset rearward from the pipe axis T1 on the outer surface of the fluid pipe 2. However, the second drilling step using cutter 72B may be performed repeatedly to form a plurality of drilled portions communicating with the drilled portion h1.

[0083] Specifically, in this variant example 1, as shown in Figure 13(a), a first drilling step is performed using cutter 72A to form a drilling section h1 at a first drilling position T11 that is offset forward from the pipe axis T1 on the outer surface of the fluid pipe 2, and then, as shown in Figure 13(b), cutter 72B is used to form drilling sections h2, h2 that communicate with the drilling section h1 at second drilling positions T12, T13 that are offset rearward from the pipe axis T1 on the outer surface of the fluid pipe 2 and are each offset in the pipe axis direction from the first drilling position T11, thereby forming a cut section S2 that is wider on the rear side than the cut section S1, as shown in Figure 13(c).

[0084] 13(a), it is preferable to fix by welding guide members 45, 46, with which the cutting blade 72d of the hole saw 72a comes into contact, to the connecting portion between the drilling portion h1 and the drilling portions h2, h2. In this way, the circumferential direction of the cutting blade 72d at the lower end of the hole saw 72a is supported at a single point relative to the corner of the cut edge of the drilling portion h1 when cutting begins. This makes it easy for the cutting position to shift due to axial runout of the hole saw 72a or slippage in the direction of the inclination of the outer peripheral surface of the fluid pipe 2. However, by fixing the guide members 45, 46, the circumferential direction of the cutting blade 72d at the lower end is supported by contact with the upper surfaces of the guide members 45, 46, making it less likely to shift from the predetermined cutting position, and allowing the cutting blade 72d to bite into the outer peripheral surface of the fluid pipe 2.

[0085] Furthermore, the second drilling positions T12, T13 are set at positions that are offset radially (rearward) from the first drilling position T11 and offset in the pipe axial direction (left-right direction), so that the drilled portions h1, h2, h2 are in communication with each other. Furthermore, by repeating the second drilling step using cutter 72B twice to connect multiple drilled portions h2, h2, it is possible to set the opening left-right dimensions L22, L23 larger, as shown in Figure 13(c).

[0086] 14, when installing the butterfly valve 4 in the cutout section S2 inside the lower case 3, the water-stopping surface of the valve body 83 is inclined at a predetermined angle θ2 (for example, θ2 = 45 degrees) relative to the partition wall section 82 to fix the position of the valve body 83, and the butterfly valve 4 can be inserted into the cutout section S2 while keeping the opening 86 in an effectively open state. Furthermore, because the predetermined angle θ2 can be set larger than the predetermined angle θ1 in the above embodiment, the partition wall section 82 is less likely to be loaded by fluid pressure, and the butterfly valve 4 can be inserted more smoothly without impeding the flow of fluid in the fluid pipe 2.

[0087] Furthermore, in this variant example 1, an example has been given of a form in which a first drilling step is performed to form a perforation portion h1 using a cutter 72A with a large outer diameter, and then a second drilling step is performed multiple times to form perforations h2, h2 using a cutter 72B with a small outer diameter, thereby forming a cut portion S2. However, the present invention is not limited to this, and as shown in Figures 15(a) and (b), a second drilling step to form perforations h2, h2 is performed multiple times using a cutter 72B with a small outer diameter, and then a first drilling step to form a perforation portion h1 using a cutter 72A with a large outer diameter is performed to form a cut portion S2, as shown in Figure 15(c).

[0088] That is, the order of execution of the first punching step and the multiple second punching steps is not limited to the first punching step first, second punching step as in the above embodiment, and the second punching step may be executed multiple times first, followed by the first punching step. Furthermore, the second punching step may be executed once, followed by the first punching step, and then the second punching step may be executed a second time. Furthermore, the second punching step is not limited to being executed twice, and may be executed three or more times.

[0089] In this way, by performing the second drilling process to form the drilling section h2 multiple times and arranging multiple drilling sections h2, h2 in succession in the tube axis direction, it is possible to ensure large left and right dimensions L22, L23 of the opening in the tube axis direction without using a cutter with a large outer diameter.

[0090] [Variation 2] Next, a method for cutting a fluid pipe according to a second modification of the present invention will be described with reference to FIGS. 16(a) and 16(b).

[0091] In this second modification, as shown in FIG. 16(a), a first drilling step is performed using a cutter 72C (not shown) made of a hole saw 72a having an outer diameter L12 smaller than the radial dimension La1 of the fluid pipe 2 to form a drilling portion h11 as a first drilling portion at a drilling position approximately vertically above the pipe axis T1 on the outer surface of the fluid pipe 2, and then a second drilling step is performed using a cutter 72D (not shown) made of a hole saw 72a having an outer diameter L11 larger than the radial dimension La1 of the fluid pipe 2 but smaller than the outer diameter L1 to form a drilling portion h12 as a second drilling portion at a drilling position offset forward from the pipe axis T1 on the outer surface of the fluid pipe 2, and a second drilling step is further performed to form a drilling portion h12 as the second drilling portion at a drilling position offset rearward from the pipe axis T1 on the outer surface of the fluid pipe 2, thereby forming a cut portion S3.

[0092] Furthermore, by arranging the front and rear perforation portions h12, h12 opposite each other with the perforation portion h11 at the center and displacing the front and rear perforation portions h12, h12 in the pipe axial direction relative to the perforation portion h11, it is possible to form a cut portion S3 in which the three perforation portions h11, h12, h12 are connected in a direction inclined relative to the radial direction. This makes it possible to increase the predetermined angle θ of the water stopping surface of the valve body 83 relative to the partition wall portion 82 without increasing the size of the cutter 72D as the second perforation tool used in the second perforation step.

[0093] 16(b), a first drilling step may be performed using a cutter 72E (not shown) made of a hole saw 72a having an outer diameter L11 larger than the radius La1 of the fluid pipe 2 and smaller than the outer diameter L1 to form a drilling portion h21 as a first drilling portion at a drilling position approximately vertically above the pipe axis T1 on the outer surface of the fluid pipe 2, followed by a second drilling step using a cutter 72F (not shown) made of a hole saw 72a having an outer diameter L12 smaller than the radius La1 of the fluid pipe 2 to form a drilling portion h22 as a second drilling portion at a drilling position offset forward from the pipe axis T1 on the outer surface of the fluid pipe 2, and a further second drilling step may be performed to form a drilling portion h22 as the second drilling portion at a drilling position offset rearward from the pipe axis T1 on the outer surface of the fluid pipe 2, thereby forming a cut portion S4.

[0094] This allows the cutter 72F used as the second punching tool when performing the first punching step to be made smaller, thereby making it possible to insert the butterfly valve 4 in an effectively open state while minimizing the reduction in structural strength of the fluid pipe 2 after cutting.

[0095] In this way, by using cutters 72C and 72E as a first drilling step to form drilling sections h11 and h21 as first drilling sections at approximately the radial center position on the outer surface of the fluid pipe 2, and by using cutters 72D and 72F to form drilling sections h12, h22 and h22 as second drilling sections connected to drilling sections h11 and h21 at both radial positions on the outer surface of the fluid pipe 2, it is possible to form cutting sections S3 and S4 by connecting multiple drilling sections.

[0096] [Variation 3] Next, a method for cutting a fluid pipe according to a third modification of the present invention will be described with reference to FIGS. 17(a) and 17(b).

[0097] In the above embodiment, an example is given of a form in which the outer surface of the fluid pipe 2 is drilled using cutters 72A and 72B in which the lower end of the center drill 72b does not protrude below the lower end of the hole saw 72a, but the present invention is not limited to this, and the outer surface of the fluid pipe 2 may also be drilled using a cutter 72G having a center drill 172b in which the lower end protrudes below the lower end of the hole saw 72a.

[0098] In this case, when the fluid pipe 2 is cut, the lower end of the center drill 172b penetrates the lower part of the drilled portion formation region on the outer surface of the fluid pipe 2. However, as the drilled portion formation region becomes unstable as it is cut off, axial wobble of the center drill 172b is likely to occur. Therefore, as shown in Figure 17(a), before attaching the lower case 3 to the outer surface of the fluid pipe 2, an on-off valve 62 is hermetically connected to the lower part of the outer surface of the fluid pipe 2 at the position where the lower end of the center drill 172b penetrates, and a drilling device 60 is hermetically connected below the on-off valve 62, and a lower drilled portion 61 is formed by the drilling device 60. After the lower drilled portion 61 is formed, the drilling device 60 is removed, leaving the on-off valve 62.

[0099] 17(b), even if the cutting progresses and the hole formation region on the outer surface of the fluid pipe 2 becomes unstable, the center drill 172b is inserted into the lower drilling section 61 without drilling the outer surface of the fluid pipe 2, thereby preventing axial wobble caused by the center drill 172b drilling the hole formation region. The on-off valve 62 can be collected together with the cut pieces.

[0100] Furthermore, in the embodiment shown in Figures 1 to 12 and variants 1 and 2 shown in Figures 13 to 16, the perforation portion may be formed using a cutter (not shown) having a center drill that protrudes below the lower end of the hole saw, such as cutter 72G in variant 3.

[0101] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0102] For example, in the above-described embodiment and modified example, cutters 72A-72F having hole saw 72a rotatable about advance / retract shaft 73a are used as an example of a drilling tool rotatable about a rotation axis, but the present invention is not limited to this and various other drilling tools such as end mills and drills can be used. In other words, the first drilling tool and the second drilling tool that is different in type from the first drilling tool may be drilling tools of different types, such as a hole saw and an end mill.

[0103] In the above embodiment and modified example, cutters 72A, 72C, 72E as the first punching tool and cutters 72B, 72D, 72F as the second punching tool are the same type of hole saw cutter, but have different outer diameters, i.e., sizes. However, the present invention is not limited to this, and the first punching tool and the second punching tool may differ in at least one of a number of aspects, such as size (outer diameter, inner diameter, vertical dimension), shape, or cutting blade shape. Note that cutters 72A to 72F do not necessarily have to have center drill 72b as long as they have at least hole saw 72a.

[0104] In addition, in the above example, a cutter 72A consisting of a hole saw 72a having an outer diameter L11 larger than the radial dimension La1 of the fluid pipe 2 and smaller than the outer diameter dimension L1 is used as the first drilling tool used in the first drilling step to form the drilling portion h1 as the first drilling portion, and a cutter 72B consisting of a hole saw 72a having an outer diameter L12 smaller than the radial dimension La1 of the fluid pipe 2 is used as the second drilling tool used in the second drilling step to form the drilling portion h2 as the second drilling portion, but the present invention is not limited to this, and the first drilling tool may be smaller than the second drilling tool.

[0105] In addition, in the above-described modified examples 1 and 2, an embodiment has been exemplified in which one first perforation portion is formed in the first perforation step, and two second perforation portions are formed by repeatedly performing the second perforation step twice, thereby forming a cut portion. However, the present invention is not limited to this, and the cut portion may be formed by repeatedly performing the second perforation step two or more times to form two or more second perforation portions. Furthermore, the cut portion may be formed by performing the first perforation step multiple times to form multiple first perforation portions, and performing the second perforation step once to form one second perforation portion. Furthermore, the cut portion may be formed by performing each of the first perforation step and the second perforation step multiple times to form multiple first perforation portions and multiple second perforation portions.

[0106] In the above-described embodiment and modified example, a form in which the first perforation step is performed to form the first perforated portion and the second perforation step is performed to form the second perforated portion, thereby forming the cut portion, is exemplified, but the present invention is not limited to this, and in addition to the first perforation step and the second perforation step, a third perforation step may be performed using a separate perforation tool different from the first perforation tool and the second perforation tool to form the perforated portion and then cut. Note that the perforation step may include three or more perforation steps.

[0107] In addition, in the above embodiment, an example is given in which a predetermined portion of the fluid pipe 2 is cut by the cutting device 1 to form the cut section S1 in order to install a butterfly valve 4 at the predetermined portion of the fluid pipe 2, but the present invention is not limited to this, and may be used as a method of cutting a predetermined portion of the fluid pipe 2 by the cutting device 1 regardless of whether or not a butterfly valve 4 is installed at the cut section S1.

[0108] Furthermore, in the above embodiment, a form in which a butterfly valve 4 is installed at the cut portion of the fluid pipe 2 is exemplified, but the present invention is not limited to this, and as long as it is a fluid control valve that can control the flow of fluid, it is not limited to the butterfly valve 4, and may be a valve body such as a plug (stop valve), a gate valve that can open and close a flow path, or a switching valve. [Explanation of symbols]

[0109] 1 cutting device 2 Fluid tube 2b rear end 2c,2d intercept 2f front end 3 Lower case (case body) 4 Butterfly valve (on-off valve) 20 Case body 41 Guide material 41c Top surface (flat surface) 42 Guide material 42c Top surface (flat surface) 45,46 Guide material 50 Gate valve device 50a Valve box (case body) 50b Valve cover (case body) 50c Gate valve body 60 Drilling device 61 Lower perforation 62 On-off valve 70 Drive mechanism 72A, 72C, 72E Cutter (first punch) 72B, 72D, 72F Cutter (second punch) 72a Hole saw (perforating tool) 72b Center drill (drilling tool) 72d cutting blade 73a Advance / retreat shaft (rotation shaft) 74A, 74B Cover member 81 Top lid 82 Partition wall 83 Valve body 86 Aperture 90 Insertion Device 172b Center drill (drilling tool) S1~S4 cutting section h1,h11,h21 Perforation part (1st perforation part) h2, h12, h22 perforation part (second perforation part)

Claims

1. A method for cutting a fluid pipe, comprising: moving a rotatable punching tool around a rotation axis within a case body that is hermetically attached to an outer surface of the fluid pipe, thereby cutting the fluid pipe by forming a plurality of punching portions in series on the outer surface of the fluid pipe, forming a first perforated portion on an outer surface of the fluid pipe using a first perforating tool; a step of forming a second perforation portion on the outer surface of the fluid pipe using a second perforation tool of a different type from the first perforation tool.

2. In the step of forming the first piercing portion, a cylindrical cutter having a diameter larger than the radius of the fluid pipe and smaller than the diameter of the fluid pipe is used as the first piercing tool, 2. The method for cutting a fluid pipe according to claim 1, wherein in the step of forming the second perforated portion, a cylindrical cutter having a radius smaller than that of the fluid pipe is used as the second perforation tool.

3. 2. The method for cutting a fluid pipe according to claim 1, wherein the step of forming the second perforated portion is carried out a plurality of times, and a plurality of the second perforated portions are provided in series in the axial direction of the pipe.

4. forming the first perforation portion at a substantially central position in the radial direction on the outer surface of the fluid pipe using the first perforation tool; 2. The method for cutting a fluid pipe according to claim 1, further comprising the step of using the second piercing tool to form the second piercing sections connected to the first piercing section at both radial positions on the outer surface of the fluid pipe.

5. 2. The method for cutting a fluid pipe according to claim 1, further comprising inserting an on-off valve having a partition wall portion arranged to separate the interior of the case body and a valve body rotatably mounted relative to the partition wall portion for opening and closing the interior of the partition wall portion into the cutting portion of the fluid pipe formed inside the case body, with the valve body inclined relative to the partition wall portion in an effective open state and spaced apart from the cutting portion of the fluid pipe.

6. At least one of the first punching tool and the second punching tool is a cylindrical cutter including a center drill and a hole saw, 2. The method for cutting a fluid pipe according to claim 1, further comprising a step of fixing a guide material having a flat surface that can be penetrated by the center drill or the hole saw to the outer surface of the fluid pipe so that the flat surface is approximately perpendicular to the direction of movement of the cutter.

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