Branch pipe formation device and drilling method for existing pipe

Abstract

To provide a branch pipe formation device and a drilling method for an existing pipe capable of preventing axial center deviation of a cutter from the existing pipe while suppressing increase in sizes of the cutter and the branch pipe formation device.SOLUTION: A branch pipe formation device 100 includes a case part 1 fitted to an outer surface of an existing pipe W in an uninterrupted flow state and a drilling machine 3 that forms a drilled hole on a part of the existing pipe W. The case part 1 includes a branch part 14 capable of communicating with the drilled hole. The drilling machine 3 includes: a cylindrical cutter 32 supported by the case part 1 so as to enable reciprocation in the state of rotating about a cutter axial center WZ; and a center drill 40 projecting from a rotation center position of the cutter 32 to a lower side of the cutter 32 and having a shaft part 41 rotating about the cutter axial center WZ. Viewed in a direction along the cutter axial center WZ, the cutter axial center WZ is disposed at a position that is deviated from a pipe axial center WX of the existing pipe W and that is overlapped with the existing pipe W. The center drill 40 has a cutting part 42 formed at a tip of the shaft part 41 and including a cutting surface with a flat blade edge shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a branch pipe forming device and a method for drilling holes in an existing pipe. [Background technology]

[0002] For example, Patent Document 1 shows a technology for a branch pipe forming device that can form a perforation hole in an existing pipe while attached to the outer surface of an existing pipe in an uninterrupted state, and then send the fluid from the perforation hole thus formed into a branch pipe.

[0003] Patent Document 1 describes a branch pipe forming device equipped with a drilling machine that forms a drilled hole in a portion of an existing pipe in an uninterrupted flow state. The drilling machine has a cylindrical cutter that is supported so as to be freely reciprocated while being driven to rotate around the cutter axis, and when viewed in a direction along the cutter axis, the cutter axis is positioned so that it overlaps with the existing pipe but is offset from the pipe axis of the existing pipe. Therefore, even if a small-diameter cutter is used, a drilled hole with the required opening area can be formed in the existing pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-35872 Summary of the Invention [Problem to be solved by the invention]

[0005] When forming a drilling hole in a small-diameter existing pipe using the branch pipe forming device of Patent Document 1, the smaller the diameter of the existing pipe, the smaller the contact area between the cutting surface of the cutter and the existing pipe, so the cutter cannot withstand the reaction force acting from the existing pipe, and there is a risk that the axis of the cutter will shift from the drilling position.

[0006] Therefore, there is a need for a branch pipe forming device and a method for drilling holes in an existing pipe that can prevent the cutter and branch pipe forming device from becoming misaligned with respect to the existing pipe while suppressing an increase in size. [Means for solving the problem]

[0007] The branch pipe forming device of the present invention is characterized by the following features: a case portion that is attached to the outer surface of an existing pipe in an uninterrupted flow state; and a drilling machine that forms a drilling opening in a part of the existing pipe, the case portion having a branch portion that can communicate with the drilling opening; the drilling machine comprising: a cylindrical cutter supported on the case portion so as to be freely operable to reciprocate while rotating around a cutter axis; and a center drill having a shank that protrudes below the cutter from the center of rotation of the cutter and rotates around the cutter axis; when viewed in a direction along the cutter axis, the cutter axis is positioned at a position that is offset from the pipe axis of the existing pipe and overlaps with the existing pipe; and the center drill has a cutting portion formed at the tip of the shank and has a cutting edge that includes a flat cutting surface.

[0008] According to this characteristic configuration, when viewed along the cutter axis, the cutter axis is positioned offset from the axis of the existing pipe and overlaps with the existing pipe. This allows for a smaller cutter radius compared to a cutter axis positioned outside the outer surface of the existing pipe when viewed along the cutter axis. Furthermore, because the center drill protrudes downward from the cutter's rotation center position and further downward than the cutter, the center drill contacts the existing pipe before the cutter during drilling. Here, if the cutting surface of the center drill is flat, the contact area between the cutting surface and the existing pipe can be increased compared to when the cutting surface is inclined relative to the horizontal plane. This increases the resistance at the contact surface between the existing pipe and the cutting surface, thereby preventing misalignment of the center drill relative to the existing pipe. Furthermore, the position of the drilling machine relative to the existing pipe is fixed by the center drill, preventing misalignment of the cutter axis. Thus, a branch pipe forming device has been constructed that can efficiently perform drilling operations by preventing misalignment of the cutter axis relative to the existing pipe while minimizing the size of the cutter and branch pipe forming device.

[0009] In addition, since the resistance between the existing pipe and the cutting surface is increased, the rotation speed of the center drill and cutter is reduced compared to conventional methods, which makes it possible to prevent cracks in the existing pipe caused by rapid cutting during drilling operations.

[0010] In addition to the above configuration, the cutting portion may be rectangular when viewed in a direction along the cutter axis, and the cutting surface may be formed on a pair of edges that are point-symmetrical with respect to the cutter axis.

[0011] This allows the cutting surface to be formed on a pair of edges that are point-symmetrical with respect to the cutter axis, so that when the center drill comes into contact with the existing pipe, the cutting surface can be brought into contact with the surface of the existing pipe first. This fixes the position of the center drill relative to the existing pipe, thereby preventing the cutter from misaligning.

[0012] In addition to the above configuration, the cutting portion may have an inclined surface that slopes upward from the cutting surface toward the edge opposite to the edge on which the cutting surface is formed, and the cutting surface and the inclined surface may be arranged point-symmetrically with respect to the cutter axis.

[0013] This allows chips and other debris cut from the cutting surface to be removed from the cutting section along the inclined surface, preventing chips and other debris from getting between the cutting surface and the existing pipe, allowing drilling work to be carried out efficiently.

[0014] In addition to the above configuration, the shaft portion may have a recess formed on the side surface of the shaft portion and having a bottom surface that slopes downward in the direction of rotation of the shaft portion, and a movable member having one end fixed to the bottom surface and another end opposite the one end that is movable along the bottom surface, and the movable member may be switchable between a first state in which the other end protrudes radially outward from the shaft portion, and a second state in which the entire movable member is accommodated in the recess as the shaft portion rotates.

[0015] According to this, during the drilling operation, as the shank of the center drill rotates, the entire movable member enters the second state, where it is housed in the recess. This prevents contact between the movable member and the existing pipe, and the drilling operation is not obstructed by the movable member. Then, at the end of the drilling operation, the rotation of the shank stops, and the other end of the movable member enters the first state, where it protrudes radially outward from the shank due to its own weight. This causes the cut portion separated from the existing pipe by the drilling operation to come into contact with the other end of the movable member. As a result, by removing the drill from the case with the cut portion supported by the other end of the movable member, it is possible to remove the cut portion from the existing pipe.

[0016] In addition to the above configuration, the movable member may have a triangular cross section whose width narrows from the one end to the other end, and a first side surface on the upstream side of the rotation direction may be a flat surface with sharp corners, and a second side surface on the downstream side of the rotation direction may be a flat surface with chamfered corners.

[0017] As the shaft rotates, an inertial force acts on the movable member in the direction opposite to the rotational direction. Therefore, because the first side surface on the upstream side of the rotational direction is a flat surface with sharp corners, the flat surface is likely to come into contact with the recess, making it easier for the movable member, which is subjected to the inertial force in the direction opposite to the rotational direction, to enter the second state. Furthermore, because the second side surface on the downstream side of the rotational direction is a flat surface with chamfered corners, it is possible to increase the contact area between the other end of the movable member protruding radially outward from the shaft in the first state and the cut portion, allowing for smooth collection of the cut portion.

[0018] The characteristic configuration of the method for drilling holes in an existing pipe using any of the above-mentioned branch pipe forming devices according to the present invention is that it comprises an attachment process in which the case portion is attached in close contact with the outer surface of the existing pipe, and a drilling process in which the cutter and the center drill are used to form the drilling hole in the existing pipe.

[0019] According to this, when viewed in a direction along the cutter axis, the cutter axis is positioned at a position offset from the axis of the existing pipe and overlaps with the existing pipe. This allows the cutter radius to be smaller than when the cutter axis is positioned outside the outer surface of the existing pipe when viewed in a direction along the cutter axis. Furthermore, because the center drill protrudes downward from the center of rotation of the cutter further than the cutter, the center drill contacts the existing pipe before the cutter during the drilling process. Here, the flat cutting surface of the center drill increases the contact area between the cutting surface and the existing pipe, allowing for increased resistance at these contact surfaces. This suppresses misalignment of the center drill relative to the existing pipe, thereby preventing misalignment of the cutter. Thus, a branch pipe forming device has been constructed that can efficiently perform drilling operations by preventing misalignment of the cutter relative to small-diameter existing pipes while suppressing the size of the cutter and branch pipe forming device.

[0020] Furthermore, the characteristic configuration of the method for drilling holes in an existing pipe according to the present invention comprises an attachment process in which the case portion is attached in close contact with the outer surface of the existing pipe, a drilling process in which the cutter and the center drill are used to form the drilling hole in the existing pipe, and a recovery process in which, after the drilling process, the cutter and the center drill are pulled up and the cut portion of the existing pipe is recovered, wherein in the drilling process, the movable member is in the second state when it comes into contact with the existing pipe, and in the recovery process, the other end of the movable member, which is in the first state, abuts against the cut portion.

[0021] According to this, during the drilling step, as the shank of the center drill rotates, the movable member enters the second state, where the entire movable member is housed in the recess. This prevents contact between the movable member and the existing pipe, and the drilling operation is not interfered with by the movable member. Then, during the recovery step, the rotation of the shank stops, and the other end of the movable member enters the first state, where it protrudes radially outward from the shank due to its own weight. This causes the cut portion separated from the existing pipe by the drilling operation to come into contact with the other end of the movable member. In this way, by removing the drilling machine from the drilling position while the cut portion is held by the other end of the movable member, it is possible to remove the cut portion from the existing pipe. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of the branch pipe forming device in which the cutter and the center drill are in their initial positions. [Figure 2] 1A and 1B are a front view and a side view of a center drill. [Figure 3] FIG. 2 is a perspective view of the tip of a center drill. [Figure 4] 3A and 3B are a front view, a plan view, and a side view of a cutting part. [Figure 5] FIG. 4 is a perspective view showing the vicinity of a recess in a shaft portion. [Figure 6] 4A and 4B are explanatory diagrams showing a first state and a second state of a movable member; [Figure 7] 10 is a cross-sectional view of a branch pipe forming device in a position where a center drill contacts a fluid pipe. FIG. [Figure 8] 10A and 10B are diagrams showing the state of the movable member during the drilling process. [Figure 9] 10 is a cross-sectional view of the branch pipe forming device after the drilling process is completed and the cutter and center drill have reached the end position of the drilling operation. FIG. [Figure 10] 10 is a cross-sectional view of the branch pipe forming device in a state where the cutter has returned. FIG. [Figure 11] 10A and 10B are diagrams showing the state of the movable member after a drilling step. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Basic configuration] As shown in Figure 1, the branch pipe forming device 100 is equipped with a case 1 configured as a split T-pipe that is attached to the outer surface of a fluid pipe W (an example of an existing pipe) and that can send water from a branch section 14, an operation valve 2 that is arranged in a sealed state on top of the case 1 and that can open and close an opening 13H of the case 1, and a drilling machine 3 that is also arranged in a sealed state on top of the operation valve 2. This branch pipe forming device 100 allows the drilling machine 3 to form a drilling opening Wa (see Figure 10) in a part of the fluid pipe W (existing pipe) when fluid is flowing uninterrupted, thereby enabling construction to send the fluid flowing in the fluid pipe W to the branch section 14.

[0024] Hereinafter, the horizontal direction in which the fluid pipe W extends (the direction along the pipe axis WX of the fluid pipe W) will be referred to as the "X direction." The horizontal direction perpendicular to the X direction and in which the branching section 14 extends (the direction along the branching axis WY of the branching section 14) will be referred to as the "Y direction," and the direction perpendicular to the X and Y directions (the vertical direction) will be referred to as the "Z direction." The upstream side in the Y direction will also be referred to as the "upstream side Y1," and the downstream side will also be referred to as the "downstream side Y2." Furthermore, the vertically upper side in the Z direction will also be referred to as the "upper side Z1," and the vertically lower side will also be referred to as the "lower side Z2."

[0025] [Case] The case 1 has a first divided member 11 arranged on the upper side Z1 of the fluid pipe W, a second divided member 12 arranged on the lower side Z2 of the fluid pipe W, and a branch portion 14 held in a state sandwiched between the first divided member 11 and the second divided member 12. The first divided member 11, the second divided member 12, and the branch portion 14 are cast from, for example, ductile cast iron. The branch portion 14 is generally cylindrical. A flange protruding radially outward from the outer circumferential surface of the branch portion 14 may be formed on the Y2 side of the branch portion 14, and this flange may be connected to another fluid pipe or the like.

[0026] The first divided member 11 and the second divided member 12 have a cut surface that is aligned along a plane that includes the pipe axis WX of the fluid pipe W and the branch axis WY of the branch portion 14, and are connected to each other in a sealed state. Here, "a cut surface that is aligned along a plane that includes the pipe axis WX of the fluid pipe W and the branch axis WY of the branch portion 14" means that the cut surface is on a plane that includes the pipe axis WX of the fluid pipe W and the branch axis WY of the branch portion 14, or on a plane that is approximately parallel to that plane.

[0027] The first divided member 11 is formed in a semicircular shape that covers the upper part of the outer periphery of the fluid pipe W, and has a semicircular first end opening 11a that covers the upper part of the fluid pipe W at its end along the pipe axis WX, and a semicircular first branch opening 11b that covers the upper part of the branch portion 14. In addition, a cylindrical extension portion 13 that extends toward the upper side Z1 is formed on the upper surface of this first divided member 11, coaxial with the cutter axis WZ of the cutter 32 described above.

[0028] Similarly, the second divided member 12 is formed in a semicircular shape that covers the lower part of the outer periphery of the fluid pipe W, and has a semicircular second end opening 12a at its end along the pipe axis WX that covers the lower part of the fluid pipe W, and a semicircular second branch opening 12b that covers the lower part of the branch part 14. In addition, a notch 121 that prevents contact with the cutting part 42 of a center drill 40 (described later) is formed in the bottom of the second divided member 12, coaxially with the cutter axis WZ.

[0029] These first divided member 11 and second divided member 12 are configured so that their respective split surfaces are aligned and can be integrated to cover the entire circumference of the fluid pipe W, with the first divided member 11 forming a first flange portion 11f along the split surface and the second divided member 12 forming a second flange portion 12f along the split surface.

[0030] When attaching the case 1 to the fluid pipe W, the first divided member 11 and the second divided member 12 are positioned to sandwich the fluid pipe W, the branch portion 14 is positioned to be sandwiched between the first branch opening 11b and the second branch opening 12b, the split surfaces of the respective divided members are aligned, and the first flange portion 11f and the second flange portion 12f are fastened together with a plurality of fasteners B. As a result, the case 1 is attached and fixed to the outer surface of the fluid pipe W, and the branch portion 14 is fixed to the case 1 in a sandwiched state.

[0031] Note that a seal member S may be sandwiched between the inner periphery of the first end opening 11a of the first divided member 11, the inner periphery of the second end opening 12a of the second divided member 12, and the entire outer periphery of the fluid pipe W facing these. Similarly, a seal member S may be sandwiched between the inner periphery of the first branch opening 11b, the inner periphery of the second branch opening 12b, and the outer periphery of the branch portion 14.

[0032] [Work valve] As shown in FIG. 1, the extension portion 13 is a cylindrical member that extends upward Z1 from the top surface of the first divided member 11. At the top of the first divided member 11, the working valve 2 is connected in a sealed state to the extension portion 13, covering the side surface of the extension portion 13. The working valve 2 has a working valve main body 21 that opens and closes the opening 13H of the extension portion 13, and a working valve housing 20 that houses the working valve main body 21 so that it can move horizontally. The working valve housing 20 is attached in close contact with the extension portion 13. The working valve 2 can open and close the opening 13H by moving the working valve main body 21 horizontally between a valve-closing position for the opening 13H and a valve-open position for the opening 13H (see FIGS. 1 and 10).

[0033] A support part 20a for supporting the drill casing 31 of the drill 3 may be provided on the upper part of the work valve casing 20. The support part 20a is arranged coaxially with the cutter axis WZ.

[0034] [Drilling machine] As shown in FIG. 1 , the drilling machine 3 has a drilling machine casing 31, a cylindrical cutter 32, a drive disk 33 that rotates the cutter 32, a drive shaft 34, and a center drill 40. The drilling machine casing 31 is a cylindrical body centered on the cutter axis WZ, and a drilling machine flange portion 31a at the bottom of the drilling machine casing 31 is connected to the support portion 20a of the work valve casing 20, thereby forming a space 31S inside the drilling machine casing 31. The cutter 32, the center drill 40, etc. are accommodated in the space 31S. Furthermore, when the drilling machine casing 31 is assembled to the work valve casing 20, the space 31S, the internal space of the work valve casing 20, and the internal space of the case portion 1 are in a state of communication.

[0035] A drive unit (not shown) for driving the cutter 32 and the center drill 40 may be connected to the upper part of the drill housing 31. The drive unit can rotate the drive shaft 34 in the Z direction. The drive unit may also have a processing unit, such as a microprocessor or a DSP (digital signal processor), that performs control according to a preset program. This processing unit drives the drive shaft 34 to rotate and moves the drive shaft 34 in a direction along the cutter axis WZ, thereby performing a drilling operation in which the cutter 32 and the center drill 40 contact the fluid pipe W to form a drilled hole Wa, and a return operation in which the cutter 32 and the center drill 40 return to the space 31S in the drill housing 31 after the drilling operation. In this way, the cutter 32 and the center drill 40 are supported by the drive shaft 34 so as to be freely reciprocable. The cutter 32 and the center drill 40 are indirectly supported by the case 1 via the drill housing 31 and the work valve 2.

[0036] The cutter 32 is disposed coaxially with the cutter axis WZ, has a cutting edge 32a formed at the end on the lower side Z2, and functions as a hole saw. The end on the upper side Z1 of the cutter 32 is fixedly connected to the drive disk 33. Although not shown in the figure, the cutter 32 has a number of through holes formed in its cylindrical portion.

[0037] The drive disk 33 is fixedly connected to the cutter 32 and has a disk shape coaxial with the cutter axis WZ. Similarly, the drive shaft 34 is also arranged coaxially with the cutter axis WZ and is connected to the drive disk 33.

[0038] A center drill 40 according to this embodiment will be described with reference to FIGS. 2 to 6. As shown in FIGS. 2(a) and 2(b), the center drill 40 has a shank 41 arranged coaxially with the cutter axis WZ and a cutting portion 42 formed at the tip (end on the lower side Z2) of the shank 41. The end on the upper side Z1 of the shank 41 is fixedly connected to the drive disk 33. The drive disk 33 may be formed with a connecting portion to which the end of the shank 41 can be connected. The cutting portion 42 is a member equipped with a carbide tip and detachable from the shank 41, and is fixed to the tip of the shank 41 by the connecting portion 43 and a fixing member 44. The tip of the center drill 40 protrudes downward Z2 beyond the cutting edge 32a of the cutter 32 (see FIG. 1). More specifically, the cutting portion 42 of the center drill 40 is located below Z2 beyond the cutting edge 32a of the cutter 32. Therefore, when the drive shaft 34 is advanced toward the lower side Z2, the center drill 40 comes into contact with the fluid pipe W before the cutter 32 does.

[0039] As shown in FIG. 3, the connecting portion 43 is disposed on the lower Z2 surface of the shaft portion 41 and abuts against both side surfaces 42c of the cutting portion 42, thereby fixing the cutting portion 42 to the lower Z2 surface of the shaft portion 41. The connecting portion 43 is formed integrally with the shaft portion 41 and has a pair of semi-cylindrical shapes. Insertion holes (not shown) are formed on the side surfaces of the connecting portion 43, through which the fixing member 44 can be inserted. The cutting portion 42 is fixed to the lower surface of the shaft portion 41 by the fixing member 44, with both side surfaces 42c of the cutting portion 42 sandwiched between the connecting portions 43 (see FIG. 2(b)).

[0040] As shown in FIGS. 3 and 4, the cutting portion 42 has a substantially rectangular parallelepiped shape. In FIGS. 3 and 4, the cutting portion 42 is shown with the upper side of the paper being the lower side Z2 and the lower side of the paper being the upper side Z1. As shown in FIG. 4(a), an insertion hole 424 through which the fixing member 44 can be inserted is formed in the side surface 42c of the cutting portion 42. Also, as shown in FIG. 4(b), the cutting portion 42 has a rectangular shape when viewed in the direction along the cutter axis WZ, and in this embodiment, is formed as a parallelogram. On the lower side Z2 of the cutting portion 42, cutting surfaces 42a and 42a' with flat cutting edges are formed on the edges (peripheries) of opposing long sides 420 and 421 (examples of sides). A flat cutting edge shape means that the cutting edge is substantially parallel to a plane (horizontal plane) including the X and Y directions. The cutting surface 42a is provided along the long side 420 from the vicinity of the cutter axis WZ toward the short side 422, and the cutting surface 42a' is provided along the long side 421 from the vicinity of the cutter axis WZ toward the short side 423. In other words, the cutting surfaces 42a, 42a' are formed on a pair of edges on the lower side Z2 surface of the cutting part 42 that are point-symmetrical with respect to the cutter axis WZ.

[0041] 4(b) and 4(c), the cutting portion 42 is formed with an inclined surface 42b inclined in the Z1 direction from the cutting surface 42a toward the long side 421, and an inclined surface 42b' inclined in the Z1 direction from the cutting surface 42a' toward the long side 420. Similarly, the inclined surfaces 42b, 42b' are formed on a pair of edges on the lower Z2 surface of the cutting portion 42 that are point-symmetric with respect to the cutter axis WZ.

[0042] In this embodiment, as shown in Fig. 1, when viewed in the Z direction, the cutter axis WZ is positioned at a position offset from the pipe axis WX of the fluid pipe W but overlaps with the fluid pipe W. In other words, when viewed in the Z direction, the cutter axis WZ is positioned inside the outer surface of the fluid pipe W. Furthermore, the perforation radius of the cutter 32 is set so that, when viewed in a direction along the cutter axis WZ, the cutting area by the cutter 32 exceeds the outer periphery of the fluid pipe W (the outer periphery in the direction in which the cutter axis WZ deviates from the pipe axis WX). By setting the positional relationship of the axes and the perforation radius of the cutter 32 in this way, the cut portion Wb (see Fig. 10) cut by the cutter 32 becomes a single member.

[0043] Furthermore, in this embodiment, the cutting portion 42 has cutting surfaces 42a, 42a' with flat cutting edges, so that even if the fluid pipe W has a small diameter, it is possible to increase the contact area between the cutting surfaces 42a, 42a' and the fluid pipe W. This makes it possible to increase the resistance at the contact surface between the fluid pipe W and the cutting surfaces 42a, 42a', suppressing misalignment of the center drill 40 with respect to the fluid pipe W and preventing misalignment of the cutter axis WZ.

[0044] [Cutting part removal mechanism] The center drill 40 is provided with a removal mechanism that removes the cut portion Wb, which has been separated from the fluid pipe W by the drilling action of the cutter 32, together with the return action of the cutter 32. This removal mechanism will be described with reference to Figs. 2 and 5-6.

[0045] 2 and 5, a recess 45 is formed on the outer peripheral surface of the shank 41, in which a movable member 60, described later, is disposed. The recess 45 is provided at a position spaced a distance L from the tip of the lower side Z2 of the shank 41 so as to be located inside the fluid pipe W (see FIG. 9) when the drilling operation is completed and the cutting portion 42 of the center drill 40 is positioned near the notch 121 of the second divided member 12 (when the cutting portion 42 reaches the end position of the drilling operation). It is preferable that the dimension L be smaller than the outer diameter of the fluid pipe W.

[0046] 2(b), two recesses 45 are provided on either side of the cutter axis WZ on the outer circumferential surface of the shaft portion 41. In this embodiment, the recesses 45, 45 are not on the same plane, but they may be on the same plane.

[0047] As shown in FIG. 5, the recess 45 has a substantially triangular pyramid-shaped space and a bottom surface 45a that is inclined downward Z2 from a horizontal plane along the rotation direction P. The bottom surface 45a has a fan-like shape (see FIG. 6). The recess 45 also has a wall surface 45b located upstream of the bottom surface 45a in the rotation direction P and a wall surface 45c located downstream of the bottom surface 45a in the rotation direction P. The wall surface 45b is a surface that is inclined upward Z1 from a horizontal plane along the rotation direction P, and the wall surface 45c is a surface parallel to the Z direction. The dimension of the intersection line between the bottom surface 45a and the wall surface 45b is longer than the dimension of the intersection line between the bottom surface 45a and the wall surface 45c. The shapes of the wall surfaces 45b and 45c in a plan view are fan-shaped, similar to the shape of the bottom surface 45a.

[0048] The bottom surface 45a and the wall surface 45b are provided symmetrically in the Z direction with respect to the intersection line between the bottom surface 45a and the wall surface 45b (see FIG. 2(a)). The bottom surface 45a and the wall surface 45b are inclined at approximately 45° from a horizontal plane including the apex of the approximately triangular pyramid formed by the recess 45 toward the lower side Z2 or the upper side Z1 (see FIG. 2(b)). Therefore, the angle formed by the bottom surface 45a and the wall surface 45b is approximately 90°. The wall surface 45c is a surface parallel to the Z direction, so the angle formed by the bottom surface 45a and the wall surface 45b and the wall surface 45c is approximately 90°.

[0049] The bottom surface 45a may be provided with an insertion hole 45d for inserting a fixing member 64 that fixes the movable member 60 (see FIG. 2(b)). As shown in FIG. 5, the movable member 60 is arranged in the recess 45 such that one end 61 of the movable member 60 is fixed to the bottom surface 45a of the recess 45, and the other end 62 opposite to the one end 61 is movable along the bottom surface 45a. The lower surface of the movable member 60 is arranged to abut against the bottom surface 45a of the recess 45.

[0050] As shown in FIG. 6 , the movable member 60 has a base 66 extending from one end 61 in the first direction A and a narrow portion 67 whose width narrows from the base 66 toward the other end 62. In this embodiment, the one end 61 side of the base 66 is arc-shaped in a plan view, but it may be rectangular. Furthermore, in a plan view of the movable member 60, the narrow portion 67 has a side extending along the first direction A from the end opposite the one end 61 of the base 66 and a side extending from the end in a direction intersecting the first direction A, and the intersection of these sides forms the other end 62. Therefore, the cross-sectional shape of the narrow portion 67 in a plan view is a right triangle. Note that the movable member 60 may not have the base 66 and may have only the narrow portion 67. Furthermore, both sides of the narrow portion 67 in a plan view may extend along a direction intersecting the first direction A and intersect at the other end 62. In this case, the cross-sectional shape of the movable member 60 is triangular.

[0051] The movable member 60 has an insertion hole 65 for inserting a fixing member 64 that fixes one end 61 of the movable member 60 to the bottom surface 45a of the recess 45. In this embodiment, the insertion hole 65 is provided in the base portion 66.

[0052] When the movable member 60 is disposed in the recess 45, the first side surface 60a of the movable member 60 located upstream in the rotation direction P of the shaft portion 41 is a surface where the side surface of the base portion 66 and the side surface of the narrow width portion 67 are continuous. The first side surface 60a is formed as a flat surface with sharp corners (see FIG. 5). The second side surface 60b of the movable member 60 opposite the first side surface 60a is a side surface of the narrow width portion 67 and is located downstream in the rotation direction P of the shaft portion 41. In this embodiment, the edge of the second side surface 60b on the upper surface side of the movable member 60 is chamfered, and a slope 60c is formed between the second side surface 60b and the upper surface of the movable member 60. Note that the corners of the movable member 60 may be rounded except for the first side surface 60a.

[0053] The bottom surface 45a of the recess 45 is inclined downward Z2 with respect to the horizontal plane, and is further inclined downward Z2 along the rotation direction P. Therefore, when the movable member 60 is positioned so that the first side surface 60a of the movable member 60 is located on the wall surface 45b side of the recess 45 and the second side surface 60b of the movable member 60 is located on the wall surface 45c side of the recess 45, the movable member 60 takes a position in which the second side surface 60b is close to the wall surface 45c due to its own weight, and the movable member 60 is in a first state in which the other end 62 of the movable member 60 protrudes outside the recess 45, as shown in FIG.

[0054] In this embodiment, the movable member 60 and the recess 45 constitute a mechanism for extracting the cut portion Wb of the fluid pipe W. That is, when the movable member 60 is in the first state, the other end 62 of the movable member 60, which protrudes radially outward from the shank 41, abuts against the cut portion Wb, allowing the movable member 60 to support the cut portion Wb at this abutment surface (see FIG. 10 ). More specifically, the corner of the inclined surface 60c of the movable member 60 abuts against the cut portion Wb (see FIG. 11 ). The second side surface 60b of the movable member 60 has the inclined surface 60c with a chamfered corner, increasing the contact area with the cut portion Wb. Furthermore, when the drilling operation is completed, the center drill 40 penetrates the cut portion Wb, and the cut portion Wb can maintain a stable posture by contacting the other end 62 of the movable member 60 with the shank 41. Therefore, by pulling up the shaft portion 41 into the space 31S of the drilling machine housing 31 while the cutting portion Wb is supported by the shaft portion 41, the cutting portion Wb can be removed from the case portion 1 without having to perform any additional removal work.

[0055] As described above, only one end 61 of the movable member 60 is fixed to the bottom surface 45a of the recess 45, and the other end 62 is movable along the bottom surface 45a. Therefore, when the center drill 40 rotates and the shank 41 rotates along the rotation direction P, an inertial force acts on the movable member 60 in the direction P' opposite to the rotation direction P. As a result, the other end 62 of the movable member 60 moves toward the direction P' opposite to the rotation direction P, and assumes a position in which the first side surface 60a is close to the wall surface 45b of the recess 45, thereby entering the second state in which the entire movable member 60 is accommodated in the recess 45, as shown in FIG. 6(b). In particular, because the first side surface 60a of the movable member 60 is a flat surface with sharp corners, the first side surface 60a and the wall surface 45b of the recess 45 are likely to come into contact with each other, and the inertial force makes it easy for the movable member 60 to enter the second state.

[0056] Therefore, when the shaft 41 is rotating, i.e., during the drilling operation, the movable member 60 does not protrude outside the recess 45, so the recess 45 does not come into contact with the fluid pipe W. Therefore, even if the movable member 60 is disposed on the shaft 41, the drilling operation can be performed as usual. Furthermore, the first state and the second state of the movable member 60 can be switched depending on whether the shaft 41 is rotating or not, so there is no need for a separate switching operation. In this way, the branch pipe forming device 100 according to this embodiment is highly user-friendly. The movable member 60 is preferably fixed to the bottom surface 45a in a manner that allows it to take the first state and the second state.

[0057] [Method for drilling fluid pipes] Next, a method for drilling a fluid pipe W will be described with reference to Figures 1 and 7 to 11. The method for drilling a fluid pipe W according to this embodiment includes an attachment step of attaching the case 1 to the outer surface of the fluid pipe W in a tight contact state, a drilling step of forming a drilling opening Wa by a drilling operation, and a recovery step of recovering the cut portion Wb of the fluid pipe W.

[0058] First, the installation process for attaching the case 1 to the outer surface of the fluid pipe W in close contact will be described. As shown in FIG. 1 , in the installation process, the second divided member 12 is placed under the outer periphery of the fluid pipe W, the branch portion 14 is placed in a predetermined position, and the first divided member 11 is placed so as to cover the upper portion of the outer periphery of the fluid pipe W. These are then connected with a plurality of fasteners B to install the case 1. At this time, a seal member S may be sandwiched between the inner periphery of the first end opening 11a of the first divided member 11, the inner periphery of the second end opening 12a of the second divided member 12, and the entire outer periphery of the fluid pipe W facing these openings. A seal member S may also be sandwiched between the inner periphery of the first branch opening 11b, the inner periphery of the second branch opening 12b, and the outer periphery of the branch portion 14. A gate valve or the like may be installed downstream Y2 of the branch portion 14.

[0059] Next, the work valve casing 20 is placed so as to cover the opening 13H of the case part 1, and the work valve 2 is connected to the case part 1 in a sealed state. A seal member is sandwiched between the connecting surfaces of the case part 1 and the work valve 2 to ensure a sealed state. Thereafter, the drilling machine casing 31 is placed so as to cover the opening at the top of the gate valve casing, and the cutter 32 and center drill 40 are housed in the space 31S of the drilling machine casing 31. In this way, the drilling machine 3 is assembled to the case part 1 via the work valve 2.

[0060] Next, we will explain the drilling process for forming the drilling opening Wa by drilling. First, with the center drill 40 and the cutter 32 in the initial position shown in Figure 1, the work valve body 21 is opened to connect the space 31S to the internal space of the case 1. Then, the cutter 32 and the center drill 40 start to rotate, and the drive shaft 34 advances to the lower side Z2.

[0061] The cutting portion 42 of the center drill 40 has flat cutting surfaces 42a, 42a'. When the drive shaft 34 advances and the cutting portion 42 comes into contact with the fluid pipe W, the cutting surfaces 42a, 42a' are the first to come into contact with the fluid pipe W, as shown in FIG. 7 . Compared to cutting surfaces with a sloped cutting edge, the contact area between the fluid pipe W and the cutting surfaces 42a, 42a' is larger in this embodiment. This allows the entire cutting surfaces 42a, 42a' to bear the reaction force from the fluid pipe W, making it less likely for the cutting portion 42 to deviate from the axis WZ. This allows the center drill 40 to perform a drilling operation while maintaining its axis aligned with the axis WX. Furthermore, because the resistance between the fluid pipe W and the cutting surfaces 42a, 42a' is greater, the rotational speed of the center drill 40 is reduced compared to conventional methods, which can also prevent cracks in the fluid pipe W caused by cutting during drilling.

[0062] The cutting portion 42 of the center drill 40 preferably contacts the fluid pipe W after the cutting portion 42 has progressed to a point where a portion of the cutting portion 42 has entered the fluid pipe W, i.e., after the position of the center drill 40 has been fixed relative to the fluid pipe W and the center drill 40 has not escaped outside the fluid pipe W. Even if the cutter 32 comes into contact with the fluid pipe W, the position of the drilling machine 3 relative to the fluid pipe W is fixed by the center drill 40, so the axis WZ of the cutter 32 is unlikely to shift from its initial position. Therefore, even if the fluid pipe W has a small diameter, the axis of the drilling machine 3 will not shift due to the reaction force from the fluid pipe W, and the drilled hole Wa can be formed at the desired position. The cutting portion 42 of the center drill 40 preferably protrudes a predetermined distance downward Z2 from the cutting portion 32a of the cutter 32 so that the positional relationship between the center drill 40 and the cutter 32 is as described above during the drilling process.

[0063] 8, during drilling operation, the movable member 60 is subjected to an inertial force due to the rotation of the shaft portion 41, and enters a second state in which the first side surface 60a approaches the wall surface 45b and the entire movable member 60 is housed in the recess 45. For this reason, even if the shaft portion 41 advances toward the lower side Z2, the fluid pipe W and the movable member 60 will not come into contact with each other.

[0064] As shown in Figure 9, the cutting portion 42 of the center drill 40 and the lower end of the cutter 32 penetrate the fluid pipe W, the cutting portion 42 reaches the vicinity of the notch 121 formed in the bottom surface of the second divided member 12 of the case 1, and the cutter 32 and center drill 40 reach the end position of the drilling operation, completing the drilling operation. With the drilling operation complete, a drilled hole Wa is formed, and a cut portion Wb of the fluid pipe W is produced. When the drive rotation of the cutter 32 and center drill 40 stops, the movable member 60, which was housed in the recess 45 of the shaft 41, is switched to the first state. In this state, the drive shaft 34 retreats to the upper side Z1, performing a return operation, thereby recovering the cut portion Wb.

[0065] When the drive shaft 34 is retracted to the upper side Z1 with the drive rotation of the cutter 32 and the center drill 40 stopped, the movable member 60 protruding from the recess 45 of the shank 41 comes into contact with the cutting portion Wb at a predetermined position in the Z direction, as shown in Figures 10 and 11. At this time, the cutting portion Wb is supported by the shank 41, which penetrates the cutting portion Wb, and the inclined surface 60c of the movable member 60, thereby stabilizing its posture, as shown in Figures 10 and 11. Therefore, with the cutting portion Wb supported by the shank 41, the drive shaft 34 is retracted to the upper side Z1 by a return operation to accommodate the cutter 32 and the center drill 40 in the space 31S, making it possible to remove the cutting portion Wb from the case 1.

[0066] By forming the drilling opening Wa, the inside of the case part 1 and the work valve housing 20, and the space 31S of the drilling machine housing 31 become filled with fluid. After the return operation is completed, the work valve main body 21 is moved to the closed position to close the opening 13H, and the fluid is discharged from the drilling machine housing 31 and the work valve housing 20. Thereafter, the cutter 32 and the center drill 40 are removed to recover the cut portion Wb, and the drilling machine housing 31 is removed from the work valve 2, thereby completing the drilling operation.

[0067] Other Embodiments In the above embodiment, the cutting surfaces 42a, 42a' are formed on a pair of edges that are point-symmetric with respect to the cutter axis WZ, but they do not have to be formed point-symmetrically, and may be formed along the opposing long sides 420, 421 or along the short sides 422, 423. Furthermore, the inclined surfaces 42b, 42b' do not have to be formed, and instead of the inclined surfaces 42b, 42b', there may be a surface that protrudes below the cutting surfaces 42a, 42a' on the lower side Z2 or a surface that retracts above the cutting surfaces 42a, 42a' on the upper side Z1.

[0068] Furthermore, the configurations disclosed in the above embodiments can be applied in combination with configurations disclosed in other embodiments as long as no contradictions arise, and the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0069] The present invention can be used in a branch pipe forming device having a branch portion that can communicate with a drilling port and a method for drilling an existing pipe. [Explanation of symbols]

[0070] 1: Case part 3: Drilling machine 14: Branch 20: Housing for working valve 20a: Support part 32: Cutter 40: Center drill 41: Shaft 42: Cutting part 42a: Cutting surface 42a': Cutting surface 42b: Inclined surface 42b': Inclined surface 45: Recess 45a: Bottom 60: Movable parts 60a: First side 60b:Second side 61: one end 62: Other end 100: Branching pipe forming device W: Fluid pipe (existing pipe) WX: Tube axis WZ: Cutter shaft center Wa: Perforation port Wb: Cutting part

Claims

1. A branch pipe forming device comprising: a case portion attached to the outer surface of an existing pipe in an uninterrupted state; and a drilling machine for forming a drilling hole in a part of the existing pipe, wherein the case portion has a branch portion that can communicate with the drilling hole, The drilling machine includes a cylindrical cutter supported in the case portion so as to be freely reciprocable while rotating around a cutter axis, and a center drill having a shaft portion that protrudes downward from the rotation center position of the cutter and rotates around the cutter axis, When viewed in a direction along the cutter axis, the cutter axis is disposed at a position that is offset from the pipe axis of the existing pipe and overlaps with the existing pipe, The center drill has a cutting portion formed at the tip of the shaft portion, the cutting edge of which includes a flat cutting surface.

2. When viewed in a direction along the cutter axis, the cutting portion has a rectangular shape, 2. The branch pipe forming device according to claim 1, wherein the cutting surfaces are formed on a pair of edges that are point-symmetrical with respect to the cutter axis.

3. the cutting portion has an inclined surface inclined upward from the cutting surface toward an edge opposite to the edge on the side where the cutting surface is formed, The branch pipe forming device according to claim 1 , wherein the cutting surface and the inclined surface are arranged point-symmetrically with respect to the cutter axis.

4. the shaft portion has a recess formed on a side surface of the shaft portion and having a bottom surface inclined downward along a rotation direction of the shaft portion, and a movable member having one end fixed to the bottom surface and another end opposite to the one end movable along the bottom surface, The branch pipe forming device according to claim 1, wherein the movable member is switchable between a first state in which the other end protrudes radially outward from the shaft portion, and a second state in which the entire movable member is accommodated in the recess as the shaft portion rotates.

5. The branch pipe forming device described in claim 4, wherein the movable member has a triangular cross section whose width narrows from the one end to the other end, and a first side surface on the upstream side of the rotation direction is a flat surface with sharp corners, and a second side surface on the downstream side of the rotation direction is a flat surface with chamfered corners.

6. A method for drilling holes in an existing pipe using the branch pipe forming device according to any one of claims 1 to 5, an attachment step of attaching the case portion to an outer surface of the existing pipe in a tight contact state; a drilling step of forming the drilling hole in the existing pipe using the cutter and the center drill.

7. A method for drilling holes in an existing pipe using the branch pipe forming device according to claim 4 or 5, an attachment step of attaching the case portion to an outer surface of the existing pipe in a tight contact state; a drilling step of forming the drilling hole in the existing pipe using the cutter and the center drill; and a recovery step of recovering the cut portion of the existing pipe by lifting up the cutter and the center drill after the drilling step, In the drilling step, the movable member is in the second state when it comes into contact with the existing pipe, A method for drilling an existing pipe, in which the other end of the movable member in the first state and the cut portion are in contact with each other in the recovery step.

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