Cutting device

Abstract

To provide a cutting device capable of easily cutting a pipe buried underground from the inside.SOLUTION: A cutting device cuts a pipe (12) buried underground from the inside, and includes a case (21) attached to a rotatably driven rod (15) and placed inside the pipe (12), a pressing member (22) that can move within the case (21) in the axial direction of the rod (15) by hydraulic pressure supplied into the case (21), and a cutting tool (23) that is supported in a hole (30a) that penetrates an outer periphery (30) of the case (21) and can move radially of the case (21) along the hole (30a). An outer periphery (37a) of the pressing member (22) is provided with a cam surface (38b) that is inclined with respect to the axial direction, and the cam surface (38b) pushes the cutting tool (23) radially outward from the case (21) as the pressing member (22) moves.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cutting device. [Background technology]

[0002] Conventionally, when excavating a tunnel, it is known to provide an observation hole that penetrates from the ground to the tunnel being excavated (see, for example, Patent Document 1). In Patent Document 1, a steel pipe is inserted into a through-hole that penetrates from the ground to the tunnel using a boring machine, and this steel pipe is used as the observation hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-137304 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when a pipe is buried underground as in Patent Document 1, there are cases where it is desired to cut the pipe from the inside. For example, when pulling the pipe out above ground, it is necessary to cut the pipe. However, it is difficult to reach pipes buried underground with a cutting tool, and such pipes are often made of high-strength materials, making cutting the pipe difficult. Cutting the pipe is particularly difficult when the pipe is buried deep below ground level.

[0005] In view of the above, an object of the present invention is to provide a cutting device that can easily cut a pipe buried underground from the inside. [Means for solving the problem]

[0006] The cutting device is a cutting device that cuts a pipe buried underground from the inside, and comprises a case attached to a rotatably driven rod and placed inside the pipe, a pressing member that can move within the case in the axial direction of the rod by hydraulic or gas pressure supplied into the case, and a cutting tool that is supported in a hole that penetrates the outer periphery of the case and can move radially of the case along the hole, and the outer surface of the pressing member is provided with a cam surface that is inclined with respect to the axial direction, and the cam surface pushes the cutting tool radially outward of the case as the pressing member moves. [Effects of the Invention]

[0007] According to the present invention, a cutting device can be provided that can easily cut a pipe buried underground from the inside. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a state in which a pipe is being cut by a boring machine equipped with a cutting device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view showing a cutting device positioned inside a tube. [Figure 3] 3 is a cross-sectional view showing a state in which the cutting of the pipe by the cutting device has progressed further than in FIG. 2. [Figure 4] FIG. 2 is a plan view of the lower wall portion viewed from above. [Figure 5] FIG. [Figure 6] 10 is a bottom view of the lower surface of the pressing member to which the cutting tool is attached, viewed from below. FIG. [Figure 7] FIG. [Figure 8] FIG. 2 is a view of the cutting tool as seen from the axial side of the boring rod. [Figure 9] FIG. 10 is a bottom view of the retainer seen from below. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a cutting device according to the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 is a diagram showing a state in which a pipe 12 is being cut by a boring machine 11 to which a cutting device 10 according to an embodiment of the present invention is attached. The boring machine 11 includes a base 13 placed on the ground G, a frame 14 erected from the base 13, and a drill unit 16 to which a boring rod 15 (rod) for boring holes in the ground is attached.

[0011] The frame 14 supports the drill unit 16 so that the drill unit 16 can slide up and down. The drill unit 16 slides up and down by the power of a movement motor (not shown) provided in the boring machine 11.

[0012] The drill unit 16 includes a main body 16a supported by the frame 14 so as to be slidable up and down, a rotation shaft 16b extending downward from the underside of the main body 16a, and a rod holder 16c provided at the lower end of the rotation shaft 16b. The rotation shaft 16b rotates about a rotation axis 16d extending in the vertical direction. The main body 16a includes a motor (not shown) that rotates the rotation shaft 16b.

[0013] The boring rod 15 has its upper end attached to the rod holding part 16c and extends downward from the rod holding part 16c. The boring rod 15 is attached so that the axis 15a of the boring rod 15 coincides with the rotation axis 16d, and rotates around the rotation axis 16d. A bit (not shown) serving as a cutting part for drilling holes is attached to the lower end of the boring rod 15.

[0014] In Fig. 1, a tunnel T is constructed underground. A boring machine 11 is installed on the ground G above the tunnel T. The boring machine 11 bores a hole in the ground G by moving a rotating boring rod 15 downward using a drill unit 16. The boring machine 11 increases the borehole depth by sequentially adding a plurality of boring rods 15 in the axial direction.

[0015] FIG. 1 shows a through hole H drilled by a boring machine 11. The through hole H is a vertical hole that penetrates from the ground surface to a tunnel T. The through hole H is intended for observation, for example. A pipe 12 is embedded in the through hole H to stabilize the wall of the through hole H. The pipe 12 is a pipe with a circular cross section that extends from the ground surface to the tunnel T. The pipe 12 is made of, for example, carbon steel for mechanical structures.

[0016] In FIG. 1, a cutting device 10 is attached to the lower end of a boring rod 15 in place of the bit. When the through-hole H in which the pipe 12 is buried is used for observation and then the pipe 12 is pulled out to the surface, the pipe 12 is cut midway and divided in the axial direction by the cutting device 10. As an example, Figure 1 shows the state in which the pipe 12 is cut by the cutting device 10 at a position 70 meters underground. The cutting device 10 is disposed inside the pipe 12 and cuts the pipe 12 from the inside by rotating the boring rod 15 .

[0017] Fig. 2 is a cross-sectional view showing the cutting device 10 disposed inside the pipe 12. Fig. 3 is a cross-sectional view showing a state where the cutting of the pipe 12 by the cutting device 10 has progressed further than in Fig. 2. The cutting device 10 comprises a case 21 attached to the boring rod 15 and placed inside the pipe 12, a pressing member 22 movable in the axial direction of the boring rod 15 inside the case 21 by hydraulic pressure supplied into the case 21, and a cutting tool 23 movable in the radial direction of the case 21. The axial direction of the boring rod 15 is the extension direction of the axis 15a, that is, the up-down direction.

[0018] The cutting device 10 also includes a retainer 24 attached to the underside of the pressing member 22, an elastic member 25 that urges the pressing member 22 in the axial direction of the boring rod 15, and a positioning member 26 arranged below the case 21.

[0019] The case 21 comprises a cylindrical outer peripheral portion 30 extending in the axial direction of the boring rod 15, an upper wall portion 31 closing the upper surface of the outer peripheral portion 30, and a lower wall portion 32 closing the lower surface of the outer peripheral portion 30. The outer peripheral portion 30 is a cylinder with a smaller diameter than the inner peripheral surface 12a of the pipe 12, and extends vertically within the pipe 12. The outer peripheral portion 30 is arranged coaxially with the boring rod 15, and the axis of the outer peripheral portion 30 coincides with the axis 15a. Holes 30a are provided in the upper and lower intermediate portions of the outer peripheral portion 30, penetrating the outer peripheral portion 30 in the radial direction of the outer peripheral portion 30. The holes 30a are circular. A plurality of holes 30a are provided at equal intervals around the circumference of the outer peripheral portion 30. In this embodiment, the holes 30a are provided at three locations at intervals of 120° around the circumference.

[0020] The upper wall portion 31 includes an upper fitting portion 31a that fits into the upper end of the inner peripheral surface 30b of the outer peripheral portion 30. The lower portion of the upper fitting portion 31a fits into the inner peripheral surface 30b. The upper wall portion 31 also includes an upper flange portion 31b that protrudes radially outward from the top of the upper fitting portion 31a, and a boring rod connection portion 31c that extends upward from the top surface of the upper fitting portion 31a. Furthermore, the upper wall portion 31 is provided with a ring-shaped seal member 31d in an annular groove formed on the outer periphery of the upper fitting portion 31a. The seal member 31d is, for example, a rubber O-ring.

[0021] The upper flange portion 31b has a plurality of fixing holes 31e that penetrate the upper flange portion 31b from above. Fasteners 33 that fix the upper wall portion 31 to the outer periphery portion 30 are inserted into the fixing holes 31e from above. The upper wall portion 31 is positioned so that the upper fitting portion 31a fits into the inner surface 30b and the upper flange portion 31b abuts against the upper surface of the outer periphery portion 30, and is fastened to the upper surface of the outer periphery portion 30 by a fastener 33 inserted into the fixing hole 31e. The gap between the upper fitting portion 31a and the inner peripheral surface 30b is sealed by a seal member 31d.

[0022] The boring rod connecting portion 31c is cylindrical and extends upward from the center of the upper fitting portion 31a. The upper wall 31 has a communication hole 31f that passes through the upper fitting portion 31a in the vertical direction at the center of the upper fitting portion 31a. The communication hole 31f connects the inside of the boring rod connecting portion 31c and the inside of the case 21.

[0023] FIG. 4 is a plan view of the lower wall portion 32 as viewed from above. 2 to 4, the lower wall portion 32 has a lower fitting portion 32a that fits into the lower end of the inner peripheral surface 30b of the outer peripheral portion 30. The upper portion of the lower fitting portion 32a of the lower wall portion 32 fits into the inner peripheral surface 30b. The lower wall portion 32 also includes a lower flange portion 32b that protrudes radially outward from the lower portion of the lower fitting portion 32a, and a positioning member connecting portion 32c that extends downward from the lower surface of the lower fitting portion 32a. Furthermore, the lower wall portion 32 is provided with a ring-shaped seal member 32d in an annular groove formed on the outer periphery of the lower fitting portion 32a. The seal member 32d is, for example, a rubber O-ring.

[0024] The lower wall portion 32 also has a plurality of fixing holes 32e that pass through the lower flange portion 32b in the vertical direction, and an elastic member holding hole 32f that is provided in the center of the upper surface of the lower fitting portion 32a. A fastener 34 for fixing the lower wall portion 32 to the outer peripheral portion 30 is inserted from below into the fixing hole 32e. The lower wall portion 32 is positioned so that the lower fitting portion 32a fits into the inner surface 30b and the lower flange portion 32b abuts against the underside of the outer periphery 30, and is fastened to the underside of the outer periphery 30 by a fastener 34 inserted through the fixing hole 32e. The gap between the lower fitting portion 32a and the inner peripheral surface 30b is sealed by a seal member 32d. The positioning member connecting portion 32c has a cylindrical shape and extends downward from the lower surface of the center portion of the lower fitting portion 32a.

[0025] Fig. 5 is a cross-sectional view of the pressing member 22. Fig. 6 is a bottom view of the lower surface of the pressing member 22 to which the cutting tool 23 is attached, viewed from below. 2, 3, 5, and 6, the pressing member 22 includes a piston portion 36 that fits into the inner peripheral surface 30b of the outer peripheral portion 30, and a pressing portion 37 that extends downward from the piston portion 36 so as to taper downward. The pressing member 22 is disposed coaxially with the axis 15a.

[0026] The piston portion 36 is cylindrical and fits into the inner peripheral surface 30b. The piston portion 36 is provided with a ring-shaped seal member 36a in an annular groove formed on the outer periphery of the piston portion 36. The gap between the outer periphery of the piston portion 36 and the inner periphery 30b is sealed by the seal member 36a. The pressing member 22 moves up and down as the piston portion 36 slides up and down relative to the inner circumferential surface 30b.

[0027] The pressing portion 37 has a truncated cone shape tapering downward. An outer circumferential surface 37a of the pressing portion 37 has a tapered shape in which the outer diameter decreases downward. The lower surface 37b of the pressing portion 37 is a plane perpendicular to the axis 15a and parallel to the lower surface of the upper wall portion 31.

[0028] The pressing portion 37 includes a guide rail portion 38 that extends from the lower surface 37b to the upper end of the pressing portion 37. The guide rail portion 38 is a T-shaped groove formed from the outer peripheral surface 37a toward the inside of the pressing portion 37. The T-shaped groove is a groove in which the groove width at the bottom side of the groove is larger than the groove width at the shallower part of the groove, giving it a T-shaped cross section. This T-shaped groove extends linearly from the lower surface 37b to the upper end of the pressing portion 37. The guide rail portion 38 is formed parallel to the outer peripheral surface 37a, and is inclined with respect to the axis 15a when viewed from the side perpendicular to the axis 15a as shown in FIG. Further, a center line 38a in the width direction of the guide rail portion 38 intersects with the axis 15a when viewed from below as shown in FIG.

[0029] In detail, the guide rail portion 38 includes a cam surface 38b that forms the bottom surface of the T-shaped groove, a wide groove portion 38c formed on the cam surface 38b side, and a pair of claw portions 38d that define a narrow groove portion on the outer peripheral surface 37a side that is narrower than the wide groove portion 38c. Cam surface 38b is parallel to outer peripheral surface 37a and inclined with respect to axis 15a. That is, cam surface 38b is an inclined surface that inclines so as to approach axis 15a as it goes from the top to the bottom.

[0030] Referring to FIG. 6, the width of the wide groove portion 38c is the same as the width of the cam surface 38b. The claw portion 38d is a protrusion that protrudes inward in the width direction relative to the wide groove portion 38c on the outer peripheral surface 37a side of the wide groove portion 38c. A plurality of guide rail portions 38 are provided at equal intervals in the circumferential direction of the pressing member 22. In this embodiment, the guide rail portions 38 are provided at three locations at intervals of 120° in the circumferential direction. Furthermore, a retainer connection hole 37c to which the retainer 24 is connected is provided in the center of the lower surface 37b of the pressing portion 37.

[0031] Fig. 7 is an enlarged view of the cutting tool 23 in Fig. 2. Fig. 8 is a view of the cutting tool 23 as seen from the axis 15a side. 2 to 3 and 5 to 8, the cutting tool 23 is supported in a hole 30a of the outer peripheral portion 30 and is movable in the radial direction of the case 21 along the hole 30a. The cutting tool 23 has a cylindrical base 41 that fits into the hole 30a. The cutting tool 23 is supported in the hole 30a so that the axis 41a of the base 41 extends in the radial direction of the case 21, and is movable in the radial direction of the case 21 along the axis 41a.

[0032] The cutting tool 23 has a cutting edge 42 at the tip thereof, which extends from the base 41 to the outside in the radial direction of the case 21. The cutting edge 42 is plate-shaped and has a thickness smaller than that of the base 41 in both the top and bottom directions. A connecting portion 43 is provided at the base end of the cutting tool 23, extending from the base portion 41 toward the inside in the radial direction of the case 21. The connecting portion 43 is cylindrical and coaxial with the base portion 41 and has a smaller diameter than the base portion 41.

[0033] The connecting portion 43 is formed with a slider portion 44 that is fitted into the guide rail portion 38 of the pressing portion 37 . The slider portion 44 includes a tool-side cam surface 44a that abuts against the cam surface 38b of the guide rail portion 38, a tool-side claw portion 44b that fits into the wide groove portion 38c of the guide rail portion 38, and a tool-side groove portion 44c into which the claw portion 38d of the guide rail portion 38 fits.

[0034] The tool-side cam surface 44a is an inclined surface formed on the end surface of the cutting tool 23 on the base end side in the axial direction. The tool-side cam surface 44a is parallel to the cam surface 38b and is inclined with respect to the axis 15a. The tool side claw portion 44b and the tool side groove portion 44c extend vertically in parallel with the cam surface 38b. The tool side grooves 44c are grooves formed by cutting out a pair of side surfaces of the connecting portion 43 in the vertical direction.

[0035] Within the guide rail portion 38, the slider portion 44 and the guide rail portion 38 are capable of moving relative to each other along the cam surface 38b. As the pressing member 22 moves up and down, the tool-side cam surface 44a is pressed by the cam surface 38b, and the cutting tool 23 is pushed outward in the radial direction of the case 21. The guide rail portion 38 is fitted into the slider portion 44, thereby restricting the cutting tool 23 from coming off the cam surface 38b and restricting the rotation of the cutting tool 23 about the axis 41a. 6, the cutting tools 23 are disposed on the respective guide rail portions 38. That is, in this embodiment, the cutting tools 23 are provided at three locations at intervals of 120° in the circumferential direction.

[0036] FIG. 9 is a bottom view of the retainer 24 as seen from below. 2, 3 and 9, the retainer 24 includes a disk-shaped receiving plate portion 24a that abuts against the lower surface 37b of the pressing portion 37, an engaging portion 24b that extends upward from the center of the upper surface of the receiving plate portion 24a, and a plurality of holding portions 24c that extend downward from the center of the lower surface of the receiving plate portion 24a.

[0037] The engagement portion 24b of the retainer 24 engages with the retainer connecting hole 37c of the pressing portion 37, thereby restricting radial movement of the retainer 24. The holding portion 24c holds the upper end portion of the elastic member 25. The elastic member 25 is a coil spring. In this embodiment, the elastic members 25 are provided at three locations in the center of the retainer 24 at intervals of 120° in the circumferential direction of the retainer 24.

[0038] The holding portion 24c is a rod-shaped portion that extends downward from the receiving plate portion 24a. The holding portion 24c engages with the inner circumferential surface of the elastic member 25, which is a coil spring, and holds the upper end of the elastic member 25. Three holding portions 24c are provided on the lower surface of the receiving plate portion 24a in correspondence with the elastic members 25.

[0039] The lower end of the elastic member 25 is held in an elastic member holding hole 32f (FIGS. 2 and 4) provided in the upper surface of the lower wall portion 32. The elastic member holding holes 32f are holes that engage with the outer periphery of the lower end of the elastic member 25, which is a coil spring. The elastic member holding holes 32f are arranged at positions that overlap with the holding portions 24c when viewed in the axial direction of the axis 15a.

[0040] The elastic member 25 is disposed between the retainer 24 and the lower wall portion 32, and is disposed in a compressed state between the retainer 24 and the lower wall portion 32. The elastic member 25 biases the pressing member 22 upward via the retainer 24 by a reaction force of the compression.

[0041] Referring to FIG. 2, the positioning member 26 is connected to the positioning member connecting portion 32 c of the lower wall portion 32 and is located below the outer peripheral portion 30 . The positioning member 26 is a disk-shaped member that is disposed coaxially with the axis 15a. The positioning member 26 is connected to the outer periphery of the positioning member connecting portion 32c via a bearing 26a provided in the center of the positioning member 26. The positioning member 26 is rotatable about the positioning member connecting portion 32c.

[0042] As shown in FIG. 2, the outer diameter D of the positioning member 26 is smaller than the inner diameter of the inner circumferential surface 12a of the pipe 12 and is larger than the outer diameter of the outer circumferential portion 30 of the case 21. When the case 21 deviates from the center of the pipe 12, the positioning member 26 abuts against the inner peripheral surface 12a of the pipe 12, and the rebound force of this abutment returns the case 21 to the center of the pipe 12. Because the positioning member 26 is rotatable, part of the force exerted when the positioning member 26 comes into contact with the inner peripheral surface 12a can be released by the rotation of the positioning member 26. As a result, excessive repulsion can be prevented, and the case 21 can be well positioned.

[0043] 2, the upper flange portion 31b of the upper wall portion 31 has a diameter larger than the outer diameter of the outer peripheral portion 30 of the case 21, and the outer shape of the upper flange portion 31b is substantially the same as the outer diameter D of the positioning member 26. Therefore, the case 21 can also be positioned in the radial direction by the upper flange portion 31b above the case 21.

[0044] 2 and 3, the cutting device 10 is connected to the boring rod 15 by screwing the outer periphery of the lower end of the boring rod 15 into the inner periphery of the boring rod connecting portion 31c of the upper wall portion 31. The boring rod 15 is connected to a pump (not shown) that serves as a liquid pressure supply unit. The liquid pressure-fed by the pump passes through the hollow boring rod 15 and is supplied to the cutting device 10 side. The liquid in the boring rod 15 passes through the communication hole 31f of the upper wall portion 31 and is supplied into the case 21. In this embodiment, the liquid supplied into the case 21 by the pump is water. A pressure reducing unit 39 (see FIG. 1) for reducing the hydraulic pressure is provided in the hydraulic pressure supply path for the boring rod 15. The pressure reducing unit 39 is, for example, a switching valve that can discharge the liquid in the hydraulic pressure supply path to the outside by switching the valve.

[0045] Here, an example of the procedure for cutting the pipe 12 using the cutting device 10 will be described. Referring to Figure 2, the cutting device 10 is set at a depth corresponding to a predetermined cutting position of the pipe 12, and as the drilling unit 16 drives and rotates the boring rod 15, the cutting device 10 rotates integrally with the boring rod 15.

[0046] FIG. 2 shows the initial position where no hydraulic pressure is supplied by the pump. In the initial position, the upper surface of the piston portion 36 of the pressing member 22 is brought into contact with the lower surface of the upper wall portion 31 by the biasing force of the elastic member 25 . In addition, in the initial position, the slider portion 44 of the cutting tool 23 is located at the lower end of the guide rail portion 38, and the blade portion 42 of the cutting tool 23 is spaced radially inward from the inner surface 12a of the pipe 12.

[0047] 3, when hydraulic pressure is supplied by the pump from the initial position state of FIG. 2, the hydraulic pressure presses the pressing member 22, and the pressing member 22 moves downward against the biasing force of the elastic member 25. 3 shows the pressing member 22 in the lowest position where it has moved to the lowest position. In this state, the slider portion 44 of the cutting tool 23 is located at the upper end of the guide rail portion 38. When the pressing member 22 begins to descend due to the liquid pressure, a pressurizing chamber 45 in which liquid accumulates is formed between the lower surface of the upper wall portion 31 and the upper surface of the piston portion 36 within the outer circumferential portion 30. As the pressing member 22 descends, the pressurizing chamber 45 becomes larger in the vertical direction, and the amount of compression of the pressing member 22 increases accordingly.

[0048] When the pressing member 22 is lowered by the hydraulic pressure, the guide rail portion 38 of the pressing member 22 moves downward relative to the slider portion 44 while being fitted in the slider portion 44 of the cutting tool 23. As a result, the slider portion 44 slides relatively within the guide rail portion 38 along the cam surface 38b. More specifically, when the pressing member 22 is lowered by hydraulic pressure, the tool-side cam surface 44a of the slider portion 44 is pressed radially outward by the cam surface 38b of the guide rail portion 38, and the cutting tool 23 moves radially outward within the hole 30a of the outer circumferential portion 30. As a result, the blade portion 42 of the cutting tool 23 is pressed against the inner circumferential surface 12a of the pipe 12. The first moving direction S1 (FIG. 3), which is the moving direction of the pressing member 22 when pushing the cutting tools 23 outward in the radial direction, is downward. The cutting tools 23 provided at three locations are pushed out approximately evenly.

[0049] With the cutting device 10 rotating integrally with the boring rod 15, the pressing member 22 is moved in the first movement direction S1 by hydraulic pressure, and the blade portion 42 of the cutting tool 23 is pressed against the inner peripheral surface 12a of the pipe 12, cutting the inner peripheral surface 12a with the blade portion 42. Figure 3 shows the state in which the blade portion 42 has penetrated the pipe 12 and completely cut the pipe 12. While the cutting tool 23 is cutting the inner circumferential surface 12a, the hydraulic pressure supplied to the pressurizing chamber 45 is adjusted so that the pressing force of the blade portion 42 against the inner circumferential surface 12a is an appropriate magnitude. The hydraulic pressure can be adjusted by controlling the supply pressure of the pump and operating the pressure reducing portion 39. In this embodiment, the liquid that generates the hydraulic pressure is water, so that the heat generated by the pressing member 22 and the cutting tool 23 during cutting can be effectively absorbed by the water.

[0050] 3, when the hydraulic pressure in the pressurizing chamber 45 decreases and the biasing force of the elastic member 25 exceeds the hydraulic pressure pressing the pressing member 22, the pressing member 22 moves in a second movement direction S2 (FIG. 2), which is the opposite direction to the first movement direction S1, due to the biasing force of the elastic member 25. The second movement direction S2 is an upward direction.

[0051] When the pressing member 22 moves in the second movement direction S2, the slider portion 44 is pulled radially inward of the outer periphery 30 by the guide rail portion 38, and the cutting tool 23 moves radially inward of the outer periphery 30. For example, when it is desired to retract the cutting tool 23 while cutting the pipe 12, or when cutting of the pipe 12 is completed, the hydraulic pressure can be reduced by the pressure reducing section 39, and the force of the elastic member 25 can be used to automatically retract the cutting tool 23 relative to the inner surface 12a. The biasing force of the elastic member 25 is given a predetermined initial load so that the pressing member 22 is not pushed down by the head of liquid accumulated in the boring rod 15 when the pump is not operating.

[0052] As described above, according to the embodiment to which the present invention is applied, the cutting device 10 is a cutting device that cuts a pipe 12 buried underground from the inside, and includes a case 21 attached to a rotationally driven boring rod 15 and placed inside the pipe 12, a pressing member 22 that can move within the case 21 in the axial direction of the boring rod 15 by hydraulic pressure supplied into the case 21, and a cutting tool 23 that is supported in a hole 30a that penetrates an outer periphery 30 of the case 21 and can move radially of the case 21 along the hole 30a. A cam surface 38b inclined with respect to the axial direction of the boring rod 15 is provided on an outer periphery 37a of the pressing member 22, and the cam surface 38b pushes the cutting tool 23 radially outward from the case 21 as the pressing member 22 moves. According to this configuration, when hydraulic pressure is supplied to the case 21 attached to the rotationally driven boring rod 15 and placed inside the pipe 12, the hydraulic pressure moves the pressing member 22 in the axial direction of the boring rod 15, and the cutting tool 23 is pushed outward in the radial direction of the case 21 by the cam surface 38b of the pressing member 22. This allows the cutting tool 23 to be pressed against the pipe 12 from the inside, making it possible to easily cut the pipe 12 buried underground from the inside.

[0053] Furthermore, the pressing member 22 includes a guide rail portion 38 that restricts the separation of the cutting tool 23 from the cam surface 38b and moves the cutting tool 23 along the cam surface 38b. When the pressing member 22 moves in a direction (second movement direction S2) opposite to the first movement direction S1, which is the movement direction of the pressing member 22 when pushing the cutting tool 23 radially outward, the cutting tool 23 moves radially inward of the case 21 via the guide rail portion 38. According to this configuration, by moving the pressing member 22 in the opposite direction, the cutting tool 23 can be moved radially inward of the case 21 via the guide rail portion 38, and the cutting tool 23 can be retracted from the inner surface 12a of the pipe 12.

[0054] In addition, an elastic member 25 is provided to bias the pressing member 22 in the second movement direction S2. According to this configuration, the pressing member 22 can be moved in the second movement direction S2 by the biasing force of the elastic member 25, and the cutting tool 23 can be moved inward in the radial direction of the case 21.

[0055] Furthermore, the case 21 includes a cylindrical outer peripheral portion 30, an upper wall portion 31 that closes the upper surface of the outer peripheral portion 30, and a lower wall portion 32 that closes the lower surface of the outer peripheral portion 30. The boring rod 15 is connected to the upper wall portion 31, and a pressurizing chamber 45 to which hydraulic pressure is supplied is provided between the upper wall portion 31 and the pressing member 22. The hydraulic pressure is supplied to the pressurizing chamber 45 through the boring rod 15, and an elastic member 25 is disposed between the pressing member 22 and the lower wall portion 32. According to this configuration, hydraulic pressure is supplied to the pressurizing chamber 45 through the boring rod 15, and this hydraulic pressure moves the pressing member 22 against the biasing force of the elastic member 25, thereby pushing the cutting tool 23 radially outward from the case 21. Therefore, the pipe 12 can be easily cut from the inside with a simple structure.

[0056] Further, a disk-shaped positioning member 26 is provided, which is arranged coaxially with the case 21, and the outer diameter D of the positioning member 26 is smaller than the inner diameter of the pipe 12 and larger than the outer diameter of the outer peripheral portion 30 of the case 21. According to this configuration, the positioning member 26 can position the case 21 at the center of the pipe 12, so that the cutting tool 23 can be pressed appropriately against the pipe 12, and the pipe 12 can be cut efficiently.

[0057] A plurality of cutting tools 23 are provided at equal intervals in the circumferential direction of outer periphery 30 of case 21 . According to this configuration, multiple cutting tools 23 are provided at equal intervals in the circumferential direction of the outer periphery 30 of the case 21, so that when the cutting tools 23 come into contact with the pipe 12 from the inside, the case 21 is positioned at the center of the pipe 12 by the multiple cutting tools 23. Therefore, each cutting tool 23 can be appropriately pressed against the pipe 12, and the pipe 12 can be cut efficiently.

[0058] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and unless otherwise limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as defined in the claims. For example, the configurations of the above-described embodiment may be added or deleted as appropriate, and the configurations of one embodiment may be incorporated into other embodiments. Furthermore, the effects of the above-described embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above-described effects. In the above embodiment, the pressing member 22 is described as being movable in the axial direction of the boring rod 15 within the case 21 by hydraulic pressure, but the present invention is not limited to this. The pressing member 22 may be movable in the axial direction of the boring rod 15 within the case 21 by the pressure of gas such as air supplied into the case 21. [Explanation of symbols]

[0059] 10: Cutting device 12:Tube 15: Boring Rod (Rod) 21: Case 22: Pressing member 23: Cutting tool 25: Elastic member 26: Positioning member 30: Outer periphery 30a: hole 31: Upper wall part 32: Lower wall part 37a: Outer surface 38: Guide rail section 38b: Cam surface 45: Pressure chamber D:Outer diameter

Claims

1. A cutting device for cutting underground pipes from the inside, a case attached to a rod that is driven to rotate and disposed within the pipe; a pressing member that is movable within the case in the axial direction of the rod by hydraulic or gas pressure supplied into the case; and a cutting tool that is supported in a hole that penetrates the outer periphery of the case and is movable in the radial direction of the case along the hole, a cam surface inclined with respect to the axial direction is provided on the outer peripheral surface of the pressing member; A cutting device in which the cam surface pushes the cutting tool radially outwardly of the case as the pressing member moves.

2. the pressing member includes a guide rail portion that restricts the cutting tool from leaving the cam surface and moves the cutting tool along the cam surface, 2. The cutting device according to claim 1, wherein when the pressing member moves in a direction opposite to the direction of movement of the pressing member when pushing the cutting tool radially outward, the cutting tool moves radially inward of the case via the guide rail portion.

3. 3. The cutting device according to claim 2, further comprising an elastic member for biasing the pressing member in the opposite direction.

4. the case includes a cylindrical outer peripheral portion, an upper wall portion that closes an upper surface of the outer peripheral portion, and a lower wall portion that closes a lower surface of the outer peripheral portion, The rod is connected to the upper wall portion, a pressure chamber to which the liquid pressure or the gas pressure is supplied is provided between the upper wall portion and the pressing member, The liquid pressure or the gas pressure is supplied to the pressurizing chamber through the rod, The cutting device according to claim 3 , wherein the elastic member is disposed between the pressing member and the lower wall portion.

5. 2. The cutting device according to claim 1, further comprising a disk-shaped positioning member arranged coaxially with the case, the outer diameter of the positioning member being smaller than the inner diameter of the pipe and larger than the outer diameter of the outer periphery of the case.

6. The cutting device according to claim 1 , wherein a plurality of the cutting tools are provided at equal intervals in the circumferential direction of the outer periphery of the case.

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