JP5608888B2 - Cutting tool for expanding existing pipes - Google Patents

Description

  The present invention relates to a cutting tool for expanding the diameter of an existing pipeline that cuts an inner wall so as to expand the diameter of the existing pipeline.

  Many existing pipes with relatively small diameters, such as for electrical wiring, are installed sideways so that both ends open into manholes, etc., and one end opens into the coffin and the other end is closed to prevent humans from entering Some open to space. Some have existing pipelines that are arranged vertically like a chimney flue. When expanding the diameter of an existing pipe line that is relatively small in diameter and cannot be entered by a person for repairs such as renewing the lining or increasing the cross-sectional capacity, around the support shaft inserted into the existing pipe line Using a cutting tool for diameter expansion in which a plurality of cutting blades are arranged radially, moving the support shaft in one direction by pulling or pushing while rotating the support shaft, and using a cutting blade having a cutting diameter larger than the inner diameter of the existing pipe line, A diameter expansion method is employed in which an inner wall of an existing pipeline is cut from one end side to the other end side (see, for example, Patent Document 1).

  This kind of existing pipeline is formed of concrete, a fume pipe, a synthetic resin pipe or the like. Further, the support shaft of the diameter-enlarging cutting tool is connected to a rotary traction device or a rotary push-in device arranged outside the existing pipe line by an extension rod. When expanding the diameter of a long existing pipeline, the support shaft at the time of cutting is often moved from the back side to the near side of the existing pipeline by traction so that the extension rod does not bend or buckle.

  In addition, in the cutting tool for expanding the diameter of the existing pipe line, a plurality of pedestals having cutting tips at the top are installed on the outer peripheral surface of the cylindrical bit body mounted on the support shaft so as to be movable in the radial direction. In addition, there has been proposed a technique in which these pedestals are urged radially outward by a spring material to partially cut a stepped portion or the like of a joint portion of an existing pipeline (for example, Patent Document 2). reference).

JP 2001-262971 A JP 2004-316304 A

The cutting tool for expanding the diameter of the existing pipe described in Patent Document 1 has the following problems because the cutting diameter of the cutting blade is larger than the inner diameter of the existing pipe.
(1) When the support shaft at the time of cutting is moved by towing, a work space and an operator are required for mounting the cutting blade on the support shaft inserted to the far side of the existing pipeline.
(2) If the support shaft at the time of cutting is moved by being pushed in and the existing pipe is in a closed space where no people can enter, the cutting blade cannot be recovered.
(3) In long existing pipelines, the transmission efficiency of rotational torque to the support shaft decreases due to torsional deformation of the long extension rod.
(4) Existing pipes cannot be expanded from the middle.
(5) When trouble occurs, the support shaft cannot be returned to the opposite side.

  Therefore, the problem of the present invention is that it does not require a work space and an operator on the back side of the existing pipeline, the cutting blade can be collected in any case, and the length of the extension rod can be shortened with a long existing pipeline, An object of the present invention is to provide a cutting tool for expanding the diameter of an existing pipe line that can return the support shaft to the opposite side even when a trouble occurs.

In order to solve the above-described problems, the present invention provides a plurality of cutting blades arranged radially around a support shaft inserted into an existing pipe line, while rotating the support shaft provided with the cutting blades. through the existing pipe by moving, in diameter for a cutting tool of the existing pipe line for cutting the inner wall to enlarged the existing pipeline, prevented from rotating the tubular base member to the support shaft axis The base member is provided with a plurality of storage portions that are open to the outer diameter side so that the plurality of cutting blades can be slid in the radial direction and can not be moved relative to each other in the circumferential direction. Means for urging each cutting blade stored in the storage portion inward in the radial direction, and protrudes from the base side of each cutting blade to the inner diameter surface of the pedestal member so as to be in contact with the outer diameter surface of the support shaft. An abutting portion is provided, and the outer diameter of the supporting shaft that the abutting portion abuts is increased in a monotonically increasing direction. Provided part, the support shaft during cutting moving the push direction or pullback direction to the existing pipeline, said base member is slid to the large diameter side of the enlarged diameter portion, the contact portion of the cutting edge Is engaged with the large diameter side of the enlarged diameter portion, the tip of each cutting blade accommodated in the accommodating portion is pushed outward in the radial direction, and when the support shaft is moved in the direction opposite to that during cutting, The base member is slid to the smaller diameter side of the enlarged diameter portion, the contact portion of each cutting blade is engaged with the smaller diameter side of the enlarged diameter portion, and the cutting blade is accommodated in the accommodating portion. Adopted.

That is, a cylindrical pedestal member is prevented from rotating on the support shaft and is externally fitted to be slidable in the axial direction. A plurality of cutting blades can be slid in the radial direction on the pedestal member , and relative movement in the circumferential direction is impossible provided with a plurality of housing portions that opens radially outward to be received in inner diameter surface of the means for biasing each cutting edge radially inwardly to be received in the receiving portion, the base member from the base side of the cutting edge A contact portion that protrudes in contact with the outer diameter surface of the support shaft is provided, and a diameter expansion portion in which the outer diameter monotonously increases in one direction is provided at a portion of the support shaft that contacts the contact portion. When the support shaft is moved in the cutting direction , the pedestal member is slid to the large diameter side of the large diameter portion, and the contact portion of each cutting blade is engaged with the large diameter side of the large diameter portion. When pushing the tip of each cutting blade stored in the storage portion radially outward and moving the support shaft in the direction opposite to that during cutting, The seat member is slid to the smaller diameter side of the enlarged diameter portion, the contact portion of each cutting blade is engaged with the smaller diameter side of the enlarged diameter portion, and each cutting blade is accommodated in the accommodating portion, so that the depth of the existing pipe line is increased. The cutting blade can be collected in any case without the need for a work space and workers on the side, and the length of the extension rod can be shortened by dividing a long existing pipe line so that the diameter of the extension rod can be reduced. Can be returned to the other side.

  In addition, this cutting tool for expanding the diameter of the existing pipe line naturally pushes the cutting blade by moving in the cutting direction, and does not require a separate drive source, so electric wiring, hydraulic pipes, etc. are installed in the existing pipe line. There is no need to guide it, and it can be inserted into an existing pipe line simply by connecting an extension rod, as in a conventional cutting tool for expanding the diameter.

  The expanded diameter portion of the support shaft may be a tapered portion whose outer diameter increases linearly.

The cylindrical portion outer diameter is constant in the large diameter side of the enlarged diameter portion is provided, engages when moving the support shaft in a direction cutting is performed, the contact portion of each cutting edge to the cylindrical portion By combining, the tip diameter of the cutting blade at the time of cutting can be stably set to a predetermined cutting diameter.

  By forming the part of the support shaft with the enlarged-diameter portion with a separate enlarged member and making the separate enlarged member replaceable, the amount of enlarged diameter of the enlarged member is different. By changing the extrusion amount of each cutting blade, it is possible to cut existing pipes having different diameter expansion dimensions.

  The means for urging the cutting blade radially inward may be a tension coil spring that is mounted around the contact portion and that urges the cutting blade radially inward.

  The cutting blade can be made inexpensive by inserting the contact portion into a through-hole provided in the bottom of the storage portion and connecting or contacting the base side of the cutting blade. Can be processed.

  Means for supplying pressure water to the large-diameter side space of the enlarged-diameter portion in the pedestal member is provided, and the pedestal member is adjusted by the pressure water pressure supplied to the large-diameter side space of the enlarged-diameter portion. By sliding to the large-diameter side of the large-diameter portion, the base member is slid to the large-diameter side of the large-diameter portion by the pressure water at the start of cutting, and the cutting blade is gradually pushed outward to rotate. The blade can be smoothly cut into the inner wall of the existing pipeline to be cut.

The pressure water supplied to the space on the large-diameter side of the large-diameter portion is moved to the outer diameter side of the pedestal member on the front side in the moving direction of the cutting blades when the support shaft is moved in the cutting direction. By providing the means for discharging, the pressure water discharged to the front side in the moving direction of the cutting blade can be used as cutting water, and the cutting efficiency can be increased.

The cutting tool for expanding the diameter of an existing pipe line of the present invention has a cylindrical pedestal member that is prevented from rotating on a support shaft and is slidably fitted in the axial direction, and a plurality of cutting blades are radially attached to the pedestal member. A plurality of storage portions opened to the outer diameter side for slidably storing are provided, a means for urging each cutting blade stored in the storage portion inward in the radial direction, and a base member from the base side of each cutting blade An abutting portion that protrudes from the inner diameter surface and abuts against the outer diameter surface of the support shaft is provided, and an enlarged diameter portion whose outer diameter monotonously increases in one direction is provided at a portion of the support shaft that abuts the abutting portion. provided, when moving the supporting lifting axis in a direction cutting takes place, slide the seat member to the large diameter side of the enlarged diameter portion, engaged with the large diameter side of the enlarged diameter portion abutting portions of the cutting edge When the tip of each cutting blade stored in the storage portion is pushed outward in the radial direction, and the support shaft is moved in the direction opposite to that during cutting, the base member Since the sliding part is slid to the small diameter side of the enlarged diameter part and the contact part of each cutting blade is engaged with the small diameter side of the enlarged diameter part, each cutting blade is stored in the storage part. The cutting blade can be collected in any case, and the length of the extension rod can be shortened by dividing the long existing pipe line so that the diameter of the extension rod can be shortened. Can be returned to the other side. In addition, this cutting tool for expanding the diameter of the existing pipe line naturally pushes the cutting blade by moving in the cutting direction, and does not require a separate drive source, so electric wiring, hydraulic pipes, etc. are installed in the existing pipe line. There is no need to guide it, and it can be inserted into an existing pipe line simply by connecting an extension rod.

The longitudinal cross-sectional view which shows the cutting tool for diameter expansion of the existing pipe line of 1st Embodiment Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. The longitudinal cross-sectional view which shows the state when moving the cutting tool for diameter expansion of FIG. 1 in the reverse direction at the time of cutting Sectional drawing which shows Example 1 which expands an existing pipe diameter using the cutting tool for diameter expansion of FIG. Sectional drawing which shows Example 2 which expands an existing pipe line diameter using the cutting tool for diameter expansion of FIG. The longitudinal cross-sectional view which shows the cutting tool for diameter expansion of the existing pipe line of 2nd Embodiment The longitudinal cross-sectional view which shows the state when moving the cutting tool for diameter expansion of FIG. 7 in the reverse direction at the time of cutting Sectional drawing which shows Example 3 which expands an existing pipe diameter using the cutting tool for diameter expansion of FIG. The longitudinal cross-sectional view which shows the cutting tool for diameter expansion of the existing pipe line of 3rd Embodiment 10 is a longitudinal sectional view showing a state when the diameter-enlargement cutting tool in FIG. 10 is moved in the direction opposite to that during cutting.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. This cutting tool for expanding the diameter of an existing pipe pulls the support shaft and cuts the inner wall. As shown in FIGS. 1 to 3, the support shaft 1 inserted into the existing pipe has a cylindrical shape. The pedestal member 2 is prevented from rotating by the engagement of the slide key 3a and the key groove 3b, and is externally fitted so as to be slidable in the axial direction. The pedestal member 2 has six storage portions 4 opened to the outer diameter side. The six cutting blades 5 are radially accommodated so as to be slidable in the radial direction, and a separate pin-shaped contact member 6 screwed to the base side is fitted into the through hole 7 at the bottom of the accommodating portion 4. Each cutting blade 5 is urged radially inward by a tension coil spring 8 that is inserted and protrudes to the inner diameter surface of the pedestal member 2, and is mounted around the contact member 6. It comes to contact | abut to the outer-diameter surface. A cemented carbide chip 5a is built up on the tip of each cutting blade 5, and the traveling direction during cutting is cut out in a tapered shape.

  The support shaft 1 is attached to a rotary traction device (not shown) disposed outside an existing pipe line via an extension rod 24 and is screwed to the tip of the base member 1a. A separate member having a tapered portion 9a that expands in the direction opposite to the traction side and an equal-diameter portion 9b on the large-diameter side as an enlarged-diameter portion with which the abutting member 6 of the cutting blade 5 abuts on the outer diameter surface. It consists of an enlarged member 1b.

  At both ends of the pedestal member 2, inward flanges 10 a and 10 b for sealing a space between the support shaft 1 are provided. 1 is engaged with a large-diameter step portion 11a provided on the base member 1a, and the left-side flange 10b is engaged with a large-diameter step portion 11b provided on the diameter-expanding member 1b. Thus, the slide stroke of the base member 2 is regulated. Sliding keys 3a that engage with the key grooves 3b of the base member 2 are provided on the outer diameter surfaces of the large diameter step portions 11a and 11b of the base member 1a and the diameter expanding member 1b.

  As shown in FIG. 1, when the support shaft 1 is pulled rightward from the back side of the existing pipe line to the near side during cutting, first, the pedestal member 2 is caused by frictional resistance with the inner wall of the pipe line. By sliding to the left, the contact member 6 moves to the larger diameter side of the taper portion 9a, and the tip of each cutting blade 5 is pushed out from the storage portion 4 in the radial direction. When each of the extruded cutting blades 5 is pressed against the inner wall of the pipe line, the pedestal member 2 slides further to the left by the pressing resistance, and the flange 10a is locked to the large-diameter step portion 11a of the base member 1a. The contact member 6 engages with the equal diameter portion 9b. When cutting is started as the support shaft 1 is driven to rotate, the scissors 10a are pressed against the large-diameter step portion 11a by the cutting resistance, and the contact members 6 that engage with the equal-diameter portion 9b are used for the cutting blades 5a. The cutting diameter is kept constant.

  As shown in FIG. 4, when the support shaft 1 is inserted leftward into the existing pipe before cutting, the base member 2 slides to the right of the support shaft 1 due to frictional resistance with the inner wall of the pipe. Then, the flange 10b is locked to the large-diameter step portion 11b of the diameter-expanding member 1b. At this time, the contact member 6 that contacts the tapered portion 9a of the diameter-expanding member 1b engages with the small-diameter side of the tapered portion 9a, and each cutting blade 5 biased radially inward by the tension coil spring 8 is stored. Housed in part 4.

  FIG. 5 shows a first embodiment in which the diameter of the existing pipe line 22 that is disposed in the lateral direction so that both ends are opened to the manholes 21a and 21b is expanded by using the above-described diameter expansion cutting tool. In the first embodiment, the rotary traction device 23 a is arranged in the right manhole 21 a, and the support shaft 1 on which the pedestal member 2 in which each cutting blade 5 is accommodated in the accommodating portion 4 is mounted is rotated via the extension rod 24. Each of the cuttings connected to the traction device 23a, inserted into the existing pipe 22 through the manhole 21a, and pushed out radially outward from the storage portion 4 while being pulled to the right near side by the rotary traction device 23a. The inner wall of the existing pipeline 22 is cut with the blade 5. Therefore, in the first embodiment, an operator in the left manhole 21b can be made unnecessary.

  6 (a) and 6 (b) show a long existing pipe line which is disposed sideways so as to open to the two manholes 21a and 21b using the above-described cutting tool for expanding the diameter as in the first embodiment. Example 2 in which the diameter of 22 is expanded is shown. In the second embodiment, first, as shown in FIG. 6A, a support shaft on which a rotary traction device 23 a is disposed in the right manhole 21 a and a base member 2 in which each cutting blade 5 is stored in the storage portion 4 is mounted. 1 is connected to the rotary traction device 23a via the extension rod 24, inserted from the manhole 21a to the middle portion of the existing pipe line 22, and pushed outward from the storage portion 4 while being pulled rightward. The inner wall of the right half of the existing pipeline 22 is cut by each cutting blade 5. After that, as shown in FIG. 6B, the rotary traction device 23a is arranged in the left manhole 21b, and similarly, the support shaft 1 connected to the rotary traction device 23a via the extension rod 24 is connected to the manhole 21b. To the middle part of the existing pipeline 22 and the remaining inner wall of the left half is cut while being pulled leftward. Therefore, in the second embodiment, the length of the extension rod 24 can be shortened to about half of the length of the existing pipeline 22.

  7 and 8 show a second embodiment. This diameter-enlarging cutting tool for existing pipes is for cutting the inner wall by pushing the support shaft. As shown in FIG. 7, the diameter-enlarged portion of the diameter-expanding member 1b of the support shaft 1 is the base member 1a side. Are formed of a tapered portion 9a that expands toward the push-in side and an equal-diameter portion 9b on the large-diameter side. The other portions are the same as those of the first embodiment, and inward ends of the base member 2 are provided with inward flanges 10a and 10b for sealing the space between the support shaft 1 and FIG. 7 on the right side 7 is locked in two directions on two large-diameter steps 11a and 11b provided on the base member 1a to restrict the sliding stroke of the base member 2.

  In this embodiment, as shown in FIG. 7, when the support shaft 1 is pushed to the left from the near side of the existing pipe line during cutting, the pedestal member 2 is moved to the right side of the support shaft 1 by frictional resistance with the inner wall of the pipe line. The abutting member 6 moves to the larger diameter side of the tapered portion 9a, and the tip of each cutting blade 5 is pushed out from the storage portion 4 in the radial direction. When each cutting blade 5 is pressed against the inner wall of the pipe line, the base member 2 slides further to the right due to the pressing resistance, and the flange 10b is locked to the large-diameter step portion 11b of the diameter-expanding member 1b. The member 6 engages with the equal diameter portion 9b. When cutting is started as the support shaft 1 is driven to rotate, the scissors 10b are pressed against the large-diameter step portion 11b by the cutting resistance, and the contact members 6 engaged with the equal-diameter portions 9b are used to contact each cutting blade 5 with each other. The cutting diameter is kept constant. Further, as shown in FIG. 8, when the support shaft 1 is pulled back to the front side of the existing pipeline after cutting, the base member 2 slides to the left of the support shaft 1 due to frictional resistance with the inner wall of the pipeline. The hook 10a is locked to the large-diameter step portion 11a of the base member 1a, and the contact member 6 engages with the small-diameter side of the taper portion 9a, and is urged radially inward by the tension coil spring 8. The cutting blade 5 is stored in the storage unit 4.

  FIG. 9 shows a third embodiment in which, using the above-described cutting tool for expanding the diameter, the diameter of the existing existing pipeline 22 having one end opened in the manhole 21 and the other end opened in the closed space 25 where no person can enter is expanded. Show. In the third embodiment, the rotary pushing device 23b is arranged in the manhole 21, and the support shaft 1 on which the base member 2 in which each cutting blade 5 is housed in the housing portion 4 is mounted is provided on the left side by the rotational pushing device 23b. The inner wall of the existing pipe line 22 is cut by the cutting blades 5 pushed radially outward from the storage portion 4 while being pushed into the back side of the pipe line 22, and the extension rod 24 is moved as the support shaft 1 advances to the back side. Are sequentially connected. When the diameter expansion is completed to the closed space 25 at the back of the existing pipeline 22, the support shaft 1 is pulled back to the right on the near side, and at this time, each cutting blade 5 is stored in the storage unit 4. Therefore, in Example 3, each cutting blade 5 can be collected from the back side of the existing pipeline 22.

  Further, in the first to third embodiments described above, even if some trouble occurs during cutting, each of the cutting blades 5 can be stored in the storage portion 4 and the support shaft 1 on which the base member 2 is mounted can be pulled back to the opposite side. So you can easily deal with troubles.

  10 and 11 show a third embodiment. The existing pipe diameter increasing cutting tool has the same basic configuration as that of the first embodiment, and, as shown in FIG. 10, the large diameter of the diameter expanding member 1b in the base member 2 is large. The difference is that pressure water is supplied to the side space from a water supply pipe 14 connected to the hose 12 via a swivel 13.

  The water supply pipe 14 is slidably passed through the flange 10b and inserted into the pedestal member 2, and the tip is connected to the large diameter step portion 11b on the large diameter side of the diameter expanding member 1b. Pressure water is supplied from the water supply hole 14a provided at the tip to the space on the large diameter side of the diameter expanding member 1b. The space on the large-diameter side of the diameter-expanding member 1b is water-sealed by a seal ring 15a attached to the outer diameter surface of the large-diameter step portion 11b and a seal ring 15b attached to the inner diameter surface of the flange 10b. Therefore, by supplying pressure water from the water supply pipe 14 at the start of cutting, the base member 2 is moved to the larger diameter side of the enlarged diameter portion 1b by the pressure water pressure, and each cutting blade 5 is gradually pushed outward. It is possible to smoothly cut the rotating cutting blade 5 into the inner wall of the pipe line to be cut.

  The space on the large diameter side of the diameter-expanding member 1b is formed through a through hole 16 provided in the bottom of the storage portion 4 of each cutting blade 5 and a through hole 7 into which the contact member 6 is inserted. While communicating with the space on the small diameter side of the diameter expanding member 1b, the base member 2 opens from the space on the small diameter side of the diameter expanding member 1b to the outer diameter surface on the front side in the movement direction during cutting of each cutting blade 5. A drain hole 17 is provided. The space on the small diameter side of the expanded diameter member 1b is formed by a seal ring 15a attached to the outer diameter surface of the large diameter step portion 11b and a seal ring 15c attached to the outer diameter surface of the large diameter step portion 11a of the base member 1a. It is sealed with water. Therefore, by supplying pressure water from the water supply pipe 14 into the pedestal member 2 at the time of cutting, the expanded pressure member passes through the through hole 16 and the through hole 7 from the large diameter side space of the expanded diameter member 1b. The pressure water that has been fed into the space on the small diameter side of 1b and ejected from the drain hole 17 to the front side in the moving direction of each cutting blade 5 can be used as cutting water.

  As shown in FIG. 11, when the support shaft 1 is inserted leftward into the existing pipe before cutting, the supply of pressure water from the water supply pipe 14 is stopped, and the first embodiment is used. Similarly, the pedestal member 2 slides to the right of the support shaft 1 due to frictional resistance with the pipe inner wall, and the flange 10b is locked to the large-diameter step portion 11b of the diameter-expanding member 1b. The abutting member 6 that abuts on the tapered portion 9 a engages with the small diameter side of the tapered portion 9 a, and each cutting blade 5 biased radially inward by the tension coil spring 8 is accommodated in the accommodating portion 4.

  In the third embodiment described above, as in the first embodiment, the support shaft 1 is pulled to cut the inner wall, but as in the second embodiment shown in FIG. When the inner wall is cut by pushing the support shaft 1, the pressure water is moved from the side where the base member 1 a of the support shaft 1 is inserted into the space on the large diameter side of the diameter-expanding member 1 b in the base member 2. By supplying, the base member 2 can be moved to the larger diameter side of the enlarged diameter portion 1b by the pressure water at the start of cutting, and each cutting blade 5 can be gradually pushed outward.

  In each of the above-described embodiments, the separate diameter-expanding member is attached to the tip of the base member of the support shaft. However, the separate diameter-expanding member may be cylindrical and attached to the outer diameter surface of the base member. . Moreover, although the enlarged diameter part of the enlarged diameter member was formed by the taper part and the equal diameter part, this enlarged diameter part should just be a thing whose outer diameter increases monotonously in one direction, and is limited to the thing of each embodiment. There is nothing.

  Further, in each of the above-described embodiments, the number of cutting blades is six, and each of these cutting blades is urged radially inward by a tension coil spring. For example, the base end portion and the storage portion of each cutting blade By providing a spring seat in the opening of each and attaching a spring member such as a compression coil spring between the spring seats, each cutting blade can be biased radially inward. Further, the number of cutting blades is not limited to six.

DESCRIPTION OF SYMBOLS 1 Support shaft 1a Base member 1b Diameter expansion member 2 Base member 3a Sliding key 3b Key groove 4 Storage part 5 Cutting blade 5a Tip 6 Contact member 7 Through-hole 8 Tension coil spring 9a Taper part 9b Equal diameter part 10a, 10b 鍔 11a 11b Large diameter step 12 Hose 13 Swivel 14 Water supply pipe 14a Water supply holes 15a, 15b, 15c Seal ring 16 Through hole 17 Drain holes 21, 21a, 21b Manhole 22 Existing pipe line 23a Rotating towing device 23b Rotating push-in device 24 Extension rod 25 closed space

Claims (8)

It arranged a plurality of cutting blades radially around the support shaft to be inserted into the existing pipe, through the existing pipe by moving while rotating the support shaft which is disposed the cutting blade, the existing pipe In an existing pipe diameter expanding cutting tool for cutting an inner wall so as to increase the diameter of a path, a cylindrical pedestal member is prevented from rotating on the support shaft and slidably fitted in the axial direction. A plurality of storage portions opened to the outer diameter side for storing the plurality of cutting blades slidably in the radial direction and not being relatively movable in the circumferential direction are provided, and each cutting blade stored in the storage portion has a radius. Means for biasing inward in the direction, and a contact portion that protrudes from the base side of each cutting blade to the inner diameter surface of the pedestal member and contacts the outer diameter surface of the support shaft. the site of the support shaft to be contact by providing a enlarged diameter portion whose outer diameter increases monotonically in one direction, the existing pipeline to the support shaft Push during cutting moving direction or pullback direction of, and the pedestal member is slid to the large diameter side of the enlarged diameter portion to engage said abutment portion of each cutting edge on the large diameter side of the enlarged diameter portion The tip of each cutting blade housed in the housing portion is pushed outward in the radial direction, and the base member is slid to the smaller diameter side of the enlarged diameter portion when the support shaft is moved in the direction opposite to that during cutting. The abutting portion of each cutting blade is engaged with the small diameter side of the enlarged diameter portion so that the cutting blade is accommodated in the accommodating portion, and the existing pipe is expanded for diameter expansion. tool.   2. The cutting tool for increasing the diameter of an existing pipe line according to claim 1, wherein the diameter-expanded portion of the support shaft is a tapered portion whose outer diameter increases linearly. The cylindrical portion outer diameter is constant in the large diameter side of the enlarged diameter portion is provided, engages when moving the support shaft in a direction cutting is performed, the contact portion of each cutting edge to the cylindrical portion The cutting tool for expanding the diameter of an existing pipe line according to claim 1 or 2, wherein the diameter is increased.   The part of the existing pipe line according to any one of claims 1 to 3, wherein a portion of the support shaft provided with the enlarged-diameter portion is formed by a separate enlarged-diameter member, and the separate enlarged-diameter member is replaceable. Cutting tool for diameter expansion.   The means for biasing the cutting blade radially inward is a tension coil spring mounted around the abutting portion and pulling and biasing the cutting blade radially inward. A cutting tool for expanding the diameter of an existing pipe.   6. The contact member according to claim 1, wherein the contact portion is a separate contact member that is inserted into a through-hole provided in a bottom of the storage portion and connected or contacted to a base side of the cutting blade. A cutting tool for expanding the diameter of an existing pipe.   Means for supplying pressure water to the large-diameter side space of the enlarged-diameter portion in the pedestal member is provided, and the pedestal member is adjusted by the pressure water pressure supplied to the large-diameter side space of the enlarged-diameter portion. The cutting tool for expanding the diameter of an existing pipe line according to any one of claims 1 to 6, wherein the cutting tool is slid to the larger diameter side of the expanded diameter portion. The pressurized water supplied to the space of the large-diameter side of the enlarged diameter portion, in the moving direction front side of each cutting blade when moving the support shaft in a direction cutting is performed, the outer diameter side of the pedestal member 8. The cutting tool for expanding the diameter of an existing pipe line according to claim 7, wherein means for discharging is provided.

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