JPH06226547A - Pipe cutting device - Google Patents

Abstract

PURPOSE:To provide a pipe cutting device capable of cutting heat transfer tube for a steam generator or the like from its inside face through a method other than the mechanical method, coping with the usage in a narrow place and cutting not only in the circumferential direction but also in the axial direction. CONSTITUTION:The pipe cutting device is composed of cutting tools 12 and driving frame 13 while the cutting tools 12 are connected together by means of universal joint 50 capable of binding at a plural number of places and an electrode holding unit 15 is equipped with an electric discharge machining electrode 42 capable of approaching the inner surface of a pipe by protruding in the radial direction while a mounting unit 19 at the utmost rear end is equipped with a protruding part 61 on its rear end and the drive frame 13 is equipped with a rotary shaft having a groove fitting to the protruding part 61 and a moving frame 86 which rotates and moves the rotary shaft in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe cutting device,
For example, it is suitable for use when cutting the heat transfer tube of the steam generator from the inside.

[0002]

2. Description of the Related Art As one of the inspection methods for a heat transfer tube (hereinafter referred to as a tube) of a steam generator used in a nuclear power plant, there is a method of extracting the tube for inspection. That is, the tube to be inspected is cut and pulled out for inspection.

The cutting of the tube is performed by a device that inserts a tool into the tube to cut the tube from the inner surface side. An example of a conventional tube cutting tool is shown in FIGS. FIG. 10 is a cross-sectional view showing a state where the tube cutting tool is inserted into the tube, and FIG. 11 is a cross-sectional view at the time of cutting.

In FIG. 10, 201 is a sleeve forming the main body of the tool, a tip metal member 202 is attached to the tip end thereof, and a rotary shaft 204 is connected to the rear end thereof through a cylindrical joint 203. An operation shaft 205 is vertically slidably inserted in the sleeve 201, and an operation wire 206 for vertically sliding the operation shaft 205 is connected to a rear end portion of the sleeve 201. The operating wire 206 is guided to the rear operating side through the sleeve 201 and the rotary shaft 204.

In the sleeve 201, an operating shaft 205 is provided.
A pin 207 penetrating therethrough is fixed. The hole of the operation shaft 205 through which the pin 207 penetrates is a long hole 208,
The operation shaft 205 can move up and down with respect to the pin 207. The operation shaft 205 has a slit-like space 209.
Are formed, and in the pin 207,
A cutting tool 210 and a pad 211 are pivotally attached to each other in a scissor-like manner so that they can be opened and closed. Push metal parts 212 and 213 are formed on the upper part and the lower part of the space 209 of the operation shaft 205, respectively. The upper push metal part 212 serves to open the cutting tool 210 and the pad 211 when the operating shaft 205 is lowered, and the lower push metal part 213 is used when inserting the tool into the tube. It serves as a stopper so that 210 and the metal fitting 211 do not open.
Therefore, these push metal parts 212, 213 are formed in a mountain shape that matches the included angle between the cutting tool 210 and the metal fitting 211. The sleeve 201 also has a bite 21
0, a groove 217 for opening the pad 211 is formed.

Anti-sway metal fittings 214 are attached to the lower part of the sleeve 201 at four locations on its circumference. Sleeve 2
The slit 2 is provided at a portion corresponding to the steady rest 214 in 01 so that the steady rest 214 can be opened.
15 is formed. On the other hand, on the lower side of the operation shaft 205, a taper portion 216 that can be engaged with the inside of the steadying metal fitting 214 is machined on the lower side of the push metal fitting 213, and when the operating shaft 205 descends, the steadying metal fitting 216 is formed by the taper portion 216.
Is pushed open.

The cutting of the tube 220 by such a conventional tube cutting tool is performed as follows. The operation shaft 205 is pushed up by the operation wire 206, and as shown in FIG. 10, the push tool part 213 prevents the bite 210 and the pad 211 from opening, and the tool is moved to the tube 2
Insert in 20.

[0008] After the insertion to the place to be cut, the operating wire 206 is pulled to lower the operating shaft 205,
The tool 210 and the metal fitting 211 are opened by the pressing metal part 212 on the upper part of 5. The blade at the tip of the cutting tool 210 is pressed against the inner surface of the tube 220, and the metal fitting 211
The tip of the tube is also pressed against the inner surface of the tube 220. By lowering the operation shaft 205, the push metal part 213 under the operation shaft 205 is lowered.
Moves away from the bite 210 and the metal fitting 211. As the push metal part 213 descends, the taper part 216 at the lower part pushes the steadying metal part 214 open, and the tip part of the steadying metal part 214 is brought into contact with the inner surface of the tube 220.

In this state, when the rotary shaft 204 is rotated, the cutting tool 210 is swung together with the sleeve 201 to cut the tube 220 from the inner surface. Since the pad 211 and the steady rest 214 contact the inner surface of the tube 220, the bite 210 is held so as not to swing.

[0010]

However, in the conventional tube cutting tool as described above, the cutting tool 210 is used to mechanically cut and cut, so that the cutting tool 210 is extremely worn and seizure may occur. . Byte 210
If wear occurs, it is necessary to detect it and replace it. However, in order to detect it, it is necessary for a skilled worker to work in the water chamber (tension and relaxation of the wire). There are restrictions on radiation control. There is also a problem that the tool structure is limited to cutting the straight pipe in the circumferential direction.

[0011]

The structure of a tube cutting device according to the present invention which solves the above problems comprises a cutting tool to be inserted into a pipe and a drive table attached to the outside of the pipe. It has an electrode holding part in which a discharge machining electrode is provided so as to be able to project and retract in the radial direction, and a plurality of elastic materials which are coupled to the tip end side in the axial direction of the electrode holding part and elastically contact the inner surface of the tube A tip-shaped holding portion, a shaft-shaped mounting portion located at the rearmost portion and having a driving force transmission portion at the rear end, and a plurality of members provided between the electrode holding portion and the mounting portion and contacting the inner surface of the tube. One or more intermediate joints having one elastic holding member and one universal joint at one end for connecting to another portion, and one or more intermediate joints having a mechanism for restraining or releasing the universal joint And the drive base is on the pipe end side. A drive base main body to be fixed, a rotary shaft supported by the drive base main body and connected to a drive force transmitting portion of an attachment portion of the cutting tool, and a drive mechanism for rotating and rotating the rotary shaft in the axial direction. It is characterized by being prepared.

[0012]

When the cutting tool is inserted into the pipe, the electric discharge machining electrode in the electrode holding portion is housed in the tubular body and inserted into the pipe without any trouble. At the portion of the tube to be cut, the electrode for electric discharge machining in the electrode holding portion is projected from the cylindrical body and is brought close to the inner surface of the tube. In this state, the pipe is filled with the machining fluid, and an electric discharge is made between the electric discharge machining electrode and the inner surface of the pipe.
Electric discharge machining is performed. When the rotating shaft of the drive table is rotated by the drive mechanism, the electric discharge machining electrode is rotated together with the electrode holding portion, etc., and cutting is performed by electric discharge machining in the circumferential direction of the tube. Also, the pipe can be cut in the axial direction by moving the cutting tool up and down by the drive mechanism of the drive table. Prior to the insertion into the pipe, the universal joint of the intermediate joint portion of the cutting tool is released, so that the insertion into the pipe is possible even in a narrow environment.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the pipe cutting device according to the present invention will be described with reference to the drawings. In the drawings, FIG. 1 is a side view and an end view of the entire cutting tool of the pipe cutting device, FIGS. 2 to 4 are cross-sectional views of respective portions of the cutting tool, and FIGS. 5 to 8 are pipe cutting devices. FIG. 9 is a cross-sectional view of the drive base of FIG. 9, and FIG. 9 is a schematic cross-sectional view of the tube cutting device in use.

The tube cutting apparatus according to this embodiment is applied to cutting the tube 2 of the steam generator 1 as shown in FIG. In the steam generator 1, 3 is a tube plate to which the tube 2 is attached, 4 is a water chamber below the tube plate 3, and 5 is a manhole communicating with the water chamber 4.

The pipe cutting device 11 comprises a cutting tool 12 and a drive base 13. As shown in FIG. 1, the cutting tool 12 in the device of this embodiment includes a tip holding portion 14, an electrode holding portion 15, a first intermediate joint portion 16, an intermediate holding portion 17, a second intermediate joint portion 18, and a mounting portion 19. It is configured by connecting in order.

FIG. 2A showing a vertical cross section of the tip holding portion 14.
In the figure, 20 is a cylindrical shaft, and a conical metal fitting 21 is attached to the tip thereof. An annular convex portion 22 is formed on the rear portion of the shaft 20, and the convex portion 22 and the metal fitting 21 are formed.
An inner cylinder 25 is provided between the and, via sleeves 23 and 24. Two grooves 26 are formed on the outer circumference of the inner cylinder 25 along the axial direction.
As shown in (A) and (B), a stabilizer 27 is provided, which is formed by forming a thin elastic strip plate into a mountain shape. An outer cylinder 28 for holding both ends of the stabilizer 27 is attached to the outer side of the inner cylinder 25.

When the cutting tool 12 is inserted into the tube 2, the stabilizer 27 of the tip holding portion 14 elastically contacts the inner surface of the tube 2 and holds the electrode holding portion 15 inside the tube 2. The constituent members of the tip holding portion 14 are made of metal such as stainless steel. The electrode holder 15 is connected to the rear end of the shaft 20 of the tip holder 14 via a joint 29.

FIG. 3 (A) shows a vertical section of the electrode holding portion 15, and FIG. 3 (B) shows a section taken along the line C--C. A motor 31 is incorporated in a cylindrical motor case 30 that is connected to the joint 29. A bearing case 32 made of an insulating material is coupled to an end of the motor case 30, and a drive shaft 34 connected to a rotating shaft 33 of the motor 31 is supported in the bearing case 32. A screw portion 35 is formed on the drive shaft 34.

A guide cylinder 35 is coupled to the bearing case 32, and an insulating cylinder 36 covers the outside thereof. A slide nut 38 which is non-rotatable and slidable in the axial direction is provided in the guide cylinder 37, and a screw portion 35 of the drive shaft 34 is screwed into the slide nut 38. A link 39 is connected to the slide nut 38.

On the other hand, the electrode guide 40 is provided in the guide cylinder 35.
Is assembled, and an electric discharge machining electrode (hereinafter referred to as an electrode) is provided in a guide groove 41 formed in the electrode guide 40.
42 is accommodated, the end of which is on the side of the guide cylinder 37 is rotatably fastened to the electrode guide 40 by a pin 43, and is connected to the link 39 by a pin 44.

Therefore, when the slide nut 38 is moved in the axial direction by the drive of the motor 31, the electrode 42 is rotated about the pin 43 via the link 39, and the insulating cylinder 36 is shown by the arrow in the figure. It projects further or is housed in the insulating cylinder 36. Of course, the insulating cylinder 36 is formed with a groove 45 through which the electrode 42 comes in and out.

An elastic band 46 is stretched between the electrode 42 and the electrode guide 40, and the electrode 42 is always provided with a direction to be drawn into the insulating cylinder 36.
Rattling is kept to a minimum. Electrode guide 4
A lead wire for power feeding is connected to 0, and power is fed to the electrode 42 via the electrode guide 40. Since the main electrode holder 15 is cut from the inside of the object to be cut (small-diameter tube), the insulating cylinder 36 maintains insulation between the object to be cut and the guide cylinder 37 and the electrode guide 40. The lead wire is guided to the outside of the device through the intermediate joint portion 16, the intermediate holding portion 17, and the like.

The maximum notch of the electrode 42 and the storage in the insulating cylinder 36 are detected by an electric contact (not shown). The lead wire of the electrical contact is the motor 3
With the first lead wire, as shown in FIG. 3B, the lead wire is guided rearward through the gap on the side surface of the electrode guide 40. In the figure,
47 is a lead wire.

Since the cutting tool 12 is used in the working fluid, the cutting tool 12 is provided between the joint 29 and the motor case 30 and between the drive shaft 34 and the bearing case 32 so that the motor 31 in the electrode holding portion 15 is not flooded. Each has an O-ring 48
Is provided.

A joint 49 made of an insulating material is joined to the rear end of the insulating cylinder 36 of the electrode holding portion 15.
As shown in FIG. 4, the joint member 51 of the universal joint 50 at the end of the first intermediate joint portion 16 is joined. The other joint member 52 of the universal joint 50 is integrally connected to the tip of a tubular joint shaft 53. A cylindrical extension shaft 54 is coupled to the rear end of the joint shaft 53.

A slide cylinder 55 is slidably fitted on the outer side of the joint shaft 53. At the end of the slide cylinder 55, a fixing fitting 56 that can be fitted to the outer periphery of the joint member 51.
Is installed. As shown in FIG. 4C, the slide cylinder 55 is formed with an L-shaped groove 57, and the joint shaft 53 is provided with a pin 58 that fits into the groove 57.

Therefore, the slide cylinder 55 can move in the axial direction and the circumferential direction through the engagement between the groove 57 and the pin 58. That is, in the state of FIG. 4 (A), the fixing metal fitting 56 attached to the end of the slide cylinder 54 is fitted to the joint member 51 of the universal joint 50 to fix or restrain the universal joint 50, Although the intermediate joint part 16 acts as a simple intermediate shaft, as shown by the broken line in FIG. 4A, when the fixing metal fitting 56 is displaced rearward together with the slide cylinder 55, the fixing metal fitting 56 is formed. Is a joint member 51
Is released, that is, the restraint of the universal joint 50 is released, and the flexible joint 50 is ready to be bent.

A spring 59 having a four-leaf cross section is provided between the slide cylinder 55 and the joint shaft 53, as shown in FIG. 4 (B). This spring 59
Serves to prevent the slide cylinder 55 from freely rotating.

An intermediate holding portion 17 is connected to the rear end of the first intermediate joint portion 16 via a joint 60. The joint 60 is
It is the same as the joint 29 that connects the tip holding portion 14 and the electrode holding portion 15 described above. The intermediate holding portion 17 has the same structure as the tip holding portion 14 except for the metal fitting 21 at the tip of the tip holding portion 14. At the rear end of the intermediate holding portion 17, the first
The second intermediate joint portion 18 having the same structure as the intermediate joint portion 18 is connected.

A mounting portion 19 having a structure similar to that of the first intermediate joint portion 16 is connected to a rear end of the second intermediate joint portion 18. As shown in FIGS. 1A and 1B, a cross-shaped protrusion 61 is formed as a driving force transmitting portion at the rear end of the mounting portion 19.

The total length of the cutting tool 12 thus constructed is adjusted by changing the number and length of the intermediate joints 16 and 18 according to the cut portion of the tube 2.

As shown in FIG. 6, brackets 72 are provided on both upper sides of a casing 71 which is the main body of the drive table of the drive table 13.
A clamp cylinder 73 is attached via. The clamp cylinder 73 expands and contracts the clamp member 74 inserted into the tube 2 other than the tube 2 to be cut, and fixes or releases the clamp member 74 with respect to the tube 2. Clamp member 74 is tube 2
The drive base 2 is fixed by being expanded inside.

As shown in FIG. 5, the casing 71 is provided with an inner box 75. The inner box 75 has a drive base 1
The guide pipe 76 is attached so as to be located on the extension of the tube 2 to be cut when the tube 3 is fixed at a predetermined position. The upper portion of the guide pipe 76 has a cover 78 and a seal 79 attached to the top plate 77 of the casing 71.
It is covered with. The seal 79 seals the gap with the tube sheet 3. A drain receiver 80 is attached to the upper portion of the guide pipe 76 and below the top plate 77 of the casing 71. A drain pipe 81 is connected to the drain receiver 80 so that drain water (processing liquid) can be discharged and collected outside the machine via a hose or the like. An O-ring 82 is provided between the drain receiver 80 and the guide pipe 76.

In the casing 71, a ball screw shaft 83 parallel to the guide pipe 76, that is, parallel to the vertical direction in FIG. 5, is rotatably supported at its upper and lower ends by bearings 84 and 85. The moving table 8 is attached to the ball screw shaft 83.
A ball nut unit 87 integral with 6 is screwed. As shown in FIG. 7, linear guide members 88a extending vertically are attached to both side surfaces of the moving base 86, and these linear guide members 88a are fitted to linear guide members 88b provided on the casing 71 side. And the linear guide 88 is configured. The linear guide 88 guides the movable table 86 in the vertical movement.

A bearing box 89 is attached to the movable table 86, and a rotating shaft 90 is rotatably supported by a bearing 91 on the bearing box 89 coaxially with the guide pipe 76. A gear 92 is fixed to the upper portion of the rotary shaft 90, and the drive gear 9 supported in a bearing box 89 is fixed to the gear 92.
3 is meshed. The drive gear 93 includes a bearing box 8
A drive shaft 95 of a motor 94 mounted in the motor 9 is connected. Further, the drive gear 93 is connected to the rotary encoder 97 via the gear 96.

Therefore, the rotating shaft 90 is driven and rotated through the gears 92 and 93 by driving the motor 94, and the number of rotations thereof is measured by the rotary encoder 97.

At the lower end of the rotary shaft 90, I- in FIG.
As shown in FIG. 8B, which is a cross section taken along the arrow I, a cross-shaped groove 98 is formed, and the cross-shaped projection 61 of the attachment portion 19 located at the rearmost portion of the cutting tool 12 is formed therein. It is designed to fit. After the protrusion 61 is fitted in the groove 98, the cap 99 is attached.

On the other hand, a gear 100 is fixed to the upper portion of the ball screw shaft 83, and a drive gear 101 is meshed with the gear 100. The drive gear 101 has
Support frame 102 attached to the top plate 77 of the casing 71
The drive shaft 104 of the motor 103 supported by is connected. Further, the drive gear 101 is connected to the rotary encoder 106 via the gear 105.

Therefore, the ball screw shaft 83 is rotated by the drive of the motor 103 via the gears 100 and 101,
The moving table 86 moves up and down along the ball screw shaft 83. In addition, the rotary encoder 106 allows the ball screw shaft 8
A rotational speed of 3 is detected.

Next, the cutting operation of the tube 2 by the apparatus of this embodiment will be described. First, the drive base 13 is fixed to the tube sheet 3. The drive table 13 is positioned by the operation of the manipulator from the water chamber 4 so that the guide pipe 76 is located immediately below the tube 2 to be cut, and the clamp member 74 is inserted into the adjacent tube 2. . In this state, the clamp cylinder 73 is operated,
The drive base 13 is fixed by the clamp member 74 being expanded and fixed so as to be stretched in the tube 2.

On the other hand, the cutting tool 12 has a symbol "J" in FIG.
The total length is determined according to the cutting position of the tube 2 indicated by. As described above, the adjustment of the tool length is performed by the intermediate joint portions 16 and 18
This is done by changing the number of and the length. Also,
Since the inside of the water chamber 4 is narrow, the restraint of the universal joint 50 in each of the intermediate joint portions 16 and 18 is released so that it can be bent freely.

The cap 99 at the lower end of the rotary shaft 90 of the drive table 13 is removed, and the cutting tool 12 in a continuous state as shown in FIG. To go. The electrode 42 in the electrode holding portion 15 has an insulating cylinder 36 as shown by a broken line in FIG.
It should be stored inside. In addition, each intermediate joint 1
The slide cylinders 55 of 6 and 18 are displaced to the front side and the universal joint 50 is restrained and inserted. The rotary shaft 90
Is held at the uppermost position as shown in FIG.

The cross-shaped projection 61 at the rear end of the mounting portion 19 is fitted into the cross-shaped groove 98 at the lower end of the rotating shaft 90, and the rotating shaft 90
A cap 99 is attached and held at the rear end.

This completes the attachment of the cutting tool 12 to the drive table 13. The cutting tool 12 is collected in the reverse order of the above.

As described above, the cutting tool 1 is placed in the tube 2.
After inserting 2, water is injected into the tube 2 from the opposite side of the tube 2 as a working fluid.

Next, the motor 31 of the electrode holder 15 is driven to drive the electrode 42 through the slide nut 58 and the link 39.
Is projected in the radial direction as shown by the solid line in FIG. 3 (A), and its tip is brought close to the inner surface of the tube 2.

In this state, the electrode 42 is energized to cause discharge between the tip of the electrode and the inner surface of the tube 2,
Start cutting on the inner surface.

Then, the motor 94 of the drive table 13 is driven to rotate the cutting tool 12 together with the rotary shaft 90, and the electrode 4
2 is moved in the circumferential direction of the tube 2 to cut the entire circumference.

When the cutting in the circumferential direction is completed, the motor 10
3 is driven to lower the moving table 86 to cut the tube 2 in the vertical direction. During the cutting process, water is continuously poured into the tube 2 and the water that has flowed down enters the drain receiver 80 of the drive table 13 and is discharged from there through the discharge pipe 81.

When the cutting in the vertical direction is completed, the electrode 42 is housed in the insulating cylinder 36, the power is turned off, and the water injection into the tube 2 is stopped. The above operation is performed by remote control.

After cutting the tube 2 and recovering or retracting the cutting tool 12 and the drive base 13, the welded portion between the tube 2 and the tube sheet 3 is removed, and the cut tube 2 is removed by a tube removing device. Remove from 3.

The above-mentioned embodiment is an example in which the present invention is used for cutting the tube 2 of the steam generator, but the apparatus according to the present invention can be used for general cutting from inside the thin tube.

In the above embodiment, the slide nut 38 is used as the means for inserting and removing the electrode 42 in the electrode holding portion 15,
Although the link 39 or the like is adopted to move in and out by turning, the moving in / out means is not limited to this, and may be moved in and out by radial movement, for example. Further, as a mechanism for restraining and releasing the universal joint 50 in the intermediate joint portions 16 and 18, various mechanisms such as a mechanism for restraining the joint member 51 from the inside can be adopted. Further, the mounting portion 19 and the rotating shaft 9
The driving force transmitting portion for coupling with 0 is not limited to the combination of the cross-shaped protrusion portion 61 and the groove 98, and other fitting shapes and structures can be adopted.

[0054]

According to the pipe cutting apparatus of the present invention, since the cutting is performed by electric discharge machining, the cutting tool is not subjected to mechanical reaction force and is easy to operate. There is no worry about seizure.

Since the electrode holding portion of the cutting tool is supported inside the tube by the holding portions before and after the electrode holding portion, the electric discharge machining electrode is held in the tube without rattling, and the cutting start point and the cutting end point are not displaced. .

Since the universal joint in the intermediate joint portion of the cutting tool is constrained or released, when the universal joint is released and can be bent freely, it is easy to handle in a narrow place and restrained. In this case, the torque can be transmitted without any trouble.

Further, since the cutting tool can be moved not only by rotation but also in the axial direction by the drive table, it has become possible to cut the pipe in the axial direction, which could not be done conventionally.

[Brief description of drawings]

FIG. 1A is a side view of a cutting tool of a pipe cutting device according to an embodiment, and FIG. 1B is an end view taken along the line AA of FIG.

FIG. 2A is a sectional view of a tip holding portion, and FIG. 2B is a sectional view taken along the line BB.

3A is a cross-sectional view of an electrode holding portion, and FIG. 3B is a cross-sectional view taken along the line CC of FIG.

FIG. 4A is a sectional view of a first intermediate joint portion,
(B) is the DD sectional view taken on the line, (C) is an EE arrow sectional view.

FIG. 5 is a vertical cross-sectional view of a drive table of the tube cutting device according to one embodiment.

6 is a cross-sectional view taken along the line FF in FIG.

FIG. 7 is a sectional view taken along the line GG in FIG.

8 (A) is a sectional view taken along the line H-H in FIG.
(B) is the II sectional view taken on the line.

FIG. 9 is a schematic cross-sectional view of a pipe cutting device according to one embodiment in use.

FIG. 10 is a cross-sectional view of an example of a conventional pipe cutting tool.

FIG. 11 is a cross-sectional view of a conventional tool in use.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam generator 2 Tube 3 Tube plate 4 Water chamber 11 Tube cutting device 12 Cutting tool 13 Drive stand 14 Tip holding part 15 Electrode holding part 16 First intermediate joint part 17 Intermediate holding part 18 Second intermediate joint part 19 Mounting part 27 Stabilizer 31 Motor 39 Link 42 Electric discharge machining electrode 50 Universal joint 54 Slide cylinder 56 Fixing metal fitting 61 Protrusion 71 Casing 73 Clamp cylinder 76 Guide pipe 86 Moving base 90 Rotating shaft 98 Groove

Claims (1)

[Claims] 1. An electrode holding part comprising a cutting tool inserted into a tube and a drive table attached to the outside of the tube, wherein the cutting tool is provided with an electrode for electric discharge machining provided in a cylindrical body so as to be capable of projecting and retracting in the radial direction. And a tip holding portion having a plurality of elastic members that are coupled to the tip end side in the axial direction of the electrode holding portion and elastically contact the inner surface of the tube, and a driving force transmission portion located at the rear end and at the rear end. A shaft-shaped mounting part having
One or a plurality of intermediate holding portions provided between the electrode holding portion and the mounting portion and having a plurality of elastic members that come into contact with the inner surface of the tube, and a universal joint at one end for connecting with another portion. And one or more intermediate joint portions having a mechanism for restraining or releasing the universal joint, the drive base being a drive base main body fixed to a pipe end side, and the drive base main body. A tube cutting device, comprising: a rotary shaft supported by a rotary shaft connected to a drive force transmission part of a mounting part of the cutting tool; and a drive mechanism for rotating and rotating the rotary shaft in an axial direction.