KR100390088B1 - Steel Pipe Cutting Device - Google Patents

Abstract

(Problem) Provide a steel pipe cutting device that can cut the poured steel pipe mechanically from the inside.

(Measures) The cutter 4 is suspended through the connecting shaft 3 on the rotary shaft 2 of the drive mechanism 1 which is mounted on the steel pipe and fixed, and the cutter 4 is installed at the tip of the frame 31. The blade 32 is pressed against the inner circumferential surface of the steel pipe A by opening and dropping the blade 32 and the reaction roller 42 at the rear with a hydraulic cylinder to rotate the cutter 4 by the motor of the drive mechanism 1. Push the steel pipe (A) with

Description

Steel Pipe Cutting Device

The present invention relates to a steel pipe cutting device for cutting and removing steel pipes placed in groundwater or water from the inside thereof.

(Conventional technology)

For example, in the steel pipe shaft after pouring, the part protruding in the water is obstructed by the water channel, so it should be cut off. The use of a mechanical cutting device is suitable for cutting poured steel pipes.

Mechanical steel pipe cutting device is composed of a drive mechanism installed on the upper end of the steel pipe to be cut, and a cutter for connecting the rotary shaft of the drive mechanism through a connecting shaft to rotate in the steel pipe, the cutter can rotate the blade in front of the frame The reaction roller is mounted on the rear end of the frame through the link mechanism, and the advanced blade is pushed on the inner circumferential surface of the steel pipe by pressing the inner circumferential surface of the steel pipe with the reaction roller in the hydraulic cylinder installed on the frame. In order to cut the steel pipe with a blade by rotating the entire stage.

However, when the hydraulic cylinder is used for the cutting machine, it is necessary to install hydraulic pipes along the connecting shaft between the drive mechanism and the cutting machine. When the number of these pipes increases, the operation of the cutting device for the steel pipe is disturbed or complicated. Therefore, it is better to use one pipe for the hydraulic cylinder.

Conventionally used single-acting hydraulic cylinders incorporate a double acting spring into a cylinder, and the cylinder extends by hydraulic pressure and contracts by a spring force.

In addition, the steel pipe cutting device fixes the driving mechanism installed on the steel pipe to the steel pipe while the rotation axis thereof is coaxial with the steel pipe, and secures the steel pipe to the driving mechanism by the hydraulic cylinder so as not to rotate with the cutter. Although a supporting chuck mechanism is provided, the hydraulic cylinder of the conventional chuck mechanism is suppressed by an independent hydraulic circuit.

First, since the single-acting hydraulic cylinder used in the conventional cutting machine has a structure in which a spring is assembled therein, the sealing property of the expansion and contraction end of the piston becomes insufficient, and this hydraulic cylinder is used in sewage, There is a problem that infiltration of sewage into the cylinder occurs and the durability of the cylinder is low.

Next, the method of independently controlling the chuck mechanism for fixing the driving mechanism to the steel pipe irrespective of the driving mechanism or the cutting machine has a problem that the operation of the cutting device is complicated.

In addition, since the placed steel pipe has various diameters and the cutting position changes in the field, the cutting device can change the cutting diameter and change the cutting depth position in response to the diameter change of the steel pipe to be cut. Function is required.

Accordingly, an object of the present invention is to provide a steel pipe cutting device that is excellent in the durability of the hydraulic cylinder of the cutter and the control of the chuck mechanism for fixing the drive mechanism can be easily performed, and the cutting diameter and the cutting depth position can be changed. have.

(Means to solve the task)

In order to solve the above problems, the invention of claim 1 is made of a drive mechanism installed on the upper end of the steel pipe to be cut, and a cutter for connecting to the rotary shaft of the drive mechanism via a connecting shaft to rotate in the steel pipe, The cutter is rotatably attached to the front end of the frame and presses the blade against the steel pipe by cutting the roller against the inner circumferential surface of the steel pipe with a cylinder installed on the frame to the rear end of the frame through a link mechanism. In the formed steel pipe cutting device,

A hydraulic cylinder is used as the cylinder of the cutter, and the hydraulic supply pipe is connected to one of the two rooms in the cylinder body partitioned with a piston to extend the hydraulic cylinder, while the hydraulic pipe is connected to the other room to deflate the hydraulic cylinder. The accumulator is connected via the configuration.

According to the invention of claim 2, the cutter is configured to support the blade freely with the support block, and to replace the support block with the support unit installed at the front end of the frame.

According to the invention of claim 3, an attachment plate is provided on the upper part of the frame of the cutter, and a rectangular plate fixed to the lower end of the attachment axis of the connecting shaft is overlapped on the attachment plate so as to be freely moved forward and backward along guides provided on both sides of the attachment plate. By connecting the plurality of adjustment holes provided in the front and rear direction of the mounting plate and the bolt holes of the square plate with bolts, the connection position between the frame of the cutter and the connecting shaft where the mounting plate and the square plate contact each other is horizontal. The configuration is variable in the direction.

The invention of Claims 4 and 6 sets it as the structure which the connection of the frame of a cutter and a connecting shaft can be adjusted up and down by a telescopic joint.

According to the inventions of claims 5 and 7-9, the drive mechanism is provided with an insertion part into the steel pipe at the lower part of the casing, and interlocks a rotating shaft provided in the insertion part with a motor installed on the casing, and the steel pipe outside the insertion part. And a chuck mechanism for firmly supporting the circumferential wall of the cylinder with a cylinder. The cylinder of the chuck mechanism and the cylinder of the cutter are connected to a common hydraulic supply source, and the check valve is connected to the cylinder of the chuck mechanism. The on-off valves are provided in parallel, the motor and the closing valve are electrically connected to each other, and the chuck mechanism is configured to allow the cylinder to contract by turning off and on the motor.

1 is a longitudinal sectional view showing the set state of the steel pipe cutting device to the steel pipe,

2 is an enlarged longitudinal cross-sectional view showing a drive mechanism portion of the steel pipe cutting device of FIG.

3 is a bottom view according to arrow III-III of FIG. 2,

4 is a perspective view of a drive mechanism,

5 is a longitudinal cross-sectional view of the cutter,

6 is a cross section according to arrow VI-VI of FIG. 5,

7 shows a cross section according to arrow VII-VII of FIG. 5,

8 is a cross-sectional view according to arrows VIII-VIII of FIG. 5,

9 is a perspective view of the cutter,

(A) is a longitudinal cross-sectional view which shows the part of the elastic joint which connects a cutter and a connection shaft, (B) is a longitudinal cross-sectional view,

11 is a circuit diagram showing a hydraulic circuit.

Explanation of symbols on the main parts of the drawings

1: driving mechanism 2: rotating shaft 3: connecting shaft

4: cutter 6: electric motor 8: cylindrical body

11: mounting plate 12: centering mechanism 13: chuck mechanism

23 two-prong bracket 25 hydraulic cylinder 31 frame

32: blade 33: hydraulic cylinder 37: parallel four-sided link

39: moving member 40: connecting bar 42: reaction roller

43: support block 44: housing 54: accumulator

76: hydraulic source 79: check valve 80: on-off valve

A: steel pipe

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with an illustration example.

1 shows the overall structure of a cutting device for cutting the poured steel pipe A. The cutting device includes a drive mechanism 1 mounted on and fixed to an upper end of the steel pipe A, and the drive mechanism 1 And a plurality of coupling shafts 3 connected to the rotary shaft 2 of the crankshaft, and a cutter 4 attached to the lower end of the coupling shaft 3.

The driving mechanism 1 fixes the electric motor 6 at one end position on the upper surface of the box 5 which can be suspended by a crane or the like as shown in FIGS. The rotating shaft 2 which fixed the cylindrical body 8 inserted in the steel pipe A in the lower surface of the support leg 7 and the other end, and was installed in the cylindrical body 8 so that it might be coaxial. The output shaft 9 of the motor 6 is interlocked with the sprocket positioned in the box 5 and the chain 10, and the upper end surface of the steel pipe A is positioned at the outer circumference at the upper and lower middle portions of the cylindrical body 8. The placement plate 11 against is fixed horizontally.

A plurality of centering mechanisms 12 are provided on the mounting plate 11 so as to surround the lower outer periphery of the cylindrical body 8, and the driving mechanism 1 is attached to the steel pipe A on the lower surface of the box 5. The chuck mechanism 13 is fixed to be fixed.

As shown in FIGS. 2 to 4, the centering mechanism 12 pivots a lower end with a hinge 14 on the lower outer circumferential surface of the cylindrical body 8, so that swinging in the radial direction of the cylindrical body 8 is free. Adjusting screw shaft that horizontally penetrates the upper end of the regulation bar 15 arranged so as to penetrate the long hole 16 provided in the mounting plate 11 and penetrate horizontally through the bracket 17 installed on the outer periphery on the mounting plate 11. The tip of (18) is connected to the regulation bar 15 through the joint box 19, and the spring 20 which presses the regulation bar 15 toward the cylindrical body 8 on the screw shaft 18 is built up. The nut 21 is screwed into the rear end of the screw shaft 18.

The centering mechanism 12 changes the arrangement diameter of the regulation bar 15 by the rotation operation of the nut 21, and adjusts the arrangement diameter to the inner diameter of the steel pipe A to cut the arrangement diameter. Is set on the steel pipe A, the control bar 15 group fits into the steel pipe A, and makes the rotation shaft 2 arrange | position coaxially with the steel pipe A. As shown to FIG.

The chuck mechanism 13 suspends the bifurcation bracket 23 on the hinge 22 fixed to the lower surface of the box 5 so that the swing and the up and down movement can be freely through the link 24. On the outer surface of 23), the outer surface of the steel pipe A is pressed, a hydraulic cylinder 25 for fitting the circumferential wall of the steel pipe A into the two brackets 23 is provided, and driven against the steel pipe A. The mechanism 1 is fixed to the rotation stop state.

The chuck mechanism 13 is located between the adjacent centering mechanisms 12, and the two brackets 23 are accommodated in the radial notch portion 26 provided on the mounting plate 11, and the two brackets are provided. The bracket 23 is free to swing only in the radial direction of the cylindrical body 8.

When the drive mechanism 1 is placed on the steel pipe A, the bifurcated bracket 23 is fitted with the lower concave cutout 27 outward with respect to the circumferential wall of the steel pipe A, and the radial fluctuations in the radial direction are caused. This makes it possible to cope with a change in the diameter of the steel pipe A.

The connecting shaft 3 connected to the rotation shaft 2 of the drive mechanism 1 is prepared in two kinds of different lengths, and as shown in FIG. 2, the cylindrical portion 28 at one end and the angular shaft at the other end ( 29), by connecting the fitting portion of the angular cylindrical portion 28 and the angular shaft 29 with the pin 30, the connection with the rotary shaft 2 and the connecting shaft 3 are joined, thereby connecting the connecting shaft 3 By the combination of the number of connection and the long and short, the length of the cutter 4 to the cutting position.

As shown in FIGS. 5 to 9, the cutting tool 4 is freely rotatably attached to the blade 32 horizontally to the front end of the frame 31 accommodated in the steel pipe A. The hydraulic cylinder 33 is accommodated inside the 31 and at the same time, the upper edge or the lower edge of the frame 31 is placed at a symmetrical position with the horizontal axis of the hydraulic cylinder 33 interposed between the upper and lower sides of the frame 31. The parallel four-sided link 37 which consists of a side link, the horizontal link 36 which connects the front-end link 34 and the rear link 35, and the front end of the all-link 34 and the rear link 35 mutually is provided. It is.

At the rear of the frame 31, a moving member 39 is supported, which is freely supported by the concave cutout portion 38 installed in the frame 31, and is provided with the hydraulic cylinder 33. All the links 34 and 34 positioned up and down with the movable member 39 are connected through the connecting bars 40 and 40, and are moved back and forth by the movable member 39 by the expansion and contraction of the hydraulic cylinder 33. The horizontal links 36 and 36 are configured to move back and forth.

A pair of upper and lower brackets 41 extending from both sides are fixed to the rear ends of the horizontal links 36 and 36, respectively, and horizontal reaction rollers 42 are rotatably attached to both ends of the brackets 41, respectively. .

The blade 32 is horizontally supported freely rotated by the support block 43, the support block 43 is freely fitted and removed in the receiving portion 44 installed on the front end of the frame 31, the support block 44 and the blade 32 are replaceable with respect to the frame 31.

Support arms 45 and 45 protruding upward on both sides of the frame 31 are fixed, and horizontal attachment plates 46 are fixed between the upper ends of both support arms 45 and 45.

As shown in FIG. 7, the hydraulic cylinder 33 of the cutter 4 is provided with a rod 49 protruding rearward from the piston 48 in which the sliding motion is freely accommodated inside the cylinder body 47. While screwing the rear end of the rod 49 with the movable member 39, the rear end of the cylinder body 47 is hermetically sealed to the rod 49 by a bush 50 which is fitted outwardly in a watertight state, and is fitted. The seals installed on the part and the sliding part prevent the inflow of sewage.

In the two chambers 51 and 52 in the cylinder body 47 partitioned by the piston 48, a hydraulic supply pipe 53 is connected to one chamber 51 for extending movement and the other chamber for contracting. The accumulator 54 attached to the predetermined position, such as the outer surface of the support arm 45, is connected to the chamber 52 of the chamber 52 via the connection pipe 55. As shown in FIG.

Therefore, the hydraulic cylinder 33 retracts the reaction rollers 42 and 42 by pushing the piston 48 to which hydraulic pressure is supplied to one chamber 51 to the rear, and pushing the moving member 39 to the rear. It comes in contact with the inner circumferential surface of the steel pipe A.

In addition, the accumulator 54 accumulates the hydraulic pressure in the chamber 52 pressurized by the retraction of the piston 48, and when the hydraulic pressure of the one chamber 51 is released, the accumulator 54 is discharged to the other chamber 52. By supplying hydraulic pressure, the piston 48 is advanced to contract the hydraulic cylinder 33.

8 and 10 illustrate a structure in which the cutter 4 is attached to the lower end of the connecting shaft 3, and the flange 57 is circumferentially attached to the upper end of the attaching shaft 56 installed on the attaching plate 46. And the annular plate 59 is inserted outwardly so as to be movable up and down on the intermediate shaft 58 mounted on the attachment shaft 56 so as to be coaxial. The annular plate 59 and the flanges 57 Coupled with the bolt 60, the spring 62 is laid between the annular plate 59 and the lower flange 61 of the intermediate shaft 58, the cutting machine 4 on the intermediate shaft 58 spring 62 It is attached in the form of hanging through), and when hanging, a gap is formed between the lower end of the intermediate shaft 58 and the flange 57 as shown in FIG. 10 (A), thereby allowing the vertical movement of the cutter 4. have.

10 (A) and (B) show the expansion joint connecting the connecting shaft 3 and the cutting machine 4, and each axis 63 and 63a having a predetermined length is disposed at the upper and lower ends of the intermediate shaft 58. As shown in FIG. The inner diameter of the connecting shaft 3a to be used at the lowermost position is an angular hole where the upper angular axis 63 is fitted, and the lower angular axis 63a is freely fitted with the angular hole in the attachment shaft 56. It is aligned. The upper and lower shafts 63 are provided with the adjusting holes 64 at regular intervals in the vertical direction, and at the same time, the bolt holes 65 are provided at the upper and lower ends of the lowermost connecting shaft 3a by 1.5 times as large as the adjusting holes 64. The shafts 63 and the lowermost connecting shaft 3a are engaged by the coupling between the bolt holes 65 and the bolts 66 inserted through the adjustment holes 64, and the upper and lower parts of the cutter 4 are installed. The position is made variable by the pitch of 1/2 of the adjustment hole 64. As shown in FIG.

In addition, as for the coupling of the attachment plate 46 and the attachment shaft 56 in the cutter 4, as shown in FIG. 8, the square plate 67 fixed to the lower end of the attachment shaft 56 on the attachment plate 46 is shown. The plurality of adjustment holes 69 and the square plate 67 overlapping with each other in the front and rear directions of the mounting plate 46 so as to move freely along the guides 68 provided on both sides of the mounting plate 46. By coupling the bolt holes 70 of the blades) with the bolts 71, the front and rear positions of the cutters 4 are varied at intervals of the adjustment holes 69 with respect to the shaft center of the connecting shaft 3, and the cutting of the blades 32 is performed. The change of the diameter of the steel pipe A to cut | disconnect a radius is made to respond | correspond.

In addition, in order to make the cutting diameter variable, the front and rear lengths are different from the block 43 pivoting the blade 32, and the block 43 attaches the blade 32 to the frame 31 by the block 43. Alternatively, the block 43 may be changed back and forth, or the block 43 may be shortest in front and rear length so that a spacer having a different thickness is interposed between the block 43 and the inner end of the housing 44 to replace the spacer 32. You can freely adjust back and forth.

In order to supply the hydraulic pressure to the hydraulic cylinder 33 of the cutter 4, as shown in FIGS. 1 and 2, the swivel joint 72 is coaxially installed on the upper end of the rotating shaft 2 of the drive mechanism. An upper end of the rotary shaft 2 communicates with the joint, and a passage 73 is formed in which the lower end is opened on the intermediate outer circumferential surface of the rotary shaft 2, and the lower end of the passage 73 and the supply pipe of the hydraulic cylinder 33 described above. (53) is connected by a conduit (74) along the outer surface of the connecting shaft (3).

11 shows a hydraulic circuit for controlling the hydraulic cylinder 25 of the chuck mechanism 13 and the hydraulic cylinder 33 of the cutting machine 4 installed in the drive mechanism 1, and having a hydraulic pump 75. The hydraulic pressure supply port of the hydraulic pressure source 76 and the swivel joint 72 are connected to the conduit 77, and the hydraulic pressure supply to the hydraulic cylinder 33 is performed by the manual switching valve 78, and at the same time, the conduit 77 In the middle of the conduit connecting the hydraulic cylinder 25 of the chuck mechanism 13 and the check valve 79 and the two-way roller opening / closing valve 80 are assembled in parallel, and the hydraulic cylinder Supply is performed through the check valve 79, and discharge | release of hydraulic pressure is performed by opening the on-off valve 80. FIG.

The on-off valve 80 is electrically interlocked with the motor 6 of the drive mechanism 1 so that the on-off valve 80 is closed when the power to the motor 6 is turned on, and the hydraulic cylinder 25 is extended. The state in which the steel pipe A is held by the support is maintained, and at the time of power-off to the motor 6, the opening / closing valve 80 is opened, and the hydraulic cylinder 25 is driven by the return force from the spring 25a. The contraction enables the pinching of the steel pipe A to be released. Incidentally, the control of the hydraulic cylinders 25 and 33 may be performed separately by on / off valves, respectively.

The steel pipe cutting device of the present invention is configured as described above, and the drive mechanism 1 is suspended by a crane, and the connecting shaft 3 is sequentially connected to the rotary shaft 2 by the required length, and the cutter is cut at the lower end of the lower connecting shaft 3a. (4) is attached and the cutter 4 with the hydraulic cylinder 33 contracted is inserted into the steel pipe A to be cut, and the mounting plate 11 of the drive mechanism 1 is placed on the steel pipe A. , As shown in FIG. 1, the blade 32 of the cutter 4 comes to the desired height of cutting of the steel pipe A, and the two-pronged bracket 23 of the chuck mechanism 13 is connected to the steel pipe A as shown in FIG. The upper part is fitted out to the wall. At this time, by adjusting the centering mechanism 12 provided around the cylindrical body 8 to the inner diameter of the steel pipe A to cut | disconnect, the rotating shaft 2 is substantially coaxial with the steel pipe A. It is a batch.

In this state, when the switching valve 78 of the hydraulic supply source 76 is operated to supply hydraulic pressure to the chuck mechanism 13 and the cutting machine 4, the chuck mechanism 13 is a steel pipe by the extension of the hydraulic cylinder 25. (A) is fitted and the drive mechanism 1 is fixed to the steel pipe A. As shown in FIG.

In addition, the cutter 4 retracts the reaction force roller 42 with the extension of the hydraulic cylinder 33, and presses the inner peripheral surface of the steel pipe A, thereby advancing the frame 31 to advance the blade 32 to the steel pipe A. ) Into the inner circumferential surface (see Figs. 5 and 7).

When the motor 6 is started while the hydraulic pressure is supplied in this state, the rotation of the rotary shaft 2 is transmitted to the cutter 4 via the coupling shaft 3, and the cutter 4 rotates the blade ( 32 starts the circumferential surface of the steel pipe A in a pressurized state, the blade 32 is rotated in the same circumferential position, the blade end is dug into the steel pipe A, and the steel pipe A by continuing this state Cut the circumference of the wall.

When the cutting is completed, the motor 6 is stopped, and the supply of hydraulic pressure is also stopped to switch the switching valve 78 to the discharge side.

When the hydraulic pressure is released, the hydraulic cylinder 33 of the cutter 4 contracts by the axial pressure of the accumulator 54, the reaction force roller 42 returns to the forward position, and the blade 32 retreats, The relationship between the blade 32 and the reaction force roller 42 is in the most contracted state.

Further, at the same time as the stop of the motor 6, the on-off valve 80 is opened, the hydraulic cylinder 25 returns to the contracted state by the pressure of the spring 25a, and the chuck mechanism 13 of the steel pipe A When the pinch is released, the driving mechanism 1 is pulled up in this state, and the cutting operation 4 is pulled out of the steel pipe A to complete the cutting operation.

As mentioned above, according to this invention, the wave used for a cutter can improve the sealing property of a hydraulic cylinder, and durability can be improved also when using in waste water.

In addition, the range of steel pipe diameter that can be cut by the blade position and the cutting frame position is wide, and the cutting position can be arbitrarily set by the use of the connecting shaft and the expansion joint of the connecting shaft and the frame. It can correspond to.

In addition, by electrically interlocking the chuck mechanism that fixes the drive mechanism to the steel pipe with the motor, the drive mechanism can be reliably fixed to the steel pipe during cutting, thereby improving the safety of the work.

Claims (9)

It consists of a drive mechanism installed on the upper end of the steel pipe to be cut, and a cutter that is connected to the rotary shaft of the drive mechanism via a connecting shaft to rotate in the steel pipe, the cutter is rotatably attached to the front end of the frame, In the steel pipe cutting device, which is formed so that the blade is pushed to the steel pipe for cutting by pressing the reaction roller installed through the link mechanism on the rear end of the frame to the inner circumferential surface of the steel pipe by pressing the cylinder on the frame. A hydraulic cylinder is used as the cylinder of the cutter, and the hydraulic supply pipe is connected to one of the two rooms in the cylinder body partitioned with a piston to extend the hydraulic cylinder, while the hydraulic pipe is connected to the other room to deflate the hydraulic cylinder. Steel pipe cutting device characterized in that the accumulator is connected through. The steel pipe cutting device according to claim 1, wherein the cutter freely supports the blade with the support block, and the support block is replaceably attached to the receiving unit installed at the front end of the frame. The mounting plate is provided on the upper part of the frame of the cutter, and the square plate fixed to the lower end of the attachment shaft of the connecting shaft is moved on the attachment plate along the guides provided on both sides of the attachment plate in the front-rear direction. The frame and the connecting shaft of the cutter where the mounting plate and the square plate come into contact with each other by fastening the plurality of adjustment holes provided in the front and rear directions of the mounting plate and the bolt holes of the square plate with bolts. Steel pipe cutting device characterized in that the connection position is variable in the horizontal direction. The steel pipe cutting device according to claim 1 or 2, wherein the connection between the frame of the cutter and the connecting shaft is adjustable up and down by an elastic joint. 3. The driving mechanism according to claim 1 or 2, wherein the drive mechanism has an insertion portion into the steel pipe at the lower portion of the casing, and interlocks a motor installed on the casing with a rotating shaft provided in the insertion portion, so that the outer side of the insertion portion is provided with a steel pipe. It is formed by installing a chuck mechanism that firmly supports the circumferential wall with a cylinder, and connects the cylinder of the chuck mechanism and the cylinder of the cutter with a common hydraulic supply source, and opens and closes the check valve in the middle of the hydraulic supply passage connected to the cylinder of the chuck mechanism. A steel pipe cutting device, characterized in that the valves are installed in parallel, and the motor and the on / off valve are electrically connected to each other so that the chuck mechanism can contract the cylinder by turning on and off the motor. 4. The steel pipe cutting device according to claim 3, wherein the connection between the frame of the cutter and the connecting shaft can be adjusted up and down by an elastic joint. 4. The driving mechanism according to claim 3, wherein the drive mechanism includes an insertion portion into the steel pipe at the lower portion of the casing, and interlocks a rotation shaft installed in the insertion portion with a motor provided on the casing, thereby forming a circumferential wall of the steel pipe outside the insertion portion. And a check valve and a shut-off valve in parallel in the middle of the hydraulic supply passage connecting the cylinder of the chuck mechanism and the cylinder of the cutter to a common hydraulic supply source. And the motor and the on-off valve are electrically connected to each other so that the chuck mechanism is capable of contracting the cylinder when the motor is turned off and on. 5. The driving mechanism according to claim 4, wherein the drive mechanism includes an insertion portion into the steel pipe at the lower portion of the casing, and interlocks a rotary shaft installed in the insertion portion with a motor provided on the casing, and the circumferential wall of the steel pipe is formed outside the insertion portion. And a check valve and a shut-off valve in parallel in the middle of the hydraulic supply passage connecting the cylinder of the chuck mechanism and the cylinder of the cutter to a common hydraulic supply source. And the motor and the on-off valve are electrically connected to each other so that the chuck mechanism is capable of contracting the cylinder when the motor is turned off and on. 7. The driving mechanism according to claim 6, wherein the drive mechanism includes an insertion portion into the steel pipe at the lower portion of the casing, and interlocks a rotation shaft installed in the insertion portion with a motor provided on the casing, and the circumferential wall of the steel pipe is formed outside the insertion portion. And a check valve and a shut-off valve in parallel in the middle of the hydraulic supply passage connecting the cylinder of the chuck mechanism and the cylinder of the cutter to a common hydraulic supply source. And the motor and the on-off valve are electrically connected to each other so that the chuck mechanism is capable of contracting the cylinder when the motor is turned off and on.