JPS62255018A - Underwater electric discharge cutter - Google Patents

Abstract

PURPOSE:To make it possible to aim at facilitating and ensuring a cutting process with the use of an underwater electric discharge cutter for cutting a neutron measuring pipe which is stuck in a boiling water type nuclear reactor, and so forth, by surely gripping and securing the pipe on both longitudinal sides of a part to be cut with the use of grippers. CONSTITUTION:An underwater electric discharge cutter 1 has a columnar support section 3 adapted to the hooked on an upper grid plate 2 in a nuclear reactor vessel. Further, an electrode blade 14 for electric discharge cutting is in a log and thin plate shape, and is arranged horizontally in the space 7 between an upper casing 6a and a lower casing 6b, and is rotated about one end, as a center, by a predetermined angle in a horizontal plane. Further, the upper and lower casings 6a, 6b are provided, respectively with upper and lower grippers 22, 23 for securing and holding a neutron measuring pipe 20 at positions above and below a part to be cut. Further, when the neutron measuring pipe is cut under electrical discharge by the electrode blade 14, no cutting blade stagnates during cutting in this underwater cutter, thereby it is possible to smoothly progress the process.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an underwater discharge cutting machine used for cutting stuck neutron measurement tubes in boiling water nuclear reactors, etc. This article relates to an underwater discharge cutting machine that facilitates and ensures reliable operation.

(Prior Art) It is known that in boiling water reactors and the like, neutron measurement tubes are removed during periodic inspections and replaced with new tubes. The neutron measuring tube is arranged perpendicularly to the core of the reactor pressure vessel, its lower end is inserted into the housing at the bottom of the reactor pressure vessel, and its upper end is supported by the upper grid plate. A spindle is attached to the upper end of the neutron measuring tube so that it can be expanded and retracted by being urged upward by a spring, and the upper end of this spindle is fitted into four parts of the lower surface of the upper grid plate from below.

Therefore, when taking out the neutron measurement tube, the neutron measurement tube is gripped with a grip suspended from above the reactor through the lattice gap of the upper grid plate, and the spindle is gripped and pushed down with another grip. After removing the upper end of the spindle from the recess on the lower surface of the upper grid plate, the neutron measurement tube is lifted above the upper grid plate. Note that the lifted neutron measurement tube is moved to a predetermined position using a moving grip, for example, in an inclined state so as not to be exposed above the water surface.

By the way, the spindle at the top of the neutron measurement tube is approximately 600 mm.
It is a round bar with a length of #. The lower end of this round bar is housed in the neutron measurement tube, and by pushing down the spindle against a spring that urges it upward, it can be removed from the recess in the lower surface of the upper grid plate. However, after long-term operation of a nuclear reactor, the spindle may not be pushed down due to neutron irradiation or other causes, resulting in a so-called stuck state. In such a stuck state, the spindle cannot be pushed down and therefore cannot be removed from the upper grid plate.

When the neutron measurement tube is stuck and cannot be removed, the upper part of the neutron measurement tube is cut off using an underwater cutter suspended from above the reactor, and the upper cut piece (hereinafter referred to as the upper part) is removed. After pumping it out downward using a predetermined gripping tool, it is pulled upward, and at the same time, the cut piece at the bottom (hereinafter referred to as "lower piece") is handled upward using another gripping tool. As a cutting machine for such a neutron measurement tube, there is a pressure cutting machine, a discharge cutting machine 81, or the like. The pressurized cutting machine I uses water pressure to cut pipes, and is used, for example, to cut K11I pipes of thick-walled local power detectors (LPRMs). Furthermore, discharge cutting is used to cut thick tubes such as dry tubes.

When using a pressurized cutter, the neutron measurement tube is pushed through, so bending of the neutron measurement tube does not pose much of a problem. However, in the case of an electric discharge cutting machine, the electric discharge cutting blade is exposed to a constant discharge l! IFF
Since cutting is performed gradually while holding A, if the neutron measurement tube is bent at the cutting part, the cutting path may be blocked, causing a second-long inconvenience. .

For example, the electrode blade comes into contact with the cut end of the neutron measurement tube, and arc generation stops. In this case, pull back the electrode blade and
After that, it is necessary to move the tool forward again and start cutting twice. In addition, the electrode blade is caught in the closed cut,
There is also the inconvenience that the electrode blade is fixed. In such a case, extra effort is required, such as moving the gripping tool that grips the neutron measurement tube I tube and opening the cut.

Conventionally, when cutting a neutron measurement tube with such an electric discharge cutting machine, the upper and lower predetermined positions of the cut part of the neutron measurement tube are held at the upper and lower positions by an upper and lower piece grip, respectively, which are provided separately from the electric discharge cutting machine. Measures are taken to securely hold the cut portion so that it does not curve.

(Problem to be solved by the invention) When the upper part of a neutron meter tube is gripped with a grip different from the cutting machine, the weight of the grip is applied to the neutron measurement tube, pushing the upper piece downward. This tends to cause the cut end to become obstructed. Therefore, it is necessary to delicately control the auxiliary lobe that hangs the gripping tool, and controlling the hanging position with high precision requires extremely troublesome handling.

For this reason, work efficiency tends to be extremely poor.

Additionally, if the fitting tool that grips the lower part of the cut section of the neutron measurement tube is configured separately from the cutting machine, its own weight tends to cause the lower piece of the neutron measurement tube to curve. However, the incision is likely to become occluded. Therefore, it becomes very troublesome to handle the auxiliary lobes that suspend the gripping tool.

Note that the configuration of conventional gripping tools was such that the holding force of the gripping tool was controlled by the operation of auxiliary lobes suspended from above the reactor, so the handling of the auxiliary lobes made it difficult to grip the neutron measurement tube. There was also the possibility that problems such as lack of certainty would arise.

The present invention has been made in view of the above circumstances, and is capable of reliably gripping and fixing a rod-shaped object to be cut, such as an underwater pipe, on both longitudinal sides of the cutting part, thereby eliminating the inconvenience caused by the curvature of the object to be cut. It is an object of the present invention to provide an underwater discharge cutting machine 11i that can easily and reliably remove the water and perform smooth underwater discharge cutting.

(Structure of the Invention) (Means for Solving the Problems) The present invention provides a movable electrode blade on a support member for insertion into water, and discharge-cuts a rod-shaped object placed in water using the electrode blade. In the underwater discharge cutting machine, a pair of gripping tools are provided on the supporting member to fix and hold the object to be cut on both sides of the cutting section in the longitudinal direction, and each of the gripping tools is controlled by water pressure JL in a direction toward and away from the object to be cut. ! It is characterized by having a moving part that moves forward and backward by a force, and a gripping part that is movable integrally with the moving part and opens and closes in the radial direction of the object to be cut by hydraulic drive.

(Function) Since a pair of gripping tools for fixing and holding both sides of the cut portion of the object to be cut are provided on the supporting member provided with the cutting portion for electric discharge, the arrangement relationship between the cutting portion and the gripping tools is always constant. Therefore, during discharge cutting by the cutting section, the fixing and holding position of the object to be cut does not change, and the weight of the gripping tool does not independently apply to the object to be cut. Therefore, the object to be cut is not curved and the cut end is not unnecessarily closed.

Further, since the movement of the gripping tool and the gripping force are controlled by water pressure, the 01 operation is reliable, and the necessary gripping force can be sufficiently obtained. Therefore, the reliability of fixing and holding the object to be cut by the gripping tool is increased.

Furthermore, since the gripping force is driven by hydraulic pressure, control of the gripping force and the like can be performed reliably with high precision and is easy. Therefore, with a relatively easy operation, it is possible to reliably prevent sticking or pinching of the cut portion due to blockage of the cut end, and underwater discharge cutting can be performed smoothly.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that this embodiment concerns an underwater discharge cutting machine used for cutting a neutron meter i11 tube of a boiling water nuclear reactor.

FIG. 1 shows a partially sectional side view of the underwater discharge cutting machine placed at a cutting position, FIG. 2 shows its plan view, and FIG. 3 shows its bottom view.

Underwater discharge cutting 811 is performed on the upper grid plate 2 in the reactor pressure vessel.
It has a columnar support member 3 for hanging on to. This support member 3 has a rectangular parallelepiped support block 5 provided with seven flange 4 at its upper end, and a columnar case 6 connected to the lower end of this support block 5. As shown in FIG. 2, the flange 4 has a substantially rectangular plate shape, and is attached with its corner portion twisted approximately 90 degrees on a plane with respect to the corner portion of the support block 5. Further, the columnar case 6 has a rectangular cylindrical shape, and the support block 5
It is fitted into the body and fixed by welding, etc. This columnar case 6 has an air space 7 near its lower end and is divided into two vertically.The upper part (upper case) 6a and the lower part (lower case) 6b are connected to each other by a connecting piece 8. It is connected. The connecting piece 8 has a bent plate structure with wide openings on the sides in order to avoid interference with electrode blades, which will be described later. Further, 6C is a reinforcing wire provided at the lower end of the lower case 6b, which covers and protects the lower grip tool to be described later.

A lifting eye 10 is provided upright on the flange 4 at the upper end of the support member 3 via a cross plate-shaped mounting seat 9. This lifting eye 10 is connected to a hanging tool (not shown) and is used for lifting and lowering from above the reactor. Also,
A pair of downward forks 11 are provided on two adjacent side surfaces of the support block 5. This fork 11 is removably hooked onto two adjacent sides of the upper grid plate 2 from above, and is used for positioning the support member 3. A hanging ring 12 is attached to the upper end of each fork 11, and by connecting an auxiliary rope or the like (not shown) to the hanging ring 12, adjustment of the position of the fork 11 on the upper lattice plate 2 is performed. .

A pair of auxiliary latching arms 13 are provided to protrude in a direction opposite to the direction in which the fork 11 of the support block 5 protrudes. As shown in FIG.
It is placed on the fork 11 opposite to the latching position, and stabilizes the latching state of the electric discharge cutting machine 1 to the cutting position.

The electrode blade 14 for discharge cutting is long and plate-shaped, and is installed horizontally in 7 parts of the space between the upper case 6a and the lower case 6b.
As shown by the imaginary 11Aa in FIG. 2, it is arranged to rotate by a predetermined angle on a horizontal plane about one end. That is, as shown in FIG. 1, a rotary drive mechanism 15 consisting of a servo motor, a speed reducer, etc. is provided at the inner bottom of the upper case 6a and is sealed watertight by a metal case 15a.

The output shaft 16 of this rotary drive mechanism 15 is vertically protruded from the lower end of the upper case 6a, and the electrode blade 1 is attached to the output shaft 16.
One end of 4 is connected. The rotation drive mechanism 15 is connected to an underwater cable 17 suspended from a power supply device (not shown) provided above the reactor. This underwater cable 17 is a multicore cable, and includes wiring for controlling the rotation of the servo motor, wiring for supplying discharge current, and the like. The discharge current is metal case 1
It is supplied to the electrode blade 14 via 5a. The servo motor is connected to a capacitor box 18 attached to the upper case 6a via a communication cable 19, thereby achieving load homogenization. The electrode blade 14 is set to reciprocate by a certain angle (for example, 270 degrees) along a locus shown by the imaginary line a in FIG. This is to cut the installed neutron measurement tube 20.

Note that the lower end of the upper case 6a is provided with the
As shown in the figure, a pair of holders 21 are provided in which the electrode blade 14 is housed in the maximum rotated position. Each holder 2
Reference numeral 1 denotes a frame-shaped member that covers the upper and lower sides and the rotating end side of the electrode blade 14, and prevents the electrode blade 14 from being damaged due to contact with parts inside the furnace during movement such as raising and lowering the entire discharge cutting surface.

In this case, upper case 6a and lower case 6b are provided with an upper grip 22 and a lower grip 23, respectively, for fixing and holding the neutron measurement tube 20 at the upper J3 and lower parts of the cutting section, respectively. Each gripping tool 22.23 is provided with a moving part 24.25 provided in each case 6a, 6b and moving toward and away from the neutron measurement tube I pipe 20 by hydraulic drive, and each moving part 24.
．． 25 and grip portions 26 and 27, which are movably attached to the grip portion 25 and opened and closed by hydraulic drive, respectively. These moving parts 24.25 and gripping parts 26.27 are operated by hydraulic cylinders 28.29°30.31 as hydraulic driving means.
Pressurized water is supplied to these from a pump device (not shown) located above the reactor. 32, 33, and 34 are pressurized water supply pipes from above, and 35 is a water box having a compartment connected to these pipes. The water box 35 is supported by the upper case 6a via a bracket 6d, and flexible tubes 36, 37, 38 are connected to each chamber of the water box 35 to each of the upper and lower hydraulic cylinders 28, 29, 30, .
It branches out into 31 branches.

In addition, since the upper gripper 22 and the lower gripper 23 have substantially the same configuration, the upper gripper 22 will be described below as a representative, and the description of the configuration of the lower gripper 23 will be omitted.

FIG. 4 shows an enlarged view of the upper gripper 22 shown in FIG.
FIG. 5 shows a partial cross-section of the side structure in the direction of arrow V in FIG. 4, and FIG. 6 shows a partial cross-section of the bottom structure in the direction of arrow V in FIG.

As shown in FIGS. 4 and 5, the moving part 24 has a structure in which a moving hydraulic cylinder (hereinafter referred to as moving cylinder) 28 is slidably supported on a base plate 39 provided horizontally within the upper case 6a. It has become. That is, the base plate 39
has a rectangular shape, and as shown in FIG. 4, side plates 40 hang downward from both sides in the transverse direction, forming a substantially U-shaped side surface. On the other hand, the moving cylinder 28 has a square columnar shape, is slidably fitted to the lower surface of the base plate 39 and the inside of the side plate 40, and is supported by a guide rail 40a.

Further, stopper plates 4 are provided at both ends of the base plate 39 in the longitudinal direction.
1 is suspended by a bolt 42. Both ends of a horizontal piston shaft 43 are fixed to each stopper plate 41, and a piston 44 provided at an intermediate portion of the piston shaft 43 is in sliding contact with the inside of the moving cylinder 28 via a seal ring 45. Note that the end plates 46 that close both ends of the moving cylinder 28 are screwed onto the cylinder wall, for example, and seal rings 47 are provided at the sliding contact portions with the piston shaft 43, respectively. Further, each end plate 46 is provided with a water passage hole 48, respectively. Each water hole 48 has a water supply and drainage pipe 49.
50 is movably connected to the moving cylinder 28. Each of these water supply and drainage pipes 49 and 50 is a flexible tube 36.
．． 37, and are connected to a pump device above the reactor via a water box 35 and pressurized water supply distribution FF32, 33.

Note that one of the water supply and drainage pipes 49 has a plurality of straight pipes 49a, 4
9b, 49c, and 49d are pipe fittings 49e.

49f and 49G, and piping is arranged around the lower part of the moving cylinder 28 from the outside of the upper case 6a. The other water supply pipe 50 is bent into a single shape and is directly connected to the moving cylinder 28 from the outside of the upper case 6a.

When pressurized water is supplied from one water supply and drainage pipe 49 into one cylinder chamber (m-section cylinder chamber) 28b, the moving cylinder 28 is connected to the neutron measurement tube 20 because the piston 44 is fixed. It is designed to slide in the direction of approach (in the direction of the arrow in Fig. 5). In this case, the water in the other cylinder chamber (rear cylinder chamber>28a) is discharged from the other water supply and drainage pipe 50. Conversely, when pressurized water is supplied from the other water supply and drainage pipe 50 to the rear cylinder chamber 28a, , the moving cylinder 28 is a neutron needle 'I
It slides in the direction away from the II tube 20 (in the direction of arrow C in FIG. 5). In this case, water in the front cylinder chamber 28b is discharged from one water supply and drainage pipe 49.

In this way, the grip part 26 is attached to the moving cylinder 28, which acts on the neutron measuring tube 20 by water supply and drainage.
is provided. As shown in FIGS. 5 and 6, the gripping portion 26 includes the aforementioned hydraulic cylinder (hereinafter referred to as a gripping cylinder) 29 that moves together with the moving cylinder 28, and a gripping arm that is opened and closed by the gripping cylinder 29. 51
and has. The gripping cylinder 29 is the moving cylinder 28
The above-mentioned flexible tube 38 is connected to this gripping cylinder 29 via a water supply and drainage pipe 52. Cylinder 9a inside the gripping cylinder 29
A piston 53 is housed inside with a seal ring 54 interposed therebetween. This piston 53 is urged by a compression coil spring 55 in a direction opposite to the hydraulic load direction (direction of arrow d) (direction of arrow e). Note that a communication hole 29 with the inside of the furnace is provided in the peripheral wall of the spring chamber 29b in which the spring 55 is arranged.
c.

The arm 5 is attached to the piston shaft 56 connected to the piston 53.
A pair of racks 58 are connected by bolts 59 via 7, and a pinion 60 meshes with the racks 58. The binion 60 is integral with the gripping arm 51, and is rotatably attached to the moving cylinder 28 via a bearing 61 and a pin 62, as shown in FIG. Note that the teeth of the pinion 60 are in the shape of a missing circle, and the gripping arm 51 is connected to the non-toothed portion by welding or the like.

The pair of gripping arms 51 are parallel to each other and each rotates about a pin 62 as the pinion 60 rotates. Each pinion 60 is rotationally driven by engagement with the rack 58. Each rack 58 is connected to the piston 53 in the cylinder chamber 29a.
The gripping arms 51 are pushed in the direction of the arrow d in FIG. 6 by the action of the water pressure inside, and each gripping arm 51 rotates in the direction in which the tips of the gripping arms 51 mutually rotate in the direction r'j1M through each pinion 60, that is, in the gripping direction. . Further, when the water pressure in the cylinder chamber 29a is reduced to, for example, about 1 atmosphere, the piston 53 is pushed by the action of the compression coil spring 55, the rack retreats in the direction of arrow e, and the gripping arms 51 are mutually moved. It rotates in the direction in which the tip opens, or in the direction in which the grip is released.

Next, the action will be explained.

First, check to see if the neutron measurement tube is stuck. This action can be performed depending on whether or not the spindle at the upper end of the neutron measuring tube is pressed down with a conventionally known gripping stem for taking out the neutron measuring tube. If a stick neutron measurement tube is found, the underwater discharge cutting machine 1 of this embodiment will be used.

First, as a preparatory operation, the gripping cylinder 2 is placed above the reactor.
A connecting hose 34 for applying water pressure to 9 is connected to a water pressure pump (not shown). In this case, when the pump is stopped, the cylinder chamber 29a of the gripping cylinder 29 is at atmospheric pressure, and the gripping arm 51 is opened by the elastic force of the compression coil spring 55, making it difficult to suspend it through the lattice spacing of the upper lattice plate 2. Therefore, the hydraulic pump is driven to pressurize the cylinder chamber 29a, thereby closing the tip of the gripping arm 51.

Also, the other connection hose 33 is connected to the water pressure pump in the same way,
Water pressure is applied to the rear cylinder chamber 28a of the moving cylinder 28 to move the moving cylinder 28 backward, thereby causing the gripping cylinder 29 to move backward.

In this way, the rear cylinder ff28 of the moving cylinder 28
Holding the water pressure of a, the cylinder W of the gripping cylinder 29
29 The underwater discharge cutting machine is suspended while a is maintained in a pressurized state.

Although not shown, the water pressure pump on the furnace and the connecting hose 3
2.33.34 is connected with a non-rethane quick coupling, and after pressurizing, connect hose 32 from the water pressure pump.
, 33, 34 are kept in the pressurized state even if they are pulled apart.

The lifting is carried out by screwing the terminal fitting of the wire rope of the service platform onto the lifting eye 10 above the furnace, and gradually lowering the wire rope. Then, as shown in FIGS. 1 and 2, the fork 11 is suspended on the upper lattice plate 2.

Next, the bypass valve of the water pressure pump connected to the gripping connection hose 34 is connected to communicate with the water tank on the furnace. As a result, the piston shaft 56 moves forward in the neutron measurement tg20 direction (arrow d direction) by the compression coil springs 55 in the two gripping cylinders, and as shown by the imaginary line in FIG. gripping arm 51
The tip opens. In this case, the spring chamber 29b in the gripping cylinder 29 communicates with the reactor water through the communication hole 29c, so the cylinder'! Water from the reactor water side flows into 29a. After that, connect the transfer connection hose 32 to a water pressure pump, apply water pressure to the front cylinder chamber 28b side of the transfer cylinder 28, open the rear cylinder chamber 28a side, and move the transfer cylinder 28 toward the neutron measurement tube 20. move it forward in the direction of the arrow. Then, the water pressure in the front cylinder chamber 28b is maintained at the position where the moving cylinder 28 is stopped. In this state, the cylinder chamber 29a of the gripping cylinder 29 is pressurized to move the piston 53 forward, and the pinion 60 is moved through the rank 58.
By rotating the gripping arm 51, the gripping arm 51 is closed. In this case, high water pressure is maintained in the gripping cylinder 29 until it firmly grips the neutron measurement tube.

Note that the above is the operation of the upper gripping tool 22, but
Regarding the lower gripping tool 23, the moving cylinder 30 and the gripping cylinder 31 are connected together with the upper gripping tool 22 to the water box 35 via flexible hoses 36, 37, and 38. The above action is carried out simultaneously with 25.

Therefore, the neutron measuring tube 2 holds both gll (upper and lower) of the cut portion by the electrode blade 14 with the upper and lower gripping tools 22.
It is fixedly gripped by 23.

Next, the connector at the upper end (not shown) of the underwater cable 17 is connected to a control device, the voltage and current are controlled to the specified values, and the start button is pressed to drive the servo motor. The servo motor has a fixed stop position feLJt, and a specified rotation angle (for example, approximately 27 mm from one side of the holder 21 to the other).
0') and is stored in the other holder 21. During this process, when the electrode blade 14 approaches the neutron measurement tube 20, discharge cutting starts, and the cutting progresses until the electrode blade 14 passes through the neutron measurement tube 20, and eventually the neutron measurement tube 20 is divided into upper and lower halves. During this time, the lower grips 22 and 23 supported by the same support case 3 firmly fix and hold the cut portion of the neutron measuring tube 20 at the top and bottom, so that the neutron measuring tube 20 is bent, drooped, etc. There is no unnecessary contact or pinching between the electrode blade 14 and the neutron measurement tube 20, and there is no need for retraction. Furthermore, breakage of the electrode and blade 14 is also prevented.

Therefore, the electrode blade 14 can be rotated smoothly, and the neutron measurement tube 20 can be cut reliably and quickly.

After the cutting operation is completed, hold the upper and lower cut pieces of the neutron measurement tube 20 with another lifting grip (not shown), and then remove the gripping tool 2.
2. Operate 23 in the opposite manner to the above.

That is, the gripping cylinder 29.31 is depressurized and the gripping arm 51 is opened by the spring force of the compression coil spring 55.

Thereafter, the rear part of the transfer cylinder 28.30 is pressurized, the front part is released by 1 m, and the cylinder is retracted. Then, another gripping tool (not shown) that grips the spindle portion of the neutron measurement tube 20 is pulled up, and the upper piece (for example, 1 m long) is taken out, carried to a fuel pool, and temporarily stored. Next, the auxiliary hoist is driven to take out the discharge cutter from the upper grid plate 2 and guide it to the next die-cut neutron measurement tube. Then, the cutting machine is set in the same manner as above, and discharge cutting is performed. When all of the molds have been cut, the tools related to the discharge cutting line are collected, cleaned, and stored. Thereafter, the lower part of the neutron measurement tube 20 that remains after being cut is pulled up.

According to such an embodiment, while the neutron meter 31 tube 20 is being cut, the top and bottom of the cut portion can be held fixed, so that the electrode blade 14 can be held fixed.
Work can proceed smoothly without any stagnation or setbacks. especially,
A moving cylinder 28 is used as a means for fixing the neutron measurement tube 20.
．． 30 and gripping cylinders 29, 31, and each cylinder 28, 29, 30, 31 is fixed on the same base consisting of the support case 6 of the electric discharge cutting machine, the neutron measuring tube 20 can be firmly gripped. Moreover, it is stable and maintains the opening of the cut.

In addition, a pair of upper and lower grips 22 and 23 are attached at a predetermined interval to the upper and lower positions of the vertical column-shaped support case 6 sandwiching the electrode blade 14, and each of the grips 22 and 23 captures the neutron measurement tube 20 from one direction. However, since it was made to be tied up, it was performed through a narrow space restricted by the upper lattice plate 2, etc.
(Ideal for cutting the neutron side pipe of 78 rising water reactors, etc.)
It becomes white.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, but can be widely applied to cutting underwater pipes other than neutron measuring pipes in boiling water reactors.

〔Effect of the invention〕

According to the underwater electric discharge cutting machine of the present invention, a rod-shaped object to be cut, such as an underwater vibrator, can be securely gripped and fixed on both sides of the cutting part in the longitudinal direction. It can be removed reliably and smooth underwater discharge cutting can be performed.

[Brief explanation of drawings]

Fig. 1 is an overall view showing one embodiment of the underwater discharge cutting machine according to the present invention, Fig. 2 is a plan view of Fig. 1, Fig. 3 is a bottom view of Fig. 1, and Fig. 4 is a diagram similar to Fig. 1. FIG. 5 is a side view in the direction of the arrow V in FIG. 4, and FIG. 6 is a bottom view in the direction of the arrow ■ in FIG. 1... Underwater discharge cutting machine, 3... Support member, 14...
・Electrode blade, 20... Neutron measurement tube (object to be cut), 22
゜23...Gripper, 24.25...Movement part, 26.
27...Gripping part. Applicant's agent Hatano Iridock 2 Figure sheep 3 Figure 6 Figure

Claims (1)

[Claims] In an underwater discharge cutting machine, a supporting member for insertion into water is movably provided with an electrode blade, and a rod-shaped object to be cut placed in water is discharge-cut by the electrode blade. A pair of gripping tools are provided to fix and hold the tool on both sides in the longitudinal direction, and each of the gripping tools is provided with a moving part that moves forward and backward by hydraulic drive in the direction toward and away from the object to be cut, and a moving part that is movable integrally with this moving part. 1. A submersible discharge cutting machine characterized in that it has a grip section that opens and closes in the radial direction of an object to be cut by hydraulic drive.