JPS637213A - Under-water cutting machine for tube - Google Patents

Abstract

PURPOSE:To avoid direct collision between a cutter edge and a tool rest, and reduce the wear of the cutter edge by forming a slope on the tool rest of a cutting machine, expanding from the contact position of a punching cutter edge with the rest toward the side of the punching cutter, and forming the rest to have an approximate V-section. CONSTITUTION:A slope 29 is formed, expanding from the contact position 28 where the tip 27 of a punching cutter 12 has a line contact with a tool rest 14, toward the side of the punching cutter 12. The section of the rest 14 is approximately 'V' shaped. In cutting a neutron measurement tube 16 under water, the punching cutter 12 is pressed via remote control. A force pressing the punching cutter 12 is as well dispersed to the slope 29 from the side of the cutter 12 via the tube 16. Therefore, the rest 14 is protected from direct biting by the tip 27 of the punching cutter 12 and the wear of the cutter edge an be reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an underwater cutting machine for cutting pipe bodies disposed in a nuclear reactor in water such as coolant, and particularly relates to an underwater cutting machine for cutting pipe bodies arranged in a nuclear reactor in water such as coolant. This invention relates to an underwater cutting machine for tubular bodies, which causes less damage to the pusher blade that cuts the material and requires less frequent replacement of the pusher blade.

(Conventional technology) Inside the reactor, a local power range monitoring system (
A large number of tube bodies are installed, including neutron measurement tubes (LPPM) and dry tubes.

After these tubes have been used for a predetermined period of time or when they break down, they are removed from the furnace during periodic inspection and replaced with new tubes. Since these tubes are contaminated with high concentrations of radiation, their replacement must be carried out using special tools while taking precautions against radiation.

That is, the replacement work is carried out deep underwater to shield radiation, and the specialized tools used are remotely controlled by electricity, water pressure, etc. to reduce the amount of radiation exposure to workers as much as possible.

The old pipes taken out of the furnace are temporarily stored in a fuel pool, but at this time, long pipes are cut into short lengths for transportation and storage reasons before being stored.

At this time, the underwater cutting scale used is generally constructed as shown in FIGS. 4 and 5. That is, the cutting-like main body 1 and the grip main body 2 for fixing the tube body are integrally assembled by the bracket 3 and the two side plates 4,
Furthermore, it is suspended from the hanging plate 8 via the terminal fitting 5°6 and the wire row 77. The suspension plate 1 is connected to an overhead crane (not shown) via a wire lobe 9. The underwater cutting machine is set in a predetermined position by operating a lifting machine.

The inlet main body 1 is provided with a piston 10.11 which is driven by water pressure inside the cylinder.
A push blade 12 is removably attached to the tip of the holder with a mounting bolt 13. On the other hand, a blade holder 14 for receiving the cutting edge of the pusher blade 12 is similarly detachably attached to a position opposite to the pusher blade 12 using a mounting bolt 15.

The tube bodies such as the neutron measurement tube 16 are connected to the push blade 12 and the blade holder 14.
The head 17 and the receiver of the grip main body 2 are gripped and fixed by the seat 18.

The head 17 is driven in the axial direction by the repulsive action of a resilient spring 19 installed on the shaft and by high-pressure water supplied to a cylinder provided in the grip body 2 via a hydraulic hose 20 and a joint 21. It uses piston action.

The neutron measurement tube 16, which is a tube inserted between the push blade 12 and the blade holder 14, is first energized by high-pressure water supplied to the cylinder of the cutting machine body 1 via the water pressure hose 22 and the joint 23. The push blade 12 and blade holder 14 are driven by the piston.
It is crushed into a flat shape. After that, high pressure water is further supplied to the pistons 1o and 11, and the sixth
As shown in the enlarged view of the cut portion, the compressed tubular portion is cut along the center line by the strong pressure of the pusher blade 12. Here, since the opposing tube walls of the tube body come into close contact with each other in a flat state at the stage of being crushed, the tube end after cutting is tightly closed. Therefore, after cutting, the substance inside the tube is sealed, and the substance containing radioactivity is prevented from scattering outside the tube.

The cut tube separates at the cutting edge of the pushing blade 12, and thereafter, as long as the piston continues to be driven, the cutting edge of the pushing blade 12 is pressed against the blade holder and directly bites into it.

That is, as shown in the state at the moment of cutting in FIG. 6, the cut neutron measuring tube 16.16 receives a force that pushes open the cut portion by the cutting edge of the pushing blade 12. FIG. 7 is a diagram illustrating the working relationship of the forces. A point A1 where the pushing blade 12 that cuts the tube body with the pressing force P contacts the tube body on its side surface
When the cutting edge angle of the pushing blade 10 is 2θ and the force acting perpendicularly to the side surface of the pushing blade 12 is N, the component force in the vertical direction of N is represented by f, and the relationship P=2f holds true. The horizontal component force in the - direction N is represented by F, and this force F acts to push open the cut tube. A frictional resistance force between the back surface of the flattened tube and the blade receiving surface 24 of the blade holder 14 can be considered as a drag force against this F, but since the conventional blade receiving surface 24 was flat, this frictional resistance force is smaller than the push-open force F, the tube bodies cannot be kept in the cutting position, and the cutting edge of the push blade 12 advances through the gap that has been pushed open, and the blade holder 1
There were many cases where the blade bit into the blade violently and caused damage to the cutting edge.

Conventionally, in order to prevent the cutting edge of the pushing blade from biting into the blade holder and being damaged immediately after cutting, high-pressure water supplied to a piston that applies pressing force to the pushing blade 12 has been controlled.

In this control method, immediately after the push blade 12 cuts the pipe body, the operator of the high-pressure water pump confirms that the pressure gauge pointer of the high-pressure water pump swings back, and immediately opens the bypass valve to drain the high-pressure water system. was discharged into an open tank (not shown) to release the suppressing action of the piston and stop the biting caused by the forward movement of the pusher blade.

However, from the moment the tubular body is cut, the tubular body separates on both sides from the cutting line. Therefore, from now on, the entire suppressing force of the piston acts on the cutting edge of the pushing blade, and this cutting edge bites directly into the blade holder.

If the setting work is continued in this way, the push blade 12 and the blade holder 14 will gradually become damaged and the cutting efficiency will decrease.

For example, after a long period of use, the pushing blade 12 has many worn parts 25 on its cutting edge, as shown in FIG. In the figure, 4
This shows an example where wear and tear occurred in several locations. Similarly, a large number of scratches 26 are generated on the blade holder 14 as shown in FIG. 9. If use continues in this state, the cutting edge of the pushing blade 12 will dig deeper into the scar 26 of the blade holder 14, so that the wear and tear on both parts will progress gradually and additively.

Therefore, the sharpness of the push blade 12 deteriorates, and the efficiency of cutting the tube body gradually decreases. Therefore, the push blade and the blade holder are replaced after a specified number of cutting operations have been performed, or at a stage when the efficiency of the operation begins to be affected. To perform this replacement work, lift the entire suspended underwater cutting machine out of the water by operating a lifting machine, check the state of wear and tear, and if the degree of wear and tear is more severe than specified, remove the mounting bolts 13 and 15 and replace the push blade with a new one. After replacing the cutting machine with the blade holder and the blade holder, the cutting machine was returned to the water and the cutting operation continued.

(Problems to be Solved by the Invention) As described above, in conventional underwater cutting machines, since the blade receiving surface of the blade holder was flat, the cut pipe body was easily opened from the cutting part by the pushing blade, and the pipe body was easily opened from the cutting part by the pushing blade. Immediately after cutting the body, the cutting edge of the pushing blade directly collides with the blade holder and bites into it, which often causes the cutting edge to become worn or damaged. Therefore, the sharpness of the pusher blade deteriorates after a short cutting operation, necessitating frequent replacement of the pusher blade and the blade holder.

As the sharpness of the cutting edge decreases, the pressing force required to cut the tube increases, and the cutting process becomes proportionally more time-consuming. Additionally, as the pressing force increases, the impact received by the cutting edge also increases, accelerating wear and tear. The fact that the push blade has a short lifespan and is frequently replaced leads to a decrease in the efficiency of cutting the tube body.

In addition, since replacing push blades and the like increases radiation exposure for workers, there is also a fundamental operational issue in that the number of replacements must be kept as low as possible.

The present invention was devised to solve the above-mentioned problems, and by improving the shape of the blade holder, wear and tear on the push blade and blade holder can be reduced and their lifespan can be extended, making it easier to replace them. It is an object of the present invention to provide an underwater cutting machine for pipe bodies that can reduce the frequency of cutting operations, improve the efficiency of cutting work by the underwater cutting machine, and reduce the amount of radiation exposure of workers as much as possible.

[Structure of the invention]

(Means for Solving the Problems) The underwater cutting machine for pipe bodies according to the present invention includes a push blade attached to the tip of a hydraulic piston that is reciprocated by remote control;
It has a blade holder disposed at a position facing the pushing blade, and by firmly sandwiching the tubular body between the pushing blade and the blade holder, the tubular body is crushed into a flat+I'l shape, and the pushing blade In the underwater cutting machine for cutting pipe bodies, the blade holder is formed with an inclined surface that widens from the contact position of the pushing blade tip toward the pushing blade side, and the cross section of the blade holder is approximately V. The gist is that it was formed to resemble the shape of a letter.

(Function) According to the underwater cutting machine having the above configuration, the blade holder forms an inclined surface that expands toward the pushing blade side starting from the contact position of the tip of the pushing blade, and the cross section of the blade holder is approximately V-shaped. Since the tube body is formed in a shape, even immediately after the tube body is cut, the tube body is held in the position at the time of cutting without unraveling. Further, the force for pressing the pusher blade is also distributed in the slope direction via a tube cut from the side surface of the pusher blade, and is transmitted to the slope of the blade holder. This prevents the cutting edge of the pushing blade from directly colliding with the blade holder and biting it in, and furthermore, the axial pressing force of the piston that was concentrated on the pushing blade is dispersed as a pressing force on the inclined surface of the blade holder. As a result, the pressing force acting directly on the cutting edge of the pushing blade can be reduced, reducing wear and tear on the cutting edge, reducing the frequency of replacing the pushing blade, and greatly improving cutting efficiency.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings.

Note that the underwater cutting machine for tubular bodies according to the present invention is characterized by the shape of its blade cradle, and other components are the same as those of the conventional example, so a description of the common parts will be omitted.

FIG. 1 shows an enlarged view of the blade holder 14 used in the underwater cutting machine for tubular bodies according to the present invention.
An inclined surface 29 is provided that expands toward the pushing blade side from a position 28 where the blades 7 abut in line contact, and the cross section of the blade holder 14 is approximately V-shaped.

A situation in which the neutron measuring tube 16 is cut by an underwater cutting machine incorporating the blade holder 14 having the inclined surface 29 will be described with reference to FIGS. 2 and 3. Since the blade holder 14 has sloped surfaces 29 on both sides from the abutting part of the cutting line 30 of the tube body, when the neutron measurement tube 16 is cut, the flattened portion is formed on the sloped surface. As a result of being bent along the line 29, even if tension is applied in the axial direction of the tube, the portion at the cutting line is unlikely to be separated.

On the other hand, lines for pressing the edges of the respective tubes are formed on both sides of the pushing blade as shown in FIG. A force that strongly presses the edge of the tube against the inclined surface 29 of the blade holder 14 acts along this pressing line 31 .

This force corresponds to the force N acting perpendicularly on the side surface of the pushing blade at point A explained in FIG. The force acting on this inclined surface is larger than half of the pressing force acting perpendicularly on the conventional pushing blade, so the frictional resistance between the edge of the tube and the inclined surface is also lower than the flat blade receiving surface of the conventional example. significantly increased compared to the previous case. Therefore, the force acting on the inclined surface serves to press and fix the edge of the cut tube by the side surface of the push blade against each inclined surface immediately after cutting the tube, and the force acting on the inclined surface serves to press and fix the edge of the cut tube to each inclined surface by the side surface of the push blade. This prevents both tube bodies from disassociating.

Therefore, compared to a conventional blade holder having a flat blade receiving surface, the pushing blade is prevented from advancing immediately after cutting, and the blade edge is less likely to dig into the blade holder immediately and be damaged.

In addition, the total pressing force acting on the pushing blade is divided into the pressing force from the side of the pushing blade to the inclined surface and the pressing force acting on the cutting edge, so the pressing force on the cutting edge immediately after cutting is reduced compared to conventional methods. This reduces the size of the blade and proportionally prevents the cutting edge from digging into the blade holder.

Note that this embodiment uses an underwater cutting machine that cuts circular pipes etc. underwater using a push blade and a blade holder, but the basic idea of the present invention is to use a push blade and a blade holder. It goes without saying that a press-type cutting machine that uses a table to cut rod-shaped objects or tubular objects can be widely applied in general.

〔Effect of the invention〕

As explained above, in the underwater cutting machine for tubular bodies according to the present invention, the blade holder is provided with an inclined surface that expands from the contact position of the pushing blade tip toward the pushing blade side, and the blade holder is Since the cross section is formed to be substantially V-shaped, each tube body is fixed in the position at the time of cutting even immediately after the tube body is cut.

Further, the force for pressing the pusher blade is also distributed to the inclined surface from the side surface of the pusher blade via the tube body. Therefore, the cutting edge of the pushing blade is prevented from directly biting into the blade holder, and furthermore, the pressing force of the piston concentrated on the pushing blade can be reduced, so that wear and tear on the cutting edge can be prevented. Therefore, the frequency of replacing the push blade can be reduced, and cutting work efficiency can be greatly improved.

Furthermore, since the replacement work and maintenance work for push blades, etc., can be reduced, the radiation exposure of workers (1 mfA) can be significantly reduced, which is an excellent effect.

[Brief explanation of drawings]

Fig. 1 is an enlarged perspective view showing only the blade holder used in the underwater cutting machine for pipe bodies according to the present invention, and Fig. 2 shows a state in which the blade holder of Fig. 1 is used to cut a pipe body. 3 is a plan view of the pipe body and blade holder in FIG. 2, FIG. 4 is a front view showing the configuration of a conventional underwater cutting machine, and FIG. 5 is a cut frozen wood body in FIG. 4. FIG. 6 is a cross-sectional view showing the state in which a pipe body is cut by conventional underwater cutting, FIG. 7 is an explanatory diagram showing the force relationship acting on the blade surface of the push blade, and FIGS. 8 and 9. These are perspective views showing the push blade and the blade holder after long-term use. DESCRIPTION OF SYMBOLS 1... Main body for cutting, 2... Grip body, 3... Bracket, 4... Side plate, 5.6... Terminal fitting, 7,
9... Wise rope, 8... Hanging board, 10.11.
... Piston, 12 ... Push blade, 13.15 ... Mounting bolt, 14 ... Blade holder, 16 ... Neutron measurement tube, 17 ... Head, 18 ... Receiver is seat, 19... Repulsion spring, 20.22... Water pressure hose, 21.23...
・Joint, 24... Blade receiving surface, 25... Worn part, 26.
... Scar, 27 ... Tip of push blade, 28 ... Contact position, 29 ... Inclined surface, 30 ... Cutting line, 31 ...
Suppression wire, 32.33...Mounting bolt hole. Applicant's agent Hisada Hatano Figure $3 Figure No. 4 Engraving 9 Figure $6 Figure No. 7 Figure θ

Claims (1)

[Claims] It has a push blade attached to the tip of a hydraulic piston that is reciprocated by remote control, and a blade holder placed in a position facing the push blade, and the tube body is firmly placed between the push blade and the blade holder. In an underwater cutting machine for tubular bodies that crushes the tubular body into a flat shape by pinching and then cuts the tubular body with a pushing blade, the blade holder has a slope that expands from the contact position of the tip of the pushing blade toward the pushing blade side. An underwater cutting machine for a pipe body, characterized in that the cross section of the blade holder is formed into a substantially V-shape.