JP7407647B2 - Remote cutting method and cutting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a remote cutting method and a cutting device for remotely cutting a steel object to be cut that is located in a location that is not easily accessible to an operator.

When dismantling and removing contaminated steel outer panels of large tanks and condensers, linings of spent fuel pools, etc. at nuclear power plants, they are first cut into easily handleable pieces on site and then transported to another location. This is the procedure for shredding (secondary cutting) into pieces suitable for decontamination treatment and disposal. At this time, when performing primary cutting on an object to be cut that is located at a location that is not easily accessible to a worker, such as a high place or a contaminated location, there is a technique that performs the cutting while being remotely controlled using a traveling body provided with a cutting section.
The apparatus disclosed in Patent Document 1 remotely moves the wall surface of a metal pool, large tank, etc. to a predetermined position using a traveling section and an elevating section, and cuts the wall surface while moving the cutting section.

However, in Patent Document 1, the cutting part (cutter, gas cutter, etc.) is moved along the longitudinal direction of the track rail while moving on a traveling part, which requires work to set the track rail each time, and also requires high The work burden on workers increases in contaminated areas or contaminated areas.
In addition, when workers directly perform the primary cutting of contaminated large tanks at nuclear power plants, they must work at heights on scaffolding, and it is necessary to reduce the worker's exposure to radiation. Regarding the cutting method, the use of fire such as gas cutting may be restricted from the viewpoint of fire prevention.

Japanese Patent Application Publication No. 11-352292

In view of the problems of the prior art described above, an object of the present invention is to provide a remote cutting method and a cutting device that can cut remotely and without flame.

As a first means for solving the above problems, the present invention provides a self-propelled traveling body equipped with a direct-acting cutting section that cuts with an end mill along a linear rail, and a magnet that attracts a steel object to be cut. adsorbing the object to the object to be cut and traveling to a cutting start position;
A cutting step of cutting linearly along the linear rail from the cutting start position with the direct-acting cutting unit while the self-propelled traveling body is stopped, and returning to the cutting start position after cutting;
a moving step of moving with the self-propelled traveling body by the length cut by the direct-acting cutting section;
An object of the present invention is to provide a remote cutting method, characterized in that the cutting step and the moving step are repeated until the object to be cut is cut.
According to the above first means, after the cutting device is installed on the cutting surface to be cut, the cutting work can be carried out by itself, so there is no need to set up a scaffold for the work, and the cutting work can be made remote. Work safety can be improved because the object to be cut can be cut in a straight line without using flames.

As a second means for solving the above problems, the present invention provides a self-propelled type that is equipped with wheels and magnets at the four corners of the chassis and runs while adhering to steel objects to be cut at predetermined intervals using the magnetic force. A running body,
a direct-acting cutting section that is provided with a linear rail and a long hole in which the end mill moves along the advance/retreat direction in the center of the chassis, and that cuts the object to be cut in a straight line along the linear rail;
The cutting resistance generated in a plane parallel to the cutting surface of the end mill of the direct-acting cutting section that cuts while the self-propelled traveling body is stopped is a force F4 in the feed direction of the end mill and a force F5 in a direction perpendicular to the feed. A remote control device characterized in that, when the weight of the self-propelled traveling body is M·g and the static frictional force of the self-propelled traveling body is F3, the end mill is set at a feed rate that satisfies F3>F4+F5+M·g. The purpose of the present invention is to provide a cutting device.
According to the second means, even if the self-propelled traveling body is stuck to the wall surface of the object to be cut, it is possible to cut the object in a straight line while suppressing the cutting resistance caused by the direct-acting cutting section.

According to the present invention, cutting work can be done remotely, scaffolding work is no longer required, and worker safety can be ensured by reducing radiation exposure.
By using an end mill instead of gas cutting as the cutting means, flameless vaporization can be achieved and the risk of fire occurrence can be reduced.

FIG. 3 is an explanatory diagram of the remote disconnection method of the present invention. 1 is a plan view of a remote cutting device of the present invention; FIG. It is a perspective view of a direct-acting cutting part. 3 is an enlarged view of the AA cross section in FIG. 2. FIG. It is an explanatory view of wall surface running of a self-propelled traveling body. FIG. 3 is an explanatory diagram of cutting reaction force while the self-propelled vehicle is stopped.

Embodiments of the remote cutting method and cutting device of the present invention will be described in detail below with reference to the drawings. The remote cutting method and cutting device of the present invention are configured to be applicable, for example, when remotely temporarily cutting off a contaminated large tank or the like in a nuclear power plant.

[Remote disconnection device]
The remote cutting device has a configuration in which a self-propelled traveling body 20 is equipped with a direct-acting cutting section 30, and has a controller (not shown) that allows an operator to remotely control traveling or cutting.
The self-propelled traveling body 20 is magnetically attracted to the outer plate of a large steel tank or the like and travels on four wheels. The four wheels of the self-propelled vehicle 20 are composed of two driving wheels driven by a motor and two driven wheels connected to the driving wheels by a chain or a belt. With this configuration, in addition to ascending or descending on the object to be cut (side surface, slope, etc.), it is also possible to turn 90 degrees on the spot and move laterally.
The direct-acting cutting section 30 employs an end mill system that reciprocates on a linear rail. The linear-acting cutting section 30 includes two linear-acting mechanisms that move the end mill in a direction perpendicular to the cutting surface and in a direction parallel to the cutting surface and parallel to the upward (forward) or downward (backward) direction of the traveling body. ing. Note that electric power, compressed air, hydraulic pressure, or the like can be used as a driving source for the motor of the self-propelled traveling body, the end mill of the direct-acting cutting section, and the direct-acting mechanism.

(Self-propelled traveling body 20)
FIG. 2 is a plan view of the self-propelled vehicle. As shown in the figure, the self-propelled vehicle 20 is made of a non-magnetic metal member (such as aluminum) having a predetermined strength, and includes a chassis 21 that is approximately rectangular in plan view, and has four wheels at the four corners of the chassis 21. It is placed. In each wheel, both ends of a shaft 23 are supported by bearings 24, and the axis of the shaft 23 is arranged parallel to a pair of opposing side surfaces of the chassis 21. The two wheels at the top in the paper of FIG. 2 are front wheels 22a and 22b, the two wheels at the bottom in the paper are rear wheels 22c and 22d, and the motors 25 are attached to the rear wheels 22c and 22d. The motor 25 can use electric power, compressed air, hydraulic pressure, or the like as a driving source. The front wheels 22a, 22b are connected to the rear wheels 22c, 22d, which are driving wheels, by a chain 26 or an endless belt, and become driven wheels. With such wheels, the traveling body moves forward or backward by rotating the two motors 25 in the same direction in the forward or reverse direction. Moreover, if the two motors 25 are rotated in opposite directions, the robot can turn on the spot.
Note that the motor 25 or the wheels have built-in brakes (not shown), and while the brakes are in operation, the wheels are completely locked and do not rotate. Furthermore, the motor 25 or the wheels have built-in encoders, so that the moving distance of the self-propelled vehicle 20 can be detected.
FIG. 4 is an enlarged view of the AA cross section in FIG. The chassis 21 has magnets 27 attached near the four wheels. The magnet 27 is attached to the chassis 21 at a predetermined distance from the steel object to be cut, approximately several mm in this embodiment, so as not to create resistance during running. The magnet 27 of this embodiment uses a magnet, such as a neodymium magnet, that can obtain an attractive force even if it is not brought into direct contact with the object to be cut but is spaced apart by a predetermined distance.
Near the center of the chassis 21 is provided an elongated cutting opening 28 having a space through which the end mill 32 of the direct-acting cutting section 30 can move in the cutting direction.

(Direct acting cutting section 30)
FIG. 3 is a perspective view of the direct acting cutting section. As shown in the figure, the direct-acting cutting section 30 includes an end mill 32 that can cut steel objects without flames, and a blade of the end mill 32 in a direction perpendicular to the main surface of the object (the direction of the object to be cut). The first linear motion mechanism 34 moves forward and backward in the thickness direction (arrow a in FIG. 3) to cut, and the blade of the end mill 32 moves linearly on the main surface of the object to be cut (arrow a in FIG. 3). b) A second linear motion mechanism 40 is provided.
The first linear motion mechanism 34 and the second linear motion mechanism 40 include an end mill 32 on one main surface, a first linear guide 37a on the other main surface, and a first slider that slides on the first linear rail 35a. 39a (see FIG. 2), a first feed screw 36a to which a first linear guide 37a is screwed on one main surface, and a pair of first linear rails 35a; A second frame 34b on a flat plate is provided with a second slider 39b (see FIG. 2) that slides a second linear rail 35b on its main surface, and a first feed screw 36a connected to the upper surface of the second frame 34b. A flat third frame 34c equipped with a second linear guide (not shown) screwed into the first drive motor 38a and the second feed screw, a second linear rail 35b on the side surface, and a second feed screw 36b on the top surface. It is attached to a prismatic fourth frame 34d having a second drive motor 38b.
A pair of first linear rails 35a are arranged at both ends between the first and second frames 34a and 34b, and a first feed screw 36a is arranged between them (at the center), so that the longitudinal direction is relative to the main surface of the chassis 21. It is attached along the direction (arrow a in FIG. 3) perpendicular to the direction shown in FIG.
With such a configuration, the first linear motion mechanism 34 allows the first frame 34a to advance and retreat in the vertical direction (thickness direction of the object to be cut) from the second frame 34b as a starting point when the first drive motor 38a is rotated forward or backward. do. Accordingly, the blade of the end mill 32 attached to the first frame 34a can cut into the object to be cut.
Further, in the second linear motion mechanism 40, when the second drive motor 38b is rotated forward or reverse, the first to third frames 34a, 34b, and 34c move forward and backward in the longitudinal direction of the frames with the fourth frame 34d as a starting point. Accordingly, the blade of the end mill 32 attached to the first frame 34a can cut the object in a straight line along the linear rail.
The first and second linear motion mechanisms 34 and 40 have a built-in limit switch (not shown) that stops the end mill 32, which moves vertically and horizontally, at the mechanical end or at an appropriate position, and when the limit switch is activated, the end mill 32 moves vertically and horizontally. A configuration is adopted in which movement on either the left or right side is stopped.

FIG. 5 is an explanatory diagram of wall running of the self-propelled vehicle. As shown in FIG. 1 (1), the driving force of the self-propelled traveling body 20 is F1, the rolling friction resistance between the wheels and the running surface (the surface of the object to be cut) is F2, and the running weight is M. Let g be the total mass M including the direct-acting cutter 30, and the gravitational acceleration be g, and let F3 be the static frictional force between the wheel and the running surface (frictional force that acts to prevent the wheel from starting to move). Here, in order for the self-propelled traveling body 20 to ascend the wall surface, it is necessary for the driving force F1 generated by the motor of the traveling body to overcome the rolling resistance F2 of the traveling body and the weight M.g of the traveling body (drive Force F1>Rolling friction resistance F2+Running weight M.g). Furthermore, in order to transmit the driving force F1 to the running surface without causing the wheels to slip, the static frictional force F3 needs to be larger than the driving force F1 (static frictional force F3>driving force F1).
Here, driving force F1=T/r・n・A (T: rated torque of motor, r: wheel radius, n: mechanical efficiency, A: number of motors), rolling friction resistance F2=μ1・N (μ1: wheel can be expressed as rolling friction coefficient, N: vertical resistance (reaction force of magnetic force) received by the wheel, and static friction force F3=μ2·N (μ2: static friction coefficient of the wheel).
As an example, if T=75Nm, r=0.05m, n=0.7, and A=2 units, then F1=2100N.
FIG. 5(2) is a graph obtained by calculating the change in the attraction force (N) of the magnet used in this embodiment, using the separation distance (mm) between the magnet and the attraction surface as a parameter. For example, when the separation distance is 7 mm, the adsorption force is 1754N. Since four magnets are used in this embodiment, the attraction force on the running surface of the self-propelled running body 20 is 1754N×4=7016N. Therefore, if all of this adsorption force is received by the wheels, the vertical reaction force N that the wheels receive from the adsorption surface is 7016N. Therefore, when the rolling friction resistance μ1 is set to 0.01, the rolling friction resistance F2 of the traveling body is 70N.
Further, if the mass of the traveling body is 70 kg, M.g=70×9.8=686N.
Further, assuming that the static friction coefficient μ2 of the wheels (wheels (rubber) and walls (steel)) is 0.5, F3 is 3508N.
Then, F1-F2-M・g>0, 2100N-70N-686N=1344N>0, and F3-F1>0, 3508N-2100N=1408N>0, so self-propelled The running body can run on a wall surface.

FIG. 6 is an explanatory diagram of cutting resistance while the self-propelled vehicle is stopped. When the self-propelled traveling body 20 is stopped (locked by the motor or wheel brake) and the direct-acting cutting section 30 cuts, the cutting resistance generated in a plane parallel to the cutting surface is in the feeding direction of the end mill. The force F4 is the force F5, and the force F5 is the force F5 in the direction perpendicular to the feed. In the range where the resultant force of these cutting forces F4 and F5 and the device weight M.g is smaller than the static friction force F3 of the self-propelled traveling body 20, the self-propelled traveling body 20 can remain at the stopped position and will not cut or turn. It can be considered that this does not occur (F3>F4+F5+M.g). Figure (2) shows an example of the relationship between the cutting resistance (N) generated when cutting a 22 mm thick steel plate with a Φ12 mm roughing end mill (end mill rotation speed 750 rpm) and the feed rate (mm/min). In addition, Figure (3) shows the relationship between the total external force applied to the device during cutting work (the vector sum of the cutting resistances F4 and F5 shown in Figure (2) and the device weight M.g) and the end mill feed speed. It is something that As shown in the figure, the total value of the external forces becomes approximately equal to the static friction force F3 (3508 N) of the self-propelled traveling body 20 when the end mill feed rate is approximately 50 mm/min. Therefore, if the feed rate is lower than 50 mm/min, the cutting operation can be performed without causing the device to fall or bend.

[Remote disconnection method]
A remote cutting method using the remote cutting device of the present invention having the above configuration will be described below. FIG. 1 is an explanatory diagram of the remote cutting method of the present invention.
(Step 1)
After the self-propelled traveling body 20 is attracted to the outer plate and moved to the cutting start position S, it is stopped (see FIG. 1(a)).
(Step 2)
The first linear motion mechanism 34 causes the blade of the end mill 32 to cut into the object to be cut in the thickness direction. The limit switch is activated at an appropriate position (depth) and the downward cutting is automatically stopped (see Figure 1(a)).
(Step 3)
Next, the second linear motion mechanism 40 cuts the end mill 32 linearly along the longitudinal direction of the second linear rail 35b by a cutting stroke (the moving length of the second linear guide on the second linear rail 35b). When the second linear guide moves to the mechanical end of the second linear rail 35b, the limit switch is activated and automatically stops (see FIG. 1(b)).
(Step 4)
The second linear motion mechanism 40 is sent (moved) in the opposite direction to the cutting start position S. Similarly, when the second linear guide moves to the mechanical end of the second linear rail 35b, the limit switch is activated and automatically stops (see FIG. 1(c)).
(Step 5)
The self-propelled traveling body 20 is moved straight by a cutting stroke (cutting length). An encoder in the motor 25 or the wheels detects the moving distance of the traveling body corresponding to the stroke and automatically stops the motor 25 or the wheels.
Steps 2 to 5 above are repeated until the cutting end position of the object to be cut is reached.

After adhering to the outer plate of a large tank in this way and cutting the end mill in the thickness direction of the plate, the end mill is sent by the other linear motion mechanism to cut the body plate. Thereafter, the end mill is once returned to the cutting start position by the linear motion mechanism, and then the traveling body is advanced to the cutting end position. After moving the running body forward, the end mill is sent again to cut. In this way, cutting and running are repeated alternately. During the cutting operation, the self-propelled traveling body adheres to the wall surface of the object to be cut, thereby suppressing the cutting reaction force exerted by the direct-acting cutting section and allowing the object to be cut in a straight line without bending.
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
Further, the present invention is not limited to the combinations shown in the embodiments, but can be implemented by various combinations.

20 Self-propelled traveling body 21 Chassis 22a, 22b Front wheels 22c, 22d Rear wheel 23 Shaft 24 Bearing 25 Motor 26 Chain 27 Magnet 28 Cutting opening 30 Direct-acting cutting section 32 End mill 34 First linear-acting mechanism 34a, 34b, 34c , 34d First to fourth frames 35a, 35b First and second linear rails 36a, 36b First and second feed screws 37a First linear guides 38a, 38b First and second drive motors 39a, 39b First and second 2 slider 40 second linear motion mechanism

Claims (2)

A self-propelled traveling body equipped with a direct-acting cutting section that cuts with an end mill along a linear rail and a magnet that attracts the steel object to be cut is adsorbed to the object to be cut and travels to a cutting start position; ,
A cutting step of cutting linearly along the linear rail from the cutting start position with the direct-acting cutting unit while the self-propelled traveling body is stopped, and returning to the cutting start position after cutting;
a moving step of moving with the self-propelled traveling body by the length cut by the direct-acting cutting section;
A remote cutting method comprising: repeating the cutting step and the moving step until the object to be cut is cut. A self-propelled traveling body that has wheels and magnets at the four corners of a chassis and travels while adhering to a steel object to be cut at a predetermined interval with the magnets;
a direct-acting cutting section that includes a linear rail and a long hole in which the end mill moves along the advance/retreat direction in the center of the chassis, and cuts the object to be cut in a straight line along the linear rail;
The cutting resistance generated in a plane parallel to the cutting surface of the end mill of the direct-acting cutting section that cuts while the self-propelled traveling body is stopped is a force F4 in the feed direction of the end mill and a force F5 in a direction perpendicular to the feed. The end mill is set at a feed rate that satisfies F3>F4+F5+M.g, where the weight of the self-propelled traveling body is M.g and the static frictional force of the self-propelled traveling body is F3. Cutting device.

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