JP4664578B2 - Welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welding apparatus for welding a nozzle base of a reactor pressure vessel and a control rod drive mechanism housing in a nuclear power plant in operation.
[0002]
[Prior art and problems to be solved by the invention]
2. Description of the Related Art A welding apparatus having a chamber function has been developed when welding a reactor pressure vessel nozzle and a control rod drive mechanism housing (hereinafter simply referred to as a housing). However, if this welding device is removed due to trouble, the welded part will be submerged in water, so additional work such as drying will be required, and if water remains, a welding defect will occur. Was more likely to occur. In addition, since this welding apparatus performs welding based on the outer periphery of the nozzle, there is a drawback that it is difficult to control the axis of the housing to coincide with the axis of the nozzle.
[0003]
It should be noted that the above-mentioned drawbacks can be eliminated by adopting a seal pipe system in which the pipe is lowered to the outside of the welded portion where the nozzle and the housing are welded and the water inside the pipe is removed. However, this seal pipe method has been applied to work other than welding, but has not been applied to welding. The reason is that since the gap between the seal pipe and the nozzle is small, various functions are required to perform high-quality welding remotely, and it is difficult to make the welding head compact.
[0004]
The present invention has been made to solve the above-described problems, and its purpose is to weld the nozzle and the housing in a locally dry type even when there is water in the reactor pressure vessel in an operating nuclear power plant. It is to provide a welding apparatus that enables it.
[0005]
Another object of the present invention is to provide a welding apparatus that realizes compactness that enables welding in a narrow space such as a seal pipe for local drying.
[0006]
[Means for Solving the Problems]
The invention according to claim 1
A control rod drive mechanism housing is inserted inside a cylindrical nozzle provided so as to protrude vertically upward through the bottom of the reactor pressure vessel, and the nozzle and the control rod drive mechanism housing are covered with a seal pipe. A welding device that isolates the water from the reactor pressure vessel and welds the nozzle and the control rod drive mechanism housing;
A transfer base inserted into the seal pipe;
A fixed pressing base, a clamp mechanism and a downward swing provided via a rotation mechanism at the bottom of the transfer base;
A welding torch provided between the transfer base and the rotation mechanism, and capable of moving up and down via a slide shaft;
The clamp mechanism clamps the upper part of the control rod drive mechanism housing to fix the transfer base to the control rod drive mechanism housing;
The plumb, the welding apparatus is suspended from a position through which the axis of its to said tube under the base end portion in and to allow check coincidence between the axis of the welding device and the tube stand axis It is characterized by that.
[0007]
According to a second aspect of the present invention, in the welding apparatus according to the first aspect, the welding torch includes a monitoring device that monitors at least one of a set state of the electrode position before welding and a state of the molten pool during welding.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on a preferred embodiment shown on a screen. FIG. 1 is a schematic configuration diagram showing a cross section of a main part of an embodiment of a welding apparatus according to the present invention. In the figure, the nozzle 1 passes vertically through the bottom of a reactor pressure vessel (not shown), and its upper end is shown. In inserting the housing 2 into the nozzle 1 and welding the upper end of the nozzle 1 and the outer peripheral surface of the housing 2, the seal pipe 3 is lowered vertically so as to cover the periphery of the nozzle 1, With the lower end pressed against the bottom of the reactor pressure vessel, the water inside the seal pipe 3 is extracted. In this state, the welding apparatus 10 is inserted into the seal pipe 3 from the upper end thereof.
[0013]
The welding apparatus 10 includes a transfer base 11 for holding and transferring the welding apparatus 10. The transfer base 11 is integrally assembled by a rod 11e with a holding plate 11a and a mounting plate 11c interposing a reinforcing plate 11b, and the mounting plate 11c and the mounting plate 11d have a predetermined interval. In this state, they are coupled by the slide shaft 11f. The slide shaft 11f is provided at a position obtained by dividing the circumferential direction into three equal parts, and a welding torch mounting base 12 is mounted on the slide shaft 13 so as to be reciprocally movable along the slide shaft 11f.
[0014]
A ball nut 14 and a ball screw 15 for moving the welding torch mounting base 12 in the vertical direction are provided on the shaft core portion of the welding torch mounting base 12. Among these, the ball nut 14 is fixed to the welding torch mounting base 12, and the upper end portion of the ball screw 15 is rotatably supported by a radial ball bearing with its end protruding upward, and the lower end of the ball screw 15. The part is rotatably held by a radial ball bearing.
[0015]
A mounting base 16 is fixed to the upper surface of the mounting plate 11c, and an axial driving mechanism 17 including an electric motor is mounted on the mounting base 16. The axial drive mechanism 17 is constituted by a reduction mechanism including an electric motor, a bevel gear, a worm and a worm wheel. With this configuration, the welding torch mounting base 12 can be moved up and down by driving the electric motor. Moreover, since this embodiment employs TIG welding, the wire feeding mechanism 18 for guiding the welding wire to the welded portion does not hinder the movement of the welding torch mounting base 12 below the mounting plate 11c. Mounted in position.
[0016]
A fixed pressing base 22, a clamp mechanism 23, and a downward swing 24 are mounted on the lower surface portion of the mounting plate 11 d constituting the transfer base 11 via a rotation mechanism 21. Of these, the fixed pressing base 22 has a conical pressing surface that presses against the inner edge of the upper end of the housing 2 and aligns the axis of the housing 2 with the axis of the rotation mechanism 21. In order to confirm that the transfer base 11 is placed on the upper end of the housing 2, a contact sensor (not shown) is provided at a position obtained by dividing the circumferential direction into three equal parts. The clamping mechanism 23 has a function of pressing an inward projection 2a that protrudes in an annular shape radially inward from the upper end of the housing 2 toward the fixed pressing base 22 side by driving a mechanism similar to a pantograph with an air cylinder. It has. In this way, the fixed pressing base 22 is fixed to the housing 2 by sandwiching the inward protrusion 2 a by the fixed pressing base 22 and the clamp mechanism 23. The rotation mechanism 21 has a built-in mechanism for rotating the welding apparatus 10 with respect to the fixed pressing table 22. The downward swing 24 is suspended to the lower end portion of the nozzle 1 (not shown), so that it can be confirmed whether or not the axis of the welding apparatus 10 matches the axis of the nozzle 1. Yes.
[0017]
On the other hand, a radial movement mechanism 31 for moving the welding torch portion 34 in the radial direction is mounted on the lower surface of the welding torch mounting base 12 at a position off the axis. The radial movement mechanism 31 includes an encoder (not shown) that monitors its position. In place of the encoder, a magnetic encoder or resolver that functions even under high radiation may be used. An AVC (Automatic Voltage Control) mechanism 32 for stabilizing the arc during welding is attached to the lower surface of the radial movement mechanism 31. The AVC mechanism 32 has an oblique mounting surface on the radially outer side, and a welding torch portion 34 including a wire nozzle (not shown) and a CCD camera 35 is mounted on the mounting surface via a torch angle adjusting mechanism 33. . The CCD camera 35 monitors the movement and set position of the welding torch part 34, and a potentiometer is used for the angle display of the torch angle adjusting mechanism 33.
[0018]
In addition to the handle for transferring the transfer base 11, the holding plate 11a includes a connector for providing electrical wiring, a piping terminal for introducing pressurized air, and the like, and the cable 8 led out from the control device 4 is coupled to the connector. Then, the operation for attaching the welding power source 5 and the cylinder 6 and the hose 9 led out from the monitoring device 7 are coupled to the piping terminal. The control device 4 and the welding power source 5 are connected by a cable 8.
[0019]
The operation of the present embodiment configured as described above will be described below. With the water present in the reactor pressure vessel, the seal pipe 3 is lowered from above the water surface to the bottom, the lower end surface is pressed against the bottom of the reactor pressure vessel, and the nozzle 1 to be welded is another nozzle Isolate from. Then, the water inside the seal pipe 3 is drained. In this case, since the interval between the adjacent nozzles is determined, the inner diameter of the seal pipe 3 is suppressed to a nominal 100 millimeters (mm) with respect to the outer diameter of the nozzles 1. That is, the clearance between the outer peripheral surface of the nozzle 1 and the inner peripheral surface of the seal pipe 3 is nominally 50 millimeters (mm). At this time, if the installation error (center misalignment) of the seal pipe 3 is 5 millimeters (mm), the clearance is 45 millimeters, and not only the parts constituting the welding torch part 34 are made compact, but also the radial driving is performed. The stroke of the drive mechanism having the components, that is, the radial movement mechanism 31 and the torch angle adjustment mechanism 33 is shortened to, for example, about 35 millimeters (mm), and the movement and setting position are confirmed and monitored by an encoder or a potentiometer. I do.
[0020]
Next, the upper part of the holding plate 11 a is gripped by a transport device (not shown), and the welding device 10 is inserted into the seal pipe 3. As a result, when the contact sensor (not shown) senses that the lower surface of the fixed pressing base 22 is placed on the housing 2, the clamp mechanism 23 sandwiches the inward projection 2 a by the control signal of the control device 4, and the fixed pressing base 22 22 and the housing 2 are fixed integrally. At this time, the downward swing 24 extends from the lower end of the nozzle 1, and whether or not the axis of the nozzle 1 and the axis of the welding apparatus 10 coincide with each other, that is, the housing to which the fixed pressing table 22 is fixed. Whether or not 2 is tilted can be monitored.
[0021]
Next, the operation and monitoring device 7 and the control device 4 are used to move the torch angle adjustment mechanism 33 radially outward by driving the radial movement mechanism 31 while monitoring the welding target position with the CCD camera 35. By driving the axial direction drive mechanism 17, the welding torch mounting base 12 is lowered, and further by driving the torch angle adjusting mechanism 33, the angle of the welding torch part 34 is adjusted and held in a weldable state. Also, the wire feed mechanism 18 feeds the tip of the wire to the welding position.
[0022]
When the welding operation is started in this state, the upper end of the nozzle 1 and the outer peripheral surface of the housing 2 are welded with one end of the housing 2 protruding upward from the upper end of the nozzle 1. At this time, the welding pool is monitored by the CCD camera 35.
[0023]
Next, by driving the rotation mechanism 21 using the operation and monitoring device 7 and the control device 4, the entire welding device 10 is rotated around the axis of the housing 2, and the entire circumference of the nozzle 1 is rotated. Then, the housing 2 is welded.
[0024]
After completing the series of welding operations, the welding torch part 34 is lifted, stored radially inwardly, the clamping mechanism 23 is released, and the welding pipe 10 from the seal pipe 3 is operated in the reverse manner as described above. An extraction operation is performed.
[0025]
Thus, according to the present embodiment, the nozzle 1 is isolated from the water in the reactor pressure vessel by the seal pipe 3, the internal water is excluded, and the upper end of the nozzle 1 and the outer peripheral surface of the housing 2 are welded. As a result, the nozzle and housing can be welded in a locally dry manner even when there is water in the reactor pressure vessel at the nuclear power plant in operation.
[0026]
Also, a transfer base 11 that can be inserted and removed from the upper end of the seal pipe, a clamp mechanism 23 with a rotating mechanism mounted on the lower surface thereof, and a welding torch mounting base that is driven in the axial direction by an axial drive mechanism 17. 12 and a welding torch portion mounted on the welding torch mounting base 12 via the radial direction moving mechanism 31, a compact design that enables welding in a narrow space inside the seal pipe is realized. The
[0027]
In the above-described embodiment, the CCD camera 35 for mainly monitoring the welding pool is provided in the vicinity of the torch angle adjusting mechanism 33. However, in order to monitor the welding target portion, the installation position of the welding torch portion 34 and It is also possible to provide more CCD cameras, such as providing them at positions opposite to each other by 180 degrees.
[0028]
【The invention's effect】
As is apparent from the above description, according to the present invention, a welding apparatus that enables welding between a nozzle and a housing in a locally dry type even when there is water in a reactor pressure vessel in an operating nuclear power plant. Is provided. In addition, a welding apparatus that realizes compactness that enables welding in a narrow space such as a seal pipe for local drying is provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a cross section of a main part of an embodiment of a welding apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pipe stand 2 Housing 3 Seal pipe 4 Control apparatus 7 Operation, monitoring apparatus 10 Welding apparatus 11 Transfer base 12 Welding torch mounting base 17 Axial drive mechanism 18 Wire feed mechanism 21 Rotating mechanism 22 Fixed pushing base 23 Clamp mechanism 24 Lowering Swing 31 Radial movement mechanism 32 AVC mechanism 33 Torch angle adjustment mechanism 34 Welding torch part

Claims (3)

A control rod drive mechanism housing is inserted inside a cylindrical nozzle provided so as to protrude vertically upward through the bottom of the reactor pressure vessel, and the nozzle and the control rod drive mechanism housing are covered with a seal pipe. A welding device that isolates the water from the reactor pressure vessel and welds the nozzle and the control rod drive mechanism housing;
A transfer base inserted into the seal pipe;
A fixed pressing base, a clamp mechanism and a downward swing provided via a rotation mechanism at the bottom of the transfer base;
A welding torch provided between the transfer base and the rotation mechanism, and capable of moving up and down via a slide shaft;
The clamp mechanism clamps the upper part of the control rod drive mechanism housing to fix the transfer base to the control rod drive mechanism housing;
The downward swing is suspended from the position where the axis passes through the welding apparatus to the lower end of the nozzle, and it is possible to confirm the coincidence between the axis of the nozzle and the axis of the welding apparatus. Features welding equipment. The welding apparatus according to claim 1, wherein the welding torch includes an observation device for monitoring at least one of a setting state of an electrode position before welding and a state of a molten pool during welding.   The clamp mechanism has a conical pressing surface that presses against the inner edge of the upper end of the control rod drive mechanism housing and aligns the axis of the control rod drive mechanism housing with the axis of the rotation mechanism. The welding apparatus according to claim 1 or 2.

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