JPH082512B2 - Laser welding equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laser welding apparatus suitable for end welding of a fuel rod used in a nuclear reactor.

[Prior Art] For example, a fuel rod used in a nuclear reactor such as a pressurized water type light water reactor is one in which a large number of fuel pellets are housed inside a cladding tube and both ends thereof are closed by end plugs. High-pressure helium gas is sealed inside so that the cladding tube does not lose pressure in the reactor.

Here, when enclosing helium gas in the cladding tube, a hole communicating with the inside and outside of the cladding tube is formed in one end plug, and the hole of the end plug is laser-welded in a high-pressure helium gas atmosphere. I am trying to close it. Conventionally, a laser welding device for performing such welding is one in which a glass window is provided in a chamber having a pressurizing chamber inside, and a fuel rod is inserted into the chamber and its end plug is placed in the pressurizing chamber. No, it is configured to weld the hole of the end plug by the laser light passing through the glass window.

[Problems to be Solved by the Invention]

By the way, when the laser welding device as described above is used, the metal vapor generated by the welding becomes soot and gradually adheres to the glass window. Therefore, there is a problem that such soot is melted by the laser light and the glass window is melted or damaged by the heat.

[Object of the Invention] The present invention has been made in order to solve the above problems, and can prevent soot of metal vapor from adhering to a glass window. Therefore, melting or damage of the glass window can be prevented. It is an object of the present invention to provide a laser welding device capable of preventing the occurrence of the phenomenon.

[Means for Solving the Problem] The laser welding apparatus of the present invention is configured by providing a partition having a through hole through which a laser beam passes, in the middle of both ends of the pressurizing chamber.

[Operation] The soot of metal vapor generated by welding becomes difficult to move to the window side due to the presence of the partition. Further, when the soot enters the light flux of the laser light, it is heated by the laser light, ionizes and actively moves, and is scattered outside the light flux. Therefore, the soot is also prevented from moving to the window side through the through hole of the partition.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a plan sectional view showing a laser welding apparatus of an embodiment, and FIG. 2 is a view taken in the direction of arrow II in FIG.

In these figures, reference numeral 1 is a base. A hydraulic cylinder 2 having a piston rod 2a directed leftward in the drawing is attached to the center of the base 1. An index case 3 is fitted on the piston rod 2a of the hydraulic cylinder 2. Index case 3, as shown in FIG.
A flange 3a having a diameter larger than that of the other end 3b is formed at one end, and the outer circumference of the other end 3b is N
Grooves 4 are formed which are continuous with each other at a pitch of 60 °. The index case 3 is fitted in a cylinder 5 attached to the hydraulic cylinder 2 so as to be relatively rotatable. Tube 5
, A plurality of pins 6 whose axes are directed in the radial direction are arranged at equal intervals in the circumferential direction. The pin 6 is biased toward the center by a coil spring 7, and its tip end is engaged with the groove 4 of the index case 3. As a result, the index case 3 rotates 60 ° clockwise along the groove 4 by extending the piston rod 2a.

Further, a window mount 8 having a central portion penetrated by a piston rod 2a is attached to the flange 3a of the index case 3, and a nut 9 attached to a tip portion of the piston rod 2a is tightened to the index case 3 side. , So as not to rotate relative to the piston rod 2a. Therefore, the wind mount 8 is adapted to rotate together with the index case 3 and the piston rod 2a by extending the piston rod 2a.

The wind mount 8 has a disk shape, and six glass windows 10 are fitted on its end face at equal intervals in the circumferential direction. FIG. 3 is a plan view showing the wind mount 8. In the figure, reference numeral 11 is a fixture for attaching the window 10 to the wind mount 8, and a hole 11a for passing laser light is formed in the center thereof.

On the other hand, a chamber 20 is attached to the base 1. Cylindrical holes 21 and 22 are formed at both ends of the chamber 20, and the cylindrical holes 21 and 22 are communicated with each other by a communication hole 23. In the cylindrical hole 21 on the left side, two cylindrical bodies 2
4,25 are fitted. The tubular bodies 24 and 25 are cylindrical with a bottom, and through holes 24a and 25a are formed in their bottoms (see FIG. 5). Further, the inner surface of the bottom (partition) 24b of the cylindrical body 24 on the left side is formed in a tapered shape whose diameter gradually decreases toward the right side. The inner space of these cylindrical bodies 24, 25 is defined as a pressurizing chamber 26, and the pressurizing chamber 26
Is the first and second chambers 26a, 26b due to the bottom 24b of the left tubular body 24.
It is divided into Reference numeral 27 is a screw for fixing the tubular bodies 24, 25.

Further, a plurality of holes 28 are formed in the outer peripheral wall of each tubular body 24, 25. On the other hand, a concave portion 21a is formed on the inner circumference of the cylindrical hole 21 so as to surround the hole 28. And chamber 2
At 0, an intake port 29 and an exhaust port 30 communicating with each recess 21a are formed.

Next, in the cylindrical hole 22 on the right side, spacers 31, 31, packings 32 arranged so as to be sandwiched by these spacers 31, 31, and thrust bearings 33 are fitted. Also, on the right side of the thrust bearing 33, a screw member
34 is screwed, and a lock nut is attached to the outer periphery of the screw member 34.
35 is screwed. And the spacer 31, packing
The fuel rod A is inserted through the central portions of the thrust bearing 33 and the screw member 34.

The right end surface of the wind mount 8 is pressed against the left end portion of the chamber 20 thus configured, and in this state, the axis line of the window 10 and the axis line of the fuel rod A are aligned with each other. Reference numeral 38 is an O-ring for airtightly closing the gap between the wind mount 8 and the chamber 20.

In addition, a mount receiver 39 is provided on the base 1 and a pressing cylinder 2 is provided.
It is attached to the opposite side of the chamber 20 with the sandwiched between.
The mount receiver 39 supports the window mount 8 so that a bending moment does not act on the piston rod 2a of the hydraulic cylinder 2 due to the pressure in the pressurizing chamber 26, and also the window 10
Is to clean the end face of the, and a rotating brush or the like is disposed inside thereof.

Next, the operation of welding the end portion of the fuel rod A by the laser welding device will be described.

First, the fuel rod A is inserted into the screw member 34, and the left end portion thereof is brought into contact with the edge portion of the hole 25a of the tubular body 25. next,
With the end surface of the wind mount 8 pressed against the end surface of the chamber 20, the air in the pressurizing chamber 26 is exhausted from the exhaust port 30 to make the inside of the pressurizing chamber 26 and the fuel rod A substantially vacuum. Next, helium gas is fed from the intake port 29 into the pressurizing chamber 26,
As a result, the inside of the fuel rod A is replaced with helium gas, and the pressure in the pressurizing chamber 26 is set to, for example, about 35 atmospheres.

Next, laser light (shown by a chain double-dashed line in FIG. 1) is irradiated by a laser light generation mechanism (not shown). The laser light is focused by the lens 40, passes through the window 10, and is irradiated to the end portion of the fuel rod A. The laser light causes the light formed on the end plug of the fuel rod A to be welded and closed. At this time, vapor of metal is generated and becomes soot, but the bottom 24 of the tubular body 24
The presence of b makes it difficult to move to the window 10 side. Further, when soot enters the light flux of the laser light, it is heated by the laser light, ionizes and actively moves, and is scattered outside the light flux. Therefore, the soot is also prevented from moving to the window 10 side through the light 24a of the tubular body 24.

Next, the helium gas in the pressure chamber 26 is discharged to the outside through the exhaust port 30. At this time, since the helium gas flows from the first chamber 26a to the second chamber 26b side, the soot that has moved to the first chamber 26a side moves to the second chamber 26b side. In addition, the bottom of the tubular body 24 of the first chamber 26a
Since the inner surface of 24b is formed in a tapered shape, the soot can be smoothly moved.

Next, when the pressure in the pressurizing chamber 26 reaches the atmospheric pressure, the piston rod 2a of the hydraulic cylinder 2 is extended. Then, the index case 3 rotates by 60 ° along the groove 4, and accordingly, the wind mount 8 and the piston rod 2a also rotate. Next, the piston rod 2a is contracted to press the window mount 8 against the end surface of the chamber 20, and the same process as above is performed. Further, while the fuel rod A is being welded at the end in this manner, the window 10 is cleaned in the mount receiver 39.

In the laser welding device, the bottom 24b of the tubular body 24
As a result, the soot is less likely to move to the window 10 side, so it is possible to reduce the adhesion of soot to the window 10 and prevent melting or damage of the window 10 in advance.

Further, the intake port 29 is located on the first chamber 26a side, and the exhaust port 30 is located on the second chamber 2a.
Since it is arranged on the 6b side, the soot in the first chamber 26a is returned to the second chamber 26b every time the end welding of the fuel rod A is completed, so that the window 10
Soot can be further reduced. Moreover, since the plurality of windows 10 are used in order while rotating the wind mount 8 and cleaned by the mount receiver 39 each time the window 10 is used once, even if a slight amount of soot is attached to the window 10, the window 10 can be immediately cleaned. Can be paid off. Therefore, it can be used continuously for a long time without maintenance.

In the above embodiment, the pressurizing chamber 26 has the first chamber 26a and the second chamber 26a.
Although it is divided into the chamber 26b, the movement of the soot toward the window 10 side can be further reduced by dividing into a larger number of chambers. Further, the inner walls of the tubular bodies 24 and 25 may be formed in a wavy shape or a labyrinth shape.

[Effects of the Invention] As described above, in the laser welding apparatus of the present invention, the pressurizing chamber is provided with a partition having a through hole for passing laser light at an intermediate portion between both ends thereof. It is possible to reduce the soot of the generated metal vapor from moving to the window side. Therefore, it is possible to prevent the melting and damage of the window due to the soot adhesion from occurring.

[Brief description of drawings]

1 to 5 are views showing an embodiment of the present invention, in which FIG. 1 is a plan sectional view showing a laser welding apparatus, FIG. 2 is a view in the direction of arrow II in FIG. 1, and FIG. FIG. 4 is a plan view showing the wind mount, FIG. 4 is a side view showing the index case, and FIG. 5 is a plan sectional view showing details of the chamber. 10 ... Window, 20 ... Chamber, 26 ... Pressurizing chamber, 24a ... Through hole, 24b ... Bottom (partition).

Claims (1)

[Claims] 1. An opening communicating with one end of the pressurizing chamber is provided at one end of a chamber having a pressurizing chamber therein, and the opening is hermetically closed and pressurized from the outside of the chamber. A window is provided through which the laser beam applied to the other end of the chamber passes, and the other end of the chamber is hermetically inserted into the welded body so that the welded end of the body to be welded is A laser welding apparatus having a hole facing an end thereof, characterized in that a partition having a through hole through which the laser hole passes is provided at an intermediate portion of both ends of the pressurizing chamber.