JP2013066910A - Gas shield body and underwater repair welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas shield body that can hold a welding area and its proximity in a dry atmosphere no matter whether the face to be repaired is smooth or not, and to perform preferable underwater repair welding; and to provide an underwater repair welding apparatus.SOLUTION: An underwater repair welding apparatus performs the underwater repairing of an underwater construction S by laser welding, which is equipped with: a laser oscillator 2; a laser welding head 7 having a condensing part 5 condensing the laser light L oscillated by the laser oscillator 2 and irradiating the underwater construction S with the laser light; a nozzle 6 located at the distal end of the laser welding head 7, and feeding a shield gas G to the welding area coaxially with the laser light L; and a gas shield body 11 equipped with a shield body body 12 disposed in the nozzle 6, and having a plurality of gas-holding spaces 13. The shield body body 12 is equipped with: a contact face 14 having contact with the cover plate 20 and sliding so as to absorb unevenness on the cover plate 20; and a through-hole 15 whose one side is fitted with the distal end of the nozzle 6 and the other end opens at the contact face 14.

Description

  The present invention relates to a gas shield body and an underwater repair welding apparatus that are used to locally make a welded part or its vicinity a dry environment when irradiating a laser beam to the underwater structure to repair the underwater structure. Is.

  When a defect such as a weld defect or stress corrosion cracking occurs in an underwater structure, for example, an in-water structure of a nuclear reactor or a lining of a spent fuel storage pool, the defect is completely removed by a grinder or electric discharge machining. After that, it is desirable to repair the recess formed by removing the defective portion by overlay welding.

  Since the repair work for removing the defective part takes a lot of time, an effective repair method is to cover the defective part generated in the in-furnace underwater structure with a curing plate, for example. There is known an underwater repair welding method in which a defect portion is isolated from furnace water or pool water by performing fillet welding of the peripheral portion of the curing plate by laser welding while supplying it.

  At this time, it is necessary to locally set the vicinity of the welded portion as a dry environment. Conventionally, as a technique having a technique for ensuring a local dry environment near the welded portion, for example, Patent Document 1 describes. There are underwater repair welding equipment.

  This underwater repair welding apparatus has a laser welding head having a condensing part for condensing laser light oscillated by a laser oscillator to an appropriate size and irradiating the underwater structure, and is located at the tip of the laser welding head. A nozzle for supplying a shielding gas coaxially with the laser beam to the welded portion, and a shield box installed on the nozzle are provided. The shield box surrounds the welded portion and opens on the welded portion side. It consists of the elastic body attached to the opening peripheral part of a box.

  In this underwater repair welding device, the welded surface of the shield box filled with the shield gas supplied through the nozzle is brought into contact with the surface to be welded, so that water in the welded portion is eliminated during laser welding. A local dry environment in a part or its vicinity is secured.

Japanese Patent No.4363933

  However, in the conventional underwater repair welding apparatus described above, a shield gas is continuously supplied to a shield box in which an elastic body is in contact with a surface to be welded via a nozzle, so that a welded portion or a dry environment in the vicinity thereof is provided. If there is a slight gap between the elastic body and the surface to be welded, such as when the elastic body passes through the unevenness on the surface to be welded. Has a problem that there is a possibility that the welded part or the dry environment in the vicinity of the welded part may be damaged, and it has been a conventional problem to solve this problem.

  The present invention has been made paying attention to the above-mentioned conventional problems, and when performing underwater repair welding, not only when the welded surface is smooth, even if there are irregularities on the welded surface, An object of the present invention is to provide a gas shield body capable of maintaining a welded portion or its vicinity in a dry atmosphere and, as a result, capable of performing excellent repair welding, and an underwater repair welding apparatus including the gas shield body.

  In order to achieve the above object, the invention according to claim 1 of the present invention provides a gas shield body that keeps a welded portion on a surface to be welded or its vicinity in a dry atmosphere when repairing an underwater structure by laser welding. A shield body having a large number of gas holding spaces, the shield body having a contact surface that contacts the welded surface and slides so as to absorb irregularities on the welded surface; There is a through hole in which at least the tip of a nozzle for supplying a shielding gas such as argon gas, helium gas or nitrogen gas is fitted to one end side coaxially with the laser beam irradiated to the welded portion and the other end opens at the contact surface The gas shield body having this configuration is used as a means for solving the above-described conventional problems.

  Moreover, the gas shield body according to claim 2 of the present invention is configured to include a floating restraining means for restraining the shield body from floating in water.

  On the other hand, an invention according to claim 3 of the present invention includes a laser oscillator, and a laser welding head having a condensing portion that condenses the laser light oscillated by the laser oscillator and irradiates the surface to be welded of the underwater structure. An underwater repair welding apparatus comprising a nozzle positioned at a tip of the laser welding head for supplying a shielding gas coaxially with the laser beam to a welded portion and repairing an underwater structure by laser welding underwater, It is set as the structure which installed the gas shield body of 1 or 2 in the said nozzle.

  In the gas shield body according to the present invention, the shield body body having a large number of gas holding spaces includes a nylon sponge, a bundle of fine stainless steel nets, or a flexible nylon porous body. The material is not particularly limited as long as it has a large number of minute spaces for holding gas (bubbles), absorbs irregularities and does not lose its shape.

  Further, in the gas shield body according to the present invention, as a floating suppression means for suppressing floating of the shield body in water, for example, a case that houses (encloses) the shield body, or a weight that can be installed in the shield body. In addition to being able to be adopted, the weight of the shield body itself may be increased.

  Furthermore, in the gas shield body according to the present invention, the shape of the shield body main body is preferably a rectangular parallelepiped shape in consideration of ease of manufacturing, but may be a cylindrical shape or a truncated cone shape, for example. It is.

On the other hand, in the underwater repair welding apparatus according to the present invention, a YAG laser or a fiber laser can be used for laser welding, and a semiconductor laser or a disk laser can be used.
At this time, when the laser output is 0.8 to 4.0 kW, the beam diameter of the laser light is preferably 0.6 to 1.0 mm in order to prevent excessive heat input and insufficient heat input.

  In addition, the underwater repair welding apparatus according to the present invention can be applied to any posture of a downward posture and a lateral posture, that is, the repaired and welded surface is an underwater structure when the welded surface is a bottom surface of an underwater structure. It can be applied to any repair in the case of a wall surface of an object.

  In the gas shield body and the underwater repair welding apparatus according to the present invention, when repairing the underwater structure, the contact surface of the shield body is brought into contact with the welded surface while supplying the shield gas to the gas shield body through the nozzle. When sliding, the shield gas supplied to the through hole of the shield body main body eliminates water in the welded portion, and a local dry environment in the welded portion or in the vicinity thereof is secured.

At this time, a part of the shield gas supplied to the through hole of the shield body in the gas shield body through the nozzle is formed as fine bubbles and held in a large number of gas holding spaces of the shield body, and the shield Since the contact surface of the body main body absorbs unevenness on the surface to be welded, even if there is unevenness on the surface to be welded, the shielding gas from between the contact surface of the shield body main body and the surface to be welded without but as you ejected once, as a result, the welding portion or the vicinity thereof so that the become be kept in a dry atmosphere, may perform better underwater repair welding.

  Since the gas shield body according to claim 1 of the present invention has the above-described configuration, when performing underwater repair welding, the welded portion or the vicinity thereof is brought into a dry atmosphere regardless of whether the welded surface is smooth or not. It has a very good effect that it can be maintained.

  Moreover, since the gas shield body according to claim 2 of the present invention has the above-described configuration, the shield body main body can be prevented from floating in water.

  On the other hand, since the underwater repair welding apparatus according to claim 3 of the present invention has the above-described configuration, the welded portion or its vicinity can be maintained in a dry atmosphere, and as a result, good underwater repair welding can be performed. become.

It is composition explanatory drawing which shows the gas shield body by one Example of this invention, and an underwater repair welding apparatus. It is the expanded bottom explanatory drawing (a) and enlarged sectional explanatory drawing (b) of the gas shield body in FIG.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 shows an underwater repair welding apparatus according to an embodiment of the present invention. As shown in FIG. 1, this underwater repair welding apparatus 1 is oscillated by a YAG laser oscillator 2 and a YAG laser oscillator 2. The optical fiber 3 that is the optical path of the laser light L, and a condensing unit that incorporates a condensing lens 4 that condenses the laser light L transmitted through the optical fiber 3 to an appropriate size and irradiates the underwater structure S 5 and a nozzle 6 which is arranged coaxially with the laser beam L and supplies an inert shielding gas G such as argon gas, helium gas or nitrogen gas for preventing oxidation to the welded portion. The laser welding head 7 is comprised by these.

The underwater repair welding apparatus 1 also includes a gas shield body 10 installed at the tip portion of the nozzle 6 of the laser welding head 7.
The gas shield body 10 includes a rectangular parallelepiped shield body body 12 surrounded and held by a case 11 serving as a floating prevention means. As shown in FIG. 2, the shield body 12 has a large number of gas holding spaces 13, and comes into contact with the surface to be welded (covering plate 20 described later in this embodiment) to provide irregularities on the surface to be welded. And a through-hole 15 in which the tip of the nozzle 6 is fitted to one end and the other end opens at the contact surface 14.

  When repairing the underwater structure S using the underwater repair welding apparatus 1 having such a configuration, for example, the same material as the underwater structure S (for example, SUS material) and a plate thickness of 0.5 to 4 mm is used. A rectangular covering plate 20 made of a thin plate covers the bottom surface Sa including the defective portion X generated in the underwater structure S.

  Next, while supplying the shielding gas G from the nozzle 6 of the laser welding head 7 at a flow rate of 15 to 30 (l / min) at the position entering the center side from the peripheral edge of the cover plate 20, the defective portion X of the bottom surface Sa is removed. The laser beam L is irradiated so as to surround it in a cross-beam shape.

  Specifically, the laser beam L having a beam diameter of 0.6 to 1.0 (mm) and a laser output of 0.8 to 4.0 (kW) is irradiated while being irradiated at a welding speed of 1 to 2 (m / min). When welding is performed, the thin covering plate 10 which is also a filler material is fixed to the bottom surface Sa of the underwater structure S without using a filler wire, and the necessary thickness of the welded portion is not required even when a multi-layer is formed. Can be secured.

  During the laser welding described above, when the shield gas G is supplied to the gas shield body 10 via the nozzle 6 and the contact surface 14 of the shield body 12 is brought into contact with the cover plate 20 and is slid, the shield body 12 The water in the welded portion is eliminated by the shielding gas G supplied to the through-hole 15, and a local dry environment in the welded portion or in the vicinity thereof is secured.

  At this time, a part of the shield gas G supplied to the through hole 15 of the shield body 12 in the gas shield body 10 through the nozzle 6 becomes fine bubbles and enters a large number of gas holding spaces 13 of the shield body 12. In addition, since the contact surface 14 of the shield body 12 absorbs irregularities on the cover plate 20 even if the cover plate 20 has irregularities, the contact surface of the shield body main body 12 is retained. As a result, the shield gas G does not blow out from between the cover plate 20 and the cover plate 20 at a stretch, and as a result, the welded portion or the vicinity thereof is maintained in a dry atmosphere, and good underwater repair welding can be performed. It will be.

  In the underwater repair welding method according to the above-described embodiment, the case where a YAG laser is used for laser welding has been shown. However, the present invention is not limited to this, and a fiber laser or a semiconductor laser can be used, and a disk laser is used. be able to.

  Moreover, in the above-mentioned Example, the condition which applied the underwater repair welding method concerning this invention to the repair in a downward attitude | position, ie, the repair in case the to-be-welded surface is the coating | coated board 20 on the underwater structure S, is shown. However, the present invention is not limited to this, and can also be applied to a lateral orientation, that is, repair when the welded surface is a wall surface of an underwater structure.

  Furthermore, in the above-described embodiment, the beam diameter of the laser beam L is 0.6 to 1.0 (mm), the laser output is 0.8 to 4.0 (kW), and the welding speed by irradiation with the laser beam L is 1. Although the flow rate of the inert shielding gas G is defined as 15 to 30 (l / min), it is not limited thereto.

  The configurations of the gas shield body and the underwater repair welding apparatus according to the present invention are not limited to the configurations of the above-described embodiments.

DESCRIPTION OF SYMBOLS 1 Underwater repair welding apparatus 2 Laser oscillator 5 Condensing part 6 Nozzle 7 Laser welding head 10 Gas shield body 11 Case (floating suppression means)
12 Shield body 13 Gas holding space 14 Contact surface 15 Through hole 20 Cover plate (surface to be welded)
G Inert shielding gas L Laser light S Underwater structure

Claims (3)

A gas shield body that keeps the welded part on the surface to be welded or its vicinity in a dry atmosphere when repairing the underwater structure by laser welding,
A shield body having a large number of gas holding spaces is provided.
The shield body is supplied with a shielding gas coaxially with a contact surface that contacts the welded surface and slides so as to absorb unevenness on the welded surface, and a laser beam irradiated to the welded portion. A gas shield body comprising: a through-hole having at least a tip of a nozzle fitted on one end side and having the other end opened on the contact surface.   The gas shield body according to claim 1, further comprising a floating prevention unit that suppresses floating of the shield body in water. A laser welding head having a laser oscillator, a laser welding head for condensing the laser light oscillated by the laser oscillator and irradiating the surface to be welded of the underwater structure, and the laser positioned at the tip of the laser welding head An underwater repair welding apparatus for repairing an underwater structure underwater by laser welding, including a nozzle for supplying a shielding gas coaxially with the light to a welding portion,
An underwater repair welding apparatus, wherein the gas shield body according to claim 1 or 2 is installed in the nozzle.

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