Laser welding apparatus for support grid

Abstract

The present invention relates to a laser welding apparatus for a support grid, having a manifold for effectively discharging fumes generated in a welding chamber during a welding process for the support grid, the laser welding apparatus of a support grid comprising: a base frame (100) in which a chamber mounting opening is penetratively formed, and in which a guide rail (110) is installed along the chamber mounting opening; a welding chamber (200) which is guided by the guide rail (110) and assembled with the base frame (100), and in which an openable and closable door is provided at the front, and a glass window is provided on an upper part thereof, thereby achieving airtightness; a manifold (220) which is provided on a side surface of the welding chamber (200) to discharge gas or fumes from the welding chamber (200); and a laser welding unit (300) which is installed on the base frame (100) to emit a laser through the glass window for welding the support grid seated in the welding chamber (200), wherein the manifold (220) is a tubular structure having a circular cross-section, and includes a main flow path (221) and a plurality of branch flow paths (222, 223, 224) branched in a streamlined manner on the same plane as the main flow path (221).

Description

Laser welding device for support grid

[0001] The present invention relates to a laser welding device for a support grid, and more particularly, to a laser welding device for a support grid equipped with a manifold for effectively discharging fume generated within a chamber during a welding process.

[0002] A nuclear reactor is a device that is designed to artificially control the chain fission reaction of fissile material to generate heat, produce radioactive isotopes and plutonium, or form a radiation field.

[0003] Light-water reactors typically use enriched uranium with a uranium-235 content of 2-5%. To process the uranium into nuclear fuel for use in reactors, the fuel is molded into cylindrical pellets weighing approximately 5 grams. These pellets are then loaded into Zircaloy cladding tubes, filled with springs and helium gas, and welded with end caps to create fuel rods. These fuel rods are then loaded into a skeleton to form the final nuclear fuel assembly, which combusts through a nuclear reaction within the reactor.

[0004] The support grid within the nuclear fuel assembly, along with the fuel rods, instrumentation tubes, and guide tubes, constitutes a skeleton, and is formed by dozens of support grid plates. Each support grid plate has several slot-like cutouts. These support grid plates are positioned at regular intervals in the longitudinal and transverse directions so that they intersect each other. When these support grid plates are interlocked with each other, the cutouts form a support grid with a lattice space.

[0005] However, even when the support grid plates are inserted into the cuts and fastened in this way, there is still a lot of play in the cuts, which causes the grid itself to shake. Therefore, the shaking of the support grid is eliminated by welding the intersections between the support grid plates and the areas where fixed connections are not made, such as the exterior and corners. Laser welding is the most commonly used welding method for support grids.

[0006] For example, the applicant's Korean Patent Publication No. 10-1679606 (publication date: November 28, 2016) proposes a laser welding device for a nuclear fuel assembly support grid that can improve workability and productivity and maintainability.

[0007] The inventor of the present invention seeks to further improve the laser welding device for the conventional nuclear fuel assembly support grid.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] (Patent Document 1) Korean Patent Publication No. 10-1679606 (Publication Date: November 28, 2016)

[0011] The present invention aims to provide a laser welding device having a grid support equipped with a manifold capable of effectively discharging fume generated within a chamber during a welding process.

[0012] In order to achieve the above object, the present invention provides a laser welding device for a grid, comprising: a base frame having a chamber installation opening formed therethrough and a guide rail installed along the chamber installation opening; a welding chamber guided by the guide rail and assembled with the base frame, the welding chamber having an openable door provided at the front and a glass window provided at the top to ensure airtightness; a manifold provided at a side of the welding chamber to discharge gas or dust within the welding chamber; and a laser welding unit installed in the base frame to irradiate a laser through the glass window to weld the grid installed within the welding chamber, wherein the manifold is a tubular shape having a circular cross-section, and includes a main channel and a plurality of branch channels branching out in a streamlined manner on the same plane as the main channel.

[0013] Preferably, the branch flow path includes a first branch flow path arranged on the same axis as the main flow path; and a second branch flow path and a third branch flow path arranged symmetrically left and right about the first branch flow path.

[0014] More preferably, the second branch element comprises a first branch element extending at an acute angle (<90°) with the main branch element, and a second branch element extending from the first branch element such that the open end is positioned opposite the open end of the main branch element.

[0015] More preferably, each opening of the first quarter euro to the third quarter euro is arranged on the same plane.

[0016] A laser welding device for a support grid according to the present invention comprises: a base frame having a chamber installation opening formed therethrough and a guide rail installed along the chamber installation opening; a welding chamber guided by the guide rail and assembled with the base frame, the welding chamber having an openable door provided at the front and a glass window provided at the top to ensure airtightness; a manifold provided at a side of the welding chamber to discharge gas or dust within the welding chamber; and a laser welding unit installed in the base frame to irradiate a laser through the glass window and weld the support grid installed within the welding chamber, wherein the manifold is a tubular shape having a circular cross-section, and includes a main channel and a plurality of branch channels branching out in a streamlined manner on the same plane as the main channel, thereby having the effect of preventing zirconium dust generated in the welding chamber during the welding of the support grid from accumulating within the manifold and accumulating on the surface.

[0017] Fig. 1 is a side view of a laser welding device for a support grid according to an embodiment of the present invention.

[0018] FIG. 2 is a perspective view showing a welding chamber of a laser welding device for a support grid according to an embodiment of the present invention.

[0019] Figures 3 (a) and (b) are a perspective view and a cross-sectional view of a manifold according to an embodiment of the present invention, respectively.

[0020] Figure 4 is a plan view of a manifold according to each embodiment of the present invention.

[0021] Figures 5 (a) and (b) are a perspective view and a cross-sectional view of the manifold used as a comparative example, respectively.

[0022] Figures 6 (a) and (b) are perspective views showing the shape of a manifold used as an embodiment of the present invention and a comparative example, respectively.

[0023] Figures 7 (a) and (b) are data showing the results of 3D surface plot (2D streamline velocity) analysis for examples and comparative examples of the present invention, respectively.

[0024] Figures 8 (a) and (b) are data showing the results of 3D flow trajectory (velocity) analysis for an embodiment and a comparative example of the present invention, respectively.

[0025] Figures 9 (a) and (b) are data showing the results of velocity analysis for particles (zirconium) for examples and comparative examples of the present invention, respectively.

[0026] The specific structural and functional descriptions presented in the embodiments of the present invention are merely illustrative for the purpose of explaining embodiments according to the concept of the present invention, and embodiments according to the concept of the present invention may be implemented in various forms. Furthermore, they should not be construed as being limited to the embodiments described herein, but should be understood to include all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention.

[0027] Meanwhile, the terminology used in this specification is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. It should be understood that the terms "comprises" or "has" in this specification are intended to specify the presence of implemented features, numbers, steps, operations, components, parts, or combinations thereof, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0029] Referring to FIG. 1, the laser welding device of the support grid of the present invention (hereinafter, abbreviated as “welding device”) includes a base frame (100), a welding chamber (200) that is detachably assembled to the base frame (100) and in which laser welding of the support grid is performed, a laser welding unit (300) that irradiates a laser into the welding chamber (200) to perform welding of the support grid, and a locking member (400) for fixing the welding chamber (200) to the base frame (100).

[0030] The base frame (100) is where the main devices are installed, and a laser welding part (300) is installed at the top, and a chamber installation hole for mounting a welding chamber (200) is formed horizontally through the center. A guide rail (110) is provided along the chamber installation hole, so that installation or removal of the welding chamber (200) can be performed by being guided by the guide rail (110). The locking member (400) functions to secure the welding chamber (200) located on the base frame (100).

[0031] The welding chamber (200) has a body structure that can be sealed inside with a door that can be opened and closed at the front and a glass window at the top.

[0032] In this welding chamber (200), argon is injected in a vacuum state before welding, and welding of the support grid is performed, and dust generated during the welding process is discharged to the outside through a manifold installed in the welding chamber (200).

[0033] FIG. 2 is a perspective view showing a welding chamber of a laser welding device of a support grid according to an embodiment of the present invention, and FIGS. 3 (a) and 3 (b) are a perspective view and a cross-sectional view, respectively, of a manifold according to an embodiment of the present invention.

[0034] Referring to FIGS. 2 and 3, a welding chamber (200) is provided with a first opening (201) in which a door is installed at the front, a second opening (202) in which a glass window is installed at the top, and a welding table (210) is installed inside where a support grid, which is a target for welding, is positioned. The support grid is assembled with a separate welding fixture and fixed to the welding table (210) to perform laser welding.

[0035] As described above, the welding chamber (200) is equipped with a manifold (220) for discharging dust generated during the welding process to the outside, and a pipe flange (203) to which the manifold (220) is connected may be provided on the side of the welding chamber (200).

[0036] A manifold (220) according to an embodiment of the present invention is tubular with a circular cross-section and includes a main flow path (221) and a plurality of branch flow paths (222)(223)(224) that branch out in a streamlined manner on the same plane as the main flow path (221).

[0037] Figure 4 is a plan view of a manifold according to each embodiment of the present invention.

[0038] Specifically, referring to FIG. 4, the branch flow paths (222)(223)(224) include a first branch flow path (222) arranged on the same axis (C1) as the main flow path (221), and a second branch flow path (223) and a third branch flow path (224) arranged symmetrically left and right with the first branch flow path (222) as the center. Meanwhile, in the present embodiment, the branch flow paths (222)(223)(224) are configured as a pair on the left and right with the first branch flow path (222) as the center, for a total of three, but it should be understood that the same can be expanded to two or more pairs of branch flow paths centered on the first branch flow path.

[0039] Preferably, the second branch flow path (223) includes a first branch element (223a) extending at an acute angle (θ<90°) with the main flow path (222), and a second branch element (223b) extending from the first branch element (223a) but having an open end (223') positioned opposite to the open end (221') of the main flow path (222). Meanwhile, in FIG. 4, reference numeral D shows a schematic center line of the first branch element (223a), C2 represents an axis orthogonal to the central axis C1, and S1 represents an arbitrary plane orthogonal to the plane defined by C1 and C2 and parallel to C2.

[0040] In this way, the second branch flow path (223) is branched from the first branch element (223a) at an angle of less than 90° with the main flow path (222), and the center of the first branch element (223a) itself may be a curve rather than a straight line, and the connection portion between the first branch element (223a) and the second branch element (223b) has a streamlined curved surface. Meanwhile, the third branch flow path (224) also has the same shape as the second branch flow path (223) and is symmetrical on both sides as described above.

[0041] Preferably, each opening (222')(223')(224') of the first quarter euro (222) to the third quarter euro (224) is arranged on the same plane (S1).

[0042] The manifold (220) configured in this manner can prevent zirconium dust generated during the welding process of the support grid in the welding chamber from accumulating on the surface by accumulating on the flow path.

[0043] Below, the results of a flow analysis performed on a manifold, which is a key component of the present invention, are shown, and a manifold used as a comparative example for comparison with the manifold of the present invention is shown in Fig. 5.

[0044] (a)(b) of Fig. 5 are a perspective view and a cross-sectional view of a manifold of a comparative example, respectively. The manifold (10) used as a comparative example includes a main body (11) having a space inside a square shape with a rectangular cross-section, an inlet pipe (12) provided at the center of one side of the main body (11), a first outlet pipe (13) provided at the main body (11) on the opposite side of the inlet pipe (12), and a pair of second outlet pipes (14) provided symmetrically left and right about the first outlet pipe (13).

[0045] Figures 6 (a) and (b) are perspective views showing the shape of a manifold used as an embodiment of the present invention and a comparative example, respectively.

[0046] Next, (a)(b) of FIG. 7 are data showing the results of 3D surface plot (2D streamline velocity) analysis for the examples and comparative examples of the present invention, respectively, and (a)(b) of FIG. 8 are data showing the results of 3D flow trajectory (velocity) analysis for the examples and comparative examples of the present invention, respectively.

[0047] In FIGS. 7 and 8, it can be seen that the present invention has less vortex in the branch flow paths on both sides, whereas in the comparative example, the vortex appears severely on the second outlet pipe side on both sides.

[0048] Figures 9 (a) and (b) are data showing the results of velocity analysis for particles (zirconium) for examples and comparative examples of the present invention, respectively.

[0049] As can be seen in Fig. 9, the present invention has a faster particle transport speed compared to the comparative example, so the flow rate is increased and the amount of fume discharged in the same time is large. In addition, the deviation in the flow rate is more uniform compared to the comparative example, so there is a low possibility of fume accumulating at the left and right inlets.

[0050] The following [Table 1] shows data for the case where zirconium particles of approximately 0.1 to 0.2 ㎛ in size are assumed to be introduced at 200 points from three inlets.

[0051] Comparative Example Number of particles of this invention (total) 86148 Number of particles 0.1 micron 2672 Number of particles 0.2 micron 6076 Mass accumulation rate (total) 0.0009 kg / s 0.0015 kg / s Mass accumulation rate 0.1 micron 0.0006 kg / s 0.0008 kg / s Mass accumulation rate 0.2 micron 0.0003 kg / s 0.0007 kg / s

[0052] Looking at [Table 1] together with Fig. 9, it can be confirmed that when the same number of fume particles is introduced, about 70% more fume particles are discharged from the outlet compared to the existing one, and this pattern is the same regardless of the size of the particles. In addition, it can be confirmed that the amount of accumulated fume particles is improved by about 66% compared to the existing one as the particle transport speed increases and the flow rate deviation between the inlets is evenly improved. Through this, the manifold of the present invention can significantly improve the accumulation of explosive zirconium fume, improve worker safety by preventing internal explosion through friction between fumes, and reduce the probability of combustion products entering the welding chamber, thereby improving the quality of the support grid.

[0053] The present invention described above is not limited to the above-described embodiments and the attached drawings, and it will be apparent to a person skilled in the art to which the present invention pertains that various substitutions, modifications, and changes are possible within a scope that does not depart from the technical spirit of the present invention.

[0054] [Explanation of symbols]

[0055] 100: Base frame 110; Guide rail

[0056] 200: Welding chamber 220: Manifold

[0057] 221: Main Euro 222: First Quarter Euro

[0058] 223: Euro 2nd Quarter 224: Euro 3rd Quarter

[0059] 300: Laser welding

Claims

1. A base frame having a chamber installation hole formed through it and a guide rail installed along the chamber installation hole; A welding chamber guided by the above guide rail and assembled with the above base frame, having an openable door provided at the front and a glass window provided at the top to ensure airtightness; A manifold provided on the side of the above welding chamber to discharge gas or dust within the welding chamber; It includes a laser welding unit installed on the above base frame and irradiating a laser through the glass window to weld a support grid positioned in the welding chamber. The above manifold is a tubular shape having a circular cross-section, and is a laser welding device of a support grid including a main flow path and a plurality of branch flow paths branching out in a streamlined manner on the same plane as the main flow path.

2. In paragraph 1, the branch euro is, A first quarter euro arranged on the same axis as the above main euro; A laser welding device for a support grid including second-quarter and third-quarter euros arranged symmetrically left and right with the first-quarter euro as the center.

3. In the second paragraph, a laser welding device for a support grid including a first branch element extending at a certain angle from the main branch element, and a second branch element extending from the first branch element so that the open end is positioned opposite to the open end of the main branch element.

4. A laser welding device for a support grid, characterized in that, in the third paragraph, each opening end of the first branch flow path to the third branch flow path is arranged on the same plane.

5. A manifold for a welding chamber that is installed in the welding chamber and allows gas or dust to be discharged. The above manifold is a tubular manifold having a circular cross-section, and is a manifold for a welding chamber including a main flow path and a plurality of branch flow paths branching out in a streamlined manner on the same plane as the main flow path.

6. In paragraph 5, the branch euro is, A first quarter euro arranged on the same axis as the above main euro; A manifold for a welding chamber including a second-quarter flow path and a third-quarter flow path arranged symmetrically left and right with the first-quarter flow path as the center.

7. A manifold for a welding chamber, wherein the second branch element in the sixth paragraph includes a first branch element extending at an acute angle (<90°) with the main branch element, and a second branch element extending from the first branch element so that the open end is positioned opposite the open end of the main branch element.

8. A manifold for a welding chamber, characterized in that, in the 7th paragraph, each opening of the first branch flow path to the third branch flow path is arranged on the same plane.

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