JPS6253274B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing pulsed heat sink panels used in oil-filled electrical equipment.

BACKGROUND OF THE INVENTION Oil-immersed transformers are provided with a panel-type radiator as the most common cooling device to cool the heat generated during operation. This panel-type heatsink is constructed by providing a large number of heatsink panels, and the heatsink panel has several long grooves 2 on the flat surface of a thin metal plate 1, as shown in FIGS. 9 and 10. Convex flange portions 6 formed in parallel and having holes 5 on the top and bottom are squeezed out and formed by pressing, and two thin metal plates 1 are formed into two long groove portions 2, respectively.
After the convex flange portions 6 are stacked so as to face each other, and the long groove portions 2 are fixed by spot welding or seam welding, the peripheral edge portion 4 is similarly fixed by welding. This welding of the peripheral edge 4 is performed by so-called seam welding, in which the peripheral edge 4 is continuously welded with a pair of roll electrodes sandwiching the peripheral edge 4. A heatsink is formed by stacking and assembling the thus-formed heatsink panels 7 in a required number according to the heat radiation amount of the transformer.

However, the peripheral edge 4 of this heatsink panel 7
When the seam welding is performed, as shown in FIG. 11, the seam welded portion 8 undergoes heat shrinkage after welding, so that the peripheral edge 4 is corrugated and a gap is formed with respect to the outside. For example, when the transformer is used outdoors, this void allows rainwater to enter and promotes so-called crevice corrosion, which is undesirable from the standpoint of long-term reliability of the transformer. In order to minimize such voids, a large amount of water is injected into the seam welding area during seam welding to suppress distortion caused by heat shrinkage, and the seam is passed through a straightening roller in the next process. However, it is difficult to completely eliminate voids.

In addition, in order to eliminate any voids, it is possible to construct the seam weld 8 at the outermost part of the peripheral edge 4, but semi-molten metal due to energized heat may fly out to the outside, causing defects inside the weld. There are disadvantages such as the roller electrode of the seam welding device coming off from the peripheral edge 4 or the roller electrode being damaged.

Furthermore, as another method, the end surface of the peripheral portion 4 may be
MAG welding, or TIG, uses a stable arc of argon and carbon dioxide gas mixture.
It is also possible to join by welding or plasma arc welding. In this case, regardless of whether the welding position is downward, horizontal, or vertical, the throat thickness P ₁ of the weld metal cannot be made larger than the thickness t of the thin metal plate 1 once, as shown in Fig. 12. This is not possible with just welding. That is, molten metal drips during welding regardless of the welding method. In addition, in order to prevent such dripping of molten metal, when the edges of the peripheral edge 4 are welded from both sides of the peripheral edge 4 of the thin metal plate 1 with caulking plates such as copper plates, molten metal may be interposed between the caulking plates. It is conceivable to support the molten metal by holding the metal in place, but it is impossible to weld such deep parts because the arc may move to the copper plate of the backing plate, making the welding unstable. Therefore, even with arc welding such as MAG, TIG, and plasma welding, the weld throat thickness P ₁
It is inevitable that the thickness t of the thin metal plate 1 becomes smaller than the thickness t of the thin metal plate 1 serving as the base material. Internal pressure fluctuations during operation of the transformer generate repeated stress on the end of the peripheral portion 4, so the small throat thickness as described above cannot withstand internal pressure fluctuations, and the reliability of mechanical strength is correspondingly low. it is conceivable that.

Regarding welding speed, the MAG welding method
Although it is faster than TIG and plasma arc welding, the higher the speed, the more it is affected by the oil and fat deposited on the surface of the part to be welded, resulting in partial non-weld areas. It is necessary to strictly remove fats and oils. In addition, with TIG and plasma arc welding, if the speed is increased, the molten metal does not have enough time to release bubbles and solidifies, so it is affected by the degree of deoxidation of the base material, such as rimmed steel, which has a poor deoxidation degree. In the case of materials, there is a drawback that bubbles are easily generated.

As mentioned above, even with various conventional welding methods, it is difficult to completely eliminate the gap in the peripheral edge 4.
In addition, the end face of the peripheral portion 4 is welded to reduce the throat thickness P ₁ to the plate thickness t.
It was difficult to make the film thicker, and there were issues that needed to be improved, such as the need to increase the number of pretreatment steps and to select materials.

A first object of the present invention is to provide a highly reliable method of manufacturing a heat sink panel that has excellent mechanical strength and is resistant to corrosion outdoors.

The second objective is a method for manufacturing a radiator panel that has excellent mechanical strength, prevents the generation of bubbles in the welded area through a mixed metallurgical reaction of deoxidizing elements, and further improves the welding speed. Our goal is to provide the following.

Means and operation for solving the structural problems of the invention The first invention is to overlap two thin metal plates formed in a predetermined shape with each other, and to create an upper mold and a lower mold of approximately the same size as the thin metal plates. The two stacked metal thin plates are sandwiched between the molds and supported under pressure, and the peripheral end faces of the two stacked metal thin plates are melted by laser welding to form a thick throat. Accordingly, the present invention is characterized by providing a method for manufacturing a highly reliable heat sink panel that has excellent mechanical strength and is durable against corrosion outdoors.

Moreover, the second invention is a second invention formed into a predetermined shape.
A metal sheet formed by blending an oxygen scavenging element is sandwiched between two metal thin plates, and the metal sheets are stacked on top of each other. Mechanical strength is achieved by sandwiching two thin metal plates and supporting them under pressure, and by laser welding the end faces of the peripheral edges of the two stacked metal thin plates and metal sheets to form a thick throat. The present invention is characterized by providing a method for manufacturing a radiator panel that has excellent properties, prevents the generation of bubbles in the welded area due to a mixed metallurgical reaction of deoxidizing elements, and further improves the welding speed using laser light.

Embodiment Hereinafter, the first invention will be described with reference to an embodiment shown in FIGS. 1 to 7, in which the same parts as in FIGS. 9 to 12 are given the same reference numerals. In FIG. 2, the welding device for the heat sink consists of a laser welding device 11 and a unit holding device 12. The laser welding device 11 includes a laser oscillator 15 installed on a running section 13 that runs on a rail 13a installed perpendicular to the direction of the laser beam, and an optical axis system section 16 for the laser beam on the laser oscillator 15. and a focus unit 17 are attached. Optical axis system part 1
6 is an X-axis section 1 that can be expanded and contracted in the direction in which the laser beam travels.
8, a mirror unit 19 connected to the X-axis portion 18 and converting the traveling direction of the laser beam by 90 degrees;
The X-axis portion 1 is connected to this mirror unit 19.
8 and the direction of the rail 13a (Y-axis direction), the Z-axis section 20 is extendable and retractable in a direction converted by an angle of 90 degrees, and is connected to this Z-axis section 20 to direct the laser beam to the X-axis section 18. A mirror unit 21 that changes the angle by 90 degrees in the direction, and a focus unit 17 that is connected to this mirror unit 21 and focuses the laser beam.
It is composed of. With this configuration, the laser beam generated from the laser oscillator 15 passes through the optical axis system section 16 and is emitted from the focus unit 17. It can be freely moved in the axial and Z-axis directions.

On the other hand, the unit holding device 12 has an upper mold 23 and a lower mold 24 for sandwiching and pressing the peripheral edge 4 of the radiator panel 7, and is equipped with a guide (not shown) to prevent the relative positions of the two from shifting. ing. The upper mold 23 is attached to an operating device 25 that operates or presses it up and down, and the lower mold 24 is connected to the upper mold 2.
The radiator panel 7 is sandwiched between the upper mold 23 and the lower mold 24, and is connected to a rotating device 26 that can rotate the upper mold 23 and the lower mold 24 by an angle of 90 degrees around their central axes. The rotating device 26 includes a mechanism section 26a provided below the lower die 24, and a drive section 26b connected to the mechanism section 26a. Also,
The upper mold 23 and the lower mold 24 have projections and depressions formed to match the projections and depressions of the radiator panel 7.
It is formed in such a shape that only the peripheral edge 4 of the holder is pressed. The dimensions of the upper mold 23 and the lower mold 24 are formed to be approximately the same as the dimensions of the radiator panel 7. Alternatively, as shown in FIG. 1, a patch plate 32 made of, for example, a copper member can be applied.

Next, a method for manufacturing a radiator panel using this apparatus will be described. As shown in FIG. 3, the thin metal plate 1 has several long grooves 2, a convex flange 6 with holes 5 formed above and below it, a reinforcing recess 31 for reinforcing the flange 6, etc. This kind of thin metal sheet 1 is formed by press working.
The radiator panel 7 is constructed by overlapping two sheets with their respective long grooves 2 and reinforcing recesses 31, spot welding or seam welding the long grooves 2, and fixing the reinforcing recesses 31 by spot welding. do.

Peripheral edge 4 of the radiator panel 7 formed in this way
As shown in FIG. 2, between the upper die 23 and the lower die 24 of the unit holding device 12, the unevenness of the radiator panel 7 is matched with the unevenness formed on the upper die 23 and the lower die 24. After positioning and pinching, the upper mold 23 is pressed by operating the operating device 25 to press and support the peripheral edge part 4.

Then, the pre-excited laser oscillator 15 is
The X-axis section 18 and the Z-axis section 20 are moved in the axial direction.
are moved and adjusted in the X-axis direction and the Z-axis direction, respectively, and as shown in FIG. Next, the position of the laser beam emitted from the focus unit 17 is determined. Thereafter, the laser beam shutter (not shown) is operated to irradiate the end face 33 with the laser beam, and the laser oscillator 15 is run again in the welding direction of the Y axis, that is, along the rail 13a, as shown in FIG. and weld.
When such welding operation progresses to the end of one side of the heat sink panel 7, the laser beam is shielded, the focus unit 17 is returned to its origin, and at the same time, the heat is radiated by the upper die 23 and the lower die 24. While pressing and holding the container panel 7, it is rotated through an angle of 90 degrees by the rotating device 26. Thereafter, in the same manner as described above, the laser beam is positioned at the welding start point of the end face 33 of the peripheral edge 4 of the new side to be welded, and the laser oscillator 1 is turned on while irradiating the laser beam by operating the laser beam shutter.
5 is run, and the welding operation of the end face 33 is performed. After welding of the end faces 33 on the four sides is completed using the laser beam in this manner, the operating device 25 is operated to weld the upper mold 23.
, and take out the radiator panel 7.

As shown in FIG. 4, the radiator panels 7 having their end faces 33 welded in this manner are stacked in a set number to form a radiator. First, the inner peripheral part 34 adjacent to the hole 5 of the flange part 6 of the radiator panel 7 is
They are sequentially welded and joined from hole 5 by stitch welding or TIG welding. Next, connecting pipes 35 and 36 are welded to the upper and lower flange portions 6 of the final end, respectively.
The first hole 5 is covered by welding blind plates 37 and 38, respectively. In addition, an auxiliary member 39 is attached by welding to reinforce each heatsink panel 7, and the heatsink 4
0 is configured. This heat sink 40 is attached to, for example, a transformer 41 as shown in FIG.

Next, the effects of the first invention will be explained. Laser welding has a thermal energy density that is one order of magnitude higher than TIG welding or plasma arc welding, so welding with this laser light
As shown in FIG. 7 and FIG. 7, the throat thickness welded portion 42 of the end face 33 has deep penetration, and the throat thickness P ₂ can be increased. In addition, the throat thickness _P2 can be freely changed by adjusting the focus of the laser beam, so the throat thickness can be made sufficiently larger than the thickness t of the thin metal plate 1.
Can be _P2 . If you want to make the throat thickness particularly large, use the upper mold 23 and lower mold 24 in Fig. 1.
If the end surfaces 33 are arranged inwardly, that is, retracted, from the end surfaces 32a of the two backing plates 32 sandwiched between the two backing plates 32, the metal of the thin metal plate 1 melted by the excessive thermal energy of the laser beam will be held between the two backing plates 32. Since it can be held between the plates 32, welding with a large throat thickness can be performed.

In this way, a welded portion with a sufficient throat thickness is formed on the end face 33, so that corrosion from the end face due to outdoor rainwater or dirt can be prevented. Furthermore, since the mechanical strength is increased against internal pressure fluctuations in the radiator, damage caused by repeated stress can be prevented.

Next, an embodiment of the second invention will be described with reference to FIG. 8, in which the same parts as in FIG. 1 are given the same reference numerals.
An extremely thin metal sheet 43 formed by blending an oxygen scavenging element is sandwiched between two thin metal plates 1, and the end surface 33 is sandwiched between two thin metal plates 1.
are aligned, and the pressing plate 32 is pressed by the upper mold 23 and the lower mold 24. This metal sheet 43
It is formed by blending oxygen scavenging elements such as Si, Mn, and Al. Similarly to the above, when this end face 33 is laser welded, the thin metal plate 1 and the metal sheet 43 are melted, and the deoxidizing elements of the metal sheet 43 undergo a mixed metallurgy reaction, converting oxygen in the molten metal into MnO, SiO ₂ ,
Since it is fixed in the form of Al ₂ O ₃ and the like and suppresses the generation of CO gas, it is possible to prevent the generation of bubbles in the welded area. Therefore, there is an advantage that even if the welding speed using laser light is increased, welding can be performed without generating bubbles.

Effects of the Invention As explained below, according to the first invention, two molded thin metal plates are stacked on top of each other and sandwiched between an upper mold and a lower mold, and the end surfaces are laser welded. By performing welding with a thick throat, it is possible to prevent corrosion from the end face and provide a reliable method for manufacturing a heat sink panel with increased mechanical strength.

Further, according to the second invention, a metal sheet formed by blending an oxygen scavenging element is sandwiched between two molded thin metal plates, and the metal sheets are stacked on top of each other and sandwiched between an upper mold and a lower mold, By forming this end face with a thick throat by laser welding, it has excellent mechanical strength, and the oxygen-removing elements prevent the generation of bubbles in the welded area through a mixed metallurgy reaction, further increasing the welding speed using laser light. A method of manufacturing a heat sink panel that can be improved can be provided.

[Brief explanation of the drawing]

FIG. 1 is a side view of a main part of laser welding showing an embodiment of the first invention, FIG. 2 is a perspective view showing a laser welding device for implementing the embodiments of the first and second inventions, and FIG. FIG. 3 is a front view showing the heat sink panels manufactured according to the embodiments of the first and second inventions, and FIG. 4 shows the assembly of the heat sink panels manufactured according to the embodiments of the first and second inventions. Partial cross-sectional side view, 5th
The figure is a perspective view showing a transformer equipped with heat sinks according to embodiments of the first and second inventions, and FIGS. 6 and 7 are peripheral edges of heat sink panels manufactured according to embodiments of the first invention, respectively. The main parts of the section are shown, and FIG. 6 is a cross-sectional view.
FIG. 7 is a perspective view, FIG. 8 is a side view showing essential parts of the embodiment of the second invention, FIGS. 9 to 12 respectively show conventional heat sink panels, and FIG. 9 is a front view. FIG. 10 is a side view, FIGS. 11 and 12 each show a main part of the peripheral edge of the radiator panel, FIG. 11 is a perspective view, and FIG. 12 is a sectional view. DESCRIPTION OF SYMBOLS 1... Metal thin plate, 4... Peripheral part, 7... Heatsink panel, 11... Laser welding device, 12... Unit holding device, 15... Laser oscillator, 16... Optical axis system part, 17
... Focus unit, 23... Upper die, 24... Lower die, 25... Operating device, 26... Rotating device, 32... Backing plate, 33... End surface, 42... Throat thickness welding part, 43...
metal sheet.

Claims (1)

[Claims] 1. Two thin metal plates molded into a predetermined shape are stacked on top of each other, and the two stacked metal plates are placed between an upper mold and a lower mold of approximately the same size as the thin metal plates. A method for manufacturing a radiator panel, which comprises forming a thick throat by melting the end faces of the peripheral edges of the two superimposed thin metal plates sandwiching the thin metal plates and supporting them under pressure by laser welding. . 2. A metal sheet formed by blending an oxygen scavenging element is sandwiched between two thin metal plates formed into a predetermined shape, and the metal sheets are stacked on top of each other to form an upper mold and a lower mold of approximately the same size as the thin metal sheets. The two stacked metal thin plates are sandwiched between the molds, and the peripheral edge surfaces of the two stacked metal thin plates and the metal sheet, which are supported under pressure, are melted by laser welding to reduce the throat thickness. A method for manufacturing a radiator panel characterized by forming it thickly. 3. The method of manufacturing a radiator panel according to claim 2, wherein the metal sheet is formed by blending oxygen-reducing elements such as Si, Mn, and Al.