JPS6037609B2 - Method for manufacturing heat dissipation containers for oil-filled electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a transformer that can suppress deformation caused by welding assembly even when using thin metal plates when forming a heat dissipation container comprising a large number of hollow fins filled with insulating oil. The present invention relates to a method of manufacturing a heat dissipation container for oil-filled electrical equipment, such as a container tank.

Electrical equipment has become smaller and lighter than before, but
Along with this, there is a demand for smaller and lighter containers for housing electrical equipment bodies, and in particular, the thickness of the metal plates constituting the containers has become extremely thin.

However, when the plate thickness becomes thinner, deformation during assembling and welding is large, causing problems in terms of appearance and functionality.In addition to constraints from external forces and the weight of the electrical equipment itself, there are also constraints from the manufacturing technology perspective, which make the plate thinner. It had its limits. Among these, heat radiating containers, such as those for transformers, require a radiator to dissipate heat generated during load, and have a structurally complex assembly and welding process, so the above restrictions are severe.

FIG. 1 is an example of a conventional oil-immersed transformer. A heat sink b having a cylindrical shape and a large number of hollow fin portions a, a is used on both sides of the heat sink, and the inside of the hollow fin portions a, a of the heat sink b is filled with insulating oil. During operation, oil circulates and radiates heat. The heat dissipation plate b is economically produced by bending a strip-shaped thin metal plate into a pulse wave shape at predetermined intervals to form a large number of fins, and welding and closing both ends of each fin in the longitudinal direction. Then, this heat sink plate b is bent into a cylindrical shape, and thin metal plate side plates c, c are welded to both ends in the width direction to form both parts of the heat sink. This welded portion is shown in Figure 2. The side plate c has a flange portion d at one end to increase the rigidity of the side plate c and to form a packing seat for sealing the tank. The wider the flange part d, the higher the rigidity, but if it is made too wide, the gap between the contents of the transformer and the inner wall of the tank will increase accordingly, which is not a good idea from the standpoint of miniaturization, and the current flange part d is The width is 10-20 legs. By the way, after the above structures are welded, a large residual tensile stress is generated at the weld bead e and the weld side edge of the side plate c due to shrinkage due to temperature drop.

This causes the side plate c to buckle and deform as shown in FIGS. 3 and 4. Needless to say, the amount of deformation is proportional to the amount of shrinkage of the weld bead and the side plate end green, and is inversely proportional to the rigidity of the side plate c. In particular, when welding thin metal plates, the amount of weld bead relative to the thickness of the plate is larger than that of thick plates, and the rigidity is conversely small, so the amount of deformation becomes significantly large. Partly because the width of the flange portion d cannot be made large, there is no means to prevent deformation. When such deformation occurs, it requires a great deal of effort to correct it, and it becomes difficult to obtain a beautiful appearance. During welding work, workers are required to be extremely careful not to melt the plate and maintain a high degree of tension, not allowing even the slightest mistake in hand movement, which naturally reduces work efficiency and productivity. descend. Automation of the welding process is conceivable, but after the heat dissipation plate is bent into a cylindrical shape and the shape of the container as 8 parts is formed to some extent, automatic tracing equipment, container rotation equipment, container movement equipment etc. are required. This requires large-scale equipment, resulting in a huge amount of investment. Considering the current situation where it has not been possible to reduce the size and weight of this type of container due to the large obstacles and inconveniences caused by making the constituent plates of the heat dissipation container thinner, the present invention has been developed to extremely minimize the amount of deformation caused by welding. The present invention provides a method for manufacturing a heat dissipation container for oil-filled electrical equipment in which welding can be easily automated.

This will be explained in detail below with reference to the figures.

First, in the first step, a strip-shaped thin metal plate is bent into a pulse wave shape at predetermined intervals to form a large number of fins, and at the same time both longitudinal ends 1', 1' are automatically closed by falling, and two Hollow fin parts 1, 1 having a gap surrounded by two plates are formed.

This is cut into a predetermined length in the undulating direction of the hollow fin portions 1, 1 to form the heat sink 2. Next, in the second step, as shown in FIG. 6, for example, the heat radiating plate 2 is placed on rollers 3, 3 so that it can be transported.

This may be a continuous step from the first step. On both sides of the heat sink 2 in the width direction, thin metal side plates 5, 5 (7th
Figure) is attached. In this case, the two green ends are butted against each other, or the side plates 5, 5 are slightly overlapped with each other as shown in the second figure, and the abutted or overlapping portions are arranged in a straight line. Next, the heat radiating plate 2 and the side plates 5, 5 are transferred while being held by holding rollers 6, 6. holding roller 6,
6, the tips of stationary automatic welding torches 8, 8 are arranged. Here, the heat dissipating plate 2 and the side plates 5, 5, which were transferred at the same time, are welded continuously by the torches 8, 8 in a straight line from their ends at their abutting or overlapping parts to form a joint plate. The side plates 5, 5 after being molten are subsequently straightened by straightening rollers 7, 7. Further ahead, the side plate 5,
The outer green end of 5 is bitten by the bending rollers 9, 9 and bent to the opposite side of the hollow fin parts 1, 1 to form a flange part 10. The notches 4, 4 are formed by this flange portion 101. Next, in the third step, the joint plate manufactured in the second step is bent outward at the positions of the notches 4, 4 to form a cylinder, and both ends are welded to form the body. form (Figure 6). 11 is the welded portion.

Furthermore, a bottom plate 12 is attached to one side of the cylindrical body produced in the third step.
The fourth step is to weld the pieces into a box.

In the above process, the flange portions 10 may be provided on the side plates 5, 5 in advance, and the side plates 5, 5 may be joined to both ends of the heat sink plate 2. As described above, the present invention provides hollow fin portions 1, 1
A heat dissipation plate 2 having
In particular, we welded a flat plate in a straight line and then bent it into a cylindrical shape, making it easier to automate welding, minimizing distortion, and allowing the use of thin metal plates. Become.

That is, the welding of the heat sink 2 and the side plates 5, 5 is performed using the holding loaf 6,
Since the welding is carried out in a restrained state, the distortion during welding is small.
Furthermore, since the deformation can be easily corrected by the correction rollers 7, 7, only a very small deformation remains compared to the conventional method, and a beautiful appearance can be obtained. Moreover, since welding can be performed in a straight line, it is easy to automate welding, and this automation improves workability and productivity without putting extreme stress on workers, and reduces the occurrence of welding defects.
Reliability and yield are significantly improved. On the other hand, when making a cylindrical joint plate and welding both ends, it requires the same skill and tension as conventional thin plate welding, but since the welding length is relatively short, there is no problem, and the welding line is simple, so automation is not possible. It's easy. As described above, according to the method of the present invention, since the heat sink and the side plate are welded while being held in a straight line and then bent, deformation due to welding can be suppressed.
Moreover, this eliminates the need for the flange to have a deformation prevention function, so the width of the flange can be set small, which allows the transformer contents to be brought closer to the inner surface of the heat sink, which saves oil and improves external appearance. Helps reduce size. Furthermore, automation of melt heating can be implemented with a significantly lower investment amount than conventional welding automation equipment, and this has the excellent effect of helping to reduce costs and contributing greatly as part of resource conservation.

[Brief explanation of drawings]

Figure 1 is a front view of the oil-immersed transformer, Figure 2 is an enlarged sectional view taken along the x-X line in Figure 1, Figure 3 is a sectional view showing a state where welding distortion has occurred in the same figure, and Figure 4. is a perspective view showing the state of welding distortion,
FIG. 5 is a perspective view showing an embodiment of the method for manufacturing a heat dissipation container according to the present invention, FIG. 6 is a perspective view of a heat dissipation container for a transformer manufactured by the same method, and FIG. 7 is the formation of the flange portion during manufacturing. It is an enlarged perspective view showing a state. 1... Hollow fin part, 2... Heat sink,
3...Roller, 4...Notch, 5...
...Side plate, 6...Holding roller, 7...
Straightening roller, 8... Automatic welding torch, 9...
End bending roller, 10... flange part, 11... welding line,
12...Bottom plate. Younger brother figure 2 figure Tsutomu 3 figure 4 younger brother figure 6 younger brother figure 7

Claims (1)

[Claims] 1 A strip-shaped thin metal plate is bent into a waveform at predetermined intervals to form a large number of fins, and both ends of each fin in the longitudinal direction are welded and closed to form a hollow fin. Manufacture of a heat dissipation container for oil-filled electrical equipment in which a cylindrical body is formed by a heat dissipation plate cut to a predetermined length and side plates made of thin metal plates fixed to both sides of the heat dissipation plate in the width direction. In the method, after the end portions of the heat dissipation plate and the side plate made of thin metal plate are aligned in a straight line butted against each other or overlapped, and while holding them by a holding device, the straight butted portion or An oil-filled electric appliance characterized in that the overlapping part is welded to form a joint plate, and then this joint plate is bent at several places at intervals with the hollow fin part outside to form a body part. Method for manufacturing a heat dissipation container.