JP2732628B2 - Transformer tank manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a corrugated transformer tank in which a metal plate forming a side wall of the tank is corrugated to form a radiation fin portion. It is about.

[Prior Art] In this type of transformer tank, a metal plate having a large number of hollow radiating fins formed by corrugating, an upper frame member and a lower frame member welded to both ends in the width direction of the metal plate. Thus, a side wall of the tank is formed, a bottom plate is attached to the lower frame, and a lid plate is attached to the upper frame, thereby forming a sealed tank.

Since such a corrugated transformer tank can have a predetermined strength by forming the side wall with a thin metal plate,
It can be made small and lightweight. In addition, this type of tank has a remarkably large side wall surface area and low oil passage resistance, so that a large cooling effect can be obtained and the capacity is several hundreds.
With a transformer up to KVA, cooling can be achieved without using an external radiator. Therefore, this type of tank is effective in reducing the size and weight of the transformer, and is widely used as a container for medium and small oil-immersed transformers.

When a conventional corrugated transformer tank is manufactured, first, a metal plate is corrugated so that peaks and valleys are alternately arranged in the longitudinal direction. Next, a hollow heat radiation fin portion is formed by sealing both ends of each peak portion of the metal plate by welding to form a corrugated plate for forming a tank side wall in which a large number of heat radiation fin portions are arranged in the longitudinal direction. Then, this corrugated plate is bent into a shape conforming to the shape of the side wall of the tank, and both ends in the width direction of the bent corrugated plate are formed into a shape that also conforms to the shape of the side wall of the tank. The bent upper and lower frames were welded to form a side wall of the tank.

As described above, when the method of bending the corrugated plate and the frame body into a shape suitable for the shape of the side wall of the tank and then welding is adopted, the corrugated plate and the frame body are used at the time of welding. The operation of aligning the tank was extremely troublesome, and the production efficiency of the tank was inevitably reduced.

Therefore, as seen in JP-B-62-48363, before the corrugated plate for forming the tank side wall and the frame member for forming the frame body are bent, the butted portion is welded over the entire length, Thereafter, a method of forming a side wall of the tank by performing a bending process has been proposed.

When a tank is manufactured by the method disclosed in Japanese Patent Publication No. 62-48363, as shown in FIG. 10, the end of the frame member 101 'is bent to the opposite side of the radiating fin portion 100a of the corrugated plate 100. To form a flange 101a ', and a notch 101b' is provided in a portion where the flange 101a 'is bent. And corrugated board
The butt portion is welded over the entire length by abutting the frame member 100 'with the frame member 101' before bending, and then the frame member 101 'is bent at the notch 101b'. Next, the notched portion 101b 'is closed and the frame-shaped butted portion is welded to form a notch.
As shown in FIG. 11, the frame 101 forms a tank side wall having a flange portion 101a projecting from the inner surface of the tank.

[Problems to be Solved by the Invention] As shown in JP-B-62-48363, if a method of bending after welding a frame member to a corrugated plate is adopted, the corrugated plate can be welded at the time of welding. Since the work of positioning the frame member can be easily performed, workability can be improved as compared with the conventional method in which the corrugated plate and the frame member are formed and then welded.

However, in the case of this method, it is necessary to provide the notch 101b 'in the flange 101a' of the frame member, and the joint of the notch portion butted into a frame shape after the bending process is welded to finish in a planar shape. Because of the necessity, the number of man-hours increases and the manufacturing cost increases.

In the tank manufactured by the above method,
There are many welds on the flange which is extremely important for airtight performance,
Moreover, since the welded portion is located at the corner of the tank, there is a possibility that the reliability of the airtight surface of the tank may be reduced.

Also, when the notch 101b 'is provided in the flange 101a' and bent as described above, the tank side wall is bent with a very small bending radius, so that the tank side wall is formed inside the corner. There is a problem that the dead space becomes large, which causes an increase in the amount of oil, which increases the weight of the product and increases the material cost.

Regardless of the above method, it is possible to bend and form the frame member without performing notch processing by bending the frame member into an arc shape with a considerably large curvature (bending radius of about several tens mm). . Such bending of the frame member is usually performed by a press machine using a convex mold and a concave mold.

However, when the bending process is performed by a press machine, during the pressing process in which the convex mold enters the concave mold,
There is a tendency that a strong bending is locally generated in a part of the frame body, and the flange portion or the curling portion at both ends of the frame member is deformed at the portion where the strong bending is generated (in a severe case, a crack is generated). . These deformations remain even after the completion of pressing, and tend to impair oil-tightness.

Also, since the bending position is likely to be shifted and the weight of the workpiece is large, the end of the workpiece may be greatly raised at the time of pressing and may be deformed or harmful to the operator.

An object of the present invention is to smoothly perform a uniform bending process at a portion to be bent without performing notch processing on a bent portion of a tank side wall structure and without causing local deformation of a frame body. It is an object of the present invention to provide a method for efficiently manufacturing a high-quality corrugated transformer tank.

Means for Solving the Problems The present invention provides a side wall structure forming step of forming a tank side wall structure, a bending step of bending the tank side wall structure to form a half of the tank side wall, and a tank. 2 half of the side wall
And a step of butting and joining the individual pieces to produce a transformer tank.

In the side wall structure forming step of this method, the metal plate is corrugated and formed such that peaks and valleys are alternately arranged in the longitudinal direction, and both ends of each peak are sealed by welding to form a hollow heat radiation fin. Is prepared, and an upper frame member and a lower frame member each having a flange portion or a curling portion at one end in the width direction are prepared. Then, the other ends in the width direction of the upper frame member and the lower frame member are overlapped on both end edges in the width direction of the corrugated plate, respectively, and the both frame members and the corrugated plate are corrugated along the overlapping portion of the corrugated plate. The tank side wall structure is formed by welding the plates.

In the bending step, the vicinity of both ends in the longitudinal direction of both frame members of the tank side wall structure is set as a bent portion, and the bent portion is bent to the same side to form a U-shaped tank side wall half.

The method of the present invention is an improvement of the bending step,
In the present invention, a lower mold having a processing surface in a shape corresponding to the shape of the bent portion of each of the upper frame member and the lower frame member of the tank side wall structure is provided, and the tank side wall structure is provided. The lower mold is applied to the bent portion of the upper frame member from the side opposite to the heat radiation fin portion. Then, after the upper frame member and the lower frame member are fixed to the lower mold, the upper molds are brought into contact with the respective bent portions of the upper frame member and the lower frame member to correspond to the respective upper dies. By pressing the upper mold at a predetermined pressure toward the lower mold to be rotated and rotating each upper mold along the processing surface of the lower mold while maintaining this pressure, the tank side wall structure is folded into a U-shape. Bending is performed to form a half of the tank side wall.

[Operation] When the bending process is performed as described above, the bending of the frame member is smoothly bent at a curvature determined by the curvature of the processing surface of the lower mold. Therefore, no local deformation occurs in the bent portion, and a smooth bent surface can be obtained.

Further, as described above, when the side die is applied to the flange portions or the curling portions at both ends in the width direction of the bent portion of the upper frame member and the lower frame member from the outside, respectively, the flange portion or the curling portion is formed. Does not protrude to the outside, so that molding can always be performed correctly.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

8 and 9 show the transformer tank 1 manufactured according to the embodiment of the present invention, and FIG. 8 shows a state where the cover plate is removed.

The transformer tank 1 includes a side wall 1A, a bottom plate 1B, and a cover plate 1C. The side wall portion 1A is formed by corrugating a relatively thin metal plate (usually a steel plate) that is easy to bend, and is formed by corrugating plate 2 formed with a number of radiating fins 2a. 3 and frame members 4 and 5 welded to both ends of the wall 3 in the width direction. In this example, two side walls 1A are formed by joining two tank halves 1a having a U-shaped cross section as shown in FIG. As shown in FIG. 9, the upper and lower frames 4 and 5 each have a curling portion 4a and a flange portion 5a, and the bottom plate 1B is welded to the flange portion 5a of the lower frame 5,
A cover plate is attached to the curling portion 4 a of the upper frame 4.

In order to manufacture the above-mentioned transformer tank, first, a metal plate is subjected to a corrugating process to form peaks m and valleys v alternately arranged in the longitudinal direction as shown in FIGS. 4 and 5. The longitudinal ends ma and mb of each peak m are sealed by squeeze welding to manufacture a corrugated plate 2 for forming a tank side wall in which a hollow radiating fin 2a is formed by each peak. This corrugated plate is arranged in a state where it is developed along one plane. In FIG. 5, the hatched portions indicate the hollow portions (oil passages) of the radiation fins.

Separately from the corrugated plate, an upper frame member 4 'forming the upper frame member 4 and a lower frame member 5' forming the lower frame member 5 are prepared.

As shown in FIG. 6 (C), the upper frame member 4 'is subjected to a curling process at one end in the width direction of a strip extending linearly in one direction so that the cross section thereof is formed in an arc shape. The portion 4a 'is formed continuously. As shown in FIG. 6 (B), the upper frame member 4 'extends along one end in the width direction of the corrugated plate 2 which is deployed and arranged along one plane. It is arranged in a state where it is partially overlapped with the end.

As shown in FIG. 6 (A), the lower frame member 5 'is formed by bending one end in the width direction of a linearly extending strip to continuously form a flat strip-shaped flange portion 5a'. It was done. The lower frame member 5 'is arranged along one end of the corrugated plate 2 in the width direction as shown in FIG.

An upper frame member 4 'and a lower frame member 5' are welded to both widthwise edges of the corrugated plate 2, respectively, to form a tank side wall structure 7 shown in FIG. 6 (B). W indicates a weld formed at this time.

Next, a bending process for bending the vicinity of both ends of the tank side wall structure 7 to the same side is performed. The direct bending force is applied during the bending process because the upper frame member 4 'and the lower frame member 5' are used.
Is only the bent portion (the portion to be bent) near both ends. Therefore, in this embodiment, FIG.
And four folding devices 10 as shown in FIG. 4B, and these four folding devices are used to fold a total of four places near both ends of the upper frame member and near both ends of the lower frame member. It is arranged in the bending part.

FIGS. 2 and 3 show the positional relationship between the four folding devices 10 and the tank side wall structure 7 by simply showing only the mold portion of the folding device. FIG. FIG. 3 is a side view. In FIG. 2, the upper frame member 4 'and the lower frame member 5' are arranged at a bent portion on one end side.
Although only the base folding devices 10 and 10 are shown, in practice, the bent portions on the other end sides of the upper frame member 4 'and the lower frame member 5' are located at positions symmetrical with respect to the XX axis shown in the figure. Two bending devices for processing are arranged. 4 folding devices 10
Are supported on a common base (not shown) so as to be position-adjustable, and the distance between the folding devices 10, 10 adjacent in the width direction of the tank side wall structure 7 (the distance in the XX axis direction) and The distance between the bending devices adjacent in the longitudinal direction of the tank side wall structure 7 (the distance in a direction perpendicular to the XX axis) is determined by the size of the tank side wall structure 7 and the position of the bent portion. It can be changed as needed.

In the present invention, the bent portion on one end side of the upper frame member 4 'and the bent portion on one end side of the lower frame member 5' are simultaneously bent by the bending devices 10 and 10, and the upper frame member 4 ' Is bent simultaneously by the bending devices 10 and 10 to form a U-shaped tank side wall half.

FIGS. 1 (A) and 1 (B) schematically show one of the folding devices 10 arranged on the lower frame member 5 'side together with the lower frame member. FIG. 4 is a view of the bending device viewed from the cut surface side. FIG. 1A shows a state before the start of bending, and FIG. 1B shows a state in the middle of bending.

1 (A) and 1 (B), reference numeral 11 denotes a lower mold, which has a machined surface corresponding to the shape of the bent portion of the lower frame member 5 'after bending. doing. This processing surface has flat first and second processing surfaces 11a and 11b provided at an angle slightly smaller than 90 degrees, and a cylindrical surface formed at a corner portion between these processing surfaces. 3 processing surface 11
The bent part of the frame member 5 'is bent along these processing surfaces.

The angle formed by the first and second processing surfaces 11a and 11b of the lower mold 11 is slightly (several degrees) smaller than 90 degrees because of the elasticity of the tank side wall structure when the bending is completed. This is because it is necessary to consider the springback that occurs.

The side mold 12 is mounted so as to cover a part of the processing surfaces 11a to 11c of the lower mold (see FIGS. 2 and 3). The side mold 12 is provided to press the flange portion 5a 'of the lower frame member 5' from outside and prevent the flange portion 5a 'from falling outside. The side mold 12 is mounted so as to be slidable in the XX axis direction, and thereby the position of the side mold 12 with respect to the lower mold is adjusted to the lower frame member 5 '.
(The position of the flange portion 5a '). That is, by adjusting the position of the side die 12, the width of the processing surface of the lower die 12 can be adjusted.

Above the lower mold 12, a clamper 13 and an upper mold including a small upper mold 14 and a large upper mold 15 are provided.

The clamper 13 is attached to a rotatable arm (not shown) having a fulcrum outside the tank side wall structure 7, and is clamped by a rotating mechanism using a cylinder as a driving source (the lower mold 12). The position between the upper frame member 5 ') and the retracted position (position away from the frame member) is displaced. The clamper 13 is urged toward the lower mold 11 while being located at the clamp position, whereby the frame member 5 ′ is clamped to the lower mold 11.

A movable frame 20 is rotatably supported on the lower mold 12 via a shaft (not shown) extending in a direction perpendicular to the paper surface of FIG. 1 (A). The sliding block 21 is mounted so as to be freely displaceable linearly. The sliding block 21 is a concave / convex fitting portion (not shown) that extends long in the longitudinal direction of the movable frame 20 (for example, a fitting between a dovetail-shaped groove and a convex portion).
And is guided by the concave and convex fitting portion so as to be displaceable only in the longitudinal direction of the movable frame.

Cylinder support section 20 provided at the upper end of movable frame 20
A large cylinder 22 is supported by a, and the tip of a piston rod 23 of the large cylinder is fixed to a protruding portion 21a provided at an intermediate portion of the sliding block 21. In addition, a small cylinder 24 is provided with a pin 25 on a protruding portion 21b provided on the side of the sliding block 21.
And is rotatably supported via the. These cylinders
22 and 24 are driven by hydraulic pressure such as hydraulic pressure or pneumatic pressure.

The small upper mold 14 is attached to the lower end of the piston rod 26 of the small cylinder 24 via a pin 27, and the large upper mold 15 is fixed to the lower end of the sliding block 21 with bolts, nuts and the like.
The small upper mold 14 is provided with a connecting plate 14a, and the connecting plate 14a is connected to the large upper mold 15 by pins 28.

The mold surface 14A of the small upper mold 14 is curved into a shape corresponding to the third processing surface 11c of the lower mold 11, and the mold surface 15A of the large upper mold 15 is formed flat. The corners at both ends of the mold surface of the small upper mold 14 and the large upper mold 15 are rounded.

As shown in FIG. 3, the upper dies 14 and 15 have cutouts 14b and 15b on their sides. Surfaces 14b1 and 15b1 of these notches 14b and 15b, which are orthogonal to the frame member, are
It abuts on a 'from inside to prevent the curling portion 4a' from falling down inside. The surfaces 14b2 and 15b2 of the notches 14b and 15b parallel to the frame member prevent the curling portion 4a 'from deforming in a direction to open outward.

Although not shown, as shown in FIG.
From the position where 15 is parallel to the processing surface 11a of the lower
A drive mechanism for displacing the movable frame 20 to a position where the large upper mold 15 is completely opposed to the processing surface 11b of the lower mold 11 via the position shown in FIG.

Bending device disposed at one end of lower frame member 5 '
The tenth configuration has been described, but the bending device shown in FIG.
10 and a bending device arranged on the other end side of the lower frame member 5 '
10 is symmetrical with respect to the YY axis in FIG. 1 (A). The folding device 10 disposed on one end side of the upper frame member 4 'is configured symmetrically with respect to the drawing surface of FIG. 1A, and is disposed on the near side of the drawing surface. ing. Similarly, a bending device disposed at the other end of the upper frame member 4 'and a bending device disposed at the other end of the lower frame member 5' (both not shown in FIG. 1). Fig. 1 (A)
Are symmetrical with respect to the paper surface of FIG.

Next, the bending step of bending the tank side wall structure 7 will be described. First, the distance between the four bending devices 10 is set according to the size of the tank side wall structure 7 and the position to be bent. Then, after placing the tank side wall structure 7 on the lower mold 11, the clamper 13 is operated to press and fix the tank side wall structure 7 to the lower mold 11.

Next, a fluid pressure is applied to the large cylinder 22 and the small cylinder 24 to push out the large piston rod 23 and the small piston rod 26.
FIG. 1A shows a state immediately after the upper molds (the large upper mold 15 and the small upper mold 14) have come into contact with the lower frame member 4 '.

In this state, the upper dies 15 and 14 are urged by the cylinders 22 and 24 to press the upper dies against the upper frame member 4 'and the lower frame member 5' with a predetermined pressure. The lower frame member 5 'is pressed against the surface 11a of the lower mold. The movable frame 20 is rotated clockwise in FIG. 1 while maintaining this pressurized state (pressure). At this time, the upper dies 15, 14 rotate from the first processing surface 11a side of the lower die to the second processing surface 11b side while pressing the upper frame member 4 'and the lower frame member 5', and Bend the bent part. FIG. 1 (B) shows a state in the middle of bending.

At the stage when the rotation of the upper mold is completed, the small upper mold 14 faces the third processing surface 11c of the corner of the lower mold 11, and the large upper mold 15 is the second mold 11 of the lower mold 11. It faces the processing surface 11b.

Since the bent portion of each frame member of the tank side wall structure 7 is fixed to the lower mold by the clamper 13, a tensile force acts on each frame member in the process of rotating the upper molds 15, 14. Even when the frame members are not displaced, the flat portions of the frame members facing the processing surface 11a do not bulge due to the reaction of the bent portions.

Further, in this embodiment, as shown in FIG. 3, cutouts 14b and 15b for restraining the curling portion or the flange portion are provided below the small upper mold 14 and the large upper mold 15,
The curling portion and the flange portion can be prevented from falling down inside or outside during the bending process, and the bending process can be performed smoothly without deforming the curling portion and the flange portion.

The bending force is directly applied by the mold only to the upper frame member 4 'and the lower frame member 5'. However, the rigidity of the corrugated plate in the bending direction is small. Accordingly, the corrugated plate also bends, and as shown in FIG. 7, a U-shaped tank side wall half 1a having an upper frame 4 having a curling portion 4a and a lower frame 5 having a flange portion 5a is formed. It is formed.

After the bending is completed, the large piston rod 23 and the small piston rod 26 are retracted by applying fluid pressure to the large cylinder 22 and the small cylinder 24 in the direction of pulling back the piston. As a result, the upper dies 14, 15 are separated from the tank side wall half 1a, and then the pressing by the clamper 13 is released. After taking out the tank side wall half 1a, the movable frame 20 is rotated in the direction opposite to the direction at the time of bending to return to the original position.

The two tank side wall halves 1a obtained as described above are butted together and the butted portions are welded to form a tank side wall portion 1A.
Is configured.

Thereafter, as shown in FIG. 9, the bottom plate 1B is welded to the flange of the lower frame 5 to complete the transformer tank. The lid plate 1C is attached to the curling portion of the upper frame 4 via the packing 8 after storing the transformer main body together with the insulating oil in the tank.

As described above, in the bending method of the present invention, by moving the upper mold along the processing surface of the lower mold while holding the frame member of the tank side wall structure 7 with the clamper 13, Since the frame member is deformed along the processing surface of the lower die, each frame member can be bent without difficulty at the curvature determined by the processing surface of the lower die. Thereby, the bending process can be performed efficiently without causing any displacement of the bent portion and without causing local deformation of the bent portion or deformation of the curling portion or the flange portion.

In the above embodiment, the upper mold is composed of two molds, a large mold and a small mold. However, it is not always necessary to use two molds. (For example, in the above embodiment, the small upper mold 14 is peeled off,
15 only).

As in the above embodiment, when configured to be able to slide in the width direction of the frame member with respect to the lower mold of the side mold,
Since the width of the processing surface of the lower mold can be changed as appropriate, it is economical to change the width of the upper frame member and the lower frame member only by replacing the upper mold.

[Effects of the Invention] As described above, according to the present invention, the frame member is rotated by rotating the upper die applied to the bent portion of the frame member along the processing surface of the lower die. Since it is smoothly bent along the processing surface of the lower mold, a smooth bent surface can be obtained without causing local deformation in the bent portion.

Also, in order to advance the processing in a state where the side mold is applied to the flange portion or the curling portion at both ends in the width direction of the bent portion of the upper frame member and the lower frame member from the outside, respectively.
The bending process can be performed without causing undesired deformation of the flange portion or the curling portion.

Furthermore, when the tank containing the transformer is closed, the bending process can be performed without providing a notch in the flange portion or the curling portion serving as the packing contact surface, so that it is necessary to form a welded portion in the bent portion. Absent. Therefore, it is possible to obtain a corrugated transformer tank having excellent airtightness and high reliability.

[Brief description of the drawings]

1 (A) and 1 (B) show a bending device used in an embodiment of the present invention together with a lower frame member. FIG. 1 (A) is a side view showing a state before bending, and FIG. (B) is a side view showing a state during bending. FIGS. 2 and 3 are a plan view and a side view, respectively, showing only the mold part of the bending device used in the embodiment of the present invention in a simplified form together with the tank side wall structure, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a perspective view showing a corrugated plate used in the example, FIG.
6A is a perspective view showing a lower frame member used in the embodiment of the present invention, FIG. 6B is a perspective view showing a tank side wall structure used in the embodiment of the present invention, and FIG. FIG. 7 is a perspective view showing an upper frame member used in the embodiment, FIG. 7 is a perspective view showing a tank side wall half part constituting a tank side wall in the embodiment of the present invention,
FIG. 8 is a perspective view showing a state in which a lid plate of a manufactured transformer tank is removed, FIG. 9 is a sectional view schematically showing a structure of a transformer tank obtained according to an embodiment of the present invention, and FIG. FIG. 11 and FIG. 11 are perspective views showing a tank side wall before and after bending according to the conventional method, respectively. 1 ... Transformer tank, 1A ... Side wall, 1B ... Bottom plate, 1C ...
... lid plate, 2 ... corrugated plate for forming tank side wall, 2a ... radiation fin part, 3 ... radiation wall part, 4 ... upper frame, 5 ... lower frame, 4 '... upper frame member , 5 '... lower frame member, 7
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….
Side mold, 13 ... Clamper, 14 ... Small mold, 15 ...
Large mold, 20 …… Movable frame, 21 …… Sliding block,
22… Large cylinder, 24… Small cylinder.

Claims (1)

(57) [Claims] 1. A tank side wall having a hollow radiating fin portion formed by corrugating a metal plate so that peaks and valleys are alternately arranged in the longitudinal direction and sealing both ends of each peak by welding. A corrugating plate for configuration, an upper frame member and a lower frame member having a flange portion or a curling portion at one end in the width direction are prepared, and an upper frame member and a lower frame are respectively provided at both ends in the width direction of the corrugated plate. Overlap the other end in the width direction of the member,
Forming a tank side wall structure by welding the two frame members and the corrugated plate along the overlapped portion of the two frame members and the corrugated plate; and a longitudinal direction of the two frame members of the tank side wall structure. A bending process of forming a U-shaped tank side wall half by bending the bent portion to the same side with the vicinity of both end portions as a bent portion, and joining two tank side wall halves to each other And the step of manufacturing a transformer tank, the bending step, the shape corresponding to the shape after bending of each of the bent portion of the upper frame member and the lower frame member of the tank side wall structure Providing a lower mold having a processing surface of, and applying the lower mold to a bent portion of an upper frame member and a lower frame member of the tank side wall structure from a side opposite to the heat radiation fin portion; Upper frame member and lower frame member After the side mold is applied to the flange portion or the curling portion at both ends in the width direction of the bent portion from outside, the upper frame member and the lower frame member are respectively fixed to the lower mold, and then the upper frame member is fixed. The upper mold is brought into contact with each bent portion of the lower frame member and each upper mold is pressed at a predetermined pressure toward the corresponding lower mold, and each upper mold is maintained while maintaining the pressure. Wherein the tank side wall structure is bent into a U-shape to form a half of the tank side wall by rotating the tank side wall along the processing surface of the lower mold. .