JPS6044048B2 - Manufacturing equipment for corrugated heat sinks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for manufacturing a corrugated heat sink used for, for example, an outer casing of a transformer.

[Technical background of the invention and its problems] In general, self-cooling oil-immersed transformers conduct heat generated from windings and iron cores to cooling oil, and the thermal energy of the warmed oil is transferred through heat exchange. The heat is transferred to the tank wall of the oil-immersed transformer by convection, and the heat can be radiated into the air through heat radiating ribs formed on the tank wall.

In particular, this type of heat sink having heat dissipation ribs is formed by deep drawing a grooved plate into a corrugated shape in order to improve heat dissipation efficiency. That is, as shown in FIG. 1, a heat radiating plate a having a large number of ribs a spaced at predetermined intervals is formed by deep drawing a thin plate by press working.

When this heat dissipation plate a is used as a tank wall of an inrush transformer, both ends of each rib a are pressed and welded as shown in Fig. 2, and the ribs of the bag body inside which cooling oil circulates are formed. a,
to form. However, the rib a of the bag body like this,
When molding, there was a risk that cracks b would occur at the rising bases of ribs a. To explain this with reference to FIGS. 3 to 5, a thin plate such as a steel plate is placed horizontally on a die having grooves (not shown), and then the thin plate is held with a vertically movable holding member. Temporarily fixed, the thin plate is press-fitted into the groove of the die using a punch provided on this holding member to form a heat dissipating plate a having ribs a1 as shown in FIG.
to form. Here, the thickness of the thin plate of the corrugated heat sink a is t1 the pitch between the ribs a1 is P1, its midpoint is C1, the starting point of the curvature part at the rising base of rib a1, the end points are A and B, the curvature of the curvature part is R, Let G be the distance between the opposing side walls of the rib a. In the next molding process, as shown in FIG. 4, both open ends of the rib a1 are simply pressed with a mold.
At this time, point B moves by G/2, and the curvature of the rising base becomes r
Since (r<R), the thin plate is stretched by the amount between C and B, and as a result, pressure is locally applied to the thin plate, which causes cracks to occur.

Therefore, as shown in FIG. 5, a corrugated heat dissipating plate a having pre-formed ribs a1 is inserted into a splittable die d that narrows and narrows the rising base of the ribs a1.
For example, urethane rubber w is preset and press-fitted from below using a punch f provided on the wrinkle holding member e, and the rib Al of the corrugated heat sink a is pressed. After forming the throat part on the rising base of the rib a1, as mentioned above, a method is being considered in which both ends of each rib a1 are pressed and welded, but this requires the number of forming process steps (in this case, three steps). Not only is it difficult to achieve labor savings through mass production as the number of pre-orders increases, but it is also difficult to achieve labor savings through mass production. There is also the disadvantage that the elastic body such as urethane rubber w that is press-fitted in the set is burnt out due to processing heat, shortening its life.Also, there is also a method using hydraulic pressure, but this requires a complicated structure of the sealing device and split mold, and The overall size of the equipment also became large, making it difficult to save labor through mass production.

[Purpose of the invention]

In view of the above-mentioned points, the present invention has been devised so that when pressing both ends of the rib in a corrugated heat sink, no cracks are generated at the rising base of the rib, the number of processing steps can be reduced, and production efficiency can be improved. The present invention provides an apparatus for manufacturing a corrugated heat sink for the purpose of the present invention.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIGS. 6 to 10, reference numeral 1 designates a pair of dies each having a vertically movable upper ram 2 in a brace device, each of which has a fixed no end and a free end.

The pair of dies 1 can be bent about the fixed end, and therefore each free end can be displaced in a direction away from each other, and when being displaced, the free ends are pressed in a direction toward each other. constructed with the resilience to The pair of dies 1 have throat portions 1a formed inside their free ends and projecting in directions opposite to each other. Directly below the pair of dies 1, a wrinkle pressing member 3 fixed to the bolster of the brace device is provided so as to place a thin plate 4 that moves along the direction in which the pair of dies 1 are juxtaposed. An opening 3a is provided in the center of this wrinkle pressing member 3, and a pair of punch guides 5 are attached to this opening 3a so that they can move forward and backward elastically by the elasticity of each spring 6. has been done. Further, a punch 7 is provided on the wrinkle pressing member 3 so as to be resiliently held by the punch guide 5 and guided in the vertical direction, and the upper end 7a of the punch 7 is provided with an opening 3a. It is provided so that it can be raised and lowered by a lower ram (not shown) so that the thin plate 4 can be inserted between the pair of dies 1. The thickness of this punch 7 along the direction in which the pair of dies 1 are juxtaposed is such that the upper end 7
A is formed to be thick so as to have a required spacing between the opposite side walls of the ribs, and a portion 7b located below it is formed to be thinner, and the boundary between the two portions is formed into a smooth curved surface. In addition, when this punch 7 is lowered, the wrinkle pressing member 3
It moves downward from the upper surface, and when raised, can move up and down until the upper end 7a is located above the throat parts 1a of the pair of dies 1. Therefore, in order to form the corrugated heat sink 8 having the recesses 8a and ribs 8b shown in FIG. 6, the thin plate 4 is placed horizontally on the wrinkle pressing member 3 as shown in FIG. , the upper ram 2 and the pair of rams 1 are lowered to temporarily fix the thin plate 4. Next, when the punch 7 integrated with the lower ram is raised, the upper end 7a of the punch 7 interposes the thin plate and enters between the pair of dies 1 by widening the gap between the throat parts 1a. When the punch 7 extrudes and molds the thin plate 4 a little, the pair of dies 1 is raised so as to be a little apart from the thin plate 4 and the wrinkle pressing member 3, so that the thin plate 4 is not pressed by the die 1.
Next, as shown in FIG. 9, the punch 7 is inserted into the upper end 7a.
is inserted into the throat portion 1 of the pair of dies 1 with the thin plate 4 interposed therebetween.
10, and then further inserted while being guided by the punch guide 5 until it is located above the throat portions 1a of the pair of dies 1, as shown in FIG. In this way, the throat parts 1a of the pair of dies 1 move from the upper end 7a of the punch 7 to the thinner part 7b, are positioned facing each other, and are pressed by the restoring force through the thin plate 4 so as to narrow the gap. As a result, the thin plate 4 not only forms a rib 8b having the necessary distance between opposite side walls by the cooperation between the upper end 7a of the punch 7 and the throat 1a of the die 1, but also has a thickness greater than that of the upper end 7a of the punch 7. The thin portion 7b and the throat portion 1a of the tie 1 form a concave portion 8a at the rising base of the rib 8b with a narrower distance between opposing side walls. In addition, just before the molding process is completed,
After pressing the pair of dies 1 against the wrinkle pressing member 3 again, the upper end 7a of the punch 7 is pressed to the position shown by the dotted line in FIG.
is raised to finish forming the rib 8b to a predetermined overhang length. In this way, the rib 8b having one recess 8a
After molding, the die 1 integrated with the ram 2 is pulled up and the punch 7 is lowered down, and then the thin plate 4 is shifted by a pitch to perform the next rib molding process.
In the next processing step, the corrugated heat sink 8 in which a large number of ribs 8b having the recesses 8a are formed at predetermined intervals is pressed against both ends of each rib 8b, as shown in FIG. It is designed to be welded and formed into a bag body. Here, if the elongation of the thin plate 4 in the process of forming the ribs 8b of the corrugated heat sink 8 is expressed in accordance with FIG. 3 and equation (1), it will be elongated by the amount shown in FIG. , compared to the above equation (1), the required distance between opposing side walls of the rib 1 G(7
) decreases by 1h.

Therefore, the smaller the side wall distance g of the recess 8a, the easier it becomes to press both ends of the rib 8b.

Therefore, as shown in FIG. 7, by forming the recess 8a, when pressing both ends of the rib 8b to form a bag, the end of the thin plate is pulled by the amount that the thin plate stretches less. This can prevent deformation and cracking of thin plates. Furthermore, the oil flow within the rib 8b is controlled by the narrow gap formed by the recess 8a in the direction in which the rib 8b extends as shown in FIG. It has become possible to promote turbulence in the air and improve heat dissipation efficiency.

Next, the embodiment shown in FIG. 11 is another embodiment of the present invention, in which the bases of the pair of dies 1 are rotatably fixed to the upper ram 2 by pins 9, and pair of dies 1
A hydraulic cylinder? The die 1 is connected at the holder 10 so that the displacement of the free end of the die 1 and the magnitude of the restoring force can be freely changed, and is substantially the same as the above-mentioned specific example.

〔Effect of the invention〕

As described above, according to the present invention, the throat parts protruding in mutually opposing directions are formed at the free ends of the pair of dies integrated with the upper ram, and the wrinkle pressing member is provided directly below the pair of dies. A pair of punch guides are attached to the opening of the wrinkle holding member so as to be able to move forward and backward elastically, and a punch guided by the punch guides is inserted into the opening of the wrinkle holding member. The rib is formed so that it is thick at the end and thinner at the bottom so that it can be inserted between a pair of dies through a thin plate until it is located above the throat of the die. Now it can be processed in one molding process,
It has excellent effects such as being able to save labor through mass production and eliminating the risk of cracking during molding.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a part of the corrugated heat sink that has already been proposed, FIG. 2 is a perspective view showing the corrugated heat sink with both ends pressed together, FIGS. Figure 4 is a diagram for explaining the elongation of the ribs of the above-mentioned corrugated heat sink using a mathematical formula.
FIG. 5 is a diagram showing only the main parts of a manufacturing apparatus for a corrugated heat sink that has already been proposed, FIG. 6 is a perspective view of a corrugated heat sink according to the present invention, and FIG. 7 is a corrugated heat sink shown in FIG. 6. FIG. 8 is a sectional view showing only the main parts of the corrugated heat sink manufacturing apparatus according to the present invention, and FIGS. 9 and 10 are for explaining the details of the present invention. Figure for, No. 11
The figure shows another embodiment of the invention.

1... Pair of dies, 1a... Throat, 2
...Upper ram, 3...Formation pressing member, 4
... Thin plate, 5 ... Punch guide, 7.
...Punch, 8a...Recess, 8b...
...Rib, 8...Corrugated heat sink.

Claims (1)

[Claims] 1. An upper ram that is movable up and down; one end of each of the upper rams is fixed, the other end is a free end, and each of the free ends is formed with a throat that projects in a direction toward each other, and each of the free ends A pair of dies are configured such that the parts can be displaced in a direction away from each other, but have a restoring force so as to press them toward each other when the parts are displaced, and a thin plate is placed directly below the pair of dies. a presser member provided with a
A pair of punch guides are attached to the wrinkle pressing member and can move forward and backward elastically, and the thickness along the direction in which the pair of dies are arranged is The upper end portion is thick and the portion below the upper end portion is thin, and during the upward movement, the upper end portion is positioned between the pair of dies via the thin plate above the throats of the pair of dies. A corrugated heat sink manufacturing device consisting of a punch that can be inserted until the