JP2861506B2 - Molded case for electronic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded case for a communication terminal device or the like, and more particularly to an improvement of a ventilation port.

FIGS. 2A and 2B are views of a molded case, wherein FIG. 2A is an overall perspective view, and FIG. As shown in FIG. 2, electronic devices such as communication terminal devices are required to be smaller and lighter, and the case 1 has a shallow box-shaped lower case formed by molding synthetic resin and having an upper surface opened, and a lower surface formed by opening. It is constructed by combining a shallow box-shaped upper case, and the thickness of the case wall 2 is made as thin as possible so that a desired electronic device can be incorporated therein at high density.

On the other hand, in order to radiate the heat generated by the housed electronic device, ventilation holes 5 are arranged at the ridge of the case 1. As shown in FIG. 2 (B) in detail,
The outer wall 21 and the inner wall 22 are alternately arranged stepwise, and the rectangular recesses 4 in plan view are arranged on the case wall 2, and the gap between the outer wall 21 and the inner wall 22 formed on the side wall of the recess 4 is formed. The ventilation opening 5 prevents foreign matter from entering the case and improves the appearance.

Further, in recent years, the material of the cavity 31 and the core 32 of the mold for molding the above-mentioned case has a long service life, but does not use special steel or the like which is hard and has poor workability. By using aluminum which is good and has a relatively long life of about 10,000 shots, cost reduction of molded products is being promoted.

[0005]

2. Description of the Related Art FIG. 3 is a view of a conventional example, in which (A) is a sectional view of a case and (B) is a sectional view of a mold.

As shown in FIG. 3A, the conventional ventilation port 5 has a rectangular cross section whose outer surface coincides with the outer surface of the case wall 2 and whose wall thickness is approximately 1/3 of the wall thickness of the case wall 2. The outer wall 210 and the inner wall 22 having an inner surface coinciding with the inner surface of the case wall 2 and having a rectangular cross section having a thickness of approximately 1/3 of the thickness of the case wall 2 are alternately arranged in steps. By arranging the recesses 4 in a desired position on the case wall 2 in a line, the outer wall 21 formed on the side wall of the recess 4
It is an elongated gap between 0 and the inner wall 22.

That is, assuming that the thickness of the case wall 2 is 2.5 mm, the opening width of the ventilation port 5 is approximately 0.8 mm and the length is desirably long, so that the heat of the electronic device accommodated in the case 10 is generated by this ventilation port. It is released to the outside via 5.

Further, since the opening width of the ventilation port 5 is as small as about 0.8 mm, foreign substances are prevented from entering the case 10 from the ventilation port 5. On the other hand, as shown in FIG. 3B, a mold for molding the case 10 includes a cavity 31 attached to the fixed mold and a core 320 attached to the movable mold.
It is a combination of

When the ventilation port 5 is provided as described above, the external wall
Due to the small thickness of the inner wall 210 and the inner wall 22, the flow resistance of the resin at the time of molding increases, resulting in poor flow, gas burning, etc., resulting in poor appearance (weld which may impair the appearance). Line, resin burnt, etc.)
Alternatively, the mechanical strength becomes insufficient.

Therefore, the outer wall forming core surface of the core 320
Drill holes in each of 330 and the inner wall forming core surface 34;
The gas vent pin 35 is inserted into the hole, and the gas generated from the air and resin in the mold is discharged out of the mold through the gap between the inner wall of the hole and the outer peripheral surface of the gas vent pin 35. As a result, the occurrence of poor flow, gas burning, etc. is prevented.

[0011]

By providing the gas vent pins on the core side as described above, the thickness of the side surface of the protruding portion corresponding to the outer wall of the core becomes thin, resulting in insufficient strength. For this reason, the material of the core has been changed from aluminum to steel.

Since the core material is changed to steel, it takes a long time to process the core, and there is a problem that the cost of the mold and the case becomes high.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a molded case in which a mold is inexpensive, has high mechanical strength of a product, and has a good appearance.

[0013]

In order to achieve the above object, the present invention, as illustrated in FIG. 1, has a thickness smaller than 1/2 of a thickness of a case wall 2 and an outer surface of the case wall 2. And an inner wall 22 whose thickness is smaller than 1/2 of the wall thickness of the case wall 2 and whose inner surface matches the inner surface of the case wall 2.
Are alternately arranged in a stepwise manner, so that the concave portions 4 are arranged in a line at desired positions of the case wall 2, and the gap between the outer wall 21 and the inner wall 22 formed on the side wall of the concave portion 4 is formed through the ventilation port 5. In the case described above, the projection wall 25 having an arc-shaped cross section is provided on the center line of the outer wall inner surface 21A of the outer wall 21.

[0014]

According to the present invention, of the thin outer wall and the thin inner wall constituting the ventilation port, a projection band having an arc-shaped cross section is provided on the center line of the inner surface of the outer wall of the outer wall. That is, the thickness of the outer wall is substantially increased without changing the size of the ventilation port. Therefore, the flow resistance of the resin flowing through the outer wall portion during molding is small.

Therefore, since there is no need to provide a gas vent pin on the outer wall forming core surface, there is no fear of insufficient strength of the core. That is, since the material of the core as well as the cavity is made of aluminum, there is no problem. Therefore, the processing cost of the mold is small, and the cost of the mold is low.

Although the unit price of aluminum is almost three times that of steel, the weight ratio is almost 1 / of that of steel, so that the material cost of the entire mold is almost the same.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The same reference numerals indicate the same objects throughout the drawings.

FIG. 1 is a view of an embodiment of the present invention, in which (A) is a sectional view of a case, and (B) is a sectional view of a mold. FIG.
In the ventilation hole 5, the outer wall has an outer wall corresponding to the outer wall of the case wall 2 and the wall thickness is approximately 1/3 of the wall thickness of the case wall 2, and the inner wall corresponds to the inner wall of the case wall 2 and has a wall thickness. By arranging the inner walls 22 having a rectangular cross section approximately 1/3 of the wall thickness of the case wall 2 alternately and stepwise, and arranging the concave portions 4 at desired positions of the case wall 2 in a line, the concave portions are formed. External wall 21 formed on the side wall 4
And the inner wall 22 is an elongated gap.

A projecting band 25 having an arc-shaped cross section is provided on the center line of the outer wall inner surface 21A of the outer wall 21, so that the outer wall 21 has a semi-cylindrical cross-sectional shape. Therefore, assuming that the thickness of the case wall 2 is 2.5 mm, the opening width of the ventilation port 5 is approximately 0.8 mm as in the conventional case, and the opening dimension of the ventilation port 5 is not changed at all. And the provision of the protruding band 25 makes the outer wall
The inner wall of 21 is inclined obliquely upward and functions as a ventilation guide. Therefore, ventilation is improved.

On the other hand, as shown in FIG. 1B, a mold for molding the above-mentioned case 1 includes a cavity 31 attached to a fixed mold and a core 32 attached to a movable mold. Molded and molded.

At this time, as described above, the thickness of the outer wall 21 is substantially increased by providing the protruding strip 25 on the inner surface 21A of the outer wall of the case 1. Therefore, the flow resistance of the resin flowing through the outer wall portion during molding is small. For this reason, shot molding, gas burning, and the like do not occur on the outer wall 21 portion even if the gas releasing pin 35 is not provided on the outer wall forming core surface 33.

On the other hand, since the thickness of the inner wall 22 is thin as in the prior art, a degassing pin 35 is provided on the inner wall forming core surface 34. As described above, the strength of the core 32 in which the degassing pins 35 are provided only on the inner wall forming core surface 34 does not decrease because the degassing pins 35 are provided. Therefore, there is no problem at all when the material of the core 32 is aluminum.

Although the unit price of aluminum is almost three times that of steel, the weight ratio is almost 1/3 that of steel, so that the material cost of the entire mold is almost the same. On the other hand, aluminum is easier to process than steel, so the cost of processing the cavity 31 and the core 32 is lower. Therefore, the cost of the mold is reduced.

[0024]

As described above, the present invention relates to a molding case for an electronic device in which the cross-sectional shape of the outer wall constituting the ventilation port is formed in a semi-cylindrical convex shape, and the molding die has a low cost. , The cost of the case itself is reduced.

Further, since there is no poor flow, no gas burn, etc., the mechanical strength of the case is high and the appearance is good. Furthermore, the provision of the protruding band on the inner surface side of the outer wall has the effect that the inner wall is inclined obliquely upward and functions as a ventilation guide to improve ventilation.

[Brief description of the drawings]

FIG. 1 is a view of an embodiment of the present invention, wherein (A) is a sectional view of a case, and (B) is a sectional view of a mold.

FIG. 2 is a view of a molded case, in which (A) is an overall perspective view and (B) is a partially broken perspective view of an important part.

FIG. 3 is a view of an embodiment of the present invention, wherein (A) is a cross-sectional view of a case, and (B) is a cross-sectional view of a mold.

[Explanation of symbols]

1,10 cases, 2 case walls,
4 recess, 5 vent, 2
1, 210 outer wall, 21A, 210A outer wall inner surface, 22 inner wall, 31 cavity, 32,320 core, 33,330 outer wall forming core surface, 34 inner wall forming core surface, 35 degassing pin, 25 protrusion band,

Claims (1)

(57) [Claims] An outer wall (2) whose thickness is smaller than 1/2 of the thickness of the case wall (2) and whose outer surface matches the outer surface of the case wall (2).
1) and an inner wall (22) whose wall thickness is smaller than 1/2 of the wall thickness of the case wall (2) and whose inner surface coincides with the inner surface of the case wall (2) are alternately arranged stepwise. Thus, the recesses (4) are arranged in a row at desired positions of the case wall (2), and the space between the outer wall (21) and the inner wall (22) formed on the side wall of the recess (4) is formed. In a case where the gap is a ventilation opening (5), an arc-shaped projecting band (25) is provided on the center line of the inner surface (21A) of the outer wall of the outer wall (21). Molded case.