JPH0541581A - Molded case for electronic component - Google Patents

Abstract

PURPOSE:To provide a molded case in which a mold is inexpensive, a strength of a product is strong and an external appearance is satisfactory in the molded case for a communication terminal device, etc., and particularly an improvement for a vent port. CONSTITUTION:In a case in which outer walls 21 each having a thickness smaller than 1/2 of a thickness of a case wall 2 and an outer surface coincident with that of the wall 2, and inner walls 22 each having a thickness smaller than 1/2 of a thickness of the wall 2 and an inner surface coincident with that of the wall 2, are alternately arranged in a zigzag manner thereby to array recesses 4 at desired positions of the wall 2 in one row in such a manner that gaps between the walls 21 and 22 formed on the sidewalls of the recesses 4 are used as vent ports 5, arc-shaped sectional protrusion stripes 25 are formed on a center line of the inner surface 21A of the outer wall 21.

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 communication terminal equipment and the like, and more particularly to improvement of a ventilation port.

2A and 2B are views of a molded case, wherein FIG. 2A is an overall perspective view, and FIG. 2B is a partially cutaway perspective view of a main part. 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 open upper surface, and an open lower surface. It is constructed by combining with a shallow box-shaped upper case, and the wall thickness of the case wall 2 is made as thin as possible so that desired electronic devices can be incorporated in the inside with high density.

On the other hand, in order to dissipate the heat generated by the accommodated electronic device, ventilation holes 5 are arranged on the ridge of the case 1. As shown in FIG. 2 (B) for details, the ventilation port 5 is
The outer wall 21 and the inner wall 22 are alternately arranged in a staggered manner to form the recesses 4 having a rectangular shape in plan view 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 port 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 molding die for molding the case as described above has a good workability without using a special steel or the like which has a long life but is hard and poor in 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, (A) is a sectional view of a case, and (B) is a sectional view of a molding die.

As shown in FIG. 3 (A), the conventional ventilation port 5 has a rectangular cross section whose outer surface matches 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 a rectangular cross section whose inner surface corresponds to the inner surface of the case wall 2 and whose wall thickness is approximately 1/3 of the wall thickness of the case wall 2 are alternately arranged in different steps. By arranging the recesses 4 in a row at a desired position on the case wall 2, the outer wall 21 formed on the side wall of the recess 4 is formed.
It is an elongated gap between 0 and the inner wall 22.

That is, when the wall thickness of the case wall 2 is 2.5 mm, the opening width of the ventilation port 5 is about 0.8 mm and the length is desired to be long. It is released to the outside after passing 5.

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

When the ventilation port 5 is provided as described above, the external wall
Due to the thin wall thickness of 210 and the inner wall 22, the flow resistance of the resin at the time of molding becomes large, and as a result, poor flow, gas burning, etc. occur, resulting in poor appearance (weld that does not look good). Line, sticking of resin, etc.)
Alternatively, the mechanical strength becomes insufficient.

Therefore, the outer wall forming core surface of the core 320
Drilling holes in each of 330 and the inner wall forming core surface 34,
Insert the gas release pin 35 into the hole, and discharge the air generated in the mold and the gas generated from the resin to the outside of the mold through the gap between the inner wall of the hole and the outer peripheral surface of the gas release pin 35. This prevents the occurrence of flow defects and gas burning.

[0011]

By providing the degassing pin 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 core material has been changed from aluminum to steel.

Since the core material is changed to the steel material, it takes a long time to process the core, which causes a problem that the cost of the molding die and the case becomes high.
The present invention was created in view of the above points, and an object of the present invention is to provide a molded case in which the molding die has a low cost, the mechanical strength of the product is strong, and the appearance is good.

[0013]

In order to achieve the above object, the present invention, as illustrated in FIG. 1, has a wall thickness smaller than 1/2 of the wall thickness of the case wall 2 and an outer surface of the case wall 2. Of the outer wall 21 and the inner wall 22 of which the wall thickness is less than 1/2 of the wall thickness of the case wall 2 and the inner surface of which matches the inner surface of the case wall 2.
By alternately arranging and, the concave portions 4 are arranged in a line at a desired portion of the case wall 2, and a gap formed between the outer wall 21 and the inner wall 22 formed in the side wall of the concave portion 4 has a ventilation port 5 In the above case, 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, among the thin outer wall and the thin inner wall forming the ventilation port, the 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 size of the ventilation port does not change, and the thickness of the outer wall is substantially increased. Therefore, the flow resistance of the resin flowing through the outer wall portion at the time of molding is small.

Therefore, since it is not necessary 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 without any problem, the processing cost of the molding die is low and the cost of the molding die is low.

The unit price of aluminum is about three times that of steel, but the weight ratio is about 1/3 that of steel, so that the material cost of the entire molding die remains almost unchanged.

[0017]

The present invention will be described in detail with reference to the drawings. The same reference numerals denote the same objects throughout the drawings.

FIG. 1 is a diagram of an embodiment of the present invention, (A) is a sectional view of a case, and (B) is a sectional view of a molding die. Figure 1
In, the ventilation port 5 has an outer surface that matches the outer surface of the case wall 2 and a wall thickness that is approximately 1/3 of the wall thickness of the case wall 2, and an inner surface that matches the inner surface of the case wall 2 and has a wall thickness of By arranging the inner walls 22 having a rectangular cross-section, which is approximately 1/3 of the wall thickness of the case wall 2, alternately in different steps and arranging the recesses 4 in a desired position on the case wall 2, the recesses are formed. External wall 21 formed on the side wall of No. 4
And the inner wall 22 is an elongated gap.

A protrusion 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 shape which is convex inward. Therefore, if the wall thickness of the case wall 2 is 2.5 mm, the opening width of the ventilation opening 5 is about 0.8 mm as in the conventional case, and the opening dimension of the ventilation opening 5 does not change at all. And the outer wall is provided with the protruding band 25.
The inner wall of 21 will be inclined diagonally upward, and will function as a ventilation guide. Therefore, ventilation is improved.

On the other hand, as shown in FIG. 1B, the molding die for molding the case 1 has a cavity 31 attached to the fixed side die and a core 32 attached to the movable side die. Molded by matching the mold.

At this time, as described above, the wall thickness of the outer wall 21 is substantially increased by providing the protruding band 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 at the time of molding is small. For this reason, shot molding, gas burning, etc. will not occur in the outer wall 21 portion without providing the gas releasing pin 35 on the outer wall forming core surface 33.

On the other hand, the wall thickness of the inner wall 22 is thin as in the conventional case, and therefore the core wall forming core surface 34 is provided with the degassing pin 35. As described above, the core 32 in which the degassing pin 35 is provided only on the inner wall forming core surface 34 does not decrease in strength because the degassing pin 35 is provided. Therefore, the material of the core 32 can be made of aluminum without any problem.

The unit price of aluminum is about three times that of steel, but the weight ratio is about 1/3 that of steel, so the material cost of the molding die as a whole remains almost unchanged. On the other hand, since aluminum is easier to process than steel, the processing cost of the cavity 31 and the core 32 is low. Therefore, the cost of the molding die is low.

[0024]

INDUSTRIAL APPLICABILITY As described above, the present invention is a mold forming case for an electronic device in which the cross-sectional shape of the outer wall forming the ventilation port is a semi-cylindrical shape with a convex inner surface, and the molding die is low in cost. Therefore, the cost of the case itself becomes low.

Further, since there is no flow failure, gas burning, etc., the case has high mechanical strength and a good appearance. Further, the provision of the protrusion band on the inner surface side of the outer wall causes the inner wall to incline obliquely upward, which has the effect of serving as a guide for ventilation and improving ventilation.

[Brief description of drawings]

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

FIG. 2 is a view of a molded case, (A) is an overall perspective view, and (B) is a partially cutaway perspective view of a main part.

FIG. 3 is a diagram of an embodiment of the present invention, (A) is a sectional view of a case, and (B) is a sectional view of a molding die.

[Explanation of symbols]

1,10 cases, 2 case walls,
4 recesses, 5 ventilation openings, 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 protruding band,

Claims (1)

[Claims] 1. An outer wall (2) whose wall thickness is less than 1/2 of the wall thickness of the case wall (2) and whose outer surface conforms to the outer surface of the case wall (2).
1) and the inner wall (22) whose wall thickness is less than 1/2 of the wall thickness of the case wall (2) and whose inner surface corresponds to the inner surface of the case wall (2) are arranged alternately. Thus, the recesses (4) are arranged in a line at a desired position 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). In the case where the gap is the ventilation port (5), 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). Molded case.