JP2000071292A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding for prolonging a lifetime of the mold by reducing a wear caused by a contact between mold members such as the core, the body or the like. SOLUTION: The mold 10 for injection molding comprises slide cores 12, 13. The core 12 has a smooth surface 12c formed on a slidably contact part of the core 13 with a male mold 13d in the case of opening or clamping the mold of the core 12. A smooth surface is also formed on a periphery of the mold 13d of a substantially columnar state of the core 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold, and more particularly, to an injection mold characterized by a sliding surface between slide cores or a sliding surface between a slide core and a mold body. About.

[0002]

2. Description of the Related Art Recently, magnetic recording / reproducing apparatuses such as video cameras and video tape recorders are often used outdoors. For example, small digital video cameras with good portability are frequently used for photographing outdoor landscapes, people, and the like. A digital video cassette tape (DV
A magnetic tape cassette such as C) has two or three lids (lids) that cover the front and back surfaces of the magnetic tape in order to obtain dustproofness that can withstand outdoor use.

FIG. 4 is a perspective view of a magnetic tape cassette. As shown in the figure, the magnetic tape cassette 50 has a cassette case composed of upper and lower cassette halves 51 and 52, and a magnetic tape 54 is stretched over an opening 53 in front of the cassette case. The magnetic tape 54 is covered with the outer lid 60, the top lid 70, and the inner lid 80 when not in use.

FIG. 5 is an exploded perspective view of a lid portion.
The outer lid 60 has an outer lid portion 61 covering the front surface of the magnetic tape stretched over the opening, and side plate portions 62 provided at both ends of the outer lid portion 61 and covering both front portions of the upper and lower cassette halves. are doing. Each side plate 62
A fulcrum pin 63 is rotatably engaged with a notch (not shown) provided on both front side surfaces of the upper cassette half. Also, the outer lid portion 61
Has a protruding portion 61a that protrudes toward the top lid 70 from the end of the side plate portion 62 inside the side plate portion 62. Pin holes 64 are provided at both ends of the protruding portion 61a.

The top lid 70 covers a top edge of the magnetic tape stretched over the opening, and side plate portions 72 provided at both ends of the top lid portion 71 and covering both front sides of the upper cassette half. And Each side plate 7
On the inner front side (outer lid side), a connection pin 7 rotatably engaged with the pin hole 64 of the outer lid 60 and connecting the top lid 70 to the outer lid 60.
3 are protruded. A slide pin 74 (see FIG. 6) slidably engaged with a guide groove 55 (see FIG. 6) provided on both front sides of the upper cassette half is provided on the rear side inside each side plate portion 72. Have been.

The inner lid 80 has an inner lid portion 81 that covers the back surface of the magnetic tape stretched over the opening, and pin holes of the top lid 70 are formed at both upper ends (top lid side) of the inner lid portion 81. 75 (see FIG. 6), a connecting pin 82 rotatably engaged and connecting the inner lid 80 to the top lid 70 is projected. A slide pin 83 slidably engaged with the guide groove 56 (see FIG. 6) of the lower cassette half is provided on both side surfaces of the lower end of the inner lid portion 81 so as to protrude.

FIG. 6 shows a state in which the outer lid 60, the top lid 70 and the inner lid 80 are closed.
FIG. 2 shows a schematic sectional view of the front of a magnetic tape cassette 50. As described above, the magnetic tape 54 is used when the three lids 6 are not used.
0, 70, 80 to protect from dust and the like. In this state, the locations visible from the outside of each of the lids 60, 70, 80 (for example, the outer surface of the outer lid portion 61, the outer surface of the side plate portion 62, etc.)
In order to obtain the same appearance as 1, 52, it is formed on the embossed surface.

Next, a mold for molding the outer lid 60 will be described. As shown in FIG. 7, in a mold 90 for molding the outer lid 60, a cavity 95 filled with a molding material is provided by a fixed mold 91 and a plurality of slide cores 92, 93, 94. Of these, the molding surfaces of the slide cores 92 and 93 on the outer surface side of the outer lid are subjected to a graining process to form a grained surface.

[0009]

In order to form a complicated shape like the outer lid mold 90 described above,
In a mold having a plurality of slide cores, when the mold is opened and the mold is closed, there may be places where the slide cores are in sliding contact with each other, or where the slide core and the mold main body are in sliding contact. In the outer lid mold 90 described above, for example, a slide core 92 and a slide core 93 are provided.
And there were places that slid in contact with each other. By the way, since the surfaces of the slide cores 92 and 93 are formed in a textured surface, the surface has a high coefficient of friction, and in such a sliding contact portion, there is a tendency that those mold members are worn out early. Was. When the mold member is worn, there is a problem that the resin flows out from the worn portion to form burrs and the like.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the abrasion due to sliding contact between mold members such as a slide core and a mold main body, and to prolong the mold life for injection molding. To provide a mold.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide a mold body comprising a fixed mold and a movable mold, and a slide core, wherein the mold body and the slide core are moved from a grain surface. In the injection mold having a molding surface, when the slide core slides on an extension surface of the molding surface of the mold main body or another slide core,
At least one of the sliding surfaces is formed as a smooth surface by an injection molding die.

Here, as the smooth surface, a mold member surface or the like that has not been subjected to graining can be used. Further, the smooth surface may be provided on both of the contacting mold members, or may be provided on only one of them. When the slide core slides on the extension surface of the molding surface of the other mold member, for example, when the slide core moves toward the mold clamping completion position at the time of mold clamping, the molding surface formed of the embossed surface Means sliding on a portion other than the molding surface of another slide core having
According to the injection molding die having such a configuration, abrasion due to sliding contact between the die members such as the slide core and the die main body is small, and the life of the die can be extended.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the members and the like already described are denoted by the same reference numerals or corresponding reference numerals in the drawings to simplify or omit the description.

FIG. 1 is a perspective view showing a main part of a first embodiment of the present invention. This injection molding die 10 is shown in FIG.
It is for forming the outer lid 60 surrounded by a two-dot chain line, and includes slide cores 12 and 13. The slide core 12 on the right side in the drawing has a flat surface portion 12 a that is a forming surface of the outer lid portion 61 and a curved portion 12 b that is a forming surface of the protruding portion 61 a of the outer lid portion 60. The surfaces of the flat portion 12a and the curved portion 12b are both formed into a textured surface.

The slide core 13 on the left side in the figure is provided with a female mold 13b capable of forming the side plate portion 62 by flowing a molding material into a front flat portion 13a. Female mold 13
The inside of b is formed on a textured surface. The outer lid 6 is provided on the upper side of the female mold 13b in the drawing on the side of the slide core 12.
A substantially cylindrical male die 13d for forming a pin hole 64 at an end of the zero protruding portion 61a is provided.

The slide core 12 is a slide core 1
2, a smooth surface (non-textured surface) 12c is formed in a portion (extended surface of the molding surface 12b) of the slide core 13 in sliding contact with the male die 13d at the time of opening and closing the mold. A substantially cylindrical male mold 1 of the slide core 13 is also provided.
In 3d, a smooth surface (a surface not subjected to graining) 13c is formed on the peripheral surface of the male die 13d.

FIG. 2 shows the injection molding die 10 shown in FIG.
FIG. At the time of mold clamping, first, the slide core 12 first reaches a mold clamping completion position indicated by a two-dot chain line in FIG. Thereafter, the slide core 13 moves, and the smooth surface 13c of the slide core 13 slidably contacts the smooth surface 12c of the slide core 12, and as shown in FIG. I do.

According to the injection molding die having such a configuration, the sliding surfaces of the slide core 12 and the slide core 13 are both formed as smooth surfaces. No abrasion occurs on the sliding contact surface. Therefore, the mold life can be extended.

The present invention is not limited to the above-described embodiment, and can be appropriately modified or changed. For example, in the above-described embodiment, the injection molding die for molding the outer lid of the magnetic tape cassette is provided with a smooth surface. However, various injection molding dies for molding a resin molded product such as a magnetic tape cassette are used. It is possible to apply the technical idea of the present invention to a mold.

[0019]

According to the injection mold of the present invention, when the slide core slides on the extension surface of the molding surface of the mold main body or another slide core, the sliding surface is formed as a smooth surface. Have been. Therefore, wear due to contact between the mold members such as the slide core and the mold main body is small, and the mold life can be extended.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a plan view of the injection mold of FIG. 1;

FIG. 3 is a view showing a state at the time of completion of mold clamping of the injection molding die in FIG. 2;

FIG. 4 is a perspective view of a magnetic tape cassette.

FIG. 5 is an exploded perspective view of a lid part.

FIG. 6 is a sectional view of the magnetic tape cassette when the lid is closed.

FIG. 7 is a view showing an injection molding die for molding the outer lid in FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 Mold for injection molding 12 Slide core 12a Flat portion 12b Curved portion 12c Smooth surface 13 Slide core 13a Flat portion 13b Female mold 13c Smooth surface 13d Male mold

Claims (1)

[Claims] 1. An injection mold comprising a mold main body composed of a fixed mold and a movable mold, and a slide core, wherein the mold main body and the slide core have a molding surface formed of a textured surface. In the mold, at least one of the sliding surfaces when the slide core slides on the extension surface of the molding surface of the mold main body or another slide core is formed as a smooth surface. A mold for injection molding, characterized in that: