JPH0766648B2 - Molding method of front cover for video tape cassette - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape cassette used in a video tape recorder (hereinafter referred to as a VTR), and in particular, a front cover rotatably mounted on a deck insertion side of a cassette body. On how to do.

[0002]

2. Description of the Related Art As shown in FIG. 4, a video tape cassette used in a home VTR has a pair of winding reels in a cassette body 3 which is composed of an upper half 1 and a lower half 2. Is rotatably housed, and the front cover 4 covers the front surface of the video tape unwound from the winding reels to the VTR insertion side surface of the cassette body 3.

As shown in the perspective view of FIG. 5, the front cover 4 has a belt-shaped front plate 4a for covering the VTR insertion side of the cassette body 3 and one side edge of the front plate 4a over the entire length. A narrow top plate 4b protrudingly provided, and a front plate 4a and a top plate 4b.
Guide recesses 3a, 3a provided on the outer surfaces of the front portions of both side walls of the cassette body 3 so as to project from both ends of the cassette 4 in the same direction as the top plate 4b.
And a pair of side plates 4c and 4d mounted on the
A pair of support shafts 4e and 4f projecting from c and 4d facing each other
And the front cover 4 has support shafts 4e, 4f.
Is pivotally supported by the guide concave portions 3a, 3a, and is rotatably attached to the front portion of the cassette body 3.

The one support shaft 4e is formed longer than the other support shaft 4f, and is provided with a small-diameter spring locking pin 4g protruding parallel to the front plate 4a. One end of a coil spring (not shown) is engaged with the spring locking pin 4g, and the front cover 4 is constantly biased in the closing direction by the elastic force of the coil spring to cover the VTR insertion side surface of the cassette body 3. To protect the videotape.

At the lower edge of the inner surface of the front plate 4a, three notches 4h and a plurality of guide ribs 4i are provided, and when the front cover 4 covers the VTR insertion side surface of the cassette body 3, these are formed. The guide rib 4i of FIG. 3 prevents the slack of the video tape.

6 to 9 show a molding state of the front cover 4, and a molding die 5 for molding the cover 4.
Is composed of six fixed dies, a fixed die 6 and a movable die 7, and two sets of four slide cores 8, 9, 10, 11. Since the periphery of the side plates 4c and 4d including the support shafts 4e and 4f cannot be punched by the fixed and movable dies 6 and 7,
The side plate 4c side having the spring locking pin 4g is the fixed die 6 and the slide cores 8 and 9, and the other side plate 4d side is the fixed die 6 and the slide cores 10 and 11 as shown in FIG.
And the movable mold 7 and the other parts except the periphery of the side plates 4c and 4d.
Formed by and.

In the movable mold 7 shown in FIG. 8, a fixed mold 6 and a cavity 12 (see FIG. 6) for molding products are defined.
An individual molding space portion 13 is provided. The molding space 13 is provided so that the inner and outer surfaces of the front plate 4a of the front cover 4 face the fixed and movable molds 6 and 7, and the guide groove 14 is continuous with the both ends of the space 13 in the intersecting direction. The slide cores 8, 9, 10, 11 described above are slidably arranged.

After molding the front cover 4 in the cavity 12 of the molding die 5 (FIG. 6), the movable die 7 and the slide cores 8 and 9 are formed on the inner and outer surfaces of the front plate 4a with respect to the fixed die 6. The mold is integrally released in the opposite arrow A direction (FIG. 7). Further, the respective slide cores 89, 10 and 11 are separated from each other in the direction of the arrow B orthogonal thereto, and the outer slide cores come into contact with the stopper 15 and the inner slide cores come into contact with each other to stop. (FIGS. 8 and 9).

[0009]

In the above-mentioned molding, since a fixed and movable mold and two sets of slide cores are required, the number of operation steps is long and the molding time is long, and the mold is expensive and complicated. ing. Further, since the movable mold requires a space for moving the slide core, only a small number of products can be taken in one molding, resulting in poor productivity.

Therefore, the present inventors prevent the slack of the video tape from being substantially prevented by the reel lock lever which regulates the rotation of the winding reel when it is not used, so that the guide rib of the front cover has no slack prevention effect. Focusing attention, by omitting this guide rib from the front cover, the slide core is omitted from the molding die, and it is an object of the present invention to provide a front cover molding method for a video tape cassette in which productivity is improved by molding. To do.

[0011]

In order to achieve the above object, the present invention is provided with a front plate that covers the VTR insertion side surface of the cassette body and one side edge of the front plate that projects over the entire length. The top plate, the front plate and the pair of side plates protruding from both ends of the front plate in the same direction as the top plate, and the side plates arranged outside the side wall of the cassette body, and the pair of side plates protruding opposite to each other. A method of forming a front cover for a video tape cassette, comprising: a pivot for pivoting on a side wall of the pivot and a spring locking pin protruding from one of the pivots in parallel with the front plate. The molding die is a two-divided die of a fixed die and a movable die that are separated from each other in parallel with the inner and outer surfaces of the front plate, and the anti-spring locking pin side of the spindle is a fixed die.
The spring locking pin side of the support shaft and the spring locking pin as a whole are formed by a movable mold, and the inner surfaces of the front plate and the top plate are formed by the movable mold over the entire length. After the front cover is molded, the movable mold is released along the inner surface of the front plate.

[0012]

According to the method of the present invention, the mold release after molding can be done in one direction. Therefore, the molding of the peripheral portion of the side plate is carried by the fixed mold and the movable mold, and by separating the movable mold in the above-mentioned one direction,
It is possible to omit the slide core.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

1 is a sectional view showing a molding state of the front cover 20, FIG. 2 is a plan view of the movable mold 23, and FIG. 3 is a perspective view of the front cover 20 molded by the molding mold 21 of this embodiment. The reference numerals used in the conventional example will be referred to in describing the present embodiment.

The front cover 20 includes a front plate 20a and a top plate 20b which cover the VTR insertion side of the cassette body 3 shown in FIG. 4, side plates 20c and 20d mounted in the guide recesses 3b and 3b of the cassette 3, respectively. Long and short support shafts 20e and 20f projecting opposite to the side plates 20c and 20d are provided in a shape similar to that of the conventional example. Also, the front plate 20
A notch 20h is provided in a, and a spring retaining pin 20g is similarly provided in the long support shaft 20e, except that the guide rib 4i in the front cover 4 of the conventional example is omitted.

A molding die 21 for molding the front cover 20 is composed of two divided dies, a fixed die 22 and a movable die 23. The movable die 23 shown in FIG. 2 has the same size as the movable die 7 of the conventional example, and the movable die 23 has eight cavities 24 (see FIG. 1) for forming the product together with the fixed die 22. The molding space portions 25 are provided, and each of the molding space portions 25 is formed such that the inner and outer surfaces of the top plate 21b of the front cover 20 face the fixed and movable molds 22 and 23. Therefore, the fixed mold 22 and the movable mold 23 face the front cover 20 in a direction intersecting with the fixed and movable molds 6 and 7 of the conventional example, and the movable mold 23 after molding has a drawing direction. The direction of arrow C is parallel to the inner and outer surfaces of the front plate 20a and the spring locking pin 20g.

The front cover 20 is formed by filling the above-mentioned cavity 24 defined by the fixed die 22 and the movable die 23 with the molten material. In the structure of the front cover 20, the inner surfaces of the front plate 20a and the top plate 20b are formed by the movable mold 23 along their entire length. In addition, the support shafts 20e, 2
At 0f, the radial lines of the support shafts 20e and 20f, which are orthogonal to the front plate 20a, indicate the joint surface 26 of the fixed die 22 and the movable die 23.
The support shafts 20e and 20f are attached to the spring locking pin 2
The opposite half of 0 g is formed by the fixed mold 22, and the half on the side of the spring locking pin 20 g and the spring locking pin 20.
The entire g is formed by the movable mold 23. And
After the molten metal in the cavity 24 has cooled, the movable die 23 is released in the direction of arrow C along the inner surface of the front plate 20a, and the front cover 20 which is the work is removed.

As described above, in the present embodiment, the entire front cover 20 is molded by the two divided molds, the fixed mold 22 and the movable mold 23, so that the slide core conventionally used is not necessary. As a result, the number of working steps is reduced and the molding time can be shortened. Moreover, since the number of divided molds is small, the mold cost can be kept low. Furthermore, since the overall structure of the mold is simple, it is easy to maintain,
Moreover, there are few failures even after long-term use.

Further, since the movable die 23 does not require a space for arranging or moving the slide core, even if the die 21 has the same size as the conventional one, it is possible to take eight products by one pressing operation. Therefore, the productivity can be improved in combination with the shortening of the molding time. Furthermore,
In the front cover 20 molded in this way, the ribs 4i having the conventional shape are omitted, so that the material can be saved and the weight can be reduced.

[0020]

As described above, according to the method of the present invention,
The conventionally used slide core is no longer required, and the number of working steps is reduced, and the molding time can be shortened. In addition, since the number of forming dies is small, the die cost can be kept low. Furthermore, since the configuration of the entire molding die is simple,
It is easy to maintain and there are few failures even after long-term use. Further, since the molding die does not require a space for arranging or moving the slide core, a large number of products can be taken by one pressing operation even if the molding die has the same size as the conventional one, and the molding time can be shortened. This can be combined with the improvement of productivity to improve productivity. Further, in the front cover formed by the method of the present invention, the conventional rib shape is eliminated, so that the material can be saved and the weight can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a molding die showing an embodiment of the present invention.

FIG. 2 is a plan view of a movable type.

FIG. 3 is a perspective view of a front cover molded by the molding die of FIG.

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

FIG. 5 is a perspective view of a conventional front cover.

FIG. 6 is a cross-sectional view showing a molded state of the front cover of FIG.

FIG. 7 is a cross-sectional view showing a released state after molding.

FIG. 8 is a plan view of the movable type.

9 is a sectional view of FIG.

[Explanation of symbols]

3 ... Cassette body, 3a ... Guide recess, 4 ... Front cover, 4a ... Front plate, 4b ... Top plate, 4c, 4d ... Side plate, 4
e, 4f ... Spindle, 4g ... Spring locking pin, 4h ... Notch, 4i ... Guide rib, 5 ... Mold, 6 ... Fixed mold, 7
... Movable type, 8, 9, 10, 11 ... Slide core, 12 ...
Cavity, 13 ... Molding space, 14 ... Guide groove, 15
... stopper, 20 ... front cover, 20a ... front plate, 2
0b ... top plate, 20c, 20d ... side plate, 20e, 20f ...
Support shaft, 20h ... Notch, 20g ... Spring locking pin,
21 ... Mold, 22 ... Fixed mold, 23 ... Movable mold, 24 ... Cavity, 25 ... Mold space provided in the movable mold 23,
26 ... Joining surface of fixed mold 22 and movable mold 23, A ... Mold releasing direction of movable mold 7 of conventional example, B ... Slide core 8 of conventional example,
Mold release direction of 9, 10, 11 C, movable mold 23 of this embodiment
Mold release direction

Claims (1)

[Claims] 1. A front plate for covering a deck insertion side of a cassette body, a top plate projecting over one side edge of the front plate over the entire length, and a top plate from both ends of the front plate and the top plate. A pair of side plates protruding in the same direction and arranged outside the side wall of the cassette body; A method of molding a front cover for a video tape cassette, comprising: a spring locking pin that projects from one of the shafts in parallel with the front plate, wherein a mold for the front cover is released in parallel with the inner and outer surfaces of the front plate. It is not divided into two types, a fixed type and a movable type, and the side opposite to the spring locking pin of the spindle is a fixed type.
The spring locking pin side of the support shaft and the spring locking pin as a whole are formed by a movable mold, and the inner surfaces of the front plate and the top plate are formed by the movable mold over the entire length. A method of molding a front cover for a video tape cassette, which comprises releasing a movable mold along the inner surface of the front plate after molding the front cover.