JPH042468Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a tape cassette case for video, audio, etc., and particularly to a guard panel that covers an opening provided for making contact between a magnetic tape and a head.

Conventional technology Traditionally, tape cassettes for video tapes, etc., were provided with guard panels at the openings to cover the openings when not in use to protect the tapes, to prevent dirt and dust from entering through the openings, and to prevent dirt and dust from entering through the openings. Be careful not to accidentally touch the tape and damage it or leave marks on it. When this happens, signal errors occur, resulting in distorted images on video tapes and skipping on audio tapes. FIG. 2 is an external perspective view of such a videotape cassette. 3 is a perspective view mainly showing the back side of the guard panel shown in FIG. 2. FIG. FIG. 4 is an enlarged sectional view of the guard panel shown in FIG. 3, in which figure A is a sectional view taken along the -X line, and figure B is a sectional view taken along the Y-Y line. In the figure, 10
is the upper half, 12 is the side plate of the upper half, 14,1
4a, 14b are windows provided in the upper half, 16
is the lower half, and the upper and lower halves are combined to store tape or the like (not shown). Reference numeral 18 denotes a guard panel, and upper and lower halves 1 are provided to make contact between the tape and the head (not shown).
It covers the openings (not shown) at 0 and 16. The guard panel 18 is rotatably supported by the upper half 10, etc., and is kept closed by covering the opening when not in use, but when the cassette is attached to a deck or the like (not shown) during use, the lock is released. The guard panel 18 rotates to open the opening. 20
2 is an elongated front plate of the guard panel 18, and 22 is an elongated upper plate thereof, and their respective long sides are joined to form an elongated plate body having a substantially L-shaped cross section. 2
4, 24a, and 24b are side plates that respectively cover both sides of the elongated plate and are orthogonal to both plates 20 and 22. The projecting end 2 of each side plate 24
Support shafts of the guard panel 18, such as cylindrical projections 28, 28a, 28b, protrude from the 6, 26a, 26b. Each of the cylindrical projections 28 is fitted into a shaft insertion hole (not shown) in the side plate 12 or the like near the front corner of the upper half 10. 30
is a recess near the gate (plastic injection port of the mold), and is provided at the joint between the front plate 20 and the front plate 22. At the center of the back side of the top plate 22 corresponding to the recess 30, a recess 32 having a rectangular opening is provided. This recess 3
2 is formed by a convex portion provided on the core of a mold for an injection molding machine. Molten plastic injected from the gate is smoothly injected into the mold in a well-balanced manner due to the presence of the convex portion, and the guard panel 18 is formed.

FIG. 5 is an explanatory view showing the vicinity of the mold for the injection molding machine, and is a view showing the molding process of the guard panel. In the figure, 34 is a movable platen, and 36 is a fixed platen. A mold is attached between both platens 34 and 36. Reference numerals 38, 38a, and 38b designate mounting plates, 40, 40a, and 40b a back plate, 42 a core plate, 44 a cavity plate, 46 a core, 48 a cavity, 50 a molded product, and 52 a gate. In this way, molded product 5
0 is formed when molten plastic enters through the gate 52 via the sprue 51 and fills the space between the core 46 and the cavity 48. Therefore, the core 46 is provided with a convex portion that forms the back side of the molded product 50, and the cavity 48 is provided with a concave portion that forms the front side. To take out the molded product 50, it is left to cool for a few seconds, and then the core plate 42 and cavity plate 44 are separated. Then, the core 46 moves while holding the molded product 50 in close contact with it, so when the mold is completely opened, the ejector plate 56 is moved and the ejector pins 58, which were fixed to the plate 56, are moved.
The molded product 50 is pushed out at 58a and 58b and extracted from the core 46. Usually, a mold is made with the idea of punching out a molded product 50, and the molded product 5 formed inside the mold is
0 is placed so that it can be easily removed without putting any strain on it due to the protrusion of the ejector pin 58.
When protruding the guard panel 18, the back side of the front plate 20 is usually pressed in several places. In addition,
At this time, the cylindrical projections 28, which serve as support shafts, projecting from each side plate 24 of the guard panel 18 have already been opened by the mechanism of the mold at the time of ejection.

Problems to be Solved by the Invention However, since the long sides of the front plate 20 and the top plate 22 of the guard panel 18 are joined to each other and their surfaces are perpendicular to each other, the cavities that come into contact with them are The molding surface of 48 is also bent at right angles, and there is only a slight draft angle. Further, the front surface of the top plate 22 is a glossy surface, and therefore the degree of adhesion to the cavity surface is particularly high. When the mold in such a state is opened, the space between the cavity 48 and the front plate 20 momentarily becomes a vacuum state at the beginning of the mold opening, and the molded product 50 sticks to the cavity 48 and is pulled. As a result, the molded product 50 is pulled into the cavity 48 by the force pulled by the core 46.
Since the tensile force exceeds that, a force that deforms the glossy surface of the top plate 22 is generated. In particular, the side plate 24
The area near the joint deforms in the direction of opening due to the force, causing a crack. Such a top plate 22
The deformation and occurrence of cracks cause problems such as deteriorating the appearance quality of the molded product 50 and reducing its strength.

FIG. 6 is an example diagram showing the deformed state of the guard panel and the position of crack occurrence at the moment the mold is opened.
In the figure, dotted circles 60, 60a, and 60b indicate the vicinity of the crack occurrence position. As is clear from this figure, no deformation occurs in the central portion of the top plate 22, but deformation occurs on both sides thereof. The reason for this is that there is a gate 52 in the center, and a recess 3 with a rectangular opening is formed on the back side of the gate 52.
Since the rectangular convex part of the core 46 enters into the 2 and makes good contact, the holding force of the core 46 increases at that point,
This is because in other places, it sticks to the cavity surface and is pulled.

In order to solve these problems, the present applicant previously proposed, in Utility Application No. 59-144772, to provide at least one recess at a required position on each side from the center of the top plate at a location with a different thickness, such as a recess. I filed an application stating that. It is true that if the top plate has such a structure, the conventional problems will be solved to some extent.
However, even if such a structure is adopted, the shorter the molding cycle, the higher the temperature at which the molded product is taken out due to the nature of plastic, and the easier it is to change its shape. It becomes arch-shaped and is pulled against the cavity surface and rises above the core, making it easier for cracks to occur. It has been found that even when the molding cycle is shortened in this way, the problem still remains unsolved.

The present invention was developed by focusing on these conventional problems, and even though the structure of the top plate of the guard panel was improved to shorten the molding cycle and increase productivity, it still caused problems such as cracks and deformation. To provide a guard panel for a tape cassette which does not cause any damage, improves the appearance quality, and increases strength.

Means for Solving the Problems Means for achieving the above object will be explained below using FIG. 1 and FIG. 7A, which correspond to the embodiment. This tape cassette guard panel has a long and slender plate with a substantially L-shaped cross section and a front plate 62 and a top plate 64, and a guard panel support shaft 70 that extends perpendicularly to both plates and covers the sides of the plate. A side plate 66 is provided. A recess 76a is provided at a predetermined position on the back side of the top plate 64, and at least one inner surface 78 forming the recess 76a is attached to the front surface of any one of the front plate 62, the top plate 64, and the side plate 66, which serves as a reference surface. The inner surface is inclined with respect to the core movement direction when the mold is opened, which is parallel or perpendicular to the side surface.

Function: With the above-described structure, at least one inner surface 78 forming the recess 76a is connected to the front plate 6 serving as a reference surface.
2. When the core is tilted with respect to the direction of core movement when the mold is opened, which is parallel or perpendicular to the front surface of either the top plate 64 or the side plate 66, the core naturally has a recess 76a at a position corresponding to the recess 76a. A convex portion having a shape that fits, ie, an inclined outer surface forming an inclined inner surface 78, is provided. As a result, the top plate 64 comes into close contact with the convex portion of the core at the position of the recess 76a, and the inclined inner surface 78 and the inclined outer surface on the extraction side of the core abut, so that the core holding force increases at that point. Instead, when the mold is opened, a resistance force can be generated between both abutting surfaces to counter the tensile force of the cavity. The generation of such a resistance force increases the force that resists the pull on the cavity surface, making it possible for the core's pull force (sum of holding force and resistance force) on the molded product to exceed the tensile force on the cavity surface. becomes. Therefore, even if the molding cycle is shortened, if the inclination angle θ1 of the inclined inner surface 78 with respect to the core movement direction when the mold is opened is selected, the molded product will be pulled against the cavity surface when the mold is opened, and it will momentarily become arched. This can prevent deformation such as lifting off the core.

Embodiments Hereinafter, main parts of embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a plan view of a guard panel for a tape cassette according to an embodiment of the present invention. Figure 7 shows
FIG. 2 is an enlarged cross-sectional view of the guard panel shown in FIG. 1, in which figure A is a cross-sectional view taken along the line X-X, and figure B is a cross-sectional view taken along the line Y-Y. 8 is a perspective view mainly showing the back side of the guard panel shown in FIG. 1. FIG. Comparing this example with conventional examples (mainly the example shown in Utility Application No. 59-144772), in this example a recess is provided on the back side of the top plate, and the inner surface of the recess is exposed when the mold is opened. In contrast, in the conventional example, a concave portion is provided to make the thickness of the same part of the top plate different from other parts, but in the latter case, the presence of an inclined inner surface is has not been made clear. Therefore, the only difference between the two structures is the presence or absence of an inclined inner surface, and all other corresponding parts are substantially the same. Therefore, in this embodiment, explanations regarding those identical corresponding parts will be omitted by referring to the conventional example. However, this description will be made within the scope of explaining the main parts of this embodiment. In the figure, 62 is a front plate, 64 is a top plate, 66, 66a, 66b are side plates, 68, 68
a, 68b are protrusions of the respective side plates 66, 70,
70a and 70b are guard panel support shafts, 72 is a recess near the gate, and 74 is a truncated pyramid-shaped recess having a rectangular opening provided at the center of the back side corresponding to the recess 72. 76, 76a, 76b are located at required positions on both sides from the center of the top plate 64.
These are wedge-shaped recesses each having a rectangular opening, for example. Each of the recesses 76 is located at a distance La and a distance Lb from the center of the back surface of the top plate 64 toward each end in the longitudinal direction on both sides, and each of the openings has a length in the longitudinal direction. Saha
c1, the width in the short direction is the distance from the back side of the front plate 62
It starts at a distance d1 and has a length e1. Moreover, the depth of each is f1. Note that by reducing the distance d1 so that these recesses 76 are close to the front plate 62, it is possible to prevent sink marks (dents that occur when plastic is cooled and solidified) that tend to occur on the surface of the molded product. 78 is the recess 7
6, and is an inclined inner surface that is inclined at an angle θ1 with respect to the front surface of the upper plate 64, which serves as a reference surface. Note that the other inner surfaces on both sides are parallel to the front surface of the side plate 66, which serves as a reference surface.

In order to form such an inclined inner surface 78, naturally, on the core, a shape that fits into the wedge-shaped recess 76, that is, an inclined inner surface 7 is formed at a location corresponding to the recess 76.
A wedge-shaped convex portion having an inclined outer surface for forming an 8-shape is provided. As a result, the top plate 64
Since the wedge-shaped concave portion 76 is in close contact with the wedge-shaped convex portion of the core, and the inclined inner surface 78 and the inclined outer surface on the withdrawal side of the core are in contact with each other, the holding force of the core is increased at that location. Furthermore, when the mold is opened, if the core is moved in a direction parallel to the front surface of the top plate 64 serving as a reference surface, a resistance force opposing the tensile force of the cavity is generated between both contact surfaces. Therefore, the 9th A
As shown in the figure, the core 79 moves in the direction of the arrow while keeping the molded product 81, which is a guard panel, in close contact with the molded product 81 and separates it from the cavity 83. In addition, 84
is a wedge-shaped convex portion of the core 79. Thereafter, when the mold is completely opened, the molded product 81 is ejected in the direction of the arrow by the ejector pin 85 and extracted from the core 79, as shown in FIG. 9B. In order to increase the magnitude of this resistance force, the inclination angle θ1 may be increased. In addition, in order to make the pulling force of the core against the molded product (sum of holding force and resistance force) exceed the tensile force of the cavity surface, and to keep the molded product in close contact with the core when opening the mold, it is necessary to It is preferable to select the angle θ1 to be around 30°. Furthermore, in order to deal with the abrasion that occurs when the molded product is extracted from the mold, it is sufficient to provide a radius near the corners of both the inclined inner surface 78 and the inclined outer surface. Furthermore, in order to ensure the core holding force, the height of the wedge-shaped protrusion 84, ie, the depth f1 of the wedge-shaped recess 76, may be selected. When such a wedge-shaped recess 76 is provided in the top plate 64, the molding cycle can be shortened and productivity can be increased.

Moreover, if the injection molding machine is operated continuously for a long time (about 48 hours), the wedge-shaped recess 76 provided in the top plate 64 deforms, making it unstable to extract the molded product. This is caused by the fact that the wedge-shaped protrusion 84 of the core repeatedly holds the hot molded product, so an excessive load is applied to the wedge-shaped protrusion 84, causing that portion to deform. Therefore, in order to reduce the burden on the wedge-shaped protrusion 84 of the core,
A recess having a rectangular opening in the center of the upper plate 64 is utilized, and a part of the upper inner surface forming the recess is formed as an inclined inner surface 80, so that the entire recess 74 has a truncated pyramid shape. Comparing this truncated pyramid-shaped recess 74 and the wedge-shaped recess 76 described above, only the width in the short direction of the opening is different, e2 < e1, but both inclined inner surfaces 78 and 80 are inclined in the direction of movement of the core 79. All other corresponding parts are substantially the same, such that the depths of the recesses 74, 76 are similarly sloped. Note that, of course, the values of the corresponding portions can also be made different between the two. When such recesses 74 and 76 are sequentially provided at equally divided positions along the longitudinal direction of the top plate 64, the holding force and the resistance force are increased by the respective protrusions that fit into the recesses 74 and 76 of the core. Since it is distributed almost evenly, it is possible to counteract the pull caused by the cavity surface in a suitable manner.

In this embodiment, recesses 74, 7 provided in the top plate 64
Upper inner surfaces 78, 80 on the core drawing side for forming 6
As shown in FIG. Recess 87 provided in 86
A side plate (not shown) that serves as a reference surface with both inner surfaces 88, 88a, and 88b forming inclined inner surfaces, respectively.
The recesses 87 are each inclined at an inclination angle θ2 with respect to the front surface of the front plate 89 so that the width of the recess 87 decreases with respect to the moving direction of the core shown by the arrow, and the distance between the opposing inclined inner surfaces is adjusted from the front plate 89 to the required position. You can also make it narrower the further apart you are. Moreover, each inner surface forming the recess can be made into an inclined inner surface using the front surface of the front plate as a reference surface, or a plurality of inner surfaces forming the recess can be made into inclined inner surfaces at the same time. Furthermore, the position, shape, size, etc. of the recessed portion having the inclined inner surface provided on the back side of the top plate can be appropriately selected in practice.

Effects of the invention According to the invention described above, a recess is provided at a predetermined position on the back side of the top plate, and at least one inner surface forming the recess is attached to one of the front plate, the top plate, and the side plate serving as a reference surface. Since the inclined inner surface is inclined with respect to the core movement direction when the mold is opened, which is parallel or perpendicular to the front surface of the mold, the holding force of the core is increased at the point where it comes into contact with the inclined inner surface, and the resistance against the tensile force of the cavity is increased. can generate force. Therefore,
Even if the molding cycle is shortened and productivity is increased, the guard panel does not suffer from cracks or deformation, and it is possible to improve the appearance quality and increase the strength.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a guard panel for a tape cassette according to an embodiment of the present invention. Figure 2 shows
FIG. 1 is a perspective view of a conventional video tape cassette. 3 is a perspective view mainly showing the back side of the guard panel shown in FIG. 2. FIG. FIG. 4 is an enlarged sectional view of the guard panel shown in FIG. 3, in which figure A is a sectional view taken along the line X-X, and figure B is a sectional view taken along the line Y-Y. FIG. 5 is an explanatory view showing the vicinity of the mold for the injection molding machine, and is a view showing the molding process of the guard panel. FIG. 6 is an example diagram showing the deformed state of the guard panel and the position of crack occurrence at the moment the mold is opened. FIG. 7 is an enlarged sectional view of the guard panel shown in FIG.
The figure is a sectional view taken along the line YY. 8 is a perspective view mainly showing the back side of the guard panel shown in FIG. 1. FIG. FIG. 9 is a diagram showing the process of extracting a guard panel, which is a molded product, from a mold for an injection molding machine, and is an enlarged sectional view taken along the Z-Z line in FIG. 5. 10th
The figure shows a part of the back side of a guard panel for a tape cassette according to another embodiment of the present invention. 62, 89... Front plate, 64, 86... Top plate, 66... Side plate, 74, 76, 87... Recessed portion, 78, 88... Inclined inner surface, 79... Core.

Claims (1)

[Claims for Utility Model Registration] (1) An elongated plate having a substantially L-shaped cross section and having a front plate 62, 89 and a top plate 64, 86, and a plate extending perpendicularly to both plates, covering the side surface of the plate. In the tape cassette guard panel including a side plate 66 from which a guard panel support shaft 70 projects, recesses 7 are formed at predetermined positions on the back sides of the upper plates 64 and 86.
4, 76, 87 are provided, and the recesses 74, 76,
at least one inner surface 78, 80 forming 87;
88 is an inclined inner surface that is inclined with respect to the direction of core movement when the mold is opened, which is parallel or perpendicular to the front surface of any of the front plates 62, 89, top plates 64, 86, and side plates 66, which serve as reference surfaces. A guard panel for tape cassettes characterized by: (2) an upper inner surface 78 forming the recesses 74 and 76;
Top plate 64 with 80 as an inclined inner surface and serving as a reference surface
A guard panel for a tape cassette according to claim 1, wherein the depth of the recesses 74 and 76 increases as the recesses 74 and 76 approach the front plate 62 to a required position. (3) The inner surfaces 88 on both sides forming the recess 87 are each made to be inclined inner surfaces and are inclined with respect to the front surface of the side plate serving as a reference surface, and the distance between the opposing inclined inner surfaces is made narrower as the distance from the front plate 89 increases to a desired position. Claim 1 for utility model registration characterized by:
Guard panel for tape cassettes as described in section.