JP2884887B2 - Thin-walled two-color molded product and mold device for the molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin two-color molded product used as a tape cassette half and the like and a molding apparatus for molding the same, and more particularly, to a first resin partially overlapped in the thickness direction. The present invention relates to a thin two-color molded product made of the resin No. 2 and a mold device for molding the same.

[0002]

2. Description of the Related Art For example, in an audio cassette tape, a magnetic tape wound around a pair of rotatable hubs is stored in the cassette. This cassette is generally formed by connecting a pair of case-shaped cassette halves, and this cassette half is a resin molded product. And as such a tape cassette half,
In many cases, a thin-walled two-color molded product in which the central portion is a window portion for seeing through the tape diameter and the other portion is opaque is used. Further, in a cassette half made of such a thin two-color molded product, there is a cassette half in which a transparent resin is partially overlapped on the front side of an opaque resin in order to enhance appearance.

Conventionally, in two-color molding of such a cassette half, a mold apparatus as described in, for example, JP-A-63-293023 is used. This mold apparatus includes a movable mold plate forming the back surface (inner surface) of the cassette half, a fixed mold plate forming the front surface (outer surface) of the cassette half, a first movable mold body, and a second movable mold body. I have.
The fixed mold plate forms the surface of the opaque single layer made of only the opaque resin in the entire thickness direction of the surface of the cassette half. The first movable mold body is slidable with respect to the fixed mold plate, and forms a surface of a two-layer portion in which a transparent resin is superposed on the front side of an opaque resin. The second movable mold body is slidable with respect to the first movable mold body, and forms the surface of a transparent layer portion, that is, a window portion, which is entirely made of a transparent resin only in the thickness direction. Both the primary gate for the opaque resin and the secondary gate for the transparent resin are side gates that open to positions on the outer surface of the cassette half. Then, at the time of molding, with the fixed mold plate and the movable mold plate clamped, first, the second movable mold body is abutted against the movable mold plate, and the first movable mold body is brought close to the movable mold plate, A primary cavity is formed, and the primary cavity is filled with an opaque resin from a primary gate. At this time, the secondary gate is closed by the side surface of the first movable body. Then, the second movable mold body is separated from the movable mold plate, and the first movable mold body is slightly separated from the movable mold plate to open the secondary gate and form a secondary cavity. Is filled with transparent resin from the secondary gate. However, in this conventional mold apparatus, since the primary gate and the secondary gate are both opened to the positions that become the outer surfaces of the cassette half, the appearance is improved by the gate marks formed on the outer surface of the cassette half. Spoil.

On the other hand, there is also known a mold device for two-color molding of a cassette half as disclosed in Japanese Patent Application Laid-Open No. 1-241078. This mold apparatus includes a fixed mold that forms the front surface of the cassette half, a fixed slide core that is slidable with respect to the mold, a movable mold that forms the back surface of the cassette half, and a sliding mold that slides with respect to the mold. And a movable movable slide core. The fixed-side mold forms the surface of the single-layer part. The fixed-side slide core forms the surface of the two-layer portion. The movable mold forms the back surface of the opaque one-layer part and the two-layer part. The movable slide core forms the back surface of the transparent layer. The secondary gate for the transparent resin is located in the movable mold and opens at the boundary between the opaque layer and the transparent layer, that is, the window. Also, in order to open the secondary gate at the boundary between the two layers having a substantially uniform thickness,
A secondary gate is opened on the side surface of the protrusion protruding from the movable mold toward the fixed mold. Then, during molding, with the fixed mold and the movable mold closed, first, the movable slide core is abutted against the fixed mold, and the fixed slide core is brought close to the movable mold. hand,
A primary cavity is formed, and the primary cavity is filled with an opaque resin. At this time, the secondary gate is closed by the side surface of the movable slide core. Next, the fixed slide core is separated from the movable mold, and the movable slide core is separated from the fixed mold.
While opening the secondary gate, a secondary cavity is formed, and the secondary cavity is filled with a transparent resin from the secondary gate. According to this mold apparatus, since the gate mark of the secondary gate is formed on the back side of the cassette half and at the boundary between the opaque layer and the transparent layer, it is inconspicuous and the appearance is improved. As described above, since the secondary gate is provided on the convex portion provided on the movable mold, the opaque layer portion on the back side of the cassette half can have a concave portion adjacent to the transparent layer portion by the convex portion. become.

[0005]

As described above, as described above,
In the conventional mold apparatus described in Japanese Patent Application Laid-Open No. 1-241078, in order to provide a gate at the boundary between the opaque layer and the transparent layer on the back side of the cassette half which is a thin two-color molded product,
A secondary gate is provided on the convex portion provided on the movable mold, and a concave portion is formed on the back side of the molded cassette half, but it is preferable that a concave portion is formed on the back side of the cassette half due to circumstances such as the thickness of the cassette half. There may not be. For example, as shown in FIGS. 7 and 8, not the boundary between the opaque monolayer and the transparent monolayer 1, but the two-layer section 2 and the transparent monolayer 1
When it is intended to provide a secondary gate 5 for a transparent resin on the convex portion 4 formed on the movable mold plate 3 near the boundary with the opaque resin in the two-layer portion 2, part
Due to the thickness of 2a, there is a possibility that the secondary gate 5 having a sufficient size cannot be provided in practice. There is no problem if the height of the convex portion 4 is smaller than the thickness of the opaque resin portion 2a as shown by the chain line, but as shown by the solid line, there is no problem.
Is the same as the thickness of the opaque resin portion 2a, and when the convex portion 4 contacts the fixed movable mold member 7 during the formation of the primary cavity 6, the two-layer portion 2 of the molded cassette half is formed.
In appearance, the missing part of the opaque resin portion 2a is visible through the transparent resin portion 2b. 7 and 8, reference numeral 8 denotes a movable-side movable mold member, and reference numeral 9 denotes a secondary cavity.

Therefore, it is conceivable to form a continuous wrap around the transparent single layer on the back side of the opaque resin portion in the two-layer portion, and to open a secondary gate to the wrap around. However, in this case, when injecting the transparent resin into the secondary cavity from the secondary gate, the molten transparent resin entrains the edge of the opaque resin portion of the two-layer portion that has already been solidified, and There is a possibility that the resin melts and flows out.

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and in forming a thin two-color molded product such as a tape cassette half, a two-layer portion having a second resin on the front side of a first resin. When opening the secondary gate to the wraparound portion made of the first resin located on the back side of the first resin in the two-layer portion between the first layer and the one layer portion made of the second resin, It is an object of the present invention to prevent the first resin that has already been solidified by being caught in the second resin flowing out of the gate from flowing out.

[0008]

According to the present invention, there is provided a thin-walled two-color molded article according to the present invention, comprising: a two-layer part in which a first resin and a second resin are overlapped in a thickness direction; A thin-walled two-color molding in which the whole of the direction has a single-layer portion made of only the second resin, and the second resin of this single-layer portion is integrally continuous with the second resin on the front side of the two-layer portion. In the article, a protrusion protruding from the back surface of the two-layer portion is provided at a position adjacent to the two-layer portion on the back surface of the one-layer portion, and the first of the two-layer portion is integrally and continuously connected to the protrusion. It has a wraparound portion made of a second resin located on the back side of the resin.

In addition, the mold apparatus for molding a thin two-color molded article of the present invention comprises a first mold member for forming a surface of a one-layer part and a two-layer part of the thin two-color molded article; A second mold member movable in a direction approaching and separating from the mold member and forming a back surface of the two-layer portion; and a second mold member movable in parallel and independently of the second mold member. A third mold member forming the back surface of the second mold member and a fourth mold member forming a back surface of the convex portion and the wraparound portion which are movable independently and in parallel with the second mold member and the third mold member. And a gate for the second resin is provided at a position of the second mold member that is opened and closed by the fourth mold member.

[0010]

In the thin two-color molded article of the present invention, the first resin portion is molded at the time of molding, and after the first resin is solidified, the second resin portion is molded. When the second resin is poured into the wraparound portion of the secondary cavity, the second resin flows into a position where the protrusion is integrally continuous with the wraparound portion. It flows into the front side of the first resin portion of the layer portion. At that time, since the convex portion is located at a position adjacent to the two-layer portion on the back surface of the one-layer portion and protrudes from the back surface of the two-layer portion, the flow of the second resin from the position serving as the wraparound portion is The first resin portion of the two-layer portion overlapping the wraparound portion is not entangled by passing through the position that becomes the convex portion. This prevents the first resin portion from melting and flowing out.

That is, when the thin two-color molded article is molded by using the molding apparatus of the present invention, first, the second mold member is positioned slightly apart from the first mold member. A third mold member and a fourth mold member are brought into contact with the first mold member to form a primary cavity between the mold members, and the first resin is poured into the primary cavity. At this time, the gate for the second resin in the second mold member is closed by the fourth mold member. Next, after the first resin filled in the primary cavity is solidified, the first mold member is separated from the first resin portion of the two-layer portion, and the third mold is separated from the first mold member. By further separating the members and further separating the fourth mold member, a secondary cavity is formed between the mold members and the solidified first resin, and a gate for the second resin, that is, a secondary cavity is formed. Open the gate. Then, the second resin is poured from the secondary gate into the secondary cavity.
Thus, the first mold member forms the surface of the one-layer portion and the two-layer portion, the second mold member forms the back surface of the two-layer portion, and the third mold member forms the back surface of the one-layer portion. Then, the convex portion and the back surface of the wraparound portion are formed by the fourth mold member. However, when the second resin is injected from the secondary gate, the second resin wraps around the secondary cavity. The first resin portion of the two-layer portion overlapping with the wraparound portion is not entangled by passing from the position to be the portion to the portion to be the convex portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 3 shows a cassette tape. This cassette tape is composed of a magnetic tape 12 wound around a pair of rotatable hubs 11.
It is housed in 13. The cassette 13 includes a pair of case-shaped cassette halves 1 which are thin two-color molded products.
4 and 15 are combined. Each cassette half 1
As shown in FIGS. 1 and 2, reference numerals 4 and 15 denote an opaque layer 16 at the periphery and a transparent layer 17, that is, a window at the center, and a transparent layer.
There is a two-layer part 18 along one side of 17. The opaque layer 16
Is entirely made of, for example, a black opaque resin (first resin) in the thickness direction, and the transparent layer portion 17 is made of a transparent resin (second resin) entirely in the thickness direction. I have.
On the other hand, the two-layer portion 18 is formed by overlapping an opaque resin and a transparent resin in the thickness direction, and there is a transparent resin on the front side of the opaque resin. The opaque resin of the two-layer portion 18 is integrally continuous with the opaque resin of the opaque layer portion 16, and the transparent resin of the two-layer portion 18 is integrally formed with the transparent resin of the transparent layer portion 17. It is continuous. The opaque layer
The surface of 16 is a grained surface, and the surfaces of the transparent single-layer portion 17 and the two-layer portion 18 are glossy surfaces. And
As shown in FIG. 6, at a position adjacent to the two-layer part 18 on the back surface of the transparent single-layer part 17, a projection 19 projecting from the back surface of the two-layer part 18 is formed, A wraparound portion 20 made of a transparent resin and formed on the back side of the opaque resin portion 18a of the two-layer portion 18 is formed integrally and continuously with the convex portion 19. This wraparound portion 20 is
It is even more protruding. In addition, the edge 21 of the opaque resin portion 18a of the two-layer portion 18 located on the front side of the wraparound portion 20
Also slightly project to the back side.

Next, the tape cassette halves 14, 15
The configuration of the molding die apparatus will be described with reference to FIGS. Reference numeral 31 denotes a fixed type, and 32 denotes a movable type. The fixed type 31 and the movable type 32 are movable in the vertical direction in the figure to open and close. The fixed mold 31 includes a fixed mold plate 33 forming the surface of the opaque layer 16 of the cassette halves 14 and 15, and a transparent layer 31.
A fixed-side movable mold member (first mold member) 34 forming the surfaces of the 17 and the two-layer portion 18 is provided. The fixed-side movable mold member 34 moves in the vertical direction in the figure with respect to the fixed-side mold plate 33 by driving a hydraulic cylinder device or the like. That is, the fixed-side movable mold member 34 is
Is moved by a stroke a between a position where the cassette halves 14 and 15 protrude by about half the thickness of the cassette halves 14 and 15. The movable mold 32 includes a movable mold plate (second mold member) 35 forming the back surface of the opaque single layer portion 16 and the two-layer portion 18 and a first movable mold plate forming the back surface of the transparent single layer portion 17. Side movable mold member (third mold member) 36 and convex portion 19
And a second movable-side movable mold member (a fourth mold member) 37 that forms the back surface of the wraparound portion 20. The movable mold plate 35 moves in the vertical direction in the drawing, that is, the direction in which the movable mold plate 35 approaches and separates from the fixed mold 31. The first movable-side movable mold member 36 is moved in the vertical direction in the drawing with respect to the movable-side mold plate 35 by driving a hydraulic cylinder device or the like. That is, the first movable side movable mold member 36
Moves by a stroke b between a position flush with the movable mold plate 35 and a position protruding about half the thickness of the cassette halves 14 and 15. This b is a
Is almost equal to Further, the second movable side movable mold member
37 moves vertically in the figure relative to the movable mold plate 35 independently of the first movable mold member 36 by driving a hydraulic cylinder device or the like. That is, the second movable-side movable mold member 37 moves by a stroke c between the slightly retracted position and the position protruding about half the thickness of the cassette halves 14 and 15 with respect to the movable-side mold plate 35. Is what you do. This c is larger than the a and b. Although not shown, the primary gate for the opaque resin is opened as a side gate or the like at a position corresponding to the outer side surfaces of the cassette halves 14 and 15 in the fixed mold plate 33. On the other hand, the secondary gate 38 for the transparent resin is
The opening is opened at the side position opened and closed by the second movable side movable mold member 37 in FIG. The secondary gate 38 is
The nozzle of the injection molding machine connected to the fixed mold 31 is connected to the nozzle of the injection molding machine via a runner 39 communicating from the fixed mold 31 to the movable mold 32 during mold clamping.

Next, the operation of the above configuration will be described. When the tape cassette halves 14 and 15 are formed, the fixed mold plate 33 and the movable mold plate 35 are brought into contact with each other as shown in the figure, and the fixed mold 31 and the movable mold 32 are clamped. Then, as shown by a solid line in FIG. 4 and as shown in FIG. 5, first, the fixed-side movable mold member 34 is lowered with respect to the fixed-side mold plate 33 as shown in FIG. The movable mold members 36 and 37 are raised in the figure, and the fixed-side movable mold member 34 and both movable-side movable mold members 36 and 37 abut against each other. In this state, the fixed-side movable mold member 34 is
It is located slightly away from 35. Also, the secondary gate 38
Is closed by the side surface of the second movable side movable mold member 37. Thus, the mold plates 33, 35 and the movable mold members 34,
A primary cavity 41 is formed between 36 and 37. Then, an opaque resin melted from the primary gate is poured into the primary cavity 41. Thus, first, cassette half 14,
The opaque resin portion 18a of the opaque single layer portion 16 and the two-layer portion 18 in 15 is molded (primary molding). Then, after the opaque resin filled in the primary cavity 41 is solidified,
As shown in FIG. 4 by a chain line and as shown in FIG.
, The fixed movable mold member 34 is raised in the figure, and both movable movable mold members 36 and 37 are moved relative to the movable mold plate 35.
Is lowered as shown. The second movable side movable mold member 37
Is moved down in the figure to be larger than the first movable-side movable mold member 36. In this manner, the fixed movable mold member 34 is
From the opaque resin portion 18a, the fixed-side movable mold member 34 and the two movable-side movable mold members 36 and 37 are separated from each other, and the second movable-side movable mold member 37 is moved to the first movable side. By positioning it lower than the side movable mold member 36,
The secondary gate 38 is opened, and the secondary cavity 42 is formed between the movable side mold plate 35, the movable mold members 34, 36, 37 and the opaque resin solidified in the primary cavity 41. Then, the transparent resin melted from the secondary gate 38 is poured into the secondary cavity 42. Thus, the cassette half
The transparent resin portions 18b of the transparent single layer portion 17 and the double layer portion 18 in 14 and 15 are molded (secondary molding). Further, after the transparent resin filled in the secondary cavity 42 is solidified, the fixed mold 31 and the movable mold 32 are opened, and the molded cassette halves 14 and 15 are taken out.

In the secondary molding, when the molten transparent resin is injected from the secondary gate 38, the transparent resin first flows into the secondary cavity 42 at a position where the wraparound portion 20 is formed. Then, it flows into the position to become the transparent layer portion 17 and the position to become the transparent resin portion 18b of the two-layer portion 18 via the position to become the convex portion 19. At that time, the flow of the transparent resin from the position that becomes the wraparound portion 20 is a position adjacent to the two-layer portion 18 on the back surface of the transparent single-layer portion 17 and protrudes from the back surface of the two-layer portion 18. The two-layer part 18 overlapping the wraparound part 20 by passing through the position
The edge 21 of the opaque resin portion 18a is largely bypassed, and the edge 21 is not involved. Thereby, this edge 21
In this case, the opaque resin that has already been solidified is prevented from melting and flowing out together with the transparent resin. Thus,
High quality cassette halves 14 and 15 without molding defects can be obtained. The above is because, on the mold configuration, apart from the first movable-side movable mold member 36 that forms the back surface of the transparent layer 17, the projection 19 is formed at a position facing the secondary gate 38. This is made possible by providing the second movable-side movable mold member 37.

According to the structure of the embodiment, the gate trace of the secondary gate 38 is formed by the opaque resin portion 18a of the two-layer portion 18.
The tape cassette 13 is extremely inconspicuous, and the appearance of the tape cassette 13 is improved. Further, since the wraparound portion 20 made of a transparent resin is provided on the back side of the opaque resin portion 18a on the back side of the two-layer portion 18, the joining state between the opaque resin and the transparent resin in the cassette halves 14 and 15 is further strengthened. It becomes something. Further, the convex portion 19 and the wraparound portion 20 also reinforce the cassette halves 14 and 15 themselves.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example,
The arrangement of the opaque single layer, the transparent single layer, and the two-layer part in the tape cassette half, which is a thin two-color molded product, is not limited to the above embodiment. Further, the combination of the first resin and the second resin is not limited to the opaque black resin and the transparent resin. Further, the present invention can be applied to a thin two-color molded product other than the audio tape cassette half.

[0018]

According to the thin two-color molded product of the present invention, in the case where the second resin of one layer is integrally continuous with the second resin on the front side of the two-layer part, the back surface of the one layer is formed. In the position adjacent to the two-layer portion in the above, while having a protruding portion projecting from the back surface of the two-layer portion, the second portion located on the back side of the first resin of the two-layer portion integrally and continuously with the protruding portion By having the wraparound portion made of resin, when molding the second resin portion subsequent to the first resin portion, when the second resin is poured into a position to be a wraparound portion in the secondary cavity in the mold, The flow of the second resin does not involve the first resin portion of the two-layer portion overlapping the wraparound portion by passing through the position that becomes the convex portion, and therefore, the first resin portion melts and flows out. Can be prevented, and molding defects can be prevented.

That is, as in the mold apparatus for molding a thin two-color molded article of the present invention, the first mold member forming the surfaces of the one-layer part and the two-layer part and the back surface of the two-layer part are formed. In addition to the second mold member and the third mold member that is movable with respect to the second mold member and forms the back surface of the first layer,
A fourth mold member movable with respect to the second mold member and the third mold member and forming a back surface of the convex portion and the wraparound portion; and a fourth mold member in the second mold member. By providing a gate for the second resin at a position opened and closed by the mold member, at the time of secondary molding, that is, at the time of molding of the second resin portion, the flow of the second resin overlaps with the wraparound portion. The first resin portion is not involved, so that it is possible to prevent the first resin portion from melting and flowing out.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tape cassette half showing an embodiment of a thin two-color molded product of the present invention.

FIG. 2 is a perspective view of the tape cassette half.

FIG. 3 is a perspective view of the same cassette tape.

FIG. 4 is a cross-sectional view showing one embodiment of a mold apparatus for molding a thin two-color molded article of the present invention.

FIG. 5 is a cross-sectional view of the vicinity of a secondary gate during primary molding.

FIG. 6 is a cross-sectional view of the vicinity of a secondary gate during secondary molding.

FIG. 7 shows an example of a mold apparatus for molding a tape cassette half composed of a thin two-color molded article,
FIG. 3 is a cross-sectional view near a secondary gate during primary molding.

FIG. 8 is a cross-sectional view of the vicinity of a secondary gate during secondary molding.

[Explanation of symbols]

 14, 15 Tape cassette half (thin-wall two-color molded product) 17 Transparent single-layer part (single-layer part) 18 Two-layer part 19 Convex part 20 Wrap-around part 34 Fixed-side movable mold member (first mold member) 35 Movable mold Plate (second mold member) 36 First movable-side movable mold member (third mold member) 37 Second movable-side movable mold member (fourth mold member) 38 Secondary gate ( Gate for the second resin)

Claims (2)

(57) [Claims] 1. A two-layer part in which a first resin and a second resin overlap in a thickness direction, and a one-layer part which is entirely formed of only a second resin in the thickness direction. In a thin two-color molded product in which the second resin is integrally continuous with the second resin on the front side of the two-layer part, the two-layer part is located at a position adjacent to the two-layer part on the back surface of the one-layer part. A thin wall having a protrusion protruding from the back surface, and having a wraparound portion made of a second resin located on the back side of the first resin of the two-layer portion integrally and continuously with the protrusion. Two-color molded product. 2. A mold apparatus for molding a thin-walled two-color molded product according to claim 1, wherein a first mold member forming surfaces of said one-layer part and two-layer part, and said first mold. A second mold member movable in the direction of approaching and separating from the mold member and forming the back surface of the two-layer portion; and a second mold member movable in parallel and independent of the second mold member and independently of the second layer member. A third mold member forming a back surface, and a fourth mold member movable in parallel and independently of the second mold member and the third mold member to form a back surface of the convex portion and the wraparound portion. A molding member for a thin-walled two-color molded product, wherein a gate for a second resin is provided at a position of the second molding member which is opened and closed by a fourth molding member. Mold device.