JPH076554A - Method for molding tape cassette half - Google Patents

Abstract

PURPOSE:To prevent unnecessary resin leakage at the time of two-color molding by using a male type stationary metal mold which regulates the shape of the inside wall of a reel hub guide and a female type moving metal mold which has the diameter larger than, the diameter of this mold and regulates the outside wall of the guide. CONSTITUTION:The stationary metal mold 15 is provided with a cylindrical male mold type 16 which regulates the shape of the inside wall of the reel hub guide 14a (14b) in the prescribed position and the moving metal mold 17 is provided with a female mold 1 7 which regulates the outside wall of the guide 14a in the prescribed position. The circular conical recessed part of the female mold 17a is formed to the diameter larger than the diameter of the base trunk part 16b of the male mold 16. The resins 20, 21 for molding a frame part 2a are injected in the state A partitioning the section forming the guide 14a and the section forming a frame part 2a of the cassette half body. The metal mold 17 is thereafter moved and the resins 22, 23 molding the guide 14a are injected in the state B having the spacing to form the guide 14a. The unnecessary leakage of the resins 20, 21 is eliminated by such two-color molding method, by which the good tape cassette half is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape cassette half molding method suitable for molding a tape cassette half with various kinds of resins.

[0002]

2. Description of the Related Art Generally, a tape cassette shown in FIG. 2 has been proposed. In FIG. 2, reference numeral 1 denotes a cassette housing, and this cassette housing 1 is formed by combining a pair of cassette halves 2 and 3 by screwing. The frame portions 2a and 3a of the cassette halves 2 and 3 are made of opaque, for example, black thermoplastic resin.

Reference numeral 4 is a magnetic tape loaded in the cassette housing 1, and the magnetic tape 4 is wound around a reel hub 6. Reference numeral 5 denotes a window portion provided over a range larger than the maximum winding diameter of the magnetic tape 4 wound around the reel hub 6, and the window portion 5 is made of a transparent resin such as styrene resin.

Though not shown in FIG. 2, the cassette half 3 also has a window 5 formed therein. The winding state of the magnetic tape 4 wound around the reel hub 6 in the cassette housing 1 can be easily viewed through the window 5. Then, in the window portion 5, reel shaft insertion holes 7a and 7b having reel hub guides are formed along the outer periphery in which the reel hub 6 is loosely fitted so as to be rotatable.

Reference numeral 8 indicates a scale portion formed in a convex shape on the window portion 5 as a measure of the winding amount of the magnetic tape 4. Reference numeral 9 denotes a central opening provided on the front surface of the cassette housing 1, and the recording / reproducing head is inserted into the front surface of the cassette housing 1 through the central opening 9 during recording or reproduction. There is.

Reference numerals 10a and 10b denote central openings 9 respectively.
The small windows 11a and 11b are arranged symmetrically with respect to the central opening 9 and the openings 12a, 12b and 13a, 13b are arranged symmetrically with respect to the central opening 9 outside the small windows 10a and 10b, respectively. It is a capstan insertion hole and a positioning hole.

By the way, recently, in order to simplify the manufacture, the cassette half is molded by two-color molding in which the frame 2a and the window 5 or the frame 3a and the window 5 are continuously molded using a movable mold. Was requested.

That is, in forming the frame portions 2a, 3a and the window portion 5 of the cassette halves 2 and 3, two types of different color resins are poured into a frame defined by a movable mold to form a tape cassette half molding method. Requested. In particular, FIG.
As shown in Fig. 5, the periphery of the reel hub guides 14a and 14b formed along the outer circumferences of the reel shaft insertion holes 7a and 7b must be formed by making the inner wall and the outer wall in correspondence with each other. However, there is a problem that the resin for primary molding flows out to the portion of the resin layer for secondary molding.

In view of the above points, the present invention is to provide a tape cassette half molding method capable of favorably obtaining a tape cassette half by two-color molding.

[0010]

The tape cassette half molding method of the present invention is, for example, as shown in FIG. 1, reel hub guides 14a and 14b and cassette half body frame portions 2a and 3a.
In the method of forming the tape cassette half, which is formed of different resins,
Fixed mold 15 having a cylindrical male mold 16 that defines the shape of the inner walls of the reel hub guides 14a and 14b of No. 3 in a predetermined position.
And a female die 17a defining the outer walls of the reel hub guides 14a, 14b corresponding to the cylindrical male die 16 is provided at a predetermined position, and the diameter of the conical recess of the female die 17a is set to the male die 1
The reel hub guide 14a, by contacting the movable mold 17 having a diameter larger than that of the trunk portion 16b
14b and the cassette half body frame 2
Resins 20 and 21 forming the cassette half body frame portions 2a and 3a are injected in a state where the sections for molding a and 3a are separated, and then the movable mold 17 is moved to move the reel hub guides 14a and 14b. To create a gap that forms
Resin 2 for molding the reel hub guides 14a, 14b
2 and 23 are injected and molded.

[0011]

According to the present invention, since the diameter of the main portion 16b of the male die 16 is made smaller than the diameter of the conical recess of the female die 17a, the resins 20 and 21 used in the primary molding can be kept in an unnecessary range accurately. The cassette half frame 2 is satisfactorily defined in a predetermined shape.
a and 3a can be formed, and the tape cassette half can be obtained by a simple process of two-color molding.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tape cassette half molding method of the present invention will be described below with reference to FIG. This Figure 1
In FIG. 2, parts corresponding to those in FIGS. 2 and 3 are designated by the same reference numerals and detailed description thereof will be omitted.

In FIGS. 1A, 1B and 1C, reference numeral 15 denotes a fixed mold, and a cylindrical male mold 16 for defining the shape of the inner wall of the reel hub guide of the tape cassette half is provided at a predetermined position of the fixed mold 15. Reference numeral 17 denotes a first movable mold, and the first movable mold 17 is provided with a female mold 17a that corresponds to the cylindrical male mold 16 and defines the outer wall of the reel hub guide of the tape cassette half.

Further, 18 is arranged in the first movable mold 17 so as to be movable relative to the first movable mold 17,
Surface 1 that contacts the cylindrical male head 16a of the fixed mold 15
8a shows a second movable mold having 8a. Reference numeral 19 indicates a third movable mold, and the third movable mold 19 and the fixed mold 1
When the 5 are joined together, the cassette half frame portions 2a to 3a are formed between them.

The diameter of the main portion 16b of the male die 16 is a,
When the diameter of the conical recess of the female die 17a is b, a <b. The other parts are formed in the same manner as the conventional core-back type tape cassette half molding apparatus.

To form a tape cassette half using the tape cassette half molding apparatus of this embodiment having the above-described structure, the following steps are performed.

First, in the first step, the first, second and third movable molds 17, 18, 19 are brought into contact with the fixed mold 15 as shown in FIG. 1A.
To the position of, and, for example, black resins 20 and 21 are injected, and primary molding is performed to form the frame portions 2a to 3a.
Since the diameter b of the conical concave portion of the female die 17a is set to be larger than the diameter a of the main portion 16b, the resins 20 and 21 are securely pushed between the fixed die 15 and the first movable die 17. (FIG. 1A).

Next, as a second step, the first movable mold 17 is retracted to form a gap for molding the window 5, especially the reel hub guides 14a and 14b, as shown in FIG. 1B.
The transparent resins 22 and 23 are injected to carry out secondary molding. At the time of this secondary molding, the resin layer forming the frame portions 2a and 3a and the resin layer forming the window portion 5 are simultaneously joined. After cooling, the movable molds 17, 18 and 19 are separated from the fixed mold 15 again as shown in FIG. 1C, and the tape cassette half formed by two-color molding is taken out.

As described above, in this embodiment, since the diameter b of the conical concave portion of the female die 17a is made larger than the diameter a of the male base portion 16b, the primary molding shown in FIG. 1A is performed. The fixed mold 15 is brought into contact with the entire upper surface of the first movable mold 17, and the shape of the cassette half frame 2a or 3a is accurately defined by the resins 20 and 21. Then, the first movable mold 17 is retracted so that the shape of the window 5 and the reel hub guide is set to the lower part of the fixed mold 15, the male mold 16, as shown in FIG. 1B.
Secondary molding is performed by injecting the resins 22 and 23, which is defined by the movable molds 17 and 18, and after cooling, the movable molds 17, 18 and 19 are separated from the fixed mold 15 as shown in FIG. 1C and two-color molding is performed. The tape cassette half according to the above will be taken out.

As described above, according to this embodiment, the diameter a of the main portion 16b of the male die 16 is made smaller than the diameter b of the conical recess of the female die 17a, so that it is used in the primary molding. Since the resin does not leak into the unnecessary range and is accurately defined in the predetermined shape, the cassette half frame portion 2a or 3a can be satisfactorily formed. Therefore, there is an advantage that a tape cassette half can be satisfactorily obtained by a simple process of two-color molding, which is a great contribution to mass production of tape cassette halves.

Further, according to this example, the reel hub guide 14
Since the a and 14b are formed by the secondary molding, the window 5 is formed over a wide area including the reel hub guides 14a and 14b as compared with the case where the window is formed by the secondary molding only on a predetermined flat surface. Therefore, there is an advantage that the visibility of the tape state in the tape cassette is improved.

The present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0023]

According to the method of molding a tape cassette half of the present invention, the diameter of the cylindrical male-shaped core portion formed on the fixed mold and defining the shape of the inner wall of the reel hub guide of the tape cassette half, Since the diameter of the conical concave portion of the female mold, which is formed in the first movable mold and corresponds to the cylindrical male mold and defines the outer wall of the reel hub guide, is smaller than that of the resin injected during the primary molding. Since the shape is accurately defined and unnecessary resin leakage can be prevented, there is an advantage that good tape cassette halves can be obtained in a simple process by two-color molding, which greatly contributes to mass production of tape cassette halves. is there.

Further, according to the present invention, since the reel hub guide is formed by the secondary molding, a wide range including the reel hub guide is provided as compared with the case where the window portion is formed by the secondary molding only on a predetermined flat surface portion. To form a window,
There is the benefit of improved visibility of the tape status within the tape cassette.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a method of molding a tape cassette half according to the present invention.

FIG. 2 is a perspective view showing an example of a tape cassette.

FIG. 3 is an enlarged cross-sectional view showing an example of a main part of FIG.

[Explanation of symbols]

 2,3 Tape cassette half 2a, 3a Frame part 5 Window part 14a, 14b Reel hub guide 15 Fixed mold 16 Cylindrical male mold 16b Core part 17 Movable mold 17a Female mold

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[Procedure amendment]

[Submission date] February 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

That is, in forming the frame portions 2a, 3a and the window portion 5 of the cassette halves 2 and 3, two types of different color resins are poured into a frame defined by a movable mold to form a tape cassette half molding method. Requested. However, if the window 5 is formed first and then the frames 2a and 3a are formed later, a high pressure is applied to the resin for forming the frames 2a and 3a so as to circulate around the window 5. It is necessary to inject the resin over, and there is a possibility that the contour of the window portion 5 previously formed may be broken by the injection of the resin. Therefore, it is conceivable to first form the frame portions 2a and 3a and then form the window portion 5. In this case, in particular, as shown in FIG. 3, the frame portions 2a and 3a are formed along the outer circumferences of the reel shaft insertion holes 7a and 7b. Since the inner walls and the outer walls of the reel hub guides 14a and 14b must be molded in such a manner that the inner wall and the outer wall are made to correspond to each other, the resin for the primary molding may be different from the resin for the secondary molding depending on the shape of the movable mold. There was a problem of spillage into layers.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

First, in the first step, the first, second and third movable molds 17, 18 and 19 are brought into contact with the fixed mold 15 as shown in FIG. 1A.
To the position of, and, for example, black resins 20 and 21 are injected, and primary molding is performed to form the frame portions 2a to 3a.
Here, since the diameter b of the conical concave portion of the female die 17a is made larger than the diameter a of the basic portion 16b, the resins 20 and 21 are securely pushed between the fixed die 15 and the first movable die 17. (FIG. 1A).

Claims (1)

[Claims] 1. A method of molding a tape cassette half, wherein a reel hub guide and a cassette half body frame are molded from different resins, respectively, wherein a cylindrical male mold that defines the shape of the inner wall of the reel hub guide of the tape cassette half. A fixed mold having a predetermined position,
A movable mold having a female mold for defining the outer wall of the reel hub guide at a predetermined position corresponding to the cylindrical male mold and having a conical concave portion of the female mold larger in diameter than the male main body. By injecting the resin forming the cassette half body frame portion into a state where the section for forming the reel hub guide and the section for forming the cassette half body frame portion are separated by contacting with each other. A method of molding a tape cassette half, characterized in that a mold is moved to form a gap for forming the reel hub guide, and a resin for molding the reel hub guide is injected to perform molding.