JPH04103379U - Housing for magnetic tape cassette and its molding die - Google Patents

Abstract

(57) [Summary] (with amendments) [Purpose] When molding a magnetic tape cassette housing using a resin material with high specific gravity, burrs occur even when the joint surface of the core is eliminated and the injection pressure is high. Make it difficult.
This speeds up the housing molding cycle without insulating the core at high temperatures, resulting in high productivity. [Structure] The guide protrusion 10 near the center of the half of the side rib 2 of the half 1 is constituted by a columnar protrusion formed apart from the side rib 2. Moreover, regarding the mold for molding this, a core g forming the front surface of the center rib 8 and the side rib 2 is integrally formed, and a columnar guide protrusion 1 formed apart from the side rib 2 is formed in the core g.
A cavity for molding 0 is formed. As a result, when the fixed mold and the movable mold are combined, a joint surface of the core is not formed at the boundary between the center rib 8 and the side rib 2.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is a magnetic tape cassette having a center rib 8 and side ribs 2 on the front side. related to cut housings and molds for molding them.

0002

[Conventional technology]

Housings for magnetic tape cassettes are generally made of a pair of resin parts called halves. A box shape is formed by overlapping and fixing the molds. A housing like this An example of a conventional half configuration is explained with reference to FIG. 4. As shown in FIG. 4(a), Half 1 is a box-shaped housing divided in half, with magnetic tape wrapped in the center. Hub holes 5, 5 for pivotally supporting the hub are provided. Also, on the back, its magnetic A position hole portion 6 is formed to display the position of the tape cassette. . On the other hand, a center rib 8 and a side rib 2 are formed on the front side. Guide protrusions 3 and 4 are integrally formed therefrom. Furthermore, the front of side rib 2 A capstan hole 7 is opened, and a protrusion 9 forming a window frame is formed on the front side. ing.

0003 Such a half 1 is molded by an injection molding method using an injection mold. . FIG. 4(b) shows an example of the conventional arrangement of the core of the mold forming the peripheral part of the side rib 2. It is shown. As shown in this figure, the core includes side ribs 2, center ribs 8 It is divided into a and c to f according to each surface on which the protrusion 9 is to be molded. , when the fixed mold and the movable mold are matched, these cores a, c to f are shown in Figure 2 ( They are joined as shown in b). Then, from the gate b side provided on the core a side, Molten resin is injected into the cavity between the sides, and side ribs are formed inside the cavity. 2 and the center rib 8 are molded.

0004

[Problem that the invention is trying to solve]

Recently, for the purpose of making magnetic tape cassettes more luxurious and improving sound quality, specific gravity 1.2 to 3. ．． The housing for magnetic tape cassettes is molded using so-called high specific gravity resin of 0. things are being done. This high specific gravity resin is made of polystyrene, polypropylene, It is made by adding inorganic fillers such as calcium carbonate to ABS resin or AS resin. Its fluidity is lower than that of general resins that do not contain inorganic fillers. For this reason, resin injection If you do not increase the injection pressure during injection, resin may build up inside the cavity, especially in small areas. It doesn't go around completely. However, if the resin injection pressure is increased, the cores a, c~ There is a problem that resin easily enters between the joint surfaces of f, causing burrs on the molded product. be. Therefore, in the past, in order to increase the fluidity of the resin, the temperature of cores a, c to f was raised. This is done by molding. However, in that case, the molded product is cooled from the core side. It takes time to harden the resin, which lengthens the molding cycle and reduces productivity. There was a problem that the value was low.

[0005] Therefore, in view of the above-mentioned problems, the present invention eliminates the joint surface of the core and increases the injection pressure. The magnetic tape cassette housing and its molding mold are resistant to burrs even when The purpose is to provide.

[0006]

[Means to solve the problem]

That is, in this invention, in order to achieve the above-mentioned purpose, a center is placed on the front side of half 1. In a magnetic tape cassette housing having ribs 8 and side ribs 2, the support Remove the guide protrusion 10 near the center of the half 1 of the idle rib 2 from the side rib 2. A magnetic tape cover comprising pillar-shaped protrusions formed apart from each other. Provides a housing for the set. Furthermore, a core forming a center rib 8 and side ribs 2 on the front side of the half 1 In the magnetic tape cassette housing mold, the center rib 8 A core g forming the front surface of the side rib 2 and the side rib 2 is integrally formed, and a size is inserted into the core g. A cavity portion forming a columnar guide protrusion 10 formed apart from the drib 2 Provides a mold for housing a magnetic tape cassette, which is characterized by the formation of a do.

[0007] In the magnetic tape cassette housing according to the present invention, the heart of the side rib 2 is A pillar in which the guide protrusion 10 near the center of the flap 1 is formed away from the side rib 2. The front surface of the center rib 8 and the side ribs 2 is A core g forming the core g is integrally formed, and a pillar formed therein apart from the side rib 2. It is possible to form a cavity portion that forms the guide protrusion 10 having a shape. subordinate Therefore, the joint surface of the core is reduced. In particular, the border between center rib 8 and side rib 2 The boundary part is the part that is most susceptible to the pressure of the resin injected from the gate b side, By eliminating the joint surface of the core here, resin can be injected into the cavity. Even if the pressure is increased, burrs will occur on half 1 due to resin entering the joint surface. Not alive.

[0008]

【Example】

Next, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1(a) shows one part of the magnetic tape cassette housing according to the present invention. 2 is a drawing showing the inside of one half 1. Its basic configuration is the same as the conventional half The common parts are indicated by the same reference numerals as in FIG. 4(a). Furthermore, in Figure 1 (b) shows the arrangement of the core of the mold forming the peripheral part of the side rib 2 of the half 1. This is an example, and parts common to FIG. 4(b) are indicated by the same reference numerals.

[0009] As already mentioned, in the present invention, the central portion of the side rib 2 of the half 1 is The guide protrusion 10 is formed by a columnar protrusion formed apart from the side rib 2. Configure. In addition, regarding the mold for molding this, the center rib 8 and the side A core g forming the front surface with the rib 2 is formed integrally with the core g, and a core g is formed therein, which is separated from the side rib 2. A cavity portion is formed in which the columnar guide protrusion 10 is formed. As a result, when the fixed mold and the movable mold are combined, the center rib 8 and the side rib A joint surface of the core is not formed at the boundary with the core 2. In the illustrated embodiment, the guide protrusion 10 is a cylindrical protrusion, and the guide protrusion 10 is a cylindrical protrusion. A cross section taken along the line A-A in FIG. 1(b) of the mold forming the peripheral portion of the idle rib 2 is shown. As is clear from Figure 2, the access from gate b to the cavity in that part is from gate b to half 1. Resin is injected through the bottom part.

0010 FIG. 3 is an example showing the vicinity of the side rib 2 of the half 1 formed by the mold. be. Figure (a) shows a case where the heights of the side ribs 2 and center ribs 8 are different. The former is about twice as high as the latter. Figure (b) shows side rib 2 and center This is for the case where the heights of the talibs 8 are the same. In both cases, the center of half of side rib 2 The closer guide protrusion 10 is formed from a columnar protrusion formed apart from the side rib 2. ing.

[0011]

[Effect of the idea]

As explained above, according to the present invention, the injection pressure of resin into the cavity is increased. However, since burrs caused by resin entering the joint surface do not occur, the core There is no need to perform injection molding at a high temperature. Therefore, the housing molding service A housing for magnetic tape cassettes that uses high-density resin without slowing down the cycle. The effect is that it can be molded with high productivity.

[Brief explanation of drawings]

FIG. 1 is an inner view (a) of one half constituting a magnetic tape cassette housing according to an embodiment of the present invention, and an enlarged cross-sectional view (b) of essential parts showing the arrangement of cavities molded around the side ribs. be.

FIG. 2 is a sectional view taken along line AA in FIG. 1.

FIG. 3 is a perspective view of essential parts showing an example of the shape of the vicinity of the side ribs of one half of the magnetic tape cassette housing according to the embodiment of the present invention.

FIG. 4 is an inner view (a) of one half constituting a conventional magnetic tape cassette housing, and an enlarged sectional view (b) of a main part showing the arrangement of a cavity molded around the side ribs thereof.

[Explanation of symbols]

1 half 2 side ribs 8 center rib 10 Guide protrusion a core c core d core e core f core g core

Claims (2)

[Reference number] 0020779-01 [Scope of utility model registration request] 1. In a magnetic tape cassette housing having a center rib (8) and a side rib (2) on the front side of the half (1), a guide protrusion ( 10) is constituted by a columnar projection formed apart from the side rib (2). 2. A housing mold for a magnetic tape cassette comprising a core forming a center rib (8) and a side rib (2) on the front side of the half (1), wherein the center rib (8) and the side rib A cavity portion in which a core (g) forming a front surface with (2) is integrally formed, and a columnar guide protrusion (10) formed in the core (g) apart from the side rib (2). A mold for forming a housing for magnetic tape cassettes.