JPH029075A - Tape cassette - Google Patents

Abstract

PURPOSE:To thrust out halves from a mold without deformation by providing build-up around the inside of a part, which is thrusted by a thrust pin at the time of release from the mold, of a pair of upper and lower halves formed by injection molding. CONSTITUTION:A tape cassette is internally provided with reels around which a tape should by wound and has a pair of upper and lower halves formed by injection molding. A half 2 is thrusted out from the mold by a thrust pin 6, and the thrust pin 6 has a circular section. The thrust pin 6 has a cut part 6a on the peripheral wall of the front end and has a columnar part 6b, whose diameter is smaller than that of the thrust pin 6 itself, in the center of the front end. The inside peripheral part of the part of the half 2 which is thrusted by the thrust pin 6 is raised because of the cut part 6a to form an annular build-up 8. Thus, mold release defects such as cracks and break of the half at the time of thrust is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tape cassette containing a reel wound with tape.

2. Description of the Related Art Conventionally, this type of tape cassette has been constructed as shown in FIG.

FIG. 2 is an external view of a VH3 type tape cassette, in which a pair of reels (not shown) wound with tape are housed in a box consisting of an upper half 1 and a lower half 72. Transparent windows 3, 3 are welded to the half 1 so that the tape wound on the internal reel can be seen. A lid 4 is rotatably attached to the half 1 on the front side of the box. FIG. 3 shows a cross-sectional view of the half 2 taken in its longitudinal direction. FIG. 3 shows the half 2 about to be ejected from the mold 5 by means of the ejector pin 6.6.

FIG. 4 shows an enlarged view of the vicinity of one tip of the ejector bottle 6 in FIG. 3. In FIG. 4, the mold 6 is omitted.

Problems to be Solved by the Invention However, in such a conventional configuration, when the protruding bottle 6 pokes the half 2, the half 2 may bulge as shown in FIG. 4B, or crack 7 as shown in FIG. When the molding material for 0-half is human BS resin, the above problem is less likely to occur, but when it is styrene resin, it causes white discoloration even without cracking. The above-mentioned problems are likely to occur because the material has low strength and also has poor slipperiness against the mold, requiring a large force to release from the mold.

In recent years, very high-performance styrene materials have been developed for cassettes and are now in common use, but this problem still exists. This problem becomes even more pronounced when attempting to reduce the wall thickness of the nof in order to save molding material.

Means for Solving the Problem In order to solve this problem, the tape cassette of the present invention has the following features:
It is characterized in that a thick padding is provided around the inner circumference of the part of the half that is poked by the ejecting pin, and the inside, that is, the center part of the padding is recessed.

Further, it is characterized in that the half wall thickness at the central portion is thinner than the half wall thickness around the protrusion pin.

Function: Due to this groove bottom, the wall thickness of the portion of the groove that receives shearing force from the ejecting pin becomes thicker due to the build-up, making it difficult to cause deformation or the like. In addition, since the central portion of the portion poked by the ejector pin is thin, it is easily cooled. Instead, the built-up part around it cools well and hardens, making it stronger and less prone to deformation, and also less likely to cause sink marks.

Embodiment FIG. 1 is a sectional view showing a part of a half of a tape cassette according to an embodiment of the present invention, and corresponds to FIG. 4 of the conventional example described above.

Hereinafter, parts corresponding to those in the conventional example will be explained using the same reference numerals, and explanations of overlapping parts will be omitted.

In FIG. 1, the half 2 is ejected from the mold by means of an ejector pin 6. The ejector pin 6 has a circular cross section. The protruding pin 6 has a removed portion 62L on the peripheral wall at its tip, and the protruding pin 6 has a removed portion 62L at the center of the tip.
It has a cylindrical portion 6b having a smaller diameter than the cylindrical portion 6b itself. Half 2,
The inner periphery of the part that is poked by the ejector pin θ is the removed part 6'&
An annular pad 8 is formed.

The outside of the build-up 98 is curved to avoid stress concentration, but it may also be a slope.

The wall thickness t of the half 2 inside the overlay t)8 is the wall thickness t of its surroundings. It has been made equal to or lower than that. This is a common thing, but since the ejector pin 6 is not directly cooled, the temperature tends to be higher than the surrounding mold, so the thickness of the half of this part is made thinner so that it cools quickly and hardens. It is intended to do so.

As a result, the surface area of the overlay 8 also increases, and the area around it cools quickly and hardens, increasing its strength.

Furthermore, the build-up 8 increases the area that receives the shearing force from the protruding pin 6. These factors act synergistically to prevent demolding defects such as deformation and cracking of the half 2 during ejection.

Effects of the Invention As described above, according to the present invention, the half can be ejected from the mold without deformation or the like by simply changing the shape of the vicinity of the tip of the ejector pin.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing how the half of the tape cassette according to the present invention is released from the mold, FIG. 2 is a perspective view showing the external appearance of the tape cassette to which the present invention is applied, and FIG. 3 is a partial sectional view showing how the half of the tape cassette is molded. FIG. 4 is a partial sectional view showing the state in which this occurs. 2...Half, 6...Protruding pin, 8
... Meat pile! llO Name of agent Patent attorney Toshio Nakao and 1 other person 2-
Half 6---Pick-up> 6---Filled filler diagram X/

Claims (2)

[Claims] (1) It is equipped with a reel for winding the tape, and a box formed by a pair of upper and lower halves formed by injection molding, in which the reel is housed, and the halves are provided with an ejecting pin when the mold is released from the mold. A tape cassette with a padded area around the inside of the part that will be poked. (2) The tape cassette according to claim 1, wherein the inner half of the padding is thinner than the outer half.