JP2525240B2 - Tape cartridge - Google Patents

Description

The present invention relates to a tape cartridge having a transparent window for visually recognizing the tape winding amount and the like.

[Prior Art] As a cartridge case of this type of tape cartridge, for example, as shown in FIG. 8, a case body 3 having a window hole 2 is primarily molded by a two-color injection molding method, and then the window hole 2 is formed.
It is publicly known that the transparent window plate 5 is secondarily molded therein.

[Problems to be Solved by the Invention]

The problem is that in the two-color injection-molded cartridge case, the transparent window plate 5 is deformed so that the seam 17 with the case body 3 is widened toward the case body 3 as shown by the broken line A in FIG. Or the resin is likely to squeeze out (flow). In particular, molding defects such as such deformation and resin extrusion often occur near the secondary molding gate portion G. This is because after the case main body 3 is primarily molded, a secondary molding space is formed between the case main body 3 and the mold, and the secondary molding resin is injected into the space from the gate portion G to form a transparent window plate. 5 is molded, but the molding conditions such as the filling pressure, the filling amount, and the filling speed of the secondary molding resin at this time are set relatively high so that sink marks do not occur at the corners of the transparent window plate 5. Therefore, it is considered that the case body 3 as a primary molded product loses its strength and is deformed by the filling pressure of the secondary molded resin.

The present invention has been made by paying attention to these facts. By improving the cross-sectional shape of the case body (primary molded product) in the vicinity of the joint with the transparent window plate (secondary molded product), the transparent window is improved. The purpose is to eliminate molding defects such as deformation of the plate and case body and resin protrusion.

Another object of the present invention is to ensure prevention of detachment at the joint of the transparent window plate with the case body.

[Means for solving the problem]

In the tape cartridge of the present invention, for example, as shown in FIG. 1, a case body 3 of a primary molded article is provided with a transparent window plate having a two-layer cross-section structure composed of an outer layer 5b and an inner layer 5a narrower than the outer layer 5b. Next molded, on the outer surface of the case body 3,
Primary molding is performed at a position slightly separated from the joint 17 with the outer layer 5b of the transparent window plate 5 and at a position slightly separated from the joint 17 with the inner layer 5a of the transparent window plate 5 on the inner surface of the case body 3. The concave groove 7 formed by the convex portion 11 provided in the mold is provided along the seam 17.

[Action]

In that case, the secondary molding resin pressure is not only received by the case body 3 of the primary molding product, but also by the concave groove 7 of the case body 3, that is, the convex portion 11 provided in the primary molding die. Therefore, the secondary molding resin pressure applied to the case body 3 can be reduced accordingly.

The concave groove 7 may be provided at the position of the seam 17 with the transparent window plate 5 of the case body 3 as shown in FIG. 7 only for reducing the pressure of the secondary molding resin applied to the case body 3. However, in such a case, however, the plate thickness at the joint 17 with the transparent window plate 5 of the case body 3 becomes thin, and the joint strength with the transparent window plate 5 of the case body 3 is reduced and halved. In that respect, if the concave groove 7 is set at a position slightly apart from the position of the joint 17 with the transparent window plate 5 of the case body 3, the plate thickness at the joint 17 with the transparent window plate 5 of the case body 3 is set. It is possible to secure a bonding area with the transparent window plate 5 without thinning.

〔The invention's effect〕

The tape cartridge of the present invention is provided with a concave groove 7 formed by the convex portion 11 provided in the primary molding die at a position slightly separated from the joint 17 of the case body 3 with the transparent window plate 5, The secondary molding resin pressure is also received by the concave groove 7 portion. Therefore, even if the molding conditions such as the filling amount of the secondary molding resin, the filling pressure, and the filling speed are not severely set, the pressure occurs in the case where the secondary molding resin pressure is received only by the case main body 3 and the window plate 5 and the case. Molding defects such as deformation of the main body 3 and protrusion (flow) of resin can be well prevented. Further, since the filling pressure of the secondary molding resin can be set to be large, it is possible to eliminate the occurrence of sink marks on the window plate 5. Further, since the joint strength between the case body 3 and the transparent window plate 5 can be secured, the transparent window plate 5 does not come off due to an external load or the like, and has excellent durability. In particular, the cross-sectional shape of the transparent window plate 5 has an outer layer 5b and an inner layer narrower than the outer layer 5b.
Since it has a two-layer cross-sectional structure consisting of 5a, when the transparent window plate 5 and the case body 3 are integrally joined, the portion of the outer layer 5b that projects from the inner layer 5a is received and supported by the concave portion of the outer surface of the case body 3. At the same time, the joint area with the case body 3 can be increased, and the joint strength can be increased. Therefore,
The transparent window plate 5 receives a load from the outside and the case body 3
It has excellent durability because there is no danger of it falling off inside. Further, since the groove 7 is provided on both inner and outer surfaces of the case body 3, it is possible to well prevent the inner surface and the outer surface of the case body 3 and the inner layer 5a and the outer layer 5b of the transparent window plate 5 from being deformed by the secondary molding resin pressure. Even if the transparent window plate 5 has a two-layer cross-section structure, there is an advantage that it is excellent in preventing deformation and preventing defective molding.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is an external plan view of the cartridge case, and FIG. 2 is an internal plan view thereof. The cartridge case 1 includes a case body 3 having a window hole 2 and a drive shaft insertion hole 4, and a transparent window plate 5 integrally molded in the window hole 2 of the case body 3. The window holes 2 are formed so as to penetrate the inside and outside of the case body 3 at an intermediate position between the left and right drive shaft insertion holes 4 and 4 of the case body 3 and at both ends thereof, respectively. The open end is a recess 6 formed on the outer surface of the case body 3 with a constant width over the entire length in the left-right direction.
It is formed in a shape to face. As shown in FIG. 3, the transparent window plate 5 has an inner layer 5a that fills each window 2 and an outer layer that fills the recess 6.
It has a two-layer cross-section structure of 5b. Then, on the outer surface of the case body 3, a joint 17 with the outer layer 5b of the transparent window plate 5 is formed.
A concave groove 7 is formed along the seam 17 at a position slightly away from. Further, a concave groove 7 is similarly formed on the inner surface of the case body 3 at a position slightly apart from the joint 17 with the inner layer 5a of the transparent window plate 5.

For example, if the thickness t of the case body 3 is 1.8 mm,
It is preferable that the depth d of the groove 7 is set to 0.1 mm or more, and the distance H between the groove 7 and the seam 17 is set to 10 mm or less.

The cartridge case 1 can be molded by the core back type two-color injection molding method as follows.

FIGS. 4A and 4B show the structure of a two-color injection molding die. FIG. 4 (a) shows the primary molding state, in which the primary molding space is provided between the fixed side insert 8 and the movable side insert 9.
Forming 10. The fixed-side insert 8 and the movable-side insert 9 are provided with a convex portion 11 for forming a concave shape, and the recesses and the slide cores 12 and 13 for forming window holes are set in abutment with each other. . Thus, the case body 3 is molded by filling the primary molding resin 10 into the primary molding space 10 from the primary molding gate 14. Next, as shown in FIG. 4 (b), the slide core 12 for forming the recess is brought to the outer surface height position of the case body 3, and the slide core 13 for forming the window hole is formed at the inner surface height position of the case body 3. The secondary molding space 15 is formed between the main body 3 and the case body 3 as the primary molding product, and the transparent resin is molded into the secondary molding space 15 in the secondary molding gate.
By filling the transparent window board 5 from the case body 3 from 16
The cartridge case 1 is obtained by secondary molding integrally with. During this secondary molding, the secondary molding resin pressure is received by the convex portions 11 of the fixed-side insert 8 and the movable-side insert 9. Therefore, the transparent window plate 5 and the case body 3 are deformed by the secondary molding resin pressure. It could be molded well without the resin sticking out. Further, since the location where the convex portion 11 is present is provided not at the position of the seam 17 between the case body 3 and the transparent window plate 5, but at a position slightly apart from it, The plate thickness of the seam 17 can be secured, and the entire plate thickness of the window plate 5 can be joined to the entire plate thickness of the case body 3 to secure its integral joining strength.

Second Embodiment FIG. 5 shows a second embodiment of the present invention. In this embodiment, unlike the shape of the transparent window plate 5 shown in FIG. 1 in which the outer layer 5b reaches the left and right ends of the case body 3, the case body 3 surrounds the front, rear, left and right sides. The transparent window board 5 of the shape is mentioned. In the case of such a shape of the transparent window plate 5, it is necessary to provide the concave grooves 7 on the inner surface of the case body 3 at the front, rear, left and right positions of the transparent window plate 5. By the way, in the shape of the transparent window plate 5 shown in FIG. 1, since the secondary molding resin pressure on the left and right side surfaces is received by the case body molding die, it is necessary to provide the concave groove 7 at that portion. There is no.

[FIG. 3 Embodiment] FIG. 6 shows a third embodiment of the present invention in which a groove 7 is formed wide so that a title label can be attached thereto.

[Other Examples]

Further, the concave groove 7 need not be a straight line continuous in the direction along the seam 17, but may be formed intermittently in that direction.

[Brief description of drawings]

1 to 4 (a) and (b) show a first embodiment of a tape cartridge according to the present invention. FIG. 1 is an external plan view of a cartridge case, and FIG. 2 is an inside of the cartridge case. Plan view, FIG. 3 is III-III in FIG.
A line cross-sectional view and FIGS. 4A and 4B are cross-sectional views of the molding die. FIG. 5 is an internal plan view of the cartridge case showing the second embodiment of the present invention. FIG. 6 is an external plan view of the cartridge case showing the third embodiment of the present invention. FIG. 7 is a cross-sectional view of essential parts showing a defective example. FIG. 8 is an external plan view of a conventional tape cartridge. 2 ... Window hole, 3 ... Case body, 5 ... Transparent window plate, 7 ... Recessed groove, 11 ... Convex portion.

Claims (1)

(57) [Claims] 1. A transparent window plate 5 having a two-layer cross-section structure, which comprises an outer layer 5b and an inner layer 5a narrower than the outer layer 5b, is secondarily formed on a case body 3 of a primary molded article. On the outer surface, a position slightly separated from the joint 17 with the outer layer 5b of the transparent window plate 5, and the case body 3
The inner surface of the transparent window plate 5 is formed at a position slightly distant from the joint 17 with the inner layer 5a, and the concave grooves 7 formed by the convex portions 11 provided in the primary molding die are formed along the joint 17 respectively. A tape cartridge characterized by being provided in a shape.