JPH0657418B2 - Hinge cap molding method - Google Patents

Description

The present invention relates to a method for molding a synthetic resin hinge cap.

[Prior Art] There is a synthetic resin hinge cap whose lid is integrally formed with the cap via a hinge. This type of hinge cap is usually manufactured by injection molding, but if the cap a is a divergent type as shown in FIG. 3, the hinge lid b side is undercut, so the slide core c is inevitably formed. It will be used for molding.

[Problems to be Solved by the Invention] In the injection molding of the hinge cap as described above, the lid b is an obstacle for releasing the slide core c. Therefore, as shown in FIG. Push-up device d
Must be pushed out of the slide core c by
Since it is performed before the synthetic resin is completely cured, the rod e is pushed on the surface of the lid b, and the commercial value of the cap is significantly reduced.

In order to prevent such a situation, for example, the mold may be divided so that the lid b does not get in the way when the slide core is released from the mold, but the number of molds increases and the cost becomes high, and preparation for manufacturing is performed. Becomes troublesome, resulting in inconvenience such as reduced work efficiency.

[Means for Solving the Problem] The present invention has been made in order to cope with the conventional situation as described above, and as a technical solution thereof, a lid body is integrally formed on a cap body via a hinge. In the case where the lid body is injection-molded from a synthetic resin into a hinge cap in which a peripheral wall is widened toward the end and a cylindrical plug is provided on the inner surface, an undercut is formed at the tip of the cylindrical plug, and the undercut is separated via the undercut. The gist of the invention is to lift the lid by raising the die during the die and remove it from the slide core for molding the lid.

[Operation] When the mold is released after injection molding, the lid is lifted as the lid core rises and is automatically detached from the slide core. The slide core can be released smoothly without being scratched.

[Examples] Hereinafter, the present invention will be described in more detail with reference to the illustrated examples.

Reference numeral 1 denotes a cap body, which has a discharge port 1a on the upper surface thereof, and a lid body 3 which is connected to the side edge of the upper end portion via a hinge 2. A peripheral wall of the lid 3 is widened toward the end (inverted in the figure, it is widened upward), and a cylindrical plug 3a that engages with the discharge port 1a is projectingly provided on the inner surface, and a tip portion thereof is formed into an undercut 3b. It is molded.

The cap having the above structure is manufactured by injection molding of synthetic resin as in the conventional case, and at the time of this molding, the lid body 3 has the slide core 4 and the lid core 5 as shown in FIG.
It will be dressed between and.

Although the mold is released after injection molding, in the case of the present invention, since the tip of the cylindrical plug 3a of the lid body 3 is molded into the undercut 3b as described above, when the lid core 5 is raised, the undercut 3b Is caught, the lid body 3 rises together with the lid core, and is automatically disengaged from the slide core 4. After this,
As shown in FIG. 2, the slide core 4 can be slid laterally and released. At this time, the hinge 2
Is pushed by the protrusion 4a at the end of the slide core 4 and is rotated counterclockwise, so that the lid 3 is lifted further upward, and there is almost no mold release resistance of the slide core 4, and it can be removed extremely smoothly. Can be done. This eliminates the need for a push-up device for forcibly removing the lid body 3, unlike the conventional case, and does not leave a pushing mark on the lid body at all.

[Effects of the Invention] As described above, according to the present invention, in the injection molding of the cap with lid, the tip end of the cylindrical plug projecting on the inner surface of the lid is formed into an undercut, so that the lid core is released at the time of mold release. The lid automatically disengages from the slide core when the lid is lifted, and therefore, it is possible to completely prevent the lid from pushing up by the push-up device and increase the commercial value. In addition to the smoothness, the die structure is the same as the conventional one, and thus it has excellent effects such as a reduction in work efficiency and an increase in cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, FIG. 2 is a sectional view of an essential part showing a state in which a lid core is removed and then a slide core is released, and FIG. 3 is an explanation of a conventional example. FIG. 4 and FIG. 4 are cross-sectional views of essential parts showing a state in which the lid is forcibly removed by the conventional push-up device. 1 ... Cap body 1a ... Discharge port 2 ... Hinge 3 ... Lid body 3a ... Cylindrical plug 3b ... Undercut 4 ... Slide core 5 ... Lid core

Claims (1)

[Claims] 1. A method of injection-molding a hinge cap made of synthetic resin, wherein a lid body is integrally molded to a cap body via a hinge, a peripheral wall of the lid body is widened toward the end, and a cylindrical plug is projectingly provided on an inner surface of the hinge cap. A hinge characterized in that an undercut is formed at the tip of the cylindrical plug, the mold is lifted through the undercut to raise the lid, and the lid is removed from the slide core for molding the lid. Cap molding method.