Moulded Cap With A Gasket
A gasket is provided in a cap mould for sealing a container
, especially for a container to be used for liquids such as liquid fuels to prevent leakage thereof. In general, the gasket is made of a rubber material. The rubber material expands or shrinks due to an effect of the fuel within the container. As a result, the gasket sometimes falls off from the cap when the cap is opened. If the cap is closed again without the gasket, it causes the leakage of the fuel.
The inventors of the present invention realized that the cause for requiring the separate machining process or the complex mould is due to the fact that the undercut for securing the gasket is extending in a direction perpendicular to a direction of removing the mould. Therefore, in the present invention, the undercut is made by forming a vertical hole in the top wall of the cap mould which extends in the same direction as that of removing the mold or ejecting the moulded cap. The mould for forming the outer shape of the cap is provided with a plurality of protrusions, each having a complementary shape with the vertical hole. The protrusion extends straight in the same direction as that of removing the mould or ejecting the moulded cap. Therefore, the present invention enables to remove the cap to be removed from the mould by simply translating the mould in a straight motion or by ejecting the moulded cap.
The cap mould according to the present invention can be integrally formed with a simple mould provided with a plurality of protrusions on the mould for forming an outer shape of the cap. Each protrusion is formed in a complementary shape with the shape of the vertical hole. Since the protrusion extends straight in a vertical direction, the cap having an undercut can be removed from the mould by simply translating the mould straight in the vertical direction or ejecting the moulded cap in the vertical direction. When the gasket is mounted on the moulded cap, the ears thereof are supported on the shelves formed in the skirt near the boundary region between the top wall and the skirt of the cap. The ears are held on the shelves by the self-sustaining shape of the gasket or friction between the surfaces of the ears and the shelves, whereby falling of the gasket is prevented. Further, since the ears can be observed through the vertical holes from outside, the presence of the gasket and whether the spout is sealed or not can be checked by looking into the vertical holes without actually removing the cap mould from the spout.
by: ericfu