Dispensing – Nozzles – spouts and pouring devices – Reinforced or with container-connected brace
Reexamination Certificate
1999-12-17
2001-06-26
Derakshani, Philippe (Department: 3754)
Dispensing
Nozzles, spouts and pouring devices
Reinforced or with container-connected brace
C222S001000, C264S255000
Reexamination Certificate
active
06250519
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention refers to a method for producing a nozzle cartridge which can be used as a container for pressing out flowable or thixotrop materials, as well as a device for producing a nozzle cartridge, and finally also a nozzle cartridge.
BACKGROUND OF THE INVENTION
The cartridges used for pressing out flowable or thixotrop materials, e. g. sealing materials, have a cylindrical cartridge body limited at one end by an annular shoulder having an outlet connection projecting therefrom. As a separate part, a nozzle is screwed on the outlet connection provided with an external thread. There are also known nozzle cartridges in which the nozzle is an integral part of the cartridge and is produced integrally therewith. Such nozzle cartridges have the advantage that it is not necessary to mold a complicated thread.
The production of nozzle cartridges takes place by injecting a melt into a mold consisting of an exterior hollow mold and an interior core. In this process, the molten plastic is injected into the mold at a very high pressure, and the thermoplastic then becomes solid by cooling in the mold. A special problem is keeping the core centered in the mold. The core, which does not only fill out the interior of the future cartridge body but also the interior of the nozzle, extends from a core support like a cantilever and projects into the hollow mold. An even wall thickness of the cartridge is only achieved if the core remains exactly centered in the hollow mold. With the applied pressures and the resulting high forces, it is extremely difficult to maintain the central position of the core. A deviation of the core from its central position would result in an uneven distribution of wall thickness of the cartridge.
During production of cartridges comprising a threaded connection, the core is supported at the end of the threaded connection, and the melt is injected into the mold from this end. However, in the case of nozzle cartridges, because of the long structural shape of the nozzle and because of the small diameter at the end of the nozzle, it would not be sufficient to support the core at the end of the nozzle to center the core in an exact manner during the injection process. Therefore, it has been tried to inject nozzle cartridges in one piece by providing two injection locations in the area of the annular shoulder. However, this is not a satisfactory solution to the problem of centering.
SUMMARY OF THE INVENTION
The invention is based on the objective to provide a method for producing a nozzle cartridge by injecting a melt into a mold, in which an exact centering of the mold core is ensured.
The invention proposes a method for producing a nozzle cartridge comprising a cylindrical cartridge body ending in an annular shoulder and a tapering nozzle projecting from the annular shoulder, by injecting a melt into a mold comprising a hollow mold and a core, the core or a part thereof being supported, in a first injection phase, on the hollow mold in a centering area at the transition between annular shoulder and nozzle by conically centered webs and the core, or a part thereof, being supported, in a filling-up phase, at a distance from the centering area to fill up the areas kept free by the webs during the injection phase.
In the method according to the invention, the core (or a part thereof) is pressed in the transitional area between the annular shoulder and the nozzle against centering webs of the hollow mold, and thereby the core is centered relatively to the hollow mold. From this transitional area, the nozzle part of the core projects forward. Thus, the area in which the core is supported is not located at the end of the core but in the area of the annular shoulder. At this location, the diameter of the core is relatively large, so that an exact centering by simple measures is possible. The core is supported to be centered by appropriate webs provided either at the core or at the hollow mold in the area of support. The melt coming from the nozzle passes between these webs towards the cartridge body. Initially, the webs cause interruptions to be produced at the annular shoulder of the cartridge. Therefore, it is only in the injection phase that the webs are held against a centering surface. Then the counterpressure supporting the core during the injection phase is terminated so that the core withdraws a short distance under the pressure of the melt and the webs obtain a distance from the centering surface. In this process, the annular shoulder of the cartridge is completed by further advancing the melt due to the pressure of the melt during a supplementary filling phase.
By the method according to the invention, it is achieved to produce a nozzle cartridge by centering the core in particular in the area of the annular shoulder (base of the nozzle) so that a complete centering exclusively at the extreme end of the cartridge is avoided.
The invention further refers to a device for producing a nozzle cartridge. In this device, the core consists of two parts. Namely, it consists of an interior core for the nozzle portion and an exterior core for the cartridge body. The interior core is controlled such that it rests against the hollow mold during the injection phase in a central area at the transition between annular shoulder and nozzle and maintains a distance from the hollow mold during a supplementary filling phase. Thus, in this context, the position of the exterior core remains unchanged during the injection phase. The interior core serves to center the exterior core and as a shaping tool for the nozzle area. The centering core is axially displaceable in the exterior core to be able to assume different positions.
Finally, the invention also refers to a nozzle cartridge with a cartridge body ending in an annular shoulder and a tapering closed nozzle projecting from the annular shoulder. According to the invention, a conical nozzle base reinforced by ribs is arranged in the transition portion between the annular shoulder and the nozzle. The nozzle base forms a conical transition portion with a sufficient thickness to form a steam lock for a sufficient storage time of the future charge. The ribs reinforce the transition, keeping the nozzle in position.
REFERENCES:
patent: 4452382 (1984-06-01), Von Holdt
patent: 4983344 (1991-01-01), Brown
patent: 5240397 (1993-08-01), Fay et al.
patent: 5762854 (1998-06-01), Valyi
Alfred Fischbach KG Kunststoff-Spritzgusswerk
Bui Thach H
Derakshani Philippe
Diller Ramik & Wight
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