Plastic article or earthenware shaping or treating: apparatus – Sets of male-female press molds – Traveling female mold
Patent
1996-05-13
1998-07-28
Davis, Robert
Plastic article or earthenware shaping or treating: apparatus
Sets of male-female press molds
Traveling female mold
425407, 425422, 425423, 425438, 425809, B29C 4308, B29C 4342
Patent
active
057860793
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for manufacturing items made of plastics, particularly screw closures, by pressure molding.
Methods and devices for the pressure molding of closures constituted by a cup to be applied by screwing (screw caps) or by pressure (crown caps) on the mouth of containers are already known, for example from German publication no. 2,007,777, from European publication no. 162,456, and from U.S. Pat. Nos. 2,155,316, 2,891,281, 4,343,754, and 4,497,765.
Conventional devices comprise a carousel that can rotate about a vertical axis and on which a plurality of molding units, mutually spaced by the same angle, are mounted. Each unit comprises an upper male half-mold that is aligned with a lower female half-mold. A dose of semi-fluid plastic material is introduced in the female half-mold and is pressed by means of a relative motion of the two half-molds. In U.S. prior Pat. No. 2,155,316 and U.S. Pat. No. 2,891,281 (hereinafter referenced as prior patents X), the relative motion is produced by the hydraulic lifting of the female half-mold, whereas in the other prior patents (hereinafter termed prior patents Y) it is the male half-mold that is forced against the female half-mold by virtue of a mechanical movement produced by cam means.
In the devices disclosed in prior patents X it is not possible to produce screw closures provided with a tamper-proof ring. On the other hand, in the devices disclosed in prior patents Y, in order to allow the formation of the tamper-proof ring, the male half-mold has a composite structure, in which the elements must be movable in order to be able to transmit the molding pressure and allow to remove the molded closure. Due to this reason, in devices disclosed in prior patents Y, the high stresses that occur during molding require the male half-molds to have a particularly strong structure to neutralize the unavoidable deformations and mechanical tolerances that might compromise their perfect mating with the female half-molds. Furthermore, actuation elements are required to open the part of the mold that is meant to form the tamper-proof ring. This strong and complex structure, however, makes replacement and calibration of the half-molds very difficult, especially when it is necessary to replace said half-molds to manufacture closures having a different shape.
SUMMARY OF THE INVENTION
The principal aim of the present invention is to provide an apparatus for producing screw caps with a tamper-proof ring, in which the pressing effect is assigned to the female half-mold, as in prior patents X, but the male half-mold is structured so as to allow to form the tamper-proof ring as in prior patents Y.
Within the scope of this aim, an object of the present invention is to provide an apparatus in which the half-molds can be easily replaced in relation to the characteristics of the closures to be manufactured.
This aim and this object are achieved with an apparatus whose characteristics are defined in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Further particularities of the present invention will become apparent from the following description of a preferred embodiment and of some variations, illustrated only by way of non-limitative example in the accompanying drawings, wherein:
FIG. 1 is a sectional elevation view of a molding unit, taken along a vertical plane, for forming a closure with a tamper-proof ring;
FIGS. 2 and 3 are two enlarged-scale views of details of FIG. 1;
FIGS. 4, 5, 6, and 7 are views of further operating situations of the apparatus;
FIG. 8 is a sectional view of another type of closure;
FIG. 9 is a view of another embodiment of the mold for manufacturing the closure of FIG. 8;
FIG. 10 is a view of a further embodiment of the mold;
FIG. 11 is a view of still another embodiment, related to the means for expelling the molded closure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to FIGS. 1-3, the apparatus is composed of a carousel that can rotate about a vertical axis and supports,
REFERENCES:
patent: 2440366 (1948-04-01), Cropp
patent: 2891281 (1959-06-01), Heinzelman
patent: 4640673 (1987-02-01), Takeda et al.
patent: 4776782 (1988-10-01), Murayama et al.
patent: 4819906 (1989-04-01), Cochrane
patent: 5451360 (1995-09-01), Ingram
patent: 5554327 (1996-09-01), Ingram et al.
Davis Robert
Josif Albert
Modiano Guido
Sacmi Cooperativa Meccanici Imola S.c.r.l.
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