Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Patent
1995-08-28
1998-01-13
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
264153, 264265, 264266, 425112, 425122, 4251261, 4251291, 425292, 4253021, 4253051, B29C 4514, B29C 4516
Patent
active
057075816
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus and method for producing patterned molded articles to be used for front panels or buttons of audio-visual equipment, dashboards or buttons of automobiles, and the like.
BACKGROUND ART
Conventionally available apparatuses for producing patterned molded articles are classified into (1) so-called sheet-feed type injection molding and simultaneously patterning apparatuses and (2) so-called continuous type injection molding and simultaneously patterning apparatuses.
A sheet-feed type injection molding and simultaneously patterning apparatus of the former type (1) comprises an injection mold provided with a female mold having a recess and a male mold having a projection, and a clamp means for pressing a pattern film against a periphery of the recess of the female mold.
The method for producing patterned molded articles by using this apparatus comprises the following steps. First, a sheet-like pattern film is pressed against the periphery of the recess of the female mold by the clamp means. Then, the pattern film is put into close contact with the inner surface of the recess of the female mold by vacuum suction. In this state, with the female mold and the male mold closed, molten resin is injected, followed by mold opening, whereby a patterned molded article in which a pattern film is formed on the surface of the injection-molded product is obtained.
On the other hand, a continuous type injection molding and simultaneously patterning apparatus of the latter type (2) is one in which an apparatus for producing injection molded articles similar to the apparatus of the type (1) further comprises a first roll for continuously unwinding a pattern film to feed it to an injection mold, and a second roll for winding up the unwound pattern film.
The method for producing patterned molded articles by using this apparatus comprises the following steps. First, a continuity of pattern film from the first roll to the second roll is fed into the injection mold, where only necessary portions of the pattern film are cut out and pressed against the periphery of the recess of the female mold by the clamp means. Then, the pattern film is put into close contact with the recess of the female mold by vacuum suction. In this state, with the female mold and the male mold closed, molten resin is injected, followed by mold opening, whereby a patterned molded article in which a pattern film is formed on the surface of the injection-molded product is obtained, while the pattern film whose necessary portions have been cut out is wound up by the second roll.
However, the conventional apparatuses have had the following disadvantages.
In the type (1) apparatus, since pattern films cut into sheets are used, it is impossible to keep a certain level of tension applied to the entire surface of the pattern film before pressing the pattern film against the female mold by the clamp means. On this account, when the pattern film, after being pressed against the female mold by the clamp means, is vacuum-sucked into close contact with the inner surface of the recess of the female mold, the pattern film cannot be stretched uniformly over its entire surface, so that the pattern film with wrinkles and twists is put into close contact with the inner surface of the recess of the female mold. As a result, the pattern cannot be formed clearly on the surface of the injection molded article.
In the type (2) apparatus, on the other hand, since the pattern film is unwound from the first roll and wound up by the second roll, only necessary portions of the pattern film (four portions of the pattern film, i.e., upstream portion, downstream portion, and both side portions) must be cut out in such a way that the continuity of pattern film is not cut off. On this account, cutout chips are generated in such a large quantity that they cannot be fully prevented from entering the injection mold. Therefore, the resulting products are injection molded articles with cutout chips deposited, causing the rate of non-def
REFERENCES:
patent: 4269579 (1981-05-01), Thomas
patent: 5188787 (1993-02-01), King et al.
Patent Abstracts of Japan, vol. 016, No. 293 (M-1273), 29 Jun. 1992 & JP-A-04 080008 (Dainippon Printing Co. Ltd.), 13 Mar. 1992, *abstract*.
Patent Abstracts of Japan, vol. 011, No. 356 (M-644), 20 Nov. 1987 & JP-A-62 134231 (Showa Denko KK), 17 Jun. 1987, *abstract*.
Nissha Printing Co. Ltd.
Tentoni Leo B.
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