Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,... – Simultaneous severing and shaping – or severing while work...
Patent
1994-08-26
1998-09-01
Dixon, Merrick
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
Simultaneous severing and shaping, or severing while work...
264 405, 264294, 2643281, 26432816, 425149, 425292, 425590, 425595, B28B 714
Patent
active
058007598
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an insert molded article to be used as front panels or buttons of AV (audio-visual) devices or instrument panels of automobiles, and an apparatus and a method for producing the insert molded article.
BACKGROUND ART
There have been employed such apparatuses and methods (1) as disclosed in Japanese Laid-Open Patent Publication Nos. 57-102328 (102328/1982), 59-202834 (202834/1984) and such apparatuses and methods (2) as disclosed in Japanese Laid-Open Patent Publication No. 63-25012 (25012/1988) to obtain insert molded articles.
According to the apparatus and method (1) above, a patterned insert material of a preformed plastic film is set in a female die of an injection molding die for an insert molded article. An unnecessary portion of the patterned insert material is cut within the injection molding die.
According to the apparatus and method (2), meanwhile, the apparatus consists of a pair of dies defining a cavity in the shape of a to-be-formed product, a cutting means for operating to cut a blank from a long insert film, and a transferring means for supplying the blank from the cutting means to the pair of dies and then setting the blank in the cavity in preparation for a molding process. After the long insert film is cut to a suitable length by the cutting means of the apparatus, notches are formed in the film, to thereby form a blank with a flange in development. Then, the blank is fed and introduced into the completely prepared dies by the transferring means, and then the die clamping and insert molding are performed. The blank is introduced in the dies while the blank is flat without being preformed at this time. The introduced blank is once brought in tight contact with the male die to bend the flange for a preforming process. After the dies are clamped, the preformed blank is pressed from the male die to the female die by the pressure of molding resin injected from the male die.
The above-described conventional apparatus and methods have some drawbacks as follows.
In the arrangement (1), since the unnecessary portion of the patterned insert material is cut and removed by utilizing the edges of the male and female dies in the injection molding die, the film refuse produced in the cutting of the insert material is accumulated and becomes a hard lump in the periphery of the edges of the dies, so that the surface of each die in the periphery of the edge is damaged by the lump. The dies are accordingly required to be frequently exchanged, which increases maintenance costs. The film refuse also adheres to the surface of the patterned insert material or the surfaces of the dies, and mingles with the molding resin. As a result, the film refuse is adhered to the surface of an insert molded article and the number of defective articles is increased.
The molding resin is injected from either one of the male and female dies of the injection molding die. Therefore, the male and female dies are heated at different temperatures, showing different expansion coefficients. It is hence difficult to maintain the distance between the edges of the male and female dies constant at all times. When the edges of both dies core too close, the edges are broken. If the edges are separated by too much distance, the insert material is not properly cut, thereby raising the costs of the dies and film.
In the arrangement (2), the insert film is notched and trimmed to have the flange in development to agree with a recessed surface of the female die forming the cavity of the injection molding die. If a three-dimensional, smooth and curved insert molded article, e.g., a round bowl is to be formed, the notch should be correctly cut in the insert film so as to avoid leakage of the molten molding resin from the joint of the flange of the blank. This requires a large amount of labor and time, and therefore is not practical. Since the joint of the flange is present, the joint is exposed on the surface of the molded article, degrading the aesthetic design of the finished article.
Furthermor
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Okuno Shiroh
Yamazaki Seiichi
Dixon Merrick
Nissha Printing Co. Ltd.
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