Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to work – Polymerizing – cross-linking – or curing
Reexamination Certificate
1997-09-24
2002-01-29
McDowell, Suzanne E. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to work
Polymerizing, cross-linking, or curing
C264S152000, C264S220000, C264S225000, C264S226000, C264S227000
Reexamination Certificate
active
06342178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for molding replicas such as automobile parts and household appliances. This invention also relates to an apparatus for molding such replicas.
2. Prior Art
In a process for developing a new model of automobile part or household appliance, a certain number of products must be produced for the purpose of confirming the outer appearance, shape and performance. To this end, various procedures were developed in the prior art. Among others, a procedure of producing a precision part replica using a mold of silicone rubber, known as a vacuum casting procedure, is widely used in the art. In this procedure, a pattern of molding serving as a master model is prepared from a suitable material such as wood, plastics and metals by manual modeling or by means of a machine tool (which can be controlled on the basis of three-dimensional CAD data). It was recently developed to produce a master model by an optical shaping system of irradiating a UV laser beam to a photo-curable resin in accordance with three-dimensional CAD data inputs.
In general, a replica is produced by burying the thus obtained master model in an addition/heat curable liquid silicone rubber composition, curing the silicone rubber composition, removing the master model, casting a thermosetting resin into the cavity in the cured silicone rubber where the master model has been removed, heating the thermosetting resin for curing. What is desired in the art is to produce such replicas within a short time. Attempts to meet such expectation have been made. For example, JP-A 114711/1991 discloses a method for producing a molded part by introducing a UV-curable liquid resin (epoxy or acrylic reactive resin) into a mold made of a transparent addition room temperature vulcanizable (RTV) silicone rubber composition, and irradiating UV to the liquid resin for curing. Combining these techniques, however, is far from satisfying the user's demand to test replicas within as short a time as possible from the design of a model shape.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to provide a method for molding a replica by forming a master model, forming a mother mold of silicone rubber on the basis of the master model, and casting a resin into the mold cavity to form a replica, the method being improved such that the replica can be briefly produced through a simple operation.
Another object of the invention is to provide an apparatus for molding a replica through a simple operation with ease.
We have found that when the mother mold is formed of a photo-curable liquid silicone rubber composition and a photo-curable liquid resin is used as the liquid resin to be filled in the mold cavity to produce the replica, quite unexpectedly, the photo-curable liquid resin filled in the mold cavity can be photo-cured by performing light irradiation from outside the mother mold formed of a transparent cured product of the photo-curable liquid silicone rubber composition. That is, the replica can be briefly produced through a simple operation.
Accordingly, according to a first aspect of the invention, there is provided a method for molding a replica, comprising the steps of
forming a mother mold from a transparent cured product of a photo-curable liquid silicone rubber composition, the mother mold having a cavity corresponding to the outer contour of an article to be duplicated,
filling the mold cavity with a photo-curable liquid resin, and
irradiating light to the photo-curable liquid resin from outside the mother mold, thereby curing the photo-curable liquid resin within the mother mold to produce a replica.
According to a second aspect of the invention, there is provided a method for molding a replica, comprising the steps of
(a) filling a container having at least one light-transmissive side surface with a photo-curable liquid silicone rubber composition, submerging a master model in the liquid silicone rubber composition, and irradiating light to the liquid silicone rubber composition to cure the composition to form a transparent silicone rubber part having the master model embedded therein,
(b) cutting the silicone rubber part into sections and removing the master model therefrom, the sections when mated constituting a silicone rubber mother mold having a cavity corresponding to the outer contour of the master model,
(c) mating the sections of the silicone rubber mother mold, filling the cavity with a photo-curable liquid resin, and irradiating light to the photo-curable liquid resin from outside the mother mold, thereby curing the photo-curable liquid resin within the mother mold to produce a replica,
(d) removing the replica from the silicone rubber mother mold.
According to a third aspect of the invention, there is provided an apparatus for molding a replica comprising
a mother mold having a cavity corresponding to the outer contour of an article to be duplicated, said mother mold being formed from a transparent cured product of a photo-curable composition,
a means for casting or filling the mold cavity with a photo-curable liquid resin, and
a means for irradiating light to the photo-curable liquid resin from outside the mother mold thereby curing the photo-curable resin.
The master model is advantageously produced by an optical shaping process of irradiating light to a photo-curable liquid resin composition in accordance with CAD data inputs regarding the shape and dimensions of the master model designed by three-dimensional CAD technique, thereby curing the resin composition.
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Anai Kousi
Fujiki Hironao
Kita Tarou
Matsuoka Yasuhiko
Nakamura Shohei
Asahi Kasei Kabushiki Kaisha
McDowell Suzanne E.
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