Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With product ejector
Reexamination Certificate
2000-05-16
2001-09-18
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With product ejector
C249S158000, C425S572000, C425S576000
Reexamination Certificate
active
06290486
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for making plastic articles, especially wine corks, from plastic resin in a continuous and efficient operation.
Articles such as wine corks as well as others are made using a plastic resin which contains a blowing agent such that after injection of the resin into a mold cavity gas bubbles are formed in the plastic resin. The plastic resin expands in volume as the mold cavity volume is allowed to expand.
Plastic wine corks are particularly useful as they represent an alternative to cork for sealing wine bottles. These and other articles may be prepared by the process described above which is termed “foam molding”. This process and apparatus requires that the mold cavity can expand to allow gas bubbles to form in the resin as it cools.
Unfortunately, however, this procedure takes a substantial amount of time as cooling a relatively thick part, particularly a relatively thick part that contains gas bubbles therein, is inherently slow especially due to the very poor thermal transmission properties of the gas filled plastic.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide an efficient and expeditious process and apparatus for preparing relatively thick plastic parts containing gas therein.
Another object of the present invention is to provide a process and apparatus as aforesaid for efficiently and expeditiously preparing such relatively thick plastic parts, as plastic wine corks.
A further object of the present invention is to provide a process and apparatus as aforesaid that separates the cooling phase of the molding cycle from the remainder of the cycle allowing the operation to be more effectively performed.
The present invention performs the molding operation in a first state of the cycle. Subsequent stages permit mold cavity expansion, article cooling and article expansion while at the same time permitting the molding of further articles. The final stage of the cycle is the ejection of the cooled and expanded article.
Thus, the present invention efficiently permits the continuous formation of additional articles while the initially formed article or articles continue their processing steps, as by cooling, expansion and ejection.
Thus, the present invention comprises a process for preparing a molded article, as for example wine corks, which comprises: filling a first mold cavity via a feeding unit in engagement with said first mold cavity with plastic containing a volume expanding agent; moving the filled first mold cavity and feeding unit away from each other, moving a second mold cavity and said feeding unit into engagement with each other and filling said second mold cavity via said feeding unit with plastic containing a volume expanding agent; expanding said plastic in said first mold cavity via said volume expanding agent while said second mold cavity is in engagement with said feeding unit; and ejecting the expanded article from the first mold cavity.
The present invention also comprises an apparatus for forming a molded article, which comprises: first and second mold cavities spaced from each other for forming molded articles; a feeding unit for separately feeding plastic containing a volume expanding agent into said first and second mold cavities; means for separately moving said first and second mold cavities and said feeding unit into and out of engagement with each other; wherein said plastic is expanded in said first mold cavity via said volume expanding agent while said second mold cavity is in engagement with said feeding unit; and means for ejecting the expanded article from the first mold cavity.
Further features of the present invention will appear hereinbelow.
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Bachman & LaPointe P.C.
Husky Injection Molding Systems Ltd.
Luk Emmanuel S.
Nguyen Nam
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