Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to evacuate mold or provide controlled environment
Reexamination Certificate
2000-12-29
2003-03-04
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to evacuate mold or provide controlled environment
C425S812000, C425SDIG001
Reexamination Certificate
active
06527538
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a method and apparatus for improving the manufacturing process for injection-molded optical discs such as a CD, CD-R, and a DVD, for example. More particularly, the invention relates to a method and apparatus for vacuum assisted venting of an injection mold used to manufacture optical discs.
Since the introduction of optical disc technology, the industry is experiencing phenomenal growth as the number of optical discs including CDS, CD ROMs and DVDs manufactured world-wide continues to increase. Naturally, such rapid growth has come with an associated set of technical problems relating to the high-volume manufacturing process used in producing optical discs. The sheer number of optical discs produced at many manufacturing plants coupled with the high production quotas have put a premium on optimizing plant equipment. Of particular concern to optical disc manufacturers is minimizing equipment downtime due to maintenance and repair.
The leading manufacturing method for producing optical discs continues to be the standard stamper-injection molding process or some variation of it. During the injection-molding process, a moldable material such as a polycarbonate-based thermoplastic is used to form the disc substrate. The moldable material is liquified by heating to a temperature sufficient to permit uniform flow into the mold cavity.
A certain amount of residual material and vapors are released during this process and it therefore becomes necessary to address its collection and disposal. Typically, the injection mold includes a variety of specially configured gaps or vents to provide an area for the vapors and residual material to collect. To prevent the molding process from being adversely effected, however, it is necessary to regularly clean the injection mold and remove the unwanted residual materials from the injection mold. Cleaning the injection mold is a time consuming and cumbersome process that typically involves substantial disassembly of the mold.
There have been many improvements to the injection molding process directed generally towards reducing equipment downtime due to routine maintenance and repairs. While these solutions have helped the injection molding process become more streamlined and cost-effective, they have not been successful in substantially reducing the need for frequent disassembly and cleaning of the injection mold itself.
As such, there is a need for an innovation in injection molding technology that is oriented towards eliminating the burdensome and time-consuming task of clearing residual material out of the vents in an injection mold.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for vacuum assisted venting of an injection mold that is designed to satisfy all of the aforementioned needs. It is particularly directed towards preventing the accumulation of residual material inside an injection mold and eliminates the need for the time-consuming and difficult task of disassembling the injection mold and removing accumulated residual material.
It is an object of this invention to provide a method and apparatus structured to minimize downtime in optical disc manufacturing equipment by eliminating the need to periodically disassemble an injection mold for purposes of clearing and removing accumulated residual material.
REFERENCES:
patent: 20 22 686 (1971-12-01), None
patent: 2 030 916 (1980-04-01), None
patent: 03 293107 (1991-12-01), None
patent: 05 342644 (1993-12-01), None
Bistran Joseph
Gensel Lewis
Mueller William
Pickutoski Edward
Fish & Neave
Heitbrink Tim
Jackson Robert R.
WEA Manufacturing Inc.
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