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
1995-08-24
2001-05-15
Pyon, Harold (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
C425S013000, C425S127000, C425S129100, C425S812000, C118S256000, C118S410000, C427S096400, C427S097100
Reexamination Certificate
active
06231333
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to injection molding, and, more specifically, to vacuum initiated injection molding of solder or plastic for example.
Standard injection molding uses positive pressure to force a liquid with low viscosity into mold cavities. The injected liquid displaces the gas or air in the mold cavities and is then allowed to solidify for forming the desired molded article. If the mold cavity is large, or if the cavity is open at two places, then displaced gas can easily flow out a vent. However, a tiny cavity with a single opening, or blind hole, presents special difficulties. For solder molding when the cavity diameter is quite small, such as 10-750 microns, then it is very difficult or impractical to include a vent. This is especially true in a array of mold cavities with cavity separation as small as about 75 microns. Such blind hole mold cavities will trap gas therein preventing complete filling of the cavity with the injected liquid resulting in defective molded articles. And, since the injection pressure exceeds ambient or atmospheric pressure, undesirable leakage of the injected liquid in the injection apparatus may occur.
Vacuum casting and vacuum-initiated blow-molding solve some of these problems. However, these methods typically require sophisticated valves and are limited as to mold sizes and types. The molds are typically injected one at a time in a sequential process which seals the liquid reservoir to each mold cavity in turn. After a temporary seal is made, valves sequentially introduce vacuum and liquid into the mold cavity.
SUMMARY OF THE INVENTION
An apparatus and method utilize vacuum injected molding of a liquid in a plurality of mold cells for solidification therein. An injection head includes spaced apart vacuum and injection slots positionable atop a mold plate in flow communication with the mold cells therein. Relative axial sliding is effected between the injection head and the mold plate for sequentially evacuating gas from the mold cells using a continuous vacuum followed in turn by sequentially injecting into the evacuated mold cells the liquid from a continuous source thereof. Sliding of the injection head over the mold plate automatically provides self valving for sequentially evacuating and filling the mold cells from the same side of the mold plate. In a preferred embodiment, the vacuum and injection slots are linked together at the mold plate so that surface tension of the liquid restrains flow of the liquid from the injection slots to the vacuum slot while allowing gas flow therebetween for effecting the vacuum in the mold cells.
REFERENCES:
patent: 3470848 (1969-10-01), Dreher
patent: 3735729 (1973-05-01), Bird
patent: 3749053 (1973-07-01), Timson
patent: 3797281 (1974-03-01), Norton
patent: 3996885 (1976-12-01), Jackson et al.
patent: 4140470 (1979-02-01), Pasch et al.
patent: 4146081 (1979-03-01), Reis
patent: 4572103 (1986-02-01), Engel
patent: 4934309 (1990-06-01), Ledermann et al.
patent: 4959246 (1990-09-01), Cleempat
patent: 4961955 (1990-10-01), Goldberg
patent: 4968534 (1990-11-01), Bogardy
patent: 4982777 (1991-01-01), Chandley
patent: 5059112 (1991-10-01), Wieser
patent: 5238176 (1993-08-01), Nishimura
patent: 5244143 (1993-09-01), Ference et al.
patent: 5303762 (1994-04-01), Chandley
Middleman, S. “Fundamentals of Polymer Processing” p. 260-261, 1997.
Ference Thomas George
Gruber Peter Alfred
Hernandez Bernie
Kummer Egon Max
Zingher Arthur Richard
Conte Francis L.
International Business Machines - Corporation
Pyon Harold
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