Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Positioning of a mold part to form a cavity or controlling...
Patent
1989-05-18
1991-05-14
Heitbrink, Jill L.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Positioning of a mold part to form a cavity or controlling...
264 22, 2642972, 2643287, 26432811, 425141, 425150, 425555, 425575, B29C 4556
Patent
active
050154265
ABSTRACT:
In critical surface quality plastic molded articles, especially in optical lenses and disks, an "adaptive" mold cavity is used to automatically control melt pressure and densification during mold packing to within a predetermined range of acceptable values, while normal cycle-to-cycle molding process variations produce a corresponding minor but acceptable change in the molded-part thickness. In multicavity "adaptive" moldsets, permissible cavity-to-cavity imbalance without an overfilled cavity flashing at the parting line is increased. A resilient member (mechanical steel spring or elastomer or hydraulic cylinder) is interposed between the part-forming mold insert surface and the associated clamp plate for that half of the moldset. When the mold is initially closed, a separation distance between the A and B mold insert is less than the molded product specification's minimum acceptable part thickness. Sufficient volume of injected plastic melt must enter the adaptive mold cavity to cause at least some minimum spring deflection, and thus assure that the resulting molded-part thickness will be somewhere between minimum and maximum thickness tolerances. At maximum acceptable volume of the injected melt, the resilient member is still incompletely compressed. This A-B mold insert second separation distance must also be less than or equal to the maximum acceptable molded-part thickness. The adaptive cavity's proper self-adjusting performance may be verified by an LVDT.
REFERENCES:
patent: 2443826 (1948-06-01), Johnson
patent: 4573903 (1986-03-01), Boudet et al.
patent: 4715804 (1987-12-01), Takahashi
patent: 4767579 (1988-08-01), Buja et al.
patent: 4881884 (1989-11-01), De'Ath
Society of Plastics Engineers ANTEC '88 published paper entitled: "Transfer Point Control Comparison Between Mold Parting Line and Standard Strategies", by J. Wenskus of Eastman Kodak.
Society of Plastics Engineers ANTEC '88 published paper entitled: "PC-Based Monitoring of Melt State Variables for Predicting Injection Molded Part Quality" by Applicants.
Society of Manufacturing Engineers 1986 published paper entitled: "Intelligent Molds for Automatic Injection Molding" by R. Groleau of Transal.
Galic George J.
Maus Steven M.
Galic Maus Ventures
Heitbrink Jill L.
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