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Plastic Injection Molding Machine Control

IP.com Disclosure Number: IPCOM000083427D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Rathke, JL: AUTHOR

Abstract

A two-stage plastic injection molding press includes a mold 5 with a mold cavity 6 and a mold cavity melt pressure sensor 7; an injection barrel 8 and an injection cylinder 9. A pump 10 supplies hydraulic fluid to hydraulic injection cylinder 9. A slide valve 11 is movable to the right to advance the ram 12, and to the left from the position illustrated to retract ram 12. The initial or injection pressure is provided by pump 10 as regulated by flow control valve 13, and the reduced secondary or holding pressure after cutover is established by actuation of valve 14. System control is provided by a controller 15, which may take the form of a hard-wired control unit or a sensor based data processor.

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Plastic Injection Molding Machine Control

A two-stage plastic injection molding press includes a mold 5 with a mold cavity 6 and a mold cavity melt pressure sensor 7; an injection barrel 8 and an injection cylinder 9. A pump 10 supplies hydraulic fluid to hydraulic injection cylinder 9. A slide valve 11 is movable to the right to advance the ram 12, and to the left from the position illustrated to retract ram 12. The initial or injection pressure is provided by pump 10 as regulated by flow control valve 13, and the reduced secondary or holding pressure after cutover is established by actuation of valve 14. System control is provided by a controller 15, which may take the form of a hard-wired control unit or a sensor based data processor.

To maintain part quality a cutover pressure at which controller 15 actuates valve 14 is set, and the time from the initiation of injection to hydraulic cutover or the signal to actuate valve 14, is monitored. If the time to cutover varies beyond an established tolerance, a viscosity correction is made by changing the melt temperature and/or the mold temperature. The melt temperature can be varied by altering the current to heating element 17 by a control, not shown, actuated upon a command from controller 15. As the time duration increases, the melt temperature is increased and as the time duration decreases, the melt temperature is decreased to stabilize the melt viscosity.

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