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Injection Molding Control

IP.com Disclosure Number: IPCOM000084947D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Grimes, DW: AUTHOR [+2]

Abstract

A common mode of plastic injection molding uses a two-stage injection press, wherein a high primary injection pressure is used to fill the mold followed by a reduced secondary holding pressure. The staging of the press or hydraulic cutover between injection and holding pressure may be accomplished, using material cavity pressure which is compared to a reference value.

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Injection Molding Control

A common mode of plastic injection molding uses a two-stage injection press, wherein a high primary injection pressure is used to fill the mold followed by a reduced secondary holding pressure. The staging of the press or hydraulic cutover between injection and holding pressure may be accomplished, using material cavity pressure which is compared to a reference value.

As shown in the figure, a power supply 10 supplies a DC excitation voltage to the strain gauge bridge 11 which is used to measure the cavity pressure. Amplifier 12 is used to amplify and balance the millivolt output signal of bridge 11 to a level compatible with the input requirements of comparison circuit 14.

The generation of a reference value is accomplished by a current output station (COS) 15 which is a nonisolated analog memory, the value of which can be changed locally by integration of a DC level selected by increase or decrease push buttons or remotely by application of an analog voltage and digital selection. A mode switch set to either manual or nonmanual mode disallows remote or local value adjustments, respectively.

Comparator 14 receives as inputs, the outputs of amplifier 12 and COS 15. When the output of amplifier 12 exceeds the output of COS 15, an output issues on line 16 that selects a relay to effect the hydraulic cutover or reduction of pressure from injection to hold. The comparator 14 latches in such relay select state until the end of the molding mac...