Process analysis for control of injection molding.

摘要

This study developed some mathematical models that can be use by a rules based expert system to determine the effects of changes in some process variables that are being monitored by the expert system. It was assumed that the expert system that uses these models does not make any changes to machine settings and acts only as an advisor to the machine operator for making changes to correct the process.; The models were based on the assumptions that the molding machine being monitored is of an older vintage that does not have microprocessor control or linear positioning sensors for the clamp functions. Thus, the expert system would have access to only basic process information such as the state of limit switches and solenoids, temperatures (barrel, screw housing, hydraulic oil, mold cooling water, ambient), water flow rate through the mold, pressures (mold water in and out, melt plastic pressure, injection hydraulic pressure, and screw motor hydraulic pressure), and tierod bending stresses. Provisions in the models were made for machine options such as linear positioning on the screw and screw tachometer.; The models developed or used in this study include the following: (1) Viscosity model for the resin; (2) PVT model for the resin; (3) Model for hydraulic oil compressibility; (4) Model pump output as affected by pressure and temperature; (5) The Power Law Model for melt flow; (6) Models for pressure drop through a typical hydraulic system; (7) Model for residence time in the barrel; (8) Model for screw recovery time; (9) Model for melt transfer.; The models were developed assuming that the user of the expert system inputs in English units and has viscosity information only in the form of melt flow rate (MFR).