Injection molding apparatus control system and method of injection

Abstract

There is shown an injection molding apparatus, which comprises a source of a fluid molding material and a molding die into which the molding material is forced under pressure. The apparatus includes a control means for initiating and controlling an injection cycle in which the fluid molding material is injected into the molding die in a particular and predetermined manner. The control means generally comprises a programmable logic controller (PLC) which is programmed to receive signals from sensors adapted to sense variable parameters of the injection cycle. The PLC is programmed to generate control signals based upon the signals from the sensors so as to control the variable parameters of the injection cycle. The output control signals of the PLC are coupled through an interface circuit to a servo-control circuit which in turn is operatively coupled to control various parameters of the injection cycle. The control system allows the user to pre-set multiple flow rates to accomplish desired acceleration/deceleration characteristics during the injection cycle so as to optimize fabrication of high quality patterns while reducing scrap patterns. The control system may also be implemented to prevent a machine operator from making unauthorized changes of injection parameters to assure the integrity of injection parameters on a continuous basis. The use of a high level PLC also enables generation and collection of data relevant to the injection processes to visually monitor the process dynamic parameters, to display an injection profile with tolerances, to facilitate diagnostics as well as other valuable functions.