Temperature control of injection molding. Part I: Modeling and identification

Abstract

This paper develops a mathematical model for the dynamics of a plastic injection molding machine (IMM) that may be used for the design of a temperature-control system. The research in this paper is novel in comparison to others since the derived models explicitly include the effects of zone interaction and backpressure, and do not lump these into an arbitrary disturbance signal. A series of experiments were conducted on a 150-tonne IMM to identify the parameters of the proposed model using measurements of zone temperatures, percentage heater input, backpressure and screw speed. The identified model was validated using a series of blind tests that compared the model output with the measured barrel temperatures of the IMM.

Temperature control in injection molding. Part II: Controller design, simulation, and implementation

“…Zone interaction and back pressure are treated as hidden or unmeasurable disturbances in the overall control model. This is in contrast to the model developed in Part I of this paper (10).…”

“…Figure 1 illustrates an improved approach to model the interactions between zones in a pure sense. Details of this model were developed in Part I (10). In this model, the interaction is assumed to be a direct consequence of the difference in temperature between adjacent zones only.…”

“…Even though the MPC strategy has some degree of robustness to accommodate for model uncertainty, an accurate plant model is crucial for achieving high levels of performance in model-based control-system design. In this paper, we show that MPC may be applied to achieve better melt-temperature control when the model of the barrel heating process includes the effect of shear heating and zone interactions (10). The proposed MPC scheme incorporates the measurable disturbances as feed-forward inputs into the controller and therefore takes action before the actual temperature change occurs, thus achieving better control performance.…”

“…In Part I of the paper, a mathematical model for the temperature dynamics of a plastic injection molding machine was developed (10). The contribution of Part II is two-fold.…”

Instability of the Liquid Metal–Pattern Interface in the Lost Foam Casting of Aluminum Alloys

“…This equation was originally devised for a temperature range of 448 to 503 K (175 to 230°C) [25] but was subsequently shown to be applicable to a polystyrene melt at up to 703 K (430°C). [26] The mean temperature of the interface for which the viscosity was estimated was assumed to be the mean of the liquid metal and pattern temperatures, which was about 593 K (320°C).…”