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Process control and monitoring system

The process control consists firstly of the monitoring of dynamic heating and cooling processes.

Monitoring tests with the modular plate mould in the heating up and cooling phase were carried out successfully on the 200 ton lab system with several thermoplastic resins.

Before start of injection, the fast heating phase is started. This resulted in heating up times from 70° C up to 160 ° C in app. 120 seconds. Simultaneously with start of the cooling phase of the 200 ton lab system, the fast cooling phase of the unit started. The cycle is completed after app.180 seconds at 70° C. The monitoring tests show the high applicability of the dynamic device for the process optimisation with JETex and HTex mould technology. The on-line temperature monitor is part of the enhanced process control of the project.

The main applications are:
- On-line monitoring of mould temperature;
- Determination of cycle time;
- Temperature of hot circuit;
- Temperature of cold circuit;
- Flow rate;
- Energy balance measurements;
- Possibility of heat exchange between the cold and hot circuit (recovery of energy).

The on-line monitor is a temperature monitoring unit to be used for consolidation analysis of the materials used with the JETex process. The modular plate mould was used during the injection phase. The tests were successfully completed on the 200 ton lab system with several thermoplastic resins.

The monitor prototype consists of two computer systems which are working in parallel during the processing cycle. One system is capable of writing processing data shot by shot on a hard disk. Machine data like the injection piston movements during the mould filling phase, the hydraulic pressure, injection speed and the mould temperature can be processed and used for analysis. The data are shown on-line on a screen as shown in the following pictures.

The second computer gets ultrasound data directly from the mould and pressure and temperature signals from the first computer. This data can be used to analyse the processing phase quite sensitive, because the ultrasound signal changes its amplitude during the consolidating phase of the resin. If gas is injected into the resin to form a hollow bubble in the centre of the part, the ultrasound gives a clear signal change when the gas passes the ultrasound sensor. So, all signal changes indicate significant steps of the injection and consolidating phase and can therefore be used for quality analysis and quality assurance measures.

The Monitoring system was successfully set-up and functionally tested. Start of systematic processing studies is planned during the second project year in combination with the processing control of dynamic heating.

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