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The meter used is the gear type with encoder. The speed of the additive pump is adjustable with a standard analogue signal 0-10V. The speed of the extrusion line is given by a standard analogue signal 0-10V.
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In a system made up of 3 plastic film extrusion lines (the illustration shows just one of the 3 lines), the quantity of hot additive to be mixed with the PVC to be extruded had to be controlled, bearing in mind the quantity set by the operator and the extrusion speed. For reasons of precision, the amount of additive really dispensed also had to be controlled, compensating the speed of the pump and managing any flow alarms if compensation was not possible. Alarms from the extrusion line and from the additive containment tank also had to be managed, displaying all the anomalies and operating options on the operator panel. The meter used is the gear type with encoder. The speed of the additive pump is adjustable with a standard analogue signal 0-10V. The speed of the extrusion line is given by a standard analogue signal 0-10V. Solution: the system was fulfilled using an electronic section repeated for each of the 3 extrusion lines. Each section consists of an MC-PLC board, combined with an interface with analogue output 0-10V, capable of managing the line and controlling all the signals. The speed of the pump is set considering the data bound to the speed of the extrusion line and the quantity of additive requested and obtaining the rpm from the graph « Flow dispensed = f (rotation speed) « related to the pump, saved in the MC-PLC board. While the system operates, any differences between the theoretic quantity of additive and that really dispensed are compensated by increasing or reducing the rotation speed of the pump. The use of the serial line RS485, suitable for managing a network, enabled the 3 lines to be centralized in one single operator panel. The MC-PLC board, thanks to its numerous peripheral points and its large memory, is able to economically resolve many problems which would be difficult to resolve with other systems.
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In a system made up of 3 plastic film extrusion lines (the illustration shows just one of the 3 lines), the quantity of hot additive to be mixed with the PVC to be extruded had to be controlled, bearing in mind the quantity set by the operator and the extrusion speed. For reasons of precision, the amount of additive really dispensed also had to be controlled, compensating the speed of the pump and managing any flow alarms if compensation was not possible. Alarms from the extrusion line and from the additive containment tank also had to be managed, displaying all the anomalies and operating options on the operator panel. The meter used is the gear type with encoder. The speed of the additive pump is adjustable with a standard analogue signal 0-10V. The speed of the extrusion line is given by a standard analogue signal 0-10V. Solution: the system was fulfilled using an electronic section repeated for each of the 3 extrusion lines. Each section consists of an MC-PLC board, combined with an interface with analogue output 0-10V, capable of managing the line and controlling all the signals. The speed of the pump is set considering the data bound to the speed of the extrusion line and the quantity of additive requested and obtaining the rpm from the graph „Flow dispensed = f (rotation speed) „related to the pump, saved in the MC-PLC board. While the system operates, any differences between the theoretic quantity of additive and that really dispensed are compensated by increasing or reducing the rotation speed of the pump. The use of the serial line RS485, suitable for managing a network, enabled the 3 lines to be centralized in one single operator panel. The MC-PLC board, thanks to its numerous peripheral points and its large memory, is able to economically resolve many problems which would be difficult to resolve with other systems.
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In un sistema composto da 3 linee di estrusione di film plastico (nella figura è riportata solo una delle 3 linee), era necessario effettuare un controllo in grado di dosare la quantità di additivo caldo da miscelare al PVC da estrudere tenendo in considerazione la quantità impostata dall’operatore e la velocità di estrusione. Per motivi di precisione era richiesto anche il controllo dell’additivo effettivamente erogato, con compensazione della velocità della pompa e con la gestione degli eventuali allarmi di flusso qualora la compensazione non fosse possibile. Era inoltre richiesta la gestione degli allarmi provenienti dalla linea di estrusione e dalla vasca contenente l’additivo, con visualizzazione di tutte le anomalie e le opzioni di funzionamento sul pannello operatore. Il misuratore usato è del tipo ad ingranaggi con encoder. La velocità della pompa dell’additivo è regolabile con un segnale analogico standard 0-10V. La velocità della linea di estrusione è data da un segnale analogico standard 0-10V. Soluzione: il sistema è stato realizzato utilizzando una sezione elettronica ripetuta per ognuna delle 3 linee di estrusione. Ogni sezione è formata da una scheda MC-PLC, abbinata ad un’interfaccia con uscita analogica 0-10V, in grado di gestire la linea, controllandone tutti i segnali. La velocità della pompa viene impostata considerando i dati legati alla velocità della linea di estrusione e alla quantità di additivo richiesto e ricavando il numero di giri/minuto dal grafico ” Flusso erogato = f(Velocità di rotazione) ” relativo alla pompa, memorizzato all’interno della scheda MC-PLC. Durante il funzionamento del sistema, eventuali differenze fra la quantità teorica di additivo e quella effettivamente erogata, vengono compensate aumentando o diminuendo la velocità di rotazione della pompa. L’impiego della linea seriale RS485, adatta alla gestione di una rete, ha permesso la centralizzazione delle 3 linee in un unico pannello operatore. La scheda MC-PLC, grazie alle numerose periferiche e all’elevata quantità di memoria di cui è dotata, è in grado di risolvere, in modo economico numerose problematiche, difficilmente risolvibili con altri sistemi.
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