PROFIBUS DP controls blow-moulding machines (Germany)

Round and square shaped PET-bottles as well as more complex and asymmetric containers were to be produced by seven different types of (ADS) blow-moulding machines which have been designed to comply with the same modular layout.

All machines use the same PROFIBUS DP control system. Up to seven participants, i. e. three (TWK) multiturn absolute shaft encoders, one frequency converter and several heating units are connected to an Siemens-S7 control unit. Two encoders are used as feedback devices during the transportation of the blank forms and of the final products. Another encoder coupled to a cable-spring converter controls the movement of the blast pipes when they are lowered into the mould cavities.

PROFIBUS DP along with S7-control units and TWK encoders have been chosen to allow maximum flexibility when the machines must be adapted to different shapes and volumes of bottles. Depending on the type of machine the output frequency ranges from 2000 to 8000 units per hour. Containers with capacities of 0.2 liter up to 10 liter can be produced.