Purpose of the batch Pre-expander is to expand a prefixed quantity of raw material to obtain beads of expanded EPS having the programmed average density.
The machine is composed by:
- Raw material loading hopper.
- Batching system equipped with balance to weigh the right quantity of raw material to put into the expansion chamber.
- Expansion chamber raw material fast loading system made by screw.
- Expansion chamber made in stainless steel, AISI 304 type, with cylindrical shape on the upper side and frustum of cone shape on the bottom side. This special peculiarity allows to realize a more progressive bead expansion and to achieve a better density uniformity.
- Agitator shaft, stainless steel made, AISI 304 type, driven by an electronic speed control system to have the possibility to optimize the rotation speed depending on the phase of cycle, on the type of raw material and on the expansion’s conditions inside the chamber.
- An automatic density check device monitors every single expansion cycle to have perfect repeatability.
- Fluidized bed dryer stainless steel made, to dry the expanded material outgoing from the expansion room. The bed is complete of steam-air heat exchanger to avoid the beads thermal shock.
- Fan with rotary valve to send the material to the seasoning silos.
- Second expansion system.
- Computerized electronic control board.
The machine is controlled by a Siemens PLC; the man-machine interface is realized by a Touch panel where is possible to select and store all the working parameters.
The air and steam inlets are automatically adjusted in quantity and temperature during all the expansion phases.
The machine has been designed to do an easy maintenance and to have the possibility to replace easily any component.