TPT July 2007

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Plastic & C omposite Tube: Products & Manufacture
92 July /August 2007
As a response to increasing resin prices
and the demand for more functional pipes,
Battenfeld Extrusionstechnik, Germany,
has developed an innovative side-fed multi-
layer die. The die allows the processing
of materials with high residence time and
temperatures, even at low mass flow rates,
and ensures an accurate wall thickness
distribution.
In-demand plastic pipe attributes, such as
acoustic insulation, oxygen barrier, and
special optical, mechanical or thermal
properties, can be achieved in multi-layer
products consisting
of special materials
that fulfil different
functions.
Such materials,
however, are often
highly sensitive
to thermal and
mechanical stress
and, compared with
basic materials,
require special
process parameters.
With conventional die
concepts, such as
spiral mandrel dies,
these materials can
be processed only
with difficulty, if at all.
Developed using CFD-based flow
simulation, Battenfeld Extrusionstechnik’s
new side-fed die allows – by non-centrical
melt injection – a quick and optimal melt
distribution into a circular ring geometry for
further distribution.
A geometry of twin centre sleeves preceded
by a coathanger manifold ensures
symmetrical distribution of pressure
inside the die. This causes the majority of
mechanical forces generated to cancel
each other out, and ensures automatic
centring of the mandrel.
The design includes the option of modular,
consecutive connection of several
distributors, and thus a facility for thermal
isolation of each individual layer of melt
from the other layers. To further optimise
melt homogeneity, the side-fed distributor is
followed by a brake-up plate, the geometry
of which has also been optimised using 3D
flow simulation.
Battenfeld Extrusionstechnik GmbH
– Germany
Fax : +49 5731 27 124
Email:
Website:
High-precision manufacturing of multi-layer pipes
fi The new twin centre sleeves (with break-up plate) from Battenfeld
Extrusionstechnik