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Bitruder: Modules
1 Drive unit
| The drive
unit consists of a powerful, low-noise
housing with integrated torque divider
and thrust bearing in the cast housing.
Different design versions are available,
due to the various plasticising systems.
In the conical system, two tapered
pinions serve as torque divider. Single
axial cylinder roller bearings are used
as thrust bearings. In cylindrical
systems, on the other hand, the torque
divider consists of a multi-shaft
distributor gearbox. For the thrust
bearing, one single and one multiple
axial cylinder roller bearing (tandem
bearing) are used. The drive can be
supplied in AC or DC technology, as
desired. |
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2 Dosing unit
| Twin-screw
extruders are equipped with a feed
hopper or dosing unit respectively,
depending on customer requests. By using
a volumetric or gravimetric dosing unit,
the range of options for the respective
formulation is dramatically increased.
The gravimetric dosing unit additionally
permits continuous weighing of the raw
materials and a constant metre weight. |
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3. Temperature control
| Barrels are
divided into heating and cooling zones
according to the process technology of
the individual barrel or screw section
and their respective plasticising
functions. This guarantees a precise
temperature profile across the entire
length of the barrel. Usually air
cooling is used. Other cooling media is
only used in the case of machines with
exceptionally high throughput rates or
machines that process extremely adherent
components. |
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4 Barrel venting
| The screw
channels of systems employing
counter-rotating, intermeshing screws
are only partially filled with material
in the venting area. This allows
particularly efficient venting of both
conical and cylindrical screws. The
vacuum unit, together with the
separator, is installed in the extruder
frame and is readily accessible, like
all elements requiring service. |
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5 Operation
| The control
and monitoring elements are mounted in a
swivelable housing at the barrel outlet,
near the die. This facilitates optimal
operation with simultaneous product
monitoring. |
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6 Barrel
Reifenhäuser barrels are mainly made of
nitriding steels.
Barrel zones exposed to extreme wear can
be equipped with hard alloy bushes
(PM-HIP technology). Linings of this
type reduce corrosion and wear problems
to a minimum and enhance the barrel
service life.
The compatibility of the screw and
barrel and their design have a decisive
influence on the quality of the final
product.
PM-HIP technology
Reifenhäuser uses PM-HIP technology to
manufacture armouring layers. This
technology combines powder metallurgy
(PM) with hot isostatic pressing (HIP).
Special powder-metallurgy alloys are
compressed in closed containers at high
temperature and pressure. The generated
layers have a very fine, homogenous
structure that is free of cracks and
pores.
Later, during operation, this structural
matrix largely withstands wear caused by
abrasive materials used for filling and
reinforcing. |
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7 Screws
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