EoW September 2009

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EuroWire – September 2009 34
technology news
Maschinenfabrik Niehoff has developed
the DSI series of double twist stranding
machines, and additional equipment
which can be combined tomanufacture all
types of data and special cables, including
LAN cables of all existing categories and
even future generations.
An example application of the versatility
of Niehoff’s double twist stranding lines
is the manufacturing of instrumentation
cable for the petrochemical industry. In
this case, the cable consists of two flexible
conductors with polyethylene insulation,
two fillers and a drain wire (ground).
During the stranding process, the inner
part of the cable has to be wrapped with
three film layers. All elements of the
cable are assembled in one process on a
stranding line which is composed of three
payoffs type ATP 630, three payoffs type
ALB 600, a pre-twister type VVD 180, and
a DSI 631 type double twist stranding
machine.
ATP 630 tangential payoffs are designed
for the uncoiling of cables, insulated
single conductors, pairs and quads with a
maximum diameter of 4mm. Each payoff
is driven by a dancer-controlled spool
drive with adjustable wire tension; the
maximum haul-off speed is 300m/min.
In this case, the units were used to payoff
the two flexible insulated wires and the
ground wire.
The ALB 600 longitudinal tape payoffs
with tape forming are driven by a
dancer-controlled AC motor; they are
designed to enable an easy and rapid film
insertion and tensioning. The film tension
can be adjusted separately and the
forming tools for overlapping either on
the right or left can be quickly exchanged.
The payoffs can be operated with payoff
spools or film disks and are suitable for
films with a maximum width of 40mm
and a maximum thickness of 65µm. The
maximumhaul-off speed is 300m/min.
The pre-twister VVD180 has been
developed for the cost-effective produc-
tion of insulated wires, pairs, quads
and cable cores with 5- or 7-conductor
design and three or more films applied
in the S or Z twist direction by double
twist stranding machines. The pre-twist
devices enable the application of tapes
under a reduced, controlled and constant
tension. The devices can accommodate
tapes made from all kinds of films used
for data and special cables. The speed
can be infinitely controlled. The VVD
pre-twisters are designed to handle
stranded products with a maximum
diameter of 10mmor 15mm.
Double twist stranding machine DSI 631
is used for a wide conductor cross-section
range and a maximum strand diameter
of 8mm. The lay length can be freely
adjusted from 8mm to 180mm with a lay
length tolerance of less than ±0.5% of
the effective lay length. The DSI 631 and
the larger version DSI 1001 are designed
to cable insulated conductors into pairs
or quads and to strand conductor pairs
into LAN cables and other special cables,
with or without back twist. Depending on
the respectivemachine version up to three
films can be applied.
An important feature of the DSI stranders
is the single bow design that results in a
significantly reduced energy consumption
and noise emission. Three-phase drive
technology and non-contact machine
data transfer reduce maintenance to a
minimum. All production parameters are
set using the machine’s HMI touch screen
display where they are clearly visible,
together with service and maintenance
messages.
Maschinenfabrik NiehoffGmbH& Co
KG – Germany
Fax: +49 9122 977 155
Email:
Website:
Double twist stranding of
instrumentation cables
DSI 631 type double twist stranding machine ▲ ▲