WCN Spring 2011

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WCN Issue N° 44 27
This picture clearly shows what a
laying pattern should not look like. On
the left you can see a hill, on the right
there is a valley.
The Niehoff solution:
Automatic traverse width control in
the spoolers
The most time-consuming activity of
the operator besides wire feeding is to
control and to adjust the correct wire
laying.
It is absolutely necessary for a safe
and smooth paying-off of the wires in
the downstream process step to watch
the wire lay very closely.
Niehoff has developed and patented
an automatic system which controls
and corrects the traverse using a
special software program.
The constant speed control at
the traversing unit recognises the
formation of hills or valleys due to the
aligned change in wire speed.
A higher speed indicates the formation
of a hill – lower speeds mean the
formation of valleys. Special software
detects and processes these points,
and corrects them in the next traverse
movements.
The consequences of a poorly wound
spool appear in the downstream
process and are the main reason for
wire breaks and slow speeds there.
Niehoff has also developed an
automatic traverse control for bunching
machines based on the optical control
of the flanges.
In the stranding process, wires are
often spooled on plastic spools with
high winding tension. Here it is very
important to determine the exact
switchover point to avoid the flanges
to flare out.
Two laser sensors control the flange
position, and the traverse unit which
is driven by a stepping motor moves
towards this position.
This ‘Niehoff Bunching Automatic
Traverse’ system (NBAT) was
introduced to the market a few years
ago and many cable makers have
realised its benefits.
Spools wound with the help of
this system enable a trouble-free
paying-off before the extrusion lines at
line speeds of up to 1,500m/min.
The constant winding tension
throughout the spool filling is another
important point in wire stranding.
Niehoff has equipped its bunching
machines with load cells and dancer
pulleys to control, using a closed loop
control system, the set winding tension
throughout the spool filling.
Conclusion
As far as the basic machines are
concerned, the processes for the
production of strands do not differ
considerably. If you want to be better
than the standard and produce
high-quality strands, the mentioned
details help you and result in quality
improvements of the finished products
and high production safety with fewer
mistakes as well as higher customer
acceptance.
Back to the loss of elongation
A first-class annealer should produce
wire elongation values much above
DIN standard. The target should be
to maintain them as far as possible
through the whole process up to the
final cable product by following all
recommendations mentioned before.
For the sale of cable its conductance
is more often the determining/decisive
factor than its cross section. This
means the less the loss of elongation
produced in the production line, the
lower is the resistance and the higher
the electric conductance of the cable.
This means that a bad conductance
requires more copper in the cable;
good conductance on the contrary
needs less copper.
Automatic traverse control
Valley
This does not look good and
could be better
Automatic traverse
control for spooler
- Detection of flange and change-over
- Spooling without hills and valleys
- Target: pay-off speed up to 1,500rpm - Traverse drive with stepper motor
- Electronic device NBAT2
- 2 laser sensors at the traverse pulley
D631 with automatic traverse system