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While winding
up the film on one station, on the
other side of the unit the
completed jumbo roll can be removed and an empty winding core can be fixed.
When starting-up the line, the film is wound on one winding station, first. Then,
the machine parameters are optimized, and finally, the film can be laid on to the empty
winding-core by the automatic lay-on and cutting unit.
It is necessary to adjust the winding characteristics to obtain well-wound film
rolls.
The computer system pre-sets the winding characteristics via Force/Diameter
diagram, displayed on the screen.
1.7.1 Tension roll
The function of this roll, mounted on both sides on the high precision electronic
load cell, is to permanently monitor the film tension just ahead of the contact roll and
to wind the film at a constant tension.
Winding with tension control is possible in gap or contact modes.
The software calculates of the AC motor torque
according to the tension
setpoint and the mill roll diameter.
The load cell (located on the tension roll) measures the film tension and corrects
the torque of the motor to have a tension equivalent to the set point.
The tension is set on the CPCS winder tension view according to the mill roll
diameter. The winding is done in torque regulation with speed control to avoid having
over-speed in case of film break.
1.7.2 Contact roll
The
function of this roll, is to remove air between
the film layers and to
maintain the layers.
1.7.3 Contact winding
The film is wound with the contact roll pressing the mill roll.
A pneumatic regulator controls the pressure applied to the mill roll to ensure a
constant contact pressure (the contact pressure is defined in the CPCS winder pressure
view according to the mill roll diameter).
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Every time the carriage reaches the detection switch it starts moving backward
till it pulls away again. The contact mode used for
a thin film with thickness < 36µ.
As the film is thin, there is air between the layers when winding. So, to remove
it, it is necessary to apply more pressure on the roll (air gives bad characteristics to the
film (waves)).
Winding with tension control is possible in gap or contact modes.
The software calculates of the AC motor torque according to the tension
setpoint and the mill roll diameter.
The load cell (located on the tension roll) measures the film tension and corrects
the torque of the motor to have a torque equivalent to the set point.
The tension is set on the CPCS (Computerized Process Control System) winder
tension view according to the mill roll diameter.
The winding is done in torque regulation with speed control to avoid having
over-speed in case of film break.
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