EuroWire Sept 2015

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Technology
September 2015 42
Magnetic particle clutches and brakes are suitable for tension
and torque control. Clutches are used for rewind tensioning, and
torque limiting. Brakes are used for unwind tensioning.
Performance, accuracy and life are greater than friction clutches
and brakes, since magnetic particle units have no friction plates
to wear or give off dust.
Slip torque is smooth and infinitely adjustable. Torque is varied
from near zero to maximum by varying input current.
Units from 1oz inches to 300lb-feet, with heat dissipation up to
1,900 watts continuous duty are available from stock.
The DC constant-current power supplies power the clutches,
with output current controlled manually with a potentiometer,
or by a 0-10 volt signal voltage from a computer or PLC.
The Placid Industries follower potentiometer or ultrasonic
sensor connects directly to the power supply to make a constant
tension unwind system. As the roll diameter decreases, the
current energising the brake is decreased to keep tension
constant.
Placid’s hysteresis brake produces torque without physical
contact, ensuring torque is very precise and repeatable, and
providing a very long life.
Applications include torque and tension control for web
handling (unwinding), and load simulation for testing motors
and drives.
Torque can be varied from three per cent to 100 per cent by
varying input current. This also provides a very wide RPM range
while the cog-buster automatically decogs (eliminates torque
ripple) with one revolution.
Placid Industries Inc – USA
Website:
Ideal for tension and torque control
▲ ▲ Tension and torque control from Placid Industries