Product category:
Robotics, Handling and Storage
News Release from: Dynaspede Integrated Systems | Subject: Pay-off Stands for Optic Fibres
Edited by the Engineeringtalk Editorial
Team on 09 January 2003
Tensioning system keeps fibres under
control
Dynaspede has developed a novel and cost effective tensioning system for reels of optical fibre that offers direct and precise 4-Q torque control under transient and steady-state operating conditions.
Dynaspede has developed a novel and cost effective tensioning system for reels of optical fibre that offers direct and precise 4-Q torque control as needed under transient and steady-state operating conditions The twin requirements of delicate handling and tight control of filament tension are the basic process demands of any modern-day optic cable line
The unforgiving and fragile nature of optical fibres puts severe demands on an appropriate control system.
Any acceptable control system has to provide a stable, highly responsive and transient-free control of filament tension, especially at the inlet section.
Optical fibres need relatively low and narrow band of allowable tension values and cannot withstand momentary tension spikes resulting from inertial loading of conventional tensioning devices.
Top-of-the line servomotor based control systems (operating in torque or speed modes) have so far been the only acceptable answer to meet these challenging process demands.
However, the cost of installing such tension control systems, individually on each of the multi-unwind stands have prompted engineers, worldwide to search for viable alternatives to servomotor controls.
The development of special high-performance "magnetic particle transmissions" now holds the promise of performance at a fraction of the cost of comparable servo systems.
In this approach, an electronically controlled "magnetic particle transmission" provides bidirectional control of individual unwind stands.
A special, self-compensating low inertia S-roll assembly, in the path of each filament, serves to monitor and regulate the tension.
Such a combination is found to track the filament tension with unerring accuracy from start to finish.
Any tension disturbances arising out of external reasons are largely compensated due to the accumulating nature of the S-roll assembly.
Dynaspede's proprietary magnetic particle form of transmission, attached to each of the unwind stations, serves to let off the filament at preset tension.
In principle, this device is essentially an electronically controlled magnetic particle clutch-brake combination having a synchronous motor as a torque source at its input.
The output shaft of this drive delivers a driving torque as needed during machine acceleration and provides a controlled braking during normal unwinding operation.
A speed sensor at the output of this device, feeds back this information to an external electronic controller, located inside the S-roll assembly.
The magnetic particle device functions as a perfect dual-channel transmission operating under closed loop feedback from a tension tracking and controlling S-roll assembly.
The S-roll assembly is a carefully crafted tension tracking and controlling device capable of absorbing momentary tension transients because of its accumulating nature.
The lightweight, S-roll design is dimensioned from inertia considerations to accurately track and control the filament tension with a good measure of filament accumulation during sudden changes in line speed.
The electronics that constantly control the filament tension are built around a micro-PLC, orchestrated by a dedicated software and application specific cards.
The unit is housed directly beneath the S-roll assembly.
The control scheme operates around two control loops.
A fast acting speed control loop computes and increases the unwind speed in proportion to the turn down and instantaneous value of spool diameter.
The position feedback from the S-roll assembly operates through a subordinate control loop to fine tune the filament tension precisely to the desired value.
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