Pay-off Stand for Optic Fibre

A unique & cost effective tensioning system that lets off all your tension …..

• An innovative, technological breakthrough
• Offers direct and precise 4-Q torque control as needed under transient and steady state operating conditions
• Most cost -effective than a servo-drive system

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 optic fibres makes severe demands on a 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.

Optic 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 answer to meet these process demands. However, the cost involved in installing such systems individually on each of the multi-unwind stands have prompted engineers worldwide to look for viable alternatives to servomotor controls.

The development of special high performance “Magnetic Particle Transmissions” 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 bi-directional control of individual unwind stands. A special, self-compensating low inertia S-roll assembly in the path of each filament monitors and regulates the tension. Such a combination accurately tracks the filament tension 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.

Components

Magnetic Particle Transmission

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 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.

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 light-weight, 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 Control unit

The electronics that constantly controls the filament tension is built around a micro-PLC, orchestrated by 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 turndown 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.