ASSINGNMENT

Electronic let off motion

Submitted By:

Waqar Abdullah(07-NTU-103)

Umair ul hasan (07-ntu-100)

Waqas ahmad (07-ntu-92)

B (weaving)

6th Semester

Submitted to:

Sir Zubair sb

National Textile University

Faisalabad

Electronic Let Off Motion

Definition:Weaver’s beam is driven with the help of servo-motor. As beam diameter changes, rpm of motor are controlled with the help of load cell.

Drive Arrangement:

Servo motors transfer drive to reduction gear box and then to beam by intermediate gear.

Load cell is a very important part in electronic let off motion. It is a pressure sensor. It detects pressure and transfer to AC servo motor. Pressure is transferred through electronic cards , panel and electronic cable.

As diameter decreases , more vibration so more load at cell so give instructions to motor

Newly introduced electronic let off & take up, widely acclaimed as the excellent control & retrofit alternative for air-jet & water-jet weaving machines of various built like Dornier, tsudakoma, Nissan, toyoda, sulzer, himson, etc.

The mechanical let off applies combination of clutches & brakes. The depreciation, function & backlashes of these mechanical parts results in abnormality in density & is unable to fulfill the

needs of quality conscious customers.

Electronic let-off controlThe electronic motor driven let-off supplies the loom with necessary wrap yarn, maintaining the yarn tension constant from full beam to empty beam. Let-off speed is automatically calculated in context with loom speed, weft density, wrap beam diameter & close loop tension control. Accurate synchronization with main motor in forward & reverse direction in addition with remarkable latest features supports to minimize the beginning & ending marks thus, enhancing the grade & quality of the fabric. Besides this, it enables cramming/density design possible.

Electronic take up control for let-offThe let-off & take up is synchronized rigidly with main motor in forward as well as reverse direction. With the take up electronic system the weft density variation doesn’t need any more mechanical interruptions on the loom, it just need setting parameters on the fly of the key.

Control Panel:

We control electronic let off motion by using the control panel we feed a value (warp tension) on panel before running

30-500kgf 0n spun yarn 30-300kgf on filament yarn Warp tension= total ends*f/Ne

For spun yarn

f is constant factor and

f=0.90 for pain weave f=0.6 For top weave(face weave) f=1.1 For back weave

Warp tension= (total ends*denier/100)*0.2-0.45

(0.2-0.45=constant depends on material of filament & weave)