Doffing
Although it takes between 2 and 4 hours to fill a cop depending upon yarn fineness, process limitations restrict weight of the yarn on the cop to the range 50 – 140 g. Therefore adding an additional processing stage is unavoidable after spinning. In case of hand doffing, this thread reverse is formed on the tube, and in the case of automatic doffing on the spindle.
The reverse is needed so when the cop is doffed the yarn is still held on the spindle. Otherwise, a tread break would occur. In modern machines doffing is carried out automatically.
Manuel doffing:
Manuel doffing is un attractive work. It comprises only very few manipulations which have to be performed very quickly and must be continually repeated. Furthermore, the work usually has to be carried out in the bent posture.
![clip_image096[3]](http://compactspinning.in/wp-content/uploads/2010/03/clip_image0963.gif "clip_image096[3]")
![clip_image098[3]](http://compactspinning.in/wp-content/uploads/2010/03/clip_image0983.gif "clip_image098[3]")
A doffing beam also extending over the full length of the machine side and fitted with nipples insertable into the tubes.
A lifting mechanism, usually in the form of a scissors mechanism, for raising and lowering the beam and also for swinging it in and out. A tube preparing and donning device at one end of the machine. A cop receiving unit at the same end of the machine.
During the whole of the cop winding operation the doffer stays in its rest position. When the cops have been filled the lifting rods swinging out the beam while simultaneously raising it. When the uppermost position of the beam has been reached, the rods swing the beam in so that the beam moves over the cops and is then lowered until the nipples engage within the cop support tubes. Once the cops have been grasped the beam is raised, thus lifting the cops off the spindles. The rods swing out, lower the beam and move it over the conveyor. The cops are then seated on the belt.
Thereafter the pressure air is vented and the cops are released.
Although it takes between 2 and 4 hours to fill a cop depending upon yarn fineness, process limitations restrict weight of the yarn on the cop to the range 50 – 140 g. Therefore adding an additional processing stage is unavoidable after spinning. In case of hand doffing, this thread reverse is formed on the tube, and in the case of automatic doffing on the spindle.
The reverse is needed so when the cop is doffed the yarn is still held on the spindle. Otherwise, a tread break would occur. In modern machines doffing is carried out automatically.
Manuel doffing:
Manuel doffing is un attractive work. It comprises only very few manipulations which have to be performed very quickly and must be continually repeated. Furthermore, the work usually has to be carried out in the bent posture.
Automatically doffing:
A distinction is drawn between two groups of so called auto doffers; Stationary equipment that forms an integral part of the ring spinning machine itself. Travelling carriages that can serve several machines. In most cases a stationary installation comprises essentially the following parts; A conveyor belt that runs past all spindles on one machine side and carries pegs to receive empty tubes and full cops.A doffing beam also extending over the full length of the machine side and fitted with nipples insertable into the tubes.
A lifting mechanism, usually in the form of a scissors mechanism, for raising and lowering the beam and also for swinging it in and out. A tube preparing and donning device at one end of the machine. A cop receiving unit at the same end of the machine.
During the whole of the cop winding operation the doffer stays in its rest position. When the cops have been filled the lifting rods swinging out the beam while simultaneously raising it. When the uppermost position of the beam has been reached, the rods swing the beam in so that the beam moves over the cops and is then lowered until the nipples engage within the cop support tubes. Once the cops have been grasped the beam is raised, thus lifting the cops off the spindles. The rods swing out, lower the beam and move it over the conveyor. The cops are then seated on the belt.
Thereafter the pressure air is vented and the cops are released.