Yarn Manufacturing Machinery - III PDF

Take-off of Material  Take-off of Material Piecing: Detaching roller moves backward and nipper moves forward. After piecing , detaching roller moves forward for detaching the web The coherent web at the detaching rollers is thus lengthened by a new web strip – like roofin...

Take-off of Material  Take-off of Material Piecing: Detaching roller moves backward and nipper moves forward. After piecing , detaching roller moves forward for detaching the web The coherent web at the detaching rollers is thus lengthened by a new web strip – like roofing tiles. Delivered sliver contains periodic irregularities Combed web structure (section view): PD – Piecing distance or piecing period, FL – Fiber length, AL – Detaching length, FP – Fiber package length> AL + FL  Take-off of Material The sliver produced in this way has a wave-like structure with periodic variations In spectrogram peaks are at about 30 - 75 cm This irregularity should be as low as possible  Take-off of Material Hence eccentric withdrawal of the web from the web plate Hence machine settings are based on flat parallelograms Parallelograms are laid on each other in such a way that any unevenness is partly canceled out Incorrect setting will cause an increase in unevenness (Thick or Thin fault)  Take-off of Material For Delivery of web ❖forward component (V) is larger than the backward component (R) ❖Effective take-off (T) = V-R is achieved In modern combers backward movement amounts to about 60% of the forward movement  Take-off of Material Withdrawal of the web and formation of a sliver: Web must be collected into a sliver by trumpet (T) and deposited on sliver table (B) by the calender rollers (K) Web plate (V) for reserve material between detaching (R) and withdrawing rollers (Z) Collection of the web - at the web plate The web can be collected toward the center line (a) - in older web pans, or to one side (b) as on the web plate in modern combers  Take-off of Material With a central collecting action, the slightly thicker piecing lines are formed into curves (piecing waves) If the web is collected to one side (b), the piecing lines form diagonals Collection of web is performed by the sliver trumpet (T) Trumpet (T) size is based on sliver hank Calender rollers (K) serve to condense the sliver  Take-off of Material Sliver take-off: Slivers deflected through 90° by the deflecting pin (P) and are fed together over table (B) to the drafting arrangement (S) Deflector pins - adjustable or can be rotated eccentrically Distance between the sliver trumpet and the drafting arrangement can then be adjusted Piecings of the individual slivers can be shifted relative to each other and all eight slivers are drawn in to common drafting system S B P