Rieter

Operating sequence

Index

Fig. 2 – Cross-section through a roving frame

Drawframe sliver is presented to the roving frame in large cans (Fig. 2, 1). The can diameter does not correspond to the spindle gauge, so the cans are not arranged in one row but in several, which have to be set out behind the machine. Driven transport rollers (2) are provided above the cans. These draw the slivers from the cans and forward them to  drafting arrangement (3). The drafting arrangement attenuates the slivers with a draft of between 5 and 20. The strand delivered is too thin to hold itself together and a strengthimparting step is necessary immediately at the exit of the drafting arrangement. This is performed by inserting protective twist, usually in the range of 25 - 70 turns per meter. The turns are created by rotating  flyer (6) and are transmitted into the unsupported length of roving (5) between the flyer and the delivery from the drafting arrangement. The flyer itself forms part of driven spindle (7) and is rotated with the spindle.

To ensure that the roving is passed safely and without damage to the wind-up point, it runs through the flyer top and the hollow flyer leg, and is wound 2 - 3 times around the  presser arm before reaching bobbin (8). To enable  winding to be performed, the bobbin is driven at a higher peripheral speed than the flyer so that the roving is drawn off the flyer leg. The coils must be arranged very closely and parallel to one another so that as much material as possible is taken up in the package. For this purpose, bobbin rail (9) with the packages on it must move up and down continuously. This can be effected, for example, by continual raising and lowering of lever (10), on which the bobbin rail is mounted. Since the diameter of the packages increases with each layer wound, with a corresponding increase in the length of roving wound per coil, the speed of movement of the bobbin rail must be reduced by a small amount after each completed layer. Similarly, owing to the increase in package diameter, the bobbin‘s rotation speed must be reduced after each layer, because delivery is constant and hence the difference between the peripheral speeds of the package and the flyer must also be kept constant throughout the winding operation. Only in this way can a controlled winding operation be achieved.