Rieter

Bobbin drive

Index

During winding of a roving bobbin, the  flyer rotation speed is usually kept constant. The difference between the peripheral speeds of the flyer and the bobbin must also be kept constant. However, the bobbin diameter increases stepwise, after each layer of roving. The bobbin rotation speed must be reduced accordingly to maintain the required difference between the peripheral speeds. This necessitates a relatively complicated drive for the bobbin.

Variation in bobbin speed originates from the cone drums. When the builder motion shifts the cone belt, the rotation speed of the lower cone is changed. This declining rotation speed is transmitted via gearing (Fig. 16, 80/67) to the differential and is there superimposed on the constant speed of the main shaft. Further gearing then transmits the resulting rotation speed to the bobbin drive (Fig. 17, 4/3). On the bobbin rail, bevel gears (4) fixed to the longitudinal shaft drive the bevel gears (3) of the bobbin supports. But a variable drive, e.g. a PIV unit, can be used instead of the cone drums. A further difficulty in relation to the bobbin drive is the fact that the bobbins are carried on a rail that is continually moving up and down. A flexible (relatively movable) connection is needed between the main drive shaft in the gear box and the longitudinal bobbin shaft. Previously, a kneejoint (swinging joint) was used for this purpose (between wheels 80 and 67 in Fig. 16, and see Fig. 18).

However, gear wheels arranged in a knee-joint have the disadvantage that they roll on each other during the up-anddown movements. This causes additional revolutions that are either added to or subtracted from the basic package rotation, depending upon the direction of the lift stroke. Tension variation then arises. Today, transmission of rotation is mostly effected by means of cardan shafts, telescopic shafts or chain drives.

Fig. 16 – Bobbin drive (gearing plan)

Fig. 17 – Bobbin drive (side view); drive transmission to the bobbin

Fig. 18 – Swinging joint at the bobbin drive shaft