Rieter

Roving stop motion

Index

Fig. 30 – Roving stop motion by Luwa

Monitoring at the delivery of the drafting arrangement can also be performed by light barriers. In this case, the light beam is usually directed straight past the flyer tops. In the event of a roving break, the broken roving end whirls around the flyer top or so-called „hoods“ form at the flyer top. This interrupts the light beam and causes the machine to be stopped.

An alternative is the use of the capacitive detection principle in a monitoring unit. The Luwa company offers such a device under the designation „Pneumastop“. The device is associated with the pneumatic suction system in the delivery of the drafting arrangement. This suction system (Fig. 30, a) is an absolute necessity in order to avoid a series of roving breaks along a bobbin row following the first break in the row. If one end breaks, the suction system draws the sliver into a large collector duct extending over the full length of the machine. Fibers entering this duct pass through it into a filter chamber at the end of the machine after passing the capacitive detector (Fig. 30, b). In the detector there is an electric field between two comb electrodes. If fiber material passes through this field, the change in capacitance generates a signal to stop the machine. Modern machines are mostly equipped with individual electronic roving detectors placed at the outlet of the drafting unit. These electro-optical detectors ensure that in the case of a roving break the machine is stopped immediately.