Rieter

Trash removal

Index

Basically, all trash removal devices in rotor spinning machines are the same, i.e. no more than a larger or smaller opening in the opening roller housing. The high peripheral speed of the  opening roller results in all particles heavier than fibers (trash and other extraneous particles) being removed outward at this opening while the fibers continue with the roller, to be passed later into the fiber channel. The expelled waste falls onto a conveyor belt, which carries it alternately to the headstock or the tailstock. At both sides of the machine the collected waste is removed by suction nozzles and fed by vacuum to a central filter housing. Wipers on the conveyor belt continuously clean the housing under the opening roller.

As explained in detail in section  Preparation of raw material, modern spinning preparation machines with the appropriate cleaning facilities are able to remove most extraneous, dust and trash particles reliably from the raw cotton. However, a certain amount of organic and inorganic extraneous matter can survive the cleaning process in the blowroom and drawframe, depending on the susceptibility to cleaning of the cotton(s) being used and due to the picking and ginning methods.

Efficient trash removal is therefore one of the most important preconditions in the rotor spinning system for stable spinning conditions and high yarn quality. Unfortunately, the collecting groove of the spinning rotor not only collects fibers; particles, trash, dust, etc., also accumulate in it, changing the groove‘s geometry and thus the yarn quality, and in the worst case causing a deterioration in spinning stability. Due to the extremely high centrifugal forces, a tiny trash particle of only 0.2 mg can exert a force of approx. 15 g on the fiber ring and thus prevent twist propagation, which results in a thread break. This clearly illustrates the importance of effective trash removal for the operation of the rotor spinning machine.

Trash removal in the spinning box ensures that the overwhelming majority of extraneous matter still in the fiber sliver and disturbing the spinning process is eliminated. However, trash removal in the spinning box can by no means replace careful cleaning of the cotton during spinning preparation. The lower the residual trash content in the drawn or carded sliver fed in, the more effectively can the remaining trash and extraneous particles be reduced in the spinning box.

Trash removal systems with an adjustable BYpass (Fig. 11, Fig. 12, Fig. 13), which enables the cleaning effect to be adjusted individually to the raw material being used, i.e. its trash content, are especially effective. On conventional spinning boxes almost all the air necessary for the vacuum is sucked in through the trash removal opening, i.e. in the opposite direction to the expelled trash. In some cases secure trash removal might be impeded, mainly in the case of small and/or light impurities.

The bypass permits adjustment of the air flowing into the trash removal opening depending on the raw material. The larger the amount of air provided through the bypass, the smaller the quantity of air drawn in at the trash removal opening, and the easier it is to separate impurities. Furthermore, it prevents any trash particle already disposed of from being sucked back into the spinning box again.

Fig. 11 – BYpass open (maximum trash removal)

Fig. 12 – BYpass half open (medium trash removal)

Fig. 13 – BYpass closed (minimum trash removal)