This machine is intended to clean and parallelise the fibres and to produce a card sliver in which fibres are regularly distributed (Fig. 4).
The card carries out also a cleaning action. The careful study of the clothings and of the air passages permitted to increase further the productivity of these machines.
An industrial production of 50-60 kg/h has become to-day a quite usual reference. This result has been attained by further developing following features:
· the feeding of a batting of constant count, well opened and sufficiently cleaned
· a more intensive opening and cleaning action, by the licker-in, with an effective waste removal
· the improvement of the suction system
· the automatic control of the sliver regularity and quality, in terms of neps.
The cotton drawing frames
The purpose of this machine is to parallelise the fibres by doubling and drawing several slivers.
In order to produce a sliver with maximum regularity, automatic adjustment systems are used for reducing short-, medium- and long-term variations in the sliver weight. In fact sensors are used to measure the variations in sliver weight, and the consequent necessary corrections are applied by varying the draft, that is the speed of the delivery rollers as compared to the feed rollers.
Depending on the envisaged end-product, one or two drawing frame passages can be made. This processing stage is extremely important for the regularity of the end-product, as the following machines (the roving frame and the spinning frame, both ring and rotor frame) cannot correct any more the weight irregularities of the roving and of the yarn.
