Mechanical combing in manual
Three components were used in manual combing: the hand and two combs. The hand acts as a gripping means while the combs process the head and the tail of the tuft.
Mechanical combing is carried using linear combing machines which reproduce the actions of hand combing; the comb is still the combing means while the hand of the “combing roller” is replaced by different gripping means.
Linear combing machines work first the head and then the tail of the fibre tufts and include:
* a nipper, retaining the tuft,
* a circular comb, acting on the tuft head,
* a linear comb, acting on the tuft tail,
* a nipper, extracting the tuft from the machine
Figure 1 shows the four different positions assumed by the components of a linear wool combing machine.
In a few words, a linear combing machine operates as follows:
A lap of fibres, formed by 20-24 slivers partly arranged one beside the other and partly overlapped, is fed by the feeding cylinders (not shown in the pictures). The fibres are laid between the “a1″ grooved plate and the “a2″ separating apron, which, together with the “a3″ needle bar make up the “A” feeding gill.
While “P” rotates, the combs of the “p1″ sector – whose needles which are thinner in the first rows (sorting area) and thicker in the last ones (finishing area) are inclined in the direction of the material flow – clean and comb the tuft (head) while the “A” gill carries out a return stroke of adjustable “V” width. During this motion, which prepares the feeding of the following tuft, the lap of fibres slides between “a1″ and “a2″ and stops since it is retained by the “T” closed nipper (Figure 1, top right).
When the “A” gill moves towards the open nipper, the fibre lap follows its motion and the following tuft is presented to the comb; the “a3″ needle bar lowers and its needles penetrate the “a1″ and “a2″ spaces separating the short fibres.
After the last “p1″ needle row has combed the head of the tuft, the “S” extraction cylinders (including the “s2″ grooved cylinder and the “s3″ sleeve sliding on the s1 grooved cylinder) which have approached the circular comb, catch the head of the tuft and the “R” linear comb lowers and penetrates it with its needles. At this moment, the “T” nipper opens, the “A” gill moves forward and the tuft tail, pulled by the extraction cylinders (which rotate and oscillate thus drawing back from “P”) is separated from the lap and combed by the needles of the “R” linear comb (Figure 1, below left).
The “s1″ and “s2″ cylinders are powerfully pressed one against the other to grant a perfect nipping of the tuft; furthermore, during the approaching oscillation of the circular comb, they rotate in the direction opposite to the material flow direction to draw back the previously combed tuft; this motion is necessary to overlap the tuft to the already combed one and ensure a good evenness of the combed sliver.
Once the tails of the tuft have been combed, the “T” nipper closes in order to retain the newly fed tuft, the “A” gill, which has moved completely forward, returns along the “V” section with the “a3″ needle table raised, the “R” linear comb raises, the “S” extraction cylinders prepare to rotate (to draw back the material) and move (to approach “P”) and the circular comb, which has almost completed one revolution, approaches the tuft protruding from “T” with its first needle row (Figure 1, below right).
The tufts of combed fibres arranged on the “s3″ sleeve, with the head overlapping the tail of the preceding tuft, form a thin web which, condensed into a sliver, is finally conveyed to a collection can.
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