exceeded the actual spinning machine in extent and complexity.
To-day there are three distinct methods of producing worsted yarn.
Firstly, there is the preparing and spinning of the true worsted
thread, this being made from long English and colonial wool. In
this class should also be included mohair and
alpaca. Secondly, there is the preparing and
spinning of what are known as cross-bred and
botany yarns, these being made from cross-bred
and botany wools. Thirdly, there is the preparing
and spinning of short botany wools on the French
system. There is a fourth class of worsted yarns,
principally carpet and knitting yarns, which are
treated in a much readier manner than any of the
foregoing, but as the treatment is analogous—with
the elimination of certain processes—to the second
of the foregoing, it is not necessary to refer specially
to it.
Fig. 11.—Sectional View of Back-washer.
A are the delivering rollers, B, B are the immersing rollers in the first tank, C, C are the press rollers to squeeze out superfluous liquors, D is the immersing roller in the second tank, and C′, C′ are the press rollers for the second tank. Drying cylinders E to E″″ may be arranged as “live-heat” cylinders, as secondary heated cylinders or as air drying cylinders. The roller F directs the slivers into the back rollers G of the gill-box, which in turn delivers up the slivers to the fallers H, which in turn delivers the wool to the front rollers I.
To obtain a sliver or “roving” which can be satisfactorily spun into a typical worsted thread the following operations are necessary:— preparing (five or six operations), back-washing, straightening, combing, straightening and drawing (say six operations), and finally spinning on the flyer frame.
After long wool has been scoured and dried it is necessarily considerably entangled, and if it were to Preparing. be combed straight away a large proportion of the long fibres would be broken and combed out as “noil” or short fibre. To obviate this the wool is fed as straight as possible into a sheeter gill-box; after this it passes through other two sheeter gill-boxes, then through say three can gill-boxes. As shown in fig 10 the main features of a preparing or gill-box are the following: the feed sheet upon which the wool is “made up,” the back rollers B which take hold of the wool and deliver it to the fallers F which, working away from the back rollers more quickly than the wool is delivered, comb it out. The fallers in turn deliver the wool to the front rollers D, which, taking in the wool more quickly than the fallers delivering it, again draft and comb it, but with a reversing of the former combing operation. The wool emerges from the front rollers as thin attenuated continuous fibre about 12 in. wide, which is wound upon an endless leather sheet H from which the box takes its name. When a sliver of sufficient thickness has been wound upon the sheet, it is broken across and fed up at the next gill-box. The fourth gill-box delivers into cans instead of on to a sheet. A number of cans are then placed behind the fifth box and the slivers from these fed up into the back rollers, and similarly with the sixth. The primary object of “preparing” or gilling is to straighten and parallelize the fibres in the sliver This is effected by means of the combining or doubling and drafting to which the slivers are subjected. In addition to this, however, a level sliver suitable for combing is formed by the combined action of the drafting and doubling which has taken place at each box.
Fig. 12.—Plan and Section of the Noble Comb.
A, A is the large comb circle and B, B′ the two small comb circles. The slivers are delivered by the mechanism C to the feed boxes D, being thrown across the pins of the large and small circles at position E. A stroke at F suitably directs the fringes of fibre as the circles separate and the combed fibres are taken hold of by drawing-off rollers G and G′ and combined to form the “top.” The brushes H, H and the noil knives I clear the small circles of the “noil.” The feed knife J in conjunction with the inclined planes at K are instrumental in feeding a previously directed length of sliver over the two circles as they practically touch one another at the point E, and so the process is continued.
Oil will have been added to the wool at the first fibre as the circles preparing-box to cause the fibres to work well, Back-washing. Were this all, there would perhaps not necessity for back-washing. But the silvers during their passage through the preparing-boxes become sullied naturally, and in addition, owing to the opening out of the locks of wool, dirt which was not “got at” in the scouring now works out and further sullies the slivers. It is consequently necessary to scour the slivers again, this being effected in what is termed a back-washing machine. This machine as shown in fig. 11 usually consists of two scouring tanks with immersing rollers, drying cylinders, a gill-box and oiling motion. The slivers on emerging from this machine should be clean, fairly straight and in good condition for combing. Their condition may be further improved by passing them through
