Australian Wool Textile Research (continued)

A major product advantage is that Sirospun allows the economic production of very fine wool weaving yarns, much finer than commercially produced twofolded yarns, and wool is now being more readily considered for fine fabrics that are suitable for the warmer 'trans-seasonal' seasons, e.g. Spring, Winter-Spring, Autumn, Summer-Autumn, depending on the geographical locations.

The adoption of Sirospun technology -over 120,000 spindles (1986) capable of producing 24 million kg per annum of yarn have been converted to the system -encouraged the IWS and the AWC to introduce promotional programs, e.g. 'Cool Wool' and 'Trans-seasonal Wool', to extend the market for wool.

General AWC and IWS promotion programs for Woolmark lay important emphasis on the high-quality nature of wool products, and wool depends greatly on this high-quality image for the maintenance of its price premium over other fibres. Yet achievement of high quality, of course, adds greatly to processing costs. For wool, many of these quality-generated costs arise after spinning. The yarns are normally passed through a device on a winding machine which detects faults, automatically removes the fault, and then ties the two ends of yarns together in some form of knot. Although an improvement on other faults, this knot, of course, is in itself a fault and has to be removed from the fabric or garment by hand, an operation which was estimated to cost the wool worsted industry A$100 million per annum at the beginning of the 1980s.

In the late 1970s efforts were made world-wide to develop robotic-type devices that, instead of knotting the yarns together, re-constituted the yarn in some way, or spliced the two ends together. The main approach used was pneumatic. The two ends of yarn were overlapped and held in a suitably shaped chamber. A turbulent blast of air was then used to intermesh and entangle the fibres. The early pneumatic splices did, however, have some bulk and untidyness, and they tended to be weaker than the parent yarn.

It will be appreciated that with thousands of metres of yarns on each weaving machine, and many thousands of weaving machines world-wide, the costs of splice failure could be very high in machine stoppages. Further, although splices are an improvement generally on knots, in some cases their bulk is high and they have tails -all of which might require manual correction depending on the quality level required.

In 1981, CSIRO[53] developed an alternative approach to splicing using a mechanical mechanism. In this splicer (Fig. 25), the yarn ends are first automatically untwisted, then beards are formed by pulling the two yarn ends away, and the beards are overlapped and twisted together again. The splicer therefore reconstitutes the original yarn structure, and the splices are virtually indistinguishable from the parent yarn, in both strength and appearance.

25 The CSIRO/Savio Twinsplicer. The yarns to be spliced are positioned between annular rubber twisting surfaces that are mounted on metal discs geared to contrrotate (a). The discs are first rotated to reverse the twists in the lengths of yarn between the discs, and the middle sections of yarn are brought together (b). The tails are drafted away (c) following a twist-cancellation step along the tail sections. The resulting tapered ends are lined up with the opposing yarns (d) and the discs rotated in the opposite sense to produce the twofolded central section and adjoining sections of the splice (e).

Australian Academy of Technological Sciences and Engineering