17—21. DOUBLED YARNS. PARTS I TO V

This series of papers deals mainly with the effect of singles twist, doubling twist and doubling tension on the following physical properties of the folded yarn: strength, extension, snarling tendency, take-up and doubling twist. Part I deals specifically with two-fold yarns, twisted S on Z, spun from a mediumstaple American cotton, a carded Sakel cotton and from viscose rayon staple (Fibro). Particular emphasis is laid on the effect of singles and doubling twist on the above physical properties of the doubled yarn; doubling tension is, however, shown to be important and the need for further work on the effect of doubling tension is indicated. Part II deals solely with the effect of doubling tension on one type of folded yam—on 80s/2 combed Sakel, spun with a twist factor of 3·2Z and doubled with a twist factor of 5·5S. Both ring- and mule-spun singles were used. The doubling tension was varied by changing the traveller weight, spindle speed and ring diameter, and tests are described showing the effect of...