Described is a new method of yarn-twist measurement based on observation of the behaviour of yarns during measurement of their twist. The method consists in a two-way twisting, i.e. untwisting and re-twisting, of the test sample pre-loaded at the midpoint of its length. Due to the central loading of the sample the latter is slightly bent in the middle and, therefore, no ballooning occurs when the sample is being untwisted and re-twisted.
The new twist test is referred to as a two-way twisting method. For this method a new tester was developed, which was given the name of Twist-Tester CZ/V-1. This twist-tester has two rotary clamps that revolve at the same speed in opposite directions and a special device that imparts pre-tension to the yarn sample at its middle point. A comparative analysis of the results obtained by the two-way twisting method and results obtained by the reverse twisting method which uses the Zweigle twist-meter showed that the proposed new method was more accurate and 50% less sensitive to the value of pre-tension of the sample. In the new method the sample does not balloon while it is being untwisted and re-twisted and, therefore, the sample is not subject to uncontrolled elongation due to inter-slippage of the fibres.
The two-way twisting method and the twist-meter CZ/V-1 successfully passed the test on ring-spun and open-end yarns. The results confirmed its superiority over the existing twist-testing methods.
The new method and the device CZ/V-1 have been filed for protection at the PL Patent Office, ref. P-344096.
The work was carried out under Research Project No 8 T10C 008 13 financed by KBN (Committee for Scientific Research).
By: Zdzisvaw Czaplicki Institute of Natural Fibres, Poznań, Poland
Submit Date: 12/31/1999 20:00