1. In direct counting method, one end of the sample is fixed, and the other end turns to the untwisting direction until the fibers in the yarn are completely straight and parallel. The untwisted twist is the twist of the sample length. Direct counting method is the most basic method to measure yarn twist, and the measurement results are more accurate, which is often used as the standard to check the accuracy of other methods.
However, the efficiency of this method is low. If the fibers in the yarn are kinked, the fibers are not easy to decompose and parallel, and the yarn is easy to break due to the decomposition of fibers. The direct counting method is generally used to count the twist number of roving or strand, while the black-and-white yarn counting method can be used to test the spinning, that is, a black roving and a white roving are fed into the same spindle to spin out the black-and-white yarn, and the sample is clamped on the twister, which is the same as the direct counting method for untwisting. With the increase of untwisting, the distance between black and white yarn becomes larger, and the easier it is to count manually. Generally, when the untwisting reaches about half of the total number of twists, the remaining number of twists can be counted manually. The total number of twists on the yarn is the sum of the untwisting number of the twister and the remaining number of twists counted manually.
2. Untwisting and twisting method
The untwisting and twisting method is based on the assumption that under a certain tension, the yarn elongation after untwisting is the same as the yarn shortening during reverse twisting.
