The Theory Of Fiber Length Damage And Distribution In The Worsted Spinning Process

The wool fiber length is very important to the spinning properties and quality, and it is difficult to comeback when they change (breaking and hooking). Therefore, it is useful to modulate techniques and equipments and instruct practical producing by investigating fiber length distribution and damage in worsted spinning process.Fiber-length will be damaged and shortened in top-making due to fiber breaking, namely the explicit damage. Through a two-time (sample C) aligning the fiber bundle with a uniformity end by Almeter sampling machine (FL-100), the fiber-length parameters can be obtained for the analysis of the length damage. The difference rate and the damage percentage calculated from the length parameters have been proposed to characterize fiber-length explicit damage effectively and accurately. The tested results verify that the explicit damage takes place more in beginning stages, but still keep 2-4% damage percentage in following processing and the more sensitive and stable parameters to evaluate the damages are the differential rate calculated from short fiber percentage (SFP), Hauteur length and Barbe length.Fiber-length will be damaged and shortened in top-making caused by the implicit damage, i.e. fiber bending and hooking. Based on atwo-end sampling-fiber method from a top to align two fiber bundles with a uniformity end by Almeter sampling machine (FL-100), which are called as Sample A & Sample B, the fiber-length parameters can be measured for the characterization of the fiber damage. A series of new parameters, namely difference rate and the damage percentage, have been proposed to characterize fiber length implicit damage effectively and accurately. The tested results indicate that the fiber hooking rate can be reduced but there are 15% remnants of hooking fibers and the more sensitive and stable parameters to evaluate these two damages are the differential rate calculated from short fiber percentage (SFP), Hauteur length and Barbe length.In the carding and spinning, fiber real length and project length are changed or damaged. The former is caused by fiber breakage, and the latter is due to the hooked fibers. The accurate express of the two length in the carding and spinning is vital important to reduce fiber length damage, to enhance fiber combing effect, and to increase yarn quality. To the analysis of the two length damages, sample A, B and C are the basic testing specimen. However the present fiber-length parameters are poor on the characterization of the two sorts of length damages in precision, sensitivity and pertinency. Therefore the calculation of the differentiation between fiber length distributions should be adopted. The theoretical analysis and experimental results indicate that the explicit damage (fiber break) and the implicit damage (hooked fibers) occurring in each processing step can be formed by the differentiated areas of fiber length distributions. So that it can be a criterion for processing improvement and optimization in spite of simple. Therefore, it is essential for the explicit damage to obviate the excessive strike, combing and drafting;and for the implicit damage, it is also essential to adjust the speed of carding and combing, and to modify the fiber surface.The fiber length parameters have high linear correlation, and can be displaced each other. Such as the Hauteur parameters calculation based on fiber-number: H-H%<30mm, H%<30mm-CVH-CL;At the same time, the Hauteur parameters calculation based on fiber-number and the Barbe parameters calculation based on fiber weight also have high linear correlation, especially between H-B%<30mm, H%<30mm-B%<30mm, L5%-B. But, the explicit and implicit damage percentage which calculated based on fiber length distribution has poor correlation with some monomial and synthetic index calculation based on fiber length parameters. To some extent, these implicate that damage percentage calculation based on fiber length distribution don't affected by some length parameter, but all of them and their synthetic index.Fiber length distribution character will be worse caused by fiber length damage in the worsted spinning process, and it also will attribute poor effect to yarn quality in the next process. For instance, the coefficient of variation CVH and CVB of the fiber length become big along with the process. It also implicate that the fiber length distribution character will be worse and the breakage will be increased in the spinning and weaving. So we shall monitor the process at each step, to reduce fiber length damage and to improve the yarn-quality in the worsted spinning process.