Study On The Condensing Mechanism And Yarn Structure Of Compact Spinning Technology

The compact spinning technology catches lots of career men's and customers' attention for its excellent production quality, so it gets a quick development during the past several years. However, the researching work on the spinning mechanism of compact spinning technology and its yarn structure is very little for its short developing history. This paper will systemically study the spinning mechanism, condensing process and yarn structure of the compact spinning technology after studying and analyzing all kinds of existed compacting machineries.The simulation model of the condensing field is designed on the basis of the Elite system developed by the German Suessen Company and calculated with the standard k-ε model and the finite volume method. In the experimental process, an experimental model is manufactured according to the similar law and measured with the Particle Image Velocity device (PIV). Nine modes are designed and measured, including three negative pressures (-100 Pa 150 Pa and -200 Pa ) and three measuring planes (Z = 10mm , Z = 15mm and Z = 20mm) . The result proves that the experimental data is consistent with the numerical result so that the standard k-ε model can be used to simulate the condensing field in the compact spinning technology completely.After simulation and analysis the air flow velocity in the condensing field of the EliTe? system, it can be concluded that the angle between the air-flow velocity and the delivery direction of the fiber strand at the forepart of the slot is larger than that at the end part of the slot, so that the fiber strand is mainly condensed at the forepart of the slot. The air-flow velocities on the slot edges are calculated so as to analyze the changing trend of the air flow velocity and explain the phenomenon that fiber strands always run along the right edge of the slot. It is also found that the fiber strands begin to be weakly condensed before they reach the slot so that they can be controlled well in this field and can't be accidentally drafted.The effect of the inclining angle of the slot and the negative pressure on theair-flow velocity field is calculated and the conclusion is that the inclining angle of the slot has larger effect on the air-flow field than the negative pressure. Both the changing range of the angle between the air-flow velocity and the delivering direction of the fiber strand and the fluctuation degree of the air-flow velocity on the two edges of the slot increase along with the increasing of the inclining angle of the slot. The air-flow velocity in the condensing field goes up if the negative pressure decreases, but the negative pressure can't give any obvious effect on the distribution of the air-flow field.The occurring condition of tension mechanism of migration is studied and the occurring condition of geometric mechanism of migration is evolved. The fiber migration mechanisms of both the ring spinning technology and the compact spinning technology are studied and concluded that fibers in ring spinning process migrate according to both the tension mechanism and the geometric mechanism of migration, while fibers in compact spinning process mainly migrate according to the tension-dependent mechanism of migration. Therefore, the fiber migration in compact spinning yarns should be weaker than that in ring spinning yarns.The effect of the strand width, the spinning twist and the spinning tension on the shape and size of the spinning triangle and the final yarns' property are studied via experiment. The difference of the spinning triangles between the compact spinning process and the ring spinning process is that the angle and the length of the compact spinning triangle should be smaller and shorter than that of the ring spinning triangle. The force on the fibers in the spinning triangle is analyzed and concluded that the fiber migration in compact spinning yarns should be weaker than that in ring spinning yarns.The spinning triangles of the compact spinning technology and ring spinning technology are calculated in terms of the experiment result. They are used to analyze the occurring mechanism of the hairiness in point of the shape and size of the spinning triangle. The conclusion is gained that the hairiness on the compact spinning yarns should be less than that on the ring spinning yarns.After testing the property of four kinds of yarns including compact spinningyarns spun with general roving, ring spinning yarns spun with general roving, compact spinning yams spun with tracer fiber roving and ring spinning yarns spun with tracer fiber roving, it is concluded that yarns spun with tracer fiber roving has similar property with yarns spun with general roving so that the yams spun with tracer fiber roving can be used to study the structure of compact spinning yams.The Hi-scope Video Microscope System is used to observe and study the form of tracer fibers in the yarns. The three-dimensional form of the tracer fibers in yarns is figured with a Matlab program and the result is gained that the tracer fiber helix in compact spinning yams is more regular than that in ring spinning yarns. The fiber migration of compact spun yams is weaker than that of ring spinning yarns. The radial twist distribution curves of two kinds of yarns is calculated and it is found that they have the similar changing trend except for that the twist of compact spinning yarns is smaller than that of ring spinning yams. The angles between the tracer fibers and axes of yams are measured and it is calculated that the degree of fiber orientation in compact spinning yams is higher than that in ring spinning yams. This, result gives the reason that why the compact spinning yarns has higher strength than the ring spinning yams.