Experimental Verification And Analysis On Splicing Process Based On Transient Flow Field Simulation

With the development of national economy and the continuous improvement of people’sliving standards, the knotless yarn of high quality is demanded rapidly. Air splicer is a pneumaticdevice joining two yarn ends by mingling of the fibers composing the yarn, resulting incontinuity of the yarn itself and giving remarkable benefits in quality and distinct advantages inall subsequent stages of manufacture. Air splicing is a kind of advanced technology in textilefield for producing knotless yarns, which uses compressed air to drive yarns to do the untwistand twist work in sequence and finally achieve the knot-free connection. Proper preparation andmingling of yarn ends have significant effects on a joint’s strength and appearance, while theeffect of untwisting and twisting is determined by the processing parameters such as opening airpressure, ends preparation blast time, splicing blast duration and ends overlap.In this paper, the importance of fiber splicing in the yarn preparation process is expoundedat first. Detailed comparison between different fiber joint ways are carried on and the applicationbackground of air splicing technology is introduced briefly. The domestic and foreign studies inthe field of mingling chamber and vortex nozzle are analyzed and the significance of researchand development on air splicing technology is put forward.Next, the grid division of the mingling chamber is completed after3D geometric modeling,and the flow fields are analyzed by using the CFD method. The establishment, development andstability of air flow in the mingling chamber during transient flow process are discussed. Theregularities of distribution of related physical quantities such as air pressure field and velocityfield are carried out to explore the effect and mechanism of air flow on yarn joining. It provides atheoretical reference for the effective assessment of fiber mingling experiment.Once more, in order to verify the validity of the numerical simulation, a splice testingplatform is established based on the isothermal discharge method. Key factors such as openingair pressure, ends preparation blast time, splicing blast duration and ends overlap that influence operating properties of working time, air consumption and mass flow rate during yarn joining areanalyzed, and some untwisted and twisted yarn samples are achieved.At last, the impact of the state of ends preparation under the condition of differentuntwisting process parameters on joint quality is analyzed. Base on the response surfacemethodology, Minitab software is applied to do experimental study on splicing effects.Mathematics model among the splicing result and the splicing pressure, splicing time, endsoverlap, three significant effect factors is established. The study makes detailed analysis of theaffect factors to the splicing result’s interaction influences rules, and does optimization to obtainthe optimal processing parameters. It provides theory and application guide for improving thequality of yarn splicing.