Study On The Uniformity Of Fiber Web Based On Positive Drawing

With the progresses of spunbond technology and the increasing market demand, people have made a claim for a higher production quality. For spunbonded nonwovens, the uniformity is very important, it affects other properties of the product and the expansion of product areas. However, limiting to the experimental conditions, the theoretical study of the spunbond technology always lags behind the production, and most of the researches are not systemic and intensiveFirstly, based on the work of other predecessors, this papr did research on effect which the four process parameters have on the uniformity of fiber web by Single factor analysis of variance, the four process parameters are polymer-melt temperature, the speed of wind for sucking monomer, stretching pressure. The level of significance of every process parameter was fixed by analysis of varianceSecondly, the interpolating function was used to make the mathematical relationship between stretching pressure and coefficient of variation of the surface density. The functional images was mapped by MATLAB, then it could be used to fix the CV of the surface density of different stretching pressures theoretically, which can be used to forecast the actual production.Thirdly, Two-dimensional single-precision, Separating Solver and the realizable k-e model were used to simulate the the air flow field of outlet in wide slot mechanism of drawing of spunbonding, the boundary conditions were also considered at the same time. Convergent speed and accuracy of different turbulence models are putted together to make comparison. Second Order Upwind was selected in Discrete Form, Convergence criteria was setted as 10^-5, and the SIMPLEC was selected as well.Finally, the simulational results were compared with engineering survey and theoretical calculation, they were proved to be correct. After this, velocity distribution, pressure distribution, distribution of velocity and pressure at outlet with four different stretching pressures were simulated to further analyse the influence, which the different stretching pressures have on the uniformity.