Model Of Polyester Melt Spinning And Mechanical Performance Prediction

With the development of melt spinning technology, new materials, new technology, and new products emerge in endlessly, it is need to combine with the practical application to carry out the system research of spinning forming dynamics model and provided powerful theoretical support for the actual production and processing.In view of the shortcomings of existing research on polyester melt spinning modeling, such as unsystematic dynamics equations, incompleted model parameters and impractical model, the dynamic models in the existing literatures were summarized, the representative parameter equations (such as constitutive equation, orientation equation, crystallization equation, etc.) were choosed, and the converse-fit method was adopted to obtain the unknown parameters and physical parameters. The dynamic model of polyester POY (Partially Oriented Yarn) melt spinning was improved and verified in this paper. It was proved to be the guidance of polyester filament melt spinning process. Combined with the programming language Matlab, Fourth order Runge-Kutta algorithm was applied to get the temperature, velocity, orientation, crystallization of polyester filament along the spinning line. In order to verify the accuracy of the proposed models, polyester filament spinning process in Baihong Co. Ltd was studied and it was found that the bias between the numerical simulation and actual measured values was within10%, and the model was proved to be able to forecast the actual processing. The influence of spinning process conditions on the structure of fiber was also explored. The orientation and crystallization of polyester POY increase with the reduction in the pump mass; The orientation of polyester POY rise with increase of annealed zone temperature, and the crystallinity increases at the same time for the inducement of high orientation to easy nuclei forming at higher temperature; As the quenching air speed increases, the fiber orientation increases and the crystallinity decreases; With increase of the spinning speed, both orientation and crystallinity of polyester POY increase.Based on previous research on the hot-roller process and the dynamic model of POY melt spinning, FDY (Fully Drawn Yarn) stretching hot-roller model was built. Converse-fit method was used to get the unknown parameters and the FDY process was simulated. The simulation results are consistent with the actual production, which prove the model can be used to advise the actual production. The influence of hot-roller conditions on the structure of fiber was also explored. As GR1speed increases, the orientation and crystallinity of polyester FDY reduce; As GR1temperature increases, the fiber orientation doesn’t change significantly at the GR1, while it increases greatly at the GR2; The fiber orientation and crystallinity rise at the GR1and GR2, with GR2speed or temperature increases.According to the previous model can only calculate the fiber structure parameters through the spinning process, but can’t predict the final performance of fiber, an engineering melt spinning model combined with the dynamic model and the mechanical model was built in this paper. It can directly reflect not only the internal mechanism of spinning process, but also the change of fiber properties through the process adjustment. It builds a bridge of the relationship between spinning process and fiber properties. Based on the measured S-S (Stress-Strain) curves of filaments and the Optimization algorithm combined the Levenberg-Marquardt method (LM) with General Global Optimization algorithm (Universal Global Optimization-UGO), a nonlinear four components model was proposed and the parameters of the model were obtained by the1stOpt software. The spinning process-structure-performance quantitative calculation was established. It can be used to optimize the technology of normal product process to improve the fiber quality, and lay the foundation of the development of new technology and new product at the same time.In order to verify the universality of the model and the engineering application capability, the POY (180dtex/144f) spinning line L8(1-12spinning position) and FDY (55dtex/24f) spinning line L3(27-30spinning positions) of Baihong Co. Ltd were choosed as the simulated cases. It was found that the bias between simulated and measured filament stractures and properties was within10%, which proves the model has widely accuracy. For the adjustment of process parameters, as increase the quenching air speed for POY process and the second hot-roller temperature for FDY process respectively, it was found that the change of fiber orientation and crystallinity had an upward trend, and the fiber’s strength and elongation are better than that before the adjustment. The simulation and the measured value are not only in consistent trend, but also the numerical difference was not significant, which indicates that the model has the ability to guide the actual process.