Studies On Design, Manufacture And Applications Of Spinnerette For Melt-spinning Shaped Fibers

High-precision profiled spinneret is the starting point for developing shaped fibers belonging to differential fiber categories,thus in this dissertation a systematic study has been made on designing,processing and the corresponding fiber exploitation for the profiled spinnerets.Firstly,basing on the structure analysis,the working mechanism as well as the corrective theory of twist drill,the experimental investigations were made on the spinneret counterbore machining technology,and the deviation problem was found inevitable in machining spinneret counterbore of large aspect ratio with the micro-diameter drill.However, farther theoretical and experimental analysis showed that through a periodic and constant drill feeding,a very good corrective effect could be achieved.On the other hand,the cutting consumption was optimized and a modification was made for the micro-diameter drill.Secondly,a specialized Numerically Controlled Electrical Discharge Machining(EDM) was developed for the production of profiled spinneret capillaries,including the guider for precisely positioning a number of electrodes,the electrode rotating center for efficiently controlling the size of spinneret capillaries,which was realized under a programming controlled five-axle linkage system.Subsequently,utilizing the basic unit design concept,four complex spinneret capillaries were successfully processed via combination,and the key technologies for machining profiled spinerrete capillaries were obtained.Thereafter,a numerical simulation for extruding silver electrode was made and the influences of friction force on extruding pressure,stress distribution and punch dimensions were discussed,providing a theoretical support for the die structural design.On the above basis,the trilobal die was developed and the silver electrode for making trilobal spinerrete capillaries was pressed and shaped on a self-designed equipment,and the production has been pushed into industrialization.The random inspections for the resulted capillaries showed that the enterprise standards could be fulfilled. Moreover,through studies on auto-focusing,image processing,extraction and measurement of the feature parameters and automatic positioning with the spinneret capillaries,an automatic intelligent detection system with optical-mechanical-electronic integration was successfully developed.The device can solve the problem of false retrieve and slip testing existed at present detecting machines,increasing test accuracy and efficiency simultaneously.Thirdly,the tbrming theory of rectangular fiber was studied.The spinning dynamic model for rectangular fiber was established above all. Then the cross-section deformation dynamic model of shaped fibers was also established according to the energy dissipation law.Sequentially,flat fiber deformation process was simulated and the results were consistent with those of Takarada et al.Moreover,the change of spinning temperature,velocity,tension and shaped degree along spinning path of flat fiber were simulated,which showed that rectangular length-width ratio of the spinneret capillaries,spinning temperature,the starting point of quenching air and quenching speed would draw different levels of impacts on the fiber’s profile degree.Guided by the above flat fiber deformation theory,high profiled flat fibers were produced in Tianjin Petro-chemical Plant,and the fibers showed a length-width ratio of 7.738 which was consistent well with the predicted results by simulation.Basing on the studies of flat fibers,the changes of the fiber shaped degree with spinning parameters were experimented for trilobal, pentalobal and cross fibers respectively.The results showed that the fiber shaped degree increased with the increasing pump delivery whereas decreased with the increasing spinning temperature.At the same time, simulations were made for the change of profile degree along the spinning paths for those three kinds of shaped fibers and mass production were then brought into effect for verification.The results indicated that theoretical predictions were fairly close to the actually measured values. Therefore,the established profiled fiber deformation models were suitable for simulating the forming process of trilobal,pentalobal and cross fibers and the method of deciding deforming coefficients for those three fibers was reasonable and feasible.Finally,application researches of profiled spinneret design were made to develop several special section fibers.Primarily,three sets of programmes were planned to produce profiled multi-channeled hollow fibers in which copper electrode was used for producing the spinerrete capillaries.Eventually,16 hole- profiled filaments with a denier of25dtex were obtained successfully,implying the validity of design idea of shaped spinneret capillaries based on basic unit concept proposed above. Furthermore,pure silver electrode with good discharge and mechanical properties was adopted to make the horseshoe shaped fine silver electrode with a diameter of only 0.5mm.Then multi-channeled high precision spinneret capillaries were finally realized through NC assembling technology and for the first time three-dimensional crimp profiled fiber with a denier per filament of 15dtex was obtained.Thereafter the corresponding industrial fiber production was carried out smoothly and the fiber quality could meet the enterprise requirements.Sequentially,fine denier and highly profiled pentalobal fibers were developed.After analyzing the poor processibiiity of fibers with the mentioned profiled fiber formation theory,,adopting thermal insulation method and using upper side quenching devices coordinately as well as controlling spinning parameters properly,the profiled pentalobal fibers with an average length-width ratio of 1.78(per leaf) was achieved by the mass production at last.As an application of the profiled spinneret design and process theory,PTT/PET side-by-side complex shaped spinnerets,which could not be produced so far,were exploited.The earlier designed spinneret cavity was composed of two parallel straight holes,and spinning experiments showed that the resulted complex profiled fibers had poor interface bonding force.The relative spinning process simulation indicated that with that straight cavity the melt binding would happen at a certain position from the spinneret just because of drafting but not swelling effects.Therefore,in this study the spinneret channel were modified to tilt 30°and detailed theoretical study and practical development were carded out for the design schemes,processing techniques and machining tools.Finally high precision complex shaped spinnerets with two-tilt channels were processed to success,which was expected to provide technology supports for further development of PTT/PET side-by-side complex shaped fibers with excellent performances.All in all,through studies of the spinneret’s processing,shaped fiber formation theory and mass production of the profiled fibers,it is now possible for the profiled fiber production from quantitative groping to qualitative controlling.It is believed that the work in this dissertation has contributed something to the rapid development of the profiled fibers in recent years within China.