Research On Drafting Force In Super High Draft Ring Spinning

In order to spin high counts yarns by heavy density roving, a new kind of drafting system with high draft ratio was needed, which can improve production efficiency in fore-spinning process. The most effective way is adding drafting zones to traditional ring spinning machines. Therefore, Jiangnan University and Changzhou Tonghe Textile Machinery CO. LTD developed TH558 super high draft ring spinning machine, which was equipped with four-line draft system(FLDS) and four aprons. The maximum draft ratio can reach to 250.However, the front draft zone(FDZ) worked as the main draft zone in FLDS, and larger draft ratio was distributed. For FDZ of FLDS, the friction field and drafting force changed, which would increase yarn unevenness. Thus, it is important to study the friction field and drafting force. For FLDS, both fiber distribution in draft zone and draft ratio as well as the contact of drafting component were intuitive factors influencing the friction field and drafting force. So,in this paper, the friction field and drafting force of the FDZ in FLDS was studied. The influence of draft ratio and the contact of drafting component on the friction field and drafting force were analyzed, and the relationship of drafting force and yarn properties was researched.First, by cut-middles method, the fiber distribution in FDZ of FLDS and three-lines draft system(TLDS) was studied. Both fiber distribution and the front fiber distribution as well as the back fiber distribution was compared to analyze the effect of drafting system on fiber distribution and drafting force. Then, the draft ratio of the FDZ in FLDS was changed, and fiber distribution and draft force were analysed to study the effect of draft ratio on drafting force. Cut-middles method was used to study fiber distribution and drafting force measurement were used to study drafting force. Finally, the pressure and deformation of the first middle top roller(FMTR) were studied. FMTR made from steel and sleeved carbon fiber were compared. During yarn spinning, numerical simulations of FMTR pressure and deformation were presented in ANSYS software and comparatively analyzed. The influence of FMTR material on draft force unevenness was studied and optimal FMTR can be obtained.In order to research the relationship between draft force unevenness and yarn unevenness,corresponding yarn qualities were compared. The results indicate that:Compared with TLDS, 9.7tex and thinner cotton yarns spun by FLDS have better yarn properties, since the middle draft zone of FLDS makes fiber strand structure become denser.For the FDZ of FLDS, as the draft ratio increase, the draft force decrease when the same fiber was feed into the FMTR. However, as the draft ration increase, the draft force increase when the same fiber was output from the front roller. The yarn unevenness decrease as well. The yarn unevenness changes corresponding with the draft force unevenness. Moreover, for 5.8and 4.9tex cotton yarn, yarns spun by FMTR made from sleeved carbon fiber have larger pressure and deformation at the middle of nipper bites of front middle roller and FMTR, and yarn evenness is better. For 3.9tex cotton yarns, at the middle of nipper bites of front middle roller and FMTR, FMTR made from steel has smaller pressure. But deformation of FMTR made from steel is larger, and yarn evenness is better.