一、紗線捻度是什么意思
紗線捻度是指為使紗線具有一(yi)定的強力、彈性(xing)、伸長、光(guang)澤(ze)、手(shou)感等物理機械性(xing)能,必須通過(guo)加(jia)捻(nian)改變棉紗,由(you)纖(xian)維結(jie)構(gou)來實現紗線(xian)加(jia)捻(nian),其實就(jiu)是利用棉紗橫截面(mian)間產生相對角(jiao)位移,使原來伸直平行之纖(xian)維與紗軸(zhou)發(fa)生傾斜來改變紗線(xian)結(jie)構(gou),粗條在加(jia)捻(nian)過(guo)程由(you)寬度(du)逐(zhu)漸收縮,兩側(ce)逐(zhu)漸折迭(die)而卷入(ru)紗線(xian)條中心,形(xing)成(cheng)加(jia)捻(nian)三(san)角(jiao)形(xing),在加(jia)捻(nian)三(san)角(jiao)形(xing)中,棉條的寬度(du)和截面(mian)發(fa)生變化,從扁平帶狀(zhuang),逐(zhu)漸成(cheng)圓柱形(xing)的紗。
二、紗線捻度的測定方法有哪些
1、退捻法:用于短纖(xian)維(wei)純紡、混(hun)紡(環(huan)錠(ding)(ding)紡、走錠(ding)(ding)紡、翼錠(ding)(ding)紡)的股線中(zhong)較粗者(zhe)和加捻的長(chang)絲。退(tui)捻至纖(xian)維(wei)平行(xing),計(ji)數(shu)紗線單位長(chang)度的退(tui)捻轉數(shu)。
2、退捻加捻法:短纖維(wei)傳統紡紗中(zhong)較(jiao)細(xi)的紗線,用退(tui)捻(nian)(nian)(nian)(nian)再反向(xiang)加(jia)捻(nian)(nian)(nian)(nian)使(shi)紗線伸長后又(you)縮回(hui)到(dao)原長,用所加(jia)轉數的半(ban)作(zuo)此(ci)段(duan)紗線捻(nian)(nian)(nian)(nian)數。近來(lai)又(you)發(fa)展了二次退(tui)捻(nian)(nian)(nian)(nian)加(jia)捻(nian)(nian)(nian)(nian)法、三次退(tui)捻(nian)(nian)(nian)(nian)加(jia)捻(nian)(nian)(nian)(nian)法及四次退(tui)捻(nian)(nian)(nian)(nian)加(jia)捻(nian)(nian)(nian)(nian)法等。目(mu)的是消(xiao)除纖維(wei)須條(tiao)反向(xiang)加(jia)捻(nian)(nian)(nian)(nian)時(shi)結構(gou)的變化。但也可(ke)能引起(qi)紗線結構(gou)變化而使(shi)測試(shi)結果(guo)失準。
3、反光法:用平行光束照射紗線,測量反射光峰值(zhi)偏(pian)轉的角(jiao)度,占計加捻紗線表(biao)層螺(luo)旋(xuan)角(jiao)計算捻度。
對(dui)于轉杯紡、靜電(dian)窈(yao)、噴氣紡、賽洛(luo)紡、自(zi)捻紡等新型紗線的(de)捻度,由于結構不同,特(te)別(bie)紗線皮芯捻數不同甚至不同捻向。應設(she)法分層(ceng)分別(bie)測(ce)試(shi)并分別(bie)發展不同的(de)測(ce)試(shi)方法。