目(mu)前采(cai)用(yong)的有三(san)種芯(xin)棒操(cao)(cao)作(zuo)(zuo)方式。早期(qi)的三(san)輥(gun)軋管機均采(cai)用(yong)全浮(fu)芯(xin)棒，即使在今天，仍(reng)有一部(bu)分機組(zu)采(cai)用(yong)全浮(fu)芯(xin)棒操(cao)(cao)作(zuo)(zuo)。但是，全浮(fu)芯(xin)棒操(cao)(cao)作(zuo)(zuo)方式有如下(xia)缺點：
（1）軋(ya)制特厚壁管時(shi)不易(yi)脫棒(bang)；
（2）對各種尺寸的(de)毛管(guan)均需要配置再加熱(re)爐；
（3）軋制薄壁管時易產生的金屬扭曲和表面缺陷。由于存在上述問題導致限動芯棒和回退芯棒操作方式的開發。
以(yi)下是三種不同芯棒操作方式的簡述。
1. 全浮芯棒
采用(yong)全浮芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)操(cao)作方(fang)式時，荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)被撥入(ru)(ru)(ru)(ru)到(dao)荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)前(qian)(qian)的人口(kou)臺，落到(dao)和軋(ya)(ya)機(ji)中心(xin)線一致的U形槽里。氣動壓(ya)管(guan)(guan)器壓(ya)在(zai)荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)上(shang)，將其(qi)夾(jia)緊，芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)將芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)穿入(ru)(ru)(ru)(ru)荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)內。一旦芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)完全穿入(ru)(ru)(ru)(ru)，壓(ya)管(guan)(guan)器就松開(kai)，于是，荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)連同芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)一并(bing)向軋(ya)(ya)輥(gun)方(fang)向送去(qu)。如果荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)不易(yi)喂(wei)入(ru)(ru)(ru)(ru)軋(ya)(ya)機(ji)，就用(yong)荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)在(zai)后面(mian)(mian)推(tui)(tui)下，以幫助荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)喂(wei)入(ru)(ru)(ru)(ru)。當荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)開(kai)始軋(ya)(ya)制時，荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)和芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)便(bian)返回到(dao)初始位(wei)(wei)置(zhi)。但是，當采用(yong)小直徑芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)軋(ya)(ya)管(guan)(guan)時，荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)推(tui)(tui)入(ru)(ru)(ru)(ru)機(ji)可保(bao)留在(zai)前(qian)(qian)位(wei)(wei)，充當導(dao)衛，防止芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)抖動。荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)延伸后，荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)和芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)一起通過軋(ya)(ya)機(ji)向前(qian)(qian)移動軋(ya)(ya)制終了時，后臺輥(gun)子升起，將毛管(guan)(guan)及芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)送到(dao)輸出(chu)輥(gun)道(dao)。然后，從輸出(chu)輥(gun)送到(dao)脫(tuo)棒(bang)(bang)(bang)(bang)機(ji)，將芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)從毛管(guan)(guan)中脫(tuo)出(chu)。脫(tuo)棒(bang)(bang)(bang)(bang)后，芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)先冷卻，再送到(dao)軋(ya)(ya)管(guan)(guan)機(ji)前(qian)(qian)臺，以備再用(yong)。荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)則由輥(gun)道(dao)送走(zou)，進行下一步加工。采用(yong)全浮棒(bang)(bang)(bang)(bang)操(cao)作方(fang)式時，軋(ya)(ya)機(ji)生產率最高，因此，下一根芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)的前(qian)(qian)端實際上(shang)可以跟在(zai)正(zheng)在(zai)軋(ya)(ya)制的前(qian)(qian)一根荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)的芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)的后面(mian)(mian)。這是可能的，因為(wei)在(zai)前(qian)(qian)一根荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)軋(ya)(ya)完以前(qian)(qian)，后一根荒(huang)(huang)(huang)(huang)(huang)(huang)(huang)管(guan)(guan)可以放在(zai)前(qian)(qian)臺上(shang)、并(bing)穿好(hao)芯(xin)(xin)(xin)棒(bang)(bang)(bang)(bang)。
2. 回退芯棒
回(hui)(hui)退(tui)(tui)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)操作方(fang)式(shi)和(he)浮動芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)一(yi)樣使(shi)用同一(yi)荒(huang)管(guan)(guan)(guan)(guan)(guan)推(tui)(tui)人(ren)機(ji)與(yu)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)機(ji)，但是芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)機(ji)上加(jia)了一(yi)套(tao)裝置(zhi)(zhi)，可將芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)的后(hou)(hou)端固定在(zai)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)機(ji)上并使(shi)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)回(hui)(hui)轉(zhuan)。荒(huang)管(guan)(guan)(guan)(guan)(guan)在(zai)前(qian)臺的初始(shi)位置(zhi)(zhi)和(he)夾緊與(yu)全浮芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)操作方(fang)式(shi)一(yi)樣。然而，在(zai)插(cha)入(ru)(ru)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)時(shi)，不僅芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)頭部穿(chuan)(chuan)過荒(huang)管(guan)(guan)(guan)(guan)(guan)，而且(qie)芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)要穿(chuan)(chuan)過軋(ya)(ya)(ya)機(ji)，伸出軋(ya)(ya)(ya)輥(gun)臺肩約(yue)3.5m。當芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)到達此(ci)位置(zhi)(zhi)后(hou)(hou)，芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)開始(shi)回(hui)(hui)轉(zhuan)，直到荒(huang)管(guan)(guan)(guan)(guan)(guan)接(jie)觸軋(ya)(ya)(ya)輥(gun)后(hou)(hou)一(yi)段時(shi)間才停止(zhi)。當芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)推(tui)(tui)入(ru)(ru)機(ji)到達行程終點時(shi)，壓管(guan)(guan)(guan)(guan)(guan)器松(song)開，荒(huang)管(guan)(guan)(guan)(guan)(guan)推(tui)(tui)入(ru)(ru)機(ji)啟動前(qian)進。于是，荒(huang)管(guan)(guan)(guan)(guan)(guan)喂入(ru)(ru)軋(ya)(ya)(ya)機(ji)。軋(ya)(ya)(ya)制(zhi)開始(shi)后(hou)(hou)，芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)開始(shi)回(hui)(hui)退(tui)(tui)。其回(hui)(hui)退(tui)(tui)速度(du)(du)與(yu)荒(huang)管(guan)(guan)(guan)(guan)(guan)的行程長(chang)度(du)(du)及(ji)前(qian)進速度(du)(du)有關，以便在(zai)軋(ya)(ya)(ya)制(zhi)過程結(jie)束(shu)，當毛(mao)管(guan)(guan)(guan)(guan)(guan)離開軋(ya)(ya)(ya)輥(gun)時(shi)，芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)正好從荒(huang)管(guan)(guan)(guan)(guan)(guan)中抽(chou)出。見圖(tu)6-49。然后(hou)(hou)，毛(mao)管(guan)(guan)(guan)(guan)(guan)從軋(ya)(ya)(ya)機(ji)運走，進行下步加(jia)工(gong)，而芯(xin)(xin)(xin)(xin)(xin)棒(bang)(bang)(bang)高速返回(hui)(hui)其初始(shi)位置(zhi)(zhi)以備穿(chuan)(chuan)入(ru)(ru)下一(yi)根(gen)毛(mao)管(guan)(guan)(guan)(guan)(guan)。
3. 限動芯棒
限動芯(xin)(xin)(xin)棒(bang)(bang)操(cao)作(zuo)法是(shi)全浮芯(xin)(xin)(xin)棒(bang)(bang)和(he)回退芯(xin)(xin)(xin)棒(bang)(bang)操(cao)作(zuo)法的(de)折中方(fang)法。采用這種方(fang)法時(shi)(shi)，芯(xin)(xin)(xin)棒(bang)(bang)的(de)尾端固定在(zai)芯(xin)(xin)(xin)棒(bang)(bang)推(tui)入(ru)機上，并可回轉。這和(he)回退芯(xin)(xin)(xin)棒(bang)(bang)操(cao)作(zuo)方(fang)式一樣，不同的(de)是(shi)，鋼(gang)管(guan)軋(ya)制時(shi)(shi)芯(xin)(xin)(xin)棒(bang)(bang)向前移動。在(zai)軋(ya)制結(jie)束時(shi)(shi)，芯(xin)(xin)(xin)棒(bang)(bang)從(cong)毛管(guan)上脫出(chu)(chu)。當荒管(guan)在(zai)前臺被夾緊時(shi)(shi)，穿(chuan)入(ru)芯(xin)(xin)(xin)棒(bang)(bang)，直(zhi)到(dao)(dao)(dao)芯(xin)(xin)(xin)棒(bang)(bang)前端伸(shen)出(chu)(chu)軋(ya)輥臺肩(jian)約(yue)0.3m左右為止。插入(ru)芯(xin)(xin)(xin)棒(bang)(bang)時(shi)(shi)，芯(xin)(xin)(xin)棒(bang)(bang)開(kai)始回轉，直(zhi)到(dao)(dao)(dao)荒管(guan)接觸(chu)軋(ya)輥后一段時(shi)(shi)間才停(ting)止。芯(xin)(xin)(xin)棒(bang)(bang)到(dao)(dao)(dao)位后，壓(ya)管(guan)器松開(kai)，荒管(guan)推(tui)入(ru)機將荒管(guan)推(tui)向軋(ya)輥，直(zhi)到(dao)(dao)(dao)軋(ya)制過程開(kai)始為止。軋(ya)制過程中，芯(xin)(xin)(xin)捧以低(di)于(yu)毛管(guan)軸向輸出(chu)(chu)速(su)度的(de)速(su)度和(he)軋(ya)件一起(qi)前進。軋(ya)制周期結(jie)束時(shi)(shi)，毛管(guan)從(cong)芯(xin)(xin)(xin)棒(bang)(bang)上脫出(chu)(chu)，然后，芯(xin)(xin)(xin)棒(bang)(bang)高速(su)返回其(qi)初(chu)始位置(zhi)。
三種(zhong)芯(xin)棒(bang)(bang)(bang)(bang)操(cao)作(zuo)(zuo)方(fang)式的(de)比較。在采(cai)用回退芯(xin)棒(bang)(bang)(bang)(bang)與限動(dong)芯(xin)棒(bang)(bang)(bang)(bang)操(cao)作(zuo)(zuo)方(fang)式的(de)工廠，只有生產D/t小(xiao)于7.5的(de)鋼管(guan)(guan)時才采(cai)用回退芯(xin)棒(bang)(bang)(bang)(bang)操(cao)作(zuo)(zuo)方(fang)式，而當生產D/t大于7.5的(de)鋼管(guan)(guan)時采(cai)用限動(dong)芯(xin)棒(bang)(bang)(bang)(bang)操(cao)作(zuo)(zuo)方(fang)式。顯(xian)然，采(cai)用回退和限動(dong)芯(xin)棒(bang)(bang)(bang)(bang)操(cao)作(zuo)(zuo)方(fang)式時，軋機產量(liang)比采(cai)用全浮芯(xin)棒(bang)(bang)(bang)(bang)時低，因為，下一(yi)根荒管(guan)(guan)撥入到前臺之(zhi)前，在用的(de)芯(xin)棒(bang)(bang)(bang)(bang)必須返回其初始(shi)位置(zhi)。同時，芯(xin)棒(bang)(bang)(bang)(bang)的(de)冷(leng)卻不充分，芯(xin)棒(bang)(bang)(bang)(bang)壽命不長。
