限動(dong)芯(xin)(xin)棒(bang)連(lian)軋管工(gong)藝(yi)被稱(cheng)(cheng)作(zuo)“Retained mandrel mill”或“Multi-stand pipe mill”（簡稱(cheng)(cheng)MPM),前者是(shi)從芯(xin)(xin)棒(bang)運(yun)動(dong)受控這一特點出發的，故稱(cheng)(cheng)為“限動(dong)芯(xin)(xin)棒(bang)連(lian)軋管工(gong)藝(yi)”，后者是(shi)從Calmes 取名的“Multi-stand pilger mill”中“Pilger”變以“Pipe”演(yan)變而(er)來的。由于這一歷(li)史原因，這種軋機(ji)簡稱(cheng)(cheng)為 MPM軋機(ji)，而(er)不(bu)是(shi)RMM.
采用這種工藝軋管，連軋不銹鋼管外徑最大可達406mm(16英寸），最佳尺寸為339.3mm(13 3/8英寸）。該工藝的實質是：在整個軋制過程中，控制芯棒運動速度，使其保持恒定；借助于脫管機，在軋制過程結束時，將芯棒從荒管中抽出，使其與芯棒裝置一起返回。
1. MPM工(gong)藝設備特征(zheng)
a. MPM軋機的特征(zheng)
MPM軋(ya)機采(cai)用(yong)機械限(xian)(xian)動(dong)(dong)(dong)(dong)式(shi)芯棒速(su)(su)(su)度(du)(du)控制(zhi)裝(zhuang)置，芯棒的快速(su)(su)(su)動(dong)(dong)(dong)(dong)作（穿心棒、抽(chou)芯棒）及限(xian)(xian)動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作（軋(ya)制(zhi)時控制(zhi)芯棒速(su)(su)(su)度(du)(du)）靠(kao)36m長的大(da)齒(chi)條(tiao)(tiao)來實現(xian)。快速(su)(su)(su)動(dong)(dong)(dong)(dong)作由(you)(you)兩(liang)臺500kW直流電機分(fen)(fen)別(bie)驅(qu)動(dong)(dong)(dong)(dong)兩(liang)個齒(chi)輪(lun)(lun)，從齒(chi)條(tiao)(tiao)的上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)齒(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)。限(xian)(xian)動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作時，由(you)(you)8個齒(chi)輪(lun)(lun)（上(shang)下(xia)各4個）從齒(chi)條(tiao)(tiao)的上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)齒(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)，每個齒(chi)輪(lun)(lun)均(jun)由(you)(you)1臺110kW直流電機單獨傳動(dong)(dong)(dong)(dong)。芯棒運動(dong)(dong)(dong)(dong)方式(shi)的改變依靠(kao)氣動(dong)(dong)(dong)(dong)離合器分(fen)(fen)別(bie)接通(tong)或脫開相應(ying)的齒(chi)輪(lun)(lun)來實現(xian)。芯棒的快速(su)(su)(su)行(xing)程(cheng)(cheng)速(su)(su)(su)度(du)(du)為(wei)6m/s,限(xian)(xian)動(dong)(dong)(dong)(dong)速(su)(su)(su)度(du)(du)為(wei)0.2~0.5m/s,限(xian)(xian)動(dong)(dong)(dong)(dong)工(gong)作行(xing)程(cheng)(cheng)為(wei)5.0~5.2m.
在Dalmine公司進行試驗(yan)時(shi)，芯(xin)棒(bang)(bang)的(de)運動(dong)速度采用(yong)液壓控制。但(dan)因液壓系統控制芯(xin)棒(bang)(bang)速度不夠穩定，有芯(xin)棒(bang)(bang)斷(duan)續運動(dong)的(de)情況，隨后改(gai)為(wei)齒(chi)輪齒(chi)條(tiao)傳(chuan)動(dong)的(de)機械系統。
MPM的(de)(de)軋輥(gun)孔型采(cai)用比普通連軋機開口角稍小的(de)(de)封閉(bi)式圓(yuan)孔（帶(dai)弧(hu)形開口），可以采(cai)用較大的(de)(de)伸長率。
b. 脫(tuo)管機的特征(zheng)
MPM的(de)脫(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)與(yu)二輥(gun)(gun)式定徑(jing)(jing)機(ji)(ji)(ji)相同(tong)，由(you)于(yu)MPM主軋(ya)機(ji)(ji)(ji)的(de)第七、八(ba)機(ji)(ji)(ji)架(jia)的(de)壓下(xia)量很小，僅靠第七、八(ba)機(ji)(ji)(ji)架(jia)軋(ya)輥(gun)(gun)的(de)作用(yong)無法推送管(guan)(guan)子前進和(he)使管(guan)(guan)子從芯(xin)棒前端(duan)脫(tuo)(tuo)出，故在MPM工藝(yi)中設置幾(ji)架(jia)脫(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)，起脫(tuo)(tuo)管(guan)(guan)和(he)定徑(jing)(jing)的(de)作用(yong)。脫(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)軋(ya)輥(gun)(gun)直徑(jing)(jing)為(wei)720~850mm,輥(gun)(gun)身長420mm,第一(yi)(yi)、三架(jia)由(you)1臺450kW的(de)直流電(dian)機(ji)(ji)(ji)驅(qu)動(dong)，而第二架(jia)則單獨由(you)1臺同(tong)型(xing)號電(dian)機(ji)(ji)(ji)驅(qu)動(dong)。脫(tuo)(tuo)管(guan)(guan)速度必須按連軋(ya)原則確(que)定，并與(yu)MPM軋(ya)機(ji)(ji)(ji)的(de)第八(ba)機(ji)(ji)(ji)架(jia)保(bao)持電(dian)氣(qi)連鎖(suo)。脫(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)減徑(jing)(jing)率(lv)為(wei)3.5%~4.6%,孔型(xing)與(yu)一(yi)(yi)般(ban)二輥(gun)(gun)式定徑(jing)(jing)直機(ji)(ji)(ji)相同(tong)。
c. MPM工(gong)藝(yi)的芯棒運動特(te)征
軋制(zhi)(zhi)過程中，要(yao)控制(zhi)(zhi)芯棒(bang)(bang)的(de)速度(du)，使其處于恒定狀態。雖然芯棒(bang)(bang)也隨管(guan)子(zi)(zi)前進，但(dan)其前進速度(du)應遠小于管(guan)子(zi)(zi)的(de)速度(du)，軋制(zhi)(zhi)結束后被抽出返回。軋制(zhi)(zhi)28m長的(de)管(guan)子(zi)(zi)時，芯棒(bang)(bang)長度(du)為12m.芯棒(bang)(bang)為中空水(shui)冷(leng)芯棒(bang)(bang)，軋制(zhi)(zhi)結束后，芯棒(bang)(bang)溫度(du)為400℃,需要(yao)采用內外噴(pen)水(shui)使之(zhi)均(jun)勻冷(leng)卻。
2. 限動芯棒連(lian)軋管工藝技術發展的4個(ge)階段
不銹(xiu)鋼(gang)管(guan)(guan)(guan)(guan)(guan)限動芯棒(bang)連(lian)軋(ya)管(guan)(guan)(guan)(guan)(guan)工藝(yi)的(de)技(ji)術(shu)發(fa)(fa)(fa)展(zhan)(zhan)史應(ying)溯自1890年(nian)，Pfeiffer在一(yi)篇文章(zhang)中寫道：“1890年(nian)發(fa)(fa)(fa)明家Heckert 申(shen)請了(le)連(lian)軋(ya)技(ji)術(shu)專利(li)，該技(ji)術(shu)采用(yong)十架兩(liang)輥(gun)高速(su)軋(ya)機(ji)固定芯棒(bang)軋(ya)制空心管(guan)(guan)(guan)(guan)(guan)坯。可(ke)見在Calmes 多機(ji)架軋(ya)管(guan)(guan)(guan)(guan)(guan)機(ji)問世前80年(nian)，就已(yi)有(you)了(le)雛形。”1968年(nian)A.H.Calmes 取得(de)了(le)MPM連(lian)軋(ya)管(guan)(guan)(guan)(guan)(guan)工藝(yi)的(de)權(quan)利(li)，10年(nian)后，第一(yi)套MPM連(lian)軋(ya)管(guan)(guan)(guan)(guan)(guan)機(ji)在Dalmine Bergamo 鋼(gang)管(guan)(guan)(guan)(guan)(guan)廠投產，到2003年(nian)12月(yue)天(tian)津(jin)無縫(feng)不銹(xiu)鋼(gang)管(guan)(guan)(guan)(guan)(guan)廠三輥(gun)式(shi)限動芯棒(bang)連(lian)軋(ya)管(guan)(guan)(guan)(guan)(guan)機(ji)投產，已(yi)經歷(li)了(le)整整25年(nian)的(de)時間，和全浮動芯棒(bang)連(lian)軋(ya)管(guan)(guan)(guan)(guan)(guan)技(ji)術(shu)的(de)發(fa)(fa)(fa)展(zhan)(zhan)相比，這種工藝(yi)技(ji)術(shu)的(de)發(fa)(fa)(fa)展(zhan)(zhan)顯得(de)快多了(le)。這25年(nian)的(de)發(fa)(fa)(fa)展(zhan)(zhan)歷(li)程可(ke)劃(hua)分為四(si)個階段，如表22-3所示。
