限(xian)動(dong)芯(xin)棒連軋(ya)管工(gong)藝(yi)被稱(cheng)作“Retained mandrel mill”或“Multi-stand pipe mill”（簡稱(cheng)MPM),前者(zhe)是(shi)從(cong)芯(xin)棒運動(dong)受控這(zhe)一特點出發的(de)，故稱(cheng)為(wei)“限(xian)動(dong)芯(xin)棒連軋(ya)管工(gong)藝(yi)”，后者(zhe)是(shi)從(cong)Calmes 取(qu)名(ming)的(de)“Multi-stand pilger mill”中“Pilger”變以“Pipe”演變而來的(de)。由(you)于這(zhe)一歷史原因，這(zhe)種軋(ya)機簡稱(cheng)為(wei) MPM軋(ya)機，而不是(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工藝設備(bei)特征(zheng)
a. MPM軋機的特征
MPM軋機(ji)(ji)采用機(ji)(ji)械限動(dong)(dong)(dong)(dong)(dong)式芯(xin)棒(bang)速(su)(su)(su)度(du)(du)控制(zhi)裝置，芯(xin)棒(bang)的快(kuai)速(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)作（穿心(xin)棒(bang)、抽芯(xin)棒(bang)）及限動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作（軋制(zhi)時(shi)控制(zhi)芯(xin)棒(bang)速(su)(su)(su)度(du)(du)）靠36m長的大齒(chi)(chi)(chi)(chi)條(tiao)來實(shi)(shi)現。快(kuai)速(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)作由(you)兩臺(tai)500kW直流電機(ji)(ji)分別驅動(dong)(dong)(dong)(dong)(dong)兩個(ge)齒(chi)(chi)(chi)(chi)輪，從(cong)齒(chi)(chi)(chi)(chi)條(tiao)的上(shang)下側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)條(tiao)運動(dong)(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作時(shi)，由(you)8個(ge)齒(chi)(chi)(chi)(chi)輪（上(shang)下各4個(ge)）從(cong)齒(chi)(chi)(chi)(chi)條(tiao)的上(shang)下側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)條(tiao)運動(dong)(dong)(dong)(dong)(dong)，每個(ge)齒(chi)(chi)(chi)(chi)輪均由(you)1臺(tai)110kW直流電機(ji)(ji)單獨傳(chuan)動(dong)(dong)(dong)(dong)(dong)。芯(xin)棒(bang)運動(dong)(dong)(dong)(dong)(dong)方式的改變依靠氣動(dong)(dong)(dong)(dong)(dong)離合器(qi)分別接通或脫開(kai)相應的齒(chi)(chi)(chi)(chi)輪來實(shi)(shi)現。芯(xin)棒(bang)的快(kuai)速(su)(su)(su)行(xing)程速(su)(su)(su)度(du)(du)為6m/s,限動(dong)(dong)(dong)(dong)(dong)速(su)(su)(su)度(du)(du)為0.2~0.5m/s,限動(dong)(dong)(dong)(dong)(dong)工作行(xing)程為5.0~5.2m.
在Dalmine公司(si)進行試驗時，芯棒(bang)的(de)運動速(su)度(du)采用(yong)液壓(ya)控制(zhi)。但因液壓(ya)系(xi)統控制(zhi)芯棒(bang)速(su)度(du)不夠穩定，有芯棒(bang)斷續運動的(de)情況，隨后(hou)改為齒輪齒條(tiao)傳(chuan)動的(de)機械系(xi)統。
MPM的(de)軋輥孔(kong)型采用比(bi)普通連軋機開口角(jiao)稍小的(de)封閉式圓孔(kong)（帶弧形開口），可(ke)以采用較(jiao)大的(de)伸長率。
b. 脫管機的特征
MPM的(de)脫(tuo)(tuo)管(guan)(guan)(guan)機(ji)(ji)與(yu)(yu)二(er)(er)輥(gun)式(shi)定徑(jing)(jing)機(ji)(ji)相(xiang)同，由(you)于(yu)MPM主軋(ya)(ya)機(ji)(ji)的(de)第七、八(ba)機(ji)(ji)架(jia)(jia)的(de)壓下(xia)量(liang)很(hen)小，僅靠第七、八(ba)機(ji)(ji)架(jia)(jia)軋(ya)(ya)輥(gun)的(de)作用(yong)無法(fa)推送管(guan)(guan)(guan)子(zi)前進(jin)和使(shi)管(guan)(guan)(guan)子(zi)從芯(xin)棒前端脫(tuo)(tuo)出(chu)，故在MPM工藝中設(she)置(zhi)幾架(jia)(jia)脫(tuo)(tuo)管(guan)(guan)(guan)機(ji)(ji)，起脫(tuo)(tuo)管(guan)(guan)(guan)和定徑(jing)(jing)的(de)作用(yong)。脫(tuo)(tuo)管(guan)(guan)(guan)機(ji)(ji)的(de)軋(ya)(ya)輥(gun)直(zhi)徑(jing)(jing)為(wei)720~850mm,輥(gun)身長420mm,第一(yi)(yi)、三架(jia)(jia)由(you)1臺450kW的(de)直(zhi)流電(dian)機(ji)(ji)驅(qu)動，而第二(er)(er)架(jia)(jia)則(ze)單(dan)獨由(you)1臺同型號電(dian)機(ji)(ji)驅(qu)動。脫(tuo)(tuo)管(guan)(guan)(guan)速度必須按連(lian)軋(ya)(ya)原(yuan)則(ze)確定，并與(yu)(yu)MPM軋(ya)(ya)機(ji)(ji)的(de)第八(ba)機(ji)(ji)架(jia)(jia)保(bao)持電(dian)氣連(lian)鎖。脫(tuo)(tuo)管(guan)(guan)(guan)機(ji)(ji)的(de)減徑(jing)(jing)率為(wei)3.5%~4.6%,孔型與(yu)(yu)一(yi)(yi)般(ban)二(er)(er)輥(gun)式(shi)定徑(jing)(jing)直(zhi)機(ji)(ji)相(xiang)同。
c. MPM工藝的芯棒運動特征(zheng)
軋(ya)制過程中，要(yao)控制芯(xin)棒(bang)(bang)(bang)(bang)的速度(du)，使其處于恒(heng)定(ding)狀態(tai)。雖然(ran)芯(xin)棒(bang)(bang)(bang)(bang)也隨管子前(qian)進，但(dan)其前(qian)進速度(du)應遠小(xiao)于管子的速度(du)，軋(ya)制結(jie)束后被抽出返(fan)回。軋(ya)制28m長的管子時，芯(xin)棒(bang)(bang)(bang)(bang)長度(du)為12m.芯(xin)棒(bang)(bang)(bang)(bang)為中空水(shui)冷(leng)芯(xin)棒(bang)(bang)(bang)(bang)，軋(ya)制結(jie)束后，芯(xin)棒(bang)(bang)(bang)(bang)溫度(du)為400℃,需(xu)要(yao)采用內外噴水(shui)使之(zhi)均(jun)勻冷(leng)卻(que)。
2. 限動芯(xin)棒連(lian)軋管工(gong)藝技術發展的(de)4個階段
不銹(xiu)(xiu)鋼(gang)管(guan)(guan)(guan)限(xian)動芯(xin)(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)工(gong)(gong)(gong)藝的(de)(de)技(ji)術(shu)發展史應溯(su)自(zi)1890年(nian)，Pfeiffer在一(yi)篇文章中寫(xie)道：“1890年(nian)發明家Heckert 申請(qing)了連(lian)軋(ya)(ya)技(ji)術(shu)專利，該技(ji)術(shu)采用十架(jia)兩輥高速軋(ya)(ya)機(ji)(ji)固定芯(xin)(xin)棒軋(ya)(ya)制(zhi)空心管(guan)(guan)(guan)坯。可見在Calmes 多機(ji)(ji)架(jia)軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)問世前80年(nian)，就已(yi)有(you)了雛(chu)形。”1968年(nian)A.H.Calmes 取得了MPM連(lian)軋(ya)(ya)管(guan)(guan)(guan)工(gong)(gong)(gong)藝的(de)(de)權利，10年(nian)后(hou)，第一(yi)套(tao)MPM連(lian)軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)在Dalmine Bergamo 鋼(gang)管(guan)(guan)(guan)廠投(tou)產(chan)，到2003年(nian)12月天津無縫不銹(xiu)(xiu)鋼(gang)管(guan)(guan)(guan)廠三輥式限(xian)動芯(xin)(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)投(tou)產(chan)，已(yi)經(jing)歷(li)了整整25年(nian)的(de)(de)時(shi)間(jian)，和(he)全浮動芯(xin)(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)技(ji)術(shu)的(de)(de)發展相比，這種工(gong)(gong)(gong)藝技(ji)術(shu)的(de)(de)發展顯得快(kuai)多了。這25年(nian)的(de)(de)發展歷(li)程可劃分為四個階段，如表22-3所示。
