限動(dong)芯(xin)(xin)棒連軋(ya)(ya)(ya)管工藝被稱(cheng)(cheng)作“Retained mandrel mill”或“Multi-stand pipe mill”（簡稱(cheng)(cheng)MPM),前者是(shi)從芯(xin)(xin)棒運動(dong)受控(kong)這一(yi)特點出發的，故稱(cheng)(cheng)為“限動(dong)芯(xin)(xin)棒連軋(ya)(ya)(ya)管工藝”，后者是(shi)從Calmes 取名的“Multi-stand pilger mill”中“Pilger”變(bian)(bian)以“Pipe”演變(bian)(bian)而來的。由(you)于這一(yi)歷史(shi)原因，這種(zhong)軋(ya)(ya)(ya)機簡稱(cheng)(cheng)為 MPM軋(ya)(ya)(ya)機，而不(bu)是(shi)RMM.
采用這種工藝軋管，連軋不銹(xiu)鋼(gang)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工藝設備特征
a. MPM軋機的(de)特征
MPM軋(ya)機采用(yong)機械限(xian)動(dong)(dong)(dong)(dong)(dong)(dong)式芯(xin)(xin)(xin)棒(bang)速(su)(su)(su)度控制(zhi)裝置，芯(xin)(xin)(xin)棒(bang)的(de)快(kuai)速(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)(dong)作(zuo)（穿心(xin)棒(bang)、抽芯(xin)(xin)(xin)棒(bang)）及限(xian)動(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)作(zuo)（軋(ya)制(zhi)時控制(zhi)芯(xin)(xin)(xin)棒(bang)速(su)(su)(su)度）靠(kao)36m長的(de)大齒(chi)(chi)(chi)(chi)條(tiao)(tiao)來(lai)實現。快(kuai)速(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)(dong)作(zuo)由兩臺500kW直流電(dian)機分(fen)別(bie)驅動(dong)(dong)(dong)(dong)(dong)(dong)兩個(ge)齒(chi)(chi)(chi)(chi)輪，從(cong)齒(chi)(chi)(chi)(chi)條(tiao)(tiao)的(de)上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)。限(xian)動(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)作(zuo)時，由8個(ge)齒(chi)(chi)(chi)(chi)輪（上(shang)下(xia)各(ge)4個(ge)）從(cong)齒(chi)(chi)(chi)(chi)條(tiao)(tiao)的(de)上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)，每個(ge)齒(chi)(chi)(chi)(chi)輪均由1臺110kW直流電(dian)機單獨傳(chuan)動(dong)(dong)(dong)(dong)(dong)(dong)。芯(xin)(xin)(xin)棒(bang)運動(dong)(dong)(dong)(dong)(dong)(dong)方式的(de)改變依靠(kao)氣動(dong)(dong)(dong)(dong)(dong)(dong)離合器分(fen)別(bie)接(jie)通或脫(tuo)開相應的(de)齒(chi)(chi)(chi)(chi)輪來(lai)實現。芯(xin)(xin)(xin)棒(bang)的(de)快(kuai)速(su)(su)(su)行程(cheng)速(su)(su)(su)度為6m/s,限(xian)動(dong)(dong)(dong)(dong)(dong)(dong)速(su)(su)(su)度為0.2~0.5m/s,限(xian)動(dong)(dong)(dong)(dong)(dong)(dong)工作(zuo)行程(cheng)為5.0~5.2m.
在Dalmine公(gong)司進行試驗時，芯(xin)棒的運動速(su)度采用液(ye)壓控(kong)制。但(dan)因液(ye)壓系統控(kong)制芯(xin)棒速(su)度不夠穩定，有芯(xin)棒斷續(xu)運動的情況(kuang)，隨后(hou)改為齒輪齒條傳動的機械系統。
MPM的(de)軋輥孔(kong)型(xing)采用(yong)比普通連軋機(ji)開(kai)口(kou)角稍小的(de)封閉式圓孔(kong)（帶弧(hu)形(xing)開(kai)口(kou)），可以采用(yong)較大的(de)伸長率。
b. 脫管機的特征(zheng)
MPM的(de)(de)(de)(de)脫(tuo)管(guan)(guan)機(ji)(ji)(ji)與(yu)(yu)(yu)二輥(gun)式定(ding)徑機(ji)(ji)(ji)相同(tong)，由于(yu)MPM主軋(ya)(ya)(ya)(ya)機(ji)(ji)(ji)的(de)(de)(de)(de)第(di)(di)七(qi)、八(ba)機(ji)(ji)(ji)架(jia)的(de)(de)(de)(de)壓下量很小，僅靠第(di)(di)七(qi)、八(ba)機(ji)(ji)(ji)架(jia)軋(ya)(ya)(ya)(ya)輥(gun)的(de)(de)(de)(de)作用無法(fa)推送管(guan)(guan)子前進和使管(guan)(guan)子從芯棒前端脫(tuo)出，故在MPM工藝中(zhong)設置幾架(jia)脫(tuo)管(guan)(guan)機(ji)(ji)(ji)，起(qi)脫(tuo)管(guan)(guan)和定(ding)徑的(de)(de)(de)(de)作用。脫(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)直徑為(wei)720~850mm,輥(gun)身(shen)長(chang)420mm,第(di)(di)一、三架(jia)由1臺(tai)450kW的(de)(de)(de)(de)直流(liu)電機(ji)(ji)(ji)驅動(dong)(dong)，而第(di)(di)二架(jia)則(ze)(ze)單獨由1臺(tai)同(tong)型號電機(ji)(ji)(ji)驅動(dong)(dong)。脫(tuo)管(guan)(guan)速度必(bi)須按(an)連軋(ya)(ya)(ya)(ya)原則(ze)(ze)確定(ding)，并與(yu)(yu)(yu)MPM軋(ya)(ya)(ya)(ya)機(ji)(ji)(ji)的(de)(de)(de)(de)第(di)(di)八(ba)機(ji)(ji)(ji)架(jia)保(bao)持電氣連鎖(suo)。脫(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)(de)(de)(de)減(jian)徑率為(wei)3.5%~4.6%,孔(kong)型與(yu)(yu)(yu)一般二輥(gun)式定(ding)徑直機(ji)(ji)(ji)相同(tong)。
c. MPM工藝的芯棒(bang)運動特征
軋(ya)制(zhi)(zhi)過程中，要(yao)控制(zhi)(zhi)芯(xin)棒(bang)的速(su)度(du)，使其(qi)處于恒(heng)定狀態。雖然芯(xin)棒(bang)也隨(sui)管(guan)子前進，但(dan)其(qi)前進速(su)度(du)應遠(yuan)小于管(guan)子的速(su)度(du)，軋(ya)制(zhi)(zhi)結束后被抽出返回。軋(ya)制(zhi)(zhi)28m長的管(guan)子時(shi)，芯(xin)棒(bang)長度(du)為12m.芯(xin)棒(bang)為中空水(shui)冷(leng)芯(xin)棒(bang)，軋(ya)制(zhi)(zhi)結束后，芯(xin)棒(bang)溫度(du)為400℃,需要(yao)采用內外噴水(shui)使之(zhi)均勻冷(leng)卻。
2. 限動(dong)芯棒連軋管(guan)工藝技術發展的4個階段
不銹(xiu)鋼管(guan)(guan)(guan)限動芯棒連(lian)軋(ya)管(guan)(guan)(guan)工藝的(de)技(ji)術(shu)發展史應溯自1890年(nian)，Pfeiffer在一篇(pian)文(wen)章中寫道：“1890年(nian)發明家(jia)Heckert 申請(qing)了(le)(le)連(lian)軋(ya)技(ji)術(shu)專(zhuan)利，該技(ji)術(shu)采用十(shi)架(jia)兩輥高速軋(ya)機(ji)(ji)(ji)固定芯棒軋(ya)制空心管(guan)(guan)(guan)坯。可見在Calmes 多機(ji)(ji)(ji)架(jia)軋(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)問(wen)世前80年(nian)，就已有了(le)(le)雛形。”1968年(nian)A.H.Calmes 取得了(le)(le)MPM連(lian)軋(ya)管(guan)(guan)(guan)工藝的(de)權利，10年(nian)后(hou)，第一套MPM連(lian)軋(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)在Dalmine Bergamo 鋼管(guan)(guan)(guan)廠(chang)投產，到2003年(nian)12月天(tian)津無縫(feng)不銹(xiu)鋼管(guan)(guan)(guan)廠(chang)三輥式限動芯棒連(lian)軋(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)投產，已經(jing)歷了(le)(le)整(zheng)整(zheng)25年(nian)的(de)時間，和全浮動芯棒連(lian)軋(ya)管(guan)(guan)(guan)技(ji)術(shu)的(de)發展相(xiang)比，這(zhe)種工藝技(ji)術(shu)的(de)發展顯得快多了(le)(le)。這(zhe)25年(nian)的(de)發展歷程可劃分為四個階段，如表22-3所示(shi)。
