限動(dong)(dong)芯棒(bang)(bang)連(lian)軋(ya)管工藝被稱作(zuo)“Retained mandrel mill”或“Multi-stand pipe mill”（簡(jian)稱MPM),前者是(shi)從芯棒(bang)(bang)運動(dong)(dong)受控這一特點(dian)出發的，故稱為(wei)“限動(dong)(dong)芯棒(bang)(bang)連(lian)軋(ya)管工藝”，后者是(shi)從Calmes 取名(ming)的“Multi-stand pilger mill”中“Pilger”變以“Pipe”演變而來的。由于(yu)這一歷史原因，這種軋(ya)機簡(jian)稱為(wei) MPM軋(ya)機，而不是(shi)RMM.
采用這種工藝軋管，連軋不(bu)銹鋼(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(bei)特征
a. MPM軋機的特征
MPM軋機采(cai)用機械限動(dong)(dong)(dong)(dong)(dong)(dong)式芯(xin)棒(bang)速(su)(su)度控(kong)制(zhi)(zhi)裝置，芯(xin)棒(bang)的快速(su)(su)動(dong)(dong)(dong)(dong)(dong)(dong)作（穿心棒(bang)、抽芯(xin)棒(bang)）及限動(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)作（軋制(zhi)(zhi)時控(kong)制(zhi)(zhi)芯(xin)棒(bang)速(su)(su)度）靠(kao)36m長的大齒(chi)(chi)條(tiao)(tiao)來(lai)實現。快速(su)(su)動(dong)(dong)(dong)(dong)(dong)(dong)作由(you)兩臺500kW直流電(dian)機分別(bie)驅動(dong)(dong)(dong)(dong)(dong)(dong)兩個(ge)齒(chi)(chi)輪，從齒(chi)(chi)條(tiao)(tiao)的上下(xia)側(ce)帶動(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)作時，由(you)8個(ge)齒(chi)(chi)輪（上下(xia)各4個(ge)）從齒(chi)(chi)條(tiao)(tiao)的上下(xia)側(ce)帶動(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)條(tiao)(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)，每(mei)個(ge)齒(chi)(chi)輪均由(you)1臺110kW直流電(dian)機單獨傳動(dong)(dong)(dong)(dong)(dong)(dong)。芯(xin)棒(bang)運動(dong)(dong)(dong)(dong)(dong)(dong)方(fang)式的改變依靠(kao)氣動(dong)(dong)(dong)(dong)(dong)(dong)離合器分別(bie)接通或脫開相(xiang)應的齒(chi)(chi)輪來(lai)實現。芯(xin)棒(bang)的快速(su)(su)行程速(su)(su)度為(wei)6m/s,限動(dong)(dong)(dong)(dong)(dong)(dong)速(su)(su)度為(wei)0.2~0.5m/s,限動(dong)(dong)(dong)(dong)(dong)(dong)工作行程為(wei)5.0~5.2m.
在Dalmine公司(si)進行試驗時，芯棒(bang)的運動速度采用液(ye)壓(ya)(ya)控(kong)制。但因(yin)液(ye)壓(ya)(ya)系統控(kong)制芯棒(bang)速度不夠穩定，有(you)芯棒(bang)斷續運動的情況，隨后改為(wei)齒(chi)輪(lun)齒(chi)條傳(chuan)動的機械系統。
MPM的軋輥孔(kong)型采(cai)用(yong)比普通連軋機(ji)開(kai)口(kou)角稍(shao)小的封閉式圓孔(kong)（帶弧形開(kai)口(kou)），可以采(cai)用(yong)較大的伸長率。
b. 脫管機的特征
MPM的脫管機(ji)(ji)(ji)(ji)與(yu)(yu)二(er)輥式定徑(jing)(jing)機(ji)(ji)(ji)(ji)相同(tong)(tong)(tong)，由(you)于MPM主軋機(ji)(ji)(ji)(ji)的第(di)七(qi)、八(ba)機(ji)(ji)(ji)(ji)架的壓下(xia)量很小，僅靠第(di)七(qi)、八(ba)機(ji)(ji)(ji)(ji)架軋輥的作用(yong)無(wu)法推(tui)送(song)管子前(qian)進和(he)(he)使管子從(cong)芯棒前(qian)端脫出，故在MPM工藝中設置幾架脫管機(ji)(ji)(ji)(ji)，起脫管和(he)(he)定徑(jing)(jing)的作用(yong)。脫管機(ji)(ji)(ji)(ji)的軋輥直(zhi)徑(jing)(jing)為(wei)720~850mm,輥身長420mm,第(di)一(yi)、三架由(you)1臺(tai)450kW的直(zhi)流電(dian)機(ji)(ji)(ji)(ji)驅動，而第(di)二(er)架則單獨由(you)1臺(tai)同(tong)(tong)(tong)型號電(dian)機(ji)(ji)(ji)(ji)驅動。脫管速度必須按連軋原(yuan)則確(que)定，并與(yu)(yu)MPM軋機(ji)(ji)(ji)(ji)的第(di)八(ba)機(ji)(ji)(ji)(ji)架保持電(dian)氣連鎖。脫管機(ji)(ji)(ji)(ji)的減徑(jing)(jing)率為(wei)3.5%~4.6%,孔型與(yu)(yu)一(yi)般二(er)輥式定徑(jing)(jing)直(zhi)機(ji)(ji)(ji)(ji)相同(tong)(tong)(tong)。
c. MPM工(gong)藝的芯棒運動特征
軋制(zhi)(zhi)過程中，要(yao)控制(zhi)(zhi)芯(xin)棒的(de)速度，使其處于(yu)恒定(ding)狀態(tai)。雖然(ran)芯(xin)棒也隨管子(zi)(zi)前進，但其前進速度應遠(yuan)小于(yu)管子(zi)(zi)的(de)速度，軋制(zhi)(zhi)結束后被抽出返回。軋制(zhi)(zhi)28m長(chang)的(de)管子(zi)(zi)時，芯(xin)棒長(chang)度為12m.芯(xin)棒為中空水冷(leng)(leng)芯(xin)棒，軋制(zhi)(zhi)結束后，芯(xin)棒溫度為400℃,需要(yao)采用內外噴水使之均勻冷(leng)(leng)卻。
2. 限動芯棒連軋管工藝(yi)技(ji)術發展的(de)4個階(jie)段
不銹(xiu)鋼(gang)管(guan)(guan)限動(dong)芯棒連(lian)(lian)軋(ya)(ya)管(guan)(guan)工(gong)藝(yi)的(de)技(ji)術發展(zhan)(zhan)史(shi)應溯自1890年(nian)，Pfeiffer在(zai)一篇(pian)文章(zhang)中寫道：“1890年(nian)發明家Heckert 申請了(le)(le)連(lian)(lian)軋(ya)(ya)技(ji)術專利(li)，該技(ji)術采用十(shi)架兩輥(gun)高速軋(ya)(ya)機(ji)固(gu)定(ding)芯棒軋(ya)(ya)制(zhi)空心管(guan)(guan)坯。可見(jian)在(zai)Calmes 多(duo)機(ji)架軋(ya)(ya)管(guan)(guan)機(ji)問世前(qian)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)(lian)軋(ya)(ya)管(guan)(guan)工(gong)藝(yi)的(de)權利(li)，10年(nian)后，第一套MPM連(lian)(lian)軋(ya)(ya)管(guan)(guan)機(ji)在(zai)Dalmine Bergamo 鋼(gang)管(guan)(guan)廠(chang)投產(chan)，到2003年(nian)12月(yue)天津無縫不銹(xiu)鋼(gang)管(guan)(guan)廠(chang)三(san)輥(gun)式限動(dong)芯棒連(lian)(lian)軋(ya)(ya)管(guan)(guan)機(ji)投產(chan)，已經歷了(le)(le)整(zheng)整(zheng)25年(nian)的(de)時間，和全(quan)浮(fu)動(dong)芯棒連(lian)(lian)軋(ya)(ya)管(guan)(guan)技(ji)術的(de)發展(zhan)(zhan)相比，這(zhe)種工(gong)藝(yi)技(ji)術的(de)發展(zhan)(zhan)顯(xian)得快(kuai)多(duo)了(le)(le)。這(zhe)25年(nian)的(de)發展(zhan)(zhan)歷程可劃分為四個階段，如表22-3所示。
