限動(dong)(dong)芯棒連軋(ya)管工藝被(bei)稱(cheng)作“Retained mandrel mill”或“Multi-stand pipe mill”（簡稱(cheng)MPM),前者是從(cong)芯棒運動(dong)(dong)受控(kong)這(zhe)一特點出發的，故稱(cheng)為“限動(dong)(dong)芯棒連軋(ya)管工藝”，后者是從(cong)Calmes 取名的“Multi-stand pilger mill”中(zhong)“Pilger”變(bian)以“Pipe”演變(bian)而來的。由于這(zhe)一歷史原因，這(zhe)種(zhong)軋(ya)機(ji)簡稱(cheng)為 MPM軋(ya)機(ji)，而不是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
a. MPM軋(ya)機的特征
MPM軋機(ji)采用機(ji)械(xie)限動(dong)(dong)(dong)(dong)(dong)(dong)(dong)式芯(xin)(xin)棒(bang)(bang)速(su)度(du)控制裝置(zhi)，芯(xin)(xin)棒(bang)(bang)的(de)快速(su)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)作（穿心棒(bang)(bang)、抽芯(xin)(xin)棒(bang)(bang)）及限動(dong)(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)作（軋制時控制芯(xin)(xin)棒(bang)(bang)速(su)度(du)）靠36m長的(de)大齒(chi)條(tiao)來實現(xian)。快速(su)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)作由兩臺500kW直流(liu)電機(ji)分別驅動(dong)(dong)(dong)(dong)(dong)(dong)(dong)兩個齒(chi)輪(lun)(lun)，從(cong)齒(chi)條(tiao)的(de)上下側帶動(dong)(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)條(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)作時，由8個齒(chi)輪(lun)(lun)（上下各(ge)4個）從(cong)齒(chi)條(tiao)的(de)上下側帶動(dong)(dong)(dong)(dong)(dong)(dong)(dong)齒(chi)條(tiao)運動(dong)(dong)(dong)(dong)(dong)(dong)(dong)，每個齒(chi)輪(lun)(lun)均由1臺110kW直流(liu)電機(ji)單獨(du)傳(chuan)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)。芯(xin)(xin)棒(bang)(bang)運動(dong)(dong)(dong)(dong)(dong)(dong)(dong)方式的(de)改(gai)變(bian)依靠氣(qi)動(dong)(dong)(dong)(dong)(dong)(dong)(dong)離合器(qi)分別接通(tong)或脫(tuo)開相應的(de)齒(chi)輪(lun)(lun)來實現(xian)。芯(xin)(xin)棒(bang)(bang)的(de)快速(su)行程速(su)度(du)為(wei)6m/s,限動(dong)(dong)(dong)(dong)(dong)(dong)(dong)速(su)度(du)為(wei)0.2~0.5m/s,限動(dong)(dong)(dong)(dong)(dong)(dong)(dong)工作行程為(wei)5.0~5.2m.
在Dalmine公司進行(xing)試驗時，芯(xin)棒的(de)運動(dong)速度采用液壓控(kong)(kong)制。但因液壓系統控(kong)(kong)制芯(xin)棒速度不夠穩定(ding)，有芯(xin)棒斷續運動(dong)的(de)情況(kuang)，隨后改為齒輪齒條(tiao)傳動(dong)的(de)機械系統。
MPM的軋(ya)輥孔(kong)型(xing)采用比普通連軋(ya)機開(kai)口(kou)角稍小的封閉(bi)式圓孔(kong)（帶弧形開(kai)口(kou)），可(ke)以(yi)采用較大的伸(shen)長(chang)率。
b. 脫管(guan)機的特征
MPM的脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)與二(er)輥式定徑機(ji)(ji)(ji)相同，由(you)于MPM主軋(ya)機(ji)(ji)(ji)的第七、八(ba)機(ji)(ji)(ji)架的壓下量很(hen)小，僅靠第七、八(ba)機(ji)(ji)(ji)架軋(ya)輥的作用(yong)無法(fa)推送管(guan)子前進和使(shi)管(guan)子從芯棒前端脫(tuo)(tuo)出，故在MPM工藝(yi)中設置幾架脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)，起脫(tuo)(tuo)管(guan)和定徑的作用(yong)。脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)的軋(ya)輥直(zhi)(zhi)徑為720~850mm,輥身長420mm,第一、三(san)架由(you)1臺450kW的直(zhi)(zhi)流電機(ji)(ji)(ji)驅動(dong)，而第二(er)架則單獨由(you)1臺同型(xing)號電機(ji)(ji)(ji)驅動(dong)。脫(tuo)(tuo)管(guan)速度(du)必(bi)須(xu)按(an)連軋(ya)原則確定，并與MPM軋(ya)機(ji)(ji)(ji)的第八(ba)機(ji)(ji)(ji)架保(bao)持電氣連鎖(suo)。脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)的減徑率(lv)為3.5%~4.6%,孔型(xing)與一般二(er)輥式定徑直(zhi)(zhi)機(ji)(ji)(ji)相同。
c. MPM工藝的芯棒運動特征
軋(ya)制(zhi)過(guo)程中，要控制(zhi)芯棒的(de)速度(du)，使其處于恒定狀態。雖然芯棒也(ye)隨管子前(qian)進，但其前(qian)進速度(du)應遠小于管子的(de)速度(du)，軋(ya)制(zhi)結(jie)(jie)束后被抽出返回。軋(ya)制(zhi)28m長(chang)(chang)的(de)管子時，芯棒長(chang)(chang)度(du)為12m.芯棒為中空水冷(leng)芯棒，軋(ya)制(zhi)結(jie)(jie)束后，芯棒溫度(du)為400℃,需要采用(yong)內外噴水使之均勻(yun)冷(leng)卻。
2. 限動芯(xin)棒連軋(ya)管工藝技術發(fa)展的(de)4個階段
不(bu)銹(xiu)(xiu)鋼管(guan)(guan)(guan)限動芯(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)工(gong)藝的(de)技(ji)術(shu)發展(zhan)史應溯自(zi)1890年(nian)，Pfeiffer在(zai)(zai)一篇文(wen)章中寫道：“1890年(nian)發明(ming)家(jia)Heckert 申(shen)請了連(lian)軋(ya)(ya)技(ji)術(shu)專利(li)，該技(ji)術(shu)采用十架兩輥(gun)高速軋(ya)(ya)機(ji)(ji)固定芯(xin)棒軋(ya)(ya)制空心(xin)管(guan)(guan)(guan)坯。可見在(zai)(zai)Calmes 多機(ji)(ji)架軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)問世(shi)前80年(nian)，就已有了雛形。”1968年(nian)A.H.Calmes 取得(de)了MPM連(lian)軋(ya)(ya)管(guan)(guan)(guan)工(gong)藝的(de)權(quan)利(li)，10年(nian)后，第一套MPM連(lian)軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)在(zai)(zai)Dalmine Bergamo 鋼管(guan)(guan)(guan)廠投(tou)(tou)產(chan)，到2003年(nian)12月天津無縫不(bu)銹(xiu)(xiu)鋼管(guan)(guan)(guan)廠三輥(gun)式限動芯(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)投(tou)(tou)產(chan)，已經歷了整整25年(nian)的(de)時間，和全(quan)浮(fu)動芯(xin)棒連(lian)軋(ya)(ya)管(guan)(guan)(guan)技(ji)術(shu)的(de)發展(zhan)相比，這種工(gong)藝技(ji)術(shu)的(de)發展(zhan)顯得(de)快多了。這25年(nian)的(de)發展(zhan)歷程(cheng)可劃(hua)分(fen)為四個(ge)階段，如表22-3所示(shi)。
