限(xian)動(dong)芯棒(bang)連軋(ya)(ya)管(guan)工(gong)藝(yi)被(bei)稱(cheng)(cheng)作“Retained mandrel mill”或“Multi-stand pipe mill”（簡稱(cheng)(cheng)MPM),前者是(shi)從芯棒(bang)運動(dong)受控(kong)這一特點出發的，故稱(cheng)(cheng)為“限(xian)動(dong)芯棒(bang)連軋(ya)(ya)管(guan)工(gong)藝(yi)”，后者是(shi)從Calmes 取名(ming)的“Multi-stand pilger mill”中(zhong)“Pilger”變以“Pipe”演(yan)變而(er)來的。由于這一歷史原因，這種軋(ya)(ya)機簡稱(cheng)(cheng)為 MPM軋(ya)(ya)機，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工藝設備特征(zheng)
a. MPM軋機(ji)的(de)特征
MPM軋(ya)機采用機械限動(dong)(dong)(dong)(dong)式芯(xin)(xin)棒(bang)(bang)(bang)速度(du)控制裝置，芯(xin)(xin)棒(bang)(bang)(bang)的快(kuai)速動(dong)(dong)(dong)(dong)作（穿心棒(bang)(bang)(bang)、抽芯(xin)(xin)棒(bang)(bang)(bang)）及限動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作（軋(ya)制時控制芯(xin)(xin)棒(bang)(bang)(bang)速度(du)）靠36m長(chang)的大齒條(tiao)(tiao)來(lai)實(shi)現。快(kuai)速動(dong)(dong)(dong)(dong)作由(you)兩(liang)臺500kW直流(liu)電機分別(bie)驅動(dong)(dong)(dong)(dong)兩(liang)個(ge)齒輪，從齒條(tiao)(tiao)的上下側帶動(dong)(dong)(dong)(dong)齒條(tiao)(tiao)運動(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作時，由(you)8個(ge)齒輪（上下各(ge)4個(ge)）從齒條(tiao)(tiao)的上下側帶動(dong)(dong)(dong)(dong)齒條(tiao)(tiao)運動(dong)(dong)(dong)(dong)，每(mei)個(ge)齒輪均由(you)1臺110kW直流(liu)電機單獨傳動(dong)(dong)(dong)(dong)。芯(xin)(xin)棒(bang)(bang)(bang)運動(dong)(dong)(dong)(dong)方式的改變依靠氣動(dong)(dong)(dong)(dong)離合器(qi)分別(bie)接通(tong)或脫開(kai)相應的齒輪來(lai)實(shi)現。芯(xin)(xin)棒(bang)(bang)(bang)的快(kuai)速行(xing)程(cheng)速度(du)為(wei)6m/s,限動(dong)(dong)(dong)(dong)速度(du)為(wei)0.2~0.5m/s,限動(dong)(dong)(dong)(dong)工(gong)作行(xing)程(cheng)為(wei)5.0~5.2m.
在Dalmine公(gong)司進行試(shi)驗時，芯棒(bang)的(de)運動速度采(cai)用(yong)液壓控(kong)制。但因液壓系(xi)統(tong)控(kong)制芯棒(bang)速度不夠穩定，有(you)芯棒(bang)斷(duan)續運動的(de)情況(kuang)，隨(sui)后改為齒輪齒條傳(chuan)動的(de)機械系(xi)統(tong)。
MPM的(de)軋(ya)輥孔(kong)型采用(yong)(yong)比(bi)普通(tong)連(lian)軋(ya)機開口(kou)角稍小的(de)封(feng)閉式圓孔(kong)（帶弧形開口(kou)），可以采用(yong)(yong)較大的(de)伸長率。
b. 脫管(guan)機的(de)特征
MPM的(de)脫(tuo)管(guan)(guan)機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)與二輥式定徑機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)相同(tong)(tong)，由(you)(you)于MPM主軋機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)的(de)第七、八機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)架(jia)的(de)壓下量很小(xiao)，僅靠第七、八機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)架(jia)軋輥的(de)作(zuo)用無(wu)法(fa)推送(song)管(guan)(guan)子前進和(he)(he)使管(guan)(guan)子從芯棒前端脫(tuo)出，故(gu)在(zai)MPM工藝中設置幾架(jia)脫(tuo)管(guan)(guan)機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)，起(qi)脫(tuo)管(guan)(guan)和(he)(he)定徑的(de)作(zuo)用。脫(tuo)管(guan)(guan)機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)的(de)軋輥直(zhi)徑為720~850mm,輥身長420mm,第一(yi)、三架(jia)由(you)(you)1臺450kW的(de)直(zhi)流電機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)驅動，而第二架(jia)則單獨(du)由(you)(you)1臺同(tong)(tong)型號(hao)電機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)驅動。脫(tuo)管(guan)(guan)速(su)度必須按連軋原(yuan)則確定，并與MPM軋機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)的(de)第八機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)架(jia)保持電氣連鎖。脫(tuo)管(guan)(guan)機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)的(de)減徑率為3.5%~4.6%,孔(kong)型與一(yi)般二輥式定徑直(zhi)機(ji)(ji)(ji)(ji)(ji)(ji)(ji)(ji)相同(tong)(tong)。
c. MPM工藝的(de)芯棒運動特征
軋(ya)制(zhi)過程中，要(yao)(yao)控(kong)制(zhi)芯(xin)棒的速度(du)，使其處于恒定狀態。雖然(ran)芯(xin)棒也隨(sui)管(guan)子前(qian)進(jin)，但其前(qian)進(jin)速度(du)應遠小于管(guan)子的速度(du)，軋(ya)制(zhi)結(jie)束后(hou)被抽出返(fan)回(hui)。軋(ya)制(zhi)28m長(chang)的管(guan)子時，芯(xin)棒長(chang)度(du)為(wei)12m.芯(xin)棒為(wei)中空水冷芯(xin)棒，軋(ya)制(zhi)結(jie)束后(hou)，芯(xin)棒溫度(du)為(wei)400℃,需要(yao)(yao)采用內外噴水使之均勻冷卻。
2. 限動(dong)芯棒連(lian)軋管工藝技(ji)術發展(zhan)的4個階段
不銹(xiu)鋼管(guan)(guan)(guan)限(xian)動(dong)芯(xin)(xin)棒(bang)連(lian)軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)工(gong)藝的(de)技術(shu)發(fa)(fa)展(zhan)(zhan)(zhan)史(shi)應溯自1890年(nian)(nian)(nian)，Pfeiffer在一篇文章(zhang)中寫道：“1890年(nian)(nian)(nian)發(fa)(fa)明(ming)家(jia)Heckert 申請(qing)了連(lian)軋(ya)(ya)(ya)(ya)技術(shu)專(zhuan)利(li)，該技術(shu)采(cai)用十架兩輥高速(su)軋(ya)(ya)(ya)(ya)機(ji)(ji)(ji)固(gu)定(ding)芯(xin)(xin)棒(bang)軋(ya)(ya)(ya)(ya)制空心管(guan)(guan)(guan)坯。可見(jian)在Calmes 多(duo)(duo)機(ji)(ji)(ji)架軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)問世前80年(nian)(nian)(nian)，就已(yi)有(you)了雛形(xing)。”1968年(nian)(nian)(nian)A.H.Calmes 取(qu)得(de)了MPM連(lian)軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)工(gong)藝的(de)權利(li)，10年(nian)(nian)(nian)后，第一套(tao)MPM連(lian)軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)在Dalmine Bergamo 鋼管(guan)(guan)(guan)廠(chang)投(tou)產(chan)，到2003年(nian)(nian)(nian)12月天(tian)津(jin)無縫不銹(xiu)鋼管(guan)(guan)(guan)廠(chang)三輥式限(xian)動(dong)芯(xin)(xin)棒(bang)連(lian)軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)機(ji)(ji)(ji)投(tou)產(chan)，已(yi)經歷(li)了整整25年(nian)(nian)(nian)的(de)時間，和全浮動(dong)芯(xin)(xin)棒(bang)連(lian)軋(ya)(ya)(ya)(ya)管(guan)(guan)(guan)技術(shu)的(de)發(fa)(fa)展(zhan)(zhan)(zhan)相(xiang)比(bi)，這(zhe)(zhe)種工(gong)藝技術(shu)的(de)發(fa)(fa)展(zhan)(zhan)(zhan)顯得(de)快(kuai)多(duo)(duo)了。這(zhe)(zhe)25年(nian)(nian)(nian)的(de)發(fa)(fa)展(zhan)(zhan)(zhan)歷(li)程可劃分為四個階段，如表22-3所示(shi)。
