限(xian)動(dong)芯棒(bang)連軋管(guan)工藝被稱作(zuo)“Retained mandrel mill”或(huo)“Multi-stand pipe mill”（簡稱MPM),前(qian)者是(shi)從(cong)芯棒(bang)運動(dong)受控這(zhe)一特(te)點出發的(de)，故(gu)稱為“限(xian)動(dong)芯棒(bang)連軋管(guan)工藝”，后者是(shi)從(cong)Calmes 取名的(de)“Multi-stand pilger mill”中“Pilger”變(bian)以“Pipe”演(yan)變(bian)而來的(de)。由于這(zhe)一歷(li)史原(yuan)因(yin)，這(zhe)種軋機(ji)簡稱為 MPM軋機(ji)，而不是(shi)RMM.
采用這種工藝軋管，連軋不銹(xiu)鋼管(guan)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(she)備特征
a. MPM軋(ya)機的(de)特征
MPM軋(ya)機采(cai)用機械限動(dong)(dong)(dong)(dong)式芯(xin)棒(bang)(bang)(bang)(bang)速度控制裝置，芯(xin)棒(bang)(bang)(bang)(bang)的快速動(dong)(dong)(dong)(dong)作(zuo)(zuo)（穿心棒(bang)(bang)(bang)(bang)、抽(chou)芯(xin)棒(bang)(bang)(bang)(bang)）及限動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作(zuo)(zuo)（軋(ya)制時(shi)控制芯(xin)棒(bang)(bang)(bang)(bang)速度）靠(kao)(kao)36m長(chang)的大齒(chi)(chi)(chi)條(tiao)(tiao)來(lai)實現(xian)。快速動(dong)(dong)(dong)(dong)作(zuo)(zuo)由(you)兩(liang)臺500kW直流(liu)電(dian)機分(fen)別驅動(dong)(dong)(dong)(dong)兩(liang)個(ge)齒(chi)(chi)(chi)輪(lun)(lun)，從(cong)齒(chi)(chi)(chi)條(tiao)(tiao)的上(shang)下(xia)(xia)側帶動(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)條(tiao)(tiao)運(yun)(yun)動(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作(zuo)(zuo)時(shi)，由(you)8個(ge)齒(chi)(chi)(chi)輪(lun)(lun)（上(shang)下(xia)(xia)各4個(ge)）從(cong)齒(chi)(chi)(chi)條(tiao)(tiao)的上(shang)下(xia)(xia)側帶動(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)條(tiao)(tiao)運(yun)(yun)動(dong)(dong)(dong)(dong)，每(mei)個(ge)齒(chi)(chi)(chi)輪(lun)(lun)均由(you)1臺110kW直流(liu)電(dian)機單獨傳(chuan)動(dong)(dong)(dong)(dong)。芯(xin)棒(bang)(bang)(bang)(bang)運(yun)(yun)動(dong)(dong)(dong)(dong)方式的改變(bian)依靠(kao)(kao)氣動(dong)(dong)(dong)(dong)離合器分(fen)別接通或脫開相應的齒(chi)(chi)(chi)輪(lun)(lun)來(lai)實現(xian)。芯(xin)棒(bang)(bang)(bang)(bang)的快速行(xing)程速度為6m/s,限動(dong)(dong)(dong)(dong)速度為0.2~0.5m/s,限動(dong)(dong)(dong)(dong)工作(zuo)(zuo)行(xing)程為5.0~5.2m.
在Dalmine公司進行試驗時，芯棒的運動(dong)速度采用液(ye)壓控(kong)制。但因(yin)液(ye)壓系統控(kong)制芯棒速度不(bu)夠穩定，有芯棒斷(duan)續(xu)運動(dong)的情況，隨后改為齒輪齒條傳動(dong)的機械系統。
MPM的(de)軋輥孔型采用(yong)(yong)比普通連軋機開口(kou)(kou)角(jiao)稍小的(de)封(feng)閉式圓孔（帶弧形開口(kou)(kou)），可(ke)以(yi)采用(yong)(yong)較大的(de)伸長(chang)率。
b. 脫管機的(de)特(te)征
MPM的(de)(de)(de)(de)脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)與二輥(gun)式定(ding)徑(jing)(jing)(jing)機(ji)(ji)相同(tong)，由于MPM主軋(ya)(ya)(ya)機(ji)(ji)的(de)(de)(de)(de)第(di)七、八機(ji)(ji)架(jia)的(de)(de)(de)(de)壓(ya)下量很小，僅靠第(di)七、八機(ji)(ji)架(jia)軋(ya)(ya)(ya)輥(gun)的(de)(de)(de)(de)作(zuo)用(yong)無法推(tui)送(song)管(guan)(guan)子前進和(he)(he)使管(guan)(guan)子從芯棒前端脫(tuo)(tuo)(tuo)出(chu)，故在MPM工藝中設(she)置幾架(jia)脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)，起脫(tuo)(tuo)(tuo)管(guan)(guan)和(he)(he)定(ding)徑(jing)(jing)(jing)的(de)(de)(de)(de)作(zuo)用(yong)。脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)的(de)(de)(de)(de)軋(ya)(ya)(ya)輥(gun)直(zhi)徑(jing)(jing)(jing)為720~850mm,輥(gun)身長420mm,第(di)一(yi)(yi)、三架(jia)由1臺450kW的(de)(de)(de)(de)直(zhi)流電機(ji)(ji)驅(qu)動，而第(di)二架(jia)則單獨由1臺同(tong)型號(hao)電機(ji)(ji)驅(qu)動。脫(tuo)(tuo)(tuo)管(guan)(guan)速(su)度必(bi)須按連(lian)(lian)軋(ya)(ya)(ya)原則確定(ding)，并與MPM軋(ya)(ya)(ya)機(ji)(ji)的(de)(de)(de)(de)第(di)八機(ji)(ji)架(jia)保持電氣連(lian)(lian)鎖。脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)的(de)(de)(de)(de)減徑(jing)(jing)(jing)率為3.5%~4.6%,孔型與一(yi)(yi)般二輥(gun)式定(ding)徑(jing)(jing)(jing)直(zhi)機(ji)(ji)相同(tong)。
c. MPM工(gong)藝(yi)的芯棒運動特征
軋(ya)(ya)制過程(cheng)中，要控制芯(xin)棒(bang)的速度(du)(du)，使其處于(yu)(yu)恒定(ding)狀態。雖然芯(xin)棒(bang)也隨管(guan)(guan)子前(qian)進，但其前(qian)進速度(du)(du)應遠小(xiao)于(yu)(yu)管(guan)(guan)子的速度(du)(du)，軋(ya)(ya)制結束(shu)后被抽出(chu)返回。軋(ya)(ya)制28m長的管(guan)(guan)子時，芯(xin)棒(bang)長度(du)(du)為(wei)12m.芯(xin)棒(bang)為(wei)中空水(shui)(shui)冷(leng)芯(xin)棒(bang)，軋(ya)(ya)制結束(shu)后，芯(xin)棒(bang)溫度(du)(du)為(wei)400℃,需要采用內外(wai)噴水(shui)(shui)使之均勻冷(leng)卻。
2. 限動(dong)芯棒連軋管工藝(yi)技術發展的4個階段(duan)
不銹鋼(gang)(gang)管(guan)(guan)限動芯(xin)(xin)棒(bang)(bang)連軋管(guan)(guan)工藝(yi)的(de)(de)技術(shu)發展史應溯自1890年(nian)，Pfeiffer在(zai)一篇文章(zhang)中寫道：“1890年(nian)發明家Heckert 申請了連軋技術(shu)專利，該技術(shu)采用十(shi)架兩輥高(gao)速軋機(ji)(ji)(ji)固(gu)定芯(xin)(xin)棒(bang)(bang)軋制(zhi)空心管(guan)(guan)坯。可見在(zai)Calmes 多(duo)機(ji)(ji)(ji)架軋管(guan)(guan)機(ji)(ji)(ji)問世前80年(nian)，就(jiu)已有了雛形(xing)。”1968年(nian)A.H.Calmes 取得了MPM連軋管(guan)(guan)工藝(yi)的(de)(de)權(quan)利，10年(nian)后(hou)，第(di)一套(tao)MPM連軋管(guan)(guan)機(ji)(ji)(ji)在(zai)Dalmine Bergamo 鋼(gang)(gang)管(guan)(guan)廠投產，到2003年(nian)12月天津無(wu)縫不銹鋼(gang)(gang)管(guan)(guan)廠三(san)輥式限動芯(xin)(xin)棒(bang)(bang)連軋管(guan)(guan)機(ji)(ji)(ji)投產，已經歷了整整25年(nian)的(de)(de)時間，和(he)全浮(fu)動芯(xin)(xin)棒(bang)(bang)連軋管(guan)(guan)技術(shu)的(de)(de)發展相比，這種工藝(yi)技術(shu)的(de)(de)發展顯得快多(duo)了。這25年(nian)的(de)(de)發展歷程(cheng)可劃(hua)分為四個階段，如表22-3所(suo)示。
