限動(dong)芯棒連(lian)軋管(guan)工(gong)藝被稱(cheng)作“Retained mandrel mill”或“Multi-stand pipe mill”（簡(jian)(jian)稱(cheng)MPM),前者是從芯棒運(yun)動(dong)受(shou)控這一特點出發的(de)，故稱(cheng)為“限動(dong)芯棒連(lian)軋管(guan)工(gong)藝”，后者是從Calmes 取(qu)名的(de)“Multi-stand pilger mill”中(zhong)“Pilger”變(bian)以“Pipe”演變(bian)而來的(de)。由于(yu)這一歷史原因，這種(zhong)軋機簡(jian)(jian)稱(cheng)為 MPM軋機，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(gong)藝設備(bei)特征
a. MPM軋機的特征
MPM軋機(ji)(ji)采用機(ji)(ji)械限(xian)動(dong)(dong)(dong)(dong)式芯(xin)(xin)棒(bang)(bang)(bang)速(su)(su)度控制裝置(zhi)，芯(xin)(xin)棒(bang)(bang)(bang)的快(kuai)速(su)(su)動(dong)(dong)(dong)(dong)作(zuo)（穿心棒(bang)(bang)(bang)、抽(chou)芯(xin)(xin)棒(bang)(bang)(bang)）及限(xian)動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作(zuo)（軋制時(shi)(shi)控制芯(xin)(xin)棒(bang)(bang)(bang)速(su)(su)度）靠(kao)(kao)36m長的大齒(chi)(chi)條(tiao)來實現。快(kuai)速(su)(su)動(dong)(dong)(dong)(dong)作(zuo)由(you)兩臺(tai)500kW直流電(dian)機(ji)(ji)分別驅動(dong)(dong)(dong)(dong)兩個(ge)(ge)(ge)齒(chi)(chi)輪(lun)，從(cong)齒(chi)(chi)條(tiao)的上下側(ce)帶動(dong)(dong)(dong)(dong)齒(chi)(chi)條(tiao)運(yun)(yun)動(dong)(dong)(dong)(dong)。限(xian)動(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)作(zuo)時(shi)(shi)，由(you)8個(ge)(ge)(ge)齒(chi)(chi)輪(lun)（上下各4個(ge)(ge)(ge)）從(cong)齒(chi)(chi)條(tiao)的上下側(ce)帶動(dong)(dong)(dong)(dong)齒(chi)(chi)條(tiao)運(yun)(yun)動(dong)(dong)(dong)(dong)，每(mei)個(ge)(ge)(ge)齒(chi)(chi)輪(lun)均由(you)1臺(tai)110kW直流電(dian)機(ji)(ji)單獨(du)傳動(dong)(dong)(dong)(dong)。芯(xin)(xin)棒(bang)(bang)(bang)運(yun)(yun)動(dong)(dong)(dong)(dong)方式的改變依靠(kao)(kao)氣動(dong)(dong)(dong)(dong)離合器分別接通或脫開相應(ying)的齒(chi)(chi)輪(lun)來實現。芯(xin)(xin)棒(bang)(bang)(bang)的快(kuai)速(su)(su)行程(cheng)速(su)(su)度為(wei)6m/s,限(xian)動(dong)(dong)(dong)(dong)速(su)(su)度為(wei)0.2~0.5m/s,限(xian)動(dong)(dong)(dong)(dong)工作(zuo)行程(cheng)為(wei)5.0~5.2m.
在Dalmine公司進行試驗時，芯棒的運動速度(du)采(cai)用液壓控制。但因液壓系(xi)統控制芯棒速度(du)不(bu)夠穩(wen)定，有(you)芯棒斷續(xu)運動的情況，隨(sui)后改為齒(chi)輪齒(chi)條傳動的機(ji)械系(xi)統。
MPM的(de)軋輥(gun)孔(kong)型采用比普(pu)通連軋機開口角稍小的(de)封閉式圓孔(kong)（帶弧(hu)形開口），可(ke)以(yi)采用較大的(de)伸長率。
b. 脫管機(ji)的特(te)征
MPM的(de)(de)(de)脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)與二(er)輥(gun)式定(ding)徑(jing)機(ji)(ji)(ji)相(xiang)同(tong)，由于(yu)MPM主軋(ya)機(ji)(ji)(ji)的(de)(de)(de)第(di)(di)七、八機(ji)(ji)(ji)架(jia)(jia)的(de)(de)(de)壓下量很小，僅靠第(di)(di)七、八機(ji)(ji)(ji)架(jia)(jia)軋(ya)輥(gun)的(de)(de)(de)作用(yong)無法推送管(guan)子前進和(he)(he)使管(guan)子從芯(xin)棒前端(duan)脫(tuo)(tuo)出，故在MPM工藝中設置幾架(jia)(jia)脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)，起脫(tuo)(tuo)管(guan)和(he)(he)定(ding)徑(jing)的(de)(de)(de)作用(yong)。脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)的(de)(de)(de)軋(ya)輥(gun)直(zhi)徑(jing)為720~850mm,輥(gun)身長420mm,第(di)(di)一、三架(jia)(jia)由1臺(tai)450kW的(de)(de)(de)直(zhi)流(liu)電(dian)機(ji)(ji)(ji)驅(qu)動，而(er)第(di)(di)二(er)架(jia)(jia)則單獨(du)由1臺(tai)同(tong)型號(hao)電(dian)機(ji)(ji)(ji)驅(qu)動。脫(tuo)(tuo)管(guan)速(su)度必(bi)須按連軋(ya)原則確(que)定(ding)，并與MPM軋(ya)機(ji)(ji)(ji)的(de)(de)(de)第(di)(di)八機(ji)(ji)(ji)架(jia)(jia)保(bao)持電(dian)氣連鎖(suo)。脫(tuo)(tuo)管(guan)機(ji)(ji)(ji)的(de)(de)(de)減(jian)徑(jing)率為3.5%~4.6%,孔型與一般二(er)輥(gun)式定(ding)徑(jing)直(zhi)機(ji)(ji)(ji)相(xiang)同(tong)。
c. MPM工(gong)藝的芯棒運(yun)動特征(zheng)
軋制(zhi)(zhi)(zhi)過程(cheng)中，要控(kong)制(zhi)(zhi)(zhi)芯(xin)棒(bang)(bang)的(de)速(su)(su)度(du)(du)(du)，使其(qi)處于恒定(ding)狀態。雖然芯(xin)棒(bang)(bang)也隨管子(zi)前(qian)進，但其(qi)前(qian)進速(su)(su)度(du)(du)(du)應(ying)遠小于管子(zi)的(de)速(su)(su)度(du)(du)(du)，軋制(zhi)(zhi)(zhi)結束后(hou)(hou)被抽出返回。軋制(zhi)(zhi)(zhi)28m長的(de)管子(zi)時，芯(xin)棒(bang)(bang)長度(du)(du)(du)為(wei)12m.芯(xin)棒(bang)(bang)為(wei)中空水冷芯(xin)棒(bang)(bang)，軋制(zhi)(zhi)(zhi)結束后(hou)(hou)，芯(xin)棒(bang)(bang)溫(wen)度(du)(du)(du)為(wei)400℃,需要采用內外噴水使之均勻(yun)冷卻(que)。
2. 限動芯(xin)棒(bang)連(lian)軋管(guan)工藝(yi)技術發(fa)展的4個階段
不(bu)銹(xiu)鋼管(guan)限(xian)動芯棒(bang)連軋(ya)(ya)管(guan)工(gong)藝的技術發(fa)展(zhan)(zhan)史應溯自(zi)1890年(nian)(nian)，Pfeiffer在一篇(pian)文章中寫道：“1890年(nian)(nian)發(fa)明家Heckert 申(shen)請了(le)連軋(ya)(ya)技術專利，該技術采(cai)用十架(jia)兩輥高速軋(ya)(ya)機(ji)(ji)固定芯棒(bang)軋(ya)(ya)制(zhi)空心管(guan)坯(pi)。可見在Calmes 多(duo)機(ji)(ji)架(jia)軋(ya)(ya)管(guan)機(ji)(ji)問世前80年(nian)(nian)，就已有了(le)雛形(xing)。”1968年(nian)(nian)A.H.Calmes 取得(de)了(le)MPM連軋(ya)(ya)管(guan)工(gong)藝的權利，10年(nian)(nian)后，第一套MPM連軋(ya)(ya)管(guan)機(ji)(ji)在Dalmine Bergamo 鋼管(guan)廠投產，到2003年(nian)(nian)12月天(tian)津(jin)無縫不(bu)銹(xiu)鋼管(guan)廠三(san)輥式限(xian)動芯棒(bang)連軋(ya)(ya)管(guan)機(ji)(ji)投產，已經歷(li)(li)了(le)整(zheng)整(zheng)25年(nian)(nian)的時間，和全浮動芯棒(bang)連軋(ya)(ya)管(guan)技術的發(fa)展(zhan)(zhan)相比，這種工(gong)藝技術的發(fa)展(zhan)(zhan)顯得(de)快多(duo)了(le)。這25年(nian)(nian)的發(fa)展(zhan)(zhan)歷(li)(li)程可劃分為四個階段(duan)，如表22-3所示。
