限(xian)動芯棒(bang)連軋(ya)管工藝被稱作“Retained mandrel mill”或(huo)“Multi-stand pipe mill”（簡稱MPM),前者(zhe)是從芯棒(bang)運動受控(kong)這一特點(dian)出發的，故稱為“限(xian)動芯棒(bang)連軋(ya)管工藝”，后者(zhe)是從Calmes 取名的“Multi-stand pilger mill”中“Pilger”變(bian)以“Pipe”演(yan)變(bian)而來的。由(you)于這一歷史原因，這種軋(ya)機簡稱為 MPM軋(ya)機，而不是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(gong)藝設備特征
a. MPM軋機的(de)特征
MPM軋(ya)機(ji)采(cai)用機(ji)械限(xian)(xian)動(dong)(dong)(dong)(dong)(dong)式芯(xin)(xin)棒(bang)速(su)(su)(su)(su)度(du)控(kong)制裝(zhuang)置，芯(xin)(xin)棒(bang)的(de)(de)快(kuai)速(su)(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)作(zuo)（穿心(xin)棒(bang)、抽芯(xin)(xin)棒(bang)）及限(xian)(xian)動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作(zuo)（軋(ya)制時控(kong)制芯(xin)(xin)棒(bang)速(su)(su)(su)(su)度(du)）靠36m長的(de)(de)大(da)齒(chi)(chi)(chi)條(tiao)來實(shi)現(xian)。快(kuai)速(su)(su)(su)(su)動(dong)(dong)(dong)(dong)(dong)作(zuo)由(you)兩臺(tai)500kW直流(liu)電機(ji)分別(bie)驅(qu)動(dong)(dong)(dong)(dong)(dong)兩個齒(chi)(chi)(chi)輪，從(cong)齒(chi)(chi)(chi)條(tiao)的(de)(de)上(shang)下側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)條(tiao)運(yun)動(dong)(dong)(dong)(dong)(dong)。限(xian)(xian)動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作(zuo)時，由(you)8個齒(chi)(chi)(chi)輪（上(shang)下各(ge)4個）從(cong)齒(chi)(chi)(chi)條(tiao)的(de)(de)上(shang)下側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)條(tiao)運(yun)動(dong)(dong)(dong)(dong)(dong)，每(mei)個齒(chi)(chi)(chi)輪均由(you)1臺(tai)110kW直流(liu)電機(ji)單獨(du)傳動(dong)(dong)(dong)(dong)(dong)。芯(xin)(xin)棒(bang)運(yun)動(dong)(dong)(dong)(dong)(dong)方式的(de)(de)改(gai)變依(yi)靠氣動(dong)(dong)(dong)(dong)(dong)離合器分別(bie)接通或脫開相應的(de)(de)齒(chi)(chi)(chi)輪來實(shi)現(xian)。芯(xin)(xin)棒(bang)的(de)(de)快(kuai)速(su)(su)(su)(su)行程速(su)(su)(su)(su)度(du)為6m/s,限(xian)(xian)動(dong)(dong)(dong)(dong)(dong)速(su)(su)(su)(su)度(du)為0.2~0.5m/s,限(xian)(xian)動(dong)(dong)(dong)(dong)(dong)工作(zuo)行程為5.0~5.2m.
在Dalmine公(gong)司進行試驗時(shi)，芯(xin)(xin)棒(bang)的(de)運(yun)動(dong)速(su)度采用液壓(ya)控制。但因液壓(ya)系統控制芯(xin)(xin)棒(bang)速(su)度不夠穩定，有芯(xin)(xin)棒(bang)斷續運(yun)動(dong)的(de)情況，隨后改為齒(chi)輪齒(chi)條(tiao)傳動(dong)的(de)機械系統。
MPM的軋(ya)輥孔型采用(yong)比普通(tong)連軋(ya)機開口角稍小的封閉式圓孔（帶弧(hu)形開口），可(ke)以采用(yong)較大的伸長率。
b. 脫(tuo)管機的特征
MPM的(de)(de)脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)與(yu)二(er)輥式定(ding)徑(jing)(jing)機(ji)(ji)(ji)相同(tong)，由于MPM主(zhu)軋(ya)機(ji)(ji)(ji)的(de)(de)第(di)(di)七、八(ba)機(ji)(ji)(ji)架(jia)(jia)的(de)(de)壓下量很小，僅靠第(di)(di)七、八(ba)機(ji)(ji)(ji)架(jia)(jia)軋(ya)輥的(de)(de)作用無法推送管(guan)(guan)子前進(jin)和(he)(he)使(shi)管(guan)(guan)子從芯棒前端脫(tuo)(tuo)(tuo)(tuo)出，故在MPM工藝中(zhong)設置幾(ji)架(jia)(jia)脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)，起脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)和(he)(he)定(ding)徑(jing)(jing)的(de)(de)作用。脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)(de)軋(ya)輥直徑(jing)(jing)為(wei)720~850mm,輥身長(chang)420mm,第(di)(di)一、三架(jia)(jia)由1臺(tai)450kW的(de)(de)直流(liu)電(dian)(dian)機(ji)(ji)(ji)驅動(dong)(dong)，而(er)第(di)(di)二(er)架(jia)(jia)則單(dan)獨由1臺(tai)同(tong)型號電(dian)(dian)機(ji)(ji)(ji)驅動(dong)(dong)。脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)速度必須按連(lian)軋(ya)原則確定(ding)，并(bing)與(yu)MPM軋(ya)機(ji)(ji)(ji)的(de)(de)第(di)(di)八(ba)機(ji)(ji)(ji)架(jia)(jia)保持電(dian)(dian)氣連(lian)鎖。脫(tuo)(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)(ji)的(de)(de)減徑(jing)(jing)率(lv)為(wei)3.5%~4.6%,孔型與(yu)一般二(er)輥式定(ding)徑(jing)(jing)直機(ji)(ji)(ji)相同(tong)。
c. MPM工藝的芯棒運動特征
軋制過(guo)程中，要(yao)控制芯(xin)棒(bang)(bang)(bang)(bang)的速度(du)，使其處于恒定狀態。雖然(ran)芯(xin)棒(bang)(bang)(bang)(bang)也隨管(guan)子(zi)(zi)前進，但其前進速度(du)應遠(yuan)小于管(guan)子(zi)(zi)的速度(du)，軋制結(jie)束(shu)(shu)后(hou)被(bei)抽出返(fan)回。軋制28m長的管(guan)子(zi)(zi)時，芯(xin)棒(bang)(bang)(bang)(bang)長度(du)為(wei)(wei)12m.芯(xin)棒(bang)(bang)(bang)(bang)為(wei)(wei)中空(kong)水(shui)冷芯(xin)棒(bang)(bang)(bang)(bang)，軋制結(jie)束(shu)(shu)后(hou)，芯(xin)棒(bang)(bang)(bang)(bang)溫度(du)為(wei)(wei)400℃,需(xu)要(yao)采(cai)用(yong)內外噴水(shui)使之均勻冷卻。
2. 限動芯棒(bang)連軋(ya)管工(gong)藝技(ji)術(shu)發展的4個階段(duan)
不銹鋼管(guan)限動芯(xin)棒(bang)連(lian)(lian)軋(ya)管(guan)工(gong)藝的技(ji)術(shu)(shu)發展(zhan)史應(ying)溯(su)自(zi)1890年，Pfeiffer在一篇(pian)文章中(zhong)寫道(dao)：“1890年發明家Heckert 申請了連(lian)(lian)軋(ya)技(ji)術(shu)(shu)專利(li)，該(gai)技(ji)術(shu)(shu)采用(yong)十架兩輥高速軋(ya)機固定芯(xin)棒(bang)軋(ya)制空心管(guan)坯。可(ke)見在Calmes 多(duo)機架軋(ya)管(guan)機問世(shi)前(qian)80年，就已有了雛(chu)形。”1968年A.H.Calmes 取(qu)得了MPM連(lian)(lian)軋(ya)管(guan)工(gong)藝的權利(li)，10年后，第一套MPM連(lian)(lian)軋(ya)管(guan)機在Dalmine Bergamo 鋼管(guan)廠(chang)投產，到2003年12月天津(jin)無縫不銹鋼管(guan)廠(chang)三輥式(shi)限動芯(xin)棒(bang)連(lian)(lian)軋(ya)管(guan)機投產，已經歷了整(zheng)整(zheng)25年的時間，和全浮動芯(xin)棒(bang)連(lian)(lian)軋(ya)管(guan)技(ji)術(shu)(shu)的發展(zhan)相比，這種工(gong)藝技(ji)術(shu)(shu)的發展(zhan)顯得快多(duo)了。這25年的發展(zhan)歷程可(ke)劃分為四(si)個階段，如(ru)表(biao)22-3所示。
