限動芯(xin)棒(bang)連軋管(guan)工藝被稱(cheng)(cheng)(cheng)作(zuo)“Retained mandrel mill”或(huo)“Multi-stand pipe mill”（簡(jian)稱(cheng)(cheng)(cheng)MPM),前者是(shi)從(cong)(cong)芯(xin)棒(bang)運動受控(kong)這一(yi)特點出(chu)發的，故稱(cheng)(cheng)(cheng)為“限動芯(xin)棒(bang)連軋管(guan)工藝”，后者是(shi)從(cong)(cong)Calmes 取名的“Multi-stand pilger mill”中“Pilger”變以“Pipe”演變而來的。由于這一(yi)歷(li)史原因，這種軋機簡(jian)稱(cheng)(cheng)(cheng)為 MPM軋機，而不是(shi)RMM.
采用這種工藝軋管，連軋不(bu)銹(xiu)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(yi)設備特征
a. MPM軋機的(de)特征(zheng)
MPM軋機(ji)(ji)(ji)采用(yong)機(ji)(ji)(ji)械限動(dong)(dong)(dong)(dong)(dong)式芯(xin)棒(bang)(bang)速(su)度(du)控制裝置，芯(xin)棒(bang)(bang)的(de)(de)(de)快(kuai)速(su)動(dong)(dong)(dong)(dong)(dong)作(zuo)（穿心棒(bang)(bang)、抽芯(xin)棒(bang)(bang)）及限動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作(zuo)（軋制時控制芯(xin)棒(bang)(bang)速(su)度(du)）靠36m長的(de)(de)(de)大齒(chi)(chi)(chi)(chi)(chi)條(tiao)(tiao)(tiao)來(lai)(lai)實現(xian)。快(kuai)速(su)動(dong)(dong)(dong)(dong)(dong)作(zuo)由(you)(you)(you)兩臺500kW直流電機(ji)(ji)(ji)分別驅(qu)動(dong)(dong)(dong)(dong)(dong)兩個齒(chi)(chi)(chi)(chi)(chi)輪，從齒(chi)(chi)(chi)(chi)(chi)條(tiao)(tiao)(tiao)的(de)(de)(de)上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)(chi)條(tiao)(tiao)(tiao)運(yun)動(dong)(dong)(dong)(dong)(dong)。限動(dong)(dong)(dong)(dong)(dong)動(dong)(dong)(dong)(dong)(dong)作(zuo)時，由(you)(you)(you)8個齒(chi)(chi)(chi)(chi)(chi)輪（上(shang)下(xia)各(ge)4個）從齒(chi)(chi)(chi)(chi)(chi)條(tiao)(tiao)(tiao)的(de)(de)(de)上(shang)下(xia)側帶動(dong)(dong)(dong)(dong)(dong)齒(chi)(chi)(chi)(chi)(chi)條(tiao)(tiao)(tiao)運(yun)動(dong)(dong)(dong)(dong)(dong)，每個齒(chi)(chi)(chi)(chi)(chi)輪均由(you)(you)(you)1臺110kW直流電機(ji)(ji)(ji)單獨傳(chuan)動(dong)(dong)(dong)(dong)(dong)。芯(xin)棒(bang)(bang)運(yun)動(dong)(dong)(dong)(dong)(dong)方(fang)式的(de)(de)(de)改變依靠氣動(dong)(dong)(dong)(dong)(dong)離合(he)器分別接通或脫開相應的(de)(de)(de)齒(chi)(chi)(chi)(chi)(chi)輪來(lai)(lai)實現(xian)。芯(xin)棒(bang)(bang)的(de)(de)(de)快(kuai)速(su)行程(cheng)速(su)度(du)為(wei)6m/s,限動(dong)(dong)(dong)(dong)(dong)速(su)度(du)為(wei)0.2~0.5m/s,限動(dong)(dong)(dong)(dong)(dong)工作(zuo)行程(cheng)為(wei)5.0~5.2m.
在Dalmine公司進行試(shi)驗(yan)時，芯棒(bang)的運動(dong)速度采用液壓控(kong)制。但因液壓系(xi)統控(kong)制芯棒(bang)速度不夠穩定，有芯棒(bang)斷續運動(dong)的情況，隨后改為齒輪齒條傳動(dong)的機械(xie)系(xi)統。
MPM的軋(ya)輥孔(kong)型采(cai)用比(bi)普通(tong)連軋(ya)機開口(kou)角稍小的封閉式(shi)圓孔(kong)（帶弧形開口(kou)），可以采(cai)用較(jiao)大(da)的伸長率(lv)。
b. 脫管機的(de)特征(zheng)
MPM的(de)脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)與(yu)(yu)二輥(gun)式(shi)定(ding)(ding)徑(jing)機(ji)(ji)相同，由于MPM主(zhu)軋(ya)機(ji)(ji)的(de)第(di)七、八(ba)機(ji)(ji)架(jia)(jia)的(de)壓下量(liang)很小，僅靠第(di)七、八(ba)機(ji)(ji)架(jia)(jia)軋(ya)輥(gun)的(de)作用(yong)無法推送(song)管(guan)(guan)子(zi)前(qian)進和使管(guan)(guan)子(zi)從芯棒前(qian)端(duan)脫(tuo)(tuo)(tuo)出，故(gu)在MPM工藝中設置幾(ji)架(jia)(jia)脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)，起脫(tuo)(tuo)(tuo)管(guan)(guan)和定(ding)(ding)徑(jing)的(de)作用(yong)。脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)的(de)軋(ya)輥(gun)直徑(jing)為720~850mm,輥(gun)身(shen)長(chang)420mm,第(di)一、三(san)架(jia)(jia)由1臺450kW的(de)直流電機(ji)(ji)驅動，而第(di)二架(jia)(jia)則單(dan)獨由1臺同型(xing)號電機(ji)(ji)驅動。脫(tuo)(tuo)(tuo)管(guan)(guan)速度必(bi)須按連軋(ya)原則確定(ding)(ding)，并與(yu)(yu)MPM軋(ya)機(ji)(ji)的(de)第(di)八(ba)機(ji)(ji)架(jia)(jia)保持電氣連鎖。脫(tuo)(tuo)(tuo)管(guan)(guan)機(ji)(ji)的(de)減徑(jing)率為3.5%~4.6%,孔(kong)型(xing)與(yu)(yu)一般二輥(gun)式(shi)定(ding)(ding)徑(jing)直機(ji)(ji)相同。
c. MPM工藝的芯棒運動(dong)特征
軋制過程中，要控制芯(xin)(xin)(xin)棒(bang)(bang)的(de)速度(du)，使其(qi)處于(yu)恒定(ding)狀態。雖然(ran)芯(xin)(xin)(xin)棒(bang)(bang)也(ye)隨管子(zi)前(qian)進，但其(qi)前(qian)進速度(du)應遠小于(yu)管子(zi)的(de)速度(du)，軋制結(jie)束后(hou)被(bei)抽出返回(hui)。軋制28m長的(de)管子(zi)時，芯(xin)(xin)(xin)棒(bang)(bang)長度(du)為12m.芯(xin)(xin)(xin)棒(bang)(bang)為中空水(shui)冷芯(xin)(xin)(xin)棒(bang)(bang)，軋制結(jie)束后(hou)，芯(xin)(xin)(xin)棒(bang)(bang)溫(wen)度(du)為400℃,需要采用內外噴水(shui)使之均(jun)勻(yun)冷卻。
2. 限動芯(xin)棒(bang)連軋管工藝(yi)技術(shu)發展的4個階段
不(bu)銹(xiu)鋼(gang)管(guan)(guan)限動芯(xin)(xin)(xin)棒(bang)(bang)連(lian)軋(ya)(ya)管(guan)(guan)工藝的(de)(de)技(ji)術(shu)(shu)發展(zhan)史應溯自1890年(nian)(nian)(nian)，Pfeiffer在一篇文章中寫道：“1890年(nian)(nian)(nian)發明家(jia)Heckert 申(shen)請(qing)了連(lian)軋(ya)(ya)技(ji)術(shu)(shu)專利，該技(ji)術(shu)(shu)采用十架(jia)兩輥高速軋(ya)(ya)機固定(ding)芯(xin)(xin)(xin)棒(bang)(bang)軋(ya)(ya)制空心管(guan)(guan)坯。可見(jian)在Calmes 多(duo)機架(jia)軋(ya)(ya)管(guan)(guan)機問(wen)世前80年(nian)(nian)(nian)，就(jiu)已有(you)了雛形。”1968年(nian)(nian)(nian)A.H.Calmes 取得了MPM連(lian)軋(ya)(ya)管(guan)(guan)工藝的(de)(de)權利，10年(nian)(nian)(nian)后，第一套MPM連(lian)軋(ya)(ya)管(guan)(guan)機在Dalmine Bergamo 鋼(gang)管(guan)(guan)廠投產(chan)，到2003年(nian)(nian)(nian)12月天津(jin)無縫不(bu)銹(xiu)鋼(gang)管(guan)(guan)廠三輥式(shi)限動芯(xin)(xin)(xin)棒(bang)(bang)連(lian)軋(ya)(ya)管(guan)(guan)機投產(chan)，已經(jing)歷(li)了整(zheng)(zheng)整(zheng)(zheng)25年(nian)(nian)(nian)的(de)(de)時間，和(he)全(quan)浮動芯(xin)(xin)(xin)棒(bang)(bang)連(lian)軋(ya)(ya)管(guan)(guan)技(ji)術(shu)(shu)的(de)(de)發展(zhan)相比，這種工藝技(ji)術(shu)(shu)的(de)(de)發展(zhan)顯得快多(duo)了。這25年(nian)(nian)(nian)的(de)(de)發展(zhan)歷(li)程(cheng)可劃分為四個階段，如(ru)表(biao)22-3所示。
