Calmes 是在改進方(fang)坯(pi)(pi)連(lian)鑄(zhu)技術和(he)水(shui)壓穿孔技術兩個方(fang)面(mian)技術的(de)基礎上而發展起PPM技術的(de),在PPM發明之前(qian)解決連(lian)鑄(zhu)坯(pi)(pi)穿孔問題的(de)幾個途徑主(zhu)要是:
1. 將連(lian)鑄(zhu)方坯軋成圓坯后,再用(yong)斜軋穿孔(kong);
2. 采用(yong)三輥(gun)式穿孔(kong)機對低碳(tan)鋼(gang)的連鑄坯穿孔(kong),至于其他鋼(gang)種,則用(yong)經過(guo)軋制的連鑄坯進(jin)行穿孔(kong);
3. 在水壓沖(chong)孔(kong)機上對連鑄坯進行沖(chong)孔(kong)。
而(er)PPM可以直(zhi)接對連鑄方坯穿(chuan)孔,這在技術發(fa)展史(shi)上不能不說是一大(da)進(jin)步。
A.H.Calmes 為發展壓力穿孔工藝而做的大量試驗始自20世紀50年代末,于60年代末制成試驗軋機,接著,在Dalmine 不銹鋼管廠(chang)進行了工業性試驗。
1971年(nian)意(yi)(yi)大(da)(da)利(li) Dalmine 廠建立了(le)一(yi)個(ge)由(you)加熱到(dao)壓(ya)(ya)(ya)力穿(chuan)孔(kong)的(de)完整工(gong)業(ye)性試(shi)驗車間,試(shi)驗證明,壓(ya)(ya)(ya)力穿(chuan)孔(kong)工(gong)藝可以(yi)實現連鑄(zhu)方(fang)坯(pi)的(de)穿(chuan)孔(kong)。所以(yi),1978年(nian)8月在意(yi)(yi)大(da)(da)利(li)Bergamo投產的(de)世界上第一(yi)個(ge)MPM軋(ya)管(guan)廠采用了(le)PPM,這臺(tai)壓(ya)(ya)(ya)力穿(chuan)孔(kong)機(ji)軋(ya)輥輥徑為(wei)1280mm,電機(ji)功(gong)率為(wei)500kW,推(tui)(tui)(tui)(tui)料機(ji)的(de)最(zui)大(da)(da)推(tui)(tui)(tui)(tui)力為(wei)2300kN.壓(ya)(ya)(ya)力穿(chuan)孔(kong)機(ji)前設(she)有兩個(ge)導(dao)(dao)向(xiang)裝(zhuang)置(zhi),一(yi)個(ge)是(shi)輥式導(dao)(dao)向(xiang)裝(zhuang)置(zhi),另(ling)一(yi)個(ge)是(shi)板式導(dao)(dao)向(xiang)裝(zhuang)置(zhi)。后者是(shi)日本八幡廠滾動式導(dao)(dao)板裝(zhuang)置(zhi)的(de)一(yi)個(ge)改進,四(si)塊導(dao)(dao)板各由(you)液(ye)壓(ya)(ya)(ya)缸壓(ya)(ya)(ya)向(xiang)鋼(gang)坯(pi),使方(fang)坯(pi)保(bao)持在中心(xin)線上,壓(ya)(ya)(ya)力穿(chuan)孔(kong)機(ji)的(de)推(tui)(tui)(tui)(tui)桿(gan)是(shi)一(yi)根圓棒(bang),前端(duan)有一(yi)個(ge)方(fang)形(xing)推(tui)(tui)(tui)(tui)頭(tou),在推(tui)(tui)(tui)(tui)桿(gan)的(de)中部有一(yi)個(ge)一(yi)段(duan)(duan)1m左右的(de)方(fang)形(xing)截面(mian)的(de)導(dao)(dao)向(xiang)段(duan)(duan),在其四(si)面(mian)鑲(xiang)有可以(yi)更換的(de)耐磨襯板。在推(tui)(tui)(tui)(tui)鋼(gang)時,這一(yi)段(duan)(duan)方(fang)形(xing)導(dao)(dao)向(xiang)段(duan)(duan)不通過軋(ya)輥,而只(zhi)是(shi)在輥式導(dao)(dao)向(xiang)裝(zhuang)置(zhi)中起導(dao)(dao)向(xiang)作用。
壓力穿(chuan)孔頂(ding)頭和頂(ding)桿(gan)擰在(zai)一起,穿(chuan)孔結束后(hou),頂(ding)桿(gan)連同空心坯(pi)一起橫向移出到一條輥道上,在(zai)此(ci)擋住(zhu)穿(chuan)孔坯(pi)而將頂(ding)桿(gan)(及頂(ding)頭)抽出,穿(chuan)孔后(hou)空心坯(pi)的(de)壁厚不(bu)(bu)均(jun)平(ping)均(jun)為15%,經過一次延(yan)伸以(yi)后(hou),空心坯(pi)的(de)壁厚不(bu)(bu)均(jun)可減去70%.因此(ci)荒管的(de)壁厚不(bu)(bu)均(jun)約為±5%,具(ju)體(ti)數據(ju)是:
對(dui)于(yu)壁厚為5.5~6.35mm的鋼管ΔS=±7%;
對于(yu)壁厚為(wei)15~18mm的鋼管ΔS=3.5%.
穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)后(hou)(hou)的(de)(de)(de)(de)(de)(de)空(kong)(kong)心(xin)坯(pi)(pi)要(yao)在(zai)(zai)(zai)延(yan)(yan)伸(shen)機(ji)(ji)(ji)上(shang)延(yan)(yan)伸(shen),減小管(guan)(guan)(guan)壁(bi)厚(hou)度(du),消(xiao)除壁(bi)厚(hou)不(bu)均。在(zai)(zai)(zai)1961年(nian)(nian)進行旨在(zai)(zai)(zai)消(xiao)除壁(bi)厚(hou)不(bu)均的(de)(de)(de)(de)(de)(de)試(shi)(shi)(shi)驗(yan)(yan),采(cai)用了如(ru)上(shang)所述的(de)(de)(de)(de)(de)(de)結(jie)構方(fang)式。后(hou)(hou)的(de)(de)(de)(de)(de)(de)1964~1965年(nian)(nian)在(zai)(zai)(zai)一臺(tai)16英(ying)(ying)(ying)寸(cun)周期軋管(guan)(guan)(guan)機(ji)(ji)(ji)上(shang)進行軋管(guan)(guan)(guan)試(shi)(shi)(shi)驗(yan)(yan),其(qi)簡(jian)況如(ru)下:管(guan)(guan)(guan)坯(pi)(pi)為(wei)(wei)(wei)(wei)包括(kuo)不(bu)銹鋼(gang)在(zai)(zai)(zai)內的(de)(de)(de)(de)(de)(de)各種(zhong)鋼(gang)種(zhong)的(de)(de)(de)(de)(de)(de)6~5/8英(ying)(ying)(ying)寸(cun)方(fang)鋼(gang)錠,穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)后(hou)(hou)空(kong)(kong)心(xin)坯(pi)(pi)的(de)(de)(de)(de)(de)(de)外(wai)徑(jing)(jing)為(wei)(wei)(wei)(wei)8 1/4英(ying)(ying)(ying)寸(cun),壁(bi)厚(hou)為(wei)(wei)(wei)(wei)2英(ying)(ying)(ying)寸(cun),當L/I·D為(wei)(wei)(wei)(wei)12.5時,仍(reng)然可獲(huo)得(de)壁(bi)厚(hou)均勻的(de)(de)(de)(de)(de)(de)空(kong)(kong)心(xin)坯(pi)(pi)。在(zai)(zai)(zai)1966年(nian)(nian)開始設計、制造(zao)工藝性試(shi)(shi)(shi)驗(yan)(yan)的(de)(de)(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji),在(zai)(zai)(zai)1969年(nian)(nian)制成(cheng)試(shi)(shi)(shi)驗(yan)(yan)用的(de)(de)(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji),所穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)的(de)(de)(de)(de)(de)(de)空(kong)(kong)心(xin)坯(pi)(pi)外(wai)徑(jing)(jing)為(wei)(wei)(wei)(wei)10~16 1/2英(ying)(ying)(ying)寸(cun)。鑒于采(cai)用連(lian)鑄方(fang)坯(pi)(pi)生(sheng)產無縫鋼(gang)管(guan)(guan)(guan)的(de)(de)(de)(de)(de)(de)重要(yao)意(yi)義(yi),將1968年(nian)(nian)試(shi)(shi)(shi)驗(yan)(yan)計劃的(de)(de)(de)(de)(de)(de)重點放在(zai)(zai)(zai)連(lian)鑄坯(pi)(pi)的(de)(de)(de)(de)(de)(de)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)上(shang),接(jie)著采(cai)用各種(zhong)鋼(gang)種(zhong),特(te)別是在(zai)(zai)(zai)斜軋穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji)上(shang)難以(yi)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)的(de)(de)(de)(de)(de)(de)鋼(gang)種(zhong),進行了大量(liang)的(de)(de)(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)試(shi)(shi)(shi)驗(yan)(yan),其(qi)結(jie)果(guo)如(ru)下:9 1/2英(ying)(ying)(ying)寸(cun)連(lian)鑄方(fang)坯(pi)(pi),經過(guo)(guo)加熱(re)、定心(xin)、定型和(he)(he)清(qing)除氧化鐵皮后(hou)(hou),在(zai)(zai)(zai)壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji)穿(chuan)(chuan)(chuan)成(cheng)空(kong)(kong)心(xin)坯(pi)(pi),其(qi)外(wai)徑(jing)(jing)為(wei)(wei)(wei)(wei)11 3/4英(ying)(ying)(ying)寸(cun),內徑(jing)(jing)為(wei)(wei)(wei)(wei)6英(ying)(ying)(ying)寸(cun),方(fang)坯(pi)(pi)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)時的(de)(de)(de)(de)(de)(de)延(yan)(yan)伸(shen)系數為(wei)(wei)(wei)(wei)1.08~1.18,通過(guo)(guo)軋輥(gun)孔(kong)(kong)(kong)(kong)型以(yi)及出(chu)口(kou)導(dao)套的(de)(de)(de)(de)(de)(de)變換,可以(yi)改變空(kong)(kong)心(xin)坯(pi)(pi)的(de)(de)(de)(de)(de)(de)外(wai)徑(jing)(jing)和(he)(he)延(yan)(yan)伸(shen)系數。當延(yan)(yan)伸(shen)系數為(wei)(wei)(wei)(wei)1.10時所得(de)的(de)(de)(de)(de)(de)(de)結(jie)果(guo)為(wei)(wei)(wei)(wei)最(zui)好(hao),截(jie)面(mian)也(ye)較(jiao)圓。但應指出(chu),壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)法的(de)(de)(de)(de)(de)(de)目的(de)(de)(de)(de)(de)(de)并(bing)不(bu)在(zai)(zai)(zai)于獲(huo)得(de)完(wan)全圓的(de)(de)(de)(de)(de)(de)空(kong)(kong)心(xin)坯(pi)(pi)和(he)(he)較(jiao)巨(ju)大的(de)(de)(de)(de)(de)(de)延(yan)(yan)長率,而是在(zai)(zai)(zai)不(bu)使金屬結(jie)構受到(dao)(dao)不(bu)利的(de)(de)(de)(de)(de)(de)應力(li)(li)(li)(li)狀態下,將方(fang)形(xing)(xing)鑄坯(pi)(pi)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)成(cheng)為(wei)(wei)(wei)(wei)內表面(mian)質量(liang)良好(hao)的(de)(de)(de)(de)(de)(de)圓形(xing)(xing)空(kong)(kong)心(xin)坯(pi)(pi),最(zui)大的(de)(de)(de)(de)(de)(de)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)比(bi)(bi)L/I·D可達(da)24,而在(zai)(zai)(zai)水(shui)壓(ya)(ya)(ya)(ya)沖孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji)上(shang),穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)比(bi)(bi)僅為(wei)(wei)(wei)(wei)6,若其(qi)后(hou)(hou)設置延(yan)(yan)伸(shen)機(ji)(ji)(ji),也(ye)只能達(da)到(dao)(dao)9,在(zai)(zai)(zai)壓(ya)(ya)(ya)(ya)力(li)(li)(li)(li)穿(chuan)(chuan)(chuan)孔(kong)(kong)(kong)(kong)機(ji)(ji)(ji)上(shang),雖然L/I·D值很高,但其(qi)壁(bi)厚(hou)的(de)(de)(de)(de)(de)(de)偏(pian)差仍(reng)在(zai)(zai)(zai)允許范圍內。
除(chu)了加熱均勻與否以外,影響壁(bi)厚不均程度的主要因素是:
1. 設計方面的因素(su) 入口導(dao)套(tao)(tao)、出口導(dao)套(tao)(tao)、軋輥(gun)孔(kong)型、頂桿的中心要在一條直線上;
2. 工具方面的因素 要將(jiang)穿孔工具的公差(cha)值減至最小;
3. 定心問題 在方坯的(de)前(qian)端要(yao)有一個準(zhun)確的(de)中心孔(kong);
4. 穿孔頂頭和頂桿的強度(du)問(wen)題 當(dang)方坯(pi)加熱溫度(du)為2300~2360 ℉時,頂桿的單位載荷不應超(chao)過65kg/m㎡.

