浙江至德鋼業有限公司不銹鋼管生產技術人員發現,在張力減徑機上生產不(bu)銹鋼厚壁管的主要限制是產品質量問題,當生產D/S值為3.5~5.0的不銹鋼厚壁管時,內孔變(六)方的現象比較嚴重,對張力減徑機成品管質量的威脅很大,但這可采用較小的減徑率和橢圓度較小的孔型來解決。


 至德(de)鋼(gang)業通過調節軋(ya)(ya)輥或(huo)傳(chuan)動(dong)電機的(de)(de)轉(zhuan)速而獲(huo)得的(de)(de)軸向張(zhang)(zhang)力不(bu)(bu)(bu)(bu)僅(jin)是(shi)控制(zhi)壁(bi)厚(hou),而且是(shi)改善不(bu)(bu)(bu)(bu)銹鋼(gang)管(guan)(guan)質量(liang)的(de)(de)最佳手(shou)段。由(you)(you)于(yu)張(zhang)(zhang)力值限制(zhi)了不(bu)(bu)(bu)(bu)銹鋼(gang)管(guan)(guan)內(nei)表面(mian)(mian)的(de)(de)自由(you)(you)變形(xing)(xing)(xing)(xing),所(suo)以也就(jiu)能防止內(nei)表面(mian)(mian)出現軋(ya)(ya)制(zhi)缺陷。張(zhang)(zhang)力減(jian)徑(jing)(jing)薄(bo)壁(bi)管(guan)(guan)時所(suo)采用的(de)(de)張(zhang)(zhang)力值應考慮周向壓應力過大時所(suo)出現的(de)(de)徑(jing)(jing)向壓垮現象。此外(wai),在張(zhang)(zhang)力減(jian)徑(jing)(jing)工藝過程中(zhong)通常在軋(ya)(ya)件(jian)截面(mian)(mian)內(nei)發生(sheng)(sheng)不(bu)(bu)(bu)(bu)均勻(yun)變形(xing)(xing)(xing)(xing),從而導致鋼(gang)管(guan)(guan)內(nei)表面(mian)(mian)出現或(huo)多或(huo)少的(de)(de)內(nei)多邊形(xing)(xing)(xing)(xing)(圖(tu)11-2),但是(shi),通過正確調節張(zhang)(zhang)力值,在不(bu)(bu)(bu)(bu)均勻(yun)變形(xing)(xing)(xing)(xing)區實現有(you)效(xiao)的(de)(de)減(jian)徑(jing)(jing)量(liang)仍(reng)是(shi)有(you)可能的(de)(de)。這(zhe)種變形(xing)(xing)(xing)(xing)的(de)(de)不(bu)(bu)(bu)(bu)均勻(yun)性(xing)是(shi)由(you)(you)于(yu)與(yu)幾何形(xing)(xing)(xing)(xing)狀有(you)關的(de)(de)一些因素,如減(jian)徑(jing)(jing)率、摩擦條(tiao)件(jian)以及變形(xing)(xing)(xing)(xing)抗力等(deng)引起的(de)(de),由(you)(you)于(yu)軋(ya)(ya)輥布(bu)置的(de)(de)交替性(xing),一方(fang)面(mian)(mian)在軋(ya)(ya)槽底部(bu)和側(ce)邊開(kai)口部(bu)具(ju)有(you)不(bu)(bu)(bu)(bu)同(tong)(tong)的(de)(de)變形(xing)(xing)(xing)(xing)條(tiao)件(jian),另一方(fang)面(mian)(mian)處于(yu)這(zhe)兩點(dian)之(zhi)間的(de)(de)中(zhong)間部(bu)分的(de)(de)變形(xing)(xing)(xing)(xing)亦不(bu)(bu)(bu)(bu)同(tong)(tong)于(yu)這(zhe)兩點(dian)的(de)(de)變形(xing)(xing)(xing)(xing)。因此,當生(sheng)(sheng)產不(bu)(bu)(bu)(bu)銹鋼(gang)厚(hou)壁(bi)管(guan)(guan)(即S/D值較大)時,內(nei)多邊形(xing)(xing)(xing)(xing)現象特(te)別(bie)嚴重,不(bu)(bu)(bu)(bu)銹鋼(gang)管(guan)(guan)內(nei)表面(mian)(mian)形(xing)(xing)(xing)(xing)狀與(yu)圓形(xing)(xing)(xing)(xing)的(de)(de)差異更明顯。


圖 11-2.jpg


 浙江(jiang)至德鋼業(ye)有(you)限公司技術人員將相對于軋輥(gun)布置的(de)(de)內(nei)多邊形的(de)(de)劇烈程度和位置定義(yi)為P(圖(tu)11-2)。當孔型設計中采(cai)用較(jiao)(jiao)(jiao)大(da)的(de)(de)橢圓(yuan)度即α值(zhi)時,當以(yi)下各參數(shu)發生(sheng)變化時,如(1)不(bu)銹鋼管直徑(jing)較(jiao)(jiao)(jiao)大(da)(假定D/S比為定值(zhi));(2)軋輥(gun)直徑(jing)較(jiao)(jiao)(jiao)小;(3)張力(li)值(zhi)較(jiao)(jiao)(jiao)大(da);(4)D/S比較(jiao)(jiao)(jiao)小;(5)單架減徑(jing)率較(jiao)(jiao)(jiao)大(da),則(ze)P值(zhi)增(zeng)大(da)。此(ci)外,P值(zhi)的(de)(de)絕(jue)對值(zhi)隨著以(yi)下各參數(shu)的(de)(de)增(zeng)大(da)而增(zeng)大(da):(1)孔型的(de)(de)橢圓(yuan)增(zeng)大(da)時;(2)總減徑(jing)量(liang)增(zeng)大(da)時。