立式不銹鋼管穿(擴)孔機的工模具配置取決于穿(擴)孔機的結構形式,穿(擴)孔過程的工藝要求,以及穿(擴)孔時坯料金屬變形時的流動特點。和臥式擠壓機的工模具配置一樣,穿(擴)孔機工模具配置的基本形式由穿(擴)孔筒(內襯和外套)、鐓粗桿、鐓粗頭、穿(擴)孔頭、支承桿、支承頭、剪切環以及連接件組成,如圖7-50所示。

一(yi)、穿(擴)孔筒
當不銹鋼管(guan)坯料進行穿和擴孔時,穿孔筒內襯承受相當小的單位壓力(不大于590MPa).因為從坯料穿孔或擴孔方向的垂直滑移摩擦力實際上是沒有的。但是,因與加熱到高溫的坯料直接接觸時間長達30s,引起穿孔筒內襯劇烈受熱。長久使用后的穿孔筒內襯以焊瘤的形式引起變形而損壞,或使穿孔坯料取出產生困難。因此,當其在高速工作時應采取強制冷卻的方法來降低穿孔筒內襯的溫度。通常在穿孔筒外套的內壁車有螺旋冷卻水槽(圖7-51)來冷卻內襯。

一般穿孔筒(tong)的內(nei)襯與外套之(zhi)間以1.0%~1.5%的錐度相配合,而(er)內(nei)襯的內(nei)孔也制成約有1%~3%的錐度,這樣使取出坯料(liao)時能比較順利地(di)頂出。
另外(wai),穿孔(kong)筒內(nei)襯的內(nei)表面光(guang)潔度要求比較高,熱(re)處理(li)后要進行磨削。其熱(re)處理(li)后的硬度約(yue)為(wei)HRC42~45,以(yi)提高其耐(nai)磨性(xing)。
穿孔筒的(de)內(nei)襯采用和擠壓筒內(nei)襯相(xiang)同的(de)材料制(zhi)造,如5CrW2Si或Ni11.一般穿孔筒內(nei)襯的(de)使用壽命大約為(wei)1000~3000次。
從穿(chuan)(chuan)孔筒(tong)內襯的(de)(de)工(gong)作條件來考量,采用具(ju)有雙(shuang)穿(chuan)(chuan)孔筒(tong)旋轉輪換工(gong)作結構的(de)(de)穿(chuan)(chuan)孔機(ji)最(zui)為合適(shi)。
原因為除了(le)能使(shi)穿(chuan)孔筒得到及時(shi)而充分的冷卻(que)之外,輪流使(shi)用(yong)的穿(chuan)孔筒有利于內(nei)(nei)襯(chen)很好地(di)清(qing)除玻璃潤(run)滑(hua)劑殘渣,提(ti)高內(nei)(nei)襯(chen)的使(shi)用(yong)壽命。
二(er)、鐓粗桿和穿孔桿
1. 鐓粗桿(gan)和穿孔桿(gan)的結構
鐓(dui)粗(cu)桿在(zai)結構上,上端用銷子或夾(jia)緊裝(zhuang)置固(gu)定在(zai)鐓(dui)粗(cu)梁上,下端用螺紋連接(jie)鐓(dui)粗(cu)頭(圖7-52),其內孔(kong)(kong)設(she)有導(dao)向滑槽(cao)與穿孔(kong)(kong)桿相(xiang)配合。

鐓粗桿的外徑比(bi)穿孔筒小10~30mm,而(er)內(nei)徑比(bi)穿孔桿大5~25mm.但考慮到(dao)鐓粗桿的共用(yong)性,可(ke)在保證強度的條件下超出上(shang)述范圍。
鐓粗桿的(de)(de)長度(du)應根據穿(chuan)孔筒(tong)的(de)(de)長度(du)和(he)生產最短的(de)(de)坯料長度(du)來決定。
根據穿(chuan)(chuan)孔(kong)桿(gan)和穿(chuan)(chuan)孔(kong)頭(tou)的(de)(de)規(gui)格,可以(yi)(yi)更換(huan)鐓粗頭(tou),以(yi)(yi)擴大鐓粗桿(gan)的(de)(de)使用范圍(wei),鐓粗頭(tou)的(de)(de)外徑與穿(chuan)(chuan)孔(kong)筒的(de)(de)內(nei)徑之間(jian)間(jian)隙(xi)要(yao)小,約(yue)比穿(chuan)(chuan)孔(kong)筒的(de)(de)小頭(tou)直徑小0.5~1.5mm,其內(nei)孔(kong)帶(dai)有花鍵式(shi)導向槽。
2. 穿孔(kong)桿的穩定性(xing)強度(du)校核
立(li)式穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)機的(de)穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)桿作為連(lian)(lian)桿,連(lian)(lian)接(jie)穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)頭(tou)及芯棒支承,穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)并(bing)(bing)不(bu)和(he)變形屬(shu)直(zhi)(zhi)接(jie)接(jie)觸。在穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)過程(cheng)中,穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)桿連(lian)(lian)接(jie)并(bing)(bing)支承著穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)頭(tou)及擴孔(kong)(kong)頭(tou)。一般(ban)穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)桿的(de)直(zhi)(zhi)徑(jing)比穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)頭(tou)工作帶的(de)直(zhi)(zhi)徑(jing)小10~30mm.穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)桿的(de)長度取決于(yu)穿(chuan)(chuan)(chuan)(chuan)孔(kong)(kong)筒的(de)長度。
由于(yu)在不銹鋼管穿(chuan)(chuan)孔時穿(chuan)(chuan)孔桿承受壓(ya)縮(suo)應力,且因穿(chuan)(chuan)孔桿的長度較長,工作時上(shang)端相當(dang)于(yu)固定。因此,其彎曲的危險(xian)性要比壓(ya)縮(suo)變形的危險(xian)性更大。
所以,穿(chuan)孔桿(gan)的強度(du)校(xiao)核是按照壓桿(gan)穩定的方法來計算。
穿孔(kong)桿上所承(cheng)受的應力為:

3. 穿孔頭和擴孔頭
a. 穿(chuan)孔頭和擴孔頭的結構
在立(li)式穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)機對實心坯(pi)料(liao)進(jin)行(xing)穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)時(shi),采(cai)用(yong)穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)工(gong)(gong)藝,需(xu)用(yong)穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)頭(tou);而對帶預鉆孔(kong)(kong)(kong)(kong)(kong)的(de)(de)空心坯(pi)料(liao)進(jin)行(xing)擴(kuo)孔(kong)(kong)(kong)(kong)(kong)時(shi),采(cai)用(yong)擴(kuo)孔(kong)(kong)(kong)(kong)(kong)工(gong)(gong)藝,則需(xu)用(yong)擴(kuo)孔(kong)(kong)(kong)(kong)(kong)頭(tou)。在采(cai)用(yong)穿(chuan)(chuan)(擴(kuo))孔(kong)(kong)(kong)(kong)(kong)工(gong)(gong)藝時(shi),穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)頭(tou)和(he)擴(kuo)孔(kong)(kong)(kong)(kong)(kong)頭(tou)都安裝在穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)桿上。對于穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)機的(de)(de)工(gong)(gong)模具(ju)而言,穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)頭(tou)的(de)(de)工(gong)(gong)作條(tiao)件最為嚴酷,受到(dao)(dao)最為強烈(lie)的(de)(de)磨損;而擴(kuo)孔(kong)(kong)(kong)(kong)(kong)頭(tou)的(de)(de)工(gong)(gong)作條(tiao)件相對會好一些(xie)。因(yin)此,擴(kuo)孔(kong)(kong)(kong)(kong)(kong)頭(tou)的(de)(de)使用(yong)壽命(ming)(ming)要(yao)比穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)頭(tou)長。一般在生產(chan)不銹(xiu)鋼管時(shi),穿(chuan)(chuan)孔(kong)(kong)(kong)(kong)(kong)頭(tou)的(de)(de)使用(yong)壽命(ming)(ming)不超過30~40次(ci)/只,而擴(kuo)孔(kong)(kong)(kong)(kong)(kong)頭(tou)的(de)(de)使用(yong)壽命(ming)(ming)可以達(da)到(dao)(dao)80~100次(ci)/只(材(cai)質為3Cr2W8V).
另外,穿(chuan)(chuan)孔(kong)(kong)(kong)頭(tou)(tou)工(gong)作表面的(de)不(bu)均(jun)勻磨損(sun),將引起(qi)穿(chuan)(chuan)孔(kong)(kong)(kong)后空(kong)心坯的(de)壁(bi)厚不(bu)均(jun)。穿(chuan)(chuan)孔(kong)(kong)(kong)時,將穿(chuan)(chuan)孔(kong)(kong)(kong)頭(tou)(tou)輪流安裝在穿(chuan)(chuan)孔(kong)(kong)(kong)桿上,由10~15穿(chuan)(chuan)孔(kong)(kong)(kong)頭(tou)(tou)組(zu)成為一組(zu),循(xun)環(huan)輪流使用的(de)效果(guo)最(zui)好(hao)。

圖7-53所示為(wei)立(li)式(shi)穿(chuan)(chuan)孔(kong)(kong)機(ji)的穿(chuan)(chuan)孔(kong)(kong)頭和擴孔(kong)(kong)頭。穿(chuan)(chuan)孔(kong)(kong)頭既可(ke)使(shi)用(yong)有柄的(圖7-53(a)),也可(ke)以(yi)使(shi)用(yong)無柄平端面的(圖7-53(b)).這種(zhong)固(gu)定方法,可(ke)以(yi)允許穿(chuan)(chuan)孔(kong)(kong)頭冷卻,檢查或更(geng)換,不占穿(chuan)(chuan)孔(kong)(kong)的周期時間。
穿孔(kong)頭與穿孔(kong)坯料的(de)接觸(chu)端面(mian)被做成帶有圓弧(hu)半徑的(de)凹(ao)面(mian),是(shi)為了保(bao)證在整(zheng)個穿孔(kong)周期(qi)中,玻(bo)璃滑劑能夠均(jun)勻地進入變(bian)形區。
b. 穿孔頭和擴(kuo)孔頭的(de)設計(ji)
穿孔(kong)(kong)(kong)頭(tou)和(he)擴孔(kong)(kong)(kong)頭(tou)的(de)設計數據(ju)(ju)來自于多年(nian)的(de)實際技術工(gong)作經驗數據(ju)(ju)。穿孔(kong)(kong)(kong)頭(tou)(圖(tu)7-54)和(he)擴孔(kong)(kong)(kong)頭(tou)(圖(tu)7-55)定徑帶的(de)直徑,要根(gen)據(ju)(ju)產品的(de)規(gui)格而(er)定。由于穿孔(kong)(kong)(kong)頭(tou)和(he)擴孔(kong)(kong)(kong)頭(tou)在穿(擴)孔(kong)(kong)(kong)過程中直接與(yu)變形金(jin)屬接觸,因(yin)此,其表面(mian)光潔度應(ying)(ying)達(da)到7~8級,且倒角(jiao)要圓(yuan)滑(hua)。穿孔(kong)(kong)(kong)頭(tou)下端的(de)倒角(jiao)半徑R應(ying)(ying)約(yue)為穿孔(kong)(kong)(kong)頭(tou)直徑的(de)10%~20%。

穿孔頭(tou)(tou)上端過渡段的角(jiao)度(du)不宜過大,以防(fang)止(zhi)穿孔頭(tou)(tou)回程(cheng)時刮(gua)傷空心坯的內(nei)表面(mian),其(qi)角(jiao)度(du)一般為5°~25°.穿孔筒和穿孔頭(tou)(tou)較小時,采用較小值。
擴(kuo)孔頭的(de)下錐頭直徑應等于坯料預鉆孔的(de)直徑。
擴孔頭的成形(xing)錐角一般(ban)為30°~60°,太大(da)時擴孔坯(pi)的內壁容易刮傷,且擴孔開始(shi)時導向不(bu)好(hao)。其過(guo)渡段要平滑,以便使金(jin)屬(shu)流動(dong)均勻。
一(yi)般(ban)穿(chuan)孔頭的直徑要比穿(chuan)孔桿的直徑大10~30mm,但(dan)是有時考慮到穿(chuan)孔桿的共用性,而擴大這一(yi)數(shu)值的范圍。
在穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)過程中,穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)頭嚴酷的(de)(de)工作(zuo)條件,往往會使(shi)其(qi)工作(zuo)帶(dai)和沿外(wai)徑(jing)的(de)(de)棱緣(yuan),即側面連接端面的(de)(de)圓角半(ban)徑(jing)處,承(cheng)受(shou)最大的(de)(de)加熱和磨(mo)(mo)損。棱緣(yuan)的(de)(de)磨(mo)(mo)損引起(qi)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)后(hou)空心坯(pi)的(de)(de)壁厚不(bu)均(jun),導(dao)致擠壓鋼管的(de)(de)壁厚不(bu)均(jun)。為了(le)消除穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)頭的(de)(de)不(bu)均(jun)勻磨(mo)(mo)損,避免(mian)因(yin)此而(er)引起(qi)的(de)(de)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)空心坯(pi)的(de)(de)壁厚不(bu)均(jun),在現(xian)代的(de)(de)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)機上采用了(le)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)桿和穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)芯棒運動的(de)(de)套管系統(tong),即在坯(pi)料經鐓(dui)粗(cu)后(hou)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)桿不(bu)立即返回,而(er)是繼(ji)續壓在坯(pi)料上,這樣(yang)可以(yi)使(shi)穿孔(kong)(kong)(kong)(kong)(kong)(kong)(kong)頭精確地對準坯(pi)料的(de)(de)中心,并且減小了(le)其(qi)自由(you)長度。
采(cai)用(yong)帶(dai)圓(yuan)弧半(ban)徑(jing)(jing)的(de)凹面穿(chuan)孔(kong)(kong)頭穿(chuan)孔(kong)(kong),實現了(le)穿(chuan)孔(kong)(kong)桿和穿(chuan)孔(kong)(kong)頭對穿(chuan)孔(kong)(kong)坯料的(de)附(fu)加定心,提高了(le)穿(chuan)孔(kong)(kong)后(hou)(hou)空心坯的(de)壁厚均勻度。在穿(chuan)孔(kong)(kong)過程中,穿(chuan)孔(kong)(kong)頭處于(yu)最嚴酷的(de)工作(zuo)條(tiao)件,其工作(zuo)帶(dai)和沿外徑(jing)(jing)的(de)棱緣(yuan),即側面和端面的(de)圓(yuan)角半(ban)徑(jing)(jing),承受最大(da)的(de)加熱和磨(mo)損。觀察(cha)經(jing)多次使用(yong)后(hou)(hou)的(de)穿(chuan)孔(kong)(kong)頭,其棱緣(yuan)的(de)磨(mo)損引(yin)起穿(chuan)孔(kong)(kong)空心坯壁厚不均,當(dang)出現穿(chuan)孔(kong)(kong)頭棱緣(yuan)的(de)單邊(bian)磨(mo)損時,危險性更大(da)。
穿孔(kong)桿,包(bao)括螺紋固定的穿孔(kong)頭在內,具有(you)通過沿軸線(xian)鉆孔(kong)的冷卻水(shui)孔(kong)槽。穿孔(kong)時用(yong)水(shui)冷卻穿孔(kong)桿和(he)穿孔(kong)頭。
采用(yong)組合式的穿(chuan)孔(kong)工模具,允許(xu)用(yong)低(di)合金(jin)鋼(gang)(gang)(gang)制作(zuo)不(bu)受熱的零件,如采用(yong)5CrNiW、50CrVA鋼(gang)(gang)(gang)制造(zao)固(gu)定穿(chuan)孔(kong)桿的夾具,用(yong)5CrNiW、5CrNiMo鋼(gang)(gang)(gang)制造(zao)穿(chuan)孔(kong)桿,用(yong)高(gao)合金(jin)鋼(gang)(gang)(gang)和耐熱合金(jin)鋼(gang)(gang)(gang)制造(zao)穿(chuan)孔(kong)頭。
擴孔(kong)(kong)過程中,擴孔(kong)(kong)頭的(de)錐形(xing)表(biao)面受到最劇烈的(de)磨損(sun),并(bing)逐漸形(xing)成(cheng)劃道和凹(ao)陷。擴孔(kong)(kong)頭的(de)工作負荷較穿(chuan)孔(kong)(kong)頭要輕(qing)許多(duo),因(yin)此其(qi)使用壽命(ming)比穿(chuan)孔(kong)(kong)頭高得多(duo),一(yi)般可達到80~100次。
擴(kuo)孔(kong)頭(tou)(tou)的(de)長度取(qu)決于穿(chuan)孔(kong)機(ji)的(de)結(jie)構形(xing)(xing)式,并且首先取(qu)決于穿(chuan)孔(kong)桿和穿(chuan)孔(kong)筒(tong)上平面(mian)之間的(de)距(ju)離。如果其間隙大,為了(le)減小成形(xing)(xing)角度,擴(kuo)孔(kong)頭(tou)(tou)可(ke)以做得(de)比較長。擴(kuo)孔(kong)頭(tou)(tou)成形(xing)(xing)角的(de)平均(jun)值一般(ban)等于15°~20°,而(er)在最(zui)大的(de)擴(kuo)孔(kong)程度時,可(ke)以達到30°~32°.
穿孔頭和擴孔頭必須具有良好的綜合力學性能,工(gong)作表面光潔圓滑,與(yu)穿孔桿連接可(ke)靠,更(geng)換方便。
穿孔頭的形狀由端面圓角半徑R,工作帶l1和倒錐l2組成(圖7-54).各部分的尺寸,按以下經驗公式確定:

采用(yong)倒錐的(de)目的(de)是(shi)為了(le)防止穿孔(kong)頭回程(cheng)時刮切金屬或帶出空心坯。穿孔(kong)頭端(duan)面(mian)加(jia)工成凹(ao)面(mian)的(de)目的(de),是(shi)為了(le)儲存(cun)潤(run)滑劑,以(yi)使在整個穿孔(kong)過(guo)程(cheng)中,保持潤(run)滑劑的(de)連續供應。
擴孔頭由鼻尖l3、擴孔錐l4、工作帶l5和反向錐l6組成(圖7-55).鼻尖的作用是導向和定心,其直徑等于坯料鉆孔直徑,長度l3約為10~20mm,擴孔錐角α一般取15°~20°,當擴徑量大時,可達30°~32°,工作帶直徑dc由擠壓工藝表得到,其長度l5一般為6~10mm。
由于擴(kuo)孔錐(zhui)至工作帶處的磨損最為(wei)嚴重,故該(gai)處采用圓滑過渡,其(qi)他(ta)尺(chi)寸同上。
c. 剪切環組件
剪(jian)切環組(zu)件包括下支承桿、支承頭、剪(jian)切環和(he)連接件等零部件。
支承(cheng)頭和剪(jian)(jian)切環的作用是在穿(chuan)(chuan)孔過程中封閉(bi)穿(chuan)(chuan)孔筒內襯(chen)的下端面(mian),以減小穿(chuan)(chuan)孔余料的高度,為空心坯(pi)下端面(mian)定形;在穿(chuan)(chuan)孔結束時,剪(jian)(jian)切環還要剪(jian)(jian)斷穿(chuan)(chuan)孔余料;支承(cheng)桿最后將(jiang)穿(chuan)(chuan)孔空心坯(pi)從穿(chuan)(chuan)孔筒內襯(chen)中推出。
在整個穿孔(kong)過程(cheng)中,支承頭(tou)和(he)剪切環的(de)(de)上端面(mian)(mian)和(he)加熱(re)到高(gao)溫的(de)(de)坯料相(xiang)接觸,使其表面(mian)(mian)層金(jin)屬被加熱(re)到650~700℃.使用(yong)過程(cheng)中剪切環的(de)(de)主要破壞形式(shi)是端面(mian)(mian)棱緣翹(qiao)曲和(he)焊(han)瘤(圖2-27).
剪切(qie)環與穿孔(kong)(kong)頭(tou)或擴孔(kong)(kong)頭(tou)之(zhi)間(jian)的間(jian)隙(xi)不能過(guo)大(da),一(yi)般小于2mm.如果此間(jian)隙(xi)過(guo)大(da)或剪切(qie)環過(guo)度磨損,則會導致在(zai)剪切(qie)穿孔(kong)(kong)或擴孔(kong)(kong)余料的過(guo)程中,坯料前端內孔(kong)(kong)處產生飛(fei)邊缺(que)陷(xian),并易引起擠壓筒(tong)和擠壓模的損壞。

