耐磨鋼鑄件冒口的切割很困難,因而不能像一般鑄鋼件那樣使用大冒口改善鑄件的補縮。為此不得不采取各種工藝措施改善耐磨鋼鑄件的補縮條件,如使用發熱劑、絕熱冒口、冒口和冷鐵配合、澆注時補澆冒口等。
耐磨鋼的體收縮雖然是很大(da),且一般也采(cai)用加冒口的方法(fa)進行補(bu)縮。
不使(shi)(shi)用(yong)冒(mao)口(kou)并(bing)不是(shi)不出現體收(shou)縮(suo),只是(shi)均(jun)勻壁厚的(de)(de)(de)鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)體收(shou)縮(suo),當(dang)(dang)工(gong)藝(yi)控(kong)(kong)制得(de)當(dang)(dang)時(shi)(shi),可(ke)以(yi)不呈縮(suo)孔的(de)(de)(de)形(xing)式而(er)以(yi)軸(zhou)線(xian)(xian)疏(shu)松(song)的(de)(de)(de)形(xing)式出現。當(dang)(dang)壁厚減(jian)薄到(dao)(dao)(dao)一定程度時(shi)(shi),無論(lun)是(shi)達(da)(da)到(dao)(dao)(dao)疏(shu)松(song)帶(dai)或尚(shang)未達(da)(da)到(dao)(dao)(dao)疏(shu)松(song)帶(dai).易損件(jian)(jian)(jian)(jian)(jian)即需更換(huan)(huan)。因此即使(shi)(shi)存在軸(zhou)線(xian)(xian)疏(shu)松(song)也不影響鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)使(shi)(shi)用(yong)。使(shi)(shi)用(yong)無冒(mao)口(kou)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)工(gong)藝(yi)的(de)(de)(de)條件(jian)(jian)(jian)(jian)(jian)之一是(shi),鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian)斷面(mian)必須均(jun)勻、無熱節,如桿形(xing)件(jian)(jian)(jian)(jian)(jian)、板(ban)(ban)形(xing)件(jian)(jian)(jian)(jian)(jian)等(deng)。其(qi)次是(shi)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)工(gong)藝(yi)要控(kong)(kong)制得(de)當(dang)(dang),使(shi)(shi)鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian)進行(xing)同(tong)時(shi)(shi)凝固(gu)。澆注(zhu)(zhu)系(xi)統(tong)的(de)(de)(de)設(she)置應(ying)使(shi)(shi)金屬分散引人型(xing)腔,不使(shi)(shi)金屬引入處成為(wei)熱節。使(shi)(shi)用(yong)無冒(mao)口(kou)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)時(shi)(shi)應(ying)盡量降低(di)(di)澆注(zhu)(zhu)溫度。澆注(zhu)(zhu)溫度愈低(di)(di),型(xing)腔中鋼水(shui)的(de)(de)(de)平(ping)均(jun)溫度愈低(di)(di),液(ye)態下體收(shou)縮(suo)可(ke)以(yi)減(jian)少。無冒(mao)口(kou)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)時(shi)(shi)型(xing)腔排氣(qi)較困(kun)難,鑄(zhu)(zhu)(zhu)(zhu)(zhu)型(xing)工(gong)藝(yi)方面(mian)應(ying)加(jia)強排氣(qi)措施。做到(dao)(dao)(dao)以(yi)上各點,無冒(mao)口(kou)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)是(shi)可(ke)行(xing)的(de)(de)(de),在生產中這(zhe)種(zhong)方法(fa)也得(de)到(dao)(dao)(dao)了廣泛(fan)的(de)(de)(de)使(shi)(shi)用(yong)。例(li)如球磨(mo)(mo)機的(de)(de)(de)襯(chen)板(ban)(ban)、反擊式破(po)碎機的(de)(de)(de)板(ban)(ban)錘等(deng)鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian),均(jun)屬于這(zhe)類情況。反擊式破(po)碎機板(ban)(ban)錘是(shi)一個斷面(mian)均(jun)勻的(de)(de)(de)長條形(xing)鑄(zhu)(zhu)(zhu)(zhu)(zhu)件(jian)(jian)(jian)(jian)(jian)。使(shi)(shi)用(yong)中當(dang)(dang)一邊磨(mo)(mo)損到(dao)(dao)(dao)一定程度時(shi)(shi),調換(huan)(huan)方向使(shi)(shi)用(yong),第(di)二邊磨(mo)(mo)損后更換(huan)(huan)新的(de)(de)(de)備件(jian)(jian)(jian)(jian)(jian),中心軸(zhou)線(xian)(xian)疏(shu)松(song)帶(dai)始終不致(zhi)暴露出來,因而(er)可(ke)用(yong)無冒(mao)口(kou)鑄(zhu)(zhu)(zhu)(zhu)(zhu)造(zao)工(gong)藝(yi)。
在使(shi)用(yong)有冒(mao)口來進行補縮時(shi),為了減少(shao)不必要的(de)(de)(de)浪(lang)費以(yi)及(ji)減輕冒(mao)口的(de)(de)(de)去(qu)除和(he)(he)減少(shao)機械加工的(de)(de)(de)工作(zuo)量,耐(nai)(nai)磨鋼鑄件(jian)常采用(yong)細頸冒(mao)口和(he)(he)易(yi)割冒(mao)口。易(yi)割冒(mao)口僅通過易(yi)割片上的(de)(de)(de)孔使(shi)冒(mao)口和(he)(he)鑄件(jian)相連(lian)并進行補縮。冒(mao)口截面上的(de)(de)(de)其余部(bu)(bu)分和(he)(he)鑄件(jian)的(de)(de)(de)本體之間(jian)則被(bei)耐(nai)(nai)火材料(liao)制成(cheng)的(de)(de)(de)易(yi)割片分開。它是(shi)由耐(nai)(nai)火材料(liao)燒(shao)制而成(cheng),有較(jiao)高的(de)(de)(de)強度(du),也可以(yi)用(yong)強度(du)高的(de)(de)(de)芯砂制作(zuo)。用(yong)耐(nai)(nai)火材料(liao)燒(shao)制者(zhe)厚度(du)可小些。易(yi)割冒(mao)口可以(yi)有各種(zhong)(zhong)類型(xing),可以(yi)是(shi)頂冒(mao)口,從(cong)頂部(bu)(bu)補縮;也可以(yi)作(zuo)成(cheng)側冒(mao)口。各種(zhong)(zhong)類型(xing)的(de)(de)(de)易(yi)割冒(mao)口的(de)(de)(de)形(xing)式和(he)(he)有關參(can)數見表3- I0。由于易(yi)割片的(de)(de)(de)厚度(du)很小,很快就(jiu)會被(bei)澆人鑄型(xing)的(de)(de)(de)鋼水(shui)加熱到鋼水(shui)的(de)(de)(de)溫度(du)。
但是(shi)由(you)于(yu)耐火材(cai)料吸收一部分(fen)熱(re)量(liang),畢(bi)竟影響(xiang)冒(mao)(mao)口(kou)中金屬的補縮效(xiao)果,因(yin)此(ci)(ci)(ci)易(yi)(yi)割(ge)(ge)冒(mao)(mao)口(kou)較相(xiang)同條件的普通冒(mao)(mao)口(kou)的尺寸(cun)要(yao)稍大些(可增(zeng)大10%一1596 )。易(yi)(yi)割(ge)(ge)冒(mao)(mao)口(kou)由(you)于(yu)補縮孔(kong)處金屬溫度最高,此(ci)(ci)(ci)處易(yi)(yi)產生疏松(song),因(yin)此(ci)(ci)(ci)使用(yong)此(ci)(ci)(ci)種冒(mao)(mao)口(kou)時要(yao)當心。有些均勻壁(bi)厚的中、小(xiao)型(xing)耐磨(mo)鋼件可以使用(yong)無冒(mao)(mao)口(kou)的鑄(zhu)造(zao)工(gong)藝。這可以節約冒(mao)(mao)口(kou)金屬,更重(zhong)要(yao)的是(shi)簡化了鑄(zhu)造(zao)工(gong)藝,尤(you)其是(shi)減少(shao)了切割(ge)(ge)冒(mao)(mao)口(kou)的工(gong)序。
耐磨鋼|耐磨鋼板|高強度鋼板| 高強鋼現貨——法鋼特(te)種(zhong)鋼材(cai)(上(shang)海)有(you)限公司
