Kumanga kwa Shell kwa Investment Casting

Kuponyera ndalama ndikukuta zigawo zingapo za zokutira zomangira pamwamba pa nkhungu ya sera. Akaumitsa ndi kuumitsa, nkhungu ya sera imasungunuka ndi kutentha kuti ipeze chigoba chokhala ndi bowo lolingana ndi mawonekedwe a sera. Pambuyo kuphika, amatsanuliridwa mu Njira yopezera zoponyera, motero amatchedwanso kutaya sera. Ndi kuwongolera kosalekeza kwaukadaulo wopanga, njira zatsopano zopangira sera zikupitilizabe kuwoneka, ndipo mitundu yosiyanasiyana ya zida zomwe zilipo pakuumba zikuchulukirachulukira. Tsopano njira kuchotsa nkhungu salinso okha kusungunuka, ndi akamaumba zipangizo si zokhazo zipangizo sera. Amaumba apulasitiki angagwiritsidwenso ntchito. Chifukwa ma castings omwe amapezedwa ndi njirayi amakhala olondola kwambiri komanso otsika kwambiri, amatchedwanso kuponya kolondola.

Zofunika mbali yakuponya ndalaman'chakuti nkhungu yomwe imatha kusungunuka imagwiritsidwa ntchito popanga chipolopolocho. Chifukwa palibe chifukwa chojambulira nkhungu, chipolopolocho ndi chofunikira popanda malo olekanitsa, ndipo chipolopolocho chimapangidwa ndi zinthu zotsutsana ndi kutentha kwakukulu. Investment kuponyera akhoza kupanga castings zovuta woboola pakati, ndi osachepera khoma makulidwe a 0.3mm ndi awiri osachepera a bowo kuponyera 0,5 mm. Nthawi zina popanga, magawo ena opangidwa ndi magawo angapo amatha kuphatikizidwa pamodzi posintha kapangidwe kake ndikupangidwa mwachindunji ndi kuponya ndalama. Izi akhoza kupulumutsa processing munthu-maola ndi mowa zinthu zitsulo, ndi kupanga dongosolo lakuponya ziwalozololera.

Kulemera kwa ma castings opangidwa ndi kuponya ndalama nthawi zambiri kumayambira makumi a magalamu mpaka ma kilogalamu angapo, kapena ma kilogalamu khumi. Kuponyedwa kolemetsa kwambiri sikuli koyenera kuponya ndalama chifukwa cha kuchepa kwa ntchito ya zinthu zomangira komanso zovuta kupanga chipolopolo.

Ma castings opangidwa ndi Investment castingsizimangokhala ndi mitundu ya aloyi, makamaka kwa alloys omwe ndi ovuta kudula kapena kupanga, omwe angasonyeze kupambana kwake. Komabe, kupanga ndalama zopangira ndalama kumakhalanso ndi zofooka zina, makamaka chifukwa cha kuchuluka kwa njira, nthawi yayitali yopanga, njira zaukadaulo zovuta, ndi zinthu zambiri zomwe zimakhudza mtundu wa castings, zomwe ziyenera kuyendetsedwa mosamalitsa kuti zikhazikike.

Poyerekeza ndi njira zina zoponyera, chochititsa chidwi kwambiri pakupanga ndalama ndikugwiritsira ntchito nkhungu zosungunuka kupanga chipolopolo. Chikombole chimodzi cha ndalama chimadyedwa nthawi iliyonse chipolopolo chimapangidwa. Chofunikira kuti mupeze ma castings apamwamba kwambiri olondola kwambiri komanso otsika kwambiri amtundu wapamtunda ndi nkhungu yandalama yomwe imakhala yolondola kwambiri komanso yotsika kwambiri. Chifukwa chake, magwiridwe antchito a zinthu zomangira (zomwe zimatchedwa nkhungu), mtundu wa mawonekedwe (chitsanzo chomwe chimagwiritsidwa ntchito kukakamiza ndalama) ndi njira yopangira zinthuzo zimakhudza mwachindunji kuyika kwa ndalama.

Zopangira ndalama zopangira ndalama zimagwiritsidwa ntchito pazigoba zopangidwa ndi multilayer refractory materials. Pambuyo choviikidwa ndi yokutidwa ndi ❖ kuyanika refractory, kuwaza granular refractory zakuthupi, ndiyeno youma ndi kuumitsa, ndi kubwereza ndondomekoyi nthawi zambiri mpaka wosanjikiza refractory kufika makulidwe chofunika. Mwanjira iyi, chipolopolo chamitundu yambiri chimapangidwa pa module, yomwe nthawi zambiri imayimitsidwa kwa nthawi kuti iume bwino ndikuumitsa, kenako ndikugwetsedwa kuti ipeze chipolopolo chamitundu yambiri. Zipolopolo zina zamitundu yambiri zimafunika kudzazidwa ndi mchenga, ndipo zina sizitero. Pambuyo pakuwotcha, amatha kutsanuliridwa mwachindunji, chomwe chimatchedwa chipolopolo champhamvu kwambiri.

Ubwino wa chipolopolo umagwirizana mwachindunji ndi khalidwe la kuponyera. Malinga ndi momwe chipolopolocho chimagwirira ntchito, zofunikira za chipolopolocho zimaphatikizirapo:
1) Ili ndi mphamvu yotentha yanthawi zonse, mphamvu yoyenera kutentha komanso mphamvu yotsalira yotsika.
2) Ili ndi mpweya wabwino (makamaka kutentha kwa mpweya wabwino) komanso kutentha kwa kutentha.
3) Mzere wowonjezera wowonjezera ndi wochepa, kuwonjezereka kwa kutentha kumakhala kochepa ndipo kufalikira kuli kofanana.
4) Kukana kwabwino kwa kuzizira kofulumira komanso kutentha komanso kukhazikika kwa thermochemical.

Zinthu za chipolopolozi zimagwirizana kwambiri ndi zinthu zomwe zimagwiritsidwa ntchito popanga zipolopolo komanso kupanga zipolopolo. Zida za zipolopolo zimaphatikizapo zipangizo zotsutsa, zomangira, zosungunulira, zowumitsa, zowonjezera, ndi zina zotero. Pakati pawo, zinthu zowonongeka ndi zomangira zimapanga chipolopolocho, chomwe ndi chipolopolo chachikulu. The refractory zipangizo ntchito poponya ndalama makamaka silika mchenga, corundum ndi aluminosilicate refractories (monga dongo refractory ndi aluminium banadium, etc.). Kuphatikiza apo, mchenga wa zircon ndi mchenga wa magnesia nthawi zina amagwiritsidwa ntchito.

Zopangira ufa zaufa ndi zomangira zimakonzedwa kuti zikhale zokutira, ndipo zinthu zokanira granular zimakonkhedwa pa zokutira zomangira chipolopolocho chikapangidwa. Zomangira zomwe zimagwiritsidwa ntchito popaka zokutira makamaka zimaphatikizapo ethyl silicate hydrolysate, galasi lamadzi ndi silica sol. Utoto wokonzedwa ndi ethyl silicate uli ndi zida zabwino zokutira, kulimba kwa chipolopolo champhamvu, kapindika kakang'ono ka matenthedwe, kulondola kwapamwamba kwazomwe zapezedwa, komanso mawonekedwe abwino apamwamba. Amagwiritsidwa ntchito kwambiri popanga ma castings ofunikira azitsulo zachitsulo ndi ma castings ena okhala ndi zofunikira zapamwamba kwambiri. SiO2 yomwe ili mu ethyl silicate yopangidwa ku China nthawi zambiri imakhala 30% mpaka 34% (chigawo cha misa), kotero imatchedwa ethyl silicate 32 (32 imayimira gawo lalikulu la SiO2 mu ethyl silicate). Ethyl silicate imatha kugwira ntchito yomangiriza pokhapokha hydrolysis.

Chigoba chophimba chokonzedwa ndi galasi lamadzi ndi chosavuta kupunduka ndi kusweka. Poyerekeza ndi ethyl silicate, ma castings opangidwa amakhala olondola pang'ono komanso olimba kwambiri. Madzi galasi binder ndi oyenera kupanga yaing'ono wamba zitsulo castings ndizopanda ferrous alloy castings. Magalasi amadzi opangira ndalama nthawi zambiri amakhala ndi modulus ya 3.0 ~ 3.4 ndi kachulukidwe ka 1.27 ~ 1.34 g/cm3.

Silica sol binder ndi yankho lamadzi la silicic acid, lomwe limadziwikanso kuti silica sol. Mtengo wake ndi 1/3 ~ 1/2 wotsika kuposa wa ethyl silicate. Ubwino wa ma castings opangidwa pogwiritsa ntchito silica sol ngati binder ndi wapamwamba kuposa wa galasi lamadzi. Womangiriza adawongoleredwa kwambiri. Silika sol imakhala yokhazikika bwino ndipo imatha kusungidwa kwa nthawi yayitali. Sichifuna zowumitsa zapadera popanga zipolopolo. Kutentha kwamphamvu kwa chipolopolocho ndikwabwino kuposa kwa zipolopolo za ethyl silicate, koma silika sol imakhala ndi kunyowa kwachuma ndipo imatenga nthawi yayitali kuti iwumitse. Njira zazikuluzikulu zopangira zipolopolo zimaphatikizapo kuchotsera mafuta, kupaka ndi mchenga, kuyanika ndi kuumitsa, kudula ndi kuwotcha.