Lub smelting thiab pouring ntawm alloys yog cov txheej txheem tseem ceeb hauv casting ntau lawm. Kev tswj xyuas tag nrho cov smelting thiab pouring txheej txheem plays lub luag haujlwm tseem ceeb hauv kev tiv thaiv qhov tsis xws luag xws li pinholes, inclusions, misruns, tawg, porosity, thiab shrinkage.
Txij li thaum molten aluminium muaj ib tug muaj zog nyiam nqus hydrogen, muaj zog oxidizing zog, thiab yooj yim dissolves hlau, yooj yim tab sis ceev faj yuav tsum tau noj thaum lub sij hawm melting thiab casting txheej txheem los tsim high{0}} zoo castings.
1. Txias ntawm Aluminium Alloy Rauv Cov Khoom Siv thiab Kev Tswj Xyuas Zoo
Yuav kom ua tau zoo - zoo molten aluminium, tsim nyog raw cov ntaub ntawv yuav tsum tau xaiv ua ntej. Cov ntaub ntawv raw yuav tsum raug tswj xyuas thiab kho kom raug; txwv tsis pub, qhov zoo ntawm cov alloy yuav raug cuam tshuam loj heev. Kev xyaum ua ntau lawm tau pom tias yog cov khoom siv raw (xws li cov khoom siv hlau thiab cov khoom siv pabcuam) tsis raug tswj nruj, cov khoom ntawm cov castings yuav raug muab pov tseg.
(1) Cov khoom siv raw yuav tsum muaj cov tshuaj lom neeg tsim nyog thiab cov qauv, nrog rau cov kev cai tshwj xeeb raws li hauv qab no:
Ntxiv nrog rau kev txheeb xyuas cov khoom tseem ceeb thiab cov ntsiab lus tsis huv ntawm cov khoom siv hlau nkag mus rau hauv lub Hoobkas, kev tshuaj xyuas kuj tau ua rau qis-cov qauv alloy thiab cov pob txha tawg. Kev xyaum tau ua pov thawj tias kev siv cov txhuas yaj uas muaj cov kab noj hniav loj, cov pinholes, thiab npuas ua rau nws nyuaj kom tau txais cov castings ntom ntom thiab tuaj yeem ua rau lub qhov cub tawg tag nrho los yog batch ntawm castings.
Thaum kawm txog cov nyhuv ntawm aluminium-silicon alloy ingots ntawm aluminium alloy porosity, nws tau pom tias tsis muaj qhov porosity tshwm sim thaum siv cov kev sim blocks ua los ntawm cov xuab zeb dawb huv molten - nrum pwm. Txawm li cas los xij, tom qab ntxiv qis - zoo thiab tsis zoo txhuas- silicon alloy ingots, cov kev sim ntsuas tau pom qhov porosity hnyav thiab cov nplej ntxhib. Yog vim li cas rau qhov no yog vim cov khoom siv qub txeeg qub teg. Rau aluminium-silicon alloys, cov nyhuv qub txeeg qub teg nce nrog cov ntsiab lus, ua qhov tseem ceeb thaum cov ntsiab lus silicon nce mus txog 7%. Txuas ntxiv mus ntxiv cov ntsiab lus ntawm silicon rau eutectic muaj pes tsawg leeg yuav txo tau cov txiaj ntsig qub txeeg qub teg. Txhawm rau daws qhov tsis xws luag los ntawm cov txiaj ntsig qub txeeg qub teg ntawm cov khoom siv hluav taws xob, nws yog ib qho tsim nyog yuav tsum xaiv cov khoom siv hlau zoo aluminium ingots, intermediate alloys, thiab lwm yam khoom siv hluav taws xob. Cov qauv tshwj xeeb yog raws li hauv qab no:
1) Cov pob txha tawg yuav tsum tsis txhob muaj pinholes lossis lub qhov roj
Pinholes yuav tsum nyob rau qib peb, thiab hauv zos (tsis pub ntau tshaj 25% ntawm thaj chaw kuaj xyuas) yuav tsum tsis pub tshaj qib peb. Yog tias nws dhau qib peb, remelting yuav tsum tau ua kom txo qis qib pinhole. Cov txheej txheem remelting thiab refining yog tib yam li cov txhuas alloy melting. Qhov kub ntawm casting yuav tsum tsis pub tshaj 660 degree. Rau aluminium ingots los yog alloy ingots nrog loj thawj nplej, ib tug qis pwm kub yuav tsum tau siv ua ntej kom lawv solidify sai thiab refine cov nplej.
(2) Them khoom tuav
Ua ntej siv, cov ntaub ntawv them nqi yuav tsum tau sandblasted kom tshem tawm cov xeb, roj, thiab lwm yam kab mob. Aluminium alloy ingots thiab metallic scraps nrog ib tug kuj huv si nto thiab lub sij hawm cia luv luv yuav tsis xav tau sandblasting, tab sis tej yam hlau lim los yog embedded Cheebtsam sib tov nyob rau hauv tus nqi yuav tsum tau muab tshem tawm. Tag nrho cov ntaub ntawv them nqi yuav tsum tau preheated ua ntej muab tso rau hauv lub cub tawg kom tshem tawm cov av noo thiab txo lub sij hawm melting ntau tshaj 3 teev.
(3) Kev tswj thiab khaws cov khoom siv rauv taws
Kev khaws cia kom zoo thiab kev tswj cov khoom siv rau cov khoom siv hluav taws xob yog qhov tseem ceeb rau kev ua kom zoo ntawm cov alloys. Cov khoom siv rauv yuav tsum muab khaws cia rau hauv cov tsev khaws khoom uas muaj qhov sib txawv me ntsis ntawm qhov kub thiab txias.
2. Kev npaj Crucibles thiab Smelting cuab yeej
(1) Rau casting aluminium alloy, ntau cov hlau crucibles yog siv, thiab crucibles ua los ntawm cam khwb cia hlau los yog welded steel daim hlau kuj siv tau.
Ob lub crucibles tshiab thiab qub crucibles uas tsis tau siv rau lub sij hawm ntev yuav tsum tau sandblasted ua ntej siv thiab rhuab mus rau 700-800 degree, tuav no kub rau 2-4 teev kom hlawv tawm ya raws thiab combustible tshuaj adhering rau lub puab phab ntsa ntawm lub crucible. Thaum txias kom qis dua 300 degree, ua tib zoo ntxuav cov phab ntsa sab hauv ntawm lub crucible, thiab siv cov txheej thaum kub tsis qis dua 200 degree.
Lub crucible yuav tsum tau preheated rau ib tug tsaus liab xim (500-600 degree) ua ntej siv thiab khaws cia nyob rau hauv qhov kub thiab txias rau ntau tshaj 2 teev. Rau lub crucible tshiab, nws yog qhov zoo tshaj plaws los ua ntej yaj ib pawg ntawm cov khoom siv rov ua dua tshiab ntawm tib qib ua ntej smelting cov khoom siv tiag tiag.
(2) Kev npaj cov cuab yeej smelting
Tswb npog, smashing hau, stirring diav, ncuav lub hnab
Ua ntej siv, pwm thiab lwm yam khoom siv yuav tsum tau preheated, coated nrog ib tug tiv thaiv txheej ntawm ib tug kub ntawm 150-200 degree, thiab kom qhuav. Qhov kub kom qhuav yuav tsum yog 200-400 degree, nrog lub sijhawm tuav ntau tshaj 2 teev. Tom qab siv, txhua oxides thiab fluorides adhering rau saum npoo yuav tsum raug tshem tawm tag nrho (sandblasting yog pom zoo).
3. Kev tswj qhov kub thiab txias
Yog hais tias lub melting kub yog tsawg heev, nws tsis yog conducive rau lub dissolution ntawm alloying ntsiab thiab tshem tawm cov gases thiab inclusions, ua rau kom muaj kev sib cais, txias shuts, thiab misruns. Nws kuj tuaj yeem ua rau tsis txaus cua sov hauv cov riser, tiv thaiv kev pub mis kom zoo ntawm cov casting. Raws li qee cov ntaub ntawv, qhov kub ntawm tag nrho cov txhuas alloys yuav tsum ncav cuag tsawg kawg 705℃thiab stirring yuav tsum tau ua. Ntawm qhov tod tes, qhov kub melting ntau dhau tsis tsuas yog khib nyiab lub zog tab sis, qhov tseem ceeb tshaj, ua rau muaj kev nqus hydrogen ntxiv, coarser nplej, ntau dua aluminium oxidation, thiab ntau dua qhov poob ntawm qee cov ntsiab lus alloying. Yog li ntawd, cov khoom siv ntawm cov hlau tsis zoo, casting thiab machining kev ua tau zoo zuj zus, qhov ua tau zoo ntawm kev kho cua sov yog txo, thiab cov roj- nruj ntawm cov casting txo.
Kev xyaum ntau lawm tau ua pov thawj tias cov cua sov sai sai rau qhov kub thiab txias thiab ua kom zoo stirring pab yaj tag nrho cov ntsiab lus alloying (tshwj xeeb tshaj yog cov hlau refractory). Tom qab tshem tawm cov floating slag, txo qhov kub thiab txias mus rau lub pouring point minimizes segregation, txo cov hydrogen yaj, thiab pab kom tau ib tug uniform, ntom alloy nrog high mechanical zog. Txij li thaum qhov kub ntawm cov txhuas yaj yog qhov nyuaj rau txiav txim nrog lub qhov muag liab qab, txawm tias hom melting rauv siv, qhov kub thiab txias yuav tsum tau tswj nrog lub ntsuas ntsuas. Cov cuab yeej ntsuas yuav tsum tsis tu ncua calibrated thiab khaws cia. Lub tes tsho thermocouple yuav tsum tau ntxuav ib ntus nrog txhuam txhuam thiab coated nrog cov xim tiv thaiv kom ntseeg tau tias qhov ntsuas kub zoo thiab kev ua haujlwm ntev.
4. Tswj lub sij hawm melting
Txhawm rau txo cov oxidation ntawm aluminium yaj, nqus cov pa, thiab tawg ntawm cov hlau, lub sij hawm nyob ntawm txhuas yaj hauv lub cub tawg yuav tsum raug txo kom tsawg, thiab melting yuav tsum tau nqa tawm sai. Txij thaum pib melting mus rau qhov ua tiav ntawm pouring, lub sij hawm yuav tsum tsis txhob ntau tshaj 4 teev rau xuab zeb casting, 6 teev rau hlau pwm casting, thiab 8 teev rau tuag casting.
Txhawm rau ua kom cov txheej txheem melting, qhov nruab nrab - qhov loj me nrog qhov qis melting point thiab aluminium -silicon intermediate alloys yuav tsum tau ntxiv ua ntej, kom lub pas dej yaj sai sai rau hauv qab ntawm lub crucible. Tom qab ntawd, cov khoom loj dua ntawm cov khoom seem thiab cov ntshiab aluminium ingots raug ntxiv, tso cai rau lawv maj mam nkag mus rau hauv lub pas dej uas nthuav dav thiab yaj sai. Tom qab qhov tseem ceeb ntawm cov nqi tau yaj lawm, ib qho me me ntawm ntau dua - melting intermediate alloys ntxiv, thiab qhov kub thiab txias tau nce thiab nplawm kom nrawm melting. Thaum kawg, qhov ntsuas kub qis dua thiab yooj yim oxidized alloying ntsiab yog nias rau hauv kom txo qis.
5. Hloov thiab Pouring ntawm Melt
Txawm hais tias qhov ntom ntawm cov khoom alumina yog kwv yees li sib npaug ntawm cov molten aluminium, thaum nws nkag mus rau hauv cov txhuas yaj, nws yuav siv sij hawm ntev txaus los khom rau hauv qab ntawm lub crucible. Nyob rau hauv sib piv, cov alumina zaj duab xis tsim nyob rau saum npoo ntawm txhuas tom qab oxidation muaj ib tug ntom sab nyob rau hauv kev sib cuag nrog cov txhuas yaj, thaum lub sab raug rau huab cua yog xoob thiab muaj ntau pores nrog diameters ntawm 60-100 Å. Cov yeeb yaj kiab no muaj thaj tsam loj thiab muaj zog adsorption zog, uas ua rau nws yooj yim adsorb dej vapor thiab txawm zoo li ntab. Yog li ntawd, txij li qhov sib txawv ntawm qhov sib txawv ntawm cov oxide zaj duab xis thiab cov txhuas yaj yog me me, sib xyaw rau hauv cov yaj ua rau qeeb qeeb thiab ntab, ua rau nws nyuaj rau tshem tawm ntawm cov yaj, thiab ua rau cov roj pores thiab cov khoom siv hauv cov castings. Yog li ntawd, thaum hloov cov txhuas melts, nws yog ib qho tseem ceeb kom txo tau qhov sib tov ntawm cov hlau molten thiab txo cov yaj qhov raug cua kom ntau li ntau tau.
Thaum siv lub tilting crucible rau ncuav molten hlau, kom tsis txhob sib tov cov hlau molten nrog cua, lub ladle yuav tsum tau muab tso rau ze li ntawm lub cub tawg spout li sai tau thiab tilted kom cov hlau molten ntws nyob rau sab phab ntsa ntawm lub ladle, tiv thaiv nws los ntawm ncaj qha mus ntaus hauv qab ntawm lub ladle, uas yuav ua rau agitation los yog splashing.
Kev siv cov txheej txheem pouring kom raug thiab tsim nyog yog ib qho tseem ceeb rau kev tau txais cov khoom zoo siab - castings. Kev xyaum ntau lawm qhia tau hais tias kev saib xyuas cov ntsiab lus hauv qab no zoo heev los tiv thaiv thiab txo qhov tsis xws luag casting.
(1) Ua ntej pouring, ua tib zoo xyuas lub cub tawg kub, lub peev xwm pouring ladle, thiab dryness ntawm txheej txheej ntawm nws nto, thiab seb puas muaj lwm yam cuab yeej npaj txaus. Cov hlau pouring khob yuav tsum muab tso rau ntawm cov xuab zeb pwm 3-5 feeb ua ntej pouring. Thaum lub sij hawm no, qhov kub ntawm lub pouring ladle yuav tsum tsis txhob ntau tshaj 150 degree. Yog tias muab tso rau ntxov dhau los yog qhov kub thiab txias dhau lawm, cov pa roj ntau tuaj yeem sib sau ua ke hauv cov dej ntws, ua rau muaj kev pheej hmoo ntawm kev tawg thaum lub sij hawm nchuav.
(2) Pouring yuav tsum tsis txhob ua nyob rau hauv qhov chaw nrog cov ntawv sau, qhov twg cov hlau molten yuav ua rau oxidize los yog hlawv, uas yuav ua rau oxidation inclusions thiab lwm yam tsis xws luag nyob rau hauv lub casting.
(3) Thaum tau txais molten hlau los ntawm lub crucible, ua ntej maj mam tshem tawm cov oxide zaj duab xis los yog flux txheej nyob rau saum npoo ntawm cov yaj nrog rau hauv qab ntawm lub ladle, ces maj mam muab tso rau hauv lub ladle rau hauv lub molten hlau, nplawm lub yaj nrog lub qhov ncauj dav ntawm lub ladle, thiab nqa lub ladle tsis tu ncua.
(4) Thaum nqa lub ladle, tsis txhob tig nws nrog koj xib teg; taug kev tsis tu ncua. Lub ladle yuav tsum tsis txhob nqa siab dhau, thiab qib hlau sab hauv yuav tsum nyob ruaj khov thiab tsis muaj kev cuam tshuam.
(5) Ua ntej pouring, tshem tawm cov slag los ntawm lub ladle kom tsis txhob nqa slag, oxide zaj duab xis, thiab lwm yam impurities rau hauv pwm thaum lub sij hawm pouring.
(6) Thaum lub sij hawm nchuav, xyuas kom meej tias qhov ntws ntawm cov hlau molten tseem ruaj khov; nws yuav tsum tsis txhob cuam tshuam los yog coj mus rau hauv qab ntawm sprue ncaj qha. Lub sprue yuav tsum tau sau los ntawm sab saum toj mus rau hauv qab, thiab cov kua nto yuav tsum nyob twj ywm. Tswj lub pouring ceev kom tsim nyog. Feem ntau, pib pouring qeeb qeeb me ntsis kom cov yaj mus sau tusyees, ces nce qhov ceev me ntsis thiab tuav tus nqi sib npaug sib npaug.
(7) Thaum lub sij hawm pouring txheej txheem, khaws qhov kev ncua deb ntawm lub ladle spout thiab lub sprue kom ze li sai tau, tsis pub tshaj 50 hli, kom tsis txhob oxidation ntau dhau ntawm cov hlau molten.
(8) Rau ib lub sprue nrog lub ntsaws, lub ntsaws yuav tsum tsis txhob raug tshem tawm ntxov dhau. Tom qab lub sprue tau ntim nrog cov hlau molten, maj mam tshem lub ntsaws ntawm lub kaum sab xis kom tiv thaiv kev tsim vortex hauv cov pwm raws.
(9) Molten hlau tsawg dua 60 mm saum toj ntawm lub crucible yuav tsum tsis txhob siv rau casting.
