CA2001396A1 - Process for manufacturing cast components with integrally cast, at least approximately gas-tight high-temperature insulation - Google Patents

Abstract

Abstract Process for manufacturing cast components with integrally cast, at least approximately gas-tight high-temperature insulation A casting with an inner high-temperature thermal insulation (2) is manufactured using the full-mould casting process such that efficient, flaw-free mass production of castings with thin walls and close tolerances is feasible. As a result of the impermeability to gas of the high-temperature insulation (2), however, the steam in the expansion mould cannot be routed transversely through the wall of the model. Because of the insulation effect of the high-temperature insulation (2) it is feasible to route the steam over the periphery of the model and extract it at the opposite side without its heat content becoming too low in the region of the steam outlet to permit complete expansion there.
(Fig. 2)

Description

49-~lt,l-6~ 6 l~uh~e~ c k~r ~I. Pa~ . '313g P0~ 23. 11~ 44 'Z~ L39~

P~oce~ for ~an~fa~turin~ ce~t compon~nts ~ith l~te4r~11y cast~ at le~t app~axim~tely ga~-tight high-tornpe~ature in~ul~ti~n The pres~nt invention re~etes to e proce ~ ~o~ ma~ufact~rin~
c~st ~omponbnts w~th int~yrally e~t hlgh-teinperature insulation which is ga~tio~ht by Yirtue 0~ 9 ~le~ c ca~
or hlgh-t~mperatur~ ln~ul~tion ~hich hin~er~ ths pa~g~
ga~ in a~cordan~ with the g~neric part o~ clai~ 1.

Work haa bee~ in progrr8s fer ~ome tlme to prov~d~
p~rticular~y ~a~-bo~ing component~ of lnt~rn~l co~buotion eng~nos 6uuh ~8 tha combu~tion ohAmbor, th~ preaombustlon cha~be~ l chamber, piston trough~ sxh~ust/lnlet port~, exh3u3t m~nifold~ pipea, turboch~g~r or gas turbine hou~ing, with a hlgh-temperet~re Shorm~l in~latio~, as e~ nc~d by Ge~man patant appllcation~ 3~ ~3 591, 34 11 ~35, 34 46 649 ~r 35 21 467~ Such a th~rmal in8ulation p~r~it8 the eff~ie~cy ~r power ~enalty of int~rnal oo~b~stion ~ngine~ to ~
ln~rea~ed ~nd their Hnvlr~nment~l pollution to be r~tUced.
For ex~mple, the u~e o~ hi~her tsmpera~ure3 ln th~ exhau0t 8yc~em of ~n intern~l cambu~tian Qngine enco~r~es a reducti~n ln the disoh~gc of carb~n ~onoxldo beoBUa~
mo~e ea~ily oorlv~rtod to ~r~on d~xld~ ~xhau~t ~a~
~crub~ing con ~l180 advantaqRuu~ly be carrlcd out ~t high6r temper~turo~.

In thi6 ro~ard it woul~ thsoretL~ally b~ ~oirabl~ to ~tt~pt to ~xacut~ all gas-besrlng w~lla in ~ ~uitably hYat-r~el~t~nt thormal i~sulat~on m~t~rlsl in prsotiee, h~wevo~, th$s i~, of aour~ nut posalble in vi~w oF tho prea6ure~ obt~lning und ~th~r mechanicel ~ltr~89e~3 ~ with tha result that the g~-b~r~ng aomponent in pr~ctico requ~o~ the support of a loAd-b~r~ng ~etallic Component, mo~tly e castlng whlch, ~or ~g-~ælt,l-~ J~396 3æ'3 F~-~3 ~ 9 0~:45 ~ea~on~ of the~n~al technoLog~ ~ iQ ~v~nt~geou~ly mo~ntl~d on th~ ~u~sid~ ~f th~ wall o~ th~ ga~-b~rin~ c~nnp~n~nt.

A hish-tsmpe~a~re ir)~ulation sy~ten~ parttcul~rl~ for roeiproo~ting-pl~ton interrlal co-~b~tion englnea known ~s ISOLITE is knawn in tho art fro~ pu~llsh~ produ~t litbr~tur~
of G ~1~ Mont~go GmbH .~n whiCh an in~ul~tlng bady is pr0fnbrioated ~f ce~mic ~lbro~ con~sting of Al203/5~2 ~la~
on bath ~ido~ ~ith C thin otsinlo~ st~1 she~t and then onclo3ad in h met~l ca iting. Th~ inn~r sto~l oho~t oladdls~q function~ metalllc ~u~de ch~nnel ~or ths hot ~a~os~
whil~ ths o~er ste~l she3t ola~in~ pr9vent~ mnlt3n mq~3 penetrating the lnaul~tlng ~at2r~1 dl~rlng tho o~ting procv~. In thi~ ~oy an into~ral oolllpo~l~nt i3 creatod with load-boaring C~19t wall Pg tho extern~l layor flnd o high-t~persturc thermcl ins~latinn ~Hyer c4nrlect~d direotly to thi~ with a amooth ste~l delinoation ~f the i''lo~ ~p~ce.

Tho ea~ting Of ~uch A componentS how~ver~ i~ not ~ithout d~fficult~- A~ a rule~ th9 end flan5cs of t~be-~h~pod componsnt8, e.g. an ~xhau9t m~nifold~ are m~chine~flni~hod which ~o~ns th~t the hlgh-tempcratur~ inaul8tlon m~st termlnete b~r~ tho axial ~r~d of the oompsnent. ~hus ~ring ca~tin; the high-temp~atur~ lnsulatlon mù~t ~e hold ~n oc~es ~hi~h ~o a~lh~2~tad to molt~n m~ in the ~xlel viclnlt~ ~f the high-tempor~tur~ in~ul~tion. Thig ~e~u~t~ in problem~ in c~nneo~icn with ol~an ~ntrin~ ~o th~t the wflll ~hickno~ ~f tho c~tlng Q~nnot be l~a8 th~n a quit~ sub~tan~iaS v81ue~
In addltion~ the hard cores most be removed ~rom the inno~
space o~ tho ~4a-conv~ying channel ~fter tho castlng pr~c~
which 18 costly and csn Hl~O r~sult in damage t~ the s~Qth surf~ce of ~h~ inn~r ~tool 3heet claddln~ by th~ ~o~e ~fl~, Fu:rtherm~rr~ i~ is ~i~ficult to ~void mcltnn mo~a flo~ng alDng the ~ 'qce of the r~t~ining core~ t~ tha lnside of ths steel sheet oladding.

~3~ t~ "~ .3c~ l.F~ 3 ~ ~ g~9F~ 2'~ æ:4r, ~y c~ntraet, it is the o~ject of the lnve~inn to create proc~ to manufacturo ~u~h c~ti~9s proYlded with high-~empcrat~ in~ulatio~ as are ~it~bl~ fo~ e~flcient, ~law-frea ~nd d~f~ct fre3 m~ss produ~tlon w~th a p~fe~tly u~F~
~nd ~ all thick~e~q ~f thb ea~ting.

Thi~ obJ~c~ i6 ac~ ved by m~an~ of tl e ~hara~ter~stic foatures o~ claim 1.

Ths u~e of tha full-mou~d castlng process for thto app~lcati~n makes it po~sible to elim~n~te t~e dis~dYant~es descrlbed above. ~he exp~ndod plaYtic shapeo c~n ~e ma~s p~o~oed ~ff10iently in appropriate ~xp~ns~on moul~3 - ln similar ~eohion to injectlon-moulded g~od~. In shapo th~y correspsn~ complotel~ to tho l~ter cn~ting ond alre~dy contain the high-t~mporature ln vlstion~ Then the co~ponent~
pr~febrlcat2t L~ this w8y wlth the U~e of expand0d pIa~tic~
simp~y need to be pl~ed in ~n approprl~tely f~uidi~ed mould medium ~uch a~ cand or the llke and, a~t-r ccn~olidstlon o~
~h~ sand, f3r cx~mpl~ ~y n~ns of vaculum pr~Yore, c~t during ~hieh the molt~n m~ ga~ifie~ th~ expanded pl~tic ~nd takes it3 placc . Sinc~, in ~he full-mould c~ting proceos, the molten ma~3 ~utomati~ally occup~e~ the ex~et spaco occup~ed proYla~ly by tho exponded plaati~ th~
dTfficulti~ Ysoci~t~d with ~izing, pooitional at~billty~
coal~ etc. ca~ bo t~nof~ d to th~ st~9~ ~t whîch the expand~d pla~tic model i~ m~nu~ctured wher~, by ~ontrast with th~ pro~e~ u~lr g molten ma8s~ ~u~h problems ar~ 909ily d~lt w~th~

E~p6ndcd pl~tic ~odel~ for full-mould castlng ~re ~u~lly manufactured by 1ntroducing expandablc plawtlc yr~nules ~nto a mould c~vity whoee width corre~pon~ to tho wall thi~kn~ss of the ca~tlng and are ~xpand~ the~e by intro~uclng a hoe~
tr~n6f ~r medium ~uch a~ ~uperheated ~t~snl~ The inlet ~o~ th~

.

~i4-n~lt~1-6~r36 l~uhnen,l~J~ck~r u.P.~ ~ag P05 23.10.~ 8:47 s~p~rhea~d st~am or tho lik~ i5 l~ated on ono of the l~ge ~urfac~ of th~ w~ll, and the steam 1~ extrs~ted ~n th~
opposit~ ~all aft~r pasoin~ through the g~onules. rhe sho~tno~s of the ~te~m t~vel thr~u~h the ~ranu ~ e3 gueranteoa th~t thc st~m ztill retains enough th~mal Bner9~ evan at it8 outlet pol~t, i~e. 1~ still aufficio~tly "unused" t~
guarantee c~plete expsn~ion ther~ . At~nt.i~n may be d~own wi~h ~egard to these conditi~ns to Ge~an patent appllcati~n~ 5~ 47 6~5 and 33 47 616, to th~ ~ull cont~nt3 of wh~ch rsf~ren~o is made.

HoweYe~, ~uch a procedu~o ~or manufactu~ing exp~nded pls~tic mod~l3 i~ not pasalbl0 fo* tho ~a~tings which ~re to b~ m~de in th~s case s~nc~ steam o~nnot pa80 through the hlg~.
t~m~oraturo lho~latio~. ~t best, thereforet the ~t~am ~an bo dr~wn Pl~n~ the high-temperature lnaulatio~ ontc the OPpC5~te side of ~h~ ~odel and th~n ~xtract~d there, Sinc~ the met~llic ws~l~ of the exp~nsinn mould ~r~ maintai~ed st ~
~on~ido~obl~ lower temp~r~ture th~n the ~te~n in ordo~ to avoid p~rtl~l premstur~ ~xpan-~ion of tho plastio g~anulas du~lng ~h~ fllling prqoess and slnce eno~gy contlnue~ to be extra~ted from ths ste~m to h~nt the plsstic gF~nules t~ the e~p4r\310n tomperature it .i~ not gon~r~lly feasl~le to ~oute st~am psrellel to the l~rge a~e~ e~ 8 ~oll if complet~ and ssturated ~xpanslor~ ~e to bo achloved Qt tl~e ~toam outlct which i~ located rar ~rc~ thc lnlet~ tt i5 e~ential ~
how~ver, thst suoh cxpanaicn bo ~ohioved in order to produce ~3sting with a flsw-f~ u~f3ce.

Thi~ diffloulty ~loc ccnnot bo o~orcorqe by introduclng th~
stoom ov-~ e prolonged period 80 that as a r~ult ~ t~o rresponding heating of the 0xp~nsion mould walls the h~t ~,oeo o~ tho ~ ly introduced ~team i~ oontinuously reduced untll rlnslly ste~m ~t the decirsd temp~rature i~ ailable in ~ho oxtraotion zone. Thi~ i~ beoause comPl~to oxp~n~lon J~ 6~ 9~ u. P.~r . ~3 Pl~6 ~3. 1~ 39 08: ~
5:~396 ~f th~ pla~tic gr~nule~ ln th~ ~teon~ inlo~ impede~ the ~t~m f ~ ~w s~oh ~hat o~ly a l~.mited volume Of ste~rn m9y b~
~ntrodu~ed. The heat ~bntent o~ tl'tis lnjection of stenrn ~uet then ~uffio~ for ~he compl~t~ e~p~nsion ~f the pla~tic gr~nul e~ .

Surp~isingly, hcw~vor ~ it ha~ bn~n 9hnwn ~hRt ~lthough on the on~ hand ~h~ higk~.tRmper~ture infiulation af tho ~st~n~s ~nufsctu~d ac~ding to the p~ent inYent~an p~o~ents the p~usage ~f o~eam thr~ugh the w~11 in ~h~ usu~l ~annsr ~ a r~ult of ~8 inSUffiOi!gllt 9~1S p~rn)e~bitlty~ On t~ oth~r h~nc becauso of ite therm~l ln~ulatlon ~fFect 1~
s~ stnnti~lly rcdu~ee ths heet loe~ of the 3toom during ita l~ngthy p~t~ ~long the p~riphery of th~ h~at ln~ulat~on mat~ri~l, a& a ~asult of whish it c~n a~ver ~ ~n~id~rably greatar distanco in th~ expan~ion nlo~ld be~ore it i~ us~d ~Jp and un~bl~ to c~use oan~pl~to oxpansi~n.

The meeeure pravided ~or in cl~im 2 en~urea ~h~t the haat 105s of the steam an tl~ sldo af the exp~nslQn moul~ ~-ppositv tho hlgh-t~nlpr~atu}~ in~ul~tion io aloo minimised~ altho~qh thi~ h~ 109~ red~ctlon is limite~ ~y th~ maxî~u~
ternper~ture of th~ expanaiort mould ~all whlch ie less than tho ~xp~r~sion t~mp~r~t~r~ of tho plaoti~ gr~nule~ ~nd is thUB
su~t0nti~11y below the 3teenl temperet~re~

Furth~r det~ils, ~e~ture~ end advant~o~ of ths InYontian ~re cunt~ined in the fallowlns description of one embadlm~nt wi~,h th~ ald of the acq~mpanyi~ dr~in~s in which:

Fig. 1 ~ho~s a ~oction thr~ugh ~ ca~ti~g ma~nuf~tu~ad lr ~ccordan~ ~ith th~ invont~on fig~ Z a secti~n thro~h the expon~ion ~oul~ perpendi~ular to the ~xl~ of tho c~eting.

4~ t~ !q~ . P~r. g~ Pl~17 -'3. 1~ 9 ~ 4~

~6--In ~ig. 1, for ~x~ple, a ca jtin~ manufa~tured ln accordance the ~o~c~o of tho inventi ~n in tho farm ~ n u~te g~
duct i3 111UBtrated~ In i'c, tho cast iron sl~ev~ of the ~Y~Sto 9~ d~t i~ d~i gnated 1, and ~ ln~loat~o a high-tempe~a~ure ~n~ulation whi~h b~gins a short di~tanc~ f ~om connecting ~lang~s 3 ~nd 4 o~ ~thoF ~urface~ o~ th~ castlng wh~ ~h h~v~ ~o ~ f iniohed ~u~h a~ the thro~d S ~hown and osY~r~ tho whele of th~ inner periphory of ~he c~stin~. Th~
hi~3h-tomperature insL~l~tion 2 consi~ta of an in~ulsting bady 6 ma~ of ~ufficien~ly he~t~esi~t~nt mn~1 or c~r~mi~
fibros covered on both sides by thin st~inle~e ~eo~l ohe~t~
~oils 7 #nd 8. tho purpose o~ the inno~ sta~nl~6s ~to~l ~h~t ~oy~ 7 is t~ provide ~ smo~th sur~ace ~hlch is r~lot~nt t~ ~ea~ c3uaed by the ga~ fl~w~ Th3 end~ o~ the innnr ~tainlesa ~teel ~h~ot 7 aro ben~ ov~ to form tong~e~ 9 ~hich pr~ ject intO~ the moterial ~ th~ cqstin~T thls fi~in~
of th~ tongues 9 i8 ~chl~ved ~mply in th~t th~ molten ~
of the ca3ting m~terl~l flows ~ound the tonsu~9 9 during the tln~ proces~ and s~lidifies there.

The stsinle~s ~to~l ~heet 8 t~rminat~ b~fore the tang~e~ 9 of sta~nless ~o~l ~hoot 7 and ~ov~r~ th~ insulating body 6 to p~ot~ct it from the ~olten ~a68 during c~tlng. The stalnlco~ ~t~ heet ~ is h~t visibl~ in the flni~h~d prad~Pt .

A~ lc plsin to D~ ~ the high-te~pe~tur~ insUlAtiOn 2 mu~t bs loo~tsd lnrldo q ~otin~ m~lld and ourrounded by th~ molten ln a~der to m~nuFscture su~h ~ cnating. The rlo~ paths mu-t, howev~r, b~ kept ~ree of moltcn m~s3 ~nt, if a unitormly thin w~ll thickn~ss is to be attRlned~ th~ hi~h-tempe~st~re insul~ n ~ust be p~ition~d v~ry ~ouratQly ~n the c~tîng ~ould .

T~TO~ b a~

~'3 -1~ b ~ b ~ I, F .~ I ?~,'3 F~ 3 . 8? 1;~;3, 4 3 In th~ f~ nould ~antin3 pro~ss wh~ u~e i8 provi~od for in th~ invF-n'c~on, t.ha ta31~ of ~ccur4te pos~t~oning of the high~emper~ture in~ula~lon 2 is tr~nsf~rr~d 'co th~
production p~oc~s ~or ~nu~acturlng th~ expandRd p~,astic mod~, 1 .e. the high. t~perstur~ ulation 2 is flrgtly surr~unded by ~xp~nded pl~tic ~t~rial which c8n be qa~ified and corr~pond~ exnctly to the shape o~ the ~astlng; th~
~atorial i~ then ge~itled when the ~olt~n m~ss i~ poure~ in and replac~ by the molt~rl ma~c. PArt of such ~n ~xpan~lan mo~Jld ls shown in Fig, z, As oan ~o s~en from this, the ~lcw psth o~ th9 latsr casting is surrou~ded by thq high-te~p~raturfl lnsulatlon 2 wlth ~he ln~ulating bod~ 6 and the atair~ s steel sh~ts 7 ~nd 8 on both si~o~. A wall ltl of an ~panslsn m~uld de~lgnltod in its entirety by 11 i8 loceted ~t a given distanoe ~ro~ th~
auter ~tainle~ ste~l shoot a and f~rrn~ ~n opening 12 which corraaponds ox3ctly to tha wall thloknes~ ~f the metal in th later ~ting. Expsnd~ble plastic granul~8 13 arc insertad into tho opening 12, a~ is al~eady known 1~ the art in relation ~ full-mould casting, and ~hen ex~nded ~o tha~ a model ~0 formod in whlch the ga~ifiable expa~ded pla3tic ~o~y i~ in the exaCt po~it~on o~ ~he ~et~1 in th~ later ca~ting.

Thc uxpsnsion of th~ pla~tl~ grQnu~s 13 ls aoh~vQd ~y p~sing ~ heat trnn~fer ~dium, gan~rally ~upHrheated steQm~
th~ough them. Th0 6tcam iY int~oduced lnto ~ho granulos 13 t~rou~h st~am nozzlcs 14 and ex~racted through approp~late norzle~ cn th~ inner periphery ~ the op~nlng 12 during thg prnductL~n of st~ndsrd model~, In ~h~ way, tho ~team pass~8 trangver~oly thr~uqh th~ wall of the model, tho~b~ c~Y~rin9 a minimum dlstanc~ ln ~he plo~tic ~ran~les 13. Thi~ 13 lmportnnt boe~e ~he ~tea~ l~s~s cn~r9y durlng it~ p~age thro~gh the pla~tic ~ranule~ 13, ~n~ thi~ energy loss ~uot b8 kept to ~ minimum ln crder far complete and uni~n~m ~pan~ofl ,161-~ ?~ al:let ll.F~ ?~ P~1~ 2~.10.~g ~8:4'~
X~ 9~

of th~ plastl~ gr~nule~ 13 ~ occur. If? howeY~r~ th~ st~
ha~ t~ ~over ~ longs~ diatsnce in the pla~tic g~nu~s ~ 'che 3n~rgy loss qu~ckly beco~e~ ao high that c~mplet~ exp~nsion in the ~eam outl~ zcne c~n no longer b~ ~uar~nteed. It s~ould be noted tha~ th~ steam inlet ls increasiffgly impedod esUlt, o~ th~ ~xpan~ion pI~oc~6~ o~curri~g thers beC~u~e th~ inter~p~es b~otween ~he granale~ ar3 redue~d ~urino ~xponsio~ clr~d fln~lly di~appe~ complot~ly~ with the rl~8ult that o high raeiYtance to the eteem fl~w quickly buildg up.

lt i~ ~elf-e~ldant that tran3~r~e ~low of th~ pla tlc granulo~ 13 ln the opertlng 12 is not pos~ble if th~ in~er sllrfac~ of tho ~pening 12 is ~ovor~d ~uch thst it le e~entl~lly ~o~tight, ~Uch a~ i8 th~ ca6e h~re be~u~e Of ths ~tslnles~ steel ~h~et 8. In p~ace of th~ ~tainle5s ste~l ~hee~ 8 i~ wo~ld alQo be pos~ible to u~o a ccrami~-based bl8cking sueh as zircon oxi~o althou9h il; w~uld be es~ent~el for this to b~ diffusion-proo~ to prevent ~tearn p~notrating ~h~ i~sulating body 6. ~`or ~uch ~ design tha u~e of the full ~moulding castinQ pro. es~ canno~ no~mally bs c~n~i~ered .

It h~ boon ~hown, howev~r, that ~h~ therm~l ln6ul~lti~n effoct of the high-tempe~ture in~ula~ion 2 ~æ ~u~fioient t~
koep ene~gy 10s9 by the ~to~ low ~nough on th~ ~lde of ~he oteel ~hlo~t e ~ ~llow the steam to ~o~io~ ~ con~iderab1y ~reater dlstonc~ through the pla~tic gr~nulea b~oro it i~;
used up and un~lo t~ continuo to cau~e compl~t~ ~xpar~ n.
~ecauoo of th~ ~nsul~ting b~dy ~ which gre~tly l~mita he~
flow th~ough the stainl8~s st~ol ~haot 8 it 15 surpr~,31~g to note th~t it i9 poseibl~ to ~out~ tha ~team to both eides over the perlphery uf th3 hl~h-templlrature in4ulstlon 2 and t~ ~llow it to ~xit thro- gh ~ppr~pr~at~ outlot nazzl~s 15 tho ~ide oppoeite th~ ~t~m no~to~ 14. thi~ proce~6 use~ull~
being enhanced in a woy w~ h i9 ~lroa~y known ~n th~ art by m~an~ of vacuum prea~ur~ at th~ outlet nuz~l~s lS. In th~

13~1b~ Il F'.~-, gE,q Pll~ '3. 11~1. 3~ Y~

8x~mple d~ori~d~ the ~up~rhe~ed stoam i~ ~upplied to the pla~ti~ ~ranul~s 1~ through the stes~ noz71~o 14 at a temp~ture ~f 120C, and exlts ~t ~h~ eutlat n~z21es !5 at a temp~ra~urs of 11~4C ~lch i~ still 5uffici~ntly above th~
expan~i~n ~empesatur~ o~ 105~C cf the plastlc g~anules ~ in the oxample.

R-adings h~Y~ ~hown th~t the m~tallic ~lls ~ o~ the s~pan~lon mould 11 aro rcspon~ible fo~ a ma~or p~rt of tho h~tt less ~y the ste~m. I~ th~ open~g 12 wsre deli~itod ~n both gid~o ~y ~alls 10 of the ~xpansian mould 11~ whos~
t~mpoIat~re ~lf-evid~ntly mu~t ~lwcys be clea~ly b~low that of tha ~xp~nsiOn tempe~aturo~ exce~Y~ h~at loas would ~e unav~id~bls. I~, howe~er, th~ high-temperature i~3~1stion 2 1~ loc~ted ~n the inslde o~ ~he expanBi~n mauld 11 ~nly the extre~sly 3~all mass of tho thin s~a~nle~-e steel sh~t 8 is heated up to the temporatu~ of the st~a~ ~h~le the tempe~ure in the insulating body 6 quickly falls, w1th the r~sult that only rninirnun~ heat la8s Oe~CtU~6 to the in~lde af the ex~nsion nlould 11.

I~e~t 103~ a~ tho outelde of ~he opening 12 lrlto the w~lls lC
of the sxp~nston n)ould ll can, how~ve~, be llmit~d by rai81ng tho tHmpernture of th0 walls 10 auch th9t at, ~o~ exampls, 90~' it i~ æt:ill cl~arly below the expanalon t~mp~rRtur~? of th~ plastlc g~an~ 13 ~ WhL~h m~ans that promat~l~e ~xpan5ion ~o~ not ~ccu;r durln~ th~ filllnq proce~s. To thi~ end~
el eotricsl he~in9 e~s~ent~ 16 ar~ insert~d in khe walls 1 af the e~pansian mould ll in th~ embodiment sho~n.

After the expsn~ion pr~c~, the expandsd pla~tic ~nod~l wlth integral hish-temp~ratu~e insulation 2 look~ 80 illustr~t~d in Fig. 1~ ~lthough in~atead of tha ~le~ve ~ sh~wn thero, wal~ of ga~ifi~ble plastic m~t~rial sre pro~ont. An ~pprOpr~ate blaek~ng c~n now b~ appli~d to the ~urf~co~ of Ig~ 16i-6_13'33 k:uhrlPrl.~ Pr 11 Fc~r . 3~ Pll ~ C 88 0~:51 ~.
the exp~nd~d pla~t~c ft~teL~i~l, aft0r whlch tha oxpanded p~a~tie mode~, whioh un~ik~ the ~'inished s~tlcle i8 provld~d r~lth a g~t~ 6ys~em, la embedded in a ~ id~s~d bed of mould matrrial ~uch as ca~l~in~ sand and th~la ~ncl~sod in ca~tlr~
~And. If the o~g~ nd i~ ~n~olldat~d by a v~çuunl ~nd/ar vlbrato~y pro~Ba it olDsaly aur~ound~ ths sur~3ca~ ~ th~
~xpanded ple0~ic ~aat madel ~and th~ free ~ur t o~es D~ the h~gh-t~mpor6ture insulat1 on 2 . Molt~n metol can than be poured into the ~asifi~bl~ ~xpanded plast~c via t.h~ ~ate sy~t~m~ h8raupon the pl~ i3 g~s~flod l~nd repl~ced by the ~nolt~n m~ which ft ll~ ev~ry ~re3 ~p~o betw~9n the heat~
reSi3tont bl~c~<ing of th~ expanded pla~t~ ~edel a~ tl~o surfac5~ af ~he high-temPe~otura in~ul~tion 2 car~tigU~u~ with the oxpc~ded plastic mod~l 90 that the de~lred c~ctln~ le f orm~d .

Claims (2)

1. Process for manufacturing cast components with integrally cast high-temperature insulation (2) which is gas-tight for example by virtue of a metallic cover of high-temperature insulation (2) which hinders the passage of gas with a periphery on the side of the casting material which is impermeable to molten metal, in which the high-temperature insulation (2) is introduced into the casting mould and the molten mass is added and brought into contact with the high-temperature insulation (2), characterised therein that the high-temperature insulation (2) is initially inserted into an expansion mould (11) in a location which corresponds to its later location (12) in the casting mould relative to the mould cavity for the molten mass, that expandable plastic granules (13) are introduced into the expansion mould (11) and expanded by means of a heat transfer medium such as steam, where the heat transfer medium is routed through the walls (10) of the expansion mould (11) on the opposite side to the high-temperature insulation (2) and extracted on the opposite side of the workpiece, and that the expandable plastic model thus formed with attached high-temperature insulation (2) is place in a casting mould and cast using the full-mould casting process.

2. Process according to claim 1, characterised therein that the walls (10) of the expansion mould (11) are pre-heated to a temperature below the expansion temperature of the plastic granules (13).