CA2060768A1 - Roll, comprising cemented carbide and cast iron, and method for manufacture of the same - Google Patents

Abstract

Summary The present invention relates to a roll, comprising cemented carbide and cast iron, and method for manu-facture of the same. The roll may be used for hot or cold rolling. The barrel comprises one or several cemented carbide rings, cast by centrifugal casting method into a roll body of an iron alloy. The casting alloy comprises an essentially graphitic cast iron, which after the casting contains residual austenite.
This residual austenite is transformed at subsequent heat treatment step (or steps) totally or partly to mainly bainite under volume increase, with the aim of reducing or totally aliminating the differential shrinkage between the cast iron and the cemented carbide as a result from cooling after the casting.

The central part of the roll body may alternatively consist of another alloy.

Description

~.. tl~ a;l 15:5`~ tl 'ti '~ tl !;~ iU~Llt~ j;,UU`.:;UI;~
2G~r~6~

RO~, CollPRISING C~NTED CARBIt)E A~D QST IR~II, ~OD FO~ M~UFAC~E OF' ~ SAllE.

The pr~ent iT~ntion relates to c~ting ~y the 5 centrifug~l c~6~ing Dlethod one or ~ev~r al ce~ente~
car~ido rin~ i~to c~ alloy~ ~sod on iron, ~r~r~r-ably c~st i~ron. ~e reaul~ing prQduct i8 a coropc~itR
roll, ~de in one pi~e anly, ~ etallu~yical bond l~t~e~ ~ented carbidQ and C~st ~ron.
1~
Compo~i'ce roll6 wi~ cemsntsd carbide ~or hot or colà
roll~ng compr~se one or se~eral cemented ~arbide ring~ a~ach~d 'co ~ ~dri~ing~ ndle ~ ~a~iou6 COUplin9'S and loc3c~ng devis:es. One me~od o~ trans-15 ~itt~ng t~ orqu~ fro~ ng ~pindle to ~ec~nted carbid~ r~ to u~e ~ceyYays or o~2er d~iving groo~es or ~iYing lug~, ~ac~e integral with thQ cented carbide ring. ~lo~ver, ce~ent~d c~rbid~
i- a brittle ~ater~al wlt~l lt~ite~ tensil- ~treng1:h 20 an~ ~pecial notch 6~nsitiYi~y such as in $nner cor-ne~s in above mQntioned de~ric-s for t~e torque tran~-m~ssion. Methods based on such con~entlonal joint~
ha~re wor3c~d uns~i6~ac~coxily. Anoth~r me~hod or t~e torque tran~ission is by mu~n~ o~ ~rictional ~orce~
25 at t hs bo~ec 8~face oi thQ cemented carbide ring .
HaW~YQr, the radial ~O~CQ on ~li5 8urf Ae- giVQ~ ris~
to tang-n~ial tensilo ~ressec in t21~ ~ented carbide rislg ~ith a maxs~um at lts inn~r ~ia~tor.
Tl~es~ ten~ile ~t~en~e~ addcd ~o ot~er tensile 30 strQs~s, qensrate~ when t~e roll i9 ln use.

ca~tlng o. c~ing of ~n iron ~iloy onto ~ c~mented c~rbide ring a co~posito roll ~O:F hot or c~ld rolllng is obtain~d, in w~ich re~ired devlco6 ~or torque 35 ~ran~jml~6ion may b~ ated to the cast i~on, s~ ror example th~ S~edls~ pntent No. 7~00170-S, publicatlon ~2 U~. O~ 15~ 108~ S.~'D~'lK .IUR ~ LI~`C~ bDOD3, 015 2~0768 a nu~P~r 371114. ~o~Qr, t2~ia i~ not An ~n~ir~l~
s~mpl~ proble~ UQ to t~ f~ct tllat du~ing cooling t~se e~s~g ~hrin3Cs 3110r~ ~an ~he cemen~Qd c~Lrbid~
ring, in~-ard~y d~r~ctQd forces on 1:hQ c~men~ed 5 ca~bid~ r~ng are pro~uce~, gi~ring rise to axially dir~c~Qd t~ le st~c~ns os~ 'ch~ outer sur~ace o~ t~e ce~nented carbide ring, whic~ are ac~ing perpend$-etllarly ~co ~nlcro cra¢~c~ g~n~rated in the roll surfa~
during rolling. Under thn ~nfJ~ue~GQ o~ eso ~ensile 10 s~resses th~ ~icro cr~cks p~opagat- ~n depl:~ w~$c~
~nay oau3- roll br~;age or need fo~ axc-~ssi~ s-ing ~oun~c, li~iting the ~otal roll~ng cap~ci~y of t:he roll.

15 A ~lution to thl~ pro~le~ is de~;cri~ed in ~e S~edi~h p~tetn'c ~pplication No. 8804S03~4L, according to whic~ one or se~l c;em ntsd carb~de ~in~i are cast intQ ~ casing of an iron alloy, at ~rhich t~e c~t ~ y co~prises an es~ntially graphi'clc cas~
~o iron, ~hlc~ A~t-r the ca~ting containS the structure alc~0ent resid~al ~us~nit~, pre~rably 15-20 perc~r~t by w~ight, ~l~ich ~t subsegu~nt on- or s-~raxal heat ~ atmen~ ~'cep~ ~ota~ly or par'cly i8 trans~or~ed w~der volu~e ~nc~eA~L to ~oainly bain~t~ e 2S of reduc~ng or totally eliminating th~ d~f~er-ntial 6h~intcage l:~t~ ~e cast ~on ~nd tb~ c~er~ed carbide as a r~sult rroln coolinq aft-~r the casting.

~l~e me~od acoord~ng to ~u ~ent~oned pntent a~plica- 0 tion per~t~ roa~ act~lre o~ n~2ely roll rings, ~i~h n by co~plir~g~ ~nd loclcir~ de~riee6 on A dri~ ing ~pindlQ ar- ~s~ea~lsd eO a co~plet~ roll. ~ven i~
n~Q~ry oouplings for the to~que tran~ ion are ~ade in the ~a~'c iron part ~er- ar~ d~en~ion~l 3~ ations zmd th~reby a limit for t~e tra.n~ittabl~
torque. Furt~l~r, ~ wear resi~tant ~r~acQ tth~

`9~ 02.~ 15:53 ~S~B .B ~lOS~ S~!;D~ R ~ LI~G QloOl 015 _ 3 2~76 b~rel) of ~e rolls is dimens~onally re~tricted.
A~cord~ng to the ~entioned ~et21o~ or ot~ xis~ing ~ys~e~s of ee~nen~d ~arbid~ roll2~, operating l~y ~y Q~ ~o~- kind of torque ~rans2~tting couplin~, 0:2Q lS
5 not totally rree to place ~:emented carbide rings on t~n barrQl ~ec~u~e of ~pace re~uiring coupl~ ; and lod~ing devicQB. Thereby, tl~ face to ~e used ~o~
- rolling ~co~ ubstantially re~tricte~.

~0 C~ntrifuga' easting ~1~ a ~ell kno~n ~e~uc ~r ~anur~e~ure of uaually rotary ~ymmetsic ~à~s~
t~l~UliqllR ut.~liz~ c~ntrifugal ~o~ee, ace~mp^
li5h~ a rot~ting cy~indrical 3~ould, to ~ling t~
sDol~en m~al again~t ~ a:t.18 0~ thf~ n~ould, ~ere i~
15 solidi~ie~ und ~ pra~E;ure to ~lesired ~pe. ~8 ~cbni~ue 1~ coDm~onl~ us-d ~or ~anufac'cure o~ tub~s, llnings, b~hQs etc., but i~ a3.~o u~e~ ~or manuf~c-turc or ~oll~. Fo~ example, by ~e S~edlsh patent applica~ion ) o. 8603987-2 a co~opo~:ite roll f or hot or 20 cold r~lling ~ 8 kno~n, ll~vi~g ~ centxi;uslal cast ou~er wear re~ nt layer or casing o~ a high alloyed cast steel and a cor- o~ ~ ~crm~cular cas~
iron, ductll- ir~m o~ 8i~ ca~ ~t~

25 According to th- ~nvention ~ c~posit~ r~ now provldQd ~ade in one piec- only by ~ear,s of centri-~ugal cast~ng with ~Datallur~cal bon~ ~et~2n ~ n-te~ ca.rbi~l~ and cast iron, vtler~ th~ barrel ~ay be egu~pped -~lth onc~ or s~-eral cementsd carbide ring~
30 llcco~d~nSI to ~c~ual ~rolling ~onditions and reyuire-m~ts. T~is ~reed~m in design i~ possi~le to nchi~ve ~nly by ~he present i~ontion.

~i~ure 1, 2 and 3 sho~ ~o~oe alt~rnative ombodiment~.

.

`9~ oq~n;l 15:~3 ~ lOS~ S~D~rlK ~TUR ~ `O~L~'G ~hllO5~015 4 ~ d 5 ~3 ~6 8 Figur~ a rc~ o~ ~uctile iron ~ in ~rhiGl a c~m n~ffd c2~rbl~e rin~ ~2) i~ ca~t in.

Fislur- 2 6110~:; a roll of ductil~ iron (1) in ~I~ith 5 four c~tmented carbide ri~gs ( 2 ) a~e ~:ast in.

Figure 3 ~ovs a roll ~ri~ four ce~t:ed car~e rinsl~ (2~ as~ in ~uctil~ irc~n ~1~ and ~ith eor~
jcurnals in anothcr ~teri~l t3).
moulding o~ ~he ~:~on~ed carbid~ ring or rings in t2~e o~ ry ~and ~u~t ba made in such a way that ~he ~oltnn c~st lron ~s proYen~ed rom r~ac~in~ ehe outer ~12r~c~ O~ c~mented ear~ide ring. ~i9 is pro~en 1~ eO ~e po~sibl~ ~y tt~ in~ntion.

T~ outer 6ur~ace of tne c~m n~ed car~ide ring tO~
rinç~) fors4~ tho b~rr~l o~ ~he ~anufac~u~nd comp~l~lte roll. xpQrience Srom previou~ manufact~re of Ca~t-in 20 ~oll rinq~, accordlng to the pat~nt a~plic~tion No.
~04503-4, ~how~ at a sm~ll amoun~ of mol~en c~st iron, havin~ pen~-ratea th~ outflr surf~c~ ~f '~h-c~nted s:arbide ring, re~ult~ in det~riorated sur-fac- guality of ths c~ t~d ca~bidc undor the pene-25 tration s~rface. ~ mac~ ing one or a ~v 2n~meters c)~ the outer ~ur~aCQ of t~ nted car~id~
ring e}~i~ surface det~io~a~ion can be r~ovQd. ~c~r ~uccessrul ~anufacture of a composit~ roll according ~o th~ prese~ in~ention such ~urfac~ penetrat~ons 30 ~u~t be ~void~ u~ RC~Crdisl9 to a~o~e, i~ possi-ble .

In or~s to achie~- optimum ~etallurgical bond bet-~o~n cement-sd ca~b~ d~ and c~t $ron i~c i5 neces~y ~5 to usg hi~h o~er-t~p~-ature o~ th~ iron in th~
cradle, co~ob~ned wit~ ~ount controlled ~lling Or 9" O '- U3 15 ~ 5~ lO~ ND~ `R ~ WLl~ OU~:015 ~ o ~ ~ r~ ~ ~

~e s~ould ~nd ~ d4ter~in~ spc~d o~ r~'cat~on, to get ~ ~alancod h~tin~ and ~lt~ f a 6urfaca l~yer of t~e part of the c~-nt~d carbide r~ng vhic~ is not moulded ~ n tt~e foundry ~and, i . ~ e p~rt that s~all S b m~tallurq~cally bond-:d to U~e cast iron.

The pr~seln~ co~ i~e ~oll co~ e~, a~ter nec:e~sa~y heat tr~at~en~ and machinin~ to rlnal ~h~p~ and ~i~onsion, a co~plcte roll or roll rinq. ~Q diffi-cult~ec ~lt~ axl~ein~ ee~ent~d car~ido ~oils to ccn-~idontly trans~it ~chQ torauQ fxo~ thQ d~i~ring spindlR
~o th~ cem~r~tad earbida part, ~ viousltr d--scrlb~dt l~a~ been ~l~m~natRd vi~h this co~posit~
~oll .
lS
Accordin~ tc~ the ~ n~rention th~ cemen~ed carbide is ca~ in~o an ess~ntially qraph~t~c cas~t iron v{th a composition ad~usted to the carbon ~guivalnnt, C~r., in a w~y ~e~cri~ed in the S~edish p~tez~t No. 860~28g-7, publi~ation n~e~ 399gll. ~!he co~rposi'cion of the ea~t iron i~ al50 ChO~ th ~eg~rd to optimum mQt~llurs~ical bond t~ c~nnted car~ide, tt~ its c~n~, toughness and hardn~ss, all s~cossary ~or the t:r~n~ s~ion of th~ torq~e and to ~ts 2~chin-ab~,ity. By addition of f~r~o-~ilicium-magnesium and/or niclc~aa-magn~sium t~2e ca:-t alloy gets ~1 ~agn~-5i~ ontent Ol' D,02-0,10, pre~ ly 0,04-0,~7 p~rcRnt ~y ve~ght. ~ inocula~lon ~ rro-~iliciu~
~Q case i~o~ ~ets a silic~m cont~nt o~ 1, 9-2, 8, preferably 2,1-2,S perc~nt by ~eigllt. I~re~y a auc~ ron ~s ~airled ~ g disp~rsod, sp~lexoidal g~p~ h~s duotile ~ron ~as a har~nRss-to~ynn~ss-st~engt~ which is w~ll balanced to the application.
`'n ~eat tr~a'ced condition the Brin~ ardn~ss ls 3S 250--300. Furt~er, the iror. ~hall be all~yed with ~u~tenite generating alloying ele~nent~, pre~rably ` 9~ 1 15: ~3 ~ S,~,~'D~ I'R ~ LI~ D07, 01S
~ ~ ~ 5 s 6 ~

n~c3col in a~no~n~ of 3-10, pr~Rrabl~ 4-8 percent b~
~ightr r~ulting in ~ c~r~ain amoun~ o~ re~idu~l austenite viz. 5-3~, p~e~ bly 10-25 or rat~r 15-20 percant by YQight ~t~ t~a caeting. By 22e~t t:reat-ment ln on~ ox s~rcr;~l steps a ~ui~ ~ount of residual a~;sten~t~ c~n und~r ~olw~e incr-a~
tran~;~orn~ed to ot~er Stn~cture el~m-nts f~r ~xamp~
~aini~e~ ~hi9 ~olumQ in~reas~ can be so adjuste~ ~at ~ehQ differen~ial ~eil*a~, taking plac~ in the ~0 co~po~ite roll during coolin~ from the cas~ing ta~-pera~ure, can be tot~lly ~r p~rtly eliminate~. ~he mQthod for tb~ he~t tr~atmen~ ~ adj~te~ to ce~en-~ed car~do gra~n, sompositi~n of the cas~ i~on lnd t~ roll ~pplication. The h~t ~re~ nt includes ti~q t~ and ~o~ding a~ a ~emper~tur~ o~ ~00-lO00 : C, coo~inq to a~d holding ~ a t~mperature o~ 400-~o C, and cooling to ~oo~ t~perature ~n an alt~na~ive e~bodiment the roll comprises a : 20 cQm-ntsd carbide ring tor rings) and a casing of ment~oned c~t l~n only, wh~reae roll co~e nnd ~our~als aro ca8t of anothQr casting alloy either by c~ntri~ugal or ctatic ca~ting.

In another ~lt~rnati~c ~bodi~nt the roll compri~es cement-d carbid~ ring ~or rings) ca~t ih~O a ring-shaped ca~in~ ~nly.

Accord~ng to the inYention th~r~ i~ also ~rov~ded a r~ethod for ~nanufac~ur~ o~ a co~plete c6me~2~ed carbidQ
quipped roll ~or ho~ or cold ~ollinq. ~ccor~ing ~o tha ~thod ~t lea~t one sint~red cem~nted carbid~
r~n~ ~ placed in ~ ~ould in a cent~fugal ca~tlng equip~en~ ~ith the ~ore sux~acn of the ring and its si~e ~ur~acos fr~ to e~ablish contact b~t~e~n c~Dc~ted c~rb1dn and c~st iron. T~e ~ould la rotated u ` ~ n~ S.~?lD~ R ~- I;O~YLI~'G lDoO6-01~
rl~ 6 8 ?
and ~ n prop~s spQeq i:~ aenie~ed a ~olten cast iron with ~ov~ d~scrib~d c:o~positioTs a~d ~ita~lQ t~
3:a~ure is tapped do~n into ~he ~ta~:ing mould, in doing ~rh~ ol~n ~o~ i~ slun~ aqainst ~ lrall of the ~ould and ~olidi~ie~ er pressure. After cooling ~o room temp~ure the roll is cleaned and is ~en heat treat~d according to a~ fe.

~c~ord~ng eo an alternati~e metl~od a c~ ed ~r ido lo ring ~or ring~) is ~ast into a c~sing or ~2nt~0ned ca6t ir~n onl~, a~ter which coro and ic~urnal~ arQ
cast c~ ~noth~r cast ~lloy ~ither by cen~rifugal or ~tatic c~tin~.

lS Acco~dinq to anoth~r altern~t ~ v emb~d~ment a ¢e~nteld carbide ring (o~ r~ ngs) i5 ca-t into a r~ng-shaped cacirlq onl~, by ~;entri~ a~ ca~tinq.

Exa~nD~ Ç
A sint~rod ~ entea oar~ide ring ~ith 'ch~ composition 70 % tunq3tcn carbide ~WC~ ge cobal~ (~o), 1 nlcXel tNi), 2 9~ C~rO~UIA (~) ~ all p~rcent ~y ~eight, ~a6 molded ~n ~oundry ~n~ i22 a mould in a 25 v~rtical centrifugal casting machins. Tt~e dlm-nsions o~ th~ ce~ented car~ide ring w~
- C~uter diameter - ~n~er di~m~ter - Widt~ lO0 m~
r ~h~ moldin~ ~he ~re sur~ac~ of the ce~nentQd carbi~e r~ng and i~s ~id~ su~f ac~ t~-n t~e inn~r diAD~e~er ~nd a ~1ametc~ of 310 nm ~e~B fre~ in ordcr to tbere create a me~allurgical ~ond ~et~fee~ the 3~S csmented carblde and th~2 cas~ iron.
~e ~ould ~as ~ut to rotate at 400 revolutions per 02.~03 15:S6 ~ `'B ''81U8~ S.~ JUR ~ (X)~L~.~`G ~O0~rUl5 ~ ~ ~ O ~ ~ g ~inuto. 3~A c~-t iron ~ U2c ~ po~itiOn 3,7 ~6 c~r~on (C), 2,~ ~ ~ilicon ~Si)~ 0,3 % ~angan~se (~n), S,4 % nlcXcl ~Ni~, 0,2 ~ molybd~u~ t~o), o,OS S
~agn~si-~ ~Mq) ana ttle 2~lance i~on ~re), all p~rcent S by ~eight, ~t a te~porature o~ 1~40 oc was tappad into t~e rot~tiny mo&ld. ~le duration of pou~in~ ~as a~out 1 ~nute. During that ti~e t~c r~e~tion gra-dually ~:~a~d.

10 Aft-r ~ cooling th~ CO3~1pOSit~ roll ~a~ clea~ed nd checked ~ an ult~a~onic ~od.. ~he quality o~ t2~e m~tallur~ical bond ~ras good.

~ho roll ~as ~eat tr-ats~, wi~h tl~e ai~ of tsans-15 ~onning t~ ~esid~a~, au~enl~e 'cc baini~e, ~ hoat~
to 900 ac, holdins~ tim 6 hour~, t~en cooling 'eo 45 'C, holdin~ t~ne 4 ~our~, fol~owed ~y ~ooling tc ro~
t~mporature. ~h~ Preely ~06ed sur~aces of th~
cem~n~od c~rbide ~ing ~re cover~d v~ an anti-20 ox~dizing ~nt, as tho hsat treatmQn~ was p~rfo~din operl air. She roll d~ lons ~rere:

~arrel: ~310 ~ (ce~nt~ cdr~ 340 ~) * SOo ~.
Journals: ~220 x 300 ~ + 22Q x ~2

Claims (8)

1. Roll, preferably for hot or clod rolling, by which the barrel comprises of one or several cemented carbide rings cast into a casting alloy comprising an essentially graphitic cast iron, which after the casting contains 5-30, perferably 15-20 percent by weight residual austenite, which at sebsequent one or more several beat treatment steps totally or pertly is transformed under volume increase to mainly bainite, with the aim of re-ducing or totally aliminating the differential shrinkage between the cast iron and the cemented carbide as a result from cooling after the cas-ting, c h a r a c t e r i z e d of the roll in-cluding journals is cast in one piece, which is later machine to final shape and demension.

2. The roll of claim 2 c h a r a c t e r i z e d in that the roll is made by centrifugal casting.

3. The roll of claims 2 c h a r a c t e r i z e d in that it comprises a casting of said cast iron, holding one or several carbide rings, and a core and journals cast of another cast alloy by cen-trifugal or static casting.

4. The roll of claims 2 c h a r a c t e r i z e d in that the roll comprises a cemented carbide ring (or rings) cast into a ring-shaped casing only.

5. Method of manufacturing a roll, preferably for hot or cold rolling, in which the barrel com-prises one or several cemented carbide rings cast into a casting alloy, comprising an essentially graphitic cast iron, which after the casting contains 5-30, perferably 15-20 percent by weight residual austenite which at subsequent one or several heat treatment steps totally or partly is transformed under volume increases to mainly bai-nite, with the aim of reducing or totally alimi-nating the differential shrinkage between the cast iron and the casting after the casting, c h a r a c t e -r i z e d of the roll including journals is cast in one piece, which is later machined to final shape and dimension.

6. Method of claim 5 c h a r a c t e r i z e d in that the casting is made by centrifugal casting technique.

7. Method of claim 5 c h a r a c t e r i z e d in that by centrifugal casting the cemented carbide ring (or rings) is cast into a casing of said casting alloy, after which roll either by cen-trifugal or static casting.

8. Method of claim 5 c h a r a c t e r i z e d in that a ring-shaped casing only is cast.