GB2263875A

GB2263875A - A process for heating thin metallic sheet and a furnace for carrying out the process

Info

Publication number: GB2263875A
Application number: GB9301525A
Authority: GB
Inventors: Heinrich Patalon
Original assignee: Didier Ofu Engineering GmbH
Current assignee: Didier Ofu Engineering GmbH
Priority date: 1992-02-06
Filing date: 1993-01-26
Publication date: 1993-08-11
Anticipated expiration: 2013-01-26
Also published as: GB9301525D0; FR2687769A1; DE4203395C2; DE4203395A1; GB2263875B; JPH0610034A

Description

2263875 A PROCESS FOR HEATING THIN SHEETS OF METALLIC MATERIAL, AND A

FURNACE FOR CARRYING OUT SAID PROCESS lhe invention relates to a process for heating ilietallic h1 e a t e d rn a t C _ i in -DarLiCUle-r thin slabs, Metal sheets and steel bands, in Iii,--',-ten--perature rolling turnaces 0 v,i th 'LOTD and bottom heating, and cc),r.prisinC- especially cooled furnace rollers arranged in the transverse direction of the furnace for transporting the heated material, and a furnace for carrying out the process.

0 Thin slabs, metal sheets and leader tapes, which are rolled to a finish in broadband or thick sheet runs, have to be preheated to a rolling 'L--r. -,p,-rature of bet-ween a-,,-)1Dro--,zii-.iately 1 J50 and 1,2500 C prior to entrJ, 4.1 i lit 0 the f irst roller f. rame. The aforementioned preheating is of ten a-chieved by means of fuel-heated 1 rolling f urn a c le s walking-beam lurnaces or electric induction furnaces.

From the E11 0 313 720 A2 is known a furnace wherein the 'ed material is discontinuouslv transDorted. via a h e a L rolling furnace systen, or a rollingVxalking b - r)ea,..q s-, resiDecti,,elv. the furnace the conveyer rollers of which are arranged -,Xternally on the lateral furnace walls to be movable, to and fro transversely to the conveying direction of 'the heated miterial and to be moved through matching wall passages c 0 - into th e furnace c"---mber and underneath the heated a! s for only a short period of hea, ted-material transport lif tting the conveyer rollers. or %,,,h;,-n the SettlinC fr-ames. the conveyer rollers talce 2 U3 _. % ted ritaterial a n d t r a -- S -,10 r t i t S f- e -, w S e ic,r-,7aid by terr-porally short rotary movenents.

I n the even t 0 f 1-1, u -- 1 he a -- ed r o 111 -- 1 furnaces -- r p 0 w--'Lk-n,--bea-.a surfaces, tile f urnace 1 e n h a specified furnace output is particularly by Lhe maxinum admissible furnace t empera 'L Lire and by the number of axes of transport rollers, or transport beams respectively, and the distance thereii-,b--'Lr-,-een.

For a thin-slab thickne- ss ' for bet-,,ve--n 10 and mm, the distance between the roller axes has to be onlv more than the roller diameter in order to prevent sharp bending during transportation of the thin C. 0 slab which is at a temperature of approximately 1,10O.C.

At furnace temperatures of approximately 1,300C, the furnace rollers must be watercooled if. thev are to achieve sufficient resistance tO Continuous SLreSS and shelf life. The bottom side of the thin slabs or metal sheets is screened from the hot furnace chamber by the furnace rollers and at the same time cooled when the roller surface temperature is below that of the thin slab or the metal sheet. This considerably 4ncreases the required heating time for thin slabs or metal sheets. This problem can be solved only by considerable expansion (doubling) Of the furnace length.

1"-M4-tz causes very a--.71fa,,-,-)urable.ie---t-4,n,-- and celolingwater consunotion as well as increased investments.

It would be desirable to be able to provide a process and a furnace of said type which does not suffer the indicated problems and wherein a short hiCc!itemperature rolling furnace with a i,,inir--un, number of 1. urnace rollers can be used.

According to the present invention, and.0 increase 'he moment 01 ressiS 'L an C e in order i 1-1 e 'n -- a d 3. material is deformed in proff ile prior to or at entry i -n t o the f urnace, and that t h i s deformation is maintained whilst passing through the furnace. 'L 11 i S.

c establishes the precondition of heating slim materIal -nesses in a hightemperature rolling furnace or thick c C similar furnaces with large distances between rollers or transport beams respectively.

Profile deformation of the heated material can also be removed during or after exiting the furnace. The f- combination of profile-deformation devices in front of and behind the furnace passage permits an increase in c - moment of resistance of the metal sheets whilst passing throu-h the furnace, so that the distance between c rollers in the furnace can be substantially increased, thus permitting virtually even heating of the heated 0 material both from underneath and from the t Furthermore, this deformation of profile makes possible for the heated material to be seated only the area of the lateral edges on the furnace rollers op. it in in a furnace. This reduces the seating surface of the heated material in a furnace and thus improves even heatin- from underneath.

0 Profile deformation between lateral seating surfaces l 0 according to the invention preferably comprises an upwardly oriented curvature. Depending on the de.gree of profile deformation, or curvature of the heated material respectively, the seatin- surface can, according to the invention, also be adjusted by means of axial displacement of the furnace rollers whilst in operation. This allows to limit the acti-,,,e roller support surface in the furnace to a minimum value, and thus a reduction of heat- and cool in,--,-s-,ater requirements.

For practical reasons, the heatinz material with deformed profile is laterally guided in the furnace 4. d u r in its passaze throuLh the furnace bv settlin- means or support rims respectively on the furnace rollers or by separate guide rollers, in order to prevent possible damage to fire-resistant lateral walls and interruption of production.

For carrying out the inventive process, a furnace with top and bottom heating and with especially cooled furnace rollers, which are spaced in the longitudinal direction of the furnace and arranged in the transverse direction Of the furnace for transporting the heated material. is suggested, wherein according to C the invention profile deformation devices are provided in front of or at the furnace inlet and, if appropriate, also in front of or at the furnace outlet. These profile deformation devices can comprise conventional roller systems. Even when using heated materials of a thickness of less than 50 mm, the distance between the furnace rollers can be between 1,000 and 2,000 mm, preferably between 1,000 and 1,500 mm. This also makes possible furnace temperatures of 1,300'C and above, also in roller furnaces.

The invention will now be exemplarily described in more detail, based on the enclosed Figures 1, 2 and 2a.

Shown are, in Fig. 1: a vertical cross-section of a rolling furnace with an arrangement of a thin slab with deformed profile (0); Fig. 2: a perspective view of the arrangemint of a 0 slab (6) with deformed profile on the furnace rollers (2); and Pi-. 2a: outline of the thin slab prior to deform- c ation of profile and after removal of deformation of profile.

5. in Fig. 1. a rolling furnace 1 is equipped with furnace rollers 2 which take up a specified position in the furnace through openings in the lateral walls 3 of the furnace. The respective head distance 4 of the furnace rollers 2 depends on the width of the 'thin slabs or metal sheets with deformed profile, which are to be heated. Only the edge region 7 of the thin slabs 6 is supported by the furnace rollers 2. At maximum permissible width of a thin slab (normal case), only a small portion of the length of a rolling furnace is inside the hot furnace and actively applied. Heat and cooling-water losses are t hu s considerably reduced. According to the invention, the thin slab 5 (see Fig. 2a) is mechanically deformed in profile just in front of the furnace inlet by a suitable deforming device in order to make possible a maximum roller gap. The moment of resistance of a thin slab 6 with deformed profile is considerably higher than that of a plane thiff slab 5. The roller distance can be considerably increased (for example up to an axis distance of 2,000 mm). The bottom side of the thin slabs is then not screened and is not subject to substantial cooling by furnace rollers 2_ which are usually watercooled. The result is virtually twosided heating of the thin slab. The required heating time and the furnace length are thereby optimally. influenced, or reduced respectively. The heat- and cooling-water requirement as well as the number of furnace rollers are reduced to a minimum. Due to the small number of rollers, combined with a simul taneously reduced active roller-support length in a hot furnace, furnaces rollers can be used whi ch have proved themselves for many years. for example in walkin-beam furnaces. in addition thereto, external insulation of these rollers (outside the active support area) is possible. As soon as the thin slab exits the furnace, the profile deformation can be removed by a suitable 6. device which is not illustrated in the Figures, order to facilitate subsequent winding or rolling.

in ihe figures additionally illustrate furnace openings, l.-,hich are designated 8, for the supply of heat below and abo.,,-e the heated material. Drives and mountings 9 of the furnace rollers 2 are movable outside the furnace on wheels 10 in the transverse direction to the oven.

7.

Claims

CLAIMS - heating netallic heated material, 4.n Procl-ss fol, c particular

thin slabs, metal sheets an.dsteel bands, in hi zh-'L e.Mo--ra 'Lure rolli--i- furnaces -with Lop and bottom heatin,-, a n d especially cooled C - - fur-nace rollers arranged in the transverse direction Of the fur-lace for ti-ansporting the c heated material characterised in that 'L In heated material is deformed in profile, which deformation is maintained whil-st passinS t'-rou-,h the furnace, prior to or during entry into the furnace so as to increase the moment of resist- ance.

3:

--Z:

6:

Process according to claim 1, characterised in that the deformation of profile is removed during or after exiting the furnace.

0 Process according 'LO Claim 1, characterised in 0 that the heated material with deformed profile is seated on the furnace rollers inside the furnace only in the area of the lateral ed-ges.

Process accordini to claim 3, characterised in that the deformation of profile bet-,,;---en the lateral seating surfaces is Preferably in the form of an upwardly oriented curvature.

Process according to claim 3, characterised in that the seating surface is also adjustable during operational movements by axial displacement of the furnace rollers.

-"to at least one of clair-iis 1 to P r o c ees s a c c or d'l"fi g.L 5, characterised in that the heated material with deformed profile is laterally guided in the furnace bY settling. means or support rims on the furnace rollers or by separate Suide rollers.

8.

a:

i n f o r c -:. r r y 4, In:g Ou, t p:-o,-ess according to one or several of the abo-,,-e L d ' 7 1 - 11 xi 'h 'op a n d b o o n. lie a - i n- c I -- i r, S e 5 DLe 1 1 a 11 Y c 0 0 1 _ed f 1 - r i - a c r 0 11 e r 5 i c h r a n _sz d n 'L he L: 11- 11 "1 c 0 41 r a n s D o r t i t e 11 e a t e d s-Daced I I t h e 10111 c- i 'L U.d i n a 1 direc-tion 0 f f u, rnac e, characterised in that pro defor.mation devices are arranged in Iront of -,rnace inlet and, Lf appropriate. also Lhe 1 he n; 1 f...

transverse G -- r -- c- 1, -1 co -, 1 0 f n r 1 t z) e a-d fi le J - n f.ont of or at Z u:--.,iac- according that, for t-he i-ise 0 cl-4m 7 of heated or characterised in rz-a'L-,rials of less Lhan -50 mm thickness the distance bet;-;een Lhe, f.-irnace rol lers is 1 000 and 2 preferably be'LTe--n 1.003. and A process for heating ' metallic heated material substantially as described with ref erence to the accompanying drawings.

10: A furnace for heating metallic material substantially as described with reference to and as illustrated by the accompanying drawings.

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