US3502314A

US3502314A - Tiltable crucible or converter for refining pig iron

Info

Publication number: US3502314A
Application number: US686993A
Authority: US
Inventors: Othmar Puhringer
Original assignee: Voestalpine AG
Current assignee: Voestalpine AG; Voest AG
Priority date: 1967-01-17
Filing date: 1967-11-30
Publication date: 1970-03-24
Anticipated expiration: 1987-03-24
Also published as: AT276452B; DE6605749U; DE1583315A1

Description

o. PUHRINGER 3,502,314

TILTABLE CRUCIBLE OR CONVERTER FOR REFINING PIG IRON March 24, 1970 5 Sheets-Sheet 1 Filed Nov. 50, 1967 [NVENTOR OTH MAR PUH RINGER HIS ATTORNEYS March 24, 1970 o. PUHRINGER 5 3 TILTABLE CRUCIBLE OR CONVERTER FOR REFINING PIG IRON 3 Sheets-Sheet 2 Filed Nov. 30, 1967 x 2 a W :mx J f/ V. ll 4 M 9) r 8\ %mungu c k mm 3 .u a I & m 3 V. l'l.

[NVENTOR OTHMAR PUHRINGER HIS AT TORNEYS March 24, 1970 QPUHRINGER 5 3 TILTABLE CRUCIBLE OR CONVERTER FOR REFINING PIG IRON Filed Nov. 30, 1957 3 Sheets-Sheet 3 [NVENTOR OTAAR PUHRINGER HIS ATTORNEYS United States Patent O U.S. Cl. 266-36 7 Claims ABSTRACT OF THE DISCLOSURE A tiltable converter for metallurgical processes is supported from an annular carrying ring by a plurality of brackets, each of which employs an inclined plane bearing surface to allow for thermal expansion. The bearing surfaces are formed between fixed wedges secured to fianges projecting radially from the converter and respective adjustable wedges mounted on both the top and bottom of the carrying ring. The preferred inclination of the bearing surface (to a plane normal to the converter aXis) is substantially equal to the ratio of the distance parallel to the longitudinal axis of the converter between opposed bearing surfaces on top and bottom of the carrying ring, divided by four times the radial distance of a fixed wedge from the longitudinal axis.

Two pairs of upper and lower carrying flanges and one pair of tilting flanges are provided, the former above and below the respective converter trunnions and the latter mdway between the trunnions. Both separate flange segments at each support location and continuous fianges about the converter periphery are disclosed.

The invention relates to a tiltable crucible or converter for refining pig iron, which is supported in an annular carrying ring surrounding the shell of the crucible by means of supporting elements, such as pairs of brackets, -Which take up the bearing stresses. The carrying ring is rigidly connected to two trunnions placed on diametrically opposite sides. The crucible must be tiltable from the substantially vertical blowing position into the upsidedown position for complete discharging and back into the upright position 'by means of electric or hydraulic drives actng on the trunnions.

An important problem in the Construction of crucible or converter assemblies resides in the provision that the high temperatures, -which the crucible shell reaches during operation, do not have any detrimental eflect upon the Construction. In particular, provision has to be made that thermal expansions of the crucible shell and the difference in expansion between crucible shell and refractory lining cannot displace the diametrically opposite trunnions from their coaxial alignment. Furthermore, provision has to be made that n-o dangerous Shock stresses on the converter mounting can be caused as a result of developing clearances.

Various ways of fulfilling this demand have been tried. For instance, converters without carrying rings were built, where the trunnions are mounted directly to the shell by means of joining elements. Although with this construction any clearance in the converter mounting cannot occur, the stresses resulting from thermal expansion cannot easily be accommodated and the inevitable deformations of the vessel find an immediate response in a misalignment of the trunnions. It has also been suggested to build a converter -with a welded-in carrying ring, the carrying ring being designed as reinforced middle part ot the converter and the trunnions being mounted directly ice on the carrying middle part. With this Construction it is also difiicult to securely accommodate the stresses resulting from thermal expansons or from the difference in thermal expansion between refractory lining and carrying shell.

The most robust Construction so far known remains yet a crucible or converter Suspended in a separate structural part, i.e. the carrying ring, which surrounds the shell of the crucible in spaced relatonship, approximately in the height of its center of gravity, and the present invention relates to that kind of a crucible or converter assembly.

With known types of this kind of converter construction, the supporting means taking up the bearing stresses were usually designed as pairs of brackets spaced around the periphery of the crucible shell and engagng the carrying ring by means of a projecting fiange. In the upright position of the crucible, the bearing surfaces define a horizontal plane. When the shell of the crucible reaches a higher temperature during operation, thermal expansion causes a clearance at the unstressed bearing surfaces, because the crucible 'with the brackets mounted thereon expands more than the carrying ring. This causes heavy impact shocks when the crucible is tilted, as the crucible rocks to and fro between upper and lower brackets. The Shock stress resulting from the expansion clearance is extremely detrimental to the whole Construction, especially for the bearings, and it reaches inadmissibly high values with large converters having an output capacity of to 300 metric tons.

To avoid this disadvantage, it has already been suggested to design the bearing surfaces of the lower supporting lugs as inclined planes slanting towards the center of the ring, the inclination corresponding to an angle a, which is defined by the ratio of the distance between upper and lower bearing surfaces divided by the radius of the vessel. This angle oc corresponds to the proportion of axial to radial expanson and would theoretically enable a clearance-free expansion on the lower brackets. In practice, however, such conditions cannot be attained due to the fact that the degree of heating of the crucible surface varies during a crucible campaign. In addition, other deformations and distortions occur apart from the theoretical longitudinal and radial expansion. Practice has shown that stresses having their origin in the fabrication (lamination, weldng) come into effcct during heating of the crucible shell and the carrying ring, which stresses urge for compensation and thereby cause deformations. A consequence thereof are permanent deformations. These deformations do not recede even if the temperature is equalized. For these reasons, the design with an inclination angle x on the lower supporting lugs does not result in the desired clearance-free expansion, but a dangerous jamming occurs, which leads to incalculable increases in the stress on the crucible wall and the carrying ring.

According to U.S. Patent No. 3,337,205, which is based on a similar train of thought, it has been suggested to divide up the theoretical thermal expansion angle oc upon upper and lower brackets so that the bearing surfaces in that Construction are designed with only half the inclination, i.e. oc/ 2. The danger of jamming is already diminished in that Construction.

The present invention relates to a further development and improvement of a crucible mounting having bearing surfaces inclined towards the center of the ring, and has as its object to safeguard a reliable converter suspension even with extreme differences in the temperature distribution. In certain top-blowing processes, such as the LDAC process, the top part of the converter is, as a whole, considerably warmer than the bottom part of the converter. There are also cases where the temperature distribution is reversed, e.g. towards the end of a crucible campaign, when the lining in the bath area is more strongly worn. The bottom part of the converter in the range of the lower brackets then is considerably warmer than the top part. Local radial expansions in the range of the upper and lower brackets, which are larger than the axial expansion, may result from these great differences in temperature. Accordingly, an angle a or even x/Z for the inclination of the bearing surfaces would not be suited for actual Operating conditions. Jammings between brackets and carrying ring may occur, imparting uncontrollable stresses to the whole joining structure.

A further object of the invention resides in that a secure suspension and support of the crucible has to be guaranteed even in the horizontal tilted position. With known constructions it has often happened that shock stresses have resulted from a side clearance developing between the supporting lugs and a stop on the carrying ring.

The construction of the invention, which solves these problems, is characterised according to its main feature in that the inclination of the bearing surfaces is smaller than the ratio H /D, preferably H /2D, wheren H stands for the aXial distance between upper and lower bearing surfaces and D stands for twice the radial distance of the bearing surfaces from the longitudinal axis of the crucible. According to the preferred embodiment, the inclination of the bearing surfaces thus corresponds to an angle of oc/4. These inclined bearing surfaces are provided on the upper as well as on the lower supporting means.

The inclined bearing surfaces are suitably provided on supporting means arranged in pairs, so-called pairs of brackets, of which two pairs of brackets, the supporting bracket pairs, are arranged diametrically opposite substantially in the trunnion axis, and a further pair of a brackets, the tilting bracket pair, is substantially perpendicular to the trunnion axis. According to a modified embodiment of the invention, the inclined bearing surfaces may also be spaeed around a ring-shaped supporting construction surrounding the crucible shell and being fixed thereto, said supporting construction comprising an upper belt, a lower belt, and ribs mounted between these belts, and having disconnecting recesses, if desired.

According to a preferred characteristic of the invention, the inclined bearing surfaces are detachable and adjustable. They may be provided on a pair of wedges, one of said wedges being rigidly welded to the projecting flange of a supporting element or releasably connected therewith by means of a shearing bolt, and the other of said wedges being releasably and adjustably connected with a guide means of the carrying ring. The guide means of the carrying ring comprises a lateral guidance and a radial guidance, the lateral guidance being formed by rails mounted on the carrying ring by means of screws, and the radial guidance comprising a centering shoe which abuts on the carrying ring and has a fixing screw which reaches into the wedge and penetrates fitting plates.

A special characteristic of the invention, which secures the horizontal tilt position of the crucible, resides in the inclined bearing surfaces of each supporting bracket being designed as two pairs of wedges arranged symmetrical of the trunnion aXis, a stopping block being provided between them in a conical recess on the carrying ring, said stopping block being adapted to be centered in relation to the walls of the conical recess of the carrying ring by means of side wedges with fitting plates and fixing screws.

The construction according to the invention combines the advantages of the known constructions without having their disadvantages. The danger of jammings is excluded, while the clearance resulting from the thermal.

expansion keeps within acceptable limits, i.e. sudden shock stresses during tilting are avoided. The weight of the charged crucible or converter is carried by the main supporting brackets in the range of the trunnions, when the crucible is in the erect position. The stress caused by the tilting moment during turning of the crucible is accommodated by the tilting bracket. The theoretical calculation for the bearing of the crucible may thus be based on a three-point support, each of the three points being, for constructional reasons, spread over two adjacent bearing surfaces, which has an advantageous eflect upon the theoretically calculated stresses.

Embodiments of the invention are illustrated in the drawing. FIG. 1 shows a crucible with carrying ring and supporting means in elevation and partly in cross-section. FIG. 2 shows the ground-plan of FIG. 1. FIG. 3 shows a vertical cross-section through a supporting bracket along the line III- III of FIG. 2 on an enlarged scale, FIG. 4 a cross-section along the line lV-IV of FIG. 3, and FIG. 5 is the ground-plan of FIG. 4 along the sectional line V-V of FIG. 4. FIG. 6 shows a cross-section along the line VI-VI of FIG. 1 and demonstrates the mounting of the adjusting wedges for the stopping blocks for accommodating the crucible weight in the horizontal position of the crucible. FIGS. 7 and 8 show elevation and groundplan of a modified embodiment.

Numeral 1 in the drawings denotes the crucible, having a refractory lining 2. A carrying ring 10 surrounds the shell of the crucible; it may consst of several parts, as shown in FIG. 2. The crucible 1 is Suspended in the carrying ring by means of pairs of brackets, pairs of

brackets

4, 4', and 3, 3' being arranged substantially in the trunnion axis and acting as supporting brackets, while the pair of tilting brackets 5, 5' is arranged perpendicular thereto. These three pairs of brackets are of identical design. For constructional reasons, they are designed as pairs of double-brackets. A guide means 6 is arranged diametrically opposite of the pair of tilting brackets, and is designed in known manner for accommodating lateral stresses, but does not abut the carrying ring.

As shown in FIG. 3, each

bracket

3, 3', 4, 4', 5, 5' comprises an upper belt 3a welded to the crucible shell 1, a lower belt 3b welded to the crucible shell, and intermediate ribs 3c welded to the converter shell. Alternatively, a common screw-type connection between brackets and vessel is also possible. A wedge-shaped bearing plate 8 is detachably connected to the lower belt 3b by means of a shearing bolt 7, said plate resting upon a corresponding wedge-shaped counter piece 9 detachably connected to the carrying ring 10. The bearing surfaces of the wedge plate 8 and the counter piece 9 are inclined towards the center of the ring, their inclination being defined by H/2D (FIG. 1), corresponding to an angle of oc/4 according to the previously given definition. The detachable mounting of the counter piece 9 is effected by means of a centering shoe 11 having a nose 11a. Fitting plates 12 are inserted into the gap between nose 11a and counter piece 9. Fixing screws 13 penetrate through bores of the nose part 11a and of the fitting plates 12 into the counter piece 9 and hold it fast against the nose lla.

Rails

14 and 15 are mounted on the carrying ring 10 for lateral guidance of the wedge portion 9 on the carrying ring (FIG. 4), rail 15 being replaceable, so that wedge portion 9 may be laterally dismounted. Rail 15 is fixed to the carrying ring by screws 16.

The mounting support of the crucible for the horizontal tilt position is shown in FIGS. l and 6. The crucible weight is carried by stopping blocks 17, arranged on the supporting brackets between two wedge portions 8 and lying in a recess of the carrying ring, which recess is formed by carrying ring noses 19. As shown in FIG. 6, the recess tapers radially outwardly, i.e. it is conical. Side wedges 18 are laid against the walls of the carrying ring noses 19 on both sides of the stopping block 17, a slight play being adjusted between said wedges and the carrying ring noses 19. Ftting plates 20, inserted between a bridge 21 fixed to the noses 19 and the wedges 18, are provided for adjusting wedges 18. The wedges are held against bridge 21 by means of screws 22.

According to the modified embodiment shown in FIGS.

7 and 8, a continuous supporting bracket ring is provided for reinforcing the whole vessel, said ring comprising an upper belt 23a, a lower belt 23b, and intermediate ribs 23c. The belts and ribs are welded to the crucible shell, disconnecting recesses 23d being provided on the ring, which serve to prevent excessive stresses due to a temperature gradent in the annular belts. In those zones of the crucible shell, which, owing to the relieve apertures, are non-engaged, any excessive stresses which may occur can be reduced by allowing a local flow in the crucible shell. Apart from that, the design of the inclined bearing surfaces as pairs of wedges and also the horizontal support construction are the same as described in connection With FIGS. 1 to 6.

What I claim is:

1. In a tiltable steelmaking converter:

a vessel, substantially circular in cross-section;

a peripheral annular ring having upper and lower walls spaced radially from said vessel;

a number of upper and lower brackets on said vessel having radially projecting flanges extending substantially parallel to said upper and lower walls of said rng;

each flange having at least one fixed wedge secured thereto with an inclined bearing surface facing said annular ring;

a number of complementary adjustable wedges releasably mounted on said upper and lower walls of said ring and having inclined bearing surfaces for engagement With respective bearing surfaces of said fixed wedges;

said fixed and adjustable wedges having engagng bearing surfaces extending at an angle having an inclination substantially equal to the ratio of the axial distance separating the facing bearing surfaces on a pair of fixed wedges Secured, respectively, to an' upper and a lower bracket, divided by four times the radial distance of a fixed wedge from the longitudinal axis of said vessel.

2. In a tiltable steelmaking converter:

a vessel, substantially circular in cross-section;

a peripheral annular ring spaced radially from said vessel and having upper and lower walls;

a pair of trunnions having a common aXis and extending in opposite directions from said annular ring;

two pars of upper and lower carrying brackets on said vessel having radially projecting flanges extending substantially parallel to said upper and lower walls of said ring in the direction of said aXis of said trunnions;

a pair of upper and lower tilting brackets having flanges extendng substantially parallel to said upper and lower walls of said ring in a direction perpendicular to said axis of said trunnions;

each fiange of said carrying and tilting brackets having at least one fixed wedge Secured thereto with an inclined bearing surface facing said annular ring;

said fixed and adjustable wedges having their engagng bearing surfaces extending at an angle having an inclination substantially equal to the ratio of the aXial distance separating the facing bearing surfaoes on a pair of fixed wedges Secured to respective ones of a pair of upper and lower brackets, divided by four times the radial distance of a fixed wedge from the longitudinal axis of said vessel.

3. In a steelmaking converter as recited in claim 2:

a number of guide means on said upper and lower walls of said annular ring for mounting a respective one of said adjustable wedges;

each guide means comprising a pair of rails screwmounted on said ring for lateral guidance of an adjustable wedge, and a centering shoe supported on said ring and holding a fixing screw extending into said adjustable wedge, for radial guidance of said wedge.

4. In a steelmaking converter as recited in claim 2:

two fixed wedges on each flange of each pair of carrying brackets, arranged symmetrically of said trunnion axis and engagng with correspondingly arranged adjustable wedges on said annular ring;

a stopping block mounted on each of said flanges between said two fixed wedges thereof;

said stopping block being inserted in a conical recess of said annular ring and adapted to be centered in relation to said conical recess by means of lateral keys bridged by a connecting member Secured to said keys by fixing screws having fitting plates thereon.

5. In a steelnaking converter as recited in claim 2:

a shearing bolt mounting each fixed wedge on a projecting bracket flange.

6. In a tiltable steelmaking converter:

a vessel, substantially circular in cross-section;

a peripheral ring having upper and lower walls spaced radially from said vessel;

an upper and a lower annular supporting construction rigdly secured to and surrounding said vessel;

each supporting construction comprising a first belt, a second belt extending adjacent to and substantially in parallel with said upper and lower walls of said ring, and a plurality of ribs connecting said belts;

a number of spaced-apart fixed wedges Secured to each second belt, each of said fixed wedges having an inclined bearing surface facing said peripheral ring;

said fixed and adjustable wedges having their engagng bearing surfaces extending at an angle having an inclnation substantially equal to the ratio of the distance separating the engagng bearing surfaces of a pair of axially aligned fixed wedges on respective ones of said second belts, divided by four times the radial distance of a fixed wedge from the longitudinal aXis of said vessel;

said adjustable wedges being mounted on said ring by means of lateral and radial guide members.

7. In a steelrnaking converter as recited in claim 6:

disconnecting recesses on said first and second belts of said supporting constructions adjacent to said vessel.

References Cited UNITED STATES PATENTS 3,l63,696 12/1964 Johansson et al 266-36 3,372,205 8/1967 Puxkandl 266--36 J. SPENCER OVERI-IOLSER, Primary Examiner J. S. BROWN, Assistant Examiner g g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,5 ,3 Dated March 9 Inventor(3) Othmar P'ihringer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line l, "Vereingte" should read --Vereinigte--;

Col. 6, line 64, "3,372,2o5" should read --3,337,2o5--.

SIGNED AND SEALED JUL 41970 Amet:

a M. Fle-wher. Iu I in Office: IIAM E. MHUYLER, JR.

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