US3872914A - Continuous ingot casting machine - Google Patents

Abstract

A continuous ingot casting machine comprising a vessel for molten metal from which metal is positively fed from below through a siphon device into a radial cooled mould wherein an ingot is shaped. To withdraw the ingot upwards use is made of an appliance coupled with a dummy bar and a top part of the descending section of the secondary cooling device. The latter has a radial ascending section with inductors arranged along its length, and a descending section which is similar in shape to a half-ring and is furnished with a drive adapted for reversible rotation of the section about a horizontal shaft passing through the centre of curvature of the secondary cooling device, said descending section of the device being also fitted with rollers with shoulders supporting the ingot. The descending section of the secondary cooling device is followed by mill stand slideways made arcuate with the centre of a radius of curvature coincident with that of the ingot being cast.

Description

baited Mates Patent [191 Korshunov et a1.

[ Mar. 25, 1975 CONTINUOUS lNGOT CASTlNG MAfIHllNiE [76] Inventors: Evgeny Alexeevich Korshunov,

pereulok Otdelny, 5a, kv. 29; Evgeny Zakharovich Freidenzon, ulitsa Lunacharskogo, 161, kv. 23; Mikhail lvanovich Fedorov, ulitsa Komsomolskaya, 72, kv. 27; Konstantin Alexeevich Malikov, ulitsa Komsomolskaya, 59a, kv. 7, all of Sverdlovsk; Nikolai Vasilievich Brazhnikov, ulitsa Gvardeiskaya, 6, kv. l7, Nizhny Tagil; Alexandr lvanovich Kalinin, ulitsa Mira, 12, kv. 49, Nizhny Tagil; Lev Mikhailovich Axelrod, ulitsa Stroitelei, 2, kv. 4, Nizhny Tagil; Mikhail losipovich Arshansky, prospekt Lenina, 23/40, kv. 8, Nizhny Tagil; Vladimir Arkadievich 'lyagunov, ulitsa Mira, 36/7, kv. 3; Oleg Ashotovich Aragilian, ulitsa Kuibysheva, 137, kv. 3, both of Sverdlovsk, all of U.S.S.R.

[22] Filed: Feb. 1, 1974 [21] Appl. No.: 438,662

[52] US. Cl 164/147, 164/270, 164/281,

164/282, 164/283 S [51] Int. Cl ..1B22d 11/12 [58] Field of Search 164/49, 82, 147, 281, 282,

[56] References Cited FORElGN PATENTS OR APPLlCATlONS 265,385 7/1970 U.S.S.R 164/82 Primary ExaminerRobert D. Baldwin Attorney, Agent, or Firm-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A continuous ingot casting machine comprising a ves sel for molten metal from which metal is positively fed from below through a siphon device into a radial cooled mould wherein an ingot is shaped. To withdraw the ingot upwards use is made of an appliance coupled with a dummy bar and a top part of the descending section of the secondary cooling device. The latter has a radial ascending section with inductors arranged along its length, and a descending section which is similar in shape to a half-ring and is furnished with a drive adapted for reversible rotation of the section about a horizontal shaft passing through the centre of curvature of the secondary cooling device, said descending section of the device being also fitted with rollers with shoulders supporting the ingot. The descending section of the secondary cooling device is followed by mill stand slideways made arcuate with the centre of a radius of curvature coincident with that of the ingot being cast.

7 Claims, 9 Drawing Figures PATENTED S sum 2 OF 6 FIE. 2

ll CONTINUOUS INGOT CASTING MACHINE The present invention relates to continuous ingot casting machines and more particularly to radial-type casters.

During the last decade radial and especially curved mould continuous casting machines have found wide application, insofar as they allow casting heavy ingots measuring up to 300 2000 mm in cross section with an up to 2.5 m/min rate of withdrawal of the ingot from.

the cooled mould. Vertical-type casters in common use earlier had not been suitable for the production of such large-size ingots with the above-mentioned casting rates.

Known in the art is a range of radial, curved and annular mould ingot casting machines, those for combined casting and rolling among them.

The machines comprise a vessel for molten metal from which it is admitted into a radial cooled mould whose interior is closed with a dummy bar when the casting process is initiated. The metal ingot shaped in the cooled mould but not completely solidified is passed first into a radial or curved descending part of a secondary cooling device and then either to an ingot dividing means or to a rolling mill.

However, the known radial and curved mould machines do not meet, as yet, up-to-date requirements.

The ingot transfer rates obtainable on the casters are insufficient. Therefore to provide the production rates which are in line with the throughput capacities of modern metallurgical units for the manufacture of molten metal ingot thickness must be increased impractically given the width, with the resulting increase in power consumption during rolling.

But even an enlarged cross-sectional area of the ingots being cast cannot solve fully the problem of achieving the required production rate.

At the rates achievable on the known radial and curved mould machines and large cross sections of the ingots being cast, the straight operation is usually performed on the ingots containing a liquid metal phase, such straightening being objectionable for certain metals since it results in the occurrence of internal defects casting flaws.

Often the ingots produced on the above-mentioned casters do not feature adequate surface quality which is needed for subsequent rolling without preliminary partition which impedes combined casting and rolling.

Lately a method of casting metal ingots has been developed and published, said method envisaging positive underfeed of molten metal into a radial cooled mould with the ingot being periodically pulled up from the mould into a secondary cooling device provided the pressure of molten metal on the ingot crust in the mould zone is changed at regular intervals (cf. Authors Certificate of the USSR no. 265385).

Referring to the drawing illustrating the abovementioned method, a casting machine proposed therein comprises a vessel for molten metal siphoned positively into a radial cooled mould above which, as viewed in the direction of the production process, both an ascending and descending sections of the secondary cooling device are located, said sections being furnished with ingot-supporting rollers, inductors for counterbalancing the liquid metal contained in the ingot being cast with the help of an electromagnetic field prior to ingot withdrawal from the mould, and

with an appliance for pulling the ingot out of the mould at the beginning of the casting operation.

With a comparatively small thickness of the ingots to be cast the above machine is capable of providing the production rate, in tonnage of the ingots being cast, meeting the up-to-date requirements, the quality of the ingot surface being substantially higher than that obtained for the ingots cast on other machines.

However, in casting certain metals even the above machine does not exclude the occurrence of internal defects (flaws) resulting from the straightening of the ingot which contains liquid metal. Moreover, the caster presented in the drawing of the above-mentioned Authors Certificate is furnished with gears for transferring and cooling the ingot being cast on both the ascending and descending sections of the secondary cooling device which are far from being perfect.

The main object of the present invention is the provision of a continuous ingot casting machine suitable for combined casting and rolling and featuring a production rate which would satisfy modern requirements.

Another no less important object of the invention is to provide a continuous casting machine capable of casting ingots free from external and internal defects and suitable for further rolling.

Still another object of the invention is the provision of a compact casting machine which does not require a large production floor.

These and other objects of the invention are achieved by the provision of a continuous ingot casting machine comprising a vessel for molten metal siphoned positively from below into a radial cooled mould which is followed, in the direction of the production process, by a secondary cooling device made up of an ascending and descending sections which are beams mounting ingot-supporting rollers, the ascending section of the secondary cooling device carrying inductors arranged in pairs, and an appliance with a dummy bar for drawing the ingot out of the mould; the secondary cooling device of said machine comprising, according to the invention, a radially curved descending section similar in shape to a half-ring and resting on a horizontal shaft which passes through its centre of curvature, and a gear of a drive for reversible rotation of the section about the shaft, with said inductors being positioned along the entire ascending section of the secondary cooling de vice, and the ingot withdrawal appliance constitutes at least a pair of radial cooled bars manufactured from an electroand heat-conducting metal, each bar being connected with one end to the dummy bar and with another to the top part of the descending section of the secondary cooling device, and provision is made for drives pressing each of said bars against an appropriate lateral side of the ingot.

This machine features a higher production rate as compared to the known similar machines, and cyclic operation, with each cycle being composed of a pause and a withdrawal period.

The caster with the descending section of the secondary cooling device similar in shape to a half'ring is more compact and convenient in service as compared with the known machines; it excludes straining (straightening) of the ingot being cast with a longlength liquid phase contained therein by which virtue the ingot being cast is suitable for combined casting and rolling.

The provision of the inductors arranged along the entire ascending section of the secondary cooling device facilitates the counterbalancing of the molten metal in the ascending branch of the ingot being cast and makes it possible to cool it uniformly in this branch.

The use of the cooled electroand heat-conducting bars in the ascending section ofthe secondary cooling device ensures: initial ingot withdrawal from the mould and an aid in drawing it out under steady melting conditions; the requisite regular cooling of the ingot lateral sides; a reduction in the so-called inductor end effect which contributes to a decrease in inductor installed capacity.

It is expedient that said sets of inductors be so attached to the beams of the ascending section of the secondary cooling device as to provide relative concurrent radial displacement of the mate inductors in each pair in opposite directions and be fitted with drives adapted to perform the above displacement.

Owing to the above transfer and the use of drives for the inductors located in pairs on the radial beams of the ascending section of the secondary cooling device the inductors can be held tightly through cooled shoes to the ingot during the pause between the withdrawals; they ensure also the required regular cooling of the ingot and preclude its bulging owing to metallostatic pressure.

Prior to the ingot withdrawal from the mould when the inductors are energized and the metallostatic pressure dominishes, the inductors are moved aside from the ingot by the drives in a radial direction and do not interfere with the ingot withdrawal from the mould.

It is desirable that some of the radial beams carrying said inductors be mounted rotatably about a horizontal axis, said rotation ensuring reciprocation of the inductors along the arcuated ascending section of the secondary cooling device, and may be equipped with drives for that purpose.

On account ofthe above attachment ofthe inductors to certain of the radial beams the ingot withdrawal is facilitated at the very beginning of the withdrawal pro cess and the ingot is imparted a backward motion immediately after it has been drawn out of the mould by the inductors pressed against it.

For casting ingots ranging in width from 400 to 2000 mm on the machine disclosed herein it is expedient that the top part ofthe descending section of the secondary cooling device be furnished with discs arranged in two rows and adapted to deflect the crust on the ingot being cast from its opposite wide sides, with the discs being mounted on pivots arranged in parallel with the pivotal axis the shaft 6- of the descending section of said device, the discs in the central portion of each row having a larger diameter than that of the extreme discs.

The deflection of the ingot crust is selected so as to preclude the occurrence of hot" flaws resulting from tensile strains.

Due to proper deflection of the crusts on the wide sides of the ingot being cast the metal of the ingot central portion is first to solidify even in the zone of reduced pressure of the liquid metal in the descending section of the ingot being cast, the liquid metal being therefore subdivided along the ingot section into two parts. As soon as two parts of molten metal are separated out in the ingot section, an ingot not more than 1.5-2.0 m wide would aquire a carrying capacity and would not bulge at a rise in pressure of the liquid metal under the effect of metallostatic pressure. Hence, the design of the descending portion ofthe secondary cooling device does not necessitate the use of special elements precluding ingot bulging.

It is desirable that the ingot-supporting rollers in the descending section of the secondary cooling device be fitted with shoulders and positioned radially on ingot lateral sides in such a manner that the ingot weight would be taken up by the shoulders.

This would enable the use of the short ingotsupporting rollers, a reduction in the weight of the descending section of the secondary cooling device and, hence, in the total weight of the machine.

Some of the ingot-supporting rollers in the descending section of the secondary cooling device can be provided with brakes applied during the ingot transfer with each brake constituting a block fastened to the movable element of a longitudinal transfer drive and interacting with the roller side surface.

The brake precludes roller rotation when the de scending section of the secondary cooling device revolves about its pivotal axis when the ingot is withdrawn from the mould. This results in creating through the ingot being cast of an extra force which adds to the ingot withdrawal force.

It is desirable that the descending section of the secondary cooling device be followed in the direction of the production process by a movable roll mill stand with slideways along which said movable stand travels being made arcuate, the centre of the radius of curvature coincident with that of the descending section of the secondary cooling device.

The above arrangement of the movable stand slideways makes it possible to avoid the objectionable straightening of the ingot during combined casting and rolling on the hereinproposed machine, particularly if the ingot entering the movable stand had not solidified completely.

The present invention will be better understood from a consideration of a detailed description of exemplary embodiments of the continuous ingot casting machine thereof, to be had in conjunction with the accompanying drawings, wherein:

FIG. 1 shows the machine according to the invention (a section by a vertical plane through a longitudinal axis);

FIG. 2 depicts inductors with the drives mounted on the beams of the ascending section of the secondary cooling device (a side view with a section in the mould zone);

FIG. 3 section IIIIlI of FIG. 1;

FIG. 4 shows the descending section of the secondary cooling device (a section through a longitudinal axis made by a vertical plane);

FIG. 5 section VV of FIG. 4;

FIG. 6 section VIVI of FIG. 4;

FIG. 7 shows a section of the descending branch of the secondary cooling device of the machine for casting ingots preferably of square section (a view from a convex part of the descending section);

FIG. 8 section VIII-VIII of FIG. 7;

FIG. 9 shows a siphon device with a pneumatic feeder chamber (a longitudinal sectional view).

The machine comprises a vessel 1 (FIG. 1) for molten metal with the vessel outlet connected to the inlet portion of a siphon device 2. The outlet portion of the siphon device 2 is coupled with a radial cooled mould 3 which is mounted stationary.

In this embodiment, the siphon device 2 accommodates an induction pump to be preferable when a metal with a relatively low melting point, as aluminum, is cast on the machine.

In another embodiment of the herein-disclosed machine the siphon device may comprise a pneumatic feeder chamber, as it is shown in FIG. 9. The latter is preferable when casting a metal with a relatively high melting point, such as steel.

To withdraw the ingot from the mould 3 (FIG. 2) provision is made for a dummy bar 4 introduced into the mould from the top and connected through an interlocking element 6 to cooled bars 5 arranged on ingot sides.

The mould 3 is followed in the direction of the production process by an ascending section of the secondary cooling device with inductors 7 (FIG. 1) being positioned in pairs along the entire length of the section. The sets of inductors 7 are separated by supporting rollers 8 also located in pairs.

The number of the cooled side bars 5 (FIG. 2) corresponds to that of the lateral sides of the ingot being cast, i.e., one pair for a single ingot, four bars for two ingors, etc.

The inductors 7 are connected to cross beams 9 adapted to transmit their (inductor) weight to sliding supports 10 set up on radial beams 11 of the secondary cooling device.

Some of the radial beams 11 are made fast, the other ones resting on a shaft 12 (FIG. 1) positioned horizontally at the centre ofa radius of curvature of secondary cooling device. With the aid of a rod of a hydraulic drive 13 some of the beams 11 and inductors 7 are imparted a reversible rotary motion about the shaft 12.

Mounted on the radial beams 11 (FIG. 2) are hydraulic rams 14 with rods 15 coupled with the cross beams 9 through which the inductors 7 forming a pair are simultaneously shifted in opposite directions relative to each other. i

The radial beam 11 carry also hydraulic rams 16 (FIG. 3) whose bifurcated rods 17 are connected to rollers 18 clamping the bars 5 to the lateral sides of the ingot being cast.

The bars 5 are manufactured from an electroand heat-conducting metal. Before the casting process is initiated, each bar 5 is coupled with one end with the dummy bar 4 (FIG. 2), its other end being connected with the top part of a descending branch 19 (FIG. 1) of the secondary cooling device. The bars 5 are connected to the dummy bar 4 only at the beginning of the casting process, and in operation they are coupled with the descending section 19 of the secondary cooling device.

The descending section 19 of the secondary cooling device is similar in shape to a half-ring and is fitted with a toothed sector 20 (FIG. 4) engaging gear 21 of a drive imparting the descending section 19 of the secondary cooling device a reversible rotation about the horizont-al shaft 12.

The halfring ofthe descending section l9of the secondary cooling device comprises longitudinal girders 22 interconnected by cross beams 23 and coupled with a tilting bearing the shaftlZ-through radial beams 24.

Mounted in pairs along the girders 22 are rollers 25 (FIG. 5) positioned radially on the lateral sides of the ingot and fitted each with a shoulder on which the ingot rests.

Where the machine is intended for casting an ingot slab from 400 to 2000mm wide, on the top part of the descending section 19 (FIG. 4) of the secondary cooling device is installed an appliance 26 for deflecting the crusts on the wide sides of the solidifying ingot.

The appliance 26 comprises two cooled spindles 27 (FIG. 6) provided with supports 28 mounted on curved girders 22 and bolted through springs (not shown in the drawing) which enables the dummy bar 5 (FIG. 2) and the end portion of the ingot being cast to be passed through discs 29 of the appliance 26 (FIG. 4).

The spindles 27 mount the discs 29 whose diameters are in agreement with a given deflection of the wide sides of the ingot.

Where the machine disclosed herein is utilized for casting ingot slabs over-400 mm in width, it is sufficient to haveone row of the cooled rollers 25 fixed in pairs (FIG. 5) in boxes 30 into which bushes 31 with shoulders are pressed. The boxes 30 with the rollers 25 are installed intermediate of the slideways which serve also as the cross beams 23.

The boxes 30 in their extreme position are locked by dogs 32. Inserted between the boxes 30 and dogs 32 are blocks 33 adapted to adjust the position of the rollers 25 according to the width of the ingot being cast, taking -into account the deflection of its. solidifying crusts.

Axial displacement of the rollers 25 with the boxes 30 is bounded by strips 34 attached to the cross beams 23.

Some of the rollers 25 are equipped with brakes. each of these comprising a cylinder 35 fastened to the curved girder 22, with the cylinder rod 36 being connected to a brake shoe 37 which is pressed against the roller 25 when braking is effected.

If the caster is designed for the production of ingots of square or rectangular cross-section up to 400 mm wide, a plurality of such ingots can be cast on the machine simultaneously, by making use of a single vessel for molten metal 1 (FIG. 1), one siphon device 2 and a unit mould assembly 3 with the required number of strands.

In this case the ascending section of the secondary cooling device shall be made with due regard for the fact that a plurality of ingots and several pairs of bars 5 are to be moved therealong, and the descending section 19 is provided with several rows of the rollers mounted in pairs with the roller number varying with that of the strands of the mould 3.

This exemplary embodiment is illustrated in FIGS. 7 and 8 wherein is shown a part of the descending section of the secondary cooling device of the machine for casting ingots, preferably of square cross-section (FIG. 7 is a view from the convex side of the descending section) with two rows of twin rollers 25 (FIG. 8). To reduce the width of the descending section 19 the sets of rollers 25 are arranged so that a plane passing through the axes of one set of the rollers is spaced apart from that passing through the axes of the rollers of the adjacent set at a distance not less than the diameter of the shoulder 38 of the roller 25 and that one of the rollers in the set would not contact the ingot passing between the rollers of another set or pair.

Irrespective of the number of the ingots being withdrawn a reversing drive 39 with the toothed sector 20 is arranged on the convex side of the descending section of the secondary cooling device.

At the end of the descending section of the secondary cooling device is installed a movable roll mill stand 40 (FIG. I) which is able to travel along slideways 41 made arcuate with the centre of a radius coincident with the centre of curvature of the mould and of the.

secondary cooling device, and located on the horizontal shaft 12.

After the slideways 41 of the roll mill stand 40 a delivery table 42 and shears 43 for severing the ingot being cast are provided. v

If the machine is equipped with the siphon device 2 (FIG. 1) wherein an induction pump is substituted by a pneumatic feeder chamber 44 (FIG. 9), the chamber is positioned intermediate of an inlet header 45 adapted to feed molten metal and an outlet header 46 which serves for discharging the molten metal, both headers 45 and 46 being provided with metal pipes through which the chamber 44 communicates with the vessel 1 (FIG. 1) and mould 3.

The inlet header for feeding the molten metam may be fitted with either one or a plurality of metal pipes which may be provided, if required, with heating means.

The inlet header 45 has a hole 48 through which the metal or slag remaining in the pneumatic feeder chamber are tapped, the hole being sealed with a plug 47.

The pneumatic feeder chamber 44 is furnished with a perforated detachable cover 49 which mounts a stopper 50 with a hydraulic (or pneumatic) drive 51 and a cooling chamber 52 supporting the drive 51.

The cooling chamber 52 incorporates a sealing means 53 made as a bellows to keep gas from leaking from the pneumatic feeder chamber 44 through a gap between the lining of the cover 49 and stopper 50.

Connected to one of the openings in the cover 49 is a branch pipe 54 running to a system which serves for supplying compressed gas, preferably inert, into the chamber 44.

The continuous ingot casting machine operates in the following manner.

Molten metal 55 is fed into the vessel 1 (FIG. I) from which it flows through the siphon device 2 into the mould 3.

When the casting process is initiated the dummy bar 4 (FIG. 2) fitted with a through hole is introduced into the top portion ofthe mould 3. The metal 55 is supplied into the mould 3 positively with the help of a pneumatic feeder (FIG. 9) or an induction pump accommodated in the siphon device 2 (FIG. I) the metal being fed until it comes into contact with the lower end of the dummy bar provided with a dovetail.

At the beginning of the casting process, as the metal is admitted into the mould 3, air contained in the mould space escapes along the through hole in the dummy bar 4 (FIG. 2).

The molten metal 55 supplied into the mould 3 is maintained there under a pressure of 3-6 atm. until a crust 56 (FIG. 1) of a requisite thickness is formed on the ingot 57. I

A requisite pressure within the molten metal 55 in the zone of the mould 3 is created either with the help of the induction pump set up in the siphon device 2 (FIG. I) or by feeding compressed gas. preferably inert, into the chamber 44 ofthe pneumatic feeder (FIG. 9) mounted in this case in the siphon device 2 (FIG. I)

instead of the induction pump. As the gas is supplied under pressure into the chamber 44 (FIG. 9) of the pneumatic feeder the inlet hole is closed with the stopper 50.

After the crust on the ingot has reached the requisite preset thickness, the pressure in the molten metal 55 of the ingot being cast in the zone of the mould 3 is reduced to a value which is a function of the height of a column ofthe molten metal 55 in the vessel 1 (FIG. I). This is effected by reducing the pressure of the molten metal in the passage of the induction pump. Where a siphon device 2 with a pneumatic feeder is employed, the drop in pressure is obtained by varying the gas pressure under metal meniscus in the pneumatic feeder chamber 44 (FIG. 9).

Owing to a drop in pressure within the molten metal 55 of the ingot 57 being cast, the ingot crust 56 can be easily withdrawn from the mould 3.

At first the ingot is drawn out of the mould 3 with the aid of the dummy bar 4 (FIG. 2) and side bars 5 connected each with one end to the dummy bar 4 and with the other to the top part of the descending section 19 (FIG. 1) of the secondary cooling device.

By bringing the descending section 19 of the secondary cooling device into rotation about the shaft 12 the ingot 57 is quickly withdrawn from the mould 3 with the required amount of the molten metal 55 being concurrently fed positively into the mould through the siphon device 2. At this stage the pressure of the molten metal 55 in the passage of the induction pump of the siphon device 2 or that below the metal meniscus in the pnuematic feeder chamber 44 (FIG. 9) should be maintained at such a level that an adequate supply of metal into the mould 3 is provided during the withdrawal period.

At the initial moment when the ingot is drawn out of the mould 3 the hold-drawn rollers 18 (FIG. 3) are taken aside from the side bars 5 and are not in the way of the element 6 interlocking the side bars 5 with the dummy bar 4 (FIG. 2) when the above element 6 passes by the rollers 18.

The side bars 5 do not deviate from a pre-set direction, since they are coupled with the dummy bar 4 (FIG. 2) and the top part of the descending section 19 (FIG. 1) and because special guide slots are provided for them in the rollers 8.

Prior to the withdrawal of the ingot from the mould 3 the hydraulic rams 14 draw the inductors 7 (FIG. 2) apart in radial directions until they rest against the strips provided on the sliding supports 10, whereupon the hydraulic ram 13 moves them aside from the mould at a distance which is a function of the backward motion of the ingot 57 (FIG. I) which in turn depends upon ultimate shrinkage of different portions of the crust 56 being formed on the ingot in the zone of the mould 3.

The inductors 7 being drawn apart prior to the withdrawal of the ingot from the mould, the ingot can be subsequently readily displaced with respect to the shoes, preferably cooled ones, attached to the inductors 7 to protect inductor winding from the heat of the ingot 57 being cast.

Upon extracting a pre-set section of the ingot amounting to about -95 percent of the length of the mould 3, the'inductors 7 and side bars 5 are held tight to the ingot in the zone of the cast ingot, the latter being imparted the above mentioned backward motion.

This is effected with the help of the drive of the descending section 19 of the secondary cooling device and under the effect of weight of the inductors 7.

At the same time the pressure within the liquid metal of the ingot 57 being cast is built-up to a pre-set value either through the use of an induction pump or gas pressure in the pneumatic feeder chamber, the moulding of the next portion of the ingot being therefore initiated under stationary conditions.

Then comes a pause an interval between two withdrawals of the ingot from the mould 3. At the beginning of the pause the side bars are returned into their initial position by rotating the descending section 19 (FIG. 1) of the secondary cooling device to place it into the original position, the side bars being detached from the dummy bar by the interlocking element 6 (FIG. 2) prior to their return into the initial position. To this end it is sufficient to depress an arm of the element 6 which does not take part in subsequent operation of the machine.

As soon as the side bars 5 (FIG. 2) are set to their original position, the hydraulic rams 16 (FIG. 3) hold them tight to the ingot through the roller 18.

On completion of the pause between the ingot withdrawals, after the next portion of the solifidying ingot crust 56 has reached the preset thickness, the withdrawal cycle is repeated, with the ingot being again extracted from the mould 3. In this case, as in the preceding one, the solidifying ingot crust 56 is relieved in the zone of the mould 3 from the pressure exerted by the liquid phase. This is achieved by varying the pressure of the molten metal in the siphon device 2 (FIG. 1).

However, insofar as the ingot is pulled from the mould 3 upwards and the core of its withdrawn portion contains nonsolidified liquid metal, to preclude the backflow of the molten metal into the vessel 1 (FIG. 1) at a drop in pressure in the siphon device which may cause the formation ofa blowhole in the ingot, the molten metal is counterbalanced with the aid of an electromagnetic field induced in the ingot being cast by the inductors 7 pressed against the ingot and energized at this instant.

The next withdrawal operation on the ingot is first effected due to frictional forces originating between the ingot and side bars 5 and inductors 7 forced against it when they wre transferred along the'arc by the drive 39 of the descending section 19 (FIG. 1) and hydraulic drive 13 (FIG. 2). Next after the inductors 7 have been driven along the are a small distance which depends upon the distance to the rollers 8 (FIG. 1), and are. hence, moved aside from the ingot, the latter is transferred owing to the frictional forces between the side bars 5 (FIG. 3) and the ingot and to electromagnetic forces induced in the crust of the ingot being withdrawn by the inductors 7 which are energized at this moment.

During the transfer of the side bars in the coarse of ingot withdrawal from the mould 3 they are first forced by the first (the nearest to the mould) opposed pairs of hydraulic rams 16 (FIG. 2) against the ingot through the rollers 19 (FIG. 3), but as soon as the element 6 (FIG. 2) approaches the rollers 18, the hydraulic rams 16 will move them (the rollers 18) aside from the side bars and let the element 6 pass by.

The need to move the first pair of opposed rollers 18 aside from the side bars is also caused by the fact that during the ingot withdrawal the side bars 5 come out of the action zone of the first pair of the rollers 18.

Where the length of the ingot extracted from the mould 3 during the first withdrawal operation is insufficient to enable its withdrawal from the mould under the effect of frictional forces, the design of the side bars 5 provides for the installation of the second and even third element for interlocking the side bars 5 with the dummy bar 4.

During all subsequent withdrawal of the ingot from the mould 3 the metal is fed therein through the siphon device 2 (FIG. 2). In this case if the siphon device 2 is equipped with a pneumatic feeder, then upon counterbalancing the liquid phase of the ingot after the mould 3 the stopper 50 (FIG. 9) is lifted by the drive 51 and a new portion of the molten metal is supplied into the chamber 44 from the vessel 1 (FIG. 1).

When the stopper 50 is hoisted (FIG. 9) the bellows 53 is extended and air-tightness of the chamber 44 is not disturbed.

To preclude failure of the bellows 53 under the effect of hot gases, it is constantly cooled from the exterior, the coolant being continuously fed into the cooling chamber 52.

The volume of the metal fed into the chamber 44 (FIG. 9 prior to the withdrawal of the ingot 43 from the mould 3 (FIG. 1) shall be concordant with that supplied to the mould 3 over the ingot withdrawal period.

To cut down the time period required for feeding metal from the vessel 1 (FIG. 1) into the pneumatic feeder chamber 44 (FIG. 9) the inlet header 45 may be fitted with a plurality of metal pipes with several stoppers 50 being in that case set up in the pneumatic feeder chamber 44.

As the ingot being cast proceeds. along the ascending section of the secondary cooling device, the second and the next sets of the inductors 7 (FIG. 1) mounted in that zone are actuated. I

Electric energy is fed to the inductors 7 not during the entire ingot casting time but only when the weight of the molten metal contained in the ingot being cast must be counterbalanced after the mould in the ascending section and during the withdrawal of the ingot from the mould 3. During the remaining time which amounts to about -80 percent of the total time the inductors 7 are de-energized.

Having passed the ascending section ofthe secondary cooling device the ingot enters the zone ofthe descending section 19 (FIG. 1) and is advanced intermittently resting on the shoulders of the rollers 25 (FIG. 6).

In casting ingots with the maximum side width of 400 mm the appliance 26 (FIG. 4) for deflecting ingot wide sides is not installed on the half-ring 19. In this case preference shall be given to the simultaneous casting of several, for example, two ingots 57 (FIG. 7) which are concurrently withdrawn from the unit mould assembly 3 (FIG. 1) to pass. the descending section 19 ofthe secondary cooling device also at the same time.

Relative intermittent displacement of the ingot 57 along the descending section 19 is performed in the following manner.

In the course of withdrawal of the ingot 57 (FIG. I) from the mould I the descending section 19 (FIG. 4) is turned about the shaft 12 through the toothed sector 20 and driven gear 21 being shifted along an are at a distance which is equal to the length of the ingot portion being withdrawn from the mould. In this case the rollers 25 are not brought into rotation, some of them being braked and forced against the ingot with the help of the hydraulic cylinder 35 (FIG. This adds to ingot withdrawal force.

When the descending section 19 returns into its initial position, all the rollers 25 are in rotation rolling over with respect to the ingot which is stationary at this moment.

If an ingot being cast is more than 400 mm in width, it can bulge at the end of the descending section 19 of the secondary cooling device under the effect of metallostatic pressure of the molten metal. To prevent this an appliance 26 (FIG. 4) for deflecting the crust being formed on the wide sides of the ingot being cast is mounted in the top part of the descending section 19 of the secondary cooling device.

After the ingot being cast has been admitted into the zone of the descending section 19 (FIG. 1), each time as the section returns into its original position the appliance 26 deflects the solidifying crust 56 to a pre-set value. A profile of the deflected wide ingot crust is chosen so as to prevent the occurrence of hot flaws resulting from tensile strains.

The deflection of the wide sides of the ingot being cast ensures complete solidification of the ingot central portion even before it (the ingot) enters the zone of an increased metallostatic pressure in the descending section 19 of the secondary cooling device.

On complete solidification of its central thinned portion, the relatively wide ingot 57 being cast (FIG. 5) is now capable to resist the bulging effect of the metallostatic pressure.

As the ingot proceeds along the descending section 19 (FIG. 1) of the secondary cooling device, the width of the sections of the ingot 57 (FIG. 5) with a molten core diminishes gradually and that of the crust 56 of the ingot 57 increases, a feature which also precludes ingot bulging at the end of the descending section 19 (FIG. 1) of the secondary cooling device.

Upon passing the descending section of the secondary cooling device the ingot enters the roll mill stand 40 (FIG. 1) where it is rolled down to a given thickness.

During rolling the stand 40 travels in the slideways 41 made arcuate with the centre of a radius of curvature coincident with that of the secondary cooling device. The above transfer of the roll mill stand 40 does not require the straightening of the ingot 57 prior to rolling and enables an ingot with not yet solidified portions to be rolled without any defects, since it obviates elongation of metal layers at the boundary of the solidification zone.

Where an ingot 57 with a core which has not yet solidified is fed into the roll stand 40, first the lateral sides of the ingot and only then the entire ingot cross-section are reduced by the rolls.

Owing to the use ofthe movable roll mill stand 40 the ingot being cast can be rolled without correlating the rolling and withdrawal speeds.

When the ingot is being withdrawn from the mould 3 the roll mill stand 40 (FIG. 1) is shifted in the direction of movement of the ingot together with the latter.

At the end of the casting process prior to the last withdrawal of the ingot from the mould, the ingot tail portion is subjected to a more intense cooling, the ingot being extracted after a solidified crust has formed on its end portion. This precludes the ingress of the molten metal from the tail portion of the ingot crust when it is transferred in the mould zone and in the ascending section of the secondary cooling device.

Usually characteristic of the ingots produced on the known continuous casting machines are considerable pipes formed in the tail portions of the ingots due to shrinkage which diminishes materially the yield.

On the caster according to the present invention the pipes are avoided. For this purpose at the end ofoperation of the caster, the ingot being cast but already disconnected from the mould shall be transferred with such a speed that it would be delivered to the rolling mill with a core which has not yet solidified. This makes it possible to displace a certain fraction of the molten metal into the non-solidified part of the ingot during the rolling process and, hence, to make up for the shrinkage.

Open supply of cooling water is not practized in the ascending section of the secondary cooling device, the ingot being cooled through the cooled inductors shoes and side bars in this zone.

As to the descending section of the secondary cooling device, any most suitable and commonly known secondary cooling appliance can be used therein.

Main advantage of the continuous casting machine disclosed herein, ie high production rates, enhanced quality of an ingot being cast and compact design, result from the following.

The machine is designed for cyclic operation, each cycle being composed of a pause and withdrawal period.

The production rate of the casting machine depends on the mould length and duration of the pause. The duration of the withdrawal period is a function of the withdrawal rate and mould length changing negligibly when the latter are varied and having thereby small influence on the production rate of the caster.

Insofar as a mould of considerable length (ranging from l.5 to 2.0 m) can be used on the caster and the duration of the pause which is necessary for the crust to reach the required thickness can be very small, amounting for instance to l0-6O s., a high average rate of transfer of the ingot being cast and, hence, high production rates are attainable.

The production of ingots with enhanced surface quality is attributed to the fact that the initial formation of the ingot crust in the mould zone is effected under pressure.

Sound internal structure of the ingot is ensured because though the ingot being cast on the proposed machine may have a liquid phase of a considerable length which is dependent on the radius of curvature of the secondary cooling device, the ingot containing notsolidified molten metal is not subjected to straightening and if such an ingot with a non-solidified core is reduced, the process is carried out so as to preclude the origination in the solid-liquid part of-the ingot of hazardous tensile stresses which are one of the causes of internal flaws.

The compact design of the caster is ensured due to practically annular arrangement of all the mechanisms. The secondary cooling device adopted for the machine differs in its design from conventional devices, its merit being a small weight. The above device is equipped with a range of compact, preferably hydraulic, drives and with only one main drive of the half-ring of the descending branch of the secondary cooling device, the

weight of machinery of such casting machines being thus negligible.

What we claim is:

1. A continuous ingot casting machine, comprising: a vessel for molten metal; a siphon device which has an inlet portion connected to said vessel, and an outlet portion; a radial cooled mould whose lower end is open to the outlet portion of said siphon device; a secondary cooling device located after said mould in the direction of the production process and comprising ascending and descending sections which are beams to which ingotsupporti'ng rollers are secured with said descending section being curved radially, similar in shape to a halfring and resting on a horizontal shaft passing through its centre of curvature; a drive for reversible rotation of said descending section of the secondary cooling device about said horizontal shaft, said drive being fitted with a gear on which said descending section of the secondary cooling device rests; inductors arranged in pairs along the entire length of the ascending section of said secondary cooling device; an appliance adapted for ingot withdrawal from said radial cooled mould, comprising a dummy bar and at least a single pair of radial cooled bars made from an electroand heat-conducting metal and connected at the beginning ofthe withdrawal operation with one end to the dummy bar and with the other to the top part of the descending section of said secondary cooling device; drives pressing each of said bars against the lateral side of the ingot being cast.

2. A machine ofclaim 1, wherein said sets of pair inductors are so secured to said beams of the ascending section of the secondary cooling device as to allow concurrent relative radial displacement of one inductor with respect to another in opposite directions, and provision is made for drives adapted to perform the above displacement.

3. A machine of claim 1, wherein some of the beams carrying said inductors are mounted rotatably about a horizontal shaft which ensures reciprocation of said inductors along an arcuated ascending section of said secondary cooling device, and provision is made for drives adapted to perform the above reciprocation.

4. A machine of claim 1, wherein arranged in two rows in the top part of the descending section of said secondary cooling device are discs deflecting the crust of the ingot being cast from its opposite wide sides with discs being mounted on pivots arranged in parallel with said pivotal axisthe shaftof the descending section of the secondary cooling device, the middle portion of each row comprising discs of a larger diameter than that of the extreme discs of each row.

5. A machine of claim 1, wherein the descending section of said secondary cooling device is furnished with said ingot-supporting rollers provided with shoulders and positioned radially on the lateral sides of the ingot so that its weight is taken up by the shoulders of said rollers.

6. A machine of claim 5, wherein some of said ingotsupporting rollers are furnished with brakes actuated during ingot transfer, each brake constituting a shoe fastened to the movable member of the longitudinal transfer drive and interacting with the side surface of said roller.

7. A machine of claim 1, wherein the descending section of said secondary cooling device is followed in the direction of the production process by a roll mill stand mounted in radial slideways whose geometrical centres of radii of curvature coincide with that of the descend ing section of said secondary cooling device.

Claims (7)

1. A continuous ingot casting machine, comprising: a vessel for molten metal; a siphon device which has an inlet portion connected to said vessel, and an outlet portion; a radial cooled mould whose lower end is open to the outlet portion of said siphon device; a secondary cooling device located after said mould in the direction of the production process and comprising ascending and descending sections which are beams to which ingotsupporting rollers are secured with said descending section being curved radially, similar in shape to a half-ring and resting on a horizontal shaft passing through its centre of curvature; a drive for reversible rotation of said descending section of the secondary cooling device about said horizontal shaft, said drive being fitted with a gear on which said descending section of the secondary cooling device rests; inductors arranged in pairs along the entire length of the ascending section of said secondary cooling device; an appliance adapted for ingot withdrawal from said radial cooled mould, comprising a dummy bar and at least a single pair of radial cooled bars made from an electro- and heatconducting metal and connected at the beginning of the withdrawal operation with one end to the dummy bar and with the other to the top part of the descending section of said secondary cooling device; drives pressing each of said bars against the lateral side of the ingot being cast.

2. A machine of claim 1, wherein said sets of pair inductors are so secured to said beams of the ascending section of the seCondary cooling device as to allow concurrent relative radial displacement of one inductor with respect to another in opposite directions, and provision is made for drives adapted to perform the above displacement.

3. A machine of claim 1, wherein some of the beams carrying said inductors are mounted rotatably about a horizontal shaft which ensures reciprocation of said inductors along an arcuated ascending section of said secondary cooling device, and provision is made for drives adapted to perform the above reciprocation.

4. A machine of claim 1, wherein arranged in two rows in the top part of the descending section of said secondary cooling device are discs deflecting the crust of the ingot being cast from its opposite wide sides with discs being mounted on pivots arranged in parallel with said pivotal axis- the shaft- of the descending section of the secondary cooling device, the middle portion of each row comprising discs of a larger diameter than that of the extreme discs of each row.

5. A machine of claim 1, wherein the descending section of said secondary cooling device is furnished with said ingot-supporting rollers provided with shoulders and positioned radially on the lateral sides of the ingot so that its weight is taken up by the shoulders of said rollers.

6. A machine of claim 5, wherein some of said ingot-supporting rollers are furnished with brakes actuated during ingot transfer, each brake constituting a shoe fastened to the movable member of the longitudinal transfer drive and interacting with the side surface of said roller.

7. A machine of claim 1, wherein the descending section of said secondary cooling device is followed in the direction of the production process by a roll mill stand mounted in radial slideways whose geometrical centres of radii of curvature coincide with that of the descending section of said secondary cooling device.

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