EP3848133A1

EP3848133A1 - Apparatus and process for producing metal bars through continuous casting

Info

Publication number: EP3848133A1
Application number: EP21151431.0A
Authority: EP
Inventors: Carmelo Maria BROCATO; Flavio REGGIANI
Original assignee: GMS Global Metallurgical Solutions Srl
Current assignee: ENGITEC TECHNOLOGIES SpA
Priority date: 2020-01-13
Filing date: 2021-01-13
Publication date: 2021-07-14
Anticipated expiration: 2041-01-13
Also published as: EP3848133B1; IT202000000457A1; EP4316691A2; EP4316691A3; EP3848133C0

Abstract

The apparatus (10) for producing metal bars through continuous casting comprises a chain of lower die halves (3) and an upper closure system (5) in turn comprising a die-closing belt (9) which in the rectilinear casting stretch (13), closes the lower die halves (3) at the top. The apparatus (10) further comprises a first direction change support (23). The points of rest of the die-closing belt (9) against the first direction change support lie substantially along a resting surface having an average radius of curvature (RC1, RC2) equal to or greater than 0.5 metres and which is substantially tangent to the path followed by the die-closing belt (9) along the rectilinear casting stretch (13). This reduces the stress and wear of the belt (9) and the casting channel (7) is closed with a better tightness.

Description

Field of the invention

The present invention relates to an apparatus and a process for producing metal bars through continuous casting, particularly suitable for producing bars of aluminium and alloys thereof and other non-ferrous metals.

Background

Machines for producing bars of non-ferrous metals through continuous casting, in which the casting die is formed by a chain of lower die halves closed at the top by a metal belt are currently known.
An example of such continuous casting machines is described in the Japanese patent application No. JP58020356 in the name of Mitsubishi Heavy Ind LTD, in which the reference number 4 indicates each of the die halves that are connected to form a chain closed on itself, and the reference number 3 indicates the belt closed on itself which closes the casting channel in the casting stretch at the top.
According to the authors of the present invention, this type of continuous casting machine has however several drawbacks.
The closure belt undergoes considerable mechanical stresses, in particular to fatigue, since the rollers on which it slides have a small diameter.
This causes premature belt wear and breakage, making machine maintenance and operating costs worse.
In the zone closest to the crucible, the casting channel is closed with poor tightness, which causes leakages of molten metal between the lower die halves 4 and the die-closing belt 3.
These leakages in turn encrust and generally foul the machine, cause misalignment of the lower die halves 4 and malfunctions in general.
In some examples and models of this type of continuous casting machine, the problems of tightness between the belt 3 and the lower die halves 4 also occur in the central stretches of the casting channel.
It is an object of the present invention to obviate the above-mentioned drawbacks of the prior art and in particular to provide an apparatus for producing metal bars through continuous casting having an improved tightness against leakages of molten metal.
Another object of the present invention is to provide an apparatus for producing metal bars through continuous casting, the die-closing belt of which is less stressed and subject to wear and failures.

Summary of the invention

This object is achieved, according to a first aspect of the present invention, with an apparatus having the features according to claim 1.
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, the first direction change support (23) comprises a pulley, wheel or roller which are configured to rest against the die-closing belt (9) during normal operation of the continuous casting apparatus (10) and having a diameter of one meter or more.
In a particular embodiment of the invention, the apparatus (10) comprises a second direction change support (25) for deviating the die-closing belt (9) in a second stretch of its path, wherein the second direction change support (25) may comprise, for example, a pulley, wheel or roller.
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, the die-closing belt (9) is arranged to advance by travelling along the second roller conveyor stretch (TR2) after having travelled the first roller conveyor stretch (TR1).
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, the portion of the casting stretch (13) in which the casting path (TRC) is substantially concave can possibly extend for a length equal to or greater than half the overall length of the casting stretch (13); in this case the portion of the casting stretch (13) in which the casting path (TRC) is substantially concave can possibly extend for a length equal to or greater than three quarters, four fifths, nine tenths of the overall length of the casting stretch (13) or it can extend over the entire overall length of the casting stretch (13).
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, the portion of the casting stretch (13) in which the casting path (TRC) is substantially concave extends for a length equal to or greater than 5 metres, or equal to or greater than 6 metres, 7 metres, 8 metres, 9 metres; in this case, the portion of the casting stretch (13) in which the casting path (TRC) is substantially concave may extend for a length equal to or lower than 15 metres, or 12 metres, 10 metres, 8 metres.
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, one or more of the first nozzles (41) is/are arranged to strike with a jet of air or other cooling and/or cleaning gas the die halves (3) at least at a first part of the casting stretch (13) at or near the casting zone (11).
In a particular embodiment of an apparatus for producing metal bars through continuous casting according to the invention, one or more of the second nozzles (43) is/are arranged to strike with a jet of water or other cooling and/or cleaning liquid the die halves (3) and/or the die-closing belt (9) at least at a second part of the casting stretch (13) downstream of the first part of the stretch of the casting channel (13) .
In a particular embodiment of the invention, the apparatus (10) comprises one or more third nozzles (45), each of which is arranged to strike with a jet of water or other cooling and/or washing liquid a part of the lower die halves (3) at the return stretch.
In a second aspect of the invention, this object is achieved by using said apparatus having the features according to claim 16.
In a third aspect of the invention, this object is achieved with a process having the features according to claim 17.
Further features of the invention are the subject matter of the dependent claims.
The advantages attainable with the present invention shall become more readily apparent, to the person skilled in the art, from the following detailed description of some particular, non-limiting examples of embodiments, illustrated with reference to the following schematic figures.

List of Figures

Figure 1 shows a first perspective view of an apparatus for producing metal bars through continuous casting according to a first particular embodiment of the present invention;
Figure 1A shows a side view of the first direction change support of the apparatus of Figure 1 ;
Figure 1B shows a perspective view of a detail of the belt-presser of the apparatus of Figure 1 ;
Figure 2 shows a second perspective view of the apparatus of Figure 1 ;
Figure 3 shows a perspective view of a stretch of the chain of the lower die halves and of the casting stretch of the apparatus of Figure 1 ;
Figure 4 shows a side view of the stretch of the chain of the lower die halves and of the casting stretch of Figure 3 ;
Figure 5 shows a section of the casting stretch of the apparatus of Figure 1 , according to the sectional plane V-V;
Figure 6 shows a section of the casting stretch of the apparatus of Figure 1 , according to the sectional plane V-V;
Figure 7 shows a schematic side view of the cooling system and possibly also washing system of the apparatus of Figure 1 ;
Figure 7A shows a schematic side view of a detail of an apparatus for producing metal bars through continuous casting according to a second particular embodiment of the present invention;
Figure 7B shows a schematic side view of a detail of an apparatus for producing metal bars through continuous casting according to a third particular embodiment of the present invention;
Figure 8 shows a partially sectional view, taken along the sectional plane VIII-VIII, of a point of the return stretch of the chain of the lower die halves of the continuous casting apparatus of Figure 1 ;
Figure 9 shows a front view of an apparatus for producing metal bars through continuous casting according to a fourth embodiment of the present invention;
Figure 9A shows a front view of the downstream belt-presser of the continuous casting apparatus of Figure 9 ;
Figure 9B shows an enlarged detail of the casting die of the continuous casting apparatus of Figure 9 ;
Figure 10 shows a front view of the system for reducing the leakages through the chain of lower die halves of an apparatus for producing metal bars through continuous casting according to a fifth particular embodiment of the present invention;
Figure 11 shows a front view of the system for reducing the leakages through the chain of lower die halves of an apparatus for producing metal bars through continuous casting according to a sixth particular embodiment of the present invention;
Figure 12 shows a front view with a detail of the leakage reduction system of Figure 11 or 12 ;
Figure 13 shows a front view with an indication of the geometric tolerances of the trajectory of the chain of the die halves in the casting stretch in the leakage reduction system of Figure 11 or 12 ;
Figure 14 shows a perspective view of the cutting station of the apparatus of Figure 1 ;
Figure 15 shows a perspective view of a mechanical belt-presser arm of the apparatus of Figure 9 ;
Figure 15A shows a side view, partially in section, of the mechanical arm of Figure 15 ;
Figure 16 shows a partially exploded perspective view of a first example of a crucible usable in the continuous casting apparatus of Figures 1 , 2 or 9 ;
Figure 17 shows a side view of the crucible of Figure 16 , according to a normal direction of observation to the casting axis;
Figure 17 shows a side view, according to a normal direction of observation to the casting axis, of a second example of crucible usable in the continuous casting apparatus of Figures 1 , 2 or 9 .

Detailed description

Figures 1-7 , 8 relate to an apparatus for producing metal bars through continuous casting according to a first particular embodiment of the invention, indicated with the overall reference 10.
In the present description, the terms "top, bottom, above, below, horizontal, vertical" when not otherwise specified refer to a condition of normal installation and operation of the casting apparatus 10.
The continuous casting apparatus 10 can be arranged to cast bars of non-ferrous metals, such as aluminium and alloys thereof, the cross-sections of which have a height ranging, for example, between 10-100 millimetres, and a width ranging, for example, between 10-250 millimetres.
The apparatus 10 comprises a continuous casting die 1 in turn comprising a plurality of lower die halves 3 arranged in succession the one after the other and an upper closure system 5.
Each lower die half 3 forms the bottom 70 and the flanks 71 of a casting channel stretch 7, is open on the flank opposite to the side of the bottom of the respective casting channel stretch 7 and at the ends adjacent to the die halves 3 immediately preceding and following the die half 3 considered.
The casting channel 7 can be substantially inclined with respect to the horizontal (Figures 1 , 1A, 2 , 7 ) or can also be substantially horizontal.
Each lower die half 3 is preferably made of copper, AISI steel or other stainless steel.
Preferably, each lower die half 3 is adapted to contain from 0.5 kg or 0.7 kg to 16 kg or 20 kg of aluminium, preferably from 3 to 7 kg, even more preferably substantially 5 kg.
As shown in the accompanying figures 2 , 4 and 5 , the lower die halves 3 can have a substantially H-shaped (Figure 3 ) or U-shaped cross-section.
The lower die halves 3 are preferably arranged one after the other so as to form a chain preferably closed on itself, which in turn forms the casting channel 7 formed by the succession of recesses of each lower die half 3.
The molten metal coming for example from a crucible 28, 28' can then be cast in the casting channel 7.
Two consecutive lower die halves 3 are preferably fixed together so as to be articulated and to be able to rotate the one with respect to the other.
The closed chain formed by the lower die halves 3 is arranged to slide by making the plurality of lower die halves 3 advance along a path closed on itself.
This closed path, preferably downstream of the crucible 28, 28' or other casting zone 11, forms a casting stretch 13 with a shape for example rectilinear in which the casting channel stretches 7 of at least part of the lower die halves 3 are aligned along a common casting axis, that is for example - but as explained below, not necessarily - substantially rectilinear (Figure 1 , 2 ).
In the casting zone 11 the molten metal material is cast into the casting die 1.
The casting zone 11 may also not comprise the crucible 28, 28' but for example comprise only a nozzle, spout or other adapter fed from a crucible not shown and outside the casting apparatus 10.
The path of the lower die halves 3 downstream of the casting stretch 13, for example rectilinear, changes direction so as to detach, in a preferably progressive manner, the lower die halves 3 from a metal bar formed by the metal that has solidified in the casting for example rectilinear stretch 13.
As is visible in Figure 1 , the apparatus 10 comprises a first 15 and a second die advancing wheel 17, against which the chain formed by the lower die halves 3 rests or around which the chain is wound.
The wheels 15, 17 are preferably arranged at or near a respective end of the casting for example rectilinear stretch 13 so that at the end of the casting for example rectilinear stretch 13, the chain of lower die halves 3 changes direction around the first die advancing wheel 15, and changes direction again at the second die advancing wheel 17 where it will reach the casting zone 11.
Each link of the chain of the lower die halves 3 preferably comprises a lower die half 3 and a pair of connecting bars 30, preferably substantially parallel to each other and with respect to the casting channel stretch 7 and each fixed on a flank of the respective lower die half 3 (Figure 4 ).
The connecting bars 30 are fixed the one to the other preferably by means of a plurality of lateral pins 4 so as to form two chains arranged side by side and parallel to each other.
Each lateral pin 4 fixes two connecting bars 30 and two adjacent lower die halves 3 one to another, articulating them and allowing the connecting bars to rotate with respect to each other and the lower die halves to rotate with respect to each other, thus forming the aforesaid chain of die halves 3.
The apparatus 10 preferably further comprises a load-bearing frame 27, 27' comprising, for example, a plurality of steel bars and/or plates welded together.
The load-bearing frame 27, 27' is preferably arranged to rest on a floor or on a suitable foundation plinth, possibly made of PRM concrete (Figure 9 ).
The load-bearing frame 27, 27' may comprise, for example, two or more uprights 29, 31, 270 and two or more crosspieces 38, 100, 101 which extend in a more or less horizontal direction, connect two or more of said uprights and are fixed thereto, for example welded or bolted (Figure 1 , 1B, 9 ).
At least along the casting stretch 13, the concavity of the die halves 3 forming the casting channel 7 is preferably turned upwards (Figure 4 ).
The continuous casting apparatus 10 further comprises an upper closure system 20 in turn comprising a die-closing belt 9 made of metal material, for example of steel, and closed on itself.
The die-closing belt 9 can have a width ranging, for example, between 5-25 centimetres or between 16-18 centimetres.
At the casting for example rectilinear stretch 13, the die-closing belt 9 closes a part of the lower die halves 3 on the side opposite to their bottoms of the respective stretches of the casting channel, so as to ensure the tightness of the molten metal during its travel in the casting channel.
The die-closing belt 9 in the more upstream stretch of the casting for example rectilinear stretch 13, or at or near the casting zone 11, describes a first direction change stretch.
The closure system 20 further comprises a belt pressing system 21, shown in Figure 1 , arranged to press the die-closing belt 9 against the open flanks of the lower die halves 3 at at least part of the casting for example rectilinear stretch 13.
The apparatus 10 is provided with a first direction change support 23 placed at the first direction change stretch of the die-closing belt 9 and at or near the casting zone.
The support 23 is arranged to rest against the die-closing belt 9 and guide it along the first direction change stretch so that, at the exit of the latter, it advances in a direction different from that in which it advances at the entry to the first direction change stretch.
The first direction change support 23 is arranged so that the directions with which the die-closing belt 9 reaches and leaves the first support 23 form between them an angle α [alpha] preferably equal to or lower than 120°, more preferably equal to or lower than 90°, more preferably equal to or lower than 60°, more preferably equal to or lower than 30°, and even more preferably substantially equal to 0° (Figure 7A).
Preferably, the closure system 20 further comprises a second direction change support 25 for deviating the die-closing belt 9 in a second stretch of its path.
This second direction change support 25 is preferably a wheel (Figure 1 ), pulley or roller.
The second direction change support 25 is arranged so that the directions with which the die-closing belt 9 reaches and leaves the second support 25 form between them an angle β [beta] preferably equal to or lower than 120°, more preferably equal to or lower than 90°, more preferably equal to or lower than 60°, more preferably equal to or lower than 30°, and even more preferably substantially equal to 0° (Figure 7B).
Preferably along its trajectory, the die-closing belt 9 rests and winds around the first direction change support 23, then runs toward the second direction change support 25 around which it winds itself, afterwards it runs again toward the first support 23, closing its own path on itself.
Preferably, the apparatus 10 is arranged to causing the chain of the lower die halves 3 and the die-closing belt 9 to advance one integral with another and without mutual sliding, at least along the casting stretch 13.
The points of rest of the die-closing belt 9 against the first direction change support 23 - and preferably also against the second direction change support 25- lie substantially along a surface having a finite minimum radius of curvature; this surface is preferably and substantially with single curvature.
This minimum radius of curvature is preferably equal to or lower than 1.5 metres, 1 meter, 0.8 metres or 0.6 metres.
This minimum radius of curvature is preferably equal to or greater than 0.3 metres, or 0.5 metres or 0.6 metres.
The points of rest of the die-closing belt 9 against the first direction change support 23 - and preferably also against the second direction change support 25- lie substantially along a surface preferably with a single curvature having a minimum radius of curvature preferably equal to or greater than 0.5 metres and which is substantially tangent to the path followed by the die-closing belt along the casting for example rectilinear stretch.
As an alternative or in combination with the above, the rotation axes of the rollers or other rolling bodies of the first 23 - and preferably also against the second direction change support 25- can lie substantially in a surface preferably with single curvature having a minimum finite radius of curvature, preferably equal to or greater than 0.5 metres and which is substantially tangent to the path followed by the die-closing belt along the casting stretch 13.
This minimum radius of curvature is preferably equal to or lower than 1.5 metres, 1 meter, 0.8 metres or 0.6 metres.
This minimum radius of curvature is preferably equal to or greater than 0.3 metres, or 0.5 metres or 0.6 metres.
As an alternative or in combination with the above, the rotation axes of the rollers or other rolling bodies of the first 23 - and preferably also against the second direction change support 25- can lie substantially in a surface with an overall arched shape (Figure 1A), possibly in the form of a spiral arc.
Thanks to these wide radii of curvature, the mechanical stress to which the die-closing belt 9 is subjected during operation is reduced, reducing the risks of mechanical stress, breakage, wear and tear thereof and extending its operating life in general.
In a particular embodiment, the first 23 and/or the second direction change support 25 each comprise a pulley, a wheel or roller which is arranged to rest against the die-closing belt 9 during normal operation of the continuous casting apparatus 1 and having a diameter equal to or greater than one metre.
Like for example shown in Figures 1 and 6 , the first direction change support 23 advantageously comprises a roller conveyor in turn comprising at least three direction change rolling bodies 108 arranged to rest against the die-closing belt 9 during normal operation of the continuous casting apparatus 1, wherein such rolling bodies may be, for example, wheels, pulleys or rollers (Figure 1A).
The rolling bodies 108 are arranged so that a same point of the die-closing belt 9, when advancing, rests in succession and not simultaneously against the first, then against the second and then against the third of said rolling bodies 108, and more generally, rests in succession and not simultaneously against only one of said rolling bodies 108 at a time.
The rotation axes of the various rolling bodies 108 are preferably parallel or in any case placed side by side with each other, preferably parallel or in any case placed side by side with the surface of the belt 9 and perpendicular, or in any case transverse, to the trajectory of the belt 9.
Each rolling body 108 has a diameter preferably equal to or greater than 5 centimetres, and more preferably equal to or greater than 8 centimetres and for example ranging between 5-40 centimetres, between 7-20 centimetres, between 8-15 centimetres or equal for example to 8 centimetres.
The roller conveyor 23 is preferably provided with at least 5 rolling bodies 108 for each metre of length of the stretch of belt that rests against the same roller conveyor, more preferably it is provided with at least 8 rolling bodies 108/metre and even more preferably it is provided with at least 10 rolling bodies 108/metre.
The roller conveyor 23 is preferably provided with about 8-20 rolling bodies 108/metre or with 10-15 or with 10-13 rolling bodies 108/metre.
The roller conveyor 23 allows to apply a greater and more uniform pressure on the die-closing belt 9 so as to push it against the edges of the lower die halves 3, improving the tightness between the belt 9 and the lower die halves 3, near the casting zone 11, in which zone the pressure of the molten metal is greater and therefore the risk of leakages thereof from the casting die through slits or other zones with imperfect tightness is greater.
In addition, the roller conveyor 23 allows the belt closing rollers to rest along the casting channel 7 immediately downstream of the roller conveyor 23.
Advantageously, the roller conveyor 23 or other first direction change support 23 is arranged to press the die-closing belt 9 against the lower die halves 3 so as to close the casting channel 7 at the top along the casting stretch 13.
For this purpose the roller conveyor 23 is fixed to the load-bearing frame 27, 27' - for example to the upright 29 formed by this frame - so as to be able to adjust its height above the die-closing belt 9 by varying the force with which it presses the latter.
For this purpose, the rolling bodies 108 are preferably mounted on a respective support, fixed to the load-bearing frame 27, 27' so as preferably to be able to adjust their position with respect thereto.
The roller conveyor 23 can be possibly fixed to the load-bearing frame 27, 27' - for example to the upright 29 - so as to be able to adjust its horizontal position, for example to adjust the tension of the die-closing belt 9.
The roller conveyor 23 is preferably arranged to guide the die-closing belt 9 along a first stretch TR1 having a first minimum radius of roller conveyor curvature RC1 and a second stretch TR2, travelled by the belt 9 directed toward the casting zone 11 after having travelled the first stretch TR1, having a second minimum radius of curvature RC2 substantially lower than the first radius of roller conveyor curvature, for example equal to or lower than 0.9 times or 0.8 times the radius of curvature RC2.
For example, the first radius of curvature RC1 can be about 0.6 metres whereas the second radius of curvature RC2 can be about equal to 0.5 metres.
In this way the radius of curvature of the die-closing belt 9 is kept high over a longer length of its path, reducing it only where necessary, for example for reasons of encumbrance; the mechanical stress to which the die-closing belt 9 is subjected during operation is thus further reduced, reducing the risks of breakage, wear and tear thereof and extending its operating life in general.
Advantageously, the second direction change support 25 is fixed to the load-bearing frame 27, 27' - for example, to the upright 270 formed by said frame - preferably but not necessarily so as to be able to adjust its horizontal position, for example to adjust the tension of the die-closing belt 9, and/or its height above the die-closing belt 9 for example to vary the force with which it presses the latter downwards.
For this purpose, the continuous casting apparatus 10 can be provided with a rotating arm 250 - possibly fixed to the upright 270 or more generally to the load-bearing frame 27, 27'- and with an actuator 252 - such as for example a hydraulic or pneumatic cylinder -, the second direction change support 25 can be fixed to the rotating arm 250 and the latter can be actuated by the actuator 252.
Advantageously, the first 23 and the second direction change support 25 are fixed to the load-bearing frame 27, 27' so as to be able to adjust their horizontal and/or vertical position independently of each other, in particular, they are not mechanically rigidly constrained the one to the other or made integral the one to the other.
In other words, the first 23 and the second direction change support 25 can adjust their position relative to the load-bearing frame 27, 27' and/or between them by moving with respective degrees of freedom substantially that are independent of each other.
In particular, the first 23 and the second direction change support 25 are not fixed to the same common beam.
More generally, preferably the second support 25 is arranged to adjust its position - for example its horizontal position - with respect to the first support 23, so as to adjust the tension of the die-closing belt 9 and thus close the casting channel 7 with better tightness and reduce the mechanical and fatigue stresses of the belt 9.
Advantageously, the apparatus 10 is provided with a liquid and gas cooling system 40, for example air and water.
This cooling system 40, schematically illustrated in Figure 5-7 , comprises one or more first nozzles 41, each of which is arranged to strike with a jet of air or other cooling gas, cooling them, the lower die halves 3 at at least one portion of the casting for example rectilinear stretch 13.
The first nozzles 41 are preferably arranged to flush with a jet of air or other cooling gas the lower die halves 3 at the more upstream portion of the casting for example rectilinear stretch 13 (Figure 7 ).
This more upstream portion preferably comprises or coincides with the so-called hypercritical casting channel stretch, i.e. with the stretch of the casting channel 7 in which the treated metal is still in the molten state (Figure 7 ).
Hypercritical stretch means, in the present definition, the most upstream casting channel stretch in which a metal skin that is thick enough to render a cooling with jets of water at high pressure unadvisable has not solidified outside the bar of the cast metal yet; such jets could in fact break the skin and the water could penetrate in the molten metal creating various drawbacks, among which micro- and macro-explosions which then leave small craters and voids in the solidified metal bar.
More precisely, the expression hypercritical stretch refers to the most upstream stretch of the casting channel in which a metal skin whose thickness is equal to or lower than 0.2 millimetres, more preferably equal to or lower than 0.3 millimetres, more preferably equal to or lower than 0.5 millimetres, more preferably equal to or lower than 1 millimetre has not solidified outside the bar of the cast metal yet.
In combination with or as an alternative to the previous definition, hypercritical stretch can be understood in the present description as the more upstream stretch of the casting stretch having a length ranging between 0.3-1 metre or between 0.3-0.8 metres or between 0.3-0.6 metres.
The nozzles 41 are arranged so as to strike the lower die halves 3 from the bottom and from both sides, right and left with respect to the casting axis.
The air emitted by the nozzles 41 can be for example at room temperature or colder than room temperature, for example 10-20°C lower than room temperature.
Air cooling at or near the casting zone 11 is advantageous compared to water cooling, since in this zone it is particularly difficult to tightly close the casting channel 7, and water that has penetrated into it might adversely affect the casting of molten metal in the casting die.
The preventive cooling by air or other cooling gas allows to reduce the thermal shock of lower die halves 3, allowing in general a better control of their temperature.
The cooling system preferably further comprises one or more second nozzles 43, each of which is arranged to strike with water or other cooling and/or cleaning liquid a part of the lower die halves 3 and/or the die-closing belt 9 at at least the casting for example rectilinear stretch 13.
In particular, the second nozzles 43 are arranged so as to strike with jets of water or other cooling and/or cleaning liquid the lower die halves 3 at least at the casting for example rectilinear stretch 13, downstream of the first nozzles 41 and/or in such a way as to strike with water jets - preferably from above - the die-closing belt 9.
The second nozzles 43 are preferably arranged so as to strike with jets of water or other cooling and/or cleaning liquid the face of the die-closing belt 9 turned towards the outside of the casting channel 7.
The lower die halves 3 are preferably flushed with water or other cooling and/or cleaning liquid from the bottom and from both flanks, right and left, with respect to the casting direction.
Preferably, the second nozzles 43 are arranged so as to flush with water or other cooling and/or cleaning liquid the die-closing belt 9 along at least 70% of the casting for example rectilinear stretch.
More preferably they strike the belt 9 along at least 90% of the casting for example rectilinear stretch, and even more preferably along the entire casting stretch.
Preferably, the second nozzles 43 flush the mould-pressing belt 9 in the hypercritical stretch with water substantially at room pressure - for example because it simply drips onto the belt 9- or with water at relatively low pressure, for example equal to or lower than 2 relative bars, more preferably equal to or lower than 1 relative bars or 0.5 relative bars, thus reducing the risk of water infiltration in the molten or in any case hot metal.
Advantageously, the second nozzles 43 spray or in any case flush the mould-pressing belt 9 outside the hypercritical stretch with water substantially at high pressure, for example at a pressure equal to or greater than 3 relative bars or 4 relative bars, so as to cool more effectively not only the belt but also the metal bar cast underneath it.
These second nozzles 43 are arranged so as to strike with a jet of water or other cooling and/or cleaning liquid the lower die halves 3 along at least 30% or 40% of the casting for example rectilinear stretch, or in any case the lower die halves 3 which are not in the hypercritical stretch of the casting stretch 13.
More preferably, said second nozzles 43 strike the lower die halves 3 along at least 60% of the casting for example rectilinear stretch.
Preferably, the first nozzles 41, and more generally the apparatus 10, is arranged to cool the lower die halves 3 by means of air jets, bringing them to a temperature preferably ranging between 10-60°C, more preferably ranging between 10-40°C, or between 15-25°C and even more preferably between 25-28°C at least in the half - and more preferably at least in the fourth - of the casting stretch 13 closest to the casting zone 11.
The apparatus 10 preferably further comprises a plurality of fixed sliding supports 8 fixed to the load-bearing frame 27, 27' so as to preferably form two rows substantially parallel to each other or in any case placed side by side.
These fixed sliding supports can be fixed, for example, to two beams or crosspieces 47, placed side by side and parallel the one to the other, which can extend along the casting channel 7 between the first 15 and the second die advancing wheel 17 (Figure 3 , 4 ).
Along these fixed sliding supports 8 the chain of the lower die halves 3 can slide and can rest thereon, at least in the casting stretch 13.
Each fixed sliding support 8 may comprise, for example, a roller such as, for example, a bush 80 fitted on a pin 82 so as to be able to rotate thereon (Figures 4 , 5 ), possibly with the interposition of a ball bearing (not shown).
Each bush 80 is arranged to rotate about itself about an axis perpendicular to the direction of advancement of the die halves 3.
Preferably, at least along the casting stretch 13, the lower die halves 3 - and more preferably the respective pair of connecting bars 30- rest on and slide along the fixed sliding supports 8.
This makes maintenance easier and improves efficiency. In fact, carrying out the necessary check operations on a limited number of bushes will be easier and can be scheduled, thus guaranteeing the efficiency of the sliding plane between supports 8 and links 30.
At least along the casting stretch 13, the concavity of the die halves 3 which form the casting channel 7 is preferably turned upwards (Figure 4 ).
Advantageously, the chain of the lower die halves 3 comprises a plurality of advancement projections 6, each of which is arranged to engage with the first 15 and/or the second die advancing wheel 17, preferably engaging with suitable recesses and/or with suitable teeth obtained on the wheels 15, 17.
Each advancement projection 6 preferably comprises a bush 60 fitted on a pin 62 so as to be able to rotate thereon (Figures 4 , 5 ), possibly with the interposition of a ball bearing (not shown).
Each bush 60 is arranged to rotate about itself about an axis perpendicular to the direction of advancement of the die halves 3.
For this purpose at least one of the wheels 15, 17 is preferably a drive wheel.
Again for this purpose, preferably even if not necessarily only one of the wheels 15, 17 is preferably a drive wheel, while the other wheel 17, 15 is idle.
Each advancement projection 6 is preferably arranged at or near half the length of a respective connecting bar 30 (Figures 3 , 4 ), although in an embodiment not shown it can also be arranged at or near an end of such a connecting bar 30.
The advantage of this arrangement is twofold, kinematic and functional.
Kinematic because it reduces the motion irregularity by 50% (arc meshing on a circle); functional because even if also the advancement projection 6 wears, there are no problems of meshing on the wheels 15 and 17.
Preferably, the advancement projections 6 and the fixed sliding supports 8 are arranged on and project from both the right and left flanks, with reference to the casting axis, of the chain of the lower die halves 3.
Each pair of advancement projections 6 and of fixed sliding supports 8 is advantageously obtained from two respective pins which do not extend over the whole width of the respective lower die half 3 or over the whole width of the relative chain link of the die halves 3 (Figures 5 , 6 ).
For this purpose, each pair of advancement projections 6 and of fixed sliding supports 8 is not, for example, obtained from a single through pin which passes through the entire width of the respective lower die half 3 or the entire width of the relative chain link of the die halves 3.
In this way, on the lower face of each die half 3 - with reference to the orientation in space that said die half 3 has in the casting stretch 13- it is possible to obtain a longitudinal groove 110, even quite deep, which can face directly onto the nozzles 41, 43 and be struck with greater power by the air and water jets emitted therefrom, without being partially sheltered by the aforesaid through pins, improving the effectiveness of cooling and washing of the die halves 3 (Figure 5 , 6 ) .
The stretch of the chain of the die halves 3 below the casting stretch 13, i.e. the stretch of the chain of the die halves 3 which extends from the end of the casting channel 7 to the casting zone 11, is conventionally referred to, in the present description, as the so-called return stretch 32 of the chain of the die halves 3.
In the return stretch 32, the chain formed by the lower die halves 3 advantageously follows a convex path - for example in the form of a catenary curve - the convexity of which is turned downwards (Figure 1 ), so as to open and widen - for example, by opening them substantially into a V - the slits formed by the ends of the pairs of die halves 3 adjacent to each other, causing any scraps and incrustations of molten material outflown from said slits to fall down and allowing a better washing of said ends of the die halves 3.
This washing can be made, for example, by means of fluid - for example water or air - at high pressure.
Advantageously along this return stretch 32 the chain of the die halves 3 - preferably the advancement projections thereof 6 - rest on and slide along a pair of sliding guides (not shown) preferably fixed to and integral with the load-bearing frame 27, 27'.
Since these sliding guides support most of the weight of the chain of the die halves 3, they allow to size said chain so that it has a lower tensile strength and therefore a lower weight.
These sliding guides preferably have a shape so that the chain of the die halves follows the aforementioned convex path.
Preferably, the belt-presser 21 of the closure system 20 comprises a plurality of pressers 35, 35', each of which is arranged to rest against the die-closing belt 9 and press it against the lower die halves 3 at least in the casting stretch 13 so as to close the casting channel 7 (Figure 1A , 5 , 6 , 7 ).
Each presser 35, 35' may comprise a skid or more preferably a rolling element such as for example a wheel or a roller (Figure 1A, 15 , 15A ).
In fact, a rolling element runs with less friction on the die-closing belt 9, tends to jam less and raise the belt 9 less, generally creating less drawbacks than a belt-presser skid.
Preferably, the belt-presser 21 of the closure system 20 further comprises a plurality of mechanical arms 37, 37' to each of which a respective presser 35, and possibly one or more respective pressers 35, 35', is fixed so as to be able to move it/them.
Each mechanical arm 37, 37' advantageously comprises an articulated quadrilateral or pantograph kinematic mechanism 374, 374', which allows the relative presser 35, 35' or the relative pressers 35, 35' be raised and simultaneously moved laterally outside the vertical of the belt 9, to allow operators to access the zone below the pressers (Figure 1B, 9 , 15 ).
This feature is extremely useful when carrying out maintenance, belt disassembly and cleaning, or even simply for allowing a visual inspection of the status of the components.
This visual inspection and maintenance interventions can be carried out directly on the casting stretch 13 of the chain of the die halves with no need to carry them out on the return stretch 32, therefore outside the pit 52 which is usually located below the continuous casting apparatus 10, thus keeping operators in a much safer and more comfortable position and allowing a faster maintenance.
The pit 52 can be arranged, for example, to collect the washing or cooling wastewater, lubricating oil and dirt that has come off the apparatus 10, 10'.
Each mechanical arm 37, 37' - in particular its articulated quadrilateral - can be driven by a respective actuator 39, for example by a pneumatic or hydraulic cylinder.
Preferably, all the mechanical arms 37, 37' are fixed to a same substantially rigid element of the load-bearing frame 27, 27', as shown for example in Figures 1 , 1B, 9 .
For this purpose, all the articulated quadrilaterals or pantographs of the arms 37, 37' can be fixed on a same first beam 38 and all the respective actuators 39 to a second beam 100.
The first beam 38 and the second beam 100 preferably extend substantially horizontally and/or parallel or longitudinally to the casting channel 7 in the casting stretch 13.
Each mechanical arm 37' advantageously comprises one or more first roller holder supports 370, to each of which three pressure rollers 35' are fixed.
These rollers 35' are preferably fixed on a respective support 370 so that, when the mechanical arm 37' is lowered or in any case presses against the die-closing belt 9, one of these rollers 35' can rest near and/or at a first edge of the die-closing belt 9, while the other two rollers 35' can rest near and/or at the second edge of the die-closing belt 9.
More particularly, one of said rollers 35' is advantageously arranged to press the first edge of the die-closing belt 9 against the upper edge of a first flank 71 of a casting channel stretch 7, while the other two rollers 35' are advantageously arranged to press the second edge of the die-closing belt 9 against the upper edge of the second flank 71 of the same casting channel stretch, wherein the first and second flank 71 extend parallel or in any case side by side with each other.
Each mechanical arm 37' advantageously comprises one or more second roller holder supports 372, to each of which a plurality of first roller holder supports 370 is fixed so that the latter are aligned according to the direction of the blankholder belt 9.
Each second roller holder support 372 may have, for example, the more or less approximate shape of a crosspiece (Figure 15 , 15A ).
Each second roller holder support 372 is preferably fixed to and actuated by a relative articulated quadrilateral or pantograph kinematic mechanism 374, 374' so as to move the rollers 35' close to and away from the belt 9 according to a predetermined direction, for example according to a vertical direction (Figure 15 , 15A ).
Advantageously, each first roller holder support 370 is fixed to the relative second roller holder support 372 by means of a flexible joint 376, which allows the first support 370 to vary its inclination and orientation in space with respect to the second roller holder support 372: this allows each set of three rollers 35' of a first roller holder support 370 to rest against the blankholder belt 9 contacting and pressing all the three against the belt 9, thus better pressing the belt 9 against the row of lower die halves 3 and thus avoiding the leakage of molten metal between the belt 9 and the die halves 3 or in any case greatly reducing the risk thereof, thus considerably increasing the tightness.
The flexible joint 376 may be, for example, a ball joint.
Advantageously, each flexible joint 376 is provided with a shock absorber in turn provided with a guide rod 3760 and with an elastic element 3762, such as for example a helical spring (Figure 15A ).
The guide rod 3760 is arranged to constrain the relative movements between the first 370 and the second roller holder support 372, for example limiting this movement substantially to a translation.
The elastic element 3762 is arranged to transmit and dampen the thrust of the first roller holder support 370 on the second roller holder support 372 and the contrary reaction thrust preventing the rollers 35' from hitting or pressing with excessive force the belt 9, damaging it.
In order to eliminate or in any case reduce the leakage of liquid metal between the die-closing belt 9 and the die halves 3, the apparatus 10, 10' is advantageously provided with a downstream belt presser indicated with the overall reference 54 (Figure 9A).
The downstream belt presser 54 preferably comprises a carriage 540 provided with wheels or rollers with which it presses the die-closing belt 9 by rolling thereon.
The carriage 540 is positioned near the wheel, pulley or roller 25.
The carriage 540 can be fixed to one or more levers 542, 543 or other kinematic mechanisms and from said lever, levers or kinematic mechanisms pressed against the belt 9.
The levers 542, 543 are preferably actuated by one or more suitable actuators 544, 546.
Advantageously, one or more of said levers 542, 543 is/are hinged to the rotation axis of the wheel, pulley or roller 25.
This allows the carriage 540 to be arranged very close to the wheel, pulley or roller 25, improving the tightness between the belt 9 and the die halves 3 also near the wheel, pulley or roller 25.
In order to eliminate or in any case reduce the leakage of liquid metal between the slits that are present between two adjacent lower die halves 3 along the casting channel, the continuous casting apparatus 10 can be advantageously arranged so that the lower die halves 3 travel, in the casting stretch 13, along a substantially concave casting path TRC with concavity turned downwards; the casting path TRC is indicated by a dotted line in Figures 10 , 11 .
The casting path TRC advantageously comprises an arc of circumference (Figures 10 , 11 ).
The casting path TRC in the casting stretch 13 may be, for example, exclusively concave.
Alternatively, the casting path TRC of the die halves 3 in the casting stretch 13 may comprise a more central stretch in the form of an arc of circle or in any case more generally concave, and one or two convex (Figure 10 ) and/or rectilinear (Figure 11 ) end stretches.
The arc or in any case concave path TRC extends preferably along the whole casting stretch 13, that is preferably from the point of the path of the die halves 3 immediately downstream of the crucible 28, 28' or other casting zone 11 to the point of the path of the die halves 3 in which the now solidified casting of molten metal starts to peel off from the die halves 3.
Alternatively, the concave stretch of the casting path TRC may extend, for example, from the point of the path of the die halves 3 immediately downstream of the crucible 28 or other casting zone 11 and a point placed before that in which the now solidified casting of molten metal begins to peel off from the die halves 3.
In a further alternative, the concave stretch of the casting path TRC may extend, for example, from a point of the path of the die halves 3 not immediately downstream of the crucible 28, 28' or other casting zone 11 and the point in which the now solidified casting of molten metal starts to peel off from the die halves 3.
The position of fixed sliding supports 8 can be suitably selected and/or adjusted to realise these shapes of the casting path TRC; in particular, for this purpose, the rollers or other fixed sliding supports 8 are advantageously mounted so as to be able to adjust in height the position of their rotation axes.
Conventionally, in the present description, the maximum depth PRTMAX of the concavity of the casting path TRC is meant to indicate the maximum distance of a point of the casting path TRC from a tangent straight line TGT - indicated by a dashed line and two dots in Figure 10 - to the casting path TRC at the ends of the casting stretch, wherein this distance PRTMAX is measured perpendicularly to the straight line TGT (Figure 10 ).
The distance along the straight line TGT of its two points of tangency with the casting path TRC is instead conventionally defined as the length LTR of the casting path TRC.
Preferably during normal operation the maximum depth PRTMAX is comprised between 0.5-10 millimetres or between 1-6 millimetres, between 2-4 millimetres or between 3-4 millimetres.
Preferably the maximum depth PRTMAX is comprised between 0.0001-0.0015 times the length LTR, and more preferably it is comprised between 0.0002-0.0008 times, between 0.0004-0.0006 times or between 0.0003-0.0005 times the length LTR.
The length LTR can be for example comprised between 3-10 metres, between 5-9 metres, between 6-8 metres or between 7-8,5 metres.
When the casting path TRC of the die halves 3 in the casting stretch 13 can comprise a more central stretch in the form of an arc of circle, this arc has a radius preferably ranging between 2000-8000 metres, more preferably between 3000-5000 metres or between 3500-4000 metres or between 3800-4200 metres.
The concavity of the casting path TRC of the die halves 3 tends to rotate slightly the various lower die halves 3 around the lateral pins 4, closing at least partially and considerably reducing - indicatively up to half of their through section - the slits 302 present between the end faces 300 that are facing and opposed of two adjacent die halves 3, and consequently considerably reducing the leakage of molten metal between consecutive die halves 3 and the dimensions of the ribs formed by them on the flanks of the bars or ingots of the cast and then solidified metal (Figure 12 ).
These slits 302, designed with very marked dimensions and not to scale in Figure 12 , are present because of the clearances of the chain formed by the lower die halves 3.
This relative rotation of two lower die halves 3, one with respect to another, caused by the concavity of the casting path TRC, can be all the more reduced the more the clearances of the chain of the die halves 3 are reduced, for example, a rotation γ [gamma] of less than 0.3-0.2 sexagesimal degrees, a sexagesimal degree, 0.07-0.04 sexagesimal degrees or 0.06-0.04 sexagesimal degrees may be sufficient.
Preferably, the curvature of the casting path TRC and the rotation γ [gamma] are such as to bring one or more pairs of end faces 300 that are facing and opposed, into mutual contact, for example in their upper zone.
Basically, the concavity of the casting path TRC exploits the self-weight of the lower die halves 3 to close or at least reduce the slits therebetween.
This measure is very important because it allows the closed chain formed by the lower die halves 3 to slide, dragging and tensioning its casting stretch 13, for example by means of one or more motors and/or one or more drive pulleys or drive rollers, in particular, for example, by means of the first die advancing wheel 15 alone, while the second wheel 17 can be, for example, idle and dragged by the chain of the die halves 3.
The tensioning of the casting stretch 13 on one side tends to widen the slits present between the end faces 300 of the die halves 3 - but as has already been explained, this drawback can be considerably reduced when it is not completely eliminated by the curved shape of the casting path TRC- but on the other hand it keeps the casting stretch 13 of the chain of die halves 3 well straight and considerably facilitates the control and movement thereof, avoiding for example the drawbacks of some known continuous casting machines in which the casting stretch 13 of the chain of die halves 3 was made to operate compressed, for example by means of a pair of drive wheels rotating at different speeds.
The compression of the casting stretch 13 tended to deform the chain of the die halves 13 in all the directions of the space, bending it horizontally and vertically and twisting it, making it very difficult if not impossible the control and driving thereof and causing frequent failures, machine downtime and generally requiring a more frequent maintenance, as well as considerably increasing the leakage of molten metal through the slits between the die halves 3.
As already stated, preferably the casting channel 7 is generally inclined downwards (Figures 1 , 2 , 7 , 10 ); for example, if it is rectilinear - that is, if the casting path TRC is a straight line - it is preferably inclined by an angle θ [theta] approximately equal to 1-10 sexagesimal degrees or 5-7 sexagesimal degrees with respect to the horizontal, so as to favour the outflow of the molten metal.
If the casting channel 7 - and correspondingly the casting path TRC- has a concave shape, as has already been said, the relative tangent straight line TGT is preferably inclined with respect to the horizontal, for example, by about 1-10 sexagesimal degrees or by 5-7 sexagesimal degrees.
In order to maintain the casting stretch 13 of the chain of the die halves 3 in a suitable tension, the continuous casting apparatus 10 is advantageously arranged to move or adjust, through a suitable actuator, the position of the rotation axis of the first 15 and/or of the second die advancing wheel 17, making it perform for example one or more of the following movements:

a displacement which moves the rotation axes of the first wheel 15 and of the second wheel 17 away from or toward each other;
a movement having a non-zero horizontal component of the rotation axis of the first 15 and/or of the second wheel 17.

Again in order to control the tension of the casting stretch 13 of the chain of die halves 3, the continuous casting apparatus 10 may optionally be provided with a system for controlling the rotation speed of the drive wheel(s) which drag(s) the chain of the die halves 3, for example for controlling the rotation speed of the first 15 and/or of the second advancing wheel 17 so as to keep the chain always under tension and not under compression.
Advantageously, the apparatus 10 comprises a zone for washing the lower die halves 3, which is preferably located at at least part of the return stretch 32, and third nozzles 45 are arranged to strike the lower die halves 3 with a jet of water or other high-pressure liquid so that they are washed from metal residue and/or other incrustations or dirt (Figure 8 ).
Advantageously, the third nozzles 45 are directed toward the side of the lower die halves 3 on which the respective casting channel stretch 7 is obtained by effectively cleaning it from the remains of molten metal and other dirt, in general the removal of which could be more difficult with only the nozzles 43 of the casting stretch 13, where the casting channel 7 is closed at the top by the die-closing belt 9.
Advantageously, the apparatus 10 also comprises a system for supplying lubricating and/or detaching oil 50, at the direction change supports and/or the rotary elements.
Preferably, the so-called return stretch 32 and the washing zone - are enclosed by one or more casings 102, 104 - preferably for example metal - preferably provided with doors which allow access to the chain of the die halves 3 for example for inspection or maintenance and at the same time retain inside the apparatus 10 and allow to recover more easily the dirty water or other exhausted washing liquid which drips from the machine, avoid soiling the surrounding environment (Figure 1 ).
Advantageously, the apparatus 10 further comprises a cutting station 106 arranged to cut the cast bar solidified into segments at the desired length (Figures 2 , 14 ).
This cutting station 106 is arranged, for example, downstream of the casting channel 7.
This cutting station 106 can be arranged to cut the bar of solidified metal into ingots or other segments by blanking or fracture, substantially without chip removal, and for example can be a shearing machine (Figure 2 , 14 ).
In this case the shearing machine 106 is advantageously provided with a pair of shearing rotors 1060, 1062 placed substantially side by side, arranged to rotate about themselves about rotation axes ARC1, ARC2 that are parallel or in any case longitudinal the one to the other (Figure 14 ).
The shearing rotors 1060, 1062 are moreover suitably spaced apart so as to allow the metal bar to be cut BRR to pass between them (Figure 14 ).
For this purpose one of the two rotors 1060 can be arranged substantially above the other 1062 (Figure 14 ).
Each shearing rotor 1060, 1062 is preferably provided with one or more blades or cutting edges 1064, more preferably with a pair of cutting edges 1064 arranged in diametrically opposite positions the one with respect to the other that is, angularly offset by about 180° the one from the other (Figure 14 ).
Advantageously, the shear 106 is arranged to allow the adjustment of the radial position of the blades 1064, i.e. to vary the radial distances of the respective cutting edges from the rotation axes of the respective shearing rotors 1060, 1062, that is, to make them project radially more or less with respect to the rest of the respective shearing rotors 1060, 1062.
Advantageously, the shear 106 is arranged to rotate the two shearing rotors 1060, 1062 at speeds which may be different from each other by varying each rotation speed, possibly independently of the other.
For this purpose, the shear 106 is advantageously provided with two actuating motors 1066, 1068, for example electric motors with variable speed, each of which is arranged to actuate a respective shearing rotor 1060, 1062.
Advantageously, the rotation speed of the two motors 1066, 1068 can be varied and controlled independently of that of the other motor 1068, 1066.
Advantageously, the shear 106 is arranged to vary the angle of attack of the cutting edges 1064 and their offset, for example based on the type of metal alloy to be cut.
In other words, the rotation speeds of the two shearing rotors 1060, 1062 and the radial distances of the respective cutting edges from their rotation axes may be different from each other and chosen in such a way as to ensure that, at the end of their metal incision stroke, the two cutting edges meet or in any case are at or near the shear center.
The shear center according to structural engineering and the theory of elasticity in solids is defined as the point of a cross-section of the bar or ingot through which the straight line of action of the shearing stress must pass so that substantially no twisting moment is produced on the section.
More generally, the rotation speeds of the two shearing rotors 1060, 1062 and the radial distances of the respective cutting edges from their rotation axes can be different from each other and chosen in such a way as to ensure that, at the end of their metal cutting stroke, i.e. when two cutting edges are at the minimum distance from each other, each cutting edge is at a distance equal to or lower than 25 millimetres from the shear center, more preferably at a distance from the shear center equal to or lower than 20 millimetres, 15 millimetres, 10 millimetres or 5 millimetres, two millimetres, one millimetre, 0.86 millimetres or 0.5 millimetres.
In this way the cutting quality by shearing or blanking increases considerably with respect to that obtained with known shearing machines, in which at the end of the cutting strokes the cutting edges meet or touch at or near half the height of the cross sections of the bar or ingot to be cut.
The ingots cut with the known shearing machines have ends with very rough and irregular, chipped surfaces; moreover, during cutting the blades make the ingot raise, with the risk of causing damage to people and things around.
Again for this purpose, the apparatus 10 is advantageously provided with or connectable to a logic unit (not shown) arranged to store, for example through a database, the various angles of attack and offset of the cutting edges 1062 that are the most suitable for cutting each metal alloy cast by the apparatus 10.
The logic unit can then automatically set the shearing machine 106 based on the type, or the composition or recipe, of metal alloy chosen for the next casting to be made.
The use of a shearing unit rather than a sawing machine or other cutting unit with chip removal allows to eliminate the considerable waste of recast metal which would form the cutting chips.
In an embodiment not shown, the blades or cutting edges 1064 instead of on shearing rotors 1060, 1062 which rotate on themselves can be fixed to or in any case actuated by respective translating jaws which grip the metal bar until it is cut off.
The crucible 28, 28' may comprise a collection tank 280 and a channel 282, 282' arranged to pour the molten metal coming from the collection tank 280 into the casting die 1 - preferably in the more upstream part of the casting stretch 13- (Figures 16 , 17 , 18 ).
The collection tank 280 can be, for example, open at the top (Figures 16 , 17 , 18 ).
The channel 282, 282' preferably has a tubular shape, with preferably rectangular cross (Figures 16 , 17 , 18 ), square or possibly, for example, also polygonal, circular, oval or elliptical sections.
In any case the channel 282, 282' ends downstream with an outlet mouth 284, 284' which is advantageously inclined with respect to the longitudinal axis of the channel 282, 282'.
During normal operation of the apparatus for producing metal bars through continuous casting 10, the channel 282, 282' extends generally horizontally or moderately inclined with respect to the horizontal, so that for example its longitudinal axis has an inclination ϕ [phi] with respect to the horizontal ORZ equal to or lower than 45°, or 30°, or 15° or 5°.
Preferably, during normal operation, the axis of the channel 282, 282' and the axis of the casting channel stretch 7 into which the channel 282, 282' introduces the molten metal are substantially parallel or longitudinal to each other.
Advantageously during normal operation the outlet mouth 284, 284' is substantially inclined with respect to the longitudinal axis of the channel 282, 282', for example substantially inclined with respect to the stretch that is more downstream of the longitudinal axis of the channel 282, 282' (Figure 18 , 19, 20) and is not instead substantially perpendicular with respect to said longitudinal axis.
In other words, the outlet mouth 284, 284' is substantially inclined in the form of a drip cone (Figures 16 , 17 , 18 ).
During normal operation, the outlet mouth 284, 284' can be substantially turned toward the bottom of the casting channel (Figure 16 , 17 ) or turned in a direction away from the bottom of the casting channel (Figure 18 ), with an inclination ψ [psi] with respect to the axis of the channel 282, 282' in absolute value for example ranging between 5-80°, or between 10-70°, between 30-50°, between 40-50°.
The longitudinal axis of the channel 282, 282' can be, for example, substantially rectilinear (Figures 16 , 17 , 18 ).
During operation at least one stretch of the channel 282, 282' is at least partially inserted in the casting channel (Figures 16 , 17 , 18 ).
For this purpose, some outer walls of the channel 282, 282' can mate with some inner walls of the casting channel 7 and have shapes that are for example, complementary to each other, that is, some inner walls of the casting channel 7 can be substantially a negative copy of some outer walls of the channel 282, 282' .
Due to the not negligible thickness of the walls of the channel 282, 282', the molten metal outflowing therefrom rapidly expands due to the sudden variation of the passage sections of the conduit in which it flows.
The drip cone shape of the outlet mouth 284, 284' makes this expansion less fast, thus also reducing turbulence in the molten metal which might cause slag in the casting and loss of level.
The outlet mouth 284, 284' turned in a direction away from the bottom of the casting channel (Figure 18 ) is particularly effective in reducing turbulence in the molten metal and making the variation of the passage sections gradual.
An example of possible operation and use of the continuous casting apparatus 10 is now described.
By rotating the first 15, the second die advancing wheel 17 and the wheel, pulley or roller 25 or other direction change support 25, the chain of the lower die halves 3 and the die-closing belt 9 are made to advance preferably so that in the casting stretch 13 they have the same speed with respect for example to the load-bearing frame 27, 27' and therefore slide substantially at the same speed the one with respect to the other.
The molten metal, preferably aluminium or the alloys thereof or other non-ferrous metal - is cast from the crucible 28, 28' - or in any case at the casting zone 11- into the casting die 1, while the movement of the rotatory elements 15 and 17 is active.
The metal casting can enter the casting die 1 at the zone in which the roller conveyor 23 or other first direction change support 23 firmly presses the die-closing belt 9 against the chain of lower die halves 3, closing the casting channel 7 at the top.
In a first part that is more upstream of the rectilinear casting stretch 13 the metal is cooled by the first nozzles 41, which cool for example with air jets each lower die half 3 from the three lower, right and left, sides with reference to the direction of advancement of the casting, and by the second nozzles 43 which cool, for example, with jets of water or other cooling liquid - preferably directed from the top downwards - the die-closing belt 9.
Preliminary cooling by air or other cooling gas offers the following advantages:

a smaller quantity of water is used - at least 5% less
by exploiting the thermal inertia of the lower die halves 3;
a softer cooling is obtained, avoiding the immediate return of the liquid metal inside the very first stretch of the casting channel, which causes potential problems in the solidification step.
problems of surface quality are avoided if particularly fluid alloys are cast which inevitably have micro-leakages in the initial zone of the casting channel;
in general, the thermal shock of the materials of the various components is reduced.

In a second part of the optionally rectilinear casting zone 13 the metal material is cooled by jets of water from all sides.
Once the casting zone, possibly but not necessarily rectilinear, has been completed, the metal bar now solidified continues its rectilinear advancement, progressively exiting from the casting die, thanks to the change of direction of the chain of lower die halves 3, which deviates from the rectilinear path resting and winding around the wheel, roller or pulley 15, and also thanks to the change of direction of the die-closing belt 9 which also deviates from the rectilinear path resting and winding around the wheel, roller or pulley 25.
The bar of solidified metal can then be transported to a cutting station 106, where it will be cut in such a way as to divide it into a plurality of ingots or in any case segments of the desired length.
During their path, in addition to cooling, the die halves 3 are advantageously washed by the first 41, by the second 43 and by the third nozzles 45.
In particular, the third nozzles 45 contribute considerably to washing also the inside of the casting channel 7, since they are either facing or in any case turned toward it; for example, in the return stretch 32 if the die halves 3 advance with the stretches of the casting channel turned downwards, the third nozzles 45 are preferably turned upwards.
From the previous description it is clear that the continuous casting apparatus 10 described above allows to close better, in particular with a better tightness against leakage of liquid metal, the casting channel 7 by means of the die-closing belt 9 at or near the casting zone 11, thus stressing and damaging less the die-closing belt 9, imposing it greater radii of curvature at the first 23 and at the possible second direction change support 25.
The decoupling between the adjustment movements of the first 23 and of the second direction change support 25 as well as the pressers 35 and of the relative fastenings 38, 100 to the load-bearing frame 27, 27' further contributes to reducing the mechanical and fatigue stresses in the die-closing belt 9 and to extending the operating life thereof, and further contributes to improving the tightness against molten metal leakage over the entire length of the casting channel.
Thanks to the cooling system by air or other gas, the apparatus 10 also allows to bring the lower die halves 3 back to a lower temperature - when appropriate - in the casting zone 11, at the same time reducing the contaminations of the molten metal caused by the cooling water and cooling the molten metal in a softer and more gradual manner in the casting zone 11.
In its return stretch 32 the chain of lower die halves 3 can be firmly supported by guides on which the advancement projections 6 slide.
Again in its return stretch 32 the chain of lower die halves 3 can be effectively washed by means of further nozzles not shown.
The embodiments previously described are subject to different modifications and variations without departing from the scope of protection of the present invention.
For example, in a further aspect thereof, the present invention relates to an apparatus (10) for producing metal bars through continuous casting, comprising a continuous casting die (1) in turn comprising a casting zone (11) arranged to receive molten metal, a plurality of lower die halves (3) arranged in succession the one after the other and an upper closure system (5), and wherein:

each lower die half (3) forms the bottom (70) and the flanks (71) of a casting channel stretch (7), is open on the flank opposite to the side of the bottom (70) of the respective casting channel stretch (7) and at the ends adjacent to the die halves (3) immediately preceding and following the lower die half (3) considered;
the plurality of lower die halves (3) is arranged to advance along a path that downstream of the casting zone (11) forms a casting for example rectilinear stretch (13) in which the casting channel stretches (7) of at least part of the lower die halves (3) are aligned along a common casting, for example substantially rectilinear axis;
the path of the lower die halves (3) downstream of the casting for example rectilinear stretch (13), changes direction so as to detach the lower die halves (3) from a metal bar formed by the metal that has solidified in the casting for example rectilinear stretch (13);
the upper closure system (5) comprises:
- a die-closing belt (9) made of metal material and closed on itself which, at the casting for example rectilinear stretch (13), closes a part of the lower die halves (3) on the side opposite to their bottoms (70) of the stretches of the casting channel (7), which die-closing belt (9) at or near the casting zone (11) forms a first direction change stretch;
- a belt-pressing system (21) arranged to press the die-closing belt (9) against the open flanks of the lower die halves (3) at least in correspondence with at least part of the casting for example rectilinear stretch (13) and comprising at least a first direction change support (23) located at or near the casting zone (11) and arranged to rest against the die-closing belt (9) and to guide it along the first direction change stretch so that at the exit from the latter it advances in a direction different from that in which it enters the first direction change stretch;

(10)

(27, 27')

(23)

(27, 27')

(23)

(9)

(3)

(11),

(25)

(27, 27')

(9)

(23),

(23)

In a further aspect thereof, the present invention relates to an apparatus (10) for producing metal bars through continuous casting, comprising a continuous casting die (1) in turn comprising a casting zone (11) arranged to receive molten metal, a plurality of lower die halves (3) arranged in succession the one after the other and an upper closure system (5), and wherein:

each lower die half (3) forms the bottom (70) and the flanks (71) of a casting channel stretch (7), is open on the flank opposite to the side of the bottom (70) of the respective casting channel stretch (7) and at the ends adjacent to the die halves (3) immediately preceding and following the lower die half (3) considered;
the plurality of lower die halves (3) is arranged to advance along a path that downstream of the casting zone (11) forms a casting for example rectilinear stretch (13) in which the casting channel stretches (7) of at least part of the lower die halves (3) are aligned along a common casting, for example substantially rectilinear axis;
the path of the lower die halves (3) downstream of the casting for example rectilinear stretch (13), changes direction so as to detach the lower die halves (3) from a metal bar formed by the metal that has solidified in the casting for example rectilinear stretch (13);
the upper closure system (5) comprises:
- a die-closing belt (9) made of metal material and closed on itself which, at the casting for example rectilinear stretch (13), closes a part of the lower die halves (3) on the side opposite to their bottoms (70) of the stretches of the casting channel (7), which die-closing belt (9) at or near the casting zone (11) forms a first direction change stretch;

(10)

(40)

(41)

(3)

(13),

(41)

14

15;

apparatus

10

(43)

claim

15.

each lower die half (3) forms the bottom (70) and the flanks (71) of a casting channel stretch (7), is open on the flank opposite to the side of the bottom (70) of the respective casting channel stretch (7) and at the ends adjacent to the die halves (3) immediately preceding and following the lower die half (3) considered;
the plurality of lower die halves (3) is arranged to advance along a path that downstream of the casting zone (11) forms a casting for example rectilinear stretch (13) in which the casting channel stretches (7) of at least part of the lower die halves (3) are aligned along a common casting, for example substantially rectilinear axis;
the path of the lower die halves (3) downstream of the casting for example rectilinear stretch (13), changes direction so as to detach the lower die halves (3) from a metal bar formed by the metal that has solidified in the casting for example rectilinear stretch (13);
the upper closure system (5) comprises a die-closing belt (9) made of metal material and closed on itself which, at the casting for example rectilinear stretch (13) , closes a part of the lower die halves (3) on the side opposite to their bottoms (70) of the stretches of the casting channel (7), which die-closing belt (9) at or near the casting zone (11) forms a first direction change stretch;
in the casting stretch (13) the casting path (TRC) is substantially concave with concavity turned downwards.

In a further aspect thereof, the present invention relates to an apparatus (10) for producing metal bars through continuous casting, comprising a continuous casting die (1) in turn comprising a casting zone (11) arranged to receive molten metal, a plurality of lower die halves (3) arranged in succession the one after the other and an upper closure system (5) and a crucible (28, 28'), and wherein:

each lower die half (3) forms the bottom (70) and the flanks (71) of a casting channel stretch (7), is open on the flank opposite to the side of the bottom (70) of the respective casting channel stretch (7) and at the ends adjacent to the die halves (3) immediately preceding and following the lower die half (3) considered;
the plurality of lower die halves (3) is arranged to advance along a path that downstream of the casting zone (11) forms a casting for example rectilinear stretch (13) in which the casting channel stretches (7) of at least part of the lower die halves (3) are aligned along a common casting, for example substantially rectilinear axis;
the upper closure system (5), at the casting for example rectilinear stretch (13), is arranged to close a part of the lower die halves (3) on the side opposite to their bottoms (70) of the stretches of the casting channel (7);
the crucible (28, 28') is arranged to cast molten metal into the casting channel (7) and comprises a channel (282, 282') arranged to be inserted at least partially in the casting channel (7) and to introduce the molten metal therein;
the channel (282, 282') ends with an outlet mouth (284, 284') which is advantageously inclined with respect to the longitudinal axis of the channel (282, 282') .

The concave path TRC of the lower die halves 3 in the casting stretch 13 may have a shape tolerance TLR the absolute and overall value thereof is, for example, equal to PRTMAX/2, or PTRMAX/4 to PRTMAX/8 or to PRTMAX/10; the band defined by this shape tolerance and within which the shape of the casting path TRC may vary is schematically indicated by the dashed band of Figure 13 .
In a further aspect thereof, the present invention relates to a cutting station (106) arranged for shearing or blanking metal bars and ingots, for example the bars and the ingots produced by the casting die (1), and comprising at least one pair of cutting blades (1064) arranged to cut the bar or ingot by pressing in substantially opposite or opposed directions, wherein the cutting station (106) is arranged to end the cutting strokes of the pair of cutting blades (1064) substantially at or near the shear center of the cross sections of the bar or ingot to be cut.
In a further aspect thereof, the present invention relates to a cutting station (106) arranged for shearing or blanking metal bars and ingots, for example the bars and ingots produced by the casting die (1), and comprising at least one pair of cutting blades (1064) arranged to cut the bar or ingot by pressing in substantially mutually opposite or opposed directions, and a pair of actuators (1066, 1068) each of which is arranged to actuate a respective cutting blade (1064), and each actuator (1066, 1068) can impose on its respective cutting blade (1064) cutting movements and trajectories that are substantially independent of those imposed by the other actuator (1068, 1066) on its cutting blade (1064).
These actuators (1066, 1068) may be rotary electric motors, each of which is arranged or in any case adapted to rotate the respective cutting blade (1064) with rotations that are substantially independent of the rotations imposed by the other motor, for example, rotations at a speed substantially different from that of the other motor and/or by suitably phase shifting the rotations of the two blades (1064), and/or by making sure that one comes into contact with the bar or ingot to be cut before the other.
In a variant embodiment not shown, the cutting blades (1064) can cut the bars or ingots by translating or roto-translating with respect to the bars and with respect to the ingots and not only by rotating.
Every reference in this description to "an embodiment", "an example of embodiment" means that a particular feature or structure described in relation to such embodiment is comprised in at least one embodiment of the invention and in particular in a particular variant of the invention as defined in a main claim.
The fact that such expressions appear in various steps of the description does not imply that they necessarily only refer to the same embodiment.
Furthermore, when a feature, element or structure is described in relation to a particular embodiment, it is observed that it falls within the skills of the average person skilled in the art to apply such feature, element or structure to other embodiments.
Numerical references that only differ in terms of different superscripts 21', 21", 21 ^III unless specified otherwise indicate different variants of an element with the same name.
Moreover, all details may be replaced with other technically equivalent elements.
For example, the materials used, and the dimensions, may be any according to the technical requirements.
It is to be understood that an expression of the type "A comprises B, C, D" or "A is formed by B, C, D" also comprises and describes the special case in which "A is comprised of B, C, D".
The expression "A comprises an element B" unless specified otherwise can be interpreted as "A comprises one or more elements B".
References to a "first, second, third, ... n-th entity" have the sole aim of distinguishing them from one another but the indication of the n-th entity does not necessarily imply the existence of the first, second ... (n-1)th entity.
The examples and lists of possible variations of this application are to be considered as non-exhaustive lists.

Claims

Apparatus (10) for producing metal bars through continuous casting, comprising a continuous casting die (1) in turn comprising a casting zone (11) arranged to receive molten metal, a plurality of lower die halves (3) arranged in succession the one after the other and an upper closure system (5), and wherein:
- each lower die half (3) forms the bottom (70) and the flanks (71) of a casting channel stretch (7), is open on the flank opposite to the bottom side (70) of the respective casting channel stretch (7) and at the ends adjacent to the die halves (3) immediately preceding and following the lower die half (3) considered;

- the plurality of lower die halves (3) is arranged to advance along a path that downstream of the casting zone (11) forms a casting stretch (13) in which the casting channel stretches (7) of at least part of the lower die halves (3) are aligned along a common casting axis (TRC);

- the path of the lower die halves (3) downstream of the casting stretch (13), changes direction so as to detach the lower die halves (3) from a metal bar formed by the metal that has solidified in the casting stretch (13);

- the upper closure system (5) comprises:
- a die-closing belt (9) made of metallic material and closed on itself which, at the casting stretch (13), closes a part of the lower die halves (3) on the side opposite to their bottoms (70) of the stretches of the casting channel (7), which die-closing belt (9) at or near the casting zone (11) forms a first direction change stretch;

- a belt-pressing system (21) arranged to press the die-closing belt (9) against the open flanks of the lower die halves (3) at least in correspondence with at least part of the casting stretch (13) and comprising at least a first direction change support (23) located at or near the casting zone (11) and arranged to rest against the die-closing belt (9) and to guide it along the first direction change stretch so that at the exit from the latter it advances in a direction different from that in which it enters the first direction change stretch, wherein the points of rest of the die-closing belt (9) against the first direction change support lie substantially along a resting surface having an average radius of curvature (RC1, RC2) equal to or greater than 0.5 metres and which is substantially tangent to the path followed by the die-closing belt (9) along the casting stretch (13).
Apparatus (10) according to claim 1, wherein the casting path (TRC) forms a substantially rectilinear casting axis.
Apparatus (10) according to claim 1 or 2, wherein the casting stretch (13) is substantially rectilinear.
Apparatus (10) according to one or more of the preceding claims, wherein the casting stretch (13) is arranged to contain and solidify the molten metal.
Apparatus (10) according to one or more of the preceding claims, wherein in the casting stretch (13) the casting path (TRC) is substantially concave having the concavity turned downwards.
Apparatus (10) according to at least claim 5, wherein in the casting stretch (13) the casting path (TRC) comprises an arc of circumference.
Apparatus (10) according to one or more of the preceding claims, wherein the lower die halves (3) are fixed one after the other so as to substantially form a chain closed on itself, the chain of the lower die halves (3) forms the casting stretch (13) and a return stretch (32), by travelling along said return stretch the lower die halves (3) move from the more downstream end of the casting stretch (13) to the casting zone (11), in at least part of the return stretch (32) the chain of the lower die halves (3) possibly follows a convex path the convexity of which is turned downwards.
Apparatus (10) according to claim 7, arranged to make the lower die halves (3) advance by tensioning the chain formed by them at least in the casting stretch (13) .
Apparatus (10) according to at least claim 7 or 8, comprising a first die advancing wheel (15) arranged at or near the downstream end of the casting stretch (13), and the apparatus (10) is arranged to tension the chain formed by the lower die halves (3) by dragging said chain through the first die advancing wheel (15).
Apparatus (10) according to one or more of the preceding claims, wherein the first direction change support (23) comprises a roller conveyor in turn comprising at least three direction change rolling bodies (108) arranged to rest against the die-closing belt (9) during normal operation of the continuous casting apparatus (10), wherein said rolling bodies (108) may be, for example, wheels, pulleys or rollers.
Apparatus according to at least claim 10, wherein the roller conveyor of the first direction change support (23) is provided with at least five, and possibly at least ten direction change rolling bodies (108), for each meter of length of the linear development of the stretch of the die-closing belt (9) which rests against the roller conveyor (23).
Apparatus (10) according to claim 10 or 11, wherein the roller conveyor of the first direction change support (23) is arranged to guide the die-closing belt (9) along a first roller conveyor stretch (TR1) of its path having a first average radius of roller conveyor curvature (RC1), and a second roller conveyor stretch (TR2) having a second average radius of roller conveyor curvature (RC2) substantially lower than the first radius of roller conveyor curvature (RC1).
Apparatus (10) according to one or more of the preceding claims, comprising a load-bearing frame (27, 27') arranged to rest on a floor, and wherein the first direction change support (23) is fixed to the load-bearing frame (27, 27') so as to be able to vary its position with respect to the latter by adjusting the pressure with which said first support (23) presses the die-closing belt (9) against the lower die halves (3) by closing the casting channel at the top at least at or near the casting zone (11), the second direction change support (25) is fixed to the load-bearing frame (27, 27') so as to be able to adjust the tension of the die-closing belt (9) and to vary its position with respect to the latter with movements that are substantially independent with respect to those of the first direction change support (23), and/or moving according to one or more degrees of freedom that are substantially independent of the one or more degrees of freedom according to which the first direction change support (23) moves.
Apparatus (10) according to one or more of the preceding claims, comprising a cooling system (40) comprising one or more first nozzles (41) each of which is arranged to strike with a jet of air or other cooling gas the die halves (3) at least at part of the casting stretch (13), so as to cool it.
Apparatus (10) according to at least claim 14, wherein the cooling system (40) comprises one or more second nozzles (43) each of which is arranged to strike with a jet of water or other cooling liquid the die halves (3) and/or the die-closing belt (9) at least at part of the casting stretch (13), so as to cool them.
Use of an apparatus (10) having the features according to one or more of the preceding claims, for producing bars of a non-ferrous metal, such as aluminium or alloys thereof, through continuous casting.
Process for producing metal bars through continuous casting, comprising the following operations:
- providing an apparatus (10) for producing metal bars through continuous casting having the features at least according to claim 14 or 15;

- by means of the one or more first nozzles (41), bringing or maintaining the temperature of one or more lower die halves (3) in an interval of about 10-40 degrees centigrade.