EP3060365B1

EP3060365B1 - Crystallizer for continuous casting and method for its production

Info

Publication number: EP3060365B1
Application number: EP14793898.9A
Authority: EP
Inventors: Gianbruno LUVARA'; Alfredo Poloni
Original assignee: Danieli and C Officine Meccaniche SpA
Current assignee: Danieli and C Officine Meccaniche SpA
Priority date: 2013-10-23
Filing date: 2014-10-22
Publication date: 2019-06-05
Anticipated expiration: 2034-10-22
Also published as: ITUD20130137A1; WO2015059652A1; EP3060365A1

Description

FIELD OF THE INVENTION

The present invention concerns a crystallizer for continuous casting provided with a plurality of channels made in its walls and through which a cooling liquid is made to pass.
In particular, the crystallizer can be used in the iron and steel industry to cast billets or blooms of any type and section, preferably square or rectangular, but also polygonal in general, or round. However, applications of the crystallizer to cast thin, medium or thick slabs are not excluded.

BACKGROUND OF THE INVENTION

Crystallizers for casting billets or blooms are known, having a tubular body inside which a liquid metal is cooled. It is also known to provide that the tubular body is provided, in the thickness of its walls and for at least part of its longitudinal development, with a plurality of channels of a shape and size suitable for the passage of a cooling liquid. The channels can be interconnected to each other to define a closed cooling circuit.
The operations to make the cooling channels on the length of the tubular crystallizer are particularly complex and costly in terms of time and equipment used. They require complex holing and finishing operations to define passage channels which optimize the flow of the cooling liquid. These entail high costs and long production times of the crystallizer.
Crystallizers for billets, blooms or slabs are also known, comprising a first component, or internal component, with an oblong development, and a second component, or external component associated externally and in contact with the external surface of the first component.
The first component and the second component can both be tubular in shape and be inserted one inside the other to define the casting cavity, or they can both consist of plates disposed resting one against the other to define the section shape of a wall of the crystallizer.
The first component is provided, on its external perimeter surface, with a plurality of grooves open toward the outside and made along at least a part of its length.
The second component is associated with the first component by means of mechanical connection means, for example using bolts, pins, nuts, tie rods or similar, to maintain a close contact between the external surface of the first (internal) component and the internal surface of the second (external) component. The grooves are therefore closed externally by the internal wall of the second component, thus defining closed channels through which the cooling liquid is made to circulate during use.
An example of this solution is described in the document JP-A-S59-229261 , in which the first internal component consists of plates provided with a plurality of holes made through in their thickness, while the second external component, also consisting of plates, is provided on its contact surface with the first internal component with a plurality of connection elements, for example, welded screws or studs disposed in a mating position with the position of the through holes.
The first component and the second component are coupled to each other by inserting the connection elements in the through holes and clamping them for example with threaded nuts.
Other examples of crystallizers with multiple components and provided with cooling channels are described, by way of example, in documents JP-A-2000.107836 , GB-A-2.055.644 and DE-A-39.42.704 . However, these known solutions are also particularly complex and costly to make, because of the difficult mechanical working needed.
In some known solutions, the second external component can comprise a plurality of plates, each of which is associated with an external surface portion of the first internal component by means of said connection means.
In this solution, the operations to assemble the first and the second component are particularly complex and long. Indeed, to guarantee the correct hydraulic seal of the cooling channels in each surface zone containing the grooves, it is necessary to provide a large number of connection means and perimeter seals with O-rings to guarantee the seal of the cooling water by the grooves. This is necessary to take into account the different thermal dilations to which the first component is subjected with respect to the second component.
One purpose of the present invention is to make a crystallizer for continuous casting that guarantees that high-quality cast products are obtained, and also allows to cast products with high productivity and in total safety.
Another purpose is to make a crystallizer for continuous casting that has a highly efficient heat exchange and long working life.
Another purpose of the present invention is to perfect a method to make a crystallizer for continuous casting of the type indicated above that is simple and quick to make and allows to reduce the production costs of the crystallizer.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.
In accordance with the above purposes, a crystallizer for continuous casting comprises at least a wall provided with a first component, or internal component, having a surface in which a plurality of grooves is made, separated by protruding portions. The wall is also provided with a second component, or external component, coupled to the surface of the first component to close the grooves and to define cooling channels suitable to allow the passage of a cooling liquid.
According to one aspect of the present invention, between the second component and the first component, where there are the protruding portions, intermediate between the grooves, in correspondence to at least part of them, longitudinal welding beads or segments are made, without using any filler material, in order to reciprocally connect the first component and the second component and to define the cooling channels.
Here and hereafter in the description and the claims, the term welding, or also concentrated beam welding, means that the join zones between the first and second component are subjected, only in the join zone, to a high thermal energy such as to obtain a localized fusion of the materials between the first component and the second component, so as to obtain a reciprocal union thereof.
Furthermore, according to possible solutions, the welding is the concentrated electronic beam type.
The thermal energy needed for melting the material can be obtained, merely by way of example and not restrictive of the present invention, due to the Joule effect, by ultrasounds, laser beam, known as laser beam welding, by an electronic beam, or by other forms of thermal energy production.
In this way, it is possible to define an intimate and permanent coupling of the first component and the second component that guarantees an adequate mechanical resistance equally distributed over the entire coupling zone between the two components, which practically become a single structure.
Welding using longitudinal welding beads between the protruding portions of the first component and the coupling surface of the second component with the first component guarantees a water-tight seal of the cooling channels even in the case of high working pressures to which the cooling liquid is subjected during use.
As well as the longitudinal welding beads, other beads may also be provided, for example transverse or with other geometries, able to increase the heat exchange.
The intimate coupling by welding of the two components, internal and external of the crystallizer, avoids having to use and apply dedicated connection means, such as for example threaded connections which as well as increasing the number of components that make up the crystallizer, also increase its production times and its costs. However, it is not excluded that removable type connections can be used during the manufacture of the crystallizer.
According to another aspect of the present invention, the grooves extend longitudinally along a longitudinal axis and the longitudinal welding beads extend for a large part of the length of the second component, that is, for at least half the overall length of the second component.
The present invention also concerns the method for making a crystallizer for continuous casting as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of one form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

fig. 1 is a partly sectioned perspective view of a portion of wall of a crystallizer according to the present invention;
fig. 2 is a cross section view of a crystallizer according to the present invention, in accordance with a first form of embodiment;
fig. 3 is a cross section view of a crystallizer according to the present invention, in accordance with a second form of embodiment;
fig. 4 is a cross section view of a wall of a crystallizer according to the present invention;
fig. 5 is a view of a longitudinal section of a crystallizer for continuous casting according to the present invention;
fig. 6 is a perspective view of a possible form of embodiment of the present invention;
fig. 7 is a perspective view of another variant of embodiment of fig. 6.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF SOME FORMS OF EMBODIMENT

With reference to fig. 1, a portion of a wall 11 of a crystallizer 10 for continuous casting is shown, by way of example, which comprises a first component 12, internal during use, and a second component 13, external during use.
The first component 12 comprises a first surface 14, internal during use, which during the normal functioning of the crystallizer 10 is in contact with the metal material that is cast, and a second surface 15, opposite the first surface 14 and external during use.
A plurality of grooves 16 are made in the second surface 15 of the first component 12, and develop along a longitudinal axis Z.
The longitudinal axis Z, according to possible forms of embodiment, substantially coincides with the direction in which, during use, the metal material is cast.
The grooves 16 are open toward the outside along the longitudinal axis Z and are separated by protruding portions 17, each of which defines the lateral walls of two adjacent grooves 16 and, with their protruding zone, that is, the outermost one, the interface zone with the first component 12.
In the form of embodiment shown in figs. 1-4, the grooves 16 have a substantially rectangular section shape, possibly with rounded edges, although other section shapes are not excluded.
For example, one possible form of embodiment, not shown in the drawings, provides that the grooves 16 have a trapezoid section shape, that is, dovetailed. In this case, it may be advantageous to provide that the grooves 16 are disposed with the larger base of the trapezoid section facing toward the internal part of the crystallizer 10, and with the smaller base of the trapezoid section facing toward the second surface 15. In this way the heat exchange capacity toward the internal part of the crystallizer 10 is increased, given the greater heat exchange surface and the greater quantity of cooling liquid in circulation.
The second component 13, made in a single body, in turn comprises a third surface 18, located during use against the second surface 15 of the first component 12, and a fourth surface 19, facing toward the outside during use.
The second component 13 is coupled to the second surface 15 of the first component 12, to close the grooves 16 laterally and to define cooling channels 20 in which a cooling liquid is made to circulate, as will be described hereafter.
Merely by way of example, the cooling channels 20 are configured to resist pressure stresses exerted by the cooling liquid of about 20 bar.
In particular, the second component 13 is located resting against the protruding portions 17 of the first component 12.
According to some forms of embodiment of the present invention, the second component 13 is coupled with the first component 12 by welding techniques, without using filler materials, and which provide to make longitudinal welding beads, hereafter welding beads 21, between the second component 13 and the protruding portions 17 of the first component 12, so as to ensure the mechanical and hydraulic seal of the cooling channels 20.
According to possible forms of embodiment, it may be provided that the welding beads 21 have a penetration depth P of the welding in the protruding portions 17 that is comprised between 3mm and 10mm, preferably between 4mm and 7mm, even more preferably between 4.5mm and 6mm.
In some forms of embodiment the welding beads 21 extend along the longitudinal axis Z for at least a part of the overall length of the second component 13, that is, for at least half the length of the second component 13, for example for a length comprised between 60% and 100% of the overall length of the crystallizer 10.
A preferred form of embodiment of the present invention provides that the welding beads 21 extend continuously for the entire length of the crystallizer 10, that is, for the entire length of the second component 13.
Some forms of embodiment of the present invention can provide that, in correspondence with at least some of the protruding portions 17 of the first component 12, more than one welding bead 21 is made.
It is advantageous to provide for example that in correspondence with the protruding portions 17, present in proximity to the lateral edges of the first 12 or second component 13, or in correspondence to each protruding portion 17, two welding beads 21 are made. In this way it is possible to increase the efficacy of the mechanical and hydraulic seal between the first component 12 and second component 13.
In possible implementations of the present invention, the welding beads 21 have a width comprised between 2mm and 8mm, preferably between 2mm and 6mm, more preferably between 3mm and 5mm.
According to possible solutions, the welding beads 21 can have a width equal to or less than the width of each protruding portion 17.
According to the form of embodiment shown in fig. 2, the crystallizer 10 comprises a plurality of walls 11, in this case four walls 11, reciprocally connected.
In the form of embodiment shown in fig. 2, it can be provided that the first components 12 of each of the walls 11 are made in a single body with each other, to define a tubular body 22 with a substantially rectangular tubular section, in this case square, in which, during use, the metal to be cast passes.
Providing a tubular body 22 in a single body not only increases the mechanical resistance to deformations but also allows to obtain a continuous heat exchange over the whole cross section of the crystallizer 10. In fact, in this case, possible discontinuities are prevented, which alter the heat transfer capacity and which generate zones of differentiated cooling in the crystallizer. Such zones would be particularly harmful for the final quality of the metal product cast.
Beveled edges 24 are made on the external surface of the tubular body 22, which connect the adjacent first components 12 to each other.
Some forms of embodiment provide that the angle of the beveled edges 24 is comprised between 30° and 60°, preferably between 40° and 50°, in this case about 45°.
The internal perimeter surface of the tubular body 22 has perimeter edges that are suitably rounded to prevent, in said zones, any intensification of the cooling action on the metal cast.
In other forms of embodiment, the tubular body 22 has a polygonal section shape, chosen also depending on the type of metal product that the crystallizer 10 has to obtain. In this case too, the edges between adjacent walls 11 are suitably beveled.
According to the form of embodiment shown in fig. 2, on each side of the first component 12 the respective second components 13 are connected, in the way indicated above.
The second components 13, in the form of embodiment shown in fig. 2, each comprise a plate 23, substantially flat, with an overall length equal to or less than the longitudinal extension of the grooves 16, and a width L less than the width B of the wall 11. In the assembled condition of the plates 23, a reciprocal separation gap G is defined between them. In particular, the reciprocal separation gap G between the plates 23 is defined by the thickness of the adjacent plates 23 and the beveled edge 24.
In other words, each plate 23 is connected to the tubular body 22 so as to prevent any reciprocal contact with the other plates 23 adjacent to it, even when the crystallizer 10 dilates thermally.
The particular configuration of the beveled edge 24 and the plates 23 coupled with the tubular body 22 so as to prevent any solution of continuity, or reciprocal contact thereof, makes the crystallizer 10 more yielding in the zone of the edges.
In this way the edges can be compared to a hinge around which two adjacent walls 11 can mutually rotate following both thermal and mechanical stresses to which the crystallizer 10 is subjected during use.
In this way it is possible to discharge the central zone of the walls 11 of the crystallizer 10, where there are the cooling channels 20, preventing any possible creation of cracks on the internal surface of the crystallizer 10, which could propagate toward the cooling channels 20.
According to still other forms of embodiment, one of which is shown for example in fig. 3, it may be provided that the second components 13 of each of the walls 11 may also be made in a single body with each other, to define another tubular body 25 into which the tubular body 22 is inserted. The wall 11 therefore has a substantially tubular configuration, open at its two ends.
This solution allows to define a crystallizer 10 that is extremely compact and resistant to mechanical and thermal stresses.
According to another variant embodiment, it may be provided that the wall 11 described above constitutes a part of a crystallizer 10 of the type with plates, an example of which is shown in fig. 4. According to this form of embodiment, the first component 12 and the second component 13 both have a mainly flat development, except for possible shaped portions, for example to allow the insertion of a nozzle for the molten metal. In this case, therefore, the wall 11 in its entirety has a substantially flat shape.
The first component 12, as in figs. 1-4, can be made of copper or its alloys, such as a copper-silver alloy, or a copper-chrome-zirconium alloy or copper-nickel-beryllium.
Some forms of embodiment provide that the first surface 14 of the first component 12 can be covered with a covering layer with the function of increasing resistance to wear, and also to allow low-friction sliding of the molten metal. Merely by way of example, the covering layer is made of material comprising an alloy of chrome or nickel-chrome.
The second component 13 can be made of a copper-silver alloy or copper-chrome-zirconium or tin bronze or aluminum bronze.
Merely by way of example, not restrictive of the present invention, and with reference to the forms of embodiment in figs. 1-4, the first component 12 has a thickness comprised between 15mm and 25mm, while the second component 13 has a thickness comprised between 4mm and 10mm.
Merely by way of example, not restrictive of the present invention, in the case of rectangular grooves 16, they have a width comprised between 5mm and 12mm and a depth comprised between 10mm and 15mm.
The ends of the crystallizer 10 are in turn connected to support and oscillation means 26 of the crystallizer 10 as shown in fig. 5. Each of the support and oscillation means 26, connected to one of the ends of the tubular body 22, comprises a first flange 27 and a second flange 28, disposed one above the other and reciprocally connected to each other. Between the first 27 and the second flange 28 hydraulic seal means 29 are interposed, in this case an O-ring.
In the form of embodiment shown in fig. 5, the grooves 16 extend for a determinate length which is less than the whole longitudinal development of the second component 13.
The ends of each groove 16 are in turn connected to respective connection channels 30 made in the second flange 28. The connection channels 30 are in turn connected to the cooling circuit to determine the circulation of the cooling liquid.
The ends of the grooves 16 terminate at the upper part rounded toward the connection channels 30, to reduce the losses of load due to the flow of the cooling liquid.
The method to make the crystallizer 10 for continuous casting shown in figs. 1 and 2 provides a first step of making the first component 12, a second step of making the second component 13 and a third step in which the first component 12 and the second component 13 are coupled with each other.
With reference to fig. 2, the first step of making the first component 12, in this case the tubular body 22, provides that, starting from a tubular section bar, already shaped and with the desired shape and sizes, the grooves 16 are made on its external surface 15.
Some forms of embodiment provide that the grooves 16 are made by chip removal operations, for example using a multi-toothed miller to reduce execution times.
Making the grooves 16 is particularly easy and quick compared with making the cooling channels 20 directly in the thickness of the wall 11.
An operation is also provided to make the beveled edges 24, for example by operations to remove material.
Some forms of embodiment can provide that the tubular body 22 is curved with respect to its axis of development, with a radius of curvature substantially equal to that of the continuous casting line. The curving operation is obtained by plastic deformation with the aid of a mold and/or press.
The second step provides to make the second components 13 to be coupled with the first components 12.
With reference to the form of embodiment in fig. 2, it is provided that the second components 13, in the form of plates 23, are obtained by shearing to size a flat plate. In particular, a first pair of plates 23, which during use are disposed opposite each other, is sheared with a substantially rectangular plan shape, while the other pair of plates 23 is sheared so as to follow the curvature conferred on the tubular body 22 in the first step.
In the third step it is provided to couple the first component 12 and the second component 13 with each other.
In particular, during the third step it is provided to make the welding beads 21 in correspondence with the protruding portions 17 provided between adjacent pairs of grooves 16.
The welding beads 21 can be made using one of the welding techniques chosen from a group comprising laser welding, electronic beam welding, ultrasound welding, resistance welding, plasma welding, friction stir welding (FSW).
According to a possible form of embodiment, the welding can be the fiber laser type which allows to reach wavelengths less than or equal to 1µm, particularly efficacious for making welding beads 21 on copper materials or alloys thereof.
From trials carried out, Applicant has verified that it is possible to obtain welding beads 21 with a depth sufficient for the purpose, for example 5mm, already with rather limited powers, in the range of 6-10 kW, and hence relatively inexpensive, by suitably setting the speed of feed.
Possible forms of embodiment of the present invention can provide that the third step comprises a sub-step of pre-heating the second component 13, and possibly also the first component 12, before the welding is carried out. Preheating can be made up to a maximum temperature of about 400°C, preferably comprised between 150 and 250°C. It is obvious that the intensity of heating must be such that it does not modify the micro-crystalline structure of the materials and their mechanical properties.
During the welding step proper it is possible to use a protection gas to protect the welding bath, so that it does not come into contact with the oxygen and therefore oxidation is prevented. Alternatively, the welding can be carried out in a controlled atmosphere environment.
Once the reciprocal coupling has been obtained of the first component 12 and the second component 13, subsequent operations may be provided, for its final use.
It is clear that modifications and/or additions of parts may be made to the crystallizer 10 for continuous casting, and the method to make the crystallizer 10 as described heretofore, without departing from the field and scope of the present invention.
For example, with reference to figs. 6 and 7, the crystallizer 10 has a tubular conformation and is provided with a first end 32, or entrance end, and a second end 33, or exit end, opposite the first end 32, into/from which respectively the metal material cast is introduced and discharged.
The first end 32 can be provided with at least an attachment seating 34, configured to allow to connect the crystallizer 10 to the support and oscillation means 26.
In a first form of embodiment, the first component 12 and the second component 13 are both defined by the walls 11 of a respective tubular body, as shown in figs. 3 and 6. In another form of embodiment, only the first component 12 is defined by the walls 11 of a tubular body 22 and on its external surface the plates 23 are associated, which constitute the second component 13, for example as described with reference to figs. 2 and 7.
According to the solution shown in figs. 6 and 7, the crystallizer 10 comprises a covering layer 31 that is wound on the surface, external during use, of the crystallizer 10, and for at least part of its length.
The covering layer 31 exerts on the second component 13 an action of compression and of containing the dilations.
In particular, according to fig. 7 the covering layer 31 ensure the connection resistance of the plates 23 and the first component 12.
In the case shown in fig. 6, the covering layer 31 is wound for only a part of the length of the crystallizer 10, for example for a length comprised between 20% and 50% of its overall length starting from the entrance end 32.
According to a variant embodiment, the covering layer 31 is wound over the entire length of the crystallizer 10.
When the covering layer 31 is associated with the external surface of the crystallizer 10 in proximity to the first end 32, it confers on the crystallizer 10 a predefined mechanical resistance in proximity to the zone of the meniscus, that is, in correspondence with the zone where the free level of the molten metal is positioned.
According to the form of embodiment in figs. 6 and 7, the covering layer 31 is wound on the external surface of the crystallizer 10 in a more internal zone than that where there is the attachment seating 34, evaluated along the longitudinal extension of the crystallizer.
Merely by way of example of the present invention, the covering layer 31 starts at least 50mm from the end edge of the first end 32.
According to a possible form of embodiment, the covering layer 31 can comprise a plurality of filaments, tightly wound one adjacent to the other, overlapping and drowned in a polymeric covering material, for example a polymer resin.
Merely by way of example, the filaments can be made of a material chosen from at least carbon fibers, glass fibers, aramid fibers, Kevlar or similar or comparable fibers.
The polymer resin can be the type that is resistant to high temperatures, that is, equal to or more than 100°C, for example a polymer chosen from the group comprising polyamide, epoxy or polyester resins.
According to possible formulations of the present invention, the covering layer 31 can be obtained using filament winding techniques.
According to other forms of embodiment, the covering layer 31 can be obtained using fibers pre-impregnated with polymer resin which is then polymerized.
Merely by way of example, not restrictive of the present invention, the covering layer 31 can develop axially, that is, parallel to the longitudinal axis Z, for a height of at least 300mm or more, and has a thickness variable between 8mm and 20mm.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of crystallizer 10 for continuous casting and the method to make the crystallizer 10, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

Crystallizer for continuous casting comprising at least a wall (11) provided with a first component (12) having an external surface (15) in which a plurality of grooves (16) is made, separated by protruding portions (17), and a second component (13) coupled to said external surface (15) of the first component (12) to close said grooves (16) and to define cooling channels (20) suitable to allow the passage of a cooling liquid, characterized in that between said second component (13) and said protruding portions (17) of said first component (12), longitudinal welding beads (21) are made, without using any filler material, in order to reciprocally connect said first component (12) and said second component (13) and to define said cooling channels (20).
Crystallizer as in claim 1, characterized in that said welding is chosen from a group comprising laser beam welding, electronic beam welding, ultrasound welding, resistance welding, plasma welding, friction stir welding.
Crystallizer as in claim 1 or 2, characterized in that said grooves (16) extend longitudinally along a longitudinal axis (Z), and in that said longitudinal welding beads (21) extend for at least a part of the length of said second component (13).
Crystallizer as in claim 3, characterized in that said longitudinal welding beads (21) extend continuously for the entire length of said second component (13).
Crystallizer as in any claim hereinbefore, characterized in that said longitudinal welding beads (21) have a penetration depth (P) of the welding in said protruding portions (17) comprised between 3mm and 10mm, preferably between 4mm and 7mm, even more preferably between 4.5mm and 6mm.
Crystallizer as in any claim hereinbefore, characterized in that in correspondence to at least some of said protruding portions (17) of the first component (12), more than one longitudinal welding bead (21) is made.
Crystallizer as in any claim hereinbefore, characterized in that it comprises a plurality of reciprocally connected walls (11), and in that the first components (12) of each of said walls (11) are made in a single body with respect to each other so as to define a tubular body (22) in which during use the metal to be cast passes.
Crystallizer as in any claim hereinbefore, characterized in that it has a substantially tubular shape and in that it comprises a covering layer (31) that is wound to its surface, external during use, and for at least part of its length.
Crystallizer as in claim 8, characterized in that it is provided with a first end (32) and a second end (33), opposite the first end (32), and in that said covering layer (31) is associated in proximity with said first end (32).
Crystallizer as in claim 8 or 9, characterized in that it comprises a plurality of filaments tightly wound one adjacent to the other, overlapping and drowned in a polymeric covering material.
Method to make a crystallizer (10) for continuous casting comprising a first step of making a first component (12), during which, on one surface (15) thereof, a plurality of grooves (16) are made, separated by protruding portions (17), a second step of making a second component (13), and a third step of coupling the second component (13) to said surface (15) of the first component (12) in order to close said grooves (16), to define cooling channels (20) suitable to allow the passage of a cooling liquid, and to make at least a wall (11) of said crystallizer (10), characterized in that during said third step, between said second component (13) and said protruding portions (17) of said first component (12), longitudinal welding beads (21) are made, without using filler material, in order to reciprocally connect said first component (12) and said second component (13) and to define said cooling channels (20).
Method as in claim 11, characterized in that said longitudinal welding beads (21) are made using one of the welding techniques chosen from a group comprising laser welding and electronic beam welding, ultrasound welding, resistance welding, plasma welding, friction stir welding.
Method as in claim 11 or 12, characterized in that said third step comprises a sub-step of pre-heating the second component (13), and possibly also the first component (12), before the welding is carried out.
Method as in claim 11 to 13, characterized in that it provides to make said crystallizer (10) of a substantially tubular shape and to wind a covering layer (31) on the surface, external during use, of said crystallizer (10) and for at least part of its length.
Method as in claim 14, characterized in that said covering layer (31) is wound on the external surface of said crystallizer (10) in proximity to a first end (32).
Method as in claim 14 or 15, characterized in that during the winding of said covering layer (31) it is provided to wind a plurality of filaments one adjacent to the other, overlapping and drowned in a covering polymeric material.