U.S. patent application number 14/901642 was filed with the patent office on 2016-05-26 for crystallizer for continuous casting and method for its production.
This patent application is currently assigned to DANIEL & C. OFFICINE MECCANICHE S.P.A.. The applicant listed for this patent is DANIEL & C. OFFICINE MECCANICHE S.P.A.. Invention is credited to Andrea DE LUCA.
Application Number | 20160144424 14/901642 |
Document ID | / |
Family ID | 49035891 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160144424 |
Kind Code |
A1 |
DE LUCA; Andrea |
May 26, 2016 |
CRYSTALLIZER FOR CONTINUOUS CASTING AND METHOD FOR ITS
PRODUCTION
Abstract
Crystallizer for continuous casting comprising a tubular body
having at least one wall which defines a through longitudinal
casting cavity and a plurality of longitudinal grooves made at
least on one part of the wall and open toward the outside thereof.
A covering binding is associated to the external surface of the
wall to close the longitudinal groves and thus obtain corresponding
cooling channels configured to make a cooling liquid flow inside
them.
Inventors: |
DE LUCA; Andrea;
(Remanzacco, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DANIEL & C. OFFICINE MECCANICHE S.P.A. |
Buttrio |
|
IT |
|
|
Assignee: |
DANIEL & C. OFFICINE MECCANICHE
S.P.A.
Buttrio
IT
|
Family ID: |
49035891 |
Appl. No.: |
14/901642 |
Filed: |
June 30, 2014 |
PCT Filed: |
June 30, 2014 |
PCT NO: |
PCT/IB2014/062721 |
371 Date: |
December 28, 2015 |
Current U.S.
Class: |
164/444 ;
156/184; 205/122 |
Current CPC
Class: |
B22D 11/041 20130101;
B22D 11/055 20130101; C25D 5/56 20130101; B22D 11/04 20130101; B22D
11/124 20130101; C25D 5/48 20130101; C25D 5/34 20130101; B22D
11/059 20130101 |
International
Class: |
B22D 11/124 20060101
B22D011/124; B22D 11/059 20060101 B22D011/059; C25D 5/56 20060101
C25D005/56; C25D 5/34 20060101 C25D005/34; C25D 5/48 20060101
C25D005/48; B22D 11/041 20060101 B22D011/041; B22D 11/055 20060101
B22D011/055 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2013 |
IT |
UD2013A000090 |
Claims
1. Crystallizer for continuous casting comprising a tubular body
(11, 211) having at least one wall (12, 212) which defines a
through longitudinal casting cavity (13, 213) and a plurality of
longitudinal grooves (14) made at least on one part of said at
least one wall (12, 212) and open toward the outside thereof,
characterized in that a covering binding (15), comprising one or
more layers of fiber material, is irremovably wound around said
external surface of said at least one wall (12, 212).
2. Crystallizer as in claim 1, characterized in that said covering
binding (15) comprises at least a band (16) made using at least one
fiber impregnated, or pre-impregnated, with polymer material.
3. Crystallizer as in claim 2, characterized in that said polymer
material, when polymerized around said wall (12, 212), determines
the solid and irremovable attachment of said covering binding (15)
with respect to said wall (12, 212).
4. Crystallizer as in any claim hereinbefore, characterized in that
said fiber material is wound in a direction mainly transverse to
the longitudinal development of the wall (12, 212).
5. Crystallizer as in any claim hereinbefore, characterized in that
said fiber is chosen from a group comprising carbon fibers, glass
fibers, aramid fibers or combinations thereof, and said polymer is
chosen from a group comprising polyamide, epoxy or polyester
resins.
6. Crystallizer as in any claim hereinbefore, characterized in that
said covering binding (15) is wound around and in direct contact
with said external surface of said at least one wall (12, 212) and
closes said longitudinal grooves (14) thus obtaining corresponding
cooling channels (17) configured to make a cooling liquid flow
inside them.
7. Crystallizer as in any claim from 1 to 5, wherein said
longitudinal grooves (14) are closed by a metal layer (18) made
using electrolytic deposition techniques that thus defines a
corresponding plurality of cooling channels (17) configured to make
a cooling liquid flow inside them, characterized in that said
covering binding (15) is wound around and in direct contact with
said metal layer (18) to make rigid the whole consisting of said at
least one wall (12) and said metal layer (18).
8. Crystallizer as in any claim from 1 to 5, characterized in that
said longitudinal grooves (14) are closed by a lamina (23) made of
fiber-reinforced polymer material to define a corresponding
plurality of cooling channels (17) configured to make a cooling
liquid flow inside them, said covering binding (15) being wound
around and in direct contact with said lamina (23) made of
fiber-reinforced polymer material in order to make rigid the whole
consisting of said at least one wall (12) and said lamina (23) made
of fiber-reinforced polymer material (18).
9. Crystallizer as in any claim from 1 to 5, wherein said
longitudinal grooves (14) are closed by at least a plate (219)
associated to the external surface of said at least one wall (212)
to define a corresponding plurality of cooling channels (17)
configured to make a cooling liquid flow inside them, characterized
in that said covering binding (15) is wound around and in direct
contact with said at least one plate (219) to reinforce and
increase the safety of the connection of the at least one plate
(219) with said at least one wall (212).
10. Crystallizer as in any claim hereinbefore, characterized in
that said covering binding (15) has a thickness substantially
constant along the longitudinal extension of said tubular body (11,
211).
11. Crystallizer as in any claim from 1 to 9, characterized in that
said covering binding (15) has a variable thickness along the
longitudinal extension of said tubular body (11, 211) to define
zones of variable resistance and rigidity.
12. Method to obtain a crystallizer (10, 110, 210) for continuous
casting, comprising a step of making a tubular body (11, 211)
having at least one wall (12, 212) which defines a through
longitudinal casting cavity (13, 213) and a plurality of
longitudinal grooves (14) made at least on one part of an external
surface of said at least one wall (12, 212) and open toward the
outside thereof, characterized in that it also comprises a step in
which a covering binding (15), comprising one or more layers of
fiber material, is irremovably wound around said external surface
of said at least one wall (12, 212).
13. Method as in claim 12, characterized in that said covering
binding (15) comprises a band (16) made using at least one fiber
impregnated, or pre-impregnated, with polymer material resistant to
high temperatures, said band (16) being first wound around said
external surface of said at least one wall (12, 212) and then the
polymerization of said polymer material being provided in order to
solidly attach said covering binding (15) with respect to said wall
(12, 212).
14. Method as in claim 13, characterized in that after said winding
of said covering binding (15), it comprises a curing step during
which said crystallizer (10, 110, 210) is heated to a temperature
comprised between 30.degree. C. and 120.degree. C. and kept at this
temperature for a period comprised between 20 and 200 minutes.
15. Method as in claim 14, characterized in that after said curing
step a post-curing step is provided during which said crystallizer
(10, 110, 210) is heated to a temperature comprised between
80.degree. C. and 200.degree. C. and kept at this temperature for a
period comprised between 1 hour and 20 hours.
16. Method as in any claim from 12 to 15, characterized in that
said covering binding (15) is applied using the filament winding
technique.
17. Method as in any claim from 12 to 16, characterized in that,
before the winding of said one or more layers of fiber material, it
provides to fill said longitudinal grooves (14) with disposable
material, to deposit a metal layer (18) on the external surface of
said at least one wall (12, 212) by means of electrolytic
deposition techniques, in order to close said longitudinal grooves
(14), and to subsequently remove said disposable material from said
longitudinal grooves (14) so as to define corresponding cooling
channels (17).
18. Method as in any claim from 12 to 16, characterized in that,
before the winding of said one or more layers of fiber material, it
provides to close said longitudinal grooves (14) with at least one
lamina (23) made of a fiber-reinforced polymer material to define a
plurality of cooling channels (17), and in that during said
winding, said fiber material is wound around and in direct contact
with said lamina (23) made of fiber-reinforced polymer
material.
19. Method as in any claim from 12 to 16, characterized in that,
before the winding of said one or more layers of fiber material, it
provides to close said longitudinal grooves (14) with at least a
plate (219) associated to the external surface of said at least one
wall (212) so as to define a corresponding plurality of cooling
channels (17).
20. Method as in any claim from 12 to 19, characterized in that
said fiber material is wound around said wall (12; 212) at a
winding angle comprised between 0.degree. and 10.degree.,
preferably between 0.degree. and 5.degree., with respect to the
perpendicular to the axis of longitudinal development of the
crystallizer (10).
21. Method as in any claim from 12 to 20, characterized in that
said covering binding (15) comprises a band made using at least a
fiber impregnated or pre-impregnated with glue or polymer resin,
said covering binding (15) having a volumetric ratio of fibers of
60%, and glue or polymer resin of 40%.
22. Method as in any claim from 12 to 21, characterized in that
during the winding of said fiber material, fibers making up said
covering binding (15) are wound at a controlled tension between 1N
and 50N.
Description
FIELD OF THE INVENTION
[0001] The present invention concerns a crystallizer for continuous
casting, usable in the iron and steel making industry to cast
billets, blooms or other similar products, of any type and cross
section. The invention also concerns the method for its
production.
BACKGROUND OF THE INVENTION
[0002] Different crystallizers for continuous casting are known,
suitable to cast billets, blooms or other iron and steel products,
each having a tubular body provided with a through longitudinal
cavity with a desired cross section, corresponding to the cross
section of the product to be cast, for example circular, elliptical
or polygonal, and in which the liquid casting metal is suitable to
pass. On the wall or walls which define the tubular body of the
crystallizer and which have a thickness of some tens of
millimeters, a plurality of channels are normally made
longitudinally, which are part of a closed cooling circuit in which
a cooling liquid, for example water, is made to circulate.
[0003] Some examples of crystallizers for continuous casting and
corresponding production methods are described in the Italian
applications for patents of industrial invention UD2012A000192 and
UD2013A000013 filed by the present Applicant, which are
incorporated here as reference.
[0004] Another example of a crystallizer for continuous casting is
described in the document EP-A-1.468.760 and comprises a first
tubular body, or internal tubular body, which defines a casting
channel for the liquid metal, and a second tubular body, or
external tubular body, which is associated externally to the first
tubular body.
[0005] In particular, the internal tubular body is provided, on its
external contact surface with the external tubular body, with
support ribs and connection ribs alternating with the support
ribs.
[0006] The support ribs and the connection ribs protrude toward the
outside and extend along the axial extension of the
crystallizer.
[0007] The function of the support ribs is to maintain the external
tubular body distanced from the internal one, while the connection
ribs are inserted in attachment seatings made on the internal
surface of the external tubular body, defining a fixed-joint
mechanical coupling, making the internal tubular body able to be
disassembled from the external tubular body.
[0008] Moreover, the connection ribs and the support ribs define,
between the internal tubular body and the external tubular body, a
plurality of hollow spaces in which a cooling fluid flows.
[0009] The fixed-joint mechanical coupling between the internal
tubular body and the external tubular body does not guarantee a
hydraulic seal of the cooling fluid in the hollow spaces, since the
support ribs have only a distancing function for the external
tubular body and are not able to guarantee the hydraulic seal
between adjacent hollow spaces.
[0010] This disadvantage is linked to the rigidity, and the
geometric and dimensional tolerances of each of the two tubular
bodies and to the fact that the latter are not intimately coupled
to each other.
[0011] In particular, document EP-A-1.468.760 provides that the
internal tubular body is made of metal material, for example
copper, while the external tubular body is made of a metal or
non-metal material, a composite for example, such as laminate
carbon.
[0012] Moreover, it is known that traditional crystallizers are
affected by a series of disadvantages due to the variation in the
internal conicity of the crystallizer, at least around the meniscus
zone. Indeed, mainly in this zone, there is a tendency to expand
toward the outside, due to the heat stresses deriving from the
contact temperature between the liquid steel and the wall of the
crystallizer. This causes a reduction in conicity between meniscus
and upper entrance section, and a greater conicity than the
specification conicity in the lower segment of the crystallizer,
always with respect to the meniscus zone. This causes a
deterioration in the quality of the cast product because of the
alteration in the functioning conditions and consequent poor heat
conduction between the skin of the steel and the cooled wall of the
crystallizer itself.
[0013] Consequently, the probability of leakages of liquid steel
from the skin, also called "breakout", is increased, following the
lack of heat conduction which causes the skin to stick to the walls
of the crystallizer, called "sticking".
[0014] One purpose of the present invention is to make a
crystallizer for continuous casting, with cooling channels
incorporated in the walls, which overall has an increased
structural rigidity without increasing the thickness of its walls,
in order to guarantee an increased casting efficiency and an
increased quality of the product exiting from the crystallizer.
[0015] Another purpose of the present invention is to make a
crystallizer for continuous casting, of the type indicated above,
that is simple in construction and at the same time has a reduced
cost compared to known crystallizers, even when the crystallizer
has large sizes, for example a diameter or width equal to or more
than 800 mm, reducing to a minimum the use of metal, for example
copper, needed to make the walls of its tubular body.
[0016] It is also a purpose of the present invention to make a
crystallizer for continuous casting that allows to obtain cast
metal products of high quality, keeping the specification conicity
substantially unvaried, when both hot and cold.
[0017] Another purpose of the present invention is to make a
crystallizer for continuous casting, of the type indicated above,
that can be easily used, without any contraindication, in
association with a mechanical agitator, also called stirrer.
[0018] Another purpose of the present invention is to make a
crystallizer for continuous casting, of the type indicated above,
that is reliable and can be used, without any contraindication and
with maximum efficiency, even with a radioactive rod used to detect
the level of liquid metal inside the crystallizer during
casting.
[0019] Another purpose of the present invention is to perfect a
method to make a crystallizer for continuous casting, of the type
indicated above, that allows to reduce production costs without
reducing the characteristics of structural rigidity, safety,
reliability and thermal and thermo-mechanical efficiency of the
crystallizer itself.
[0020] Another purpose of the present invention is to perfect a
method that allows to make a crystallizer for continuous casting,
of the type indicated above, easily and with simple work steps,
that can have any shape and cross section, for example circular,
elliptical or polygonal.
[0021] 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
[0022] 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.
[0023] In accordance with the above purposes, a crystallizer for
continuous casting, according to the present invention, comprises a
tubular body with at least a wall that defines a through
longitudinal casting cavity and a plurality of longitudinal grooves
made at least on a part of an external surface of the at least one
wall and open toward the outside thereof.
[0024] According to one characteristic of the present invention, a
covering binding, comprising one or more overlapping layers of
fiber material, is irremovably wound around the external surface of
the at least one wall, so as to create an indivisible whole between
the at least one wall with the longitudinal grooves and the
covering binding.
[0025] Here and hereafter in the description and in the claims, by
covering binding we mean a material comprising a plurality of
fibers adjacent to each other to define one or more bands that,
once in position, cover at least part of the external surface of
the wall.
[0026] The layers of fiber can be impregnated with a polymer
material, which, once the covering binding has been wound around
the external surface of the wall, is polymerized and determines the
solid and irremovable attachment of the covering binding to the
wall.
[0027] This allows to obtain a crystallizer for continuous casting
that maintains its specification conicity unchanged whether it is
hot or cold, thanks to the reinforcement structure that the
external covering binding achieves for the walls of the
crystallizer.
[0028] Indeed the covering binding, wound tightly around the
crystallizer in a direction mainly transverse to its longitudinal
direction, limits the deformations and movements of the walls,
maintaining the internal conicity, while allowing the longitudinal
dilation due to heat phenomena for example between 0 and 4 mm.
[0029] According to a first form of embodiment of the present
invention, the covering binding is in direct contact with the
external surface of the at least one wall and closes the
longitudinal grooves. Corresponding cooling channels are thus
obtained, configured to make a cooling liquid flow inside them, for
example water, suitable to cool the tubular body of the
crystallizer.
[0030] According to a second form of embodiment of the present
invention, as an alternative to the first, the covering binding is
in direct contact with a metal layer made with electrolytic
deposition techniques; the metal layer, in its turn, is in contact
with the external surface of the at least one wall and closes the
longitudinal grooves to form a corresponding plurality of cooling
channels.
[0031] Therefore, unlike the technical solution described in
EP-A-1.468.760, which provides to use electrolytic deposition as a
solution to oxidation phenomena, the present invention describes
the use of electrolytic deposition with the purpose of creating
sealed cooling channels on the external surface of the walls of the
crystallizer.
[0032] In this way, the covering binding makes rigid the whole made
by the at least one wall of the crystallizer and the metal layer
associated thereto.
[0033] According to a third form of embodiment of the present
invention, alternative to the first two, it is provided that the
longitudinal grooves are closed by at least a plate associated to
the external surface of the at least one wall so as to define a
corresponding plurality of cooling channels inside which a cooling
liquid flows.
[0034] In this case, the covering binding is in direct contact with
the at least one plate so as to reinforce and increase the security
of the connection between the at least one plate and the at least
one wall.
[0035] According to a fourth form of embodiment of the invention,
it is provided that the longitudinal grooves are closed by at least
a lamina made of a fiber-reinforced polymer material, fiberglass
for example, associated to the external surface of the at least one
wall to define a corresponding plurality of cooling channels inside
which a cooling liquid flows. The covering binding, in this case,
is located in direct contact with the lamina of fiber-reinforced
polymer material in order to make rigid the whole made by the at
least one wall and the lamina of fiber-reinforced polymer
material.
[0036] The covering binding can be wound around the wall defining
even variable thicknesses in a longitudinal direction in the most
stressed zones, for example the meniscus zone. The variation in
thickness in a longitudinal direction of the covering binding can
even be some millimeters. Merely by way of example the covering
binding, in the non-thickened zone, has a thickness comprised
between 1 mm and 8 mm.
[0037] The variable thickness of the fibers which surround the
crystallizer, after complete polymerization of the covering
binding, allows to work with machine tools on the external
containing surface so as to obtain seatings for housing packings or
break-pins.
[0038] The method to make a crystallizer for continuous casting,
according to the present invention, comprises a step in which a
tubular body is made, of metal for example, more specifically of
copper, with at least a wall that defines a through longitudinal
casting cavity and a plurality of longitudinal grooves made at
least on one part of the external surface of the at least one wall
and open toward the outside thereof.
[0039] According to another characteristic of the present
invention, the method according to the present invention also
comprises a step in which a covering binding, comprising one or
more layers of fiber material, is associated to the external
surface of the at least one wall.
[0040] In particular, the covering binding comprises a band made
using at least a fiber, impregnated or pre-impregnated with for
example a volumetric ratio of fibers of 60%, such as carbon, and
glue or polymer resin of 40%. The polymer material is the type
resistant to high temperatures, that is, equal to or more than
100.degree. C., such as a polymer for example chosen from the group
comprising polyamide, epoxy or polyester resins.
[0041] The fibers can be chosen from a group comprising carbon
fibers, glass fibers, aramid fibers or similar.
[0042] The covering binding in fiber, which becomes rigid when the
polymer solidifies by polymerizing, can be applied using any known
technique, including the filament winding technique.
[0043] The polymerization of the polymer can occur through heat
polymerization steps, that is, reticulation of the resin, called
curing.
[0044] During the curing step, the crystallizer is heated to a
temperature comprised between 30.degree. C. and 120.degree. C. and
kept at this temperature for a period comprised between 20 and 200
minutes. These conditions determine the reticulation of the polymer
resin and therefore a solidarization of the binding to the wall or
walls.
[0045] This allows to guarantee better characteristics of
resistance and heat consolidation depending on the type of resin
applied.
[0046] In possible forms of embodiment, after the curing step, a
post-curing step can be provided during which the crystallizer is
heated to a temperature comprised between 80.degree. C. and
200.degree. C. and kept at this temperature for a period comprised
between 1 hour and 20 hours.
[0047] In possible forms of embodiment, for the whole duration of
the curing and/or post-curing steps, the crystallizer is kept in
rotation around its own axis.
[0048] According to one possible implementation, the crystallizer,
after the curing and possibly post-curing steps, can be subjected
to a forced cooling.
[0049] The operation of winding the covering binding on the wall
can include the installation, on a suitable apparatus and by means
of a dedicated apparatus, of the wall in rotating mode around an
axis of rotation and subsequent winding of the covering binding
perpendicularly to the axis of longitudinal development, or with a
winding angle comprised between 0.degree. and 10.degree.,
preferably between 0.degree. and 5.degree., with respect to the
perpendicular to the axis of longitudinal development of the
crystallizer.
[0050] The winding operation can occur with a controlled tension of
the fibers, for example from 1N and 50N per fiber.
[0051] The solution of using the covering binding, in particular of
fiber, around the tubular body of the crystallizer, which is new
and original, allows to obtain at least the following advantages:
[0052] increasing the rigidity of the hollow tubular body of the
crystallizer; [0053] maintaining the internal conicity of the
crystallizer both when hot and when cold; [0054] maximizing the
efficiency of a possible radioactive rod associated to the
crystallizer, given that the covering binding is transparent to
radiations; [0055] containing the costs of production of
crystallizers of any shape, or with any cross section, for example
polygonal, circular, or elliptical, and even of considerable sizes,
for example with diameters, or widths, equal to or more than 800
mm; [0056] reducing to a minimum the thickness of the walls which
define the tubular body of the crystallizer and therefore minimum
use of metal, for example copper, of which they are made; [0057]
prolonging the life of the crystallizer; [0058] improving the
quality of the cast product; [0059] possibility of working with
machine tools on the solidified covering binding, for example to
define grooves for sealing rings or holes for the insertion of
break-pins.
[0060] According to possible solutions of the method according to
the present invention, before winding the one or more layers of
fiber material it provides to fill the longitudinal grooves with
disposable material, for example wax, to deposit a metal layer on
the external surface of the at least one wall by electrolytic
deposition techniques, in order to close the longitudinal grooves,
and to subsequently remove the disposable material from the
longitudinal grooves so as to define corresponding cooling
channels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] These and other characteristics of the present invention
will become apparent from the following description of some forms
of embodiment, given as a non-restrictive example with reference to
the attached drawings wherein:
[0062] FIG. 1 is a perspective and schematized view of a
crystallizer for continuous casting according to a first form of
embodiment of the present invention;
[0063] FIG. 2 is an enlarged detail of the crystallizer in FIG.
1;
[0064] FIG. 3 is a perspective and schematized view of a detail of
a crystallizer according to a second form of embodiment of the
present invention;
[0065] FIG. 4 is a schematized view of a detail of a crystallizer
according to a third form of embodiment of the present
invention;
[0066] FIGS. 5 and 6 are schematized views of possible variants of
the crystallizer according to the present invention.
[0067] 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 OF THE PRESENT
INVENTION
[0068] With reference to FIGS. 1 and 2, a crystallizer 10 for
continuous casting according to the present invention, in a first
form of embodiment, comprises a tubular body 11 with a wall 12, for
example made of copper or its alloys, which defines a through
longitudinal casting cavity 13. The thickness of the wall 12 is for
example comprised between 10 mm and 50 mm.
[0069] There is a plurality of longitudinal grooves 14 on at least
an external part of the wall 12. Each longitudinal groove 14 is
open toward the outside of the wall 12.
[0070] A covering binding 15, which in this case comprises one or
more layers of a band 16 of fiber, impregnated or pre-impregnated
with a polymer resistant to high temperatures (that is, equal to or
higher than 100.degree. C.), is in direct contact with the external
surface of the wall 12 and closes the longitudinal grooves 14 from
the outside. In this way corresponding channels 17 are made,
configured to make a cooling liquid, for example water, flow inside
them. In this specific case, it is provided that the band 16
defines a plurality of layers wound on the external surface of the
wall 12 of the crystallizer 10.
[0071] In a second form of embodiment, a crystallizer 110 (FIG. 3)
according to the present invention comprises, interposed between
the covering binding 15 and the wall 12, a metal layer 18 made with
electrolytic deposition techniques, for example as described in the
application for a patent of industrial invention UD2013A000013
cited above.
[0072] In this case, it is the metal layer 18 that hermetically
closes the longitudinal grooves 14 from the outside of the wall 12
and defines the plurality of cooling channels 17.
[0073] Therefore, in this second form of embodiment, the covering
binding 15 is in direct contact with the metal layer 18, in order
to make rigid the whole made up of the latter and the wall 12. This
allows to have a very contained thickness of the metal layer 18,
for example in the range of one or two millimeters. The covering
binding 15 in this case has a containing function of the metal
layer 18 and guarantees the seal of the latter even at high working
pressures of the cooling fluid circulating in the channels 17.
[0074] According to the form of embodiment in FIG. 6, the metal
layer 18 can be replaced by a lamina 23 made of a fiber-reinforced
polymer material which, closing the longitudinal grooves 14 from
the outside, defines the corresponding plurality of cooling
channels 17. The covering binding 15 is wound intimately in direct
contact with the lamina 23 to make rigid the whole constituted by
the wall 12 and the lamina 23.
[0075] According to a third form of embodiment, a crystallizer 210
(FIG. 4) according to the present invention comprises a tubular
body 211 provided with a plurality of walls 212 defining a
longitudinal casting cavity 213. The longitudinal grooves 14, open
toward the outside, are made on the external surface of the walls
212, by removing material. At least one plate 219, in this specific
case four plates 219, are associated to the external surface of the
tubular body 211, for example welded or glued, and are provided to
close the longitudinal grooves 14 made on the walls 212 of the
tubular body 211 from the outside and to define the cooling
channels 17.
[0076] The plates 219 can be associated to the external surface of
the tubular body 211, for example, by braze welding or structural
gluing, in the same way as described in the Italian application for
a patent of industrial invention UD2012A000193 in the name of the
Applicant.
[0077] In this case too, as in the first form of embodiment, the
covering binding 15 is in direct contact with the surface of the
plates 219 that is external during use, to reinforce them and
increase the secure seal of the braze welding.
[0078] Forms of embodiment of the present invention provide that
the covering binding 15 has a constant thickness along the
longitudinal extension of the tubular body 11, 211.
[0079] Other forms of embodiment, one of which is shown in FIG. 5,
provide that the covering binding 15 is provided with a thicker
portion 20 that has a greater thickness than the thickness along
the longitudinal extension of the tubular body 11 or 211. In this
way it is possible to generate zones of the crystallizer 10 with
variable resistance and rigidity along its longitudinal extension
that are determined, for example, depending on a variable
development of the pressure of the cooling fluid in the cooling
channels 17 or on different conditions of mechanical and/or heat
stress to which it can be subjected during normal use.
[0080] According to other forms of embodiment of the present
invention, shown for example in FIG. 6, mechanical workings, for
example to define circumferential seatings 21 for housing sealing
rings or holes 22 for the insertion of break-pins, can be made on
the covering binding 15.
[0081] The method for producing each of the crystallizers 10, 110,
210 for continuous casting described heretofore comprises a step in
which the tubular body 11, 211 is made, with the wall 12 or walls
212 that define the longitudinal cavity 13, 213 and the plurality
of longitudinal grooves 14, made for example by removing material,
such as milling, at least on one part of the wall 12 or walls 212,
and open toward the outside thereof.
[0082] The method also comprises a step in which a covering binding
15, as described heretofore, is associated to the external surface
of the wall 12 or walls 212.
[0083] In particular, the binding 15 comprises the band 16 made
with one or more overlapping layers, using at least a fiber
impregnated or pre-impregnated with a polymer resistant to high
temperatures, as indicated above, that is chosen for example from a
group comprising polyamide, epoxy or polyester resins.
[0084] It can be provided, for example, that the wall 12 or walls
212 is or are installed on a winding machine, for example by means
of clamps or specific equipment to allow the subsequent winding
operation of the fibers around it.
[0085] The fibers can be polymerized in different curing passes,
for example a curing at 30-120.degree. C. for 20-200 minutes,
followed by a post-curing at 80-200.degree. C. for 1-20 hours
depending on the resin applied.
[0086] For example the covering binding 15 can be applied using the
filament winding technique.
[0087] It is clear that modifications and/or additions of parts may
be made to each of the crystallizers 10, 110, 210 for continuous
casting as described heretofore, without departing from the field
and scope of the present invention.
[0088] It is also clear that, although the present invention has
been described with reference to some specific examples of
embodiments, a person of skill in the art shall certainly be able
to achieve many other equivalent forms of crystallizer for
continuous casting and/or other methods to make them, having the
characteristics as set forth in the claims and hence all coming
within the field of protection defined thereby.
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