WO2020152363A1

WO2020152363A1 - Mold for continuous casting

Info

Publication number: WO2020152363A1
Application number: PCT/EP2020/051838
Authority: WO
Inventors: Riccardo CONTE; Andrea LEGHISSA
Original assignee: Danieli & C. Officine Meccaniche S.P.A.
Priority date: 2019-01-24
Filing date: 2020-01-24
Publication date: 2020-07-30
Also published as: AT17199U1; DE202020100298U1; IT201900001035A1

Abstract

Mold for the continuous casting of metal products, which comprises plate means (11) and corresponding counter-plate means (15) associated with each other by connection elements (16). The plate (11) has a first wall (13) in contact with the metal product cast and a second wall (14) on the side associated with the counter- plate (15). The second wall (14) of the plate (11) has a plurality of grooves (18) and anchoring means (17a) of the connection elements (16). Turbulence accentuation means (29) are provided at least in correspondence of the bottom ends of at least one inclined grooves.

Description

“MOLD FOR CONTINUOUS CASTING”

FIELD OF THE INVENTION

The present invention concerns a mold for continuous casting.

In particular, the present invention applies to molds of the type with plates, or in a single body, used to cast metal products such as billets, blooms, slabs or other types.

BACKGROUND OF THE INVENTION

Molds for the continuous casting of metal products are known, configured to define a casting cavity into which the liquid metal is cast and progressively solidified, while advancing in the mold in order to obtain the solid metal product at the end.

In the following description we will refer to a straight mold, but the present invention is also applicable to curved molds or suchlike.

By way of example only, with reference to fig. 1, molds 10 are known defined by a plurality of plates 11, connected together, or obtained in a single body, to define the casting cavity 12 into which the liquid metal is cast.

In the following description, we will refer to plates 11, meaning on each occasion both the plates 11 as such, and also one or more plates or walls 11 of the mold 10 in a single body.

The plates 11 are provided with a first face, or wall 13, which defines the casting cavity 12, and a second face, or wall 14, opposite the first wall 13.

It is also known that the plates 11 have an inlet edge and an outlet edge of the casting. The inlet edge defines the beginning of the zone into which the liquid metal is cast into the mold 10, while the outlet edge defines the zone in which the cast product exits the mold 10.

In this type of mold, with the plates 11 there are also associated counter-plates 15 by means of connection elements 16, configured to keep them in close contact with each other.

The plate 11 and the counter-plate 15 are provided with a plurality of holes 17 in which said connection elements 16 are anchored.

The plurality of holes 17 is generally organized according to aligned rows, parallel to the direction of casting and distanced from each other. It is also known that a plurality of grooves 18 are made in the second wall 14 of the plate 11, which form part of the cooling system of the plate 11 itself. These grooves 18 have a mainly longitudinal development, in a direction substantially parallel to the casting direction.

The counter-plate 15 is also provided with one or more introduction apertures and one or more discharge apertures, in a position coordinated with the ends of the grooves 18.

When the plate 11 and the counter-plate 15 are associated with each other, the cooperation between the grooves 18 of the plate 11 and the apertures of the counter-plate defines channels 19 in which a cooling liquid flows.

The presence of the holes 17 in the plate 11 determines a non-homogeneous distribution of the grooves 18 with respect to the surface extension of the plates 11.

This determines that groups of grooves 18 are reciprocally distanced, for example, by a first pitch PI, while when a row of holes 17 is interposed between them they are distanced by a second pitch P2 greater than the first pitch PI .

As shown in the thermal profile of fig. la, located in relation to the second pitch P2, the difference between PI and P2 entails that the temperature of the first wall 13 of the plate 11, in correspondence with the second pitch P2, is higher than the temperature of the first wall 13 of the plate 11 in correspondence with the first pitch PI .

This determines a non-uniform cooling on the width of the mold 10.

This also creates problems in the cast product. In particular, it determines the onset of surface defects in the cast product, and a reduction in the useful life of the mold 10, with consequent demand for maintenance and/or replacement interventions.

In addition, the non-uniform cooling forces a reduction in the casting speed, with a consequent reduction in the productivity of the plant.

It is known in the state of the art that the introduction of the cooling liquid into the channels 19 occurs in relation to the zone in which the metal is cast.

In the following description, we will refer to this usual condition, even if the invention is also applicable to molds 10 in which the introduction of the cooling liquid occurs from below or from an intermediate position. When the cooling liquid is introduced into the channels 19, it is subjected to a high turbulence due to the deviation imposed on the flow in order to make it divert from the direction of introduction to the direction connected to the casting axis.

When the cooling liquid is discharged, as well as having a higher temperature, it is subjected only to the outflow action, and therefore does not perform an efficient cooling action in this zone.

What is more, it is also known that on the interface walls between the plate 11 and the counter-plate 15, and in the proximity of the perimeter edges of the latter, there is provided a seating for containing a sealing element, or gasket, which prevents leakages of the cooling liquid between plate 11 and the counter-plate 15.

A non-optimized cooling, in relation to the discharge zone of the cooling liquid, causes damage to the sealing element as above over time, with consequent drawbacks in the sealing and duration of the mold 10.

JP 2 971747 discloses a continuous casting mold in which some of the grooves for the circulation of the cooling liquid that are adjacent to screw holes are inclined with respect to the normal axis to the wall of the mold.

One purpose of the present invention is therefore to provide a mold 10 for continuous casting that allows to increase the duration thereof and therefore improve productivity.

ft is also a purpose of the present invention to provide a mold 10 that allows to increase the quality of the casting.

It is also a purpose of the present invention to provide a mold 10 for continuous casting that has a longer duration.

It is also a purpose of the invention to provide a mold 10 for continuous casting which prevents the onset of leakages of cooling liquid over time.

It is also a purpose to increase the yield and productivity of a mold 10.

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 claim. The dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a mold for the continuous casting of metal products, in accordance with the present invention, comprises at least a plate and a counter-plate tightly associated with each other by connection elements.

The connection elements are anchored on holes made on the plate and, in corresponding positions, on the counter-plate.

In order to improve the cooling effect in the zone where the holes are present, the invention provides to improve the functionality of the grooves where the cooling liquid circulates.

According to the present invention, at least one of the grooves made in the plate is inclined in the direction of the thickness of the plate.

This inclination is defined by the median axis of the groove, inclined with respect to the second wall of the plate by an angle of inclination comprised between 30°÷85°, preferably between 45°÷80° and even more preferably between 60°÷80°.

According to a first variant, all the grooves associated with the respective rows of holes are inclined and converging toward the axis of the hole.

According to another variant, the grooves inclined and converging toward the axis of the hole have a length, or depth, greater than the non-inclined grooves that are not directly associated with the rows of holes. This allows to increase the effectiveness of the cooling action in correspondence with, or in the proximity of, the zone of the plates affected by the holes where no grooves are present.

According to another variant, all the grooves present between two rows of holes are inclined so as to present, in relation to the first wall, substantially uniform terminal pitches.

According to another variant, the depth of all or some of the grooves can vary according to the particular needs.

It should be noted that providing inclined grooves increases the flow rate of the cooling liquid and the exchange surface of the liquid.

These measures allow to obtain the desired cooling along the mold.

The invention, according to one or more variants, consequently, allows to reduce the formation of cracks on the finished product, and to improve the mechanical characteristics in general, both of the mold and also of the cast product.

Furthermore, the invention allows to increase the useful life of the mold, reducing the demand for maintenance and/or replacement interventions.

Furthermore, the invention allows to increase the casting speed with a consequent increase in the productivity of the plant.

The invention also provides to improve the turbulence of the cooling liquid, in at least one of the inclined grooves in which the discharge of the liquid itself occurs.

According to another variant of the invention, it is provided to improve the turbulence of the cooling liquid at least in the inclined grooves progressively from introduction to discharge.

Another variant of the invention provides turbulence accentuation means on the plate, which are associated with at least the inclined grooves.

Another variant of the invention provides that the turbulence accentuation means are applied on the counter-plate, in relation to the specific grooves.

According to some embodiments, the turbulence accentuation means comprise connection septa which connect at least the bottom or terminal ends of at least two inclined grooves.

According to a variant, each channel is equipped with its own cooling liquid discharge chamber.

Each connection septum is functionally suitable to accentuate the turbulence of the cooling liquid, improving its efficiency.

In some embodiments of the present invention, a connection septum is conformed as a connection channel, of variable shapes and sizes, according to the desired turbulences.

In alternative embodiments, the connection septum is conformed as a connection chamber, of variable shapes and sizes, according to the desired turbulences.

In other embodiments, the connection septum has connection zones, protuberances or edges, which further accentuate the turbulence of the cooling liquid.

In other embodiments, turbulence accentuation means are provided along at least part of the longitudinal development of at least one groove.

In some embodiments of the present invention, the accentuation means comprise protuberances, edges, recesses, rounded parts and/or connections between two or more grooves, and are suitable to accentuate the turbulences, and therefore the efficiency of the cooling.

The invention also allows to reduce wear and damage to the sealing element, as well as improve the casting process as a whole and the duration of the mold.

This characteristic therefore allows to further increase the useful life span, the casting speed and the productivity of the mold.

ILLUSTRATION OF THE DRAWINGS

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

- fig. 1 is a schematic section view of a plate and a counter-plate of a mold of the state of the art, joined by connection elements;

- fig. la shows the distribution of the thermal profile on the surface of the plate in the proximity of the anchoring means of the mold of fig. 1 ;

- fig. 2 is a schematic section view of an embodiment of a plate and a counter plate of a mold of the present invention, joined by connection elements;

- fig. 2a shows the distribution of the thermal profile on the surface of the plate in the proximity of the anchoring means of the mold of fig. 2;

- fig. 3 is a front view of a plate of a mold for slabs, according to an embodiment of the present invention;

- fig. 4 is a section view of the plate of fig. 3, along line II;

- fig. 5 is a section view of the plate of fig. 3, along line III, on which a counter plate has been positioned;

- fig. 6 is an enlarged view of fig. 5;

- fig. 7 is a schematic section view of an embodiment of a plate in accordance with the present invention;

- fig. 8 is a section view of an embodiment of a mold in accordance with the present invention;

- fig. 9 schematically shows a detail of an embodiment of a plate in accordance with the present invention; - fig. 10 schematically shows a detail of an embodiment of a plate in accordance with the present invention;

- fig. 11 schematically shows a detail of an embodiment of a plate in accordance with the present invention;

- fig. 12 schematically shows a detail of an embodiment of a plate in accordance with the present invention;

- fig. 13 schematically shows a detail of an embodiment of a mold in accordance with the present invention;

- fig. 14 schematically shows a detail of an embodiment of a mold in accordance with the present invention.

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 embodiment can conveniently be incorporated into other embodiments without further clarifications.

DESCRIPTION OF EMBODIMENTS

We will now refer in detail to the various embodiments of the present invention, of which one or more examples are shown in the attached drawings. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, the characteristics shown or described insomuch as they are part of one embodiment can be adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such modifications and variants.

Fig. 2 shows an embodiment of a mold 10 for the continuous casting of metal products according to the present invention.

In this embodiment, the mold 10 comprises a plurality of plates 11, connected to each other, or made in a single body (for example fig. 8), to define a casting cavity 12 into which the liquid metal to be solidified is cast.

What will be described below, with regard to a single plate 11, is also applicable to all the plates 11 connected to each other, that is, the case in which the casting cavity 12 is in a single body.

Figs. 3, 4 and 5 show, by way of example, a possible embodiment of a plate 11 suitable to be coupled with other plates in order to define a mold 10 according to the present invention.

Fig. 8 shows, by way of example, a mold 10 with a casting cavity 12 in a single body.

The plate 11 is advantageously, but not exclusively, usually made of copper or other metal with the required thermal conduction capacities.

The plate 11 has a first wall 13 in contact with the casting and a second wall 14 on the opposite side.

In the case shown, the first wall 13 and the second wall 14 extend parallel to each other, so that the distance between the two walls 13, 14 defines a constant thickness of the plate 11.

On the plate 11, it is possible to define a longitudinal axis Z (fig. 3) in the longitudinal direction, which typically corresponds to the direction of flow of the casting.

It is therefore possible to define an inlet edge 20 and an outlet edge 21 of the casting, substantially orthogonal to the axis Z, which also define a direction of flow of the casting. This direction of flow of the casting is indicated with an arrow on the axis Z in fig. 3.

In the graphic representations of figs. 3, 4 and 5, the plate 11 is oriented in such a way that the inlet edges 20 and the outlet edges 21 correspond respectively to the upper and lower ends.

It is also possible to define an axis X in the transverse direction, which corresponds to the direction perpendicular to the axis Z, lying in the plane of the second wall 14.

Finally, it is possible to define an axis Y orthogonal to the second wall 14 of the plate 11 (fig. 5).

The mold 10 also comprises a counter-plate 15 (figs. 2, 5 and 8), which during use is attached in a stable manner, in contact with the second wall 14 of the plate 11, by means of known connection elements 16.

In the example, the connection elements 16 consist of screws.

The counter-plate 15 has a first wall 22 which, during use, is in contact with the second wall 14 of the plate 11, and also has a second wall 23 on the opposite side.

The plate 11 and the counter-plate 15 are provided with a plurality of anchoring means, which can comprise any mean whatsoever suitable to anchor the connection elements 16 in a stable manner.

If the connection elements 16 are screws, the anchoring means can be threaded holes 17, and in particular, advantageously, blind holes 17a on the plate 11 and through holes 17b on the counter-plate 15, coordinated with each other and suitable for engagement.

Hereafter, for the description of the drawings, for explanatory purposes we will refer to holes 17, but this must not be considered as a limiting factor.

In the embodiment shown in fig. 3, the plurality of holes 17 is disposed for example as rows of holes 17, substantially parallel to the casting axis (axis Z).

It is in the spirit of the invention that the holes 17 are positioned in the manner that, on each occasion, is most useful and advantageous both in terms of anchoring and also in terms of heat exchange.

On the first wall 22 of the counter-plate 15 there is, by way of example, a containing seating 24, which extends in the thickness of the counter-plate 15 and is suitable to contain a sealing element 25.

When the plate 11 and the counter-plate 15 are in contact with each other, the internal edge of the containing seating 24 of the counter-plate 15 defines a cooling area 26 on the plate 11 (fig. 5), inside which a plurality of grooves 18 are made.

As indicated for the simplicity of the description in the attached drawings, the grooves 18 are linear since the holes 17 are shown by way of example in rows.

It is in the spirit of the invention to provide holes 17 disposed in another manner, more suitable for the specific requirements.

In this case, the grooves 18 will follow paths on each occasion suitable to guarantee uniformity of cooling.

In the case shown by way of example in fig. 3, the grooves 18 and the groups of holes 17 have a predominantly linear development, in this specific case parallel to the casting direction (axis Z), and entirely contained in the cooling area 26.

On the counter-plate 15, in a position coordinated with the ends of the grooves 18, there are present introduction apertures 27 and discharge apertures 28 of the cooling liquid.

When the plate 11 and the counter-plate 15 are brought into contact with each other and tightened together, the cooperation between the first wall 22 of the counter-plate 15, the introduction apertures 27, the discharge apertures 28, and the grooves 18, creates channels 19 in which the cooling liquid is made to flow (fig. 5).

During use, the cooling liquid is introduced in a desired manner into the introduction apertures 27, it circulates in the channels 19, and exits from the discharge apertures 28.

According to the embodiment shown by way of example in fig. 2, the median axis of the grooves 18 is both orthogonal (Y2) and also inclined (Y3) with respect to the second wall 14 of the plate 11.

In particular, according to the invention, where, for example, a blind hole 17a is present, the grooves 18 are advantageously inclined in order to reduce the pitch between the terminal parts of one groove 18 and the other.

This configuration therefore allows to improve the cooling thermal profile on the first wall 13 of the plate 11 (fig. 2a), since it reduces the temperature in correspondence with the holes 17 with respect to the state of the art (fig. la).

This arrangement also allows to reduce the formation of cracks on the finished product and to improve its mechanical characteristics in general.

The inclination of the grooves 18 can also lead to an increase in their depth, and therefore of their cross section, allowing to further lower the temperature of the plate 11 in correspondence with the rows of holes 17, increasing the flow rate of the cooling liquid.

In some embodiments, the angle of inclination a of the median axis Y3 with respect to the second wall 13 of the plate 11 is comprised between 30°÷85°, preferably between 45°÷80° and even more preferably between 60°÷80°.

According to the present invention, at least one groove 18 adjacent to a row of holes 17 is an inclined groove 18b, with a median axis Y3 converging toward the inside of the plate 11, in relation to the axis Y1 of the hole 17.

In the example embodiments shown in figs. 2 and 8, all the grooves 18 closest to the rows of holes 17 are inclined grooves 18b, with median axis Y3 converging toward the axis Y1 of the hole 17.

In alternative embodiments, such as the one shown in fig. 7 for example, all the grooves 18 lying between one and the other row of holes 17 are inclined grooves 18b, with variable angles of inclination a, so as to have, in relation to the first wall, uniform pitches between their terminal ends.

In the embodiment shown in fig. 2, moreover, the depth of the grooves 18 is variable, and, for example, the grooves 18 closest to the rows of holes 17 are deeper.

By way of example, fig. 9 shows an embodiment in which the grooves 18, both straight 18a and also inclined 18b, have non-rectilinear longitudinal developments, for example, in order to better adhere in correspondence with the holes 17.

By way of example, fig. 8 shows an embodiment of a mold 10 for billets or blooms, according to the present invention.

The studies and research carried out by the Applicant indicate that in correspondence with the introduction aperture 27 of the cooling liquid (fig. 5), turbulences are generated in the flow of liquid, which improve the heat exchange.

On the contrary, in correspondence with the discharge aperture 28, the cooling liquid has a flow that is tendentially more laminar.

A laminar flow worsens the heat exchange in correspondence with the outlet edge 21 of the plate 11, which leads to the deterioration of the sealing element 25 normally present in this area. According to one aspect of the present invention, the presence of turbulence accentuation means 29 is provided in order to improve the heat exchange of the cooling liquid.

This turbulence increases the heat exchange action of the cooling liquid in the proximity of the outlet edge 21 of the casting from the mold 10, improving the efficiency of the cooling liquid.

In some embodiments, such as for example those shown in figs. 1, 10, 11, 12, the turbulence accentuation means 29 are configured as a connection septum 29a between the ends of at least two inclined grooves 18, which septum allows to increase the turbulence of the cooling liquid toward the outlet edge 21 in plate 11.

The connection septum 29a of the present invention can have variable shapes and sizes, being conformed, for example, as a connection channel, as shown in the embodiment of figs. 11 and 12, or as a connection chamber, as shown in the embodiments of figs. 10 and 14, or also in another manner.

It is in the spirit of the invention to provide that the connection septa 29a are all or in part applied to the plate 11, as for example shown in the embodiments in figs. 10, 11 and 12, or all or in part applied to the counter-plate 15, as shown for example in the embodiments in fig. 14, according to the particular needs.

For example, fig. 14 shows an embodiment in which the connection septum 29a is conformed as a connection chamber located on the terminal part of the discharge aperture 28 of the counter-plate 15.

In some embodiments, the connection septum 29a connects at least adjacent inclined grooves 18, as shown by way of example in figs. 10, 11, or grooves 18 not adjacent to each other, as shown by way of example in fig. 12.

We have also found that the cooperation between the connection septum 29a and at least one inclined groove 18b, as shown by way of example in the embodiment of fig. 11, further improves the heat exchange action.

According to the invention, the connection septum 29a can be orthogonal to the first wall 13 of the plate 11, or inclined, or it can also have extensions 29b at one or both of its ends, as shown by way of example in the embodiment of fig. 10.

According to a variant, the connection septum 29a has one or more intermediate extensions, or one or more constrictions.

According to another variant, into at least one or more inclined grooves 18b there can be inserted or provided turbulence accentuation means 29 conformed as protuberances 29b, as shown in the embodiment of fig. 13.

In some embodiments of the present invention, the accentuation means 29 can be conformed as protuberances, edges, rounded parts, protrusions or any other mean whatsoever suitable to accentuate the turbulences of the cooling liquid and improve its efficiency.

The accentuation means 29 according to the invention can be present along the entire longitudinal development of the groove 18, or along part of it, or suitably positioned in order to dissipate the heat of the plate.

It is clear that modifications and/or additions of parts may be made to the mold as described heretofore, without departing from the field and scope of the present invention.

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 mold, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

In the following claims, the sole purpose of the references in brackets is to facilitate reading and they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.

Claims

1. Mold for the continuous casting of metal products, comprising plate means (11) and corresponding counter-plate means (15) associated with each other by connection elements (16), wherein the plate (11) has a first wall (13) in contact with the metal product cast and a second wall (14) on the side associated with the counter-plate (15), wherein the second wall (14) of the plate (11) has a plurality of grooves (18) and anchoring means (17a) of the connection elements (16), said grooves (18) and said anchoring means (17) being inside a cooling area (26); characterized in that said grooves (18) comprise at least one inclined groove (18b), with respect to the orthogonal of the second wall (14) of the plate (11) and extending in the thickness of said plate (11), wherein turbulence accentuation means (29) are provided at least in correspondence of at least one of said inclined grooves (18b).

2. Mold as in claim 1, characterized in that said turbulence accentuation means (29) comprise a septum (29a) that connect each other the bottom ends of at least two inclined grooves (18b).

3. Mold as in claim 1 or 2, characterized in that into at least one or more inclined grooves (18b) is inserted or provided turbulence accentuation means (29) conformed as protuberances (29b).

4. Mold as in any claim hereinbefore, characterized in that said at least one inclined groove (18) cooperates with an associated row of anchoring means (17).

5. Mold as in any claim hereinbefore, characterized in that said at least one inclined groove (18b) is convergent toward the axis (Yl) of the corresponding anchoring mean (17) and has a length or depth greater than the non- inclined grooves (18a) which are not directly associated with rows of anchoring means (17).

6. Mold (10) as in any claim hereinbefore, characterized in that, with respect to the second wall (14) of the plate (11), said inclined groove (18) has an angle of inclination (a) comprised between 30°÷85°, preferably between 45°÷80° and even more preferably between 60°÷80°.

7. Mold (10) as in any claim hereinbefore, characterized in that the pair of grooves (18) between which at least one anchoring mean (17) is interposed, at least in relation to said anchoring element (17), is formed by inclined grooves (18b), with median axes (Y3) converging with respect to each other and in relation to the axis of the anchoring mean (Yl).

8. Mold (10) as in any claim hereinbefore, characterized in that the turbulence accentuation means (29) have extensions (29b) to the grooves (18).

9. Mold

(10) as in any claim 1 to 8, characterized in that the turbulence accentuation means (29) are present in the plate (11).

11. Mold (10) as in any claim 1 to 8, characterized in that the turbulence accentuation means (29) are present in the counter-plate (15).

12. Mold (10) as in any claim 1 to 8, characterized in that the turbulence accentuation means (29) are present part in the plate (11) and part in the counter plate (15).