MXPA06007369A - Die cavity of a casting die for continuously casting billets and blooms - Google Patents

Abstract

The invention relates to a die cavity of a casting die for continuously casting billets, blooms and blanks, steel being cast in a die cavity having a cross-section with a partially curved peripheral (42) line, and cavity walls cooled. The aim of the invention is to create optimum conditions for a regular heat exchange between a forming strand shell and the die cavity wall along the peripheral line (42) of the strand cross-section, and to avoid solidification defects in the strand shell. To this end, the degree of curvature 1/R is reduced at least on part of the curved peripheral line (42) of the corner regions from peripheral lines (42`, 42") of the same corner regions, that are successive in the casting direction, and at least over part of the length of the die, in the concave corner regions of the die cavity, in order to control the targeted closure of the gap between the strand shell and the cooled die cavity, or a targeted strand shell deformation.

Description

CAVITY OF CONFORMING A LINGOTERA FOR THE CONTINUOUS COLLAR OF BARREL BARS AND DISBASTS FIELD OF THE INVENTION The present invention relates to a shaping cavity of a continuous cast ingot mold according to the preamble of claim 1. BACKGROUND OF THE INVENTION Continuous casting oblong products are predominantly cast in tubular ingot molds with rectangular cross section, particularly with approximately square or circular cross section. The billets and slabs are then further processed by rolling or forging. For obtaining continuous casting products with good surface and structural quality, particularly billets and slabs, a uniform heat transfer along the peripheral line of the cross section of the bar, between the bar, is of paramount importance. in formation and the wall of the shaping cavity. Numerous proposals are known for configuring the geometry of the shaping cavity, particularly in the areas of the corners in the half-round of the shaping cavity, in such a way that there is no gap between the crust of the forming rod and the ingot mold wall. of REF .: 174056 air, which give rise to a new heating of the bar scale or to an irregular transmission of heat along the peripheral line of the cross section of the bar. The corners of the shaping cavity of tubular ingot molds are usually rounded in the shape of a half-round. The larger the half rods are made in the shaping cavity of the ingot mold, the more difficult it will be to achieve a uniform cooling between the bar scale in formation and the ingot mold walls, particularly along the periphery of the shaping cavity. The incipient solidification of the rod, immediately below the level of the liquid steel in the mold, progresses differently in the straight sections of the periphery of the forming cavity with respect to the half-round areas. The flow of heat in the straight or essentially straight sections is practically one-dimensional and corresponds to the law of heat penetration through a flat wall. On the contrary, the heat flow in the rounded angular zones is two-dimensional and corresponds to the law of heat penetration through a curved wall. The resulting bar scale is generally made in the angular areas initially thicker than on the flat surfaces and begins to contract temporarily before and to a greater extent. This means that after the about 2 seconds the bar scale is detached from the ingot mold wall in the angular areas and an air gap is formed, which drastically worsens the heat penetration. This worsening of the heat penetration not only delays the further growth of the crust, but may even give rise to a new fusion of already solidified inner layers of the bar crust.This tilting of the thermal flux - cooling and reheating - gives place to defects of the bar, such as surface cracks and internal longitudinal cracks in the edges or in areas close to the edges, as well as to defects in shape, such as rhombicity, bottlenecks, etc. The larger the half rods are dimensioned with respect to to the lateral length of the bar cross-section, particularly when the radii of the half-rods are 10% and more than the lateral length of the cross-section of the forming cavity, the more frequent and larger the defects described in FIG. This is a reason why the radii of the half-rods are usually limited, as a rule, to 5 to 8 mm, in spite of the fact that for the subsequent rolling, greater curvatures on the edges of the bar would be advantageous. From JP-A-53 011124 an ingot mold is known billets for continuous casting with rounded angular radii in the shape of a half-round. In such ingot molds, the bar can be cooled in an irregular manner and bars with a cross section with spear-shaped edges and corresponding edge defects, such as cracks, etc., can be produced. To avoid such defects of the bar, it is proposed in said document to configure a quadrangular mold cavity with 2 small and 2 large angular half rods. Thanks to these different angular radii of the half rods, the objective is to obtain the solidification of an irregularly thick bar crust. Immediately at the exit of the ingot mold it is intended to compensate a delayed solidification in the corners with large radii by means of a reinforced cooling of the edges in the zone of secondary cooling. These measures are intended to achieve a cross section of bar free of contractions. From JP-A-60 040647 is known a continuous cast ingot for a bar of pouches. In the casting of pouch bars, longitudinal cracks often occur in the transition from the central web to the two terminal webs. This transition zone forms a rounded section of convex shape in the ingot mold, on which the profile bar is slightly angled during cooling of the central core. To avoid this sagging or the formation of cracks is proposed in said document to configure this convex transition curve of the ingot mold with a progressively increasing curvature towards the central core. From JP-A-11 151555 a further ingot mold is known for the continuous casting of billets and slabs. In order also to avoid in this ingot mold a rhombic deformation of the cross section of the bar, and in order to further increase the casting speed, the ingot mold is provided in the four corners, provided with half rods, of parts for cooling the corners especially conformed On the casting side these cooling parts of the corners are circular recesses in the ingot mold wall, which decrease in the forward direction of the bar and are reduced, towards the outlet of the ingot mold, to the curvature of the average Reed of the corner. The degree of curvature of the circular recess increases in the forward direction of the bar towards the outlet of the ingot mold. This configuration aims to ensure an uninterrupted contact between the angular zone of the bar crust and the angular parts of the ingot mold. Brief description of the invention The purpose of the present invention is to provide a geometry of the shaping cavity for a continuous cast ingot mold that ensures optimal conditions for a uniform heat exchange between the bar scale in formation and the ingot mold wall along the peripheral line of the bar cross section and, therefore, a symmetrical temperature field in the crust of the bar. The cooling and the geometry of the shaping cavity must be optimized particularly along the periphery of the shaping cavity with curved wall sections and the transition of curved wall sections to substantially rectilinear wall sections. The aim is to achieve an improved uniform solidification profile of a bar scale in formation during its passage through the ingot mold, in order to avoid stresses in the crust of the bar, the formation of air slits between the bar crust and the ingot mold wall, bottlenecks, spear-shaped edges of the cross section of the bar and cracks in the bar scale, etc. Furthermore, such a shaping cavity must allow, with respect to the state of the art, higher casting speeds and cheaper manufacturing costs. According to the invention, these purposes are achieved by the sum of the characteristics of the device claim 1. By the method according to the invention and the geometry of the mold cavity according to the invention it is possible to create optimum conditions for a uniform heat exchange along the peripheral line of the bar cross-section between a bar crust in formation and the wall of the forming cavity. The uniform and optimized heat exchange ensures that the crust of forming bar in the ingot mold solidifies with a uniform crystalline structure, throughout the periphery, free of defects such as cracks, stress concentrations, spear-shaped edges, etc. It is also possible to define such conformation cavities by means of mathematical functions of curves and to manufacture them economically in numerical control machine tools. When the conicity of the forming cavity has been established for a certain quality of steel and a certain residence time of a bar in formation within the mold cavity, the uniform growth of the crust can be verified by means of casting tests. the uniform heat penetration prefixed along the peripheral line. In order to compensate any residual differences in the penetration of the pre-set heat between the forming bar scale and the wall of the forming cavity, according to an advantageous embodiment, walls of the forming cavity with a greater degree of curvature can be cooled. lower measurement and those with less degree of curvature to a greater extent.

In a conventional mold, they connect straight lines from the periphery of the forming cavity tangentially, at the so-called tangent point, with a circular line of the angular curvature. Such point transitions and circular curvatures should advantageously be replaced by arcuate lines with a shape of a curve function with one or two base parameters and with an exponent, for example superelipse or super circle. Furthermore, by means of a suitable selection of the base parameters and exponents of the mathematical function of the curve, the curvature of consecutive arcuate lines in the forward direction of the bar can be varied continuously or discontinuously. By decreasing or increasing the exponent, shapes of arched lines, and therefore the geometry of the cavity, can be adapted to the casting parameters given. If the contact between the bar scale in formation and the chilled mold wall is not interrupted, during the passage through the ingot mold, by the uncontrolled formation of air slits, the thermal flow will correspond to physical laws of thermal flow. This idealized state presupposes that also the geometry of the mold cavity is configured according to the physical laws of the thermal flow, on the one hand, and according to the shrinkage of the bar crust, on the other hand, and that the geometry of the forming cavity is constituted according to functions of defined curves mathematically. According to an exemplary embodiment, an optimally defined cavity geometry, defined mathematically, is obtained when the arcuate lines of the peripheral line of the shaping cavity are chosen in accordance with the curve function of a superelipse = 1 and if consecutive arched lines in the forward direction of the bar are varied in their curvature or in their degree of curvature by choosing the exponent n "and the base parameters A and B (semiaxes of the ellipse). The penetration of the predetermined heat, essentially uniform, along the peripheral line is additionally possible to slightly deform, plastic, the bar scale inside the ingot mold, that is to force it to adapt to the geometry of the cavity. With a further example of embodiment it is proposed to compose the peripheral line of four arched lines, each of which covers an angle of 90. Consecutive arcuate lines in the direction of advance of the bar are dimensioned in such a way that a convex bar crust results deformed from the casting side of the ingot mold, at least in a first partial section of the ingot mold and during its passage through the mold cavity. ingot, in such a way that at least in central sections between the angular zones the convexity of the bar crust decreases or, in other words, the arched lines in the central sections of the periphery of the bar are flattened, or the degree is reduced of curvature 1 / R. If, for example, in a cross section of cavity of conformation similar to a rectangle, preferably similar to a square, it is intended to constitute an angular zone, configured as a half-round, between four essentially flat side walls, according to an embodiment the degree of curvature of consecutive half-arches in the forward direction of the bar can be chosen according to the curve function | x | n + |? | n = | R | n and the exponent "n" can be varied between 2.01 and 10. If a section of cavity of conformation similar to a rectangle must consist essentially of four arched lines, each comprising 1/4 of the peripheral line, according to a further example of embodiment the function of curve n = 1 will be chosen. and the exponent "n" of consecutive peripheral lines in the direction of advancement of the bar will vary between 4 and 50. In the case of a cavity cross section of conformation similar to a square or similar to a circle, combined with a slight plastic deformation of the bar crust, according to the Convex technology described in EP-PS 0 498 296, the value of the exponent "n" of consecutive peripheral lines in the forward direction of the bar can be, according to with a further example of embodiment, for rectangular formats of 4 - 50 and for circular formats of 2 to 2.5. Apart from mathematically defined arcuate peripheral lines of the cross section of the ingot mold cavity, for the achievement of a predetermined, essentially uniform heat penetration, the dimensioning of the water cooling of the copper wall can also be taken into consideration. According to a further embodiment, it is proposed that, as the degree of curvature of the arcuate peripheral line of the forming cavity increases, particularly in the angular areas with arches in the shape of a half-round, water cooling is reduced of the copper wall. As a rule, molds are manufactured for the continuous casting of steel in billets and slabs from relatively thin-walled copper tubes. Mechanization of such tubular ingot molds can only be carried out through the pouring orifice or exit hole of the bar. Apart from tubular ingot molds with rectilinear longitudinal axis, they are used in so-called arched continuous casting machines, tubular ingot molds with curved longitudinal axis, which further complicate a machining of the ingot mold cavity. In order to achieve high measurement accuracy, it is proposed, according to a further exemplary embodiment, to fabricate the shaping cavity of the ingot mold by means of a machine tool with numerical control chip removal. BRIEF DESCRIPTION OF THE DRAWINGS In the following, various embodiments of the invention will be described, with reference to the attached figures, in which: Figure 1 is a plan view of a left half of an ingot mold tube according to the state of the technical, for a billet cross-section; Figure 2 is a plan view of a right half of an ingot mold tube according to the invention, for a billet cross-section; Figure 3 is an illustration, on a larger scale, of the corner configuration of an ingot mold tube according to Fig. 2; Figure 4 is an illustration, on a larger scale, of the corner configuration of an ingot mold tube with rectangular cross-section and unequal side lengths; Figure 5 shows peripheral lines of a square conformation cavity cross section; Figure 6 shows an ingot mold with bar scale deformation (Convex Technology); and Figure 7 shows peripheral lines for an essentially circular cross section. DETAILED DESCRIPTION OF THE INVENTION In Figure 1 one half of a tube of copper ingot 2 is illustrated. A peripheral line 3 of a shaping cavity 4 represents the hole of the ingot mold on the casting side and a peripheral line 5 represents the hole of the ingot mold on the exit side of the bar. The peripheral line 5 is smaller than the peripheral line 3, in the measure of a conicity of the shaping cavity 4. A partial section 6 of the peripheral lines 3 and 5 of the cross section of the shaping cavity has a circular line in Angular half-round shape with an angular radius of for example 6 mm. The walls of the ingot mold tube 2, also called walls of the shaping cavity, are water cooled, as is widely known in the state of the art. The degree of curvature 1 / R of a line in arc of circle 7, in the partial section 6 on the casting side, is less than the degree of curvature 1 / R of a line in arc of circle 8, in the partial section 6 on the exit side of the bar.

In FIG. 2, a half of an ingot mold tube 12 with peripheral lines 13 and 15 of a shaping cavity 14 is illustrated. The peripheral line 13 of the cross section of the ingot mold cavity delimits the shaping cavity 14 on the side of pouring and the peripheral line 15 delimits the forming cavity 14 on the exit side of the bar. The peripheral lines 13, 15 and the wall of the shaping cavity are curved, in the angular zones, along sections 16 and are straight along sections 17. Half-round arches in angular zones 19, 19 'are dimensioned in such a way that on either side they occupy at least 10% of the side length 20 of the cross section of the shaping cavity at the outlet of the ingot mold. In the case of a cross section of eg 120 mm x 120 mm the half-round arch occupies on each side at least 12 mm of the side length 20, preferably 18-24 mm or 15-20% of the side length . The peripheral line 13 curved in the angular areas 19 is established by a mathematical curve function with a base parameter and an exponent, which is different from a circular line. The configuration of the angular zone 19 is illustrated in detail in FIG. 3. In FIG. 3 consecutive peripheral lines 23-23"'' 'are illustrated in the direction of advance of the bar in the angular zone 19. The angular zone 19 it can be, in its width, constant from the casting side to the outlet side along the casting cone, and the curved-rectilinear transition points may be arranged on the line R-R4 or on a straight or curved line Rl-R4 . The separations 25-25 '' 'show a continuous conicity of the shaping cavity. The curved peripheral lines 23-23 '' '' and the straight lines 24-24 '' '' represent contour lines of the wall of the shaping cavity. The curved lines are defined by the mathematical function of curve | x | n + |? | N = IR | ?? being established by the choice of the exponent,? n "the degree of curvature of each curved line 23-23". '' One objective in the choice consists in configuring the forming cavity in such a way that the crust of bar in formation is In this case, a symmetrical temperature range must be established uniformly, depending on the configuration of the cross-sectional shape of the bar, a preferential heat penetration can be achieved, in particular by the entire contour of the ingot mold. uniform throughout the contour, in the case of cross sections similar to a circle, solely by the geometry of the cross section of the shaping cavity or, in the case of cross sections of the shaping cavity similar to a rectangle, by a combination of geometry and different cooling along the peripheral line. In the present example the exponent of the curve function is varied as follows: Curved line 23 Exponent "n" 4.0 Curved line 23 'Exponent "n" 3.5 Curved line 23' 'Exponent "n" 3, 0 Curved line 23 '' 'Exponent "n" 2.5 Curved line 23' '' 'Exponent "n" 2.0 (arc of circle) The exponent varies in this example continuously between 4 and 2. According to the election from the conicity of the shaping cavity discontinuous jumps can also be applied. Thanks to a decrease of the exponent between 4 and 2, the degree of curvature of the curved lines decreases or, in other words, the curved lines flatten towards the exit of the ingot mold. This flattening also gives rise to the fact that along a diagonal 26 the conicity of the forming cavity is maximum and decreases towards the rectilinear walls. The degree of curvature of the curved peripheral lines 23-23 '' 'grows to the maximum degree of curvature 30-30' ''. The degree of curvature along the curved peripheral line 23 '' '' is constant (arc of a circle). In the curved section 16 of the angular areas 19, an elimination of the gap between the bar scale that is it moves through the forming cavity and the wall of the forming cavity, and therefore a deformation of the crust of the rod. In Figure 4 an asymmetric corner configuration is illustrated on either side of a diagonal 41. The measure OB is unequal to OA. The curve function of curved lines 42 - 42 '' is n = 1 The curved lines 42-42 '' have in this example the following exponents: Curved line 42 Exponent "n" = 4.0 Curved line 42 'Exponent "n" = 3.4 Curved line 42' 'Exponent,? N "= 3.0 Next to the curved lines 42-42"are provided rectilinear peripheral sections 43 - 43" A conformation cavity wall 44 consists of copper, by triangles 46, 47 with unequal spacing from each other on the outer face A different intensity of cooling is illustrated schematically in the ingot mold: Triangles 46 arranged closer together indicate a greater cooling intensity and triangles 47 with greater separations from each other indicate a lower cooling intensity.

In the example of Figure 5, for the sake of clarity, only three peripheral lines 51-51", consecutive in the forward direction of the bar, of a conformation cavity 50 similar to a square have been illustrated. Each peripheral line is composed of four arched lines, each of which covers an angle of 90 °. The four arched lines correspond to the mathematical function |? | N + |? | N = [R | n. If the casting conicity wt "is also illustrated in the mathematical function, this will be, for example, | x | n + ¡Y¡n = | R ~ t | n This example is based on the following numerical values: According to the choice of the magnitude and the scaling of consecutive exponents in the forward direction of the bar, the peripheral line can be configured in such a way that, at least in a partial section of the ingot mold, between the angular zones configured as an average cane, a deformation of the bar scale during its passage to through the ingot mold by a corresponding choice of the exponent of consecutive curved lines. In the example of FIG. 5, for the achievement of a deformation of the bar scale, particularly between the angular zones (Convex Technology) in the middle of the mold corresponding to the casting side, the exponent "n" of the two consecutive arcs 51 and 51 'in the forward direction of the bar of for example 4 to 5. In the middle of the ingot mold corresponding to the exit side of the bar is achieved, between the two curved lines 51' and 51 '' consecutive in the forward direction of the bar and by a reduction of the exponent of for example 5 to 4.5, a pre-set, uniform heat penetration, essentially without any deformation of the bar crust. This example shows that the penetration of the pre-set heat can be achieved, in consecutive curved lines in the forward direction of the bar, by increasing the exponent in a first section of ingot mold and reducing the exponent in a second section of ingot mold, that is, by adapting the geometry of the shaping cavity. On the other hand, it is however also possible to achieve the penetration of the pre-set heat, with or without deformation of the bar crust, by a different cooling along the peripheral line, depending on the geometry of the curved peripheral line.

Figure 6 shows a tubular copper ingot mold 62 for the continuous casting of steel for a billets or slabs bar, comprising a forming cavity 63. The cross-section of the forming cavity 63 is square at the exit of the ingot mold, and between adjacent side walls 64-64"'' are provided angular zones 65-65 '' 'configured as a half-round. The half-round arcs are not configured as a circular line, but have a curve shape according to the mathematical function | x | n + |? | N = | R j n, presenting the exponent "n" a value between 2.0 and 2.5. On the casting side of the ingot mold, in this example, the arched form of the half-round arch 67 is formed with an exponent n = 2, 2 and on the exit side of the ingot mold the arched shape of the arch in half-round is configured. with an exponent n = 2.02, that is to say that the arched form is, on the exit side of the bar, very close to an arc of a circle. If the convex curvature is carried out in the form of a cosine, the arched form of the half-round arch can be realized with an exponent "n" comprised between 3 - 10. In the exemplary embodiment of Figure 6 the side walls 64-64" In the upper part of the mold cavity and in a partial section of the ingot mold 62, for example in 40% -60% of the length of the ingot mold, concave shape are formed in the forming cavity 63. In this Partial section The height 66 of the arch decreases in the forward direction of the bar. A bar that is formed in the mold with a convex bar crust will be slightly deformed continuously in said partial length, until the arc becomes a straight line. In the second lower half of the mold, the peripheral lines 61, 69 of the forming cavity 63 are rectilinear. In this part of the ingot mold, the forming cavity is provided with a conicity corresponding to the contraction of the cross section of the bar in this part of the ingot mold. The choice of the exponent, n "is made, in molds with convex side walls, in such a way that the extension of the rope as the height of the arc decreases does not exert any prejudicial pressure on the bar scale that is solidifying in the angular zones 65-65 '' 'and the thermal flux in the rounded angular zones 65-65' '' is adapted to the penetration of the heat of the essentially rectilinear walls.An additional adaptation of the heat penetration can be achieved by various cooling of the walls of the shaping cavity along the peripheral line of the cross section of the ingot mold cavity In Figure 7 three peripheral lines 71-73 are illustrated schematically for a circular shaping cavity 70 on the exit side of the mold cavity. the ingot mold. peripherals 71 and 72 are composed of four curved lines, which in this example cover an angle of 90 °. These curved lines correspond to the mathematical function of curve | x | n + | Y | n = | R | n and the value of the exponent? N "of curved lines 71 and 72 is 2.2 and 2.1, respectively. The peripheral line 73 at the exit of the ingot mold is circular.In a partial upper section of the ingot mold with cross-section of the cavity of conformation similar to a circle can be determined, by increasing the difference of the exponent of the curve function between the curved lines 71 and 72, a measure for the plastic deformation of the bar scale in formation in the upper half of the ingot mold The measurement of the plastic deformation is co-determinant for the penetration of heat between the bar scale and the ingot mold wall All the shaping cavities in Figures 1 - 7 have been provided, for reasons of simplification, a rectilinear longitudinal axis Mudguards for arched continuous casting installations have a curved longitudinal axis with a radius, as a rule, between 4 m and 12 m. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (11)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. Shaping cavity of an ingot mold for the continuous casting of billets, slabs and pouches, in which peripheral lines of the cross section of the cavity The shaping sections comprise, at least in the angular regions of the cross section of the forming cavity, curved sections and the walls of the shaping cavity being cooled, characterized in that the peripheral lines present, in the angular zones of the shaping cavity, curved in half-round shape and for the government of an objective deformation of the bar scale, curvatures that increase to a maximum degree of curvature (1 / R) and then decrease again, and because the maximum degree of predetermined curvature of consecutive peripheral lines , in the forward direction of the bar, of said angular areas, decreases continually ua or discontinuous at least along a partial stretch of the ingot mold length.
2. 2. Shaping cavity according to claim 1, characterized in that the curved lines correspond to a mathematical curve function = 1 and, specifically, when A = B to the curve function | x | n + | Y | n = | R | n, and the exponent "n" is greater than 2 and less than 100.
3. 3. Consistency cavity of conformity with claim 1, characterized in that the cross-section of the shaping cavity is similar to a rectangle, preferably similar to a square, and comprises angular zones configured as a half-round between four essentially flat side walls, and because the arcs in average rod in the angular areas correspond to the function of curve | x | n + | Y | n = | R | n and the value of the exponent "n" is between 2.1 and 10.
4. 4. Shaping cavity in accordance with the claim 1, characterized in that the cross-section of the shaping cavity is similar to a rectangle and is composed of four curved lines, each one encompassing approximately an angle of 90 °, and because the curved lines correspond to the mathematical function = 1 and the value of the exponent "n" is between 3 and 50, preferably between 4 and 10.
5. 5. Shaping cavity according to claim 1, characterized in that the cross section of the shaping cavity is similar to a circle and is composed of curved lines, each comprising an angle comprised between 15 and 180 °, and because the curved lines correspond to the mathematical function | x | n + | Y | n = | R | n and the value of the exponent "n" is greater than 2 and less than 2.3.
6. 6. Shaping cavity according to claim 1, characterized in that the cross-section of the shaping cavity is similar to a square and is composed of four curved lines, each covering an angle of 90 °, and because the curved lines correspond to the mathematical function | x | n + | Y | n = | R- | n Y because at least in a partial section of the ingot mold and in a portion of the peripheral line arranged between the angular zones configured as a half-round a deformation of the bar crust is governable, during its passage through the ingot mold, by a flattening of the section of the curved lines.
7. Shaping cavity according to one of Claims 1 to 6, characterized in that the forming cavity is provided, in the direction towards the exit of the ingot mold, with a casting conicity according to the mathematical function | x | n + | Y | n = | R "" t | n, where t is a measure for conicity.
8. 8. Shaping cavity according to claim 1, characterized in that the shaping cavity is similar to a rectangle, preferably similar to a square, and comprises angular zones shaped like a half-round with half-round arches according to the curve function. | n + |? | n = | R | n, and the value of the exponent "n" of consecutive curved lines, in the forward direction of the bar, is comprised between 2.1 and 10, as well as arched side walls between the half-round arches, whose degree of curvature is flattened , at least in a partial section of the ingot mold, in such a way that the bar scale is plastically deformed during its passage through said partial section. .
9. Shaping cavity according to one of claims 1 to 8, characterized in that the shaping cavity is associated with a tubular mold.
10. Shaping cavity according to one of claims 1 to 9, characterized in that the ingot mold consists of copper walls cooled by water, and that as the degree of curvature of sections of the curved peripheral line of the cavity of the cavity increases. conformation, particularly in the angular areas with half-round arches, reduces the water cooling of the copper wall.
11. 11. Mud according to one of claims 1 - 10, characterized in that the geometry of the forming cavity is obtained by a machine tool with chip removal governed by numerical control.