Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D5/00—Machines or plants for pig or like casting
  • B22D5/005—Devices for stacking pigs; Pigforms to be stacked
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D7/00—Casting ingots, e.g. from ferrous metals
  • B22D7/005—Casting ingots, e.g. from ferrous metals from non-ferrous metals

Definitions

• the present invention relates to the foundry of non-ferrous metals, in particular aluminum and its alloys. It particularly relates to metal ingots, in particular stackable ingots, and the ingot molds which make it possible to obtain them.
• the metal ingots are produced by pouring liquid metal into a mold of determined shape.
• the liquid metal cools, solidifies and gives an ingot having the shape of the interior volume of the ingot mold.
• the ingots have, for the most part, a shape which allows them to be stored by stacking and the handling of the stacks obtained. Stacks can be stabilized by one or more straps. In general, ingots are also provided with means for limiting the volume of stacks and for self-stabilizing them. These means are typically locking elements ("interlocking means" in English), such as projecting elements (nipples, bosses, studs, ...) and hollow elements (notches, grooves, ...), which cooperate to allow each ingot to be retained by neighboring ingots.
• the speed of the ingot manufacturing process by cooling and solidifying the ingots is a determining factor in the productivity of a foundry.
• a cooling fluid typically water
• the production of ingots can become a step limiting the production of a factory. There is therefore a permanent search for solutions to accelerate the production of ingots, while preserving the quality of the ingots obtained and the possibility of stacking them in a stable manner.
• the subject of the invention is a metal ingot mold, intended for the manufacture of ingots by cooling and solidification of a mass of liquid metal of initial volume Vo, comprising an internal cooling surface S intended for the evacuation of all or part of the thermal energy released by the mass of liquid metal during its cooling and its solidification, and characterized in that the cooling surface S has a shape such that, during the contraction of the volume Vo of metal caused by its cooling and solidification, the metal remains in contact with at least 10% of the surface S.
• the metal remains in contact with at least 15% of the surface S, and more preferably at least 20% of the surface S.
• the Applicant has found that, unexpectedly, the effective cooling time of the ingots, from the pouring of the liquid metal into the ingot mold until the extraction of the solidified ingot, was in fact much longer than expected by the estimates from thermal calculations and that the importance of this phenomenon depended strongly on the shape itself of the mold. She then had the idea that the extension of the cooling was in fact largely due to a problem of thermal contact between the metal and the ingot mold and noted that, against all expectations, the contraction of the metal during its solidification produced, in many places, a slight separation between the ingot and the internal surface of the ingot mold. Although weak, this separation creates an air gap which significantly reduces the heat exchange between the ingot and the wall of the ingot mold. The heat exchanges then take place practically only on very limited surfaces at the interface between the ingot and the ingot mold.
• the metal ingot mold is characterized in that the cooling surface comprises at least one planar surface element Si, preferably forming all or part of the bottom of the ingot mold, in that there exists at least one point C on a plane Pi tangent to the element, or to each element, of surface Si such that all the line segments D connecting any point R of the cooling surface S to point C pass only to l inside the ingot mold, and in that the total area of the element, or elements, of surface Si is at least equal to 10% of the cooling surface S.
• the cooling surface comprises at least one planar surface element Si, preferably forming all or part of the bottom of the ingot mold, in that there exists at least one point C on a plane Pi tangent to the element, or to each element, of surface Si such that all the line segments D connecting any point R of the cooling surface S to point C pass only to l inside the ingot mold, and in that the total area of the element, or elements, of surface Si is at least equal to 10% of the cooling surface S.
• the total area of the element, or elements, with a surface Si is at least equal to 15% of the cooling surface S, and more preferably at least equal to 20% of the cooling surface S.
• the subject of the invention is also a metal ingot, capable of being obtained with an ingot mold according to the invention, comprising a molded surface Sm and a rough surface Sb, and characterized in that the molded surface Sm comprises at least one element of planar surface Si, in that there is at least one point C on a plane Pi tangent to the element, or to each element, of surface Si such that all the line segments D connecting any point R of the molded surface Sm at point C pass only inside the ingot, and in that the total area of the element, or elements, of surface Si is at least equal to 10% of the molded surface Sm.
• the molded surface Sm corresponds to the part of the total surface of the ingot which has been shaped by the ingot mold, namely the initial surface So.
• the rest of the surface of the ingot, or gross surface Sb typically corresponds to the upper part of the initial mass of liquid metal.
• the total area of the element, or elements, with a surface area Si is at least equal to 15% of the molded surface Sm, and more preferably at least equal to 20% of the molded surface Sm.
• the invention also relates to the use of an ingot mold according to the invention for the manufacture of metal ingots.
• the invention also relates to a method for manufacturing metal ingots using an ingot mold according to the invention.
• the invention is particularly suitable for the manufacture of ingots made of non-ferrous metal, in particular aluminum, aluminum alloy, magnesium, magnesium alloy, zinc or zinc alloy.
• Figures 1 and 2 illustrate, viewed in longitudinal section, two molds typical of the prior art and the effect of the contraction of the metal during its cooling and solidification.
• FIG. 3 represents an ingot mold according to the invention.
• FIG. 4 illustrates, viewed in longitudinal section, an ingot mold according to the invention and the effect of the contraction of the metal during its cooling and its solidification.
• Figure 5 illustrates mold profiles according to variants of the invention.
• an ingot mold (1) typically comprises a wall (2), generally made of metal and / or refractory material, and an opening (3) adapted to allow the admission of liquid metal into the ingot mold.
• the wall (2) defines a bottom (4), side walls (2 ') and end walls (2 ").
• the wall (2) has an interior surface (5) and form elements (6, 7, 8) intended to give a specific shape to the ingot These shape elements make it possible, in particular, to obtain locking or handling elements for the ingot.
• the liquid metal (10) initially fills a volume Vo and comes into contact with the wall (2) on a part So of the internal cooling surface S.
• the ratio between the area Ao of the surface So and the volume Vo of the metal liquid is then high, typically of the order of 0.5 cm "1.
• the metal contracts (occupying a volume Vo 'smaller than Vo) and detaches from the wall in several places, thus forming air gaps (9).
• the area Ar of the residual contact surface Sr is significantly smaller than the initial area Ao.
• the Applicant estimates that the area of the residual surface obtained with the ingot molds of the prior art is much less than 10% of the initial area (typically of the order of 5%). , a small reduction in the volume Vo leads to a considerable increase in the resistance e thermal.
• the shape is such that, during the contraction of the volume Vo of metal caused by its cooling and its solidification, the metal remains in contact with at least 10% of the cooling surface S.
• the metal ingot mold (1) which is intended for the manufacture of an ingot (11) by cooling and solidification of a mass of liquid metal (10), has a wall (2) and an opening (3), said wall (2) defining a bottom (4) and an interior surface (5) of which a part S, called the cooling surface, is capable of evacuating all or part of the thermal energy released by the mass of metal (10) during its cooling and solidification, said wall (2) comprising at least one form element (6, 7, 8) intended to form at least one locking element, one element stacking or a handling element on the ingot (11), and is characterized in that the cooling surface S comprises at least one planar surface element Si forming all or part of the bottom (4) of the ingot mold (1) , in that there exists at least one point C on a plane Pi tangent to the element, or to c each element, of surface If such that all the line segments D connecting any point R of the cooling surface S to point C pass only inside the ingot mold (1), and in that the total area of l element
• the line segments D do not touch any other point on the surface S, except those of the surface elements Si.
• the total area of the element, or elements, of surface Si is at least equal to 15% of the surface S, and more preferably at least equal to 20% of the surface S.
• the effect of gravitation is taken into account by the fact that the surface element (s) Si are located at the bottom of the mold.
• point C is preferably such that the center of mass of the contracted volume Vo ', corresponding to the contracted surface So', is at the lowest point possible with respect to the normal direction of use of the ingot mold, c ' that is, it is not possible to move the contracted surface So 'vertically downwards without producing an intersection between So' and the internal surface (5) of the mold.
• the homothetic contraction leaves the contracted surface So 'at the lowest gravitational level relative to the direction of use of the ingot mold.
• the ingot molds according to the invention thus make it possible to maintain a significantly larger residual contact surface than the ingot molds of the prior art.
• the exact value of the quantity K is not critical for the operation of the invention, as long as it is representative of the thermal contraction values obtained with the metals. It is sufficient to use a homothetic ratio K of less than about 1% to determine the appropriate cooling surface shapes.
• the volume contractions of the metal, from Vo to Vo ', shown in the appended figures have been deliberately exaggerated in order to better illustrate the principle of the invention.
• the surface elements Si are advantageously inclined at an angle otj relative to the initial normal level N of the liquid metal (10). Said level N is typically parallel to the outer edge (16) of the opening (3) of the mold (1).
• the angle (Xi is preferably less than 30 °, and preferably less than 20 °, in order to optimize the volume of the ingot while freeing up a space under it which makes it possible to pass a strap during the stacking of the ingots obtained.
• the cooling surface S normally comprises more than 5 distinct surface elements, namely at least two side walls (2 '), two walls of end (2 ") and a bottom (4).
• the mold shown in Figure 3 has at least 10 separate surface elements (including the side walls (2 ')).
• the ingot mold according to the invention typically comprises an even number of surface elements Si.
• the number of surface elements Si is preferably equal to 2 (as illustrated in FIGS. 3 and 4) in order to simplify its production and d 'more easily obtain a very large residual contact area.
• the surface elements Si are preferably contiguous (as illustrated in FIG. 3) in order to make it possible to maximize the residual contact surface.
• FIG. 3 illustrates a particularly advantageous embodiment of the invention in which there are two surface elements Si, denoted Si and S 2 , which are not in the same plane and which intersect at point C.
• the FIG. 5 illustrates variants of the invention in which the bottom (4) comprises additional shaped elements (14, 15).
• the surface elements Si may have different areas Ai and be inclined at a different angle Oj.
• the latter advantageously has a main axis A and a plane of symmetry B perpendicular to its main axis A, and the point C is located in the plane of symmetry B.
• the angle ai is the same for the surface elements Si arranged symmetrically.
• the outer edge (16) of the opening (3) of the mold (1) is preferably substantially straight and perpendicular to the plane B and the normal initial level N of the liquid metal (10) is substantially parallel to said edge. exterior (16).
• none of the angles between the elements of the internal surface of the ingot mold is less than 90 ° in order to avoid forming blocking zones of the ingot in the ingot mold which would hamper its extraction.
• the locking elements typically comprise protruding elements (pins, bosses, studs, etc.) and hollow elements (notches, grooves, etc.), which cooperate to allow each ingot to be retained by the ingots. neighbors.
• the stacking elements typically include protruding or recessed elements (such as recesses) which allow the ingots to be stacked optimally and / or which make it possible to place means for stabilizing the stack, such as straps .
• the handling elements typically comprise protruding and / or recessed elements which form gripping means, such as "ears" or handles.
• the invention also relates to a metal ingot (11) comprising a molded surface Sm and a rough surface Sb, comprising at least one element chosen from the locking elements, the stacking elements and the handling elements and characterized in that the molded surface Sm comprises at least one plane surface element Si, in that there is at least one point C on a plane Pi tangent to the element, or to each element, of surface Si such that all the segments on the right D connecting any point R of the molded surface Sm to point C pass only inside the ingot (11), and in that the total area of the element, or elements, of surface Si is at least equal to 10% of the molded surface Sm.
• a homothetic contraction of the surface Sm does not generate an intersection between the contracted surface Sm 'thus obtained and the molded surface Sm.
• the total area of the element, or elements, with a surface area Si is at least equal to 15% of the molded surface Sm, and more preferably at least equal to 20% of the molded surface Sm.
• Each surface element Si is advantageously inclined at an angle Oj relative to the gross surface Sb of the ingot, which makes it possible to optimize the volume of the ingot while freeing up a space under it which allows a strap to be passed during stacking ingots.
• the angle Oi is preferably less than 30 °, and more preferably less than 20 °.
• the Applicant has noted that the free space thus obtained was particularly advantageous since it makes it possible to use a strap made of flexible material, such as polyester, which ensures good resistance of the stack, when the ingots are stacked, without risking that 'it wears out when handling the stack. Indeed, in the absence of this free space, the strap can rub on the ground and wear by abrasion. It is generally sufficient that the depth H of the free space under the ingot obtained is between 6 and 12 mm for an ingot with a total length of approximately 70 cm.
• the ingot according to the invention typically comprises an even number of surface elements Si, and preferably two surface elements Si in order to simplify its manufacture.
• the two surface elements Si are typically contiguous.
• the ingot has a main axis A and a plane of symmetry B perpendicular to its main axis A, and the point C is located in the plane of symmetry B.
• the angle Oi is the same for the surface elements Si arranged symmetrically.
• the number of surface elements Si is preferably equal to 2 (as illustrated in FIGS. 3 to 5).
• the surface elements Si are preferably contiguous (as illustrated in FIGS. 3 and
• these preferably include handling elements (13), typically two end elements, called “ears”, as illustrated in FIG. 4.
• the ingot according to the invention which is typically a stackable ingot, can be obtained with the ingot mold according to the invention.
• the invention also relates to a method for manufacturing metal ingots in which a volume Vo of liquid metal is poured into an ingot mold according to the invention, the ingot mold is subjected to a flow of cooling fluid (typically water ) and the ingot is extracted after cooling and solidification of the metal.
• a flow of cooling fluid typically water
• the metal is typically aluminum, an aluminum alloy, magnesium, a magnesium alloy, zinc or a zinc alloy.
• the invention makes it possible to obtain ingots free of bubbles and cracks originating from the shrinkage of the metal during its cooling.
• the solidification times were respectively greater than 350 s for the ingot molds of the prior art and of the order of 335 s for the ingot molds according to the invention.
• the solidification times obtained with ingot molds of the prior art were very dispersed (standard deviation greater than 30 s), whereas they were little dispersed with the ingot molds according to the invention (standard deviation less than 3 sec).
• the ingots obtained with the ingot molds according to the invention were generally free from shrinkage and cracks.
• the total internal surface of the ingot molds (including the side walls (2 ′)) of the prior art and according to the invention was approximately 2300 cm 2 .
• the Applicant estimates that the value of the residual contact surface was approximately 5% of the total surface for the ingot molds of the prior art and approximately 20% of the total surface with the ingot molds according to the invention.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Silicon Compounds (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Continuous Casting (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)
• Superconductors And Manufacturing Methods Therefor (AREA)
• Artificial Fish Reefs (AREA)

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Publications (2)

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• 2003
  • 2003-02-18 FR FR0301912A patent/FR2851183B1/fr not_active Expired - Fee Related
• 2004
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