US20160311014A1 - Casting Mould for Casting Steel Melt - Google Patents
Casting Mould for Casting Steel Melt Download PDFInfo
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- US20160311014A1 US20160311014A1 US15/104,696 US201415104696A US2016311014A1 US 20160311014 A1 US20160311014 A1 US 20160311014A1 US 201415104696 A US201415104696 A US 201415104696A US 2016311014 A1 US2016311014 A1 US 2016311014A1
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- Prior art keywords
- casting mould
- casting
- surface texture
- mould
- melt
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/041—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds for vertical casting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/055—Cooling the moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/057—Manufacturing or calibrating the moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/059—Mould materials or platings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
- B22D11/1282—Vertical casting and curving the cast stock to the horizontal
Definitions
- the invention relates to a casting mould for casting steel melt into a strand being continuously drawn, wherein on at least one of the inner surfaces of the casting mould facing towards the melt to be cast a surface texture is formed, which extends at least over the region of the mould, which, during operation, is wetted with slag floating on the melt that has been poured into the mould.
- steel melt is poured from a casting ladle into a distributor, also known as “tundish”, provided as a buffer and, where appropriate, to distribute the melt into several strands, and is transported from there into the respective casting mould by means of a dip tube.
- a distributor also known as “tundish”
- the pouring direction corresponds to the force of gravity here.
- the strand is formed in the casting mould.
- the melt begins to solidify such that the strand coming out of the casting mould in a vertical direction has a thin shell of solidified steel on its outer surfaces, the shell enclosing the still liquid melt inside the strand.
- the strand After emersion from the mould, the strand is redirected supported by rolls in a so-called ‘casting bow’ in a horizontal direction of flow. Systematically controlled cooling takes place in the region of the casting bow in order to effect a controlled solidification of the strand. From the strand being completely solidified and discharged in a horizontal direction slabs are then separated, which and conveyed for further processing.
- Casting powder is scattered in the mould on the free surface of the melt to form slag.
- the slag covers the melt and prevents the melt from reacting with the surrounding atmosphere in the region of the so-called ‘meniscus’.
- the slag binds impurities ascending in the melt and acts as a lubricant between the solidifying shell of the steel strand and the mould.
- the latter technique is applied particularly in billet or circular continuous casting.
- the mould is generally moved in an oscillating manner in order to prevent the steel from sticking to the cooled walls of the mould and to support the discharge of the strand from the mould.
- Continuous casting moulds can be composed of mould plates or designed as one individual piece.
- the internal sides of continuous casting moulds are generally made of copper.
- the inner surfaces of said casting moulds that come into contact with the forming strand can be covered with a nickel coating (EP 0 125 509 B1).
- the nickel coating results in a significant reduction in heat flow. For this reason it is generally applied only at a certain distance from that upper edge of the casting mould, which is assigned to the distributor of the continuous casting plant.
- the steel melt cools particularly rapidly especially in the region of the meniscus. This can lead to surface defects in the case of sensitive steel grades due to the internal stresses that occur during the cooling process.
- EP 1 099 496 B1 suggests reducing the thermal resistance in the region of the meniscus by roughening the mould surface.
- the strand shell forming in the mould should remain thinner for longer and be pressed evenly against the copper plate of the continuous casting mould by the ferrostatic pressure rising with increasing distance from the level of the molten metal.
- the surface of the mould is roughened in the process such that the machining depth of the roughness of the inner surface of the mould decreases in the casting direction such that a gradual transition is achieved from rough to smooth section of the mould and thus also a gradual transition from restricted to unrestricted thermal flow.
- the macrostructure of the inner surface of the mould can be achieved by methods known per se such as shot blast texturing (SBT), electric discharge texturing (EDT), electron beam texturing (EBT), laser texturing (LT) or by a perforated texture (GLT) or using other methods.
- SBT shot blast texturing
- EDT electric discharge texturing
- EBT electron beam texturing
- LT laser texturing
- GLT perforated texture
- the object of the invention was to create a casting mould where with simple means an optimum solidification behaviour is guaranteed in the region of the casting mould that is critical in terms of the risk of crack formation.
- a surface texture is formed on at least one of the inner surfaces of the casting mould facing towards the melt to be cast in accordance with the prior art explained above.
- the surface texture extends at least over the region of the mould, which, during operation, is wetted with slag floating on the melt poured into the mould.
- said surface texture is now designed as a closed structure with indentations which are completely bordered and randomly distributed indentations.
- the structure provided as surface texture according to the invention and formed from entirely defined indentations reduces the transfer of heat between mould and liquid melt.
- Some of the solidifying slag covers the indentations on the random surface structure and sticks there unlike in the case of open surface structures.
- the slag adhering to the inner surface of the mould acts as heat insulation which prevents direct contact of the melt with the inner surface.
- Said insulating effect of the slag layer leads to a lower, and over the breadth of the mould, to a more uniform heat supply in the region of the meniscus.
- fewer internal stresses occur in the strand shell during the cooling process when using a structured mould surface according to the invention compared with a conventional mould surface. Consequently, the risk of surface defects forming is reduced.
- the surface texture described here is wetted.
- the oil layer then adhering in the indentations also acts as thermal insulation.
- the closed surface structure provided according to the invention is, however, characterised by indentations and cavities that are not connected. It turns out that said closed, and according to the invention randomly distributed, indentations ensure better slag adhesion and prevent slag run off.
- the mean roughness index Ra and the mean roughness depth Rz are important in terms of designating said surface structure. Both the mean roughness index Ra and the mean roughness depth Rz must be determined in accordance with DIN EN ISO 4287. In the case of a surface structure according to the invention, the ideal mean roughness index Ra is between 10 m and 50 ⁇ m and the mean roughness depth Rz between 80 ⁇ m and 250 ⁇ m. Mean roughness values and mean roughness depths in said value ranges result in a maximum reduction of surface defects and stable process reliability. This applies particularly if the mean roughness index Ra is between 10 ⁇ m and 50 ⁇ m, in particular between 15 ⁇ m and 50 ⁇ m.
- Optimum adhesion of the slag on the surface texture is produced if the maximum depth of indentations of the surface texture is 500 ⁇ m.
- the indentations should be at least 5 ⁇ m deep in order to reliably achieve the pursued roughness.
- Casting moulds of the type referred to here are normally made of a non-ferrous metal alloy, which is generally cooled on the side facing away from the melt.
- the mould cross-section can be designed as square or rounded.
- at least one of the plates defining the narrow sides of the mould opening can be adjustable in the width direction (EP 0 985 471 A1 ).
- the surface structure provided according to the invention is provided on at least one of the inner surfaces defining the casting mould openings. Naturally, this includes the option to form a corresponding surface structure on all or at least opposite inner surfaces of the casting mould. Also in the case of width-adjustable casting moulds, the surface texture structured according to the invention should be present on at least one of the inner surfaces. The region, which is covered during adjustment of the side of the mould moved relative to said inner surface, can remain free of the surface structure according to the invention if this is advantageous in terms of sealing the corner regions in which the surfaces defining the mould opening touch.
- the surface texture extends over the width of the inner surface provided with said surface texture, by means of which the inner surface comes into contact with the melt to be cast if the smallest thickness or width of the casting mould is configured.
- the surface texture structured according to the invention should extend at least over the region of the respective inner surface of the casting mould, which is wetted during casting operations by the slag covering the meniscus. It has proven useful in the case of casting moulds used today if the surface texture extends over an area which, measured in the casting direction, begins at a distance of at least 10 mm below the upper mould edge and ends at a maximum distance of 600 mm.
- the inner surface provided with the surface structure is covered with a layer of nickel over a section beginning at a distance from the upper edge of the mould, it has proven particularly advantageous in terms of reducing surface defects in the casting strand if the surface texture designed according to the invention overlaps the edge region assigned to the upper edge of the mould. In practice, overlapping areas have proven useful here, which, measured in the casting direction, are at least 50 mm. The overlapping of the surface texture according to the invention with the nickel coating prevents an abrupt break in thermal conductivity in the transition zone between the non-coated to the nickel-coated section of the respective inner surface.
- the structure according to the invention of the surface texture provided on the respective mould surface can be introduced into the surface by embossing (pressure) or by strike or impact momentum, using needles, for example.
- the structure is introduced by deforming the mould surface without removing material in the process.
- the cold work hardening effected as a result of the striking or pressing strain on the respective mould inner surface can contribute towards a longer useful life of the mould.
- a stamping method is used, a negative of the structure to be produced is applied to a matrix, a sphere or a roller. Said negative is then used to apply the surface structure to the mould, depending on pressure and tool surface. If the structure is produced using a method based on strike or impact momentum, the structure defined according to the invention is produced by a tool striking with high momentum. So-called ‘needles’ with which specific surface roughnesses can be generated are suitable for this, such as in DE 199 07 827 A1, for example.
- FIG. 1 shows a side view of a strand casting plant
- FIG. 2 shows a longitudinal section of a casting mould used in the strand casting plant according to FIG. 1 ;
- FIG. 3 shows a perspective view enlarged 7.5 times of section of a surface texture provided according to the invention.
- the steel melt M is transported in a ladle 2 to a distributor 3 and poured into the distributor 3 by means of a ladle shroud 4 .
- a further vertically aligned dip tube 5 is connected, which can be closed and controlled by a stopper 6 .
- the steel melt M flows into a casting mould 7 , which is composed of cooled plates 8 , 9 , 10 , 11 , which are made of a non-ferrous metal or a non-ferrous metal alloy.
- a casting mould 7 has an opening cross-section that is substantially rectangular when viewed from above. The long sides of said cross-section are respectively delimited by a wide mould plate 8 , 9 and the short sides respectively delimited by a narrow mould plate 10 , 11 .
- the mould plates 8 - 11 can often be covered with a nickel layer 14 , which, measured in the vertically aligned direction of flow F of the steel melt M, begins at a variable distance from the upper edge 15 of the casting mould 7 assigned to the distributor 3 .
- the distance A 1 is 300 mm in this case, but can be configured as generally variable.
- a rectangular mould with a nickel layer is used as an example here. However, other mould shapes with different coatings are also possible.
- the strand S forming in the casting mould 7 from the steel melt M comes out of the casting mould 7 in a vertical direction of flow F and is guided in a horizontal direction Fh by means of a casting bow 16 .
- the strand is guided by rollers 19 , 20 .
- Intensive cooling takes place at the same time such that the strand S has completely solidified to the greatest possible extent by the time it reaches the end of the casting bow 16 and can be conveyed for further processing.
- a surface texture 22 is configured on the inner surfaces 13 of the mould plates 8 - 11 defining the mould opening 12 in a section 21 assigned to the upper edge of the mould 15 .
- the surface texture 22 begins in the direction of flow F at a distance A 2 of 10 mm and ends at a distance A 3 of 400 mm from the upper edge of the mould 15 . Accordingly, the surface texture 22 overlaps the nickel layer 14 in an overlapping region U over a length measured in the direction of flow F of 100 mm.
- the surface texture can generally also be introduced up to a distance A3 of 600 mm as seen from the upper edge of the mould 15 .
- the slag K floating at the meniscus of the melt M to be cast during casting operations wets the inner surface 13 of the copper plates 8 - 11 .
- the surface texture 22 is formed by a plurality of indentations 23 , which are each completely enclosed by a partition wall 24 .
- Each partition wall 24 defines two adjacently arranged indentations 23 .
- the indentations 23 can be formed as individual hole-like impressions with a substantially round opening cross-section or from several such impressions merging together, which are then in turn bordered by a self-contained partition wall 24 encircling the respective indentation 23 .
- Material ridging which is produced when using the shot-blasting method, for example, is undesirable in this structure as said ridging is worn down by the strand shell. This would result in a degeneration of the structure reducing the roughness properties.
- Indentations are rather introduced into the mould material in order to achieve cold work hardening and maintain the surface structure.
- the width B of the surface texture 22 is restricted to the narrowest region, which, if the mould plates 10 , 11 defining the mould opening 12 on the short sides thereof are moved, is not covered by the copper plates 10 , 11 .
- the indentations 23 being up to 500 ⁇ m deep have been produced by needles, using a standard needle device, that is not shown here.
- the needles in the needle device have been driven into the inner surface using high force and have compacted the material with which they have come into contact thus forming the respective indentation 23 . No material abrasion occurred.
- the following parameters were set:
- the mean roughness depth Rz and mean roughness index Ra for two surface textures produced in this way inside and outside the overlapping region of surface texture 22 and nickel layer 14 of the inner surfaces 13 are shown in Table 1.
Abstract
A casting mould for casting steel melt into a continuously drawn strand is provided herein. A surface texture is formed on at least one inner surface of the casting mould facing towards the melt to be cast. The surface texture extends at least over region of the casting mould which, during operation, is wetted with slag floating on the melt that has been poured into the casting mould. The casting mould allows optimum solidification behaviour in the region of the casting mould that is critical in terms of the risk of crack formation. The surface texture is designed as a closed structure with self-contained, randomly distributed indentations.
Description
- The invention relates to a casting mould for casting steel melt into a strand being continuously drawn, wherein on at least one of the inner surfaces of the casting mould facing towards the melt to be cast a surface texture is formed, which extends at least over the region of the mould, which, during operation, is wetted with slag floating on the melt that has been poured into the mould.
- In continuous casting, steel melt is poured from a casting ladle into a distributor, also known as “tundish”, provided as a buffer and, where appropriate, to distribute the melt into several strands, and is transported from there into the respective casting mould by means of a dip tube. The pouring direction corresponds to the force of gravity here.
- The strand is formed in the casting mould. Upon contact with the cool inner surfaces of the casting mould the melt begins to solidify such that the strand coming out of the casting mould in a vertical direction has a thin shell of solidified steel on its outer surfaces, the shell enclosing the still liquid melt inside the strand.
- After emersion from the mould, the strand is redirected supported by rolls in a so-called ‘casting bow’ in a horizontal direction of flow. Systematically controlled cooling takes place in the region of the casting bow in order to effect a controlled solidification of the strand. From the strand being completely solidified and discharged in a horizontal direction slabs are then separated, which and conveyed for further processing.
- Casting powder is scattered in the mould on the free surface of the melt to form slag. The slag covers the melt and prevents the melt from reacting with the surrounding atmosphere in the region of the so-called ‘meniscus’. At the same time the slag binds impurities ascending in the melt and acts as a lubricant between the solidifying shell of the steel strand and the mould. Alternatively, there are casting methods in which pre-molten casting powder is fed or in which the casting method uses so-called ‘casting oils’ i.e. liquid casting media, instead of casting powder. The latter technique is applied particularly in billet or circular continuous casting. The mould is generally moved in an oscillating manner in order to prevent the steel from sticking to the cooled walls of the mould and to support the discharge of the strand from the mould.
- Continuous casting moulds can be composed of mould plates or designed as one individual piece. The internal sides of continuous casting moulds are generally made of copper. To improve their resistance to wear and tear the inner surfaces of said casting moulds that come into contact with the forming strand can be covered with a nickel coating (EP 0 125 509 B1). However, the nickel coating results in a significant reduction in heat flow. For this reason it is generally applied only at a certain distance from that upper edge of the casting mould, which is assigned to the distributor of the continuous casting plant.
- Regardless of whether or not the inner surfaces of casting moulds are nickel coated, in the continuous casting method the steel melt cools particularly rapidly especially in the region of the meniscus. This can lead to surface defects in the case of sensitive steel grades due to the internal stresses that occur during the cooling process.
- This issue was already addressed in EP 1 099 496 B1. Reference is made there to the publication ‘Über den Zusammenhang zwischen Anfangserstarrung and Beschaffenheit der Strangoberfräche bei peritektisch erstarrenden Stählen’ (Postdoctoral thesis by M. M. Wolf, Forch 2002, pages 61-64) according to which in particular the thermal flow through the mould wall in the region of the molten metal level thereof plays a crucial role in terms of the absence of cracks in the strand shell. If the heat flow is too great, this results in an increased risk of cracking. In order to increase the thermal flow between the forming strand shell and the inner surface of the mould, EP 1 099 496 B1 suggests reducing the thermal resistance in the region of the meniscus by roughening the mould surface. In this way, the strand shell forming in the mould should remain thinner for longer and be pressed evenly against the copper plate of the continuous casting mould by the ferrostatic pressure rising with increasing distance from the level of the molten metal. The surface of the mould is roughened in the process such that the machining depth of the roughness of the inner surface of the mould decreases in the casting direction such that a gradual transition is achieved from rough to smooth section of the mould and thus also a gradual transition from restricted to unrestricted thermal flow. One advantage considered there is that the macrostructure of the inner surface of the mould can be achieved by methods known per se such as shot blast texturing (SBT), electric discharge texturing (EDT), electron beam texturing (EBT), laser texturing (LT) or by a perforated texture (GLT) or using other methods.
- In the light of the above-mentioned prior art, the object of the invention was to create a casting mould where with simple means an optimum solidification behaviour is guaranteed in the region of the casting mould that is critical in terms of the risk of crack formation.
- This problem is solved according to the invention by a casting mould designed according to Claim 1.
- Advantageous embodiments of the invention are stated in the dependent claims and explained in detail below along with the general inventive concept.
- In a casting mould according to the invention for casting steel melt into a strand being continuously drawn, a surface texture is formed on at least one of the inner surfaces of the casting mould facing towards the melt to be cast in accordance with the prior art explained above. The surface texture extends at least over the region of the mould, which, during operation, is wetted with slag floating on the melt poured into the mould.
- According to the invention, said surface texture is now designed as a closed structure with indentations which are completely bordered and randomly distributed indentations.
- The structure provided as surface texture according to the invention and formed from entirely defined indentations reduces the transfer of heat between mould and liquid melt. Some of the solidifying slag covers the indentations on the random surface structure and sticks there unlike in the case of open surface structures. Thus, the slag adhering to the inner surface of the mould acts as heat insulation which prevents direct contact of the melt with the inner surface. Said insulating effect of the slag layer leads to a lower, and over the breadth of the mould, to a more uniform heat supply in the region of the meniscus. As a consequence of the overall reduced and more uniform heat supply, fewer internal stresses occur in the strand shell during the cooling process when using a structured mould surface according to the invention compared with a conventional mould surface. Consequently, the risk of surface defects forming is reduced. If casting oils are used, the surface texture described here is wetted. The oil layer then adhering in the indentations also acts as thermal insulation.
- An open surface and roughness structure created using the method referred to in EP 1 099 496 B1, for example, or by shot blasting or similar methods, in which the respective indentations overlap and accordingly are not defined from each other, but merge together, obtains its roughness from elevations in the material, which occur due to a shifting of the mould material. The closed surface structure provided according to the invention is, however, characterised by indentations and cavities that are not connected. It turns out that said closed, and according to the invention randomly distributed, indentations ensure better slag adhesion and prevent slag run off.
- In addition to the topographical appearance that occurs in this manner, the mean roughness index Ra and the mean roughness depth Rz are important in terms of designating said surface structure. Both the mean roughness index Ra and the mean roughness depth Rz must be determined in accordance with DIN EN ISO 4287. In the case of a surface structure according to the invention, the ideal mean roughness index Ra is between 10 m and 50 μm and the mean roughness depth Rz between 80 μm and 250 μm. Mean roughness values and mean roughness depths in said value ranges result in a maximum reduction of surface defects and stable process reliability. This applies particularly if the mean roughness index Ra is between 10 μm and 50 μm, in particular between 15 μm and 50 μm.
- Optimum adhesion of the slag on the surface texture is produced if the maximum depth of indentations of the surface texture is 500 μm. The indentations should be at least 5 μm deep in order to reliably achieve the pursued roughness.
- Casting moulds of the type referred to here are normally made of a non-ferrous metal alloy, which is generally cooled on the side facing away from the melt. The mould cross-section can be designed as square or rounded. In order to produce strands of varying widths when using rectangular or square moulds, at least one of the plates defining the narrow sides of the mould opening can be adjustable in the width direction (EP 0 985 471 A1 ).
- The surface structure provided according to the invention is provided on at least one of the inner surfaces defining the casting mould openings. Naturally, this includes the option to form a corresponding surface structure on all or at least opposite inner surfaces of the casting mould. Also in the case of width-adjustable casting moulds, the surface texture structured according to the invention should be present on at least one of the inner surfaces. The region, which is covered during adjustment of the side of the mould moved relative to said inner surface, can remain free of the surface structure according to the invention if this is advantageous in terms of sealing the corner regions in which the surfaces defining the mould opening touch. Accordingly, in the case of a casting mould, the thickness or width of which can be adjusted by displacing at least one of the sides thereof, the surface texture extends over the width of the inner surface provided with said surface texture, by means of which the inner surface comes into contact with the melt to be cast if the smallest thickness or width of the casting mould is configured.
- The surface texture structured according to the invention should extend at least over the region of the respective inner surface of the casting mould, which is wetted during casting operations by the slag covering the meniscus. It has proven useful in the case of casting moulds used today if the surface texture extends over an area which, measured in the casting direction, begins at a distance of at least 10 mm below the upper mould edge and ends at a maximum distance of 600 mm.
- In the event that the inner surface provided with the surface structure is covered with a layer of nickel over a section beginning at a distance from the upper edge of the mould, it has proven particularly advantageous in terms of reducing surface defects in the casting strand if the surface texture designed according to the invention overlaps the edge region assigned to the upper edge of the mould. In practice, overlapping areas have proven useful here, which, measured in the casting direction, are at least 50 mm. The overlapping of the surface texture according to the invention with the nickel coating prevents an abrupt break in thermal conductivity in the transition zone between the non-coated to the nickel-coated section of the respective inner surface.
- The structure according to the invention of the surface texture provided on the respective mould surface can be introduced into the surface by embossing (pressure) or by strike or impact momentum, using needles, for example. The structure is introduced by deforming the mould surface without removing material in the process. The cold work hardening effected as a result of the striking or pressing strain on the respective mould inner surface can contribute towards a longer useful life of the mould.
- If a stamping method is used, a negative of the structure to be produced is applied to a matrix, a sphere or a roller. Said negative is then used to apply the surface structure to the mould, depending on pressure and tool surface. If the structure is produced using a method based on strike or impact momentum, the structure defined according to the invention is produced by a tool striking with high momentum. So-called ‘needles’ with which specific surface roughnesses can be generated are suitable for this, such as in DE 199 07 827 A1, for example.
- The invention is explained in greater detail below using drawings relating to an embodiment. Each of the figures represents a schematic view.
-
FIG. 1 shows a side view of a strand casting plant; -
FIG. 2 shows a longitudinal section of a casting mould used in the strand casting plant according toFIG. 1 ; -
FIG. 3 shows a perspective view enlarged 7.5 times of section of a surface texture provided according to the invention. - To cast a steel melt M into a strand S in the strand casting plant 1 shown in
FIG. 1 and constructed in a manner known per se, the steel melt M is transported in aladle 2 to a distributor 3 and poured into the distributor 3 by means of a ladle shroud 4. To a base outlet of the distributor 3 a further vertically aligneddip tube 5 is connected, which can be closed and controlled by a stopper 6. - When the
dip tube 5 is open, the steel melt M flows into a casting mould 7, which is composed of cooledplates wide mould plate 8, 9 and the short sides respectively delimited by anarrow mould plate - On their
inner surfaces 13 respectively assigned to thecasting mould opening 12, the mould plates 8-11 can often be covered with anickel layer 14, which, measured in the vertically aligned direction of flow F of the steel melt M, begins at a variable distance from theupper edge 15 of the casting mould 7 assigned to the distributor 3. The distance A1 is 300 mm in this case, but can be configured as generally variable. A rectangular mould with a nickel layer is used as an example here. However, other mould shapes with different coatings are also possible. - The strand S forming in the casting mould 7 from the steel melt M comes out of the casting mould 7 in a vertical direction of flow F and is guided in a horizontal direction Fh by means of a casting
bow 16. In the region of the castingbow 16 the strand is guided byrollers bow 16 and can be conveyed for further processing. - A
surface texture 22 is configured on theinner surfaces 13 of the mould plates 8-11 defining the mould opening 12 in asection 21 assigned to the upper edge of themould 15. In this embodiment, thesurface texture 22 begins in the direction of flow F at a distance A2 of 10 mm and ends at a distance A3 of 400 mm from the upper edge of themould 15. Accordingly, thesurface texture 22 overlaps thenickel layer 14 in an overlapping region U over a length measured in the direction of flow F of 100 mm. The surface texture can generally also be introduced up to a distance A3 of 600 mm as seen from the upper edge of themould 15. In the section covered by thesurface texture 22, the slag K floating at the meniscus of the melt M to be cast during casting operations wets theinner surface 13 of the copper plates 8-11. - The
surface texture 22 is formed by a plurality ofindentations 23, which are each completely enclosed by apartition wall 24. Eachpartition wall 24 defines two adjacently arrangedindentations 23. Theindentations 23 can be formed as individual hole-like impressions with a substantially round opening cross-section or from several such impressions merging together, which are then in turn bordered by a self-containedpartition wall 24 encircling therespective indentation 23. Material ridging, which is produced when using the shot-blasting method, for example, is undesirable in this structure as said ridging is worn down by the strand shell. This would result in a degeneration of the structure reducing the roughness properties. Indentations are rather introduced into the mould material in order to achieve cold work hardening and maintain the surface structure. In themould plates 8, 9 defining the mould opening 12 on the long sides thereof, the width B of thesurface texture 22 is restricted to the narrowest region, which, if themould plates copper plates - The
indentations 23 being up to 500 μm deep have been produced by needles, using a standard needle device, that is not shown here. The needles in the needle device have been driven into the inner surface using high force and have compacted the material with which they have come into contact thus forming therespective indentation 23. No material abrasion occurred. In order to maintain thestructure comprising indentations 23 andpartition walls 24 shown inFIG. 3 , the following parameters were set: -
- distance between needle device housing and surface to be machined,
- feed speed and feed direction,
- movement pattern of the needle device housing/needle device and
- force with which the needles strike the surface to be machined.
- The mean roughness depth Rz and mean roughness index Ra for two surface textures produced in this way inside and outside the overlapping region of
surface texture 22 andnickel layer 14 of theinner surfaces 13 are shown in Table 1. -
TABLE 1 Sample Sample roughness roughness Nickel- from non- from plated Roughness nickel- nickel- Example mould? parameter plated area plated area 1 No Ra 26.42 μm — Rz 120.34 μm — 2 Yes Ra 22.31 μm 16.99 μm Rz 121.20 μm 95.39 μm 3 Yes Ra 41.28 μm 18.91 μm Rz 187.33 μm 93.66 μm - 1 Continuous casting plant
- 2 Ladle
- 3 Distributor (Tundish)
- 4 Ladle shroud
- 5 Dip tube
- 6 Stopper
- 7 Casting mould
- 8-11 Copper plates
- 12 Casting mould opening
- 13 Inner surfaces of casting mould 7
- 14 Nickel layer
- 15 Upper edge of mould
- 16 Casting bow
- 19,20 Rollers
- 21 Section of the
inner surfaces 13 - 22 Surface texture
- 23 Indentations
- 24 Partition wall
- A1-A3 Distances, measured in direction of flow F
- B Width of section of the
inner surface 13 provided with the surface texture - F Direction of flow of steel melt M in casting mould 7
- Fh Horizontal direction of flow
- K Slag
- M Melt
- S Strand
- Ü Overlapping region
Claims (12)
1. A casting mould for casting steel melt into a continuously drawn strand wherein a surface texture is formed on at least one inner surfaces of the casting mould facing towards the melt to be cast, said surface texture extending at least over a region of the casting mould, which, during operation, is wetted with slag floating on the melt that has been poured into the casting mould, wherein the surface texture is designed as a closed structure with completely bordered, randomly distributed indentations.
2.The casting mould according to claim 1 , wherein the surface texture extends over an area, which, measured in a casting direction, begins at a distance of at least 10 mm below an upper edge of the mould and ends at a maximum distance of 600 mm.
3. The casting mould according to claim 1 , wherein a maximum depth of indentations of the surface texture is 500 μm.
4. The casting mould according to claim 1 , wherein a mean roughness index of the surface texture is between 10 μm and 50 μm.
5. The casting mould according to claim 1 , wherein a mean roughness depth of the surface texture is between 80 μm and 250 μm.
6. The casting mould according to claim 1 , wherein the casting mould has a square or rounded opening cross-section and wherein the surface texture is configured on at least one of the inner surfaces of the casting mould, which defines the opening cross-section on a long side thereof.
7. The casting mould according to claim 6 , wherein the casting mould is width-adjustable by moving a short side thereof and wherein the surface texture extends over a width of the inner surface provided with said surface texture, by means of which the inner surface comes into contact with the melt to be cast, if the casting mould is set to the smallest width.
8. The casting mould according to claim 1 , wherein the surface texture is introduced by impacting the respective inner surface of the casting mould.
9. The casting mould according to claim 8 , wherein the surface texture is introduced into the inner surface using needles.
10. The casting mould according to claim 8 , wherein the surface texture is embossed into the respective inner surface of the casting mould.
11. The casting mould according to claim 1 , wherein the inner surface provided with the surface texture is covered with a layer of nickel over a section beginning at a distance from an upper edge of the mould and wherein the surface texture overlaps an edge region of the nickel layer assigned to the upper edge of the mould.
12. The casting mould according to claim 11 , wherein the surface texture overlaps the nickel layer measured in a casting direction by at least 50 mm.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102013114326.1A DE102013114326A1 (en) | 2013-12-18 | 2013-12-18 | Casting mold for casting molten steel |
DE102013114326.1 | 2013-12-18 | ||
PCT/EP2014/003374 WO2015090564A1 (en) | 2013-12-18 | 2014-12-16 | Casting mould for casting steel melt |
Publications (1)
Publication Number | Publication Date |
---|---|
US20160311014A1 true US20160311014A1 (en) | 2016-10-27 |
Family
ID=52273073
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/104,696 Abandoned US20160311014A1 (en) | 2013-12-18 | 2014-12-16 | Casting Mould for Casting Steel Melt |
Country Status (11)
Country | Link |
---|---|
US (1) | US20160311014A1 (en) |
EP (1) | EP3083103B1 (en) |
JP (1) | JP2016540649A (en) |
KR (1) | KR20160099641A (en) |
CN (1) | CN105828977A (en) |
CA (1) | CA2934379A1 (en) |
DE (1) | DE102013114326A1 (en) |
MX (1) | MX2016007791A (en) |
RU (1) | RU2016128990A (en) |
WO (1) | WO2015090564A1 (en) |
ZA (1) | ZA201603959B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102017113600A1 (en) * | 2017-06-20 | 2018-12-20 | Vishay Electronic Gmbh | power resistor |
CN114882045B (en) * | 2022-07-11 | 2022-09-20 | 山东金三星机械有限公司 | Technological method for milling casting gate |
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- 2014-12-16 US US15/104,696 patent/US20160311014A1/en not_active Abandoned
- 2014-12-16 CN CN201480069185.XA patent/CN105828977A/en active Pending
- 2014-12-16 CA CA2934379A patent/CA2934379A1/en not_active Abandoned
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- 2014-12-16 MX MX2016007791A patent/MX2016007791A/en unknown
- 2014-12-16 JP JP2016541676A patent/JP2016540649A/en active Pending
- 2014-12-16 RU RU2016128990A patent/RU2016128990A/en unknown
- 2014-12-16 EP EP14821067.7A patent/EP3083103B1/en active Active
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Also Published As
Publication number | Publication date |
---|---|
WO2015090564A1 (en) | 2015-06-25 |
EP3083103B1 (en) | 2019-10-16 |
EP3083103A1 (en) | 2016-10-26 |
KR20160099641A (en) | 2016-08-22 |
RU2016128990A (en) | 2018-01-23 |
MX2016007791A (en) | 2016-09-29 |
JP2016540649A (en) | 2016-12-28 |
DE102013114326A1 (en) | 2015-06-18 |
ZA201603959B (en) | 2017-08-30 |
CN105828977A (en) | 2016-08-03 |
CA2934379A1 (en) | 2015-06-25 |
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