Mould body

Abstract

A mould body (1) for the continuous casting of metal, with a longitudinal direction L between an upper end (4) and a lower end (5), wherein at least a partial region of the outer surface (6) of the mould body (1) is provided with a cooling structure (7) to improve the cooling. The cooling structure (7) has at least one V-shaped region with two limbs at an opening angle with respect to each other and with a point, the point being directed towards the lower end (5).

Description

[0001] mold body

[0002] The invention relates to a mold body for the continuous casting of metals according to the features in the preamble of patent claim 1.

[0003] Mold bodies for continuous metal casting, either alone (mold tube) or in conjunction with other mold bodies (mold plates), define a mold cavity with an upper end and a lower end in the casting direction. The mold body is cooled externally. Mold bodies are usually made of copper and their task is to transport heat from the molten metal inside the mold to the outside. The heat transfer coefficient from the outside of the mold to the cooling medium plays a crucial role here. The cooling medium is usually water, which is circulated in a closed circuit. It flows turbulently along the outer surface of the mold body at a flow velocity typically between 6 and 14 m / s, and sometimes somewhat faster. Heat flux densities in the area of ​​the mold level range from 3 to 7 MW / m 2are common. The cooling water comes into contact with the outer mold wall at a speed of approximately 10 m / s and heats up between 6 and 12 K during this time. The temperatures on the outer mold wall are typically between 120 and 300°C and on the inside between approximately 250 and 450°C. The wall thicknesses of the mold bodies depend on the size. For mold tubes, they are generally 8 to 12% of the casting size and thus have a distance of 10 to a maximum of 35 mm from the cooling water. Mold tubes are typically between 700 mm and 1200 mm long.

[0004] DE 195 08 169 C5 discloses a mold for continuous casting of metals in which the cooling-side surface is provided with a structure with different shapes and / or recesses. The recesses affect the turbulence of the flow. They increase the outer surface of the mold and thus the cooling effect.

[0005] The invention is based on the object of improving a mold body for the continuous casting of metals with regard to the cooling performance.

[0006] This object is achieved by a mold body having the features of patent claim 1.

[0007] The mold body according to the invention for the continuous casting of metals has a longitudinal direction between an upper end and a lower end in the casting direction. At least a partial region of the outer surface of the mold tube is provided with a cooling structure to improve cooling. The cooling structure has at least one V-shaped region with two legs arranged at an opening angle to one another and with a tip, wherein the tip is directed towards the lower end of the mold tube. The orientation of the tip of the V-shaped region is directed in particular against the flow direction of the cooling medium. The V-shaped region is designed as a groove in the outer surface and has a groove width and a groove depth.

[0008] The V-shaped areas in the boundary layer area between the outer surface and the turbulently flowing cooling medium create macrostructures that swirl the cooling medium more strongly and thus cause increased heat transfer and heat removal from the mold tube wall into the cooling medium.

[0009] The geometrically defined V-shaped regions can be described as barriers from a fluid dynamics perspective. They are not individual point-like depressions, but rather V-shaped structures of a defined length and shape which, unlike point-like depressions, cannot be flowed around laterally by the coolant, but can only be flowed over or through. In this sense, the V-shaped regions form "trip wires" for the flow. As a result, they are not rough structures, but rather depressions on the outer surfaces of the mold body in the sense of wave or channel structures or longer grooves. In particular, the stretched length of each individual V-shaped region is greater than the width of one side of the outer surface of a mold tube. The stretched length is the length measured from one end point of the V-shaped region to its other end point when following the course of the V-shaped region.

[0010] The effect of a tripwire for generating turbulent flow can be replicated by arranging several of the V-shaped regions according to the invention one behind the other in the longitudinal direction of the mold body and / or next to each other transversely to the longitudinal direction. Transverse to the longitudinal direction means, in particular, at a 90° angle to the longitudinal direction. The term "transverse" also includes angles other than 90°, with the exception of 0° and 180°.

[0011] The adjusted longitudinal spacing of the V-shaped regions leads to the generation of additional turbulence and vortexes, especially near the surface of the mold body. Furthermore, the V-shaped regions increase the surface area of ​​the mold body's exterior. These factors lead to an improvement in the cooling effect.

[0012] When V-shaped regions are arranged one behind the other in the longitudinal direction, one or more of the V-shaped regions overlap in the longitudinal direction, depending on the opening angle of the V-shaped regions. The opening angle of the V-shaped regions is preferably in a range of 30° to 150°, measured from leg to leg. The opening angle is composed of the two leg angles, each of which is related to the longitudinal direction of the mold body. The leg angles are therefore each 15° to 75°. The leg angles are preferably the same. However, the leg angles can also differ from one another.

[0013] It is possible to arrange several of the V-shaped regions arranged one behind the other in the longitudinal direction, transverse to the flow direction or transverse to the longitudinal direction, next to one another. The number of V-shaped regions arranged next to one another transverse to the longitudinal direction can be 1 to 50, in particular 1 to 10. Preferably, the number of V-shaped regions arranged next to one another is less than 5, and 3 V-shaped regions are preferred.

[0014] The adjacent V-shaped regions can be connected to each other to form a wave structure. The wave structure can be uniform, meaning that all opening angles of the V-shaped regions of the wave structure are the same. In principle, a uniform opening angle can be provided for all V-shaped regions of a mold tube. This allows parallel structures to be created that can be arranged at relatively short distances from one another on the outer surface. In this case, the legs of two V-shaped regions arranged one behind the other in the longitudinal direction run parallel to one another.

[0015] The V-shaped region is formed as a groove in the outer surface. The groove has a groove width measured transversely to the longitudinal direction of the groove and a groove depth. The groove width is preferably in a range of 2 to 10 mm and the groove depth in a range of 0.1 to 2 mm. The groove depth is preferably at least 0.3 mm. For the purposes of the invention, however, groove depths of at least 0.1 mm are no longer to be assigned to the order of magnitude of roughness, but functionally to the range of trip wires. The groove width and the groove depth are preferably constant over the entire length of the groove. Alternatively, the groove depth and / or the groove width vary in adaptation to the local cooling properties.

[0016] The grooves can have a rounded, rectangular or even trapezoidal cross-section. Accordingly, the groove depth can be constant with a rectangular cross-section. With a rounded cross-section, the groove depth is greatest in the middle of the groove. With a trapezoidal cross-section, the groove depth can be greater on one side of the groove onto which the coolant flows than on the other side of the groove. The coolant flows over the first side and swirls within the deepest area of ​​the groove, then flows out of the groove again via the rising groove base on the other side and flows into the next groove. In general, in addition to increasing the surface area, the grooves have the effect of reducing the average distance between the coolant and the surface to be cooled, i.e. the inside of the mold body. This locally increases the cooling effect.

[0017] The distance between the parallel legs of adjacent V-shaped regions preferably corresponds to at least the groove width. It is preferably 2 to 10 mm. The distance should be selected such that additional microturbulence is generated near the surface. This turbulence increases the cooling effect.

[0018] A particularly large amount of heat must be dissipated in the meniscus area of ​​a mold, i.e. the mold body, wherein the meniscus area is adjacent to the upper end. The meniscus area is the area in which the meniscus level of the molten metal is located during casting. The cooling structure should therefore extend over a maximum of 30% of the length, adjacent to the upper end. In the further area of ​​the mold tube, the cooling structures according to the invention are not required. It is therefore more advantageous from a manufacturing perspective to arrange cooling structures only in an area of ​​approximately 30% of the length adjacent to the upper end. The cooling structure should also begin at a distance of less than 50 mm from the upper end of the mold tube.

[0019] In a special embodiment of the cooling structure, it is extended to the sides, e.g., toward the corners of a mold tube or toward the edges of a mold plate, with the depth of the grooves decreasing toward the sides. Similarly, the cooling structure can also be extended in the casting direction, i.e., with the depth of the grooves decreasing incrementally. This creates a smoother transition between areas with and without a cooling structure. In this case, the cooling structure can also extend over larger areas than the aforementioned 30% in the meniscus area or 30% below the calculated casting level of the mold body.

[0020] Additionally or optionally, the V-shaped area can also be made narrower in the casting direction by gradually making the legs shorter, so that they are geometrically less significant, i.e. smaller and possibly also less deep.

[0021] If the mold body is designed as a mold plate, several sub-areas can be provided with the described cooling structure, especially hot spots where the heat load is particularly high. Such sub-areas can begin at a distance of 30% of the length of the mold plate or be arranged adjacent to the lower end.

[0022] A special design can be realized for round mold tubes, namely a cooling structure that runs over 360° in the area of ​​the meniscus, so that the cooling structure is arranged over the entire circumferential area.

[0023] The mold tube according to the invention is intended in particular for the production of rectangular format cross-sections. In this case, the mold tube has an outer surface with multiple sides. Cooling structures can be arranged on several of the sides, in particular on all sides. In principle, it is possible for identical cooling structures to be attached to all sides. However, the invention also takes into account that the sides have different cooling structures, whereby the differences can lie in the number and size of the individual grooves. In principle, it is also possible to use cooling structures on the individual sides with different opening angles. In a mold plate with cooling structures in multiple sub-regions, the cooling structures can differ from one another in their shape and size, as explained above for a mold tube.

[0024] To generate the turbulence, an advantageous development of the invention provides for at least one elevation to be formed on the outer surface upstream of a groove in the direction of flow and optionally additionally downstream of it in the direction of flow. The elevation can extend over part of the length of the groove and preferably over the entire length of the groove. In particular, it is directly adjacent to the groove. The elevation preferably protrudes 0.1 - 2 mm, in particular 0.1 - 1 mm, from the outer surface outside the groove. The grooves can be produced by a rolling process. When rolling in the grooves, displaced material can be used to generate the at least one elevation. The elevations have, in particular, a bead-shaped, rounded cross-section.

[0025] The invention provides a mold body (mold tube, mold plate) for casting molten metals, which is made in particular of copper or a copper alloy and has an increased heat transfer coefficient in the area of ​​highest thermal stress, the meniscus region, while efficiently equalizing different cooling capacities, particularly around the circumference of a mold tube. Taking into account the specific operating conditions of mold tubes or mold plates, V-shaped channel structures, whose tips point opposite to the flow direction of the cooling medium, have proven advantageous.

[0026] The mold bodies according to the invention otherwise correspond to the molds of the designs mentioned above, i.e. they are used in conjunction with a cooling medium that is guided in a closed circuit and has flow velocities between 6 and 14 m / s on the mold's outer surface, with heat flux densities in the meniscus region of 3 to 7 MW per square meter. Typical lengths of mold bodies in the form of mold tubes are between 700 and 1200 mm. The cooling water is in contact with the mold body for approximately 100 ms. During this contact time with the mold tube, it heats up by 6 to 12 K. The mold wall temperatures of the mold body according to the invention are typically 120 to 300°C on the outside and 250 to 450°C on the inside. The mold body wall thicknesses depend on the format and are usually 8 to 12% of the casting format and are preferably between 10 and 35 mm.

[0027] The invention is explained below with reference to exemplary embodiments illustrated in schematic drawings. Figure 1 shows a perspective view of a mold body in the form of a mold tube in a first embodiment;

[0028] Figure 2 is a side view of the upper end of the mold tube of Figure 1;

[0029] Figure 3 shows a second embodiment of a mold body in a perspective view;

[0030] Figure 4 shows the mold body of Figure 3 in a side view in the area of ​​the upper end;

[0031] Figure 5 is a sectional view through a groove of the mold body of Figure 4;

[0032] Figure 6 is a sectional view through a second embodiment of a groove and

[0033] Figure 7 is a sectional view through a third embodiment of a groove;

[0034] Figure 8 is a sectional view through a fourth embodiment of a groove

[0035] Figure 9 shows a mold body in the form of a mold plate and

[0036] Figure 10 shows the mold body of Figure 9 in a perspective view.

[0037] Figure 1 shows a mold body 1 in the form of a mold tube for the continuous casting of metal. The mold body 1 has a rectangular cross-section and, with its wall 3, defines a rectangular mold cavity 2 that extends from an upper end 4 of the mold body 1 to a lower end 5. The mold body 1 is slightly curved in a longitudinal direction L. The pouring direction G for the liquid metal runs from the upper end 4 toward the lower end 5. The outside of the mold body 1 is cooled by cooling water. The flow direction S of the cooling water is opposite to the pouring direction G.

[0038] The mold body 1 is made of copper. It has an outer surface 6 that is essentially smooth, except for a cooling structure 7 located on each of the illustrated sides 8, 9 of the outer surface 6. The two cooling structures 7 shown on sides 8, 9 are identical. The same cooling structures 7 are located on the sides not shown. The cooling structure 7 has a length L1 measured in the longitudinal direction L, which corresponds to approximately one-third of the length L2 of the mold tube 1. The cooling structure 7 begins at a distance A1 of approximately 50 mm from the upper end 4.

[0039] Figure 3 shows a side view of the detailed structure of the cooling structure 7. The cooling structure 7 consists of several V-shaped regions 10 which are arranged one behind the other in the longitudinal direction L. Each V-shaped region 10 has two legs 11, 12 of equal length and a rounded tip 13 which connects the two legs 11, 12 to one another. The tip 13 is directed towards the lower end 5, i.e. opposite to the flow direction S. In the lower region of the cooling structure 7, the cooling structure 7 is therefore V-shaped. At the upper end of the cooling structure 7, the cooling structure 7 terminates across its upper width essentially parallel to and at a distance from the upper end 4. The length of the legs 11, 12 of the upper V-shaped regions 10 decreases gradually towards the middle of the side 8, so that the middle V-shaped region 10 is considerably smaller and narrower than the V-shaped regions 10 adjoining it downwards, i.e. in the casting direction.

[0040] The V-shaped regions 10 extend on this side 8 of the outer side 6 over approximately 80% of the outside width of side 8 of the mold body 1, measured on the outside. The mold body 1 has rounded corners / edges on the outside between adjacent sides 8, 9, which are not provided with a cooling structure 7 in the sense of the invention. The cooling structure 7 ends at a parallel distance from the rounded edges of the mold body 1.

[0041] In this exemplary embodiment, 10 to 20, specifically 17, V-shaped regions 7 are arranged one behind the other in the longitudinal direction L. All V-shaped regions 10 have the same opening angle W1, which in the case of mold tubes of the design according to the invention can be between 30 and 150°. In this exemplary embodiment, it is 90°. Due to the parallel arrangement and the identical opening angles W1, all legs 12 arranged on one side of the tip 13 and legs 11 arranged on the other side are parallel to one another. The legs 11, 12 and the V-shaped regions 10 are each designed as a groove 14 in the outer surface 6. Each of the grooves 14 has the same groove width B1 and groove depth T1. Figure 5 shows the groove 14 in cross section. It has a groove width B1 of 4.6 mm and a groove depth T1 of 1.5 mm. The groove base is rounded with a radius of 2.5 mm.

[0042] Figure 6 shows an embodiment with a rectangular groove. Here, the groove width B1 is constant, as is the groove depth T1.

[0043] The embodiment shown in Figure 7 differs from that shown in Figure 6 in that, with a constant groove width B1, the groove depth T1 on one side 15 of the groove 14 has a greater depth T1 than on the opposite side 16 with the groove depth T2. The cross-section is therefore trapezoidal. The lower side 15 in the image plane is the one to which the coolant flows first.

[0044] The groove width B1 ranges from 2 to 10 mm, while the groove depth ranges from 0.1 to 2 mm. In the embodiments shown in Figures 5 and 6, the groove depth refers to the deepest part of the groove. In the embodiment shown in Figure 7, the smaller groove depth T2 is at least 0.1 mm. The groove depth T2 on the other side 15 is greater.

[0045] The distance A2 between two parallel legs 11, 12 is equal to the groove width B1. The distance A2 is measured perpendicular to the longitudinal extension of the legs 11, 12.

[0046] In the embodiment of Figures 1 and 2, the arrangement of the cooling structure 7 with respect to the respective side 8, 9 is mirror-symmetrical to the central longitudinal axis of the respective side 8, 9. The cooling structure 7 has the same distance to the left and right edge of the side 8, 9, and the legs 11, 12 are always the same length, so that the tips 13 are always located in the central longitudinal axis on the respective side 8, 9.

[0047] Figures 2 and 4 show an alternative embodiment in which the mold body 1, i.e. the mold tube, has the same basic shape, length and design. In this respect, reference is made to the explanations regarding the embodiment of Figures 1 and 3. The only difference is the differently designed cooling structure 7a, which has a plurality of V-shaped regions 10a-c arranged next to one another transversely to the longitudinal direction. Each of the V-shaped regions 10a-c has a tip 13a-c and legs 11ac, 12a-c. Adjacent legs 11ab, 12b-c are connected to one another by bends 17, so that a wave structure is created. Since all legs 11ac, 12a-c are the same length, a uniform wave structure is produced. The bends 17 and the tips 13a-c are identical.

[0048] In this exemplary embodiment, the cooling structure 7a has the same width as the cooling structure 7 in the first exemplary embodiment. The cooling structure 7a begins at the same distance A1 from the upper end 4 of the mold tube 1. The lower end of the cooling structure 7a is somewhat corrugated due to the triple and significantly smaller V-shaped regions 10a-c, but not entirely V-shaped, as in the exemplary embodiment of Figure 1. However, the cooling structure 7a also extends in this case over approximately one-third of the length L of the mold body 1. With regard to the structure of the V-shaped regions 10a-c, reference is made to the explanations for Figures 5 to 7, which show possible cross-sections of the grooves 14.

[0049] Regarding the opening angle W1 and the spacing A2 of the longitudinally successive V-shaped regions 10a-c, reference is made to the explanations for the first exemplary embodiment. The design of Figures 2 and 4 therefore shows not only V-shaped regions 10a arranged side by side transversely to the longitudinal direction L, but also arranged one behind the other in the longitudinal direction L. This exemplary embodiment comprises fourteen V-shaped regions arranged one behind the other in the longitudinal direction, and three V-shaped regions 10a-c arranged next to each other.

[0050] As in the embodiment of Figures 1 and 2, the cooling structure 7a is flowed against from below, ie opposite to the casting direction G.

[0051] Figure 8 shows an embodiment with an additional elevation 18 on the outer surface 6, wherein the elevation 18 is positioned upstream of the groove 14 in the flow direction S. The elevation 18 has a height H1 of 0.1 - 1 mm. It has a semicircular cross-section and borders directly, i.e., without a gap, the groove 14. It serves to generate turbulence.

[0052] Figures 9 and 10 show a mold plate in two different views as a further example of a mold body 1 with the aforementioned cooling structure 7. The cooling structure is arranged at a distance from the upper end 4 and the lower end 5 and is located on the outer surface 6 at the height of the meniscus. The cooling structure 7 extends only over part of the length of the mold plate, but almost over the entire width of the mold plate. The flow direction S of the coolant points from the lower end 5 to the upper end 4 of the mold body 1. A total of 6 identical V-shaped regions are arranged next to one another in the transverse direction and 7 V-shaped regions are arranged one behind the other in the longitudinal direction. The adjacent regions are connected to one another, creating a zigzag structure on the outer surface 6.

[0053] Reference symbol:

[0054] 1 - Mould body

[0055] 2 - Mold cavity

[0056] 3 - Wall of 1

[0057] 4 - upper end of 1

[0058] 5 - lower end of 1

[0059] 6 - Outer surface of 1

[0060] 7 - Cooling structure at 6 7a cooling structure

[0061] 8 - Page of 6

[0062] 9 - Page of 6

[0063] 10 - V-shaped area 10a V-shaped area 10b V-shaped area 10c V-shaped area 11 - Leg of 10 11a Leg of 10 11b Leg of 10 11c Leg of 10

[0064] 12 - Leg of 10 12a Leg of 10 12b Leg of 10 12c Leg of 10

[0065] 13 - Top of 10

[0066] 13a - top of 10 13b - top of 10 13c - top of 10

[0067] 14 - Groove

[0068] 15 - Page of 14

[0069] 16 - Page of 14

[0070] 17 - Arch

[0071] 18 - Elevation A1 - Distance from 7, 7a and 4

[0072] L - longitudinal direction

[0073] L1- Length of 7, 7a

[0074] L2 - Length of 1

[0075] G - Pouring direction

[0076] S - flow direction

[0077] A2 - Distance between 10 and 10

[0078] B1 - width of 14

[0079] H1 - Height of 18

[0080] T1 - depth of 14

[0081] T2 - depth of 14

[0082] W1 - Opening angle

Claims

Patent claims 1. Mould body (1) for the continuous casting of metal, with a longitudinal direction (L) between an upper end (4) and a lower end (5) in the casting direction, wherein at least a partial area of ​​the outer surface (6) of the mould body (1) is provided with a cooling structure (7, 7a) to improve cooling, wherein the cooling structure (7, 7a) has at least one V-shaped area (10, 10a-c) with two legs (11, 11a-c, 12, 12a-c) arranged at an opening angle (W1) to one another and a tip (13, 13a-c), wherein the tip (13, 13a-c) is directed towards the lower end (5), characterized in that the V-shaped area (10, 10a-c) is designed as a groove (14) in the outer surface (6) and has a groove width (B1) and groove depth (T1, T2).

2. Mould body (1) according to claim 1, characterized in that several V-shaped regions (10, 10a-c) are arranged one behind the other in the longitudinal direction (L) and / or next to one another transversely to the longitudinal direction (L).

3. Mould body (1) according to claim 2, characterized in that V-shaped regions (10a-c) arranged next to one another are connected to one another and form a wave structure.

4. Mould body (1) according to one of claims 1 to 3, characterized in that the number of V-shaped regions (10a-c) arranged next to one another transversely to the longitudinal direction (L) is 1 to 50, in particular 1 to 10.

5. Mould body (1) according to one of claims 1 to 4, characterized in that the opening angle (W1) of the V-shaped regions is in a range of 30° to 150°.

6. Mould body (1) according to one of claims 1 to 5, characterized in that the tips (13, 13a-c) are rounded.

7. Mould body (1) according to one of claims 1 to 6, characterized in that the legs (11, 11 ac, 12, 12a-c) of two V-shaped regions (10, 10a-c) arranged one behind the other in the longitudinal direction (L) run parallel to one another.

8. Mould body (1) according to one of claims 1 to 7, characterized in that the groove width (B1) is in a range of 2 to 10 mm and the groove depth (T1, T2) is in a range of 0.1 to 2 mm.

9. Mould body (1) according to one of claims 1 to 8, characterized in that the groove depth (T1) on a side (15) of the groove (14) against which coolant flows is greater than on the other side (16) of the groove (14).

10. Mould body (1) according to one of claims 1 to 9, characterized in that a distance (A2) between parallel legs (11, 11ac, 12, 12a-c) of adjacent V-shaped regions (10, 10a-c) corresponds at least to the groove width (B1).

11. Mould body (1) according to one of claims 1 to 10, characterized in that it has a length (L2) from the upper end (4) to the lower end (5), wherein the cooling structure (7, 7a) extends over a maximum of 30% of the length (L2).

12. Mould body (1) according to one of claims 1 to 11, characterized in that the cooling structure (7, 7a) begins at a distance (A1) of less than 50 mm from the upper end (4).

13. Mould body (1) according to one of claims 1 to 12, characterized in that the mould body (1) is a mould tube, wherein the outer surface (6) has a plurality of sides (8, 9), wherein cooling structures (7, 7a) are arranged on a plurality of sides (8, 9) and wherein the sides (8, 9) have different cooling structures (7, 7a).

14. Mould body (1) according to claim 13, characterized in that the cooling structures (7, 7a) have different opening angles (W1).

15. Mould body (1) according to one of claims 1 to 13, characterized in that the mould body (1) is a mould plate.

16. Mould body (1) according to one of claims 1 to 15, characterized in that in the flow direction (S) in front of and optionally additionally behind a groove (14) an elevation (18) is formed on the outer surface (6).

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