CASTING MOLD HAVING AT LEAST ONE CAVITY FOR MANUFACTURING AT LEAST ONE CAST ARTICLE

Abstract

A casting mold having at least one cavity for manufacturing at least one cast article, in which at least some areas of a casting surface of the casting mold delimiting the cavity have a surface texture. The surface texture has multiple elementary cells, wherein each elementary cell has a structure that projects and/or is recessed with respect to the casting surface and ends within the applicable elementary cell. In addition, a cast article produced by the casting mold is provided.

Claims

1. A casting mold comprising: at least one cavity for manufacturing at least one cast article; a surface texture formed on at least a portion of a casting surface of the casting mold delimiting the cavity, the surface texture having a plurality of elementary cells; and air cushions formed between a metal melt and the casting mold; wherein each of the plurality of elementary cells has a structure that projects and/or is recessed with respect to the casting surface and ends within the applicable elementary cell, wherein the casting mold is a permanent mold, wherein the elementary cells of the surface texture form a pattern with substantially identically designed structures, wherein all of the plurality of elementary cells of the surface texture have substantially the same size and/or shape, and wherein the surface texture is formed by a laser on the portion of the casting surface.

2. The casting mold according to claim 1, wherein two or more elementary cells of the surface texture overlap at least partially.

3. The casting mold according to claim 1, wherein the structure is spherical.

4. The casting mold according to claim 1, wherein the structure has at least one bump or recess that extends in a flow direction of the metal melt in the cavity.

5. The casting mold according to claim 4, wherein the at least one bump or recess have different widths or different heights or depths.

6. The casting mold according to claim 1, wherein the structure has two or more bumps or recesses that are not connected to one another or that form a connected structure.

7. The casting mold according to claim 4, wherein the bumps or recesses of the structure are arranged to be parallel to one another.

8. The casting mold according to claim 1, wherein the structure has two or more connected bumps or recesses that together enclose an acute angle.

9. The casting mold according to claim 8, wherein the at least two or more bumps or recesses of the structure have different lengths or different widths or different heights or different depths.

10. The casting mold according to claim 1, wherein the structure is a bionic structure.

11. A casting mold comprising: a surface texture that includes a plurality of elementary cells; and at least one cavity for manufacturing at least one cast article in which at least some areas of a casting surface of the casting mold delimiting the cavity have the surface texture, wherein each elementary cell has a structure that projects or is recessed with respect to the casting surface, wherein the structures of the elementary cells that are adjacent to one another are connected in design and form a pattern of orthogonal bumps or recesses, wherein a ratio between the casting surface and a projecting or recessed structure surface within an elementary cell is less than 2:1, wherein air cushions are formed between a metal melt and the casting mold, and wherein the surface texture is produced by a material removal process via a laser on the at least some areas of the casting surface.

12. The casting mold according to claim 11, wherein the structure has bumps or recesses, wherein a height or depth of the bumps or recesses corresponds to half a distance between two parallel bumps or parallel recesses in adjacent elementary cells.

13. The casting mold according to claim 11, wherein the bumps or recesses have a semicircular or V-shaped cross-section.

14. The casting mold according to claim 11, wherein the orthogonal bumps or recesses of the pattern of the surface texture have a constant height or depth.

15. The casting mold according to claim 11, wherein the surface texture is produced by a machining process.

16. The casting mold according to claim 11, wherein at least two surface textures that have the same pattern or different patterns are arranged on the casting surface of the casting mold.

17. The casting mold according to claim 11, wherein the casting mold is a permanent mold.

18. A cast article produced in a casting mold according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0029] FIG. 1 illustrates a cast article according to the invention in a perspective view;

[0030] FIG. 2 is a schematic diagram of a casting mold according to the invention;

[0031] FIG. 3 illustrates a surface texture in the casting surface of the casting mold in a view corresponding to A-A in FIG. 2;

[0032] FIGS. 4a to 4e illustrate various arrangements of elementary cells to form a surface texture;

[0033] FIGS. 5a to 5f illustrate an embodiment of a surface texture;

[0034] FIGS. 6a to 6f illustrate an embodiment of a surface texture;

[0035] FIGS. 7a to 7f illustrate an embodiment of a surface texture;

[0036] FIGS. 8a to 8f illustrate an embodiment of a surface texture;

[0037] FIGS. 9a to 9f illustrate an of a surface texture;

[0038] FIG. 10 illustrates an embodiment of a surface texture; and

[0039] FIGS. 11a to 11f illustrate an embodiment of the surface texture.

DETAILED DESCRIPTION

[0040] A casting mold 2 shown in FIG. 2 in a schematic diagram is provided for the purpose of producing a cast article 1, shown in FIG. 1 and implemented as a chassis part, from aluminum or an aluminum alloy by means of a casting process.

[0041] The casting mold 2, implemented as a permanent mold, has a cavity 4 that is delimited by casting surfaces 3 and into which a liquid or fluid metal melt 5 of aluminum is poured during the course of the casting process, which melt then moves continuously in a flow direction 6 in the cavity 4. At least some areas of the substantially smooth casting surfaces 3 have a surface texture 7. FIG. 2 shows the point in time of the casting process when a melt front 8 of the metal melt 5 has not yet reached the region where the surface texture 7 is arranged.

[0042] FIG. 3 shows the surface texture 7 represented in FIG. 2 in a view corresponding to line A-A in FIG. 2. The surface texture 7 has a plurality of elementary cells 9 arranged next to or beneath one another and forming a pattern, which cells are, in particular, square in design. FIGS. 4a) to e) show examples of a possible arrangement of the elementary cells 9 within the surface texture 7. To form the surface texture 7, the elementary cell 9 is repeated by inversion, displacement, rotation, or mirror-imaging. During the process, the elementary cells 9 can also at least partially overlap one another. Preferably, all elementary cells 9 forming a surface texture 7 are identical in design. It is also possible, however, for a surface texture 7 to has a combination of different elementary cells 9, 9′ that differ with regard to size and/or shape. The edge length of the elementary cells 9 is preferably less than 10 mm.

[0043] According to the invention, provision is made that each elementary cell 9 has a structure 10 that projects and/or is recessed with respect to a base level of the casting surface 3 and ends within the applicable elementary cell 9. FIGS. 5 to 10 show different embodiments of the surface textures 7 in different views a) to f). The views 5a) to 10a) show a section of the applicable surface texture 7 in the casting surface 3 of the casting mold 2 in a perspective representation. A top view of the surface texture 7 shown in the views 5a) to 10a) and an orientation of the structures 10 relative to the flow direction 6 of the metal melt 5 are represented in the views 5b) to 10b).

[0044] The views 5c) to 10c) each show an individual elementary cell 9 spanned by the x-axis and the y-axis with the applicable structure 10. An orientation of the structure 10 within the elementary cell 9 and relative to the flow direction 6 of the metal melt 5 is represented by the two principal directions a and b. A cross-sectional view along the line A-A in the views 5c) to 10c) is illustrated in views 5d) to 10d). Views 5e) to 10e) show the technically simplified structures 10 from views 5c) to 10c), and the views 5f) to 10f) show the applicable cross-sectional representation along the line A-A in the views 5e) to 10e).

[0045] The surface textures 7 shown in FIGS. 5 and 6 each have, within an elementary cell 9, a structure 10 that is raised with respect to the base level of the casting surface 3, has multiple bumps 11, and is similar in design to a scale of a shark's skin. Generally speaking, this structure 10 within the elementary cell 9 can also be designed as the inverse, and has multiple recesses set back with respect to the base level of the casting surface 3. The illustrated structure 10 within each elementary cell 9 has a total of five tapered bumps 11 arranged next to one another that extend in the principal direction b within the elementary cell 9. As can be seen in views 6c) and 6d, the bumps 11 have different lengths 12, widths 13, and heights 14. In the embodiment from FIG. 5, the principal direction b of the structure 10 is parallel to the y-axis, and in the embodiment from FIG. 6, the structure 10 is oriented at an angle of 45° to the y-axis. The elementary cells 9 of the two embodiments are arranged such that the principal direction b of the structures 10 within the elementary cells 9 extends in the direction of flow 6 of the metal melt 5, as is evident from the views 5b) and 6b). In the embodiment from FIG. 6, this results in a smaller distance between the individual structures 10 of the applicable adjacent elementary cells 9 as compared to the embodiment in FIG. 5, and consequently a higher packing density within the overall surface texture 7.

[0046] Another embodiment of the surface texture 7 is shown in FIG. 7. The elementary cells 9 of this surface texture 7 each have a structure 10 that is raised with respect to the base level of the casting surface 3, has multiple connected bumps 11, and is similar in design to a crow's foot. The structure 10 has a central bump 11 oriented in the principal direction b, and two bumps 11′ that are angled at an acute angle α therefrom. The bumps 11, 11′ have different lengths 12, widths 13, and heights 14. The elementary cells 9 can be arranged next to and beneath one another at the same height, or as shown in view 7b), can be offset from one another in the direction of flow 6 of the metal melt 5. This ensures a higher packing density of the structures 10 within the surface texture 7.

[0047] Another embodiment of a structure 10 oriented in the direction of flow 6 is shown in FIG. 8. Here, the structure 10 has multiple impressions of a bamboo stalk 15 oriented in the flow direction 6, arranged next to one another and partially overlapping. The joints 16 of the bamboo stalk 15 are arranged offset from one another in the flow direction 6. This results in an undulating, sinusoidal shape of the structure 10 (view 8e)).

[0048] The structures 10 described in FIGS. 5 through 8 are directional, so-called unidirectional, structures 10 which preferably are employed in regions with rapid, strongly directed flow of the metal melt 5. The applicable structure 10 in this case is oriented substantially in the direction of flow 6 of the metal melt 5.

[0049] Another embodiment of the surface texture 7 is shown in FIG. 9. Here, the structure 10 within the elementary cell 9 is designed as a spherical, in particular hemispherical, bump 11. Because of the symmetry of the bump 11, this structure 10 is called a non-directional structure 10, which can be arranged or oriented independently of the expected flow direction 6 of the metal melt 5. A surface texture 7 with such non-directional structures 10 is employed in particular in regions of the cavity 4 through which flow passes slowly with a flow direction 6 that tends to be undefined or in the case of changes in flow direction during mold filling.

[0050] In FIG. 10, another embodiment of the surface texture 7 is shown that likewise has non-directional structures 10. The structures 10 are likewise spherical or hemispherical in design, and can be implemented as a bump or a recess. In this design, the bumps or recesses can each have different heights or depths. Also, more than one hemispherical structure can be present within one elementary cell 9. The structures 10 form a stochastically and/or geometrically definable structured surface.

[0051] Another embodiment of a surface texture 7 with a non-directional structure 10 is shown in FIG. 11. The surface texture 7 likewise has multiple elementary cells 9, wherein each elementary cell 9 has a structure 10 that projects with respect to the casting surface 3. The structures 10 of applicable adjacent elementary cells 9 are connected in design, and form a pattern of orthogonal bumps 11 that enclose an angle γ of 90° (view 10e)). Here, a ratio between the casting surface 3 and the projecting structure surface within an elementary cell 9 is less than 2:1. As can be seen in views 10d) and 10f), the bumps 11 have a semicircular cross-section. A height 14 of the bumps 11 corresponds approximately to half the distance between two parallel bumps 11 in adjacent elementary cells 9. The orthogonally arranged bumps 11 of the pattern of the surface texture 7 have a constant height 14.

[0052] As can be seen in FIG. 1, the cast article 1 produced in the casting mold 2 according to the invention has a negative shape 17 of the surface texture 7 of the casting mold 2. Depending on the geometry of the cast article and the prevailing flow directions 6 and flow velocities of the metal melt 5 during the casting process, the cast article 1 or the casting mold 2 can have multiple surface textures 7 that are not connected to one another.

[0053] In summary, due to the surface texture 7 according to the invention in the casting mold 2, various advantageous effects are brought about that cause the flow length of the metal melt 5 in the casting mold 2 during the casting process to be extended. In consequence, cast articles 1 with wall thicknesses less than 5 mm can be produced.

[0054] Because of the structures 10 in the elementary cells 9, a so-called air cushion effect arises due to locally generated air vortex zones, with the air cushions between the metal melt 5 and the casting mold 2 acting as an insulator for the thermal and tribological transition. In this way, the flow length and the flow velocity of the metal melt 5 can be controlled in a directed way.

[0055] Also arising because of the structure 10 is the so-called radiator effect, in which the cooling rate and the cooling direction are influenced in a specific way through local cooling effects, and which leads to a specific reduction and to a specific fracturing of the oxide film forming on the metal melt 5 during the casting process.

[0056] The flow direction 6 and the flow velocity, as well as the solidification rate of the metal melt 5, are controlled in a directed way through the design of the structure 10 and the arrangement of the elementary cells 9 within the surface texture 7. Moreover, the roughness grade of the surface of the casting mold 2 produced by the structures 10 provides for a constant fracturing of the oxide film of the metal melt 5 and thus for a lengthening of the flow path of the metal melt 5 within the cavity 4.

[0057] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.