CASTING CORE FOR CASTING MOULDS, AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The present invention relates to a casting core for casting moulds, the casting core comprising an inner core and an outer core arranged around the inner core. The outer core contains or consists of ceramic particles bound with a binder. The inner core contains ceramic particles bound with a binder and additionally one or more placeholder elements. The placeholder element(s) is/are at least partially thermally decomposable. The present invention also relates to a method for producing the casting core according to the invention and to the use of the casting core according to the invention.

Claims

1. A casting core for casting moulds, comprising: a core heart; and a core sheath disposed around the core heart; wherein the core sheath includes multiple ceramic particles bonded by a binder, wherein the core heart includes multiple ceramic particles bonded by a binder and a placeholder element, and wherein the placeholder element is at least partially thermally decomposable.

2. The casting core according to claim 1, wherein at least one of the ceramic particles of the core or the ceramic particles of the core heart are at least one of: quartz sand particles, zirconium sand particles, aluminosilicate particles, mullite particles, inorganic hollow balls, aluminum oxide particles, or a mixture thereof.

3. The casting core according to claim 1, wherein at least one of the ceramic particles of the core sheath or the ceramic particles of the core heart have an average particle diameter of between 0.5 m and 500 m inclusive.

4. The casting core according to claim 1, wherein at least one of the binder of the core sheath or the binder of the core heart are at least one of: an inorganic binder or a phosphate binder, plaster, cement, an organic binder or a mixture thereof.

5. The casting core according to claim 1, wherein the placeholder element is at least partially thermally decomposable from a temperature in a range between 300 C. and 1,500 C. inclusive.

6. The casting core according to claim 1, wherein the placeholder element is combustible.

7. The casting core according to claim 1, wherein the placeholder element is at least one of: a wood foam element, a polymer foam element, polystyrene balls, polymer granulates, or mixtures thereof.

8. (canceled)

9. The casting core according to claim 1, wherein the core sheath and the core heart have multiple pores, wherein the pores have an average pore size of between 1 m and 50 m inclusive, and wherein the core sheath has a lower porosity than the core heart.

10. The casting core according to claim 1, wherein the core sheath has a thickness of between 3 mm and 15 mm, inclusive.

11. The casting core according to claim 1, wherein the core heart has a diameter of between 5 mm and 100 mm, inclusive.

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. The casting core according to claim 4, wherein the inorganic binder is at least one of a silica sols, waterglass, or another silicate binder.

17. The casting core according to claim 4, wherein the organic binder is at least one of a plastic material resin or a protein binder.

18. The casting core according to claim 5, wherein the temperature range is between 400 C. and 1,400 C., inclusive.

19. The casting core according to claim 5, wherein the temperature range is between 500 C. and 1,300 C., inclusive.

20. The casting core according to claim 6, wherein the placeholder element is combustible without residue.

21. The casting core according to claim 10, wherein the thickness is between 3 mm and 7 mm, inclusive.

22. The casting core according to claim 11, wherein the core heart has a diameter of between 15 mm and 100 mm, inclusive.

23. A method for production of a casting core, the method comprising: mixing a first aqueous ceramic suspension, the first aqueous ceramic suspension including multiple ceramic particles, a binder, water, and a placeholder element, wherein the placeholder element is at least partially thermally decomposable; pouring the first aqueous ceramic suspension into, or producing the first aqueous ceramic suspension in a first casting mould which has a negative contour of a core heart of the casting core; solidifying the first aqueous ceramic suspension to form the core heart of the casting core; removing solidified the core heart from the first casting mould; drying the core heart; inserting the dried core heart into a second casting mould which has the negative contour of the casting core; pouring a second aqueous ceramic solution into the second casting mould, wherein the second aqueous solution includes multiple ceramic particles, a binder, and water; solidifying the second aqueous ceramic suspension to form a core sheath of the casting core around the core heart to form a core heart-core sheath combination making up the casting core; removing the solidified casting core from the second casting mould; and drying the solidified casting core.

24. The method according to claim 23, wherein the placeholder element includes multiple polystyrene balls.

25. The method according to claim 23, wherein the placeholder element is at least one of a wood foam element or a polymer foam element, and wherein the placeholder element is cut to a shape of the core heart and located in the first casting mould, and wherein the first aqueous ceramic suspension is poured around the placeholder element.

26. A casting core for casting moulds, comprising: a core heart; and a core sheath; wherein the core sheath includes multiple ceramic particles bonded by a binder, wherein the core heart includes multiple ceramic particles bonded by a binder and a placeholder element, wherein at least one of the ceramic particles of the core sheath or the ceramic particles of the core heart are at least one of: quartz sand particles, zirconium sand particles, aluminosilicate particles, mullite particles, inorganic hollow balls, or a mixture thereof, wherein at least one of the binder of the or sheath or the binder of the core heart is at least one of an inorganic binder or an organic binder, wherein the placeholder element is at least partially thermally decomposable, wherein the placeholder element is combustible without residue, and the placeholder element is at least one of: a wood foam element, a polymer foam element, polystyrene balls, polymer granulates, or a mixture thereof

27. The casting core of claim 26, wherein: the placeholder element is at least partially thermally decomposable from a temperature in a range between 300 C. and 1500 C., inclusive; the core sheath and the core heart have multiple pores, wherein the pores have an average pore size of between 1 m and 50 m inclusive, and wherein the core sheath has a lower porosity than the core heart; the core sheath has a thickness of between 3 mm and 15 mm, inclusive; and the core heart has a diameter of between 5 mm and 100 mm, inclusive.

Description

EMBODIMENT 1

[0042] A core mass based on a phosphate binder is produced as follows: 60% phosphate binder Wirovest (BEGO) and 40% quartz dust are introduced in water until a flowable consistency is obtained. A reticulated foam material (Dryfeel based on polyether, pore size 15 ppi, Eurofoam) is cut into the shape of the core heart, laid in a mould and infiltrated and poured around with the produced core mass. After solidification begins, the component is removed from the mould. The core heart is dried (at 90 C. for removing excess water, subsequently at 180 C. for one hour) and laid into a dividable mould which images the geometry of the core. The core heart has the core material poured around it. After solidification and removal from the mould, the core is dried at a temperature of 180 C. for one hour.

EMBODIMENT 2

[0043] 50% by volume of polystyrene balls is stirred into a ceramic mass, consisting of 88.5% phosphate binder Wirovest (BEGO) and 11.5% demineralised water, and poured into a mould for the core heart. The solidified component is removed from the mould and placed in the dividable core mould and has the following ceramic mass poured around: 40% mullite (Symulox M72 K0, Nabaltec, average particle size between 7-15 m) and 60% phosphate binder Wirovest (BEGO) are agitated in water until a flowable mass is obtained. After solidification, the core is removed from the mould and dried at 100 C.