Process for producing a moulding using a water-soluble casting mould and material system for the production thereof

Patent metadata

Field	Value
Publication number	US-10343301-B2
Application number	US-201414768533-A
Country	US
Kind code	B2
Filing date	Feb 18, 2014
Priority date	Feb 28, 2013
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A method for producing molded parts (16), a water-soluble casting mold (6) being produced in a first step using a layering method, in particular using a powder bed-based layering method. In a second step, the surface of the casting mold (6) is sealed with the aid of a material (9; 10). A casting of the molded part (16) is then formed by filling the casting mold (6) with a free-flowing, hardenable material (13), in particular a hydraulically setting material. After the casting has solidified, the casting mold (6) is dissolved with the aid of an aqueous solution (18), in particular a heated aqueous solution (18). The present application furthermore relates to a material system for producing a water-soluble casting mold (6), comprising at least one water-soluble material for building a casting mold (6) in a layering method, as well as comprising at least one material (9; 10) for sealing the surface of the casting mold (6).

First claim

What is claimed is:

1. A method for producing a molded part, comprising the following steps:
a) producing a water-soluble casting mold using a layering method, wherein the layering method is a powder bed-based layering method where particulate material is applied in thin layers and selectively printed upon with a computer-controlled print head;
b) sealing the surface of the casting mold with a sealing material including at least one water insoluble material;
c) generating a casting of the molded part by filling the casting mold with a free-flowing, hardenable material; and
d) dissolving the casting mold with the aid of an aqueous solution, characterized in that the casting mold is produced in a 3D printing method;
wherein the particulate material includes a sand, a gypsum, a metal, or a ceramic powder:
the sealing material penetrates pores between individual particles of the casting mold;
a material of the casting mold in the layering method includes a binder;
the hardenable material is capable of a binding action with the binder or the partiuclate material, and
the sealing material prevents the binding action.

2. The method according to claim 1 , characterized in that the surface of the casting mold is sealed by immersion in a bath, by being sprayed and/or by being brushed with the sealing material.

3. The method according to claim 1 , characterized in that an underpressure above an ambient pressure or an overpressure below the ambient pressure is applied to the casting mold when it is filled with the free-flowing, hardenable material, and/or the casting mold is subjected to a shaking motion or a temperature increase.

4. The method according to claim 1 , characterized in that the casting mold is dissolved by immersion in a bath containing the heated aqueous solution.

5. The method of claim 4 , wherein the dissolution is accelerated by:
movements of the casting mold within the bath; or
the application of ultrasound.

6. The method according to claim 1 , characterized in that the hardenable material includes a casting polyamide.

7. The method of claim 1 , wherein the free-flowing, hardenable material is a hydraulically setting material.

8. The method of claim 1 , wherein the aqueous solution is a heated aqueous solution.

9. The method of claim 7 , wherein the water-soluble casting mold includes at least one water-soluble binder.

10. The method of claim 9 , wherein the at least one water-soluble binder includes at least one inorganic compound.

11. The method of claim 10 , wherein the at least one water-soluble binder includes at least one polysaccharide, at least one salt and/or at least one water-soluble polymer, or a mixture thereof.

12. The method of claim 9 , wherein the sealing material includes a water-insoluble material including a wax or a water-insoluble polymer.

13. The method of claim 12 , wherein
the surface of the casting mold is sealed by immersion in a bath, by being sprayed and/or by being brushed with the sealing material;
an underpressure above an ambient pressure or an overpressure below the ambient pressure is applied to the casting mold when it is filled with the free-flowing, hardenable material, and/or
the casting mold is subjected to a shaking motion or a temperature increase; and
the casting mold is dissolved by immersion in a bath containing the aqueous solution, the dissolution being accelerated by movements of the casting mold within the bath or by a temperature increase and/or by the application of ultrasound.

14. The method of claim 1 , wherein the water-soluble casting mold is produced from a material system including
a) at least one water-soluble material for building a casting mold in a layering method, which comprises at least one particulate material as well as at least one water-soluble binder; and
b) the sealing material for sealing the surface of the casting mold.

15. The method of claim 14 , wherein the sealing material for sealing the surface of the casting mold includes a wax, at least one fatty acid, at least one water-insoluble polymer, stearyl alcohol and/or cetyl alcohol, or a mixture thereof.

16. The method of claim 15 , wherein
the surface of the casting mold is sealed by immersion in a bath, by being sprayed and/or by being brushed with the sealing material;
an underpressure above an ambient pressure or an overpressure below the ambient pressure is applied to the casting mold when it is filled with the free-flowing, hardenable material, and/or
the casting mold is subjected to a shaking motion or a temperature increase; and
the casting mold is dissolved by immersion in a bath containing the aqueous solution, the dissolution being accelerated by movements of the casting mold within the bath or by a temperature increase and/or by the application of ultrasound.

17. The method of claim 1 , wherein the dissolving of the casting mold is after the casting has solidified and the aqueous solution is temperature controlled.

18. The method of claim 1 , wherein the binding action includes a chemical reaction of the hardenable material with the binder or the partiuclate material, and wherein the sealing material prevents the chemical reaction.

19. The method of claim 1 , wherein the method includes a step of washing the water-insoluble material off of the molded part.

20. The method of claim 1 , wherein the hardenable material includes a free-flowing material that transitions to a hardened state by a polymerization reaction.

21. The method of claim 1 , wherein the casting mold has a rough surface and the sealing material smooths the surface.

22. The method of claim 1 , wherein the casting mold is cleaned and a surface is mechanically processed before the step of sealing.

23. The method of claim 1 , wherein the sealing material includes a wax, a fatty acid, a water-insoluble polymer, a stearyl alcohol, or a cetyl alcohol.

24. The method of claim 1 , wherein the binding action includes hardening by forming a crystalline structure.

25. A method of for producing a molded part, comprising the following steps:
a. producing a water-soluble casting mold using a layering method, wherein the layering method is a powder bed-based layering method where particulate material is applied in thin layers and selectively printed upon with a computer-controlled print head;
b. sealing the surface of the casting mold with a sealing material including a water insoluble material including at least one water insoluble material;
c. generating a casting of the molded part by filling the casting mold with a free-flowing, hardenable material; and
d. dissolving the casting mold with the aid of a heated aqueous solution, wherein the casting mold is produced in a 3D printing method;
the sealing material penetrates pores between individual particles of the casting mold;
a material of the casting mold in the layering method includes a binder;
the hardenable material is capable of a binding action with the binder or the partiuclate material, and
the sealing material prevents the binding action.

26. The method of claim 25 , wherein
the surface of the casting mold is sealed by immersion in a bath, by being sprayed and/or by being brushed with the sealing material;
an underpressure above an ambient pressure or an overpressure below the ambient pressure is applied to the casting mold when it is filled with the free-flowing, hardenable material, and/or
the casti

Assignees

• Voxeljet Ag
• FluidSolids AG

Inventors

• Günther Daniel
• Gnüchtel Ingo
• Karrer Beat

Classifications

• B29C33/56

  Coatings {, e.g. enameled or galvanised}; Releasing, lubricating or separating agents {(in-mould coating B29C37/0028; using or applying separating agents B29C37/0067)} · CPC title

• B28B7/36

  Linings or coatings, {e.g. removable, absorbent linings, permanent anti-stick coatings; Linings becoming a non-permanent layer of the moulded article}(lubricating surfaces of moulds, cores or mandrels B28B7/38) · CPC title

• B29C64/10

  Processes of additive manufacturing · CPC title

• B29C64/165

  using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber · CPC title

• B29C33/52

  soluble or fusible {(in particular used in injection moulding B29C45/4457)} · CPC title