Method for the layered construction of models

• US 8,020,604 B2
• Filed: 06/14/2004
• Issued: 09/20/2011
• Est. Priority Date: 06/17/2003
• Status: Expired due to Fees

• Current Assignee: Exone GMBH (Desktop Metal, Inc.)
• Original Assignee: Höchsmann, Rainer
• Inventors: Höchsmann, Rainer
• Primary Examiner(s): Kerns; Kevin P
• Application Number:
  US10/559,920
• Publication Number:
  US 20060237159A1
• Time in Patent Office: 2,654 Days
• Field of Search: 164/525, 164/23, 164/4.1, 164/456
• US Class Current: 164/456
• CPC Class Codes: B22C 9/02 Sand moulds or like moulds for shaped castings
• CPC Class Codes: B29C 64/165 using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A method for the layered construction of models is disclosed, whereby at least one first material is applied to a building platform and then a second material is selectively applied in layers. Both application steps are then repeated until the desired model is obtained and the both materials form a solid body with a desired mixing ratio. The first material comprises a moulding sand and the first and/or the second material comprises a binder, comprising a crystalline salt binder, or/and a protein binder.

Claims

1. A procedure for layered composition of a metal casting mould, comprising the steps of:

a) mixing solid particles of a bonding agent comprising a salt-crystal or a salt-crystal and protein combination, with a sand that comprises quartz sand, zircon sand, olivine sand, fireclay sand, or a combination thereof, to form a bonding agent/sand admixture;

b) applying a thin layer of the bonding agent/sand admixture to an assembly field of an assembly platform;

c) selectively applying an aqueous solvent via a droplet generator to a cross-sectional area of the metal casting mould being generated, in a sufficient dose so that the sand is bound by the salt-crystal or the salt-crystal and protein combination without impairing the outline and accuracy of the metal casting mould on the assembly field of the assembly platform;

d) dissolving with the aqueous solvent the salt-crystal or salt-crystal and protein combination with the aqueous solvent, so that the salt-crystal or salt-crystal and protein combination substantially encompasses the sand particles within a layer and any underlying sand particles that may be present;

e) removing through drying the aqueous solvent so that the bonding agent/sand admixture bind together;

f) lowering the assembly platform;

g) repeating at least steps (a)-(f) for applying an additional layer until the metal casting mould is complete;

h) casting a metal casting from the resulting metal casting mould;

i) coring the metal casting through immersion in a water bath after the metal casting has been cast;

j) dissolving the bonding agent/sand admixture in the water bath; and

k) recycling the sand from the water bath.

2. The procedure according to claim 1, wherein the solvent is removed by applying microwave radiation heating or warm air.

3. The procedure according to claim 1, whereby the bonding agent comprises at least magnesium sulphate or sodium polyphosphate.

4. The procedure according to claim 1, wherein the salt-crystal or the salt-crystal and protein combination comprises 3 percent by weight water before the salt-crystal or the salt-crystal and protein combination is applied to the assembly platform.

5. The procedure according to claim 1, wherein the step of removing begins after a sufficient amount of reaction time has elapsed.

6. The procedure according to claim 1, wherein the casting mould is sufficiently dried so that boiling retardation is prevented.

7. The procedure according to claim 5, wherein the casting mould is sufficiently dried so that boiling retardation is prevented.

8. A method for producing a model comprising:

a) mixing solid particles of a bonding agent comprising a salt-crystal, a protein, or both, with particles of sand the particles of sand including;

quartz sand, zircon sand, olivine sand, fireclay sand, or a combination thereof, to form a bonding agent/sand solid particle admixture;

b) applying a thin layer of the bonding agent/sand solid particle admixture to an assembly field of an assembly platform;

c) selectively applying a solvent to a cross-sectional area of the thin layer of the bonding agent/sand solid particle admixture, to underlying sand particles that may be present, to the bonding agent/sand admixture in required areas for reacting the solvent with the bonding agent/sand admixture, or a combination thereof, in a sufficient dose so that the particles of sand within the thin layer are bonded to each other by the salt crystal, the protein, or both without impairing the outline and accuracy of the metal casting mould on the assembly field of the assembly platform;

d) drying the particles of sand so that the solvent is removed;

e) lowering the assembly platform; and

f) repeating at least steps (a)-(e) for applying an additional layer until the model is complete.

9. The procedure of claim 8, further including a step of recycling the sand from the resulting mould.

10. The method of claim 8, wherein the solvent dissolves the bonding agent so that the particles of sand are coated with the bonding agent.

11. The method of claim 8, wherein the solvent essentially comprises water.

12. The method of claim 11, wherein the solvent is applied by a droplet generator.

13. The method of claim 11, wherein the solvent is applied by screen printing or spraying through a template.

14. The method of claim 8, wherein the solvent is removed by drying after an appropriate reaction time has elapsed.

15. The method of claim 8, whereby the bonding agent comprises magnesium sulphate or sodium polyphosphate.

16. The method of claim 8, whereby the model is a metal casting mould.

17. The procedure according to claim 8, wherein the step of drying begins after a sufficient amount of reaction time has elapsed.

18. The procedure according to claim 8, wherein the casting mould is sufficiently dried so that boiling retardation is prevented.

19. The procedure according to claim 17, wherein the casting mould is sufficiently dried so that boiling retardation is prevented.

20. The procedure according to claim 8, wherein the bonding agent comprises 3 percent by weight water before the bonding agent is applied to the assembly platform.