3D multi-stage method

• US 10,052,682 B2
• Filed: 10/10/2013
• Issued: 08/21/2018
• Est. Priority Date: 10/12/2012
• Status: Active Grant

• Current Assignee: Voxeljet AG
• Original Assignee: Voxeljet AG
• Inventors: Ederer, Ingo, Gunther, Daniel
• Primary Examiner(s): Tentoni, Leo B
• Application Number:
  US14/435,269
• Publication Number:
  US 20150273572A1
• Time in Patent Office: 1,776 Days
• Field of Search: 264113, 264236, 264347
• CPC Class Codes: B22C 1/18 of inorganic agents B22C1/162 takes precedence
• CPC Class Codes: B22C 1/22 of resins or rosins
• 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: B29C 64/171 specially adapted for manufacturing multiple 3D objects
• CPC Class Codes: B33Y 70/10 Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• CPC Class Codes: C04B 41/4584 Coating or impregnating of particulate or fibrous ceramic material C04B20/10, C04B35/628 take precedence
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

The present invention relates to a multi-stage method for producing one or multiple molded bodies, the method comprising the following steps: a) constructing one or multiple molded bodies in layers by repeatedly applying particulate material by the 3D printing method; b. a presolidification step for achieving a presolidification of the molded body; c. an unpacking step, wherein the unsolidified particulate material is separated from the presolidified molded body; d. a final solidification step, in which the molded body receives its final strength due to the action of thermal energy. The invention also relates to a device which may be used for this method.

Claims

1. A method for producing one or multiple molded bodies, wherein the method comprises the following steps:

a. constructing one or multiple molded bodies in layers by repeatedly applying particulate material including a casing or coating and selectively printing a fluid including a solvent on the particulate material, wherein the casing or coating includes a soluble polymer;

b. a pre-solidification step for achieving a pre-solidification of the molded body, wherein the pre-solidification step includes forming a bridge between two adjacent particles of the particulate material by liquefying the soluble polymer with the solvent and then solidifying by removing the solvent from the bridge;

c. an unpacking step, wherein the unsolidified particulate material is separated from the pre-solidified molded body; and

d. a final solidification step, after the unpacking step, in which the pre-solidified molded body receives its final strength due to the action of thermal energy;

wherein the action of thermal energy includes a chemical mechanism.

2. The method according to claim 1, wherein the final solidification step includes heating to a temperature from 110°

C. to 200°

C.

3. The method according to claim 2, wherein the the casing or coating includes a binder.

4. The method according to claim 2, wherein the casing or coating comprises or includes thermoplastic polymers, soluble polymers, waxes, synthetic and natural resins, sugars, salts, inorganic network formers or water glasses.

5. The method according to claim 1, wherein the pre-solidification step takes place using a solvent comprising water, hydrocarbons, alcohols, esters, ethers, ketones, aldehydes, acetates, succinates, monomers, formaldehyde, phenol and mixtures thereof.

6. The method according to claim 3, wherein the binder contains polymerizable monomers.

7. The method according to claim 2, wherein the pre-solidified molded body has a flexural strength of more than 120 N/cm² and the molded body has a flexural strength of more than 250 N/cm² after the final solidification step;

wherein the material contained in the casing or coating contributes to the final strength or to the preliminary strength in the pre-solidification step and to the final strength in the final solidification step.

8. The method of claim 1, wherein the molded body is subjected to one or multiple additional processing steps;

the molded body is solidified in the pre-solidification step to the extent that an unpacking from the unsolidified particulate material is possible, and the molded body essentially retains its shape defined in the 3D printing method;

the unpacking takes place manually or mechanically or in a robot-assisted manner;

the pre-solidified molded body (green body) has a flexural strength of more than 120 N/cm² following the pre-solidification step;

the molded body has a flexural strength of more than 250 N/cm² after the final solidification step;

the pre-solidification step takes place without the introduction of additional thermal energy;

the pre-solidification step takes place using a solvent and/or a polymerization reaction;

the final solidification step takes place with the aid of heat treatment; and

the body is heat-treated with the assistance of an inert material.

9. The method of claim 8, wherein the presolidified molded body (green body) has a flexural strength of 120 to 400 N/cm² following the presolidification step;

and the molded body has a flexural strength of more than 750 N/cm² after the final solidification step.

10. The method of claim 1, wherein a temperature in the final solidification step is from 130°

C. to 200°

C.

11. The method of claim 2, wherein the temperature at the component is maintained within a time range of 2 to 24 hours.

12. The method of claim 11, wherein natural silica sand, kerphalite, cera beads, zircon sand, chromite sand, olivine sand, chamotte, corundum or glass spheres are used as the particulate material.

13. The method of claim 6, wherein the coating or casing contains materials for starting a polymerization with the binder.

14. The method of claim 8, wherein the casing or coating includes one or multiple materials;

the casing or coating includes a binder;

the casing or coating comprises or includes thermoplastic polymers, soluble polymers, waxes, synthetic and natural resins, sugars, salts, inorganic network formers or water glasses;

the pre-solidification step takes place using a solvent comprising water, hydrocarbons, alcohols, esters, ethers, ketones, aldehydes, acetates, succinates, monomers, formaldehyde, phenol and mixtures thereof;

the casing or coating contains materials for starting a polymerization with the binder;

the pre-solidified molded body has a flexural strength of more than 120 N/cm² and the molded body has a flexural strength of more than 250 N/cm² after the final solidification step;

the material contained in the casing or coating contributes to the final strength or to the preliminary strength in the pre-solidification step and to the final strength in the final solidification step; and

two different materials are contained in the casing or coating, the one material being essentially destined for the pre-solidification step and the other material essentially being destined for the final solidification step.

15. The method of claim 1, wherein only the fluid including the solvent is printed on the particulate material.

16. A method for producing one or multiple molded bodies, wherein the method comprises the following steps:

a. constructing one or multiple molded bodies in layers by repeatedly applying particulate material by the 3D printing method;

b. a pre-solidification step for achieving a pre-solidification of the molded body;

c. an unpacking step, wherein the unsolidified particulate material is separated from the pre-solidified molded body; and

d. a final solidification step, in which the pre-solidified molded body receives its final strength due to the action of thermal energy;

wherein the particulate material includes a base material and a coating or casing; and

the coating or casing contains a color indicator which is activated by a binder.

17. The method of claim 16, wherein the molded body is subjected to polishing, dyeing, or both.

18. A method for producing one or multiple molded bodies, wherein the method comprises the following steps:

a. constructing one or multiple molded bodies in layers by repeatedly applying particulate material by the 3D printing method;

b. a pre-solidification step for achieving a pre-solidification of the molded body;

c. an unpacking step, wherein the unsolidified particulate material is separated from the pre-solidified molded body;

d. a step of repacking the pre-solidified molded body in an inert material; and

e. a final solidification step, after the repacking step, in which the pre-solidified molded body receives its final strength due to the action of thermal energy while supported by the inert material;

wherein the particulate material includes a base material and a coating or casing having one or multiple materials for the pre-solidification step and for the final solidification step.

19. The method of claim 18, wherein two different materials are contained in the casing or coating, the one material being essentially destined for the pre-solidification step and the other material essentially being destined for the final solidification step.

20. The method according to claim 19, wherein the final solidification step includes a chemical reaction.