METHOD FOR HIGH TEMPERATURE HEAT TREATING OF METAL OBJECTS FORMED IN A METAL DROP EJECTING THREE-DIMENSIONAL (3D) OBJECT PRINTER
A metal object produced by a three-dimensional (3D) metal object manufacturing apparatus is subjected to a high temperature heat treatment to improve bonding of the object layers, especially in the vertical or Z-axis direction. A supporting structure is formed around the metal object to retain the shape and features of the object during the high temperature heat treatment. The supporting structure is formed in a manner that is sufficient to retain the shape of the metal object during the heat treatment but is easily removed once the heat treatment is finished.
1 . A method for high temperature heat treatment of a metal object produced with a melted metal drop ejecting apparatus comprising:
removing the metal object from the melted metal drop ejecting apparatus;
forming a supporting structure about the metal object;
heating the metal object to a temperature greater than a solidus temperature of a metal ejected by the melted metal drop ejecting apparatus to produce the metal object; and
removing the metal object from the supporting structure.
2 . The method of claim 1 further comprising:
maintaining the temperature of the metal object above the solidus temperature for a predetermined period of time sufficient to bond layers of the metal object in a vertical direction.
3 . The method of claim 2 , the supporting structure formation further comprising:
filling a container with a granular material after the metal object has been placed on a layer of the granular material in the container.
4 . The method of claim 3 wherein the granular material is essentially comprised of sand.
5 . The method of claim 3 wherein the granular material is essentially comprised of glass beads having a diameter in a range of about 10 μm to about 50 μm.
6 . The method of claim 3 wherein the granular material has a fusing temperature greater than the melting temperature of the metal used to produce the metal object.
7 . The method of claim 2 , the supporting structure formation further comprising:
filling a container with a suspension of a solid material after the metal object has been placed on a layer of the suspension of the solid material in the container.
8 . The method of claim 7 wherein the suspension is a mixture of water and calcined lime.
9 . The method of claim 2 , the supporting structure formation further comprising:
forming a solution by dissolving a solute in a solvent;
pouring the solution into a container in which the metal object has been placed;
evaporating the solvent from the solution in the container to encase the metal object in the solute.
10 . The method of claim 9 further comprising:
dissolving the solute to remove the metal object from the solute.
11 . The method of claim 9 further comprising:
packing grains of a salt about the metal object that has been placed on a layer of salt grains in the container;
directing steam through the packed grains of the salt to form a salt solution about the metal object; and
drying the salt solution to form a powder cake about the metal object.
12 . The method of claim 11 further comprising:
washing the powder cake with liquid water to remove the powder cake from the metal object.
13 . The method of claim 2 further comprising:
generating a signal indicative of a temperature of the temperature of the metal object; and
using the signal to operate a heater that heats the metal object and the supporting structure.
14 . The method of claim 3 further comprising:
filling the container with the granular material to a level sufficient to prevent gravity from deforming features extending from the object.
15 . The method of claim 14 further comprising:
tamping the granular material to increase the density of the granular material about the metal object.
16 . The method of claim 14 further comprising:
filling the container with the granular material to a level that encases the metal object.
17 . The method of claim 16 further comprising:
tamping the granular material to increase the density of the granular material about the metal object.
18 . The method of claim 17 , the tamping of the granular material further comprising:
vibrating the container.
19 . The method of claim 2 , the supporting structure formation further comprising:
pouring a granular material into a container in which the metal object has been placed; and
evaporating a solvent from a solution in the granular material to bind the granular material together.
20 . The method of claim 19 further comprising:
mixing the solution with the granular material before pouring the granular material into the container.
21 . The method of claim 19 further comprising:
mixing a solute with the granular material before pouring the granular material into the container; and
applying a solvent to the mixture of solute and granular material to form the solution with the granular material before evaporating the solvent.
22 . The method of claim 21 , the application of the solvent further comprising:
directing the solvent in one of a vapor form or liquid form through the granular material to form the solution with the granular material.
23 . The method of claim 19 further comprising:
washing the granular material and the solute with the solvent to release the metal object from the granular material and the solute.