Method for manufacturing three-dimensional shaped object and three-dimensional shaped object obtained by the same

1. A method for manufacturing a three-dimensional shaped object, the method comprising the repeated steps of:

(i) forming a solidified layer by irradiating a predetermined portion of a powder layer on a base plate with a light beam, thereby allowing a sintering of the powder in the predetermined portion or a melting and subsequent solidification thereof; and

(ii) forming another solidified layer by newly forming a powder layer on the resulting solidified layer, followed by the irradiation of a predetermined portion of the powder layer with the light beam;

wherein the solidified layers are formed such that they have high-density portions whose solidified density is 95 to 100% and a low-density portion whose solidified density is 0 to 95% (excluding 95%); and

wherein one of the high-density portions is a portion of the three-dimensional shaped object, to which the force is applied when the three-dimensional shaped object is used, and the other of the high-density portions is a heat-transfer portion of the three-dimensional shaped object in use; and

wherein the portion to which the force is applied when the three-dimensional shaped object is used and the heat-transfer portion of the three-dimensional shaped object in use are connected each other via a high-density sintered portion.

2. The method according to claim 1 , wherein the high-density portion is formed due to a complete melting of the powder in the predetermined portion.

3. The method according to claim 1 , wherein the low-density portion has the solidified density of 70 to 90%.

4. The method according to claim 1 , wherein the high-density portion is formed in a part of the surface region of the three-dimensional shaped object.

5. The method according to claim 1 , wherein the high-density portion is formed in a portion of the three-dimensional shaped object, the portion being in contact with the base plate.

6. The method according to claim 1 , wherein the high-density portion is formed in a part of the interior portion of the three-dimensional shaped object.

7. The method according to claim 1 , wherein the high-density portion “a” is formed in a part of the surface region of the three-dimensional shape, whereas the high-density portion “b” is formed in a portion of the three-dimensional shaped object, the portion “b” being in contact with the base plate; and

at least one high-density portion “c” is formed in a part of the interior portion of the three-dimensional shaped object so that the high-density portion “a” and the high-density portion “b” are connected to each other via the high-density portion “c”;

the high-density portions “a” and “b” are the portions of the three-dimensional shaped object, to which the force is applied when the three-dimensional shaped object is used, whereas the high-density portion “c” is the heat-transfer portion of the three-dimensional shaped object in use.

8. A three-dimensional shaped object obtained by the method according to claim 4 , wherein the three-dimensional shaped object is used as a metal mold, and said part of the surface region of the three-dimensional shaped object corresponds to a cavity-forming surface of the metal mold.

9. A three-dimensional shaped object obtained by the method according to claim 6 , wherein the three-dimensional shaped object is used as a metal mold, and said part of the interior portion of the three-dimensional shaped object corresponds to a wall of a cooling water channel of the metal mold.

10. A three-dimensional shaped object obtained by the method according to claim 7 , wherein the three-dimensional shaped object is used as a metal mold, and a joint portion of the high-density portion “a” and the high-density portion “c” is a portion of the three-dimensional shaped object, to which the force is applied when the three-dimensional shaped object is used.