Method for manufacturing three-dimensionally shaped object, three-dimensionally shaped object obtained thereby, and method for manufacturing molded article

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

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

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 a part of a surface portion of the three-dimensional shaped object is formed as a low-density solidified portion whose solidified density ranges from 50% to 90% so that an application of pressure can be performed by a gas flowing through the low-density solidified portion;

and the method further comprising:

forming a hollow portion in the three-dimensional shaped object such that the hollow portion communicates with the low-density solidified portion; and

forming, in a partial space of the hollow portion, a supporting solidified portion defined by a sintered portion, wherein the supporting solidified portion supports and is connected to the low-density solidified portion.

2. The method according to claim 1 , wherein the low-density solidified portion with its thickness of 0.5 to 10 mm is formed.

3. A three-dimensional shaped object obtained by the method according to claim 1 , used as a core metal mold or a cavity metal mold;

wherein at least a part of a cavity-forming surface of the metal mold is provided with a low-density solidified portion whose solidified density ranges from 50% to 90%, and thereby an application of pressure with respect to a raw material for molding or a molded article can be performed by a gas flowing through the low-density solidified portion.

4. The three-dimensional shaped object according to claim 3 , further comprising the hollow portion, which is in communication with the low-density solidified portion, being provided in communication with an outside of the shaped object.

5. The three-dimensional shaped object according to claim 3 , wherein a thickness of the low-density solidified portion is locally different.

6. A method for manufacturing a molded article by using of the three-dimensional shaped object obtained by the method according to claim 1 as a metal mold, the method comprising:

injecting a raw resin material into a cavity of the metal mold; and

subjecting the raw resin material to a molding process in the cavity of the metal mold;

wherein pressure is applied from the outside of the cavity with respect to the raw resin material or a molded article obtained therefrom by supplying a gas via the low-density solidified portion.

7. The method according to claim 6 , wherein a temperature of the raw resin material or the molded article in the cavity is adjusted by making use of a temperature of the gas.

8. The method according to claim 6 , wherein the application of the pressure by the gas supply is performed in each of an injection/pressure-keeping process and a demold process, the pressure being gas pressures different from each other with respect to the injection/pressure-keeping process and the demold process.

9. The method according to claim 1 , comprising the supporting solidified portion being formed by a plurality of spaced apart sintered portions.

10. The method according to claim 9 , wherein the plurality of spaced apart sintered portions is spaced apart at regular intervals.

11. The method according to claim 9 , wherein ends of the plurality of spaced apart sintered portions support the low-density solidified portion such that the low-density solidified portion is positioned above the plurality of spaced apart sintered portions that are provided within the hollow portion.