Three dimensional printer

1. A lamination molding apparatus comprising:

a chamber covering a desired molding region and being filled with an inert gas having a desired concentration;

a recoater head moving in the chamber to supply a material powder on the molding region to form a material powder layer;

a material supplying unit to supply the material powder to the recoater head;

wherein the recoater head comprises: a material holding section to hold the material powder; and a material discharging opening to discharge the material powder in the material holding section;

the material supplying unit comprises: an intermediate duct to supply the material powder to the material holding section; a main duct to supply the intermediate duct with the material powder; and a driving mechanism to move the intermediate duct vertically;

the intermediate duct is configured to be capable of discharging the material powder from an intermediate duct outlet having an elongated shape;

the driving mechanism moves the intermediate duct vertically between a first position in which the intermediate duct outlet is lower than an upper end of the material holding section and a second position in which the intermediate duct outlet is higher than the upper end of the material holding section; and

the material supplying unit is controlled to discharge the material powder from the intermediate duct outlet in a condition where the intermediate duct is moved so that the intermediate duct outlet is located at the first position.

2. The lamination molding apparatus of claim 1 , wherein the material discharging opening has an elongated shape; and

the intermediate duct outlet elongates in a direction substantially the same as the material discharging opening.

3. The lamination molding apparatus of claim 1 , further comprising:

an intermediate duct shutter to open and shut the intermediate duct outlet;

wherein the intermediate duct shutter is controlled so that the intermediate duct outlet is opened in a condition where the intermediate duct outlet is located at a position lower than an upper end of the material holding section.

4. The lamination molding apparatus of claim 3 , wherein the intermediate duct shutter is structured with at least two shutters capable of being controlled independently from each other.

5. The lamination molding apparatus of claim 1 , wherein the intermediate duct comprises: a channel section elongating for a predetermined length from the intermediate duct outlet and having a constant cross-sectional area; and a widened section provided at an upper side of the channel section and having a wider cross-sectional area than the channel section.

6. The lamination molding apparatus of claim 1 , wherein the main duct comprises a main duct lower section and a main duct upper section provided above the main duct lower section;

the material powder supplied to the main duct upper section is supplied to the intermediate duct via the main duct lower section; and

a main duct shutter to open and shut a passage in between the main duct lower section and the main duct upper section is provided.

7. The lamination molding apparatus of claim 6 , wherein the main duct lower section comprises an expanding section, length of the expanding section in a longitudinal direction of the intermediate duct becoming longer as the expanding section comes closer to the intermediate duct.

8. The lamination molding apparatus of claim 1 , wherein the main duct is configured to be capable of moving vertically in accordance with a weight of the material powder maintained in the main duct.