Installation for fabricating parts by selective melting of powder

1. An installation for fabricating parts by selective melting of powder, comprising:

a vessel including a bottom constituted by a rectangular movable plate which is moved by a movable support, the movable plate including a top face facing into the vessel and a bottom face facing towards the movable support, the bottom face including first, second, third, and fourth rims which extend downwards from peripheral edges of the movable plate;

means for bringing powder into the vessel;

means for generating and moving a laser beam or an electron beam that is configured to give rise to selective melting of the powder in the vessel; and

tensioning means for tensioning the movable plate in at least one direction parallel to a plane of the movable plate,

wherein the tensioning means are provided in a space defined by the first, second, third and fourth rims and

wherein a vertical distance between the bottom face of the movable plate and the movable support is greater than a vertical distance between the bottom face of the movable plate and the tensioning means.

2. An installation according to claim 1 , wherein the tensioning means is configured to subject the movable plate to tension forces oriented along first and second directions which are perpendicular to each other.

3. An installation according to claim 2 , wherein the tension forces are parallel to two sides of the movable plate.

4. An installation according to claim 1 , wherein the tensioning means includes at least one actuator applying a force via at least one edge of the movable plate.

5. An installation according to claim 1 , further comprising a force-spreader spacer mounted between the rim of the movable plate and the tensioning means.

6. An installation according to claim 1 , wherein the movable plate has a thickness in a range of 3 mm to 10 mm.

7. An installation according to claim 1 , wherein the tensioning means is mounted on the movable support under the movable plate.

8. An installation according to claim 1 , wherein each rim being subjected to a force generated by the tensioning means.

9. An installation for fabricating parts by selective melting of powder, comprising:

a vessel including a bottom constituted by a rectangular movable plate which is moved by a movable support, the movable plate including a top face facing into the vessel and a. bottom face facing towards the movable support, the bottom face including first, second, third, and fourth rims which extend downwards from peripheral edges of the movable plate;

a scraper which brings the powder from a tank into the vessel;

a device which generates and moves a laser beam or an electron beam that is configured to give rise to selective melting of the powder in the vessel;

first, second, third, and fourth spacers respectively disposed against each rim of the movable plate;

a first actuator with a first end pressing against the first rim via the first spacer and a second end pressing against the second rim via the second spacer; and

a second actuator with a first end pressing against the third rim via the third spacer and a second end pressing against the fourth rim via the fourth spacer,

wherein the movable plate is tensioned in a horizontal plane due to forces generated by the first and second actuators,

wherein the first and second actuators and the first, second, third, and fourth spacers are provided in a space defined by the first, second, third, and fourth rims, and

wherein a vertical distance between the bottom face of the movable plate and the movable support is greater than a vertical distance between the bottom face of the movable plate and an upper surface of one of the first, second, third and fourth spacers.