Apparatus for the manufacture of three-dimensional objects

Abstract

An agitator for an apparatus for the manufacture of three-dimensional objects. The agitator comprises at least one blade coupled to a shaft, and extending outwardly from the shaft. Cavities are defined between the at least one blade and the shaft, such that movement of the agitator within a powder repository keeps the powder in a fluidised state and prevents the powder from agglomerating.

1 . An agitator for agitating powder within a powder flow path of an apparatus for manufacturing three-dimensional objects, the agitator configured to at least partially rotate in a direction of rotation about an axis of rotation, within the powder flow path, and comprising:
 a projection extending outwardly substantially at a right angle from the axis of rotation of the agitator;   the projection being arranged to contact the powder during the at least partial rotation of the agitator and to impart a substantially zero net axial directional force on the powder during the at least partial rotation of the agitator, such that the at least partial rotation of the agitator maintains the powder within the powder flow path in a free flowing state.   
     
     
         2 . (canceled) 
     
     
         3 . The agitator of  claim 1 , wherein the projection has a surface area encountered by the powder along the direction of rotation that is less than 50% of an area swept out by the projection along the agitator from an exterior edge of the projection to the axis of rotation (distance AW M /2). 
     
     
         4 . The agitator of  claim 1 , wherein the projection has a surface area encountered by the powder along the direction of rotation that is less than 75% of an area swept out by the projection along the agitator from an exterior edge of the projection to the axis of rotation (distance AW M /2). 
     
     
         5 . (canceled) 
     
     
         6 . The agitator of  claim 1 , wherein the at least one projection extends outwardly from the axis of rotation within a plane perpendicular to the axis of rotation. 
     
     
         7 . The agitator of  claim 1 , wherein the projection comprises a cavity formed within the projection. 
     
     
         8 . The agitator of  claim 7 , wherein the cavity formed within the projection is at least 50% of the area covered by the projection. 
     
     
         9 . The agitator of  claim 1 , wherein the projection extends along a length of the agitator over which the agitator is in contact with the powder. 
     
     
         10 . The agitator of  claim 1 , wherein the projection includes two or more projections provided in a spaced arrangement from one another. 
     
     
         11 . The agitator of  claim 1 , wherein the projection includes two or more projections extending outwardly from the axis of rotation in opposite directions. 
     
     
         12 . The agitator of  claim 1 , wherein the projection includes two or more projections and the agitator further includes a cavity formed between the two or more projections. 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . The agitator of  claim 1 , wherein the projection includes a heat resistant, electrically conductive material. 
     
     
         16 . The agitator of  claim 1 , wherein the projection includes an antistatic polymer. 
     
     
         17 . A stirring device for a powder tank of an apparatus for manufacturing a three-dimensional object, the stirring device configured to rotate within the powder tank about an axis of rotation, and comprising:
 a base plate;   a strut extending from the base plate and arranged to extend from the base plate into the powder tank, the strut forming an obtuse angle facing the direction of rotation.   
     
     
         18 . The stirring device of  claim 14 , further comprising:
 a blade arranged to extend from the strut into the powder tank, and forming an acute angle with the strut.   
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . An apparatus for manufacturing a three-dimensional object comprising:
 a powder flow path;   an agitator configured to agitate powder within the powder flow path, the agitator configured to at least partially rotate about an axis of rotation within the powder flow path; and   a projection extend outwardly from the agitator substantially at a right angle from the axis of rotation of the agitator,   the projection being arranged to contact the powder during the at least partial rotation of the agitator and to impart a substantially zero net axial directional force on the powder during the at least partial rotation of the agitator, such that the at least partial rotation of the agitator maintains the powder within the powder flow path in a free flowing state.   
     
     
         25 . An apparatus for manufacturing a three-dimensional object comprising:
 a powder tank; and   a stirring device for the powder tank, the stirring device configured to rotate within the powder tank about an axis of rotation, and including   a base plate and a strut extend from the base plate into the powder tank, the strut forming an obtuse angle facing the direction of rotation.   
     
     
         26 . The agitator of  claim 1 , wherein the at least one projection is substantially rectangular. 
     
     
         27 . The stirring device of  claim 14 , wherein the strut is arranged to lift powder as the stirring device is rotated about the axis of rotation. 
     
     
         28 . The stirring device of  claim 16 , wherein the strut is arranged to also displace powder axially as the stirring device is rotated about the axis of rotation. 
     
     
         29 . The stirring device of  claim 15 , wherein
 the strut is arranged to lift powder as the stirring device is rotated about the axis of rotation; and   the blade is arranged to displace powder axially as the stirring device is rotated about the axis of rotation.