Method and device for producing three-dimensional objects

Abstract

A method for producing three-dimensional objects layer by layer using a powdery material which can be solidified by irradiating it with at least two electron beams, said method comprises a pre-heating step, wherein the pre-heating step comprises the sub-step of scanning a pre-heating powder layer area (100) by scanning a first electron beam in a first region (I) and by scanning a second electron beam in a second region (II) distributed over the pre-heating powder layer area (100), wherein consecutively scanned paths are separated by, at least, a security distance (ΔY), said sub-step further comprising the step of synchronising the preheating of said first and second electron beams when simultaneously preheating said powder material within said first and second regions respectively, so that said first and second electron beams are always separated to each other with at least a minimum security distance (ΔX).

1 . A computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program code portions embodied therein, the computer-readable program code portions comprising one or more executable portions configured for:
 scanning a powder layer area by scanning a first electron beam in a first region along a first series of paths and by scanning a second electron beam in a second region along a second series of paths distributed over the powder layer area, wherein consecutively scanned paths in each of the first and second series of paths are separated by, at least, a security distance, said security distance being adapted to prevent a pre-heated powder in said first and second regions respectively to exceed a maximum charge density, above which discharge will occur, from said consecutively scanned paths; and   synchronizing a movement of said first and second electron beams when simultaneously preheating powdery material within said first and second regions respectively, so that said first and second electron beams are always separated from each other by at least a minimum security distance, said minimum security distance being adapted to prevent a sum of a charge distribution in the powdery material from reaching a critical point at which powder particles start to repel each other.   
     
     
         2 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for re-scanning the first and second regions of the powder layer area. 
     
     
         3 . The computer program product of  claim 2 , wherein paths followed during a re-scan of the powder layer area are displaced an interspacing distance in relation to the paths followed during a previous scan of the powder layer area, wherein the interspacing distance is less than the security distance. 
     
     
         4 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for increasing the power of at least one of said first or second electron beam when pre-heating the powdery material. 
     
     
         5 . The computer program product of  claim 4 , wherein the one or more executable portions of the computer-readable program code portions are further configured for increasing the power of at least one of said first or second electron beam when pre-heating the powdery material by increasing beam current of the at least one of said first or second electron beam. 
     
     
         6 . The computer program product of  claim 2 , wherein the one or more executable portions of the computer-readable program code portions are further configured for stepwise increasing the power of at least one of the first or the second electron beam between consecutive scans or re-scans of the powder layer area. 
     
     
         7 . The computer program product of  claim 6 , wherein the one or more executable portions of the computer-readable program code portions are further configured for increasing the power of at least one of said first or second electron beam by increasing beam current of the at least one of said first or second electron beam. 
     
     
         8 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for scanning the first series of paths from a first end to a second end and the scanning the second series of paths from the second end to a third end. 
     
     
         9 . The computer program product of  claim 1 , wherein the first series of paths and the second series of paths are parallel. 
     
     
         10 . The computer program product of  claim 1 , wherein the first series of paths and the second series of paths form straight lines. 
     
     
         11 . The computer program product of  claim 1 , wherein the powder layer area is larger than, and thereby forms a security margin with respect to, a corresponding part of the powder layer that is to be fused. 
     
     
         12 . The computer program product of  claim 11 , wherein the powder layer area has a different shape than the corresponding part of the powder layer that is to be fused. 
     
     
         13 . The computer program product of  claim 11 , wherein the powder layer area has a same shape as the corresponding part of the powder layer that is to be fused. 
     
     
         14 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for pre-heating the powder layer area in a homogeneous manner to elevate the powder layer area to a predetermined temperature, which temperature is below the melting temperature of the powdery material. 
     
     
         15 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for fusing together the powdery material. 
     
     
         16 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for scanning the first electron beam and the second electron beam such that only one of the first or second electron beams are within a corridor at a time, wherein the corridor is a portion of the powder layer area including a border between the first region and the second region and at least a portion of the first region and the second region. 
     
     
         17 . The computer program product of  claim 1 , wherein the minimum security distance is larger than the security distance. 
     
     
         18 . The computer program product of  claim 1 , wherein the one or more executable portions of the computer-readable program code portions are further configured for scanning the first electron beam between at least a first extreme position and at least a second extreme position, wherein the first extreme position and the second extreme position define the first region. 
     
     
         19 . The computer program product of  claim 18 , wherein the one or more executable portions of the computer-readable program code portions are further configured for scanning the second electron beam between at least a third extreme position and at least a fourth extreme position, wherein the third extreme position and the fourth extreme position define the second region. 
     
     
         20 . The computer program product of  claim 19 , wherein at least one of the first or second extreme position overlaps at least one of the third or fourth extreme position.