Arrangement and method for producing a three-dimensional product

Abstract

A method and arrangement for production of three-dimensional bodies by successive fusing together of selected areas of a powder bed, which parts correspond to successive cross sections of the three-dimensional body, which method comprises the following method steps: application of powder layers to a work table, supplying energy from a radiation gun according to an operating scheme determined for the powder layer to said selected area within the powder layer, fusing together that area of the powder layer selected according to said operating scheme for forming a cross section of said three-dimensional body, a three-dimensional body being formed by successive fusing together of successively formed cross sections from successively applied powder layers.

1 . An arrangement for producing a three-dimensional product, the arrangement comprising:
 a work table where said three-dimensional product is built up,   a powder dispenser which forms a powder bed by distributing a thin layer of powder on the work table,   a radiation gun that supplies energy to the powder   a beam guide that guides a beam emitted by the radiation gun such that said beam forms a cross section of said three-dimensional product by successively fusing together selected areas of said powder bed, and   a control computer which
 stores information about successive cross sections of the three-dimensional product, and 
 controls said beam guide according to an operating scheme such that the beam guide moves a focal point of the emitted beam between two or more geometrically separate positions of said selected area, thereby alternately supplying energy to said separate positions and creating two or more fusion zones in said selected area, the fusion zones propagating simultaneously through the selected area during formation of a cross section of said three-dimensional product. 
   
     
     
         2 . The arrangement as claimed in  claim 1 , where the operating scheme guides the focal point of the emitted beam at said fusion zones at a propagation speed which corresponds to a wave propagation speed of the fusion zone. 
     
     
         3 . The arrangement as claimed in  claim 2 , where the control computer estimates said wave propagation speed from information provided by measuring the temperature distribution of a surface layer of said selected area. 
     
     
         4 . The arrangement as claimed in  claim 2 , where the control computer estimates said wave propagation speed by calculating an energy balance for an area comprising said geometrically separate positions, said wave propagation speed being obtained from a model of a thermal conductivity equation set up for said area. 
     
     
         5 . The arrangement as claimed in  claim 1 , where the control computer calculates an energy balance for at least one part area within each powder layer, and determines, in the calculation, whether energy radiated into the part area is sufficient to maintain a defined working temperature of the part area. 
     
     
         6 . The arrangement as claimed in  claim 5 , the control computer controls said beam guide such that, in addition to supplying energy for fusing together powder layers, said radiation gun supplies energy for heating the part area to a defined working temperature if the result of the energy balance calculation is that the operating scheme provides insufficient energy for maintaining the part area at the defined working temperature. 
     
     
         7 . The arrangement as claimed in  claim 1 , the arrangement further comprising a surface layer temperature distribution sensor that senses the temperature distribution of a surface layer of said selected area.