Method and apparatus for producing three-dimensional objects by selectively solidifying a build material applied layer by layer

An apparatus for producing a three-dimensional object by selectively solidifying a build material, applied layer by layer, using a beam acting on the build material, the apparatus comprising:

• a process chamber comprising a build platform, arranged in an X/Y plane and on which the three-dimensional object is created,
• a radiation source for generating the beam,
• at least one beam guiding element for guiding and directing the beam onto the build material to be solidified, wherein the beam is capable of being coupled into the process chamber through a beam inlet opening of the process chamber above the build platform,
• a process assistance device comprising a centre module and at least one outer module, aligned with the centre module, for facilitating a primary gas flow between the at least one outer module and the centre module along a section of the build platform, and
• a feed device disposed above the build platform for feeding a secondary gas flow through a feed opening of the feed device onto the build platform the feed device comprising two feed channels disposed on either side of the beam inlet opening, wherein the feed opening adjoins or surrounds the beam inlet opening,
• wherein the process chamber comprises two wall portions opposing each other in an X direction, each wall portion having a flow surface that extends toward the build platform, wherein the flow surfaces of the two wall portions constrict a cross-sectional area of the process chamber in the X direction, and wherein proceeding from the feed opening of the feed device, a distance between the flow surfaces of the two wall portions in the X direction progressively reduces towards the build platform.