Method and apparatus for manufacturing a three-dimensional object

A method of manufacturing a three-dimensional object by a layer-by-layer application and selective solidification of a building material, comprising the steps of:

• applying a layer of the building material to a build area in a process chamber;
• selectively solidifying those points of the applied layer which correspond to the cross-section of the object in this layer by exposure to a radiation;
• repeating the steps of applying and selectively solidifying until the three-dimensional object is completed;
• arranging a hollow body in the process chamber above the build area, the hollow body substantially extending from the build area in a direction of a top of the process chamber;
• and
• supplying gas to the process chamber and discharging gas from the process chamber in such a manner that a lower pressure exists in the region of the process chamber lying within the hollow body than in the region of the process chamber lying outside the hollow body,
• wherein a gas pressure which is higher than the pressure outside the process chamber is applied in the region of the process chamber lying outside the hollow body;
• wherein due to the lower pressure within the hollow body, gas streams in from the region of the process chamber lying outside the hollow body through a first gap between the build area and the lower side of the hollow body into the region of the process chamber lying within the hollow body;
• and/or
• wherein due to the lower pressure within the hollow body, gas streams in from the region of the process chamber lying outside the hollow body through a second gap between the top of the process chamber and an upper side of the hollow body into the region of the process chamber lying within the hollow body.