US Patent 8187521 Method and device for producing three-dimensional objects

A method for producing three-dimensional objects from a powder material which is capable of solidification by irradiation with a high-energy beam is disclosed. The method comprises homogeneously pre-heating the powder material by scanning with the high-energy beam along predetermined paths over a pre-heating area so that consecutive paths are separated by a minimum security distance which is adapted to prevent undesirable summation effects in the pre-heating area, and then solidifying the powder material by fusing together the powder material. Apparatus for producing such three-dimensional objects is also disclosed.