Heater arrangements and apparatus for layer-by-layer formation of three-dimensional objects

An apparatus for layer-by-layer formation of a three-dimensional object by the consolidation of particulate matter, the apparatus comprising:

• a working space having opposing bottom and top sides;
• a build bed surface arranged on said bottom side of the working space and upon which successive layers of said object are formed;
• and
• a heater arrangement provided on the top side of the working space and having a perimeter defining a heater arrangement area over which heater elements are arranged, wherein the heater arrangement comprises:
• one or more shrouded infrared radiative heating elements, arranged over the heater arrangement area, the shrouded infrared radiative heating elements being operable to heat particulate matter at a build bed surface of said apparatus to a desired temperature profile;
• and
• one or more infrared radiation-absorbing shrouds fitted over the shrouded infrared radiative heating elements, each infrared radiation-absorbing shroud having interior walls forming one or more radiation-absorbing passages, each passage having opposing first and second ends, and arranged such that the first end faces the at least one infrared shrouded radiative element and the second end opens to the exterior so as to face the build bed surface;
• wherein the interior walls of the one or more passages are configured to absorb infrared radiation, and to prevent internal reflection of infrared radiation, emitted from the one or more shrouded infrared radiative heating elements and falling onto the interior walls;
• wherein the interior walls of each passage define a height, a cross sectional shape and a cross sectional area which together restrict the solid angle over which radiation emitted by the shrouded infrared radiative elements emerges from the second end, so as to restrict the footprint of infrared radiation falling onto the build bed surface;
• and
• wherein the heater arrangement faces the build bed surface such that, in a projective view, the perimeter of the heater arrangement is outside the perimeter of the build bed surface, and such that a first group of shrouded heating elements is arranged beyond and around the perimeter of the build bed surface.

An apparatus for layer-by-layer formation of a three-dimensional object by the consolidation of particulate matter, the apparatus further comprising:

• a working space having opposing bottom and top sides;
• a build bed surface arranged on said bottom side of the working space and upon which successive layers of said object are formed;
• and
• a heater arrangement provided on the top side of the working space and having a perimeter defining a heater arrangement area over which heater elements are arranged;
• wherein the heater arrangement comprises:
• a plurality of shrouded infrared radiative heating elements, arranged over the heater arrangement area, the shrouded infrared radiative heating elements being operable to heat particulate matter at a build bed surface of said apparatus to a desired temperature profile;
• and
• a plurality of infrared radiation-absorbing shrouds, each fitted over at least a respective one of the shrouded infrared radiative heating elements, each infrared radiation-absorbing shroud having interior walls forming one or more radiation-absorbing passages, each passage having opposing first and second ends, and arranged such that the first end faces one of the infrared shrouded radiative elements and the second end opens to the exterior so as to face the build bed surface;
• wherein the interior walls of the one or more passages are configured to absorb infrared radiation, and to prevent internal reflection of infrared radiation, emitted from the one or more shrouded infrared radiative heating elements and falling onto the interior walls;
• wherein the interior walls of each passage define a height, a cross sectional shape and a cross sectional area which together restrict the solid angle over which radiation emitted by the shrouded infrared radiative elements emerges from the second end, so as to restrict the footprint of infrared radiation falling onto the build bed surface;
• and
• wherein the shrouded heating elements are spaced apart from one another so as to control an overlap between the radiative footprints of neighboring shrouded heating elements.