Method of layerwise fabrication of a three-dimensional object

Abstract

A method of layerwise fabrication of a three-dimensional object is disclosed. The method comprises, for each of at least a few of the layers: dispensing at least a first modeling formulation and a second modeling formulation to form a core region using both the first and the second modeling formulations, and at least one envelope region at least partially surrounding the core region using one of the first and the second modeling formulations but not the other one of the first and the second modeling formulations. The method can also comprise exposing the layer to curing energy. The first modeling formulation is characterized, when hardened, by heat deflection temperature (HDT) of at least 90° C., and the second modeling formulation is characterized, when hardened, by Izod impact resistance (IR) value of at least 45 J/m.

What is claimed is: 
     
         1 . A three-dimensional printing system, comprising:
 a plurality of inkjet printing heads each having a circuit for controllably dispensing building materials;   a tray for receiving building materials dispensed by said inkjet printing heads;   a curing device configured for applying curing energy;   a thermal screen for thermally separating said circuits from a building space between said inkjet printing heads and said tray; and   a heating system for heating said building space.   
     
     
         2 . The system of  claim 1 , wherein said heating system comprises a source of thermal radiation positioned in said building space to deliver heat to said dispensed building material by radiation. 
     
     
         3 . The system of  claim 2 , wherein said source of thermal radiation is configured to heat to a temperature of from about 40° C. to about 900° C. 
     
     
         4 . The system of  claim 1 , wherein said heating system comprises a blower positioned outside said building space for delivering heat to said dispensed building material by convection. 
     
     
         5 . The system of  claim 1 , wherein said heating system comprises a tray heater in thermal contact with a back side of said tray for delivering heat to said dispensed building material by heat conduction. 
     
     
         6 . The system of  claim 5 , comprising a temperature sensor for sensing a temperature of said tray heater, and a heating system control circuit for dynamically controlling said tray heater responsively to signals received from said temperature sensor. 
     
     
         7 . The system of  claim 5 , wherein said tray heater is configured to heat to a temperature of from about 40° C. to about 100° C. 
     
     
         8 . The system of  claim 1 , wherein said heating system comprises a plurality of heating mechanisms, each being selected from the group consisting of: (i) a source of thermal radiation positioned in said building space to deliver heat to said dispensed building material by radiation, (ii) a blower positioned outside said building space for delivering heat to said dispensed building material by convection, and (iii) a tray heater in thermal contact with a back side of said tray for delivering heat to said dispensed building material by heat conduction. 
     
     
         9 . The system of  claim 8 , comprising a controller configured to select and operate at least one of said heating mechanisms. 
     
     
         10 . The system of  claim 8 , comprising a user interface configured to allow a user to select one of several heating modes for the system, wherein said controller is configured to select and operate said at least one of said heating mechanisms responsively to said user selection. 
     
     
         11 . The system of  claim 1 , wherein said thermal screen is foldable and collapsible. 
     
     
         12 . The system of  claim 11 , wherein said thermal screen is positioned to simultaneously fold at one side of said inkjet printing heads and expand at an opposite side of inkjet printing heads during a motion of said inkjet printing heads. 
     
     
         13 . The system of  claim 11 , wherein said thermal screen is an accordion folding screen. 
     
     
         14 . The system of  claim 11 , wherein said thermal screen is a telescopic screen. 
     
     
         15 . The system of  claim 1 , comprising a controller configured to establish a linear relative motion between said tray and said printing heads. 
     
     
         16 . The system of  claim 1 , comprising a controller configured to establish a rotary relative motion between said tray and said printing heads. 
     
     
         17 . The system of  claim 1 , comprising a leveling device for leveling and/or establishing a height of said building materials after said dispensing, and a leveling device control circuit configured for controlling said leveling device, and being thermally separated from said building space by said thermal screen. 
     
     
         18 . The system of  claim 1 , comprising a curing device control circuit, configured for controlling said curing device and being thermally separated from said building space by said thermal screen. 
     
     
         19 . The system of  claim 1 , wherein said thermal screen comprises a thermally reflective material. 
     
     
         20 . A method of printing a three-dimensional object, comprising:
 receiving computer object data describing a plurality of slices of the object; and   operating the system of  claim 1  to dispense said building materials by said printing heads and to cure said building materials by said curing device, so as to form a plurality of layers each according to a configured pattern corresponding to a slice of said computer object data.