Apparatus and method for fabricating three-dimensional objects

1. An apparatus for making three-dimensional physical objects of predetermined shape by sequentially depositing layers of solidifying material in a desired pattern, the apparatus comprising:

a frame;

a base member for receiving the solidifying material, the base member mounted to the frame for movement in a z-direction;

a gantry assembly mounted to the frame for movement in an x, y plane orthogonal to the z-direction, the gantry assembly including

a print carriage mounted to the gantry assembly for movement in the x, y plane, the print carriage including a dispensing head having a flow passage therein in flow communication at one end thereof with a dispensing outlet configured in the form of a tip with a discharge orifice for dispensing the solidifying material in a fluid state on the base member;

a supply of flexible strand of thermoplastic resin material that solidifies by cooling to a solidification temperature upon being dispensed onto the base member;

means for supplying the material in a fluid state through the flow passage to the dispensing outlet;

a pair of motors mounted to the frame for moving the print carriage relative to the base member in the x,y plane in a predetermined sequence and pattern, each motor of the pair of motors comprising

a rotating drive pulley, and

a drive cable connected at each end of the drive cable to opposite sides of the print carriage, the drive pulley operatively advancing the drive cable upon rotation of the drive pulley in either direction; and

means for metering the discharge of the material in a fluid state from the discharge orifice onto the base member as the dispensing head and base member are moved relative to each other so as to thus form a three-dimensional object,

wherein the material is provided to the movable dispensing head in the form of a continuous flexible strand,

wherein the means for supplying the material in a fluid state comprises a heater on the dispensing head proximate the flow passage that heats the flexible strand to a predetermined temperature above the solidification temperature of the material,

wherein the means for metering comprises a material advance mechanism operatively associated with the flexible strand which controllably advances the flexible strand towards the flow passage at an advance rate controlled in relation to the mechanism, to thereby regulate the flow rate of the material in a fluid stream from the discharge orifice in relation to the relative movement of the discharge head and the base member, and

wherein each drive pulley has an axial passage radially spaced from a central longitudinal axis of the drive pulley, and a transverse passage at each end of the pulley extending between the axial passage and a periphery of the pulley, wherein the drive cable is wrapped on the periphery of the pulley at one end of the pulley in a first direction, passes through the transverse passage at the one end of the pulley, passes through the axial passage, passes through the transverse passage at another end of the pulley and is wrapped on the periphery of the drive pulley at the other end of the pulley in a direction opposite to the first direction.

2. The apparatus as recited in claim 1 , wherein the base member has a print surface, and further comprising a multi-zone heater for distributing power to a plurality of zones of the print surface for maintaining the print surface at a uniform temperature.

3. The apparatus as recited in claim 1 , wherein each motor comprises a stepper motor.

4. The apparatus as recited in claim 1 , wherein each motor comprises a closed-loop servomotor.

5. The apparatus as recited in claim 1 , wherein the periphery of each drive pulley is smooth.

6. The apparatus as recited in claim 2 , wherein the multi-zone heater comprises a kapton film.

7. The apparatus as recited in claim 2 , wherein the multi-zone heater comprises a silicone mat resistance heater.