Methods and apparatus for three-dimensional printed composites based on flattened substrate sheets
A 3D object according to the invention involves substrate layers infiltrated by a hardened material. The 3D object may be fabricated by a method comprising the following steps: Flatten a substrate layer. Position powder on all or part of a substrate layer. Repeat this step for the remaining substrate layers. Stack the substrate layers. Transform the powder into a substance that flows and subsequently hardens into the hardened material. The hardened material solidifies in a spatial pattern that infiltrates positive regions in the substrate layers and does not infiltrate negative regions in the substrate layers. In a preferred embodiment, the substrate is carbon fiber and excess substrate is removed by abrasion. Flattening a substrate layer involves reducing planar inconsistencies or imperfections, and comprises applying heat to each substrate layer, cooling the substrate layers, and optionally applying tension and/or pressure to the heated and cooled substrate layers.
1. A system for fabricating a three-dimensional (3D) object, comprising:
a means for pre-processing each of a plurality of substrate sheets to reduce planar inconsistencies or imperfections, wherein a substrate sheet comprises a binder and corresponds to a layer of the 3D object, and wherein each substrate sheet is heated to a temperature greater than the substrate sheet's binder glass transition temperature or melting point, and then subsequently cooled below the substrate sheet's binder glass transition temperature or melting point
a dispenser for selectively depositing an adhering agent in a desired pattern onto portions of a pre-processed substrate sheet for each layer;
an applicator for applying powder on areas of each of the plurality of substrate sheets corresponding to both regions where the adhering agent is selectively deposited and regions where the adhering agent is not selectively deposited;
a mechanism for removing loose powder; and
an alignment mechanism for stacking the substrate sheets in a predetermined order for creating the 3D object.
2. The system of claim 1 , wherein the means for pre-processing is an electrically heated platen configured to heat the substrate sheets to a temperature greater than the binder's glass transition temperature or melting point, and circulating air cooling configured to subsequently cool the substrate sheets to a temperature below the binders glass transition temperature or melting point.
3. The system of claim 1 , wherein the plurality of substrate layers comprise carbon fiber.
4. The system of claim 1 , wherein the pre-processing comprises flattening by application of heat, pressure, tension, or a combination thereof, to each of the plurality of substrate sheets.
5. The system of claim 1 , wherein the pre-processing comprises processing the plurality of substrate layers such that the planar inconsistencies or imperfections of each layer are reduced so as not to exceed a defined range of variation above or below a target dimension based on an initial design specification of the 3D object.
6. The system of claim 1 , wherein the removal of loose powder includes removing the powder from the portion of the substrate layer to which the adhering agent was not applied.
7. The system of claim 1 , wherein the planar inconsistencies or imperfections comprise local waviness, crimping, wrinkling, or a combination thereof.
8. The system of claim 1 , wherein the planar inconsistencies or imperfections are present in the substrate layers due to an original manufacturing process, temperature changes following an original manufacturing process, or due to relative motion of fibers of the substrate layers in storage as the fibers conform to a particular shape.