Electrophotography-based additive manufacturing with part molding

Abstract

An additive manufacturing method produces a 3D part utilizes electrophotography-based additive manufacturing and molding processes. A layered structure having a cavity is printed on a build platform using at least one electrophotographic (EP) engine to develop imaged layers of powder material, and a transfusion assembly to stack and fuse the imaged layers on the build platform. Molding material is deposited into the cavity as the layered structure is printed, using a deposition unit. The molding material solidifies to form at least a portion of the 3D part, which may also include portions formed from imaged powder material.

What is claimed is: 
     
         1 . A method of producing a 3D part using an additive manufacturing system comprising steps of:
 printing a layered structure having a cavity on a build platform from a powder material using at least one electrophotographic (EP) engine and a transfusion assembly;   molding a 3D part portion within the cavity including depositing molding material into the cavity using a deposition unit; and   alternating the printing and molding steps multiple times to form a 3D part.   
     
     
         2 . The method according to  claim 1 , wherein the layered structure comprises a sacrificial support material 
     
     
         3 . The method according to  claim 1 , wherein the layered structure comprises a sacrificial support material and a part material. 
     
     
         4 . The method according to  claim 1 , wherein:
 depositing the molding material into the cavity comprises depositing the molding material into the cavity when the molding material is in a powdered state; and   molding a 3D part portion within the cavity comprises heating the molding material within the cavity to fuse together the molding material.   
     
     
         5 . The method according to  claim 4 , wherein molding the 3D part portion within the cavity further comprises pressing the molding material into the cavity. 
     
     
         6 . The method according to  claim 1 , and further comprising cooling the structure on the build platform before each molding step. 
     
     
         7 . The method according to  claim 1 , wherein depositing the molding material into the cavity comprises depositing the molding material into the cavity when the molding material is in a molten state. 
     
     
         8 . The method according to  claim 7 , wherein forming a 3D part portion further comprises cooling the molding material within the cavity. 
     
     
         9 . The method according to  claim 1 , wherein forming the 3D part portion comprises planarizing a top surface of the molding material within the cavity. 
     
     
         10 . The method according to  claim 1 , wherein printing the layered structure comprises:
 forming at least one structure layer using the at least one EP engine;   transferring the at least one structure layer to a transfer medium; and   transfusing each structure layer on the transfer medium to a top structure layer on the build platform.   
     
     
         11 . A method of producing a multi-material 3D part using an additive manufacturing system comprising steps of:
 printing a structure having one or more layers on a build platform comprising:
 forming the one or more imaged layers of powder material using two or more electrophotographic (EP) engines; 
 transferring the one or more layers to a transfer medium; and 
 sequentially transfusing each of the one or more layers on the transfer medium onto the build platform to form a layered structure having one or more cavities; 
 wherein the layered structure includes a sacrificial material portion and a part portion; and 
   forming a molded part portion within the cavity including depositing molding material into a cavity of the structure using a deposition unit; and   repeating the printing and forming steps multiple times to form a combined structure comprising a 3D part and a sacrificial support structure, wherein the 3D part includes the part portion of the layered structure and the molded part portion.   
     
     
         12 . The method according to  claim 11 , wherein:
 depositing the molding material into the cavity comprises depositing the molding material into the cavity when the molding material is in a powdered state; and   forming a molded part portion within the cavity comprises heating the molding material within the cavity to fuse together the molding material.   
     
     
         13 . The method according to  claim 11 , and further comprising cooling the layered structure on the build platform before each forming step. 
     
     
         14 . The method according to  claim 13 , wherein forming a molded part portion comprises at least one of heating the molding material and pressing the molding material into the cavity. 
     
     
         15 . An additive manufacturing system for producing 3D parts comprising:
 a build platform;   an electrophotographic additive manufacturing unit comprising:
 a transfer medium; 
 at least one EP engine configured to develop layers of a powder material and transfer the layers to the transfer medium; and 
 a transfusion assembly configured to build a structure having a cavity on the build platform in a layer-by-layer manner by transferring the developed layers from the transfer medium and fusing them together using heat and pressure; and 
   a deposition unit configured to deposit molding material into the cavity and form a molded part portion of a 3D part within the cavity.   
     
     
         16 . The system according to  claim 15 , wherein the deposition unit includes a heater configured to heat the molding material within the cavity. 
     
     
         17 . The system according to  claim 16 , wherein the deposition unit includes a pressing device configured to engage a top surface of the molding material within the cavity and press the molding material into the cavity. 
     
     
         18 . The system according to  claim 17 , wherein the deposition unit comprises a spreading device configured to spread the molding material into the cavity of the structure on the build platform. 
     
     
         19 . The system according to  claim 15 , further comprising a gantry configured to feed the build platform and the structure between the electrophotographic additive manufacturing unit and the deposition unit along a build path. 
     
     
         20 . The system according to  claim 19 , wherein the build path includes a by-pass route that avoids the deposition unit.