Increasing throughput in additive manufacturing using a rotating build platform
An additive manufacturing technique uses digital mask-based illumination and a polar-based build environment for increased throughput. In one embodiment, the build environment comprises a rotating element having a surface. A coater is configured to deposit photopolymer material on the rotating element at a given flow rate. As the element rotates and the coater deposits the photopolymer material, a radiation source of an image scanning system projects an array of point sources (an image) onto the photopolymer material for an exposure time to cure a given layer. As the photopolymer material is deposited layer-upon-layer, and for each layer, a control system adjusts a relative position of the coater with respect to the surface, adjusts a speed of rotation of the rotating element, and maintains the flow rate and the exposure time constant.
1 . A method of additive manufacturing an article, comprising:
providing a rotating element having a surface;
depositing photopolymer material directly on the rotating element at a given flow rate, the photopolymer material being deposited by a coater having an outlet adjacent the surface;
after depositing a given layer, projecting an image onto the photopolymer material for an exposure time to cure the given layer; and
as the photopolymer material is deposited layer-upon-layer, and for each layer: (i) continuously adjusting a relative position of the coater with respect to the surface; (ii) continuously adjusting a speed of rotation of the rotating element; and (iii) maintaining constant the flow rate and the exposure time.
2 . The method as described in claim 1 wherein the coater is translated radially outward based on a thickness h l of the given layer, and a speed u s of the rotating element with respect to one or more previously-deposited and cured layers, wherein the one or more previously-deposited and cured layers have cumulative height h s from the surface, and wherein the speed u s is related to an angular rotation rate {dot over (θ)} of the rotating element by:
u s =( R+h s ){dot over (θ)},
where R is a radius of the rotating element at the surface.
3 . The method as described in claim 1 wherein the photopolymer material is a radiation-curable foam.
4 . The method as described in claim 1 wherein the photopolymer material is cured up to a low gel point.
5 . The method as described in claim 4 wherein the low gel point is between 10-60% gelation, and wherein the given state is greater than approximately 90% cross-linking.
6 . The method as described in claim 1 further including removing the article from the rotating element and continuing to cure the photopolymer material to a given state.
7 . The method as described in claim 6 further including:
removing uncured photopolymer material; and
applying a post-processing operation to cure the photopolymer material to the given state.
8 . The method as described in claim 7 wherein the photopolymer material is cured to the given state by flat curing or by curing in a mold.
9 . A method of additive manufacturing, comprising:
as a support element having a surface rotates, and while maintaining a constant flow rate from an adjacent material outlet and a constant exposure time of an associated radiation source:
depositing a first layer of photopolymer material on the surface;
exposing a first image onto the first layer to cure the first layer;
depositing a second layer of the photopolymer material on top of the cured first layer; and
exposing a second image onto the second layer to cure the second layer;
wherein a relative position of the material outlet with respect to the surface, and wherein a speed of rotation of the element, are adjusted continuously during the depositing and exposing operations.