US 12,269,211 B2
Additive manufacturing process continuous reinforcement fibers and high fiber volume content
Natalie Rudolph, Madison, WI (US); Thomas W. Pfeifer, Madison, WI (US); and Thomas W. C. Laduch, Madison, WI (US)
Assigned to Wisconsin Alumni Research Foundation, Madison, WI (US)
Filed by Wisconsin Alumni Research Foundation, Madison, WI (US)
Filed on May 26, 2016, as Appl. No. 15/165,671.
Prior Publication US 2017/0341300 A1, Nov. 30, 2017
Int. Cl. B29C 64/165 (2017.01); B29B 13/02 (2006.01); B29C 64/118 (2017.01); B29C 64/20 (2017.01); B29C 64/209 (2017.01); B29C 64/218 (2017.01); B29C 64/386 (2017.01); B29C 64/40 (2017.01); B33Y 10/00 (2015.01); B33Y 30/00 (2015.01); B33Y 50/02 (2015.01); B33Y 70/10 (2020.01); B29B 15/12 (2006.01); B29K 63/00 (2006.01); B29K 105/08 (2006.01)
CPC B29C 64/165 (2017.08) [B29B 13/02 (2013.01); B29C 64/118 (2017.08); B29C 64/20 (2017.08); B29C 64/209 (2017.08); B29C 64/386 (2017.08); B29C 64/40 (2017.08); B33Y 10/00 (2014.12); B33Y 30/00 (2014.12); B33Y 50/02 (2014.12); B33Y 70/10 (2020.01); B29B 15/122 (2013.01); B29K 2063/00 (2013.01); B29K 2105/08 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method of additive manufacturing comprising:
(a) impregnating reinforcing fibers extending along a filament axis with an uncured thermoset material having a first reaction temperature and a second higher reaction temperature to produce an impregnated three-state filament where the fibers are multi-stranded, substantially parallel to the filament axis and have a length of at least 50 mm and comprise at least 50 percent of a volume of the filament, the thermoset material providing: (1) a first state with an uncompleted first chemical reaction between a first reactant and a second reactant in the thermoset material and an uninitiated second chemical reaction with a third reactant in the thermoset material, (2) a second state having the first chemical reaction completed and the second chemical reaction uninitiated so that the filament has an adhesive outer surface, and (3) a third state with the first chemical reaction and the second chemical reaction completed;
(b) heating the impregnated filament to the first reaction temperature but less than the second higher reaction temperature to transition the filament from the first state to the second state;
(c) cooling the filament in the second state to provide mechanical tractability with reduced adhesion in the outer surface;
(d) using a roller to conduct the cooled filament in the second state to a print surface;
(e) reheating the filament to restore adhesion without completion of the cure of the thermoset material;
(f) applying the filament in the second state in multiple layers over an area to construct a three-dimensional object of filament segments retained in position by inter-engagement of their outer adhesive surfaces; and
(g) heating the three-dimensional object to the second higher reaction temperature to transition the filament from the second state to the third state;
wherein, the heating of step (b) is performed in a pultrusion die in which the reinforcing fibers are impregnated with the uncured thermoset material;
further including, a step of pulling the fibers during steps (a) and (b) using at least one motorized roller engaging the impregnated filament downstream the cooling of step (c);
wherein, the motorized roller provides a substantially constant rate of pulling of the fibers during steps (a) and (b) and further including, a take-up guide having a first guiding surface and a second guiding surface providing a variable separation therebetween and receiving filament after the motorized roller to temporarily store variable amounts of filament in the variable separation before it is applied at step (e) when an application rate of the three-state filament to a previous layer differs from the constant rate of pulling of the fibers.