A machine system for the rapid production of composite structures

A rapid manufacturing process for thermosetting materials was developed to produce composite structures in a manner similar to rapid prototyping. The machine system builds the part layer by layer with continuous curing and co nsolidation, making traditional curing methods unnecessary. Each part layer , which has been prestaged to provide a desired degree of cure, moves under a heat gun and a roller for curing and consolidation. The heat gun initiat es the cure in the part layer, partially curing it and making it tacky enou gh for the next layer to stick to it when it goes through the consolidation process. The cure continues to advance as each layer is placed. Testing wa s performed by fabricating three-layer parts and performing tests on single strips of towpreg to determine how temperature and time affect the degree of cure. The material was IM7 carbon fiber/977-3 epoxy towpreg, prestaged i n a tunnel oven to an approximate 30% degree of cure. Hot air temperatures of 150 - 380 degrees C (302 - 716 degrees F), roller forces of 236 - 472 N (53 - 106 Ibf), table speeds of 13 - 38 mm/sec (0.5 - 1.5 in/sec), and time s of exposure to hot air of 5, 10, and 20 seconds were used. The results sh owed that the machine system can continuously cure and consolidate parts. T he cure was advanced to any level up to 100% degree of cure with an air tem perature of 380 degrees C. Parts were produced with layers well stuck toget her. Within the limitations of the experiments, temperature was determined to be the most significant factor affecting degree of cure. With the correc t processing conditions, the machine system has the capability to produce w ell-consolidated, high quality parts without using traditional curing metho ds. The design of the machine system allows far the addition of components for the fabrication of arbitrarily shaped parts and for different curing me thods.