PRODUCTION OF NEAR NET SHAPED PREFORMS FROMCHOPPED FRTP HYBRID ROVINGS

摘要

Manufacturing near net shaped preforms from fiber reinforced thermoplastics (FRTP) allows thernproduction of highly loadable composite components economically. A modified chopper gun isrnused to chop the thermoplastic hybrid rovings that consist of polypropylene and glass filaments.rnThe chopper gun combines high chopping rates with flexible use. Hot air to melt thernthermoplastic matrix and applied vacuum over the preform screen help to fix the fibers on arntooling system.rnThe process control has to meet the requirements concerning the fixation of the fibers on thernmold. The chopper gun produces up to 5 kg cut hybrid rovings per minute that have to be fixed.rnTo be able to demould the preform and get a manageable material to move it to the followingrnconsolidation processes (pressing, diaphragm forming or vacuum bagging) the thermoplasticrnfibers are molten locally by hot air. The preform becomes stable after cooling down below thernmelting temperature of the matrix material.