Isothermal Forming of CFRTP Sheet by Penetration of Hemispherical Punch

Abstract

An isothermal forming system for carbon fiber reinforced thermoplastic (CFRTP) has been developed to investigate CFRTP press forming behavior. The formability of CFRTP has been tested by Deep drawing with hemispherical punch, 10 mm/min. stroke rate. Twill weaved CF/PA66 fabric composite sheets were formed into the hemispherical shape with different blankholder pressures from 1.2 to 6.0 MPa at the testing temperature from 180 oC to 240 oC in the isothermal condition. The drawing depth strongly depends on the test temperature. If the test temperature decreased under 200 oC, the crack occurred at the crown. If it increased over 220 oC, crack occurred at the fringe of bending part. Shear deformation occurred in bias directions. This kind of behaviors was observed by micro structure inspection. The optimum blankholder pressure minimizes the occurrence of wrinkle at 220 oC.