Precision Piercing and Blanking of Fiber Reinforced Plastics by Vibro-Punching

Abstract

Summary Vibro-Punching is a newly developed precision shearing process in which the sheet material is punched reciprocatively in the state of half shearing by two couples of punch and die. This process was applied to the punching of the composite materials which can not be sheared precisely by any currently used precison shearing process. Experimental results show that all kinds of test composite materials including glass, carbon, aramid fibers and paper in the plastic-bases such as epoxy, phenol, polyimide polymers etc. can be successfully sheared. Sheared surfaces obtained by this process have a sharp edge without shear droop, an accurate right angle to the sheet surface and a glossy surface with the roughness Rmax of 3 - 8μm. Such a precise surface was confirmed to be copied from the side surfaces of punch and die after the softening of matrix polymer by the local temperature rise at the sheared region due to the friction between the sheared surfaces. This process could be applied to some of thermoplastics, PMMA, PC and ABS which are not punched well by a convetional way. As the other applications of this process, the half shearing and the welding of the polymer and its composite were also confirmed to be achieved by stopping the punch movement in the intermediate stage. The prototype machine was completed for punching the riveting hole of Kevlar composite and CFRP sheets for airplane.