Reduction in Vibro-Punching Time of Carbon-Fiber-Reinforced Thermoplastic Sheets Using Numerical Control Servo Press Machine

Abstract

Obtaining cut surfaces with high precision by shearing, including press cutting and punching, of composite materials such as carbon-fiber-reinforced thermoplastic (CFRTP) is difficult because shear characteristics vary among materials. To address this problem, vibratory finish shearing and shaving have been examined. However, conventional vibratory finish shearing requires a dedicated press machine and conventional shaving requires two processes. The authors have proposed a simple punching method for CFRTP sheets involving the low-frequency vibrational motion of a punch using a numerical control (NC) servo press machine that has recently become widespread. The method realizes high-precision punching in a single process using conventional dies. However, it takes a long time to achieve the desired cut surface. Therefore, the time required for punching should be reduced before this method is practically applied. In this study, experiments were carried out to determine the optimal vibrational conditions of the punch for achieving high-precision cut surfaces of holes within a short period of time. The conditions required for vibro-punching to be completed within ~16 s, which is the allowable time for deep drawing of CFRTP sheets using a hot press, were determined.