2020 年 61 巻 713 号 p. 138-144
A cup forging method has been developed using discontinuous carbon-fiber-reinforced thermoplastic. Two types of billet have been prepared for the forging. Unidirectional thermoplastic carbon fiber chips of 20 mm length and 10 mm width were randomly laminated and compressed into a circular cylinder. Another billet was made from laminated unidirectional thermoplastic carbon fiber fan-shaped sheets. A forging die was designed for making side holes and side grooves in the cup forging process. In a forging experiment, a cup with side holes and a side groove was forged from discontinuous carbon-fiber-reinforced thermoplastic. Carbon fiber sheets were compressed by the head of the punch and made to flow into the side wall of the cup. Test specimens cut from the side wall of the cup showed a flexion strength of about 400 MPa with a 90 MPa standard deviation. Further study on the relationship between the fiber structure in the billet and that in the forged cup will be necessary to reduce the deviation of the strength of the forged cup.