アルミニウム円管端末の球面状口広げ成形中に生じるカーリング現象

Abstract

The curling behavior in aluminun was investigated to clarify the condition for curling during the tube end spherical flaring. The influence of die radius R, lubricant, ratio of the tube wall thickness to diameter t0/d0, work hardening exponent n and forming speed V on the condition for curling was investigated in the aluminum tubes. It was found that the curling took place when the apparent die angle α' at the initial contact point of a tubular specimen to the hemispherical die was larger than the critical die angle αS with the conical die. Furthermore, the multi- and single-stage methods to prevent the curling in the case of the conical die were proposed and experimentally examined. The curling mode was prevented under the proposed preventing condition. Thus, these results suggested that the curling mechanism in the hemispherical die was similar to that in the conical die.