열간 링 압축 시험의 시편크기, 금형속도, 냉각조건이 마찰 보정선도에 미치는 영향

The friction is a critical factor influencing the forged shape and forging load in hot closed die forging such as hot extrusion. The purpose of this study is to establish the hot ring compression test for the effect of friction on the forged shape and forging load in hot forging process. In order to do it, the comprehensive finite element analyses were carried out to evaluate the effect of various variables such as specimen size, die speed and cooling time on the friction calibration curve of hot ring compression test. From these results, it was found that the stability of friction calibration curve could be secured through the increase of specimen size and adjustment of die speed with the specimen size.