이종금속접합에 의한 Steel 보강재가 포함된 중공형 구상흑연주철 크랭크샤프트의 신뢰성 평가

Abstract

Conventional way of manufacturing crankshafts for heavy duty engines by forging steel is costly and timeconsuming. To meet explosively increasing demands for the crankshafts worldwide, totally new design of the crankshafts is suggested, which is a hollow DCI( ductile cast iron) crankshaft with reinforcing steel members utilizing joining technology of two different metals which are steel and DCI. Seamlessly putting reinforcing steel members around crank pins, crank journals and in the center as oil holes together is devised to overcome the inferiority of DCI to forged steel in terms of mechanical properties such as elongation and fatigue. Finite element method is used to veritY relative reliability of a hollow DCI crankshaft with reinforcing steel members over a conventional solid forged steel crankshaft. According to the results of finite element analysis, the hollow DCI crankshaft with reinforcing members turned out to be more reliable and superior than conventional one in terms of maximum stress and fatigue safety factor. Therefore, for heavy duty engines, the new concept of hollow DCI crankshaft with reinforcement realized by joining two different metals is highly recommended for engine builders to adopt in order to achieve cost reduction, short delivery and performance as reliable as the conventional ones at the same time.