| 摘要 |
PURPOSE:To make the promotion of lightweightness attainable as well as to improve productivity ever so high, by forming a plastic mode in advance, while casting a crankshaft bearing cap part by means of a full-mold foundry. CONSTITUTION:Each crankshaft bearing cap part is first formed with a plastic model 10. At this stage, each plastic model 10 is easily formable into complex form without any consideration of a die releasing direction. Therefore, this plastic model is easily formable into such a fog form as abstracting unnecessary thickness while keeping the strength required. This plastic model is replaced with a metal by means of a full-mold process so that the crankshaft bearing cap part 12 replaced with a substitution metal is unnecessary to consider a split mold in time of casting, thus productivity is raised so high and, what is more, it is formable into an optimum light weight structure. Since a horizontal beam 11 is also formed with a separate single part in advance, geometrical form machining is made performable, thereby constituting to improvements in the promotion of lightweightness and productivity. |
