| 摘要 |
A bolt is required to have various functions such as a fastener for objects or a cover. For example, in the case such that a weight of the bolt is important; heat conductivity is important depending on the time. To satisfy the various requirements, the existing simple bolt made of a single material is redesigned to be the bolt made of a plurality of materials. The purpose of the present invention is to reduce the weight of the bolt by removing unnecessary elements. |
