| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate a concern that water remains in a thickness reducing recess for shrinkage prevention. SOLUTION: A drain hole 16 is formed at the bottom of a thickness reducing recess 15 of a boss part 9. As a result, the concern that water remains in the recess 15 is eliminated by virtue of the drain hole 16 because the water in the recess 15 is drained outside from the drain hole 16 at the bottom of the recess 15 even if the recess 15 for shrinkage prevention is formed in the boss part 9 in which a stud bolt 10 is embedded and the opening of the recess 15 faces almost upward.</p> |
