| 摘要 |
PROBLEM TO BE SOLVED: To insert a key while positioning it with oppositely arranged projections by providing positioning projections for a key in the vicinity of the opening edge of a hole, at the opposite sides of the hole. SOLUTION: A hole 24 is constituted of long sides 27, 27, short sides 28, 28 formed at fight angles against the long sides 27, round corners 29 formed at the four corners where the long side 27 and the short side 28 cross each other, projections 31 formed at the center of the long sides 27, projections 32 formed parallelly to the projections 31, and projections 33 formed at the center of the short sides 28. A key 40 is brought into contact with the projection 33 when it is shifted to the right or left side by forming small the distance between the projections 33 and the key 40 in the state the key 40 is inserted in the hole 24. And hence, the key 40 can be stopped at a specified position. In this way, when the key is inserted while being positioned, the key slides while the projections 31 come into contact with the inner grooves 41 of the key 40 and further, the projections 32 slide in a groove 42 to guide the key 40. |
