BOLT ASSEMBLY AND CARBURIZATION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a bolt assembly and a carburization method therefor that perform carburization on a seating face in which seating surface strength is requested while preventing carburization on a bolt hole having a female screw part formed.SOLUTION: A seating face 35 is formed at a first division member 22 between the first division member 22 and a second division member 23 fixed with a fixing bolt, and a female screw part 39 is formed on an internal surface of a bolt hole 38 of the other second division member 23. The first division member 22 has a tapered surface 41 formed to be inclined or curved in a conic shape to decrease in diameter from the seating face 35 to a bolt hole 36. In a carburization process, an inclined surface part 47 of a tool 43 for carburization is seated on the tapered surface 41 without abutting on the seating face 35 so as to close the bolt holes 36, 38.SELECTED DRAWING: Figure 4