Patent ID: 8266782

Claim:
A joining method for joining a first member and a second member, wherein, using the first member which is a tubular member having an axially extended partition wall portion and a plurality of hollow portions partitioned by the partition wall portion and the second member having an insertion hole into which the first member is to be inserted, in a state in which the first member is inserted into the insertion hole of the second member, an expansion work of an inserted portion of the first member inserted in the insertion hole and both portions of the first member axially adjacent to the inserted portion is executed to thereby join the first member and the second member, characterized in that using a mandrel having a wedge portion divided into a plurality of wedge portion segments centering on the wedge portion, and a die having a wedge hole portion corresponding to the wedge portion of the mandrel and divided into a plurality of die segments in a circumferential direction centering on the wedge hole portion, in each hollow portion of the first member, the die segments of the die and the wedge portion segments of the mandrel are disposed, and then, in a state in which the partition wall portion is held by and between the wedge portion segments disposed in the two adjacent hollow portions via the partition wall portion of the first member, each wedge portion segment is simultaneously inserted into a wedge hole portion segment of the corresponding die segment to move each die segment radially outward of the first member to thereby execute the expansion work.