Method and apparatus for joining the plates by punching-stressed.

An upsetting process for bonding a first plate (10) having a tapered through hole (11) tapers towards a side surface of the first plate and defined by a surface bevel (13) and an area swaging hollow cylindrical (12) extending from a periphery of the tapered hole on one side surface of the first plate and having a through hole and a second plate (20) having a bore (21), the upsetting process comprising: inserting the area of ​​hollow cylindrical swaging (12) of the first plate (10) through the bore (21) of the second plate (20) for projecting a zone of the tip end area of ​​hollow cylindrical swaging (12 ) beyond the bore (21) and overlaying the second plate (20) on the first plate (10); and bending back of the area of ​​the tip end area of ​​hollow cylindrical swaging (12) of the first plate (10) on a periphery of the hole (21) of the second plate (20) on a side surface of the second plate (20), while pressing against the surface bevel (13) of the first plate (10) so as to prevent the area of ​​hollow cylindrical swaging (12) to flow to the other side of the surface of the first plate (10) along the periphery of the tapered through hole (11).