| 摘要 |
A raw parallelepiped metal piece is pressed into a closed mold to provide a nut blank that has a generally square pilot portion (14) for piercing a metal panel, the nut blank having a pair of flanges (16) that continue from opposite side walls (15) of the pilot portion. Then, the nut blank is coined to form ridges (20) extending along and integral with opposite upper edges of the side walls (15), before pressed within an open mold so that the ridges are swaged out sideways to form shoulders (21). A lateral groove (22) is defined between below each shoulder and in the side wall. A rough bore (23) will be formed axially through the pilot portion (14), before tapped to have a female thread (24) in the inner periphery of the bore. <IMAGE> |
