| 摘要 |
<p>A mandrel (15) inserted in a rivet body (11) to form a blind rivet (10) has a head (17) extending from a rod-shaped mandrel body (16). The head (17) is formed to have a plane top surface (18) perpendicular to the mandrel body, has a diameter 'D' almost equal to the outer diameter of rivet body, and a height 'H' of 80% - 120% of the mandrel body's diameter 'd'. A frustum-shaped low protrusion (19) formed centrally of and on the top surface has an upper surface (20) of a diameter 'd1' slightly greater than the diameter 'd'. A conical or otherwise curved surface (21) of the mandrel head applies a force to an open end (11a) of the rivet body (11) in a self-centering manner when force is imparted to the mandrel body (16) to caulk or deform the open end (11a), so that a uniform caulking is effected, with the head being retained not to slip off the caulked rivet body (11) whose length is noticeably reduced. Apparatus is also disclosed which, if installed in a nailery machine, enables the easy production of the mandrel (15) in the same manner as the prior art mandrels. <IMAGE></p> |
