| 摘要 |
PCT No. PCT/NL92/00034 Sec. 371 Date Oct. 12, 1993 Sec. 102(e) Date Oct. 12, 1993 PCT Filed Feb. 18, 1992 PCT Pub. No. WO92/14566 PCT Pub. Date Sep. 3, 1992The invention concerns a method for riveting a packet (50) of sheets (51,52) by means of unannealed aluminum rivets made from an alloy harder than that of the relatively soft AD rivets in common use; this method is characterized by the fact that the expansion of the head to be formed at the shank end (58,59) of the rivet during the riveting process is controlled by a snap-tool (62) which encloses the shank end (58,59) at first loosely. When the expansion of the head diameter approaches D=1,5 d (with d the rivet diameter), i.e., the limit above which cracks form in the head, the tool (62) prevents further deformation and forces the material of the head to deflect towards the central portion of the rivet shank (57) which subsequently expands and widens the hole (53) sufficiently to make the riveted joint last considerably longer. The good loosely and, later in the process, tightly fitted enclosing of the shank end (58,59) by the snap-tool (62) allows the riveting to be done manually. This can still be improved further by using a snap-tool (62) with a profile (67, 68, 69) complementary to the contour of the shank end (58, 59). |
