| 摘要 |
A lug-and-hole connection between a first, lug-bearing sheet metal element and a second, apertured sheet metal element is made by so forming the hole in the first element that it is bounded by out-turned, opposite, convergent wall portions spaced apart, at the narrowest distance between them, by a distance slightly less than the lug thickness. The hole is made without removing material from the first element, as by forcing through it the wedge-shaped tip of a chisel-like punch while backing that element with a flat-topped die having cylindrical cavity. After the lug is inserted into the hole, a tip portion of the lug, which projects beyond the wall portions, is swaged to form it into a rivet-like head that snugly overlies the outer edges of the wall portions, but the wall portions are not reworked in the head forming operation. |
