Abstract: A system for attaching layers of material together comprised of a self-piercing rivet, a layer having a clearance hole through which the self-piercing rivet passes on assembly, and a layer free of a clearance hole and into which the self-piercing rivet is at least partially inserted. The system may include a third layer free of a clearance hole. The system may also include three layers wherein the clearance hole is formed in the middle layer. If the clearance hole is formed in the middle layer, the width of the hole may be greater than the diameter of the self-piercing rivet to avoid contact between the rivet and the middle layer. The layer having the clearance hole may be a hard material such as steel. One or more of the layers may be material that is difficult to pierce or can be damaged if pierced.

Abstract: A rivet nail for forming a nailed joint to join parts together. The nail has a shank with a longitudinally-extending opening formed therein in the shape of a rhomb defined by two congruent triangles with an imaginary common base line. The widest portion of the opening is defined by the base line. The length of the opening is at least three times as long as the largest width of the shank, and the length of the shank between the end of the nail and the opening is at least one-fourth as long as the length of the opening.

Abstract: A pair of nail shank pieces are united face to face through the intermediary of a strip metal, and the tip parts of both nail shank pieces are tapered so that both nail shank pieces may be gradually opened as the nail is driven in. The metal strip is subjected to a compressive deformation to support the nail shank pieces from inside, thereby helping in their maintaining an opened state. Both nail shank pieces engage the base material in a dovetail fashion and in this way, the countering force against the nail's coming out is reinforced. A clamping ring fit around the outer circumference of both nail shank pieces to hold the metal strip therebetween such that both nail shank pieces are prevented from opening at the base material surface, and moreover, the opening made by the nail at the base material surface is protected from widening, while aiding in both nail shank pieces entering deep into the base material.

Abstract: A fastening element assembly consists of an anchoring bolt and a spreading wedge. After the assembly is inserted into a prepared borehole, by driving the spreading wedge inwardly relative to the anchoring bolt, the bolt is secured in the borehole. To ensure that it is driven into the borehole for a sufficient distance, the spreading wedge is provided with a separating web intermediate its ends so that if a predetermined breaking point of the separating web is reached, the web breaks and the rear part of the wedge can be driven into the borehole relative to the forward part.