| 摘要 |
Structural joint for joining two elements (12, 14), the first element (12) having an elongate major tongue (22) of malleable deformable material and in one embodiment an elongate minor tongue (24), the second element (14) having an elongate protuberance in the form of e.g. curled tab (36). The major and minor tongues define an elongate recess adapted to receive the curled tab on joint formation. The major tongue (22) is deformed about the curled tab (36) to form at least a portion of an encircling curl which contacts the curled tab's external surface. When the elements are so joined, the gap between the major and minor tongues is less than the width of the curled tab, thereby precluding removal of the curled tab from the encircling curl. Prior to joint formation, the curled tab (36) is curled about a wire (37) which acts as a filler or support, and the joint will therefore be tight and solid. The inventive structural joint can preferably be used in ladders having rungs secured to side rails. |
