| 摘要 |
The fastener is in a single piece and adapted to achieve the blind assembly and fixing of sumperimposed elements (A, B) provided with openings (C, D) which have a substantially square-shaped common part in which the fastener is engaged so as to fix together the element (A, B) after rotation of the fastener. For this purpose, it comprises a head (1) so shaped as to pass through the common part and connected to a rectangular-sided stem (3) so as to define two shoulders (4). This stem (3) is enlarged at one end in the form of a foot adapted to cooperate with the shoulders (4) by means of wings (6) of the foot to trap therebetween the elements (A, B). In order to achieve a positive locking, the fastener comprises two lock portions (10) disposed alongside and parallel to the stem (3) for the purpose of locking two branches (9) of the stem which are defined by a slot (8), against two opposed edges of the common part by spreading apart the branches (9) by penetration of a wedge-shaped portion of the lock portions (10) in the slot (8) in the course of the rotation of the fastener. By a positive locking of the assembly, the fastener prevents any vibration which would within time cause the shearing of the component parts of the fastener by maintaining the elements (A, B) in position. However, the latter are slidable relative to each other in any direction in the common plane of their contacting surfaces, as is for example required when the elements have different coefficients of expansion. |
