DISPOSITIF DE FIXATION AVEUGLE

A blind fastening element for fastening a workpiece which is provided with an opening and consists of fragile material, for example composite material, comprises a nut (12), a bolt (14) provided with a head, and an expandable tubular sleeve (16). The nut (12) is a tubular body which has a pin (18) with a head (20) at one end and a chamfered nose (22) at the other end. A blind head via which a workpiece can be firmly clamped on the head (20) may be designed in that the bolt (14) is screwed into the nut (12), with the result that the head (32) of the bolt (14) forces a part of the sleeve (16) over the nose (22) by means of a leading end (60). The angle of the chamfer of the nose (22) is sufficiently steep, at least in the region beside the pin (18), to expand a part of the sleeve (60) to an inner diameter which is greater than the diameter of the pin. The sleeve (16) is cylindrical and has a stepped bore (40) with a shoulder (66). A portion (68) of the sleeve (16) near the end (60) has a greater inner diameter and a thinner wall than a portion (70) beyond the shoulder (66). The length and the inner diameter of the portion (68) are such that the nose (22), when coming in contact with the sleeve (16) at the end (60), does not come into engagement with the portion (68) but with the portion (70) at the shoulder. When the nose (22) ... the thick-walled ... Original abstract incomplete.