| 摘要 |
An improved fastener assembly is designed for securing a workpiece, having known thickness and a hole therethrough and being subject to plastic deformation, to a support. The fastener assembly can apply a high clamping load to the workpiece yet causes minimal cold plastic deformation of it and includes a fastener having a head and a shank projecting from the head. The shank includes an upper portion adjacent the head, an annular rib that protrudes radially outwardly from the upper portion at its extreme opposite the head, and an operative portion engageable in the support. A washer having a hole therein is received about the upper portion of the shank and is formed on one of its faces with an annular rabbet encircling the hole. A sleeve includes a generally cylindrical side wall having an axially extending split discontinuity and circular edges at its opposing axial extremes. The sleeve also includes a constriction at one of the circular edges, having a reduced diametrical dimension, that is confinable between the rib and the bearing surface of the head of the fastener. In the normal condition of the sleeve with its cylindrical side wall collapsed at the discontinuity, the one edge of the side wall is received in the annular rabbet of the washer to confine the side wall from spreading at the discontinuity. When the fastener device is engaged in the support the sleeve bears the major portion of the clamping load while the washer holds the workpiece in place against the support.
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