FASTENER WITH MULTILOBULAR TOOL ENGAGING PORTION

摘要

A fastener comprising a fastener body 2 and a fastener head 4 is disclosed. The fastener body 2 has a threaded portion and defines a longitudinal axis 3. The fastener head 4 is arranged at one end of the fastener body 2, and comprises a tool engaging portion. The tool engaging portion 5 comprises a plurality of alternating lobes 7 and flutes 8 forming a multilobular surface pattern, each lobe 7 having a driven surface 9 arranged to engage with a driving surface of a tool, and a trailing surface 10 arranged opposite to the driven surface. The driven surface 9 and the trailing surface 10 extend substantially parallel to the longitudinal axis 3 defined by the fastener body. The trailing surface 10 of at least one lobe 7 is provided with a modified zone in which a diameter of the lobe 7 is increased, said modified zone providing a wedging effect between the tool engaging portion and a tool.