Threadedly engageable coupling device

A threadedly engageable coupling device for use in a threadedly engaging tightening assembly which includes a complementary coupling device provided with a complementary threaded surface, and which is used for tightening first and second article pieces together, the first and second article pieces respectively having first tightened and abutment wall surfaces and second tightened and abutment wall surfaces opposite to each other, the first article piece being made from a material of a first hardness, and having a tubular bore that extends through the first abutment and tightened wall surfaces, said threadedly engageable coupling device comprising:

• an abutment head having an abutment wall which extends in radial directions, and which has a central area and an abutment peripheral area surrounding said central area;
• a cylindrical shank which extends from said central area along an axis, and which has a first outer diameter that is smaller than a caliber of the tubular bore, said cylindrical shank including proximate and distal segments relative to said central area, and a middle segment that is interposed between said proximate and distal segments, and that forms a juncture with said proximate segment, said distal segment having a primary threaded surface which is adapted to mesh with the complementary threaded surface, and being adapted to be moved relative to the complementary coupling device along the axis by a friction force that is generated through screwing movement of said primary threaded surface relative to the complementary threaded surface;
• and
• a plurality of blade portions which are disposed on said proximate segment, and which are angularly displaced from one another about the axis, each of said blade portions being made from a material of a second hardness that is greater than the first hardness, each of said blade portions extending from said proximate segment radially and outwardly, and terminating at a cutting edge, said cutting edge being configured to gradually deviate from said proximate segment as said cutting edge extends from said juncture towards said abutment wall such that when said cylindrical shank is inserted into the tubular bore from the first tightened wall surface to permit said abutment wall to be brought to abut against the first tightened wall surface by the friction force, said cutting edge incrementally incises the first article piece along the axis towards the first abutment wall surface so as to guard against rotation of said cylindrical shank relative to the first article piece during the screwing movement, thereby tightening the first and second article pieces together.