Friction stir nut and method of joining therewith
View Patent ↗A friction stir nut is disclosed. The friction stir nut includes a body, a cap, and an anti-rotation feature. The body has an elongated cylindrical shank extending between a first end and a second end, the cap being disposed at the second end, and the anti-rotation feature being disposed at the cap and/or an outer surface of the body. The body and cap have a blind axial hole extending from the first end to the second end, the first end being blind and the second end being open. The outer surface of the first end has a flat surface oriented substantially perpendicular to the axis of the shank, and the body has a cylindrical wall thickness suitable for receiving internal threads. In response to a mandrel tool friction stir welding the friction stir nut to a workpiece and then being extracted, uniform internal threads result at the body. The anti-rotation feature bonds to the workpiece by metallurgical bonding and/or mechanical bonding.
1. A friction stir rivet nut in combination with a workpiece, the combination comprising:
a workpiece and a friction stir rivet nut, the friction stir rivet nut comprising a material capable of being friction stir welded to the workpiece via a mandrel tool, the friction stir rivet nut further comprising:
a body having an elongated cylindrical shank extending between a first end and a second end, the body comprising a first portion proximate the first end and a second portion proximate the second end, the first portion having a first nominal cylindrical wall thickness, the second portion having a second nominal cylindrical wall thickness that is less than the first nominal cylindrical wall thickness;
a cap at the second end; and
an anti-rotation feature at the cap, at an outer surface of the body, or at both, the anti-rotation feature comprising a void in material forming the friction stir rivet nut;
wherein the body and cap have a blind axial hole extending from the first end to the second end, the first end being blind and the second end being open, the first end having uniform internal threads, the outer end surface of the first end having a flat surface oriented substantially perpendicular to an axis of rotation of the shank;
wherein the anti-rotation feature of the friction stir rivet nut is metallurgically and mechanically bonded to the workpiece;
wherein a metallurgically bonded region between the friction stir rivet nut and the workpiece comprises plasticized material of the workpiece.
2. The combination of claim 1 , wherein:
a mechanically bonded region between the friction stir rivet nut and the workpiece is defined in response to the mandrel tool friction stir welding the friction stir rivet nut to the workpiece and then the mandrel tool being pulled, thereby causing the second portion of the body to buckle at an opposite side of the workpiece to that of the cap.
3. The combination of claim 2 , wherein:
in response to the mandrel tool friction stir welding the friction stir rivet nut to the workpiece and then the mandrel tool being rotationally extracted from the friction stir rivet nut, the uniform internal threads remain at the body.
4. The combination of claim 1 , wherein:
the anti-rotation feature comprises at least one of a recess profile, a scallop profile, and a hole profile.
5. The combination of claim 1 , wherein:
the anti-rotation feature at the cap comprises at least one of a scalloped section profile at a perimeter of the cap, a recess profile at an underside of the cap, and a through-hole profile at the cap.
6. The combination of claim 1 , wherein:
the anti-rotation feature at an outer surface of the body comprises a recess profile, a projection profile, or both.
7. The combination of claim 1 , wherein:
the body and cap comprise iron.
8. The combination of claim 1 , wherein:
the body and cap comprise a material having a higher melting point than that of a material of the workpiece.
9. The combination of claim 1 , wherein:
the flat surface oriented substantially perpendicular to the axis of the shank is perpendicular to within plus-or-minus two degrees thereof.
10. The combination of claim 9 , wherein:
the flat surface has a diameter equal to or greater than about 80% of the outside diameter of the first end of the body.
11. The combination of claim 1 , wherein the metallurgically bonded region comprises material of the workpiece intermingled with material of the friction stir rivet nut.
12. A friction stir rivet nut in combination with a workpiece, the combination comprising:
a workpiece and a friction stir rivet nut, the friction stir rivet nut comprising a material capable of being friction stir welded to the workpiece via a mandrel tool, the friction stir rivet nut further comprising a body, and a cap disposed at one end of the body, the cap comprising an anti-rotation feature comprising at least one of a recess profile, a scallop profile, and a hole profile;
wherein the friction stir rivet nut is metallurgically and mechanically bonded to the workpiece, and wherein the anti-rotation feature is metallurgically and mechanically bonded to the workpiece;
wherein a metallurgically bonded region between the friction stir rivet nut and the workpiece comprises plasticized material of the workpiece.
13. The combination of claim 12 , wherein:
a mechanically bonded region between the friction stir rivet nut and the workpiece comprises a portion of the workpiece being in compression between a cap portion of the friction stir rivet nut on one side of the workpiece and a buckled portion of the friction stir rivet nut on an opposite side of the workpiece.
14. The combination of claim 11 , wherein the metallurgically bonded region comprises material of the workpiece intermingled with material of the friction stir rivet nut.