US 11,697,173 B2
Systems and methods for friction bit joining
Michael P. Miles, Springville, UT (US); Rodney Dale Fleck, Draper, UT (US); Russell J. Steel, Salem, UT (US); Kevin Alexander Shirley, Provo, UT (US); and Shane Forrest Wood, Taylorsville, UT (US)
Assigned to Brigham Young University, Provo, UT (US); and Mazak Corporation, Florence, KY (US)
Filed by Brigham Young University, Provo, UT (US); and Mazak Corporation, Florence, KY (US)
Filed on May 9, 2019, as Appl. No. 16/407,353.
Claims priority of provisional application 62/668,946, filed on May 9, 2018.
Prior Publication US 2019/0344380 A1, Nov. 14, 2019
Int. Cl. B23K 20/00 (2006.01); B23K 20/12 (2006.01)
CPC B23K 20/1255 (2013.01) 21 Claims
OG exemplary drawing
 
1. A tool for friction bit joining a workpiece material, the tool comprising:
a bit rotatable around a rotational axis, the bit having:
a pin having a frustoconical face and a face angle of greater than forty-five degrees between the frustoconical face and the rotational axis, the pin configured to friction stir the workpiece material and displace the workpiece material radially outward as the pin friction stirs the workpiece material;
a non-cutting tip protruding axially downward from the frustoconical face of the pin, the non-cutting tip having a maximum width perpendicular to the rotational axis;
a first curved transition between the non-cutting tip and the frustoconical face, wherein the first curved transition is curved along the rotational axis;
a top surface opposite the pin with at least one feature recessed in the top surface, the at least one feature configured to transmit torque to the bit to rotate the bit around the rotational axis;
a flat shoulder between the pin and the top surface, the flat shoulder configured to contain workpiece material displaced by the pin;
a cylindrical side surface of the pin extending upward from the frustoconical face;
a second curved transition between the cylindrical side surface of the pin and the flat shoulder, the second curved transition configured to direct workpiece material displaced by the pin toward the flat shoulder wherein the second curved transition is curved along the rotational axis;
the frustoconical face tapering from a maximum outer diameter thereof at the cylindrical side surface to a minimum outer diameter thereof at the first curved transition; and
the maximum width of the non-cutting tip is less than half of a difference between the maximum outer diameter and the minimum outer diameter of the frustoconical face of the pin.