Patent ID: 8579180

Claim:
A mandrel tool probe for performing a friction-stir process, the probe comprising: a shank having a cylindrical shape; and a tip coupled to the shank and free of threads, the shank and tip being concentric and rotatable about a given axis, the tip having a cross-section that defines an inscribing circle with a core diameter, and a concentric circumscribing circle with a swept diameter greater than the core diameter, wherein the tip includes a set of a plurality of physically-separate, spiraled surfaces separated by land areas between adjacent spiraled surfaces, each of the spiraled surfaces and land areas extending along a length of the tip at a spiral angle around the circumference of the tip, wherein the tip has a cross-section with a constant shape along the length of the tip, the cross-section of the tip including a plurality of major segments interconnected via minor segments, each of the major segments being formed of a respective spiraled surface, and each of the minor segments being formed of a respective land area and having a length that is less than 10% of the length of each of the major segments, and wherein each major segment is linear or deviates from linear with a height at its apex of no more than half the distance from the core diameter to the swept diameter, a chord of the circumscribing circle that shares endpoints with the major segment being tangent to the inscribing circle.