Patent ID: 6261040
Filing Date: 2001-07-17
Classification: B21K,F16B

Abstract:
A threaded fastener having a cross section, taken through an axis, that defines at least three lobes and three valleys therebetween, the lobes having a lobe maximum diameter with respect to the axis and the valleys having a valley maximum diameter with respect to the axis, the lobe maximum diameter being larger than the valley maximum diameter, and a relationship therebetween being defined by an out-of round dimension, the threaded fastener comprising:a main body section extending in an axial direction from a drive head toward a tip, the main body section having main body valleys with a main body valley maximum diameter and main body lobes with a main body lobe maximum diameter and defining therebetween a main body section out-of-round dimension;a tapered thread-forming section located forward, taken in the axial direction toward the tip, of the main body section, the tapered thread-forming section having, at each axial point therealong, tapered thread-forming section valleys with a tapered thread-forming valley maximum diameter and tapered thread-forming valley lobes with a tapered thread-forming lobe maximum diameter and defining therebetween a tapered thread-forming section out-of-round dimension, the main body section out-of round dimension being lower than the tapered thread-forming section out-of-round dimension; anda full-diameter thread-forming section located axially between the main body section and the tapered thread-forming section, the full diameter thread forming section having full-diameter thread-forming section valleys with a full-diameter thread-forming valley maximum diameter and full-diameter thread-forming valley lobes with a full-diameter thread-forming lobe maximum diameter and defining therebetween a full-diameter thread-forming section out-of-round dimension, wherein the full-diameter thread-forming lobe maximum diameter is approximately equal to the main body lobe maximum diameter and the full-diameter thread-forming out-of-round dimension is higher than the main body out-of-round dimension, whereby the lobes of the full-diameter thread-forming section exerts a higher thread-forming pressure than the lobes of the main body section.