Lightweight fastener
First Claim
1. A threaded fastener comprising:
- a head;
a cylindrical shank;
a tip having a roll formed thread with a uniform pitch P, a major diameter which is less than the shank diameter, and a minor diameter;
a maximum grip plane defined between the shank and tip a specified length from the head; and
a run-out zone between the maximum grip plane and the tip having a length in the range of from 1.58P to 2.3P, the run-out zone having a roll formed thread, the thread root in the run-out zone being tangent to the minor diameter at one end and enlarging toward the maximum grip plane along a continuous outwardly concave curve to at least a portion near the maximum grip plane.
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0 Petitions
Accused Products
Abstract
An aerospace fastener comprises a bolt with a roll-formed thread, and a nut with a similar thread having a uniform pitch P. The bolt has a cylindrical shank, a threaded tip and a run-out zone between the shank and tip. The thread root in the run-out follows a concave curve having a radius in the range of from 2.0P to 2.7P and extends 1.58P to 1.8P from the maximum grip plane of the bolt. The nut has a convexly curved run-in truncating the crest of the nut thread complementary to the run-out to clear the root of the bolt thread when the nut is assembled on the bolt in the minimum grip condition. This permits the nut to be assembled on the bolt further than in a conventional combination, and shortening of the nut and bolt by at least 1P to save weight.
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Citations
51 Claims
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1. A threaded fastener comprising:
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a head; a cylindrical shank; a tip having a roll formed thread with a uniform pitch P, a major diameter which is less than the shank diameter, and a minor diameter; a maximum grip plane defined between the shank and tip a specified length from the head; and a run-out zone between the maximum grip plane and the tip having a length in the range of from 1.58P to 2.3P, the run-out zone having a roll formed thread, the thread root in the run-out zone being tangent to the minor diameter at one end and enlarging toward the maximum grip plane along a continuous outwardly concave curve to at least a portion near the maximum grip plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A threaded fastener comprising:
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a head; a cylindrical shank; a tip having a roll formed thread with a uniform pitch P, a major diameter which is less than the shank diameter, and a major diameter; a maximum grip plane defined between the shank and tip a specified length from the head; and a run-out zone between the maximum grip plane and the tip having a roll formed thread, the thread root being tangent to the major diameter at one end and enlarging toward the maximum grip plane along an outwardly concave curve having a radius in the range of from 2.0P to 2.7P. - View Dependent Claims (11, 12, 13)
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14. A threaded fastener comprising:
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a body a threaded hole in the body; a thread having a uniform pitch P in the hole; a counterbore at one end of the hole having an inside diameter larger than the diameter of the thread root and a length less than 1/16 inch plus 0.5P; and an inwardly convex curved run-in extending into the thread from the counterbore and truncating the crest of the thread, the run-in having a relatively larger diameter at the end of the counterbore, and a relatively smaller diameter at a distance of at least 1.8P from the end of the counterbore substantially tangent to the crests of the thread of the fastener. - View Dependent Claims (15, 16, 17)
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18. A threaded fastener comprising:
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a body; a threaded hole in the body; a thread having a uniform pitch P in the hole; a counterbore at one end of the hole having an inside diameter larger than the diameter of the thread root and a length less than 1/16 inch plus 0.5P; and a run-in extending into the thread from the counterbore and truncating the crest of the thread, the run-in having a relatively larger diameter at the end of the counterbore, and a relatively smaller diameter substantially tangent to the crests of the thread of the fastener, the run-in truncation following an inwardly convex curve having a radius in the range of from 1.7P to 2.7P. - View Dependent Claims (19)
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20. A threaded fastener comprising:
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a bolt having a head, a cylindrical shank adjacent to the head, a tip having a roll formed thread with a uniform pitch P, a maximum grip plane defined between the shank and tip a specified length from the head, and a run-out zone between the maximum grip plane and the tip, the run-out zone having a roll formed thread with the thread root being tangent to the minor diameter of the thread on the tip and enlarging toward the maximum grip plane along an outwardly concave curve; and a nut having a hole with a thread of uniform pitch P, a counter bore in the end of the nut nearer the head of the bolt with an inside diameter larger than the diameter of the shank, and a run-in truncating the crest of the thread along an inwardly convex curve, the length of the run-in from the maximum grip plane when the nut is threaded on the bolt to a minimum grip position being at least as long as the length of the run-out zone from the maximum grip plane, so that the run-in the nut overlaps at least a portion of the run-out on the bolt and the truncated portion of the nut thread clears the bolt thread root in the run-out. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A threaded fastener comprising:
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a bolt having a cylindrical shank, a tip having a roll formed thread with a uniform pitch P and a thread run-out zone between the thread on the tip and the shank, the run-out having a roll formed thread wherein the root of the thread follows a gradually enlarging path from tangency with the root of the thread on the tip toward the shank, the incomplete thread in the run-out being at least partly completely formed at diameters greater than the thread root in the run-out; and a nut having a hole with a thread of uniform pitch P and a run-in truncating the crest of the nut thread toward the end of the nut, the incomplete nut thread in the run-in engaging a - completely formed portion of the thread in the run-out on the bolt and the truncation of the nut thread clearing the incomplete thread root in the run-out when the nut is threaded onto the bolt with the run-in overlapping the run-out. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41)
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42. A method for making a threaded fastener having a head, a cylindrical shank adjacent to the head and having a specified length to a maximum grip plane, and a threaded tip beyond the maximum grip plane comprising:
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forming a fastener blank with a head, a cylindrical shank, a cylindrical tip having a diameter substantially the same as the pitch diameter of the thread, and a run-out zone between the tip and the shank, the run-out zone having a continuous concave curve from a location tangent to the tip diameter to at least the major diameter of the thread; and rolling the blank between ridged thread forming dies, each of the dies having a run-out chamfer along an edge, the run-out chamfer having a continuous convex curve from the edge to the crests of the thread forming ridges at the same distance from the edge as the distance between the maximum grip plane of the bolt and the location where the run-out zone is tangent to the tip diameter. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51)
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Specification