Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having structure to restrict rotation of threaded – mating... – Comprising a thread lock
Reexamination Certificate
1999-07-17
2001-02-20
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having structure to restrict rotation of threaded, mating...
Comprising a thread lock
C411S411000, C411S436000, C411S938000
Reexamination Certificate
active
06190101
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to threaded fasteners such as nuts and bolts and more particularly to threaded fasteners having an improved thread and reduced tolerances and improved fastening.
Threaded fasteners are well known to the art. One goal of threaded fasteners, particularly nut and bolt combinations, is to provide such a fastener that stays tightened and does not loosen in use. Generally accepted matching techniques result in tolerances between the nut an bolt threads and there is clearance or play which allows for movement between the elements. For example, a fastener or nut and bolt can loosen under load or vibration.
There are several prior art systems that try to remedy this problem. First, locknuts are used with a nylon washer locked in at the end of the nut. When the nylon washer contacts the bolt, it tightens around the thread and locks the nut in position. Locknuts have disadvantages. The nylon portion of nut has no load carrying threads. Further, it requires more material to make the nut longer and the nylon washer and the nut must be made separately and then crimped together. The locknut of this type can be used only a few times, is not as resistant to heat and requires chemicals i.e. nylon.
Deformed nuts have been used to overcome the loosening problem. These comprise nuts that are deformed out of the circular shape and made into rounded-off triangle shape. Then the bolt engages the threads, it contacts three points and the nut locks around the bolt. However, only heat-treated nuts can be used. To make the deliberate deformation requires an expensive manufacturing set-up. Further, the process is very slow. Also, the reaction of each individual nut is variable, which makes it difficult to predict or guarantee tolerances. Moreover, it can only be used with nuts.
A spiral lock is a lock thread is a commercially available alternative. However, the spiral lock provides an interference on the outside diameter of the bolt. It is difficult to control the interference with accuracy. The surface of the bolt thread can cause galling of the nut and subsequent failure.
Interference-fit threads are used which include a complete interference of the matching parts at the flanks to provide an interference or metal flow. However, based upon accepted machining practices, it is very difficult to produce, for example, class 5 threads (Federal Standard Screw-Thread Standards For Federal Services-Class 5 Interference Fit Screw Threads).
Examples of prior art fastener technologies are disclosed in the following U.S. patents: U.S. Pat. No. 1,369,156, to Woodward; No. 2,842,180, to Brown et al; No. 3,459,250 to Tabor; No. 3,661,194, MacFarlane et al.; No. 3,721,283, to Evan; No. 3,850,215, to Orlomoski; No. 3,927,503, to Wilson; No. 4,023,914, Holmes; No. 4,071,067, to Goldby; No. 4,396,321, Holmes; No. 4,846,614, to Steinbock; and No. 5,194,214, to Snyder et al.
It would be advantageous, therefore, to develop a fastener that has close tolerances yet is resistant to loosening or play without the disadvantages of the prior art designs.
SUMMARY OF THE INVENTION
It is among the principal objects of the present invention to provide a threaded fastener that is resistant to loosening.
It is another object of the present invention to provide a threaded fastener that has very close tolerances and is resistant to loosening.
Another object of the present invention to provide a threaded fastener that controls thread contact and tolerances along the thread pitchline.
Another object of the present invention to provide a threaded fastener that controls thread contact and tolerances along the thread pitchline and by controlling width of contact.
Still another object of the present invention is to provide such a threaded fastener that not only controls the pitch diameter of the respective threads to assure correct interference along the thread flank, but also controls the width of contact.
It is still another object of the present invention to provide such a threaded fastener that can be manufactured and produced in a broad range of sizes.
It is yet another object of the present invention to provide such a threaded fastener that is simple and economical to tool, versatile and well suited for its intended purposes.
In accordance with the invention, a threaded fastener is provided having a raised area or bump on the thread flank. The bump forces the mating threads at least on one flank to have near zero tolerances along the pitchline of the threads and thereby eliminating play.
REFERENCES:
patent: 1369156 (1921-02-01), Woodward
patent: 2842180 (1958-07-01), Brown et al.
patent: 3459250 (1969-08-01), Tabor
patent: 3517717 (1970-06-01), Orlomoski
patent: 3661194 (1972-05-01), Macfarlane et al.
patent: 3721283 (1973-03-01), Evans
patent: 3850215 (1974-11-01), Orlomoski
patent: 3927503 (1975-12-01), Wilson
patent: 4023914 (1977-05-01), Holmes
patent: 4071067 (1978-01-01), Goldby
patent: 4252168 (1981-02-01), Capuano
patent: 4396321 (1983-08-01), Holmes
patent: 4764067 (1988-08-01), Kawashima
patent: 4846614 (1989-07-01), Steinbock
patent: 5194214 (1993-03-01), Snyder et al.
patent: 5672037 (1997-09-01), Iwata
patent: 5944465 (1999-08-01), Janitzki
Denk Paul M.
Wilson Neill
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