Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having separate expander means – Frangible member
Reexamination Certificate
1999-09-10
2001-04-10
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having separate expander means
Frangible member
C411S034000, C411S069000
Reexamination Certificate
active
06213699
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to blind fasteners and more particularly to blind fasteners including a pin and a sleeve and having a mechanical lock structure for locking the pin and sleeve together and providing a hole fill of the openings of workpieces being secured together.
In many blind fastener applications it is desirable that the pin and sleeve be mechanically locked together to inhibit loosening, separation and/or loss of the pin through vibration, etc. Examples of such blind fasteners can be seen in the U.S. Pat. No. 4,863,325 for Two Piece Blind Fastener With Lock Spindle Construction Issued on Sep. 5, 1989 to Smith, U.S. Pat. No. 4,046,053 for Blind Rivet issued on Sep. 6, 1977 to Alvi et al, U.S. Pat. No. 3,288,016 for Blind Two-Piece Fastener issued on Nov. 29, 1966 to Reynolds, and U.S. Pat. No. 2,538,623 for Rivet Assembly issued on Jan. 16, 1951 to Keating.
It is also desirable in many applications to fill the workpiece openings. This is frequently done by radially expanding and compressing the shank of the sleeve against the surface of the workpiece openings by an expander portion of the pin. Various forms of such structures are also shown in the patents noted above.
BRIEF SUMMARY OF THE INVENTION
In the present invention a blind fastener, including a pin and a sleeve, is provided in which an internal portion of the sleeve is moved radially inwardly during installation by a portion of the pin into a lock pocket groove on the pin to form a primary lock holding the pin and sleeve together.
In addition, the pin has an elongated expander portion which operates with the portion of the sleeve shank in the workpiece openings to radially expand that sleeve portion to fill the workpiece openings. The sleeve shank portion is formed with a volume of material which in combination with the volume of the expander pin portion defines a volume greater than that required to fill the workpiece openings. At the same time, the expander pin portion is formed with a grooved section having plurality of axially extending, circumferentially disposed relief grooves separated by co-extensively extending expander segments located in a common circular plane. The relief grooves are adapted to receive the excess material of the sleeve shank portion after hole fill caused by the expander pin portion. The hole fill is caused primarily, by the expander segments and by a straight, circumferentially continuous, straight expander segment at the leading end of the expander grooved section. In this regard, the expander portion is provided to be of a length such that the relief grooves will extend partially past the inner or blind side workpiece surface of the workpieces to thereby provide additional volume to receive excess sleeve shank material. This provides an increased tolerance range for dimensional variations in the workpiece openings and related fastener while still providing a desired magnitude of compression of the expanded collar material against the workpiece openings over the increased tolerance range. In this regard an excess magnitude of compression cr an insufficient magnitude of compression could have an adverse affect on the installation, performance and/or strength of the fastener and fastened joint. For example an excessive volume could cause axial movement of the sleeve head away from engagement with the adjacent work piece surface resulting in an unsatisfactory, weakened joint. This type of occurrence is frequently referred to as “head rise”. This is inhibited by the present invention. In addition to providing the increased tolerance range noted, the relief grooves are also formed to provide an additional or secondary lock between the pin and sleeve by virtue of the sleeve material flowing into the relief grooves during hole fill. This increases the overall lock between the pin and sleeve.
At the same time the extra lock provides additional resistance to “pin bounce” and its adverse effects which can occur as a result of severing the pin tail or pull portion of the pin by fracturing of a breakneck groove.
In the present invention the expander portion of the pin has a generally circular cross-section. The relief grooves are generally shallow and are of a generally arcuate contour. The expander segments separating each of the grooves are in a circular plane of the overall circular contour of the expander portion with both the expander segments and grooves being wide and generally of the same circumferential width. As will be seen this structure enhances the expansion capability of the expander portion while substantially resisting distortion.
In addition, the unique structure of the expander portion also enhances the work hardening and hence strength of the expanded sleeve shank portion in the workpiece openings arid additionally provides significant work hardening and hence strength to the material of the workpieces at the workpiece openings which are subject to hole fill. This provides substantially improved static strength and fatigue life of the fastener, the workpieces and hence of the fastened joint.
Thus it is an object of the present invention to provide a novel two piece blind fastener, including a pin and a sleeve, and in which the pin and sleeve are adapted to provide hole fill of the workpiece openings and are mechanically locked together by material from the sleeve which is moved radially inwardly into a lock pocket in the pin and with an additional lock formed by the excess material from the expanded shank portion of the sleeve moved into relief grooves in the expander portion of the pin shank from hole fill.
It is still another object of the present invention to provide a novel two piece fastener, including a pin and a sleeve, and in which a shank portion of the sleeve is adapted to be radially expanded by the pin into compressive engagement with the workpiece openings and with the pin having a structure for expanding the sleeve shank portion and which is adapted to accept excess sleeve material from the compressive engagement in expansion whereby the fastener can be used to secure workpieces having an increase in the range of tolerance variations in the size of the workpiece openings.
It is a further object of the present invention to provide a novel two piece fastener, including a pin and a sleeve, and in which a shank portion of the sleeve is adapted to be radially expanded by an expander portion of the pin into compressive engagement with the workpiece openings and with the expander portion having a plurality of axially extending generally wide relief grooves circumferentially separated by relatively wide expander segments with the relief grooves adapted to accept excess sleeve material from the compressive engagement in expansion generally without distortion of the ridges whereby the fastener can be used to effectively secure workpieces having an increase in the range of tolerance variations in the size of the workpiece openings and fastener components while resulting in increased static strength and fatigue life of the fastened joint.
It is another object of the present invention to provide a novel, dual mechanical locking structure for the pin and sleeve of a two piece blind fastener and having an increased tolerance range for filling related workpiece openings.
It is a general object of the present invention to provide a new and improved two piece blind fastener.
REFERENCES:
patent: 2538623 (1951-01-01), Keating
patent: 3288016 (1966-11-01), Reynolds
patent: 3292482 (1966-12-01), Fry et al.
patent: 3298725 (1967-01-01), Boteler
patent: 3377907 (1968-04-01), Hurd
patent: 3390601 (1968-07-01), Summerlin
patent: 3515419 (1970-06-01), Baugh
patent: 3702088 (1972-11-01), Schmitt
patent: 4046053 (1977-09-01), Alvi et al.
patent: 4089249 (1978-05-01), Binns
patent: 4355934 (1982-10-01), Denham et al.
patent: 4405273 (1983-09-01), Ruhl et al.
patent: 4627775 (1986-12-01), Dixon
patent: 4639174 (1987-01-01), Denham et al.
patent: 4781500 (1988-11-01), Mauer
patent: 4789283 (1988-12-01), Crawford
patent: 4846611 (1989-07-01), Sadri et a
Hufnagl Gerhart
Parker, Jr. Lloyd
Sadri Shahriar M.
Harness & Dickey & Pierce P.L.C.
Huck International Inc.
Wilson Neill
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