Importance

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Abstract

An elongated stem extends through a bore in a sleeve having a preformed head at one end. The sleeve extends through aligned holes in one or more workpieces to be fastened together. Pulling the stem through the sleeve causes an enlarged tail on the stem to be drawn into the end of the sleeve opposite the preformed head. The sleeve thus expands, forming a blind head. The workpieces are sandwiched between the preformed head and the blind head. To prevent the stem from sliding out of the sleeve, a locking collar is provided within the sleeve bore. The collar is slideable from a first position spaced from the preformed head to a second position within the preformed head. The collar is engaged by a shoulder on the stem and is moved from the first position to the second position as the stem is pulled through the sleeve. When in the second position, the collar is prevented from further movement, and is deformed as the stem continues to advance. The deformed collar fills an annular lock pocket within the preformed head and an annular locking groove surrounding the stem, thus preventing movement of the stem relative to the sleeve. The collar is formed from the sleeve material and is positioned within the sleeve prior to the insertion of the stem. In the manufacture of the sleeve, a reduced diameter bore portion is formed. An annular portion of the sleeve material surrounding the reduced diameter bore portion is separated from the remainder of the sleeve in a shearing operation, thus forming the collar.

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First Claim