Pull-type blind fastener construction

An improved pull-type blind fastener for use in securing a plurality of workpieces together, said fastener comprising:

• a sleeve having a preformed head provided on one end thereof;
• a mandrel positioned for longitudinal movement within said sleeve to form a head on the other end of said sleeve, said mandrel having an annular lock pocket provided thereon and another portion of a predetermined diameter operative to expand said sleeve;
• an opening defining an inwardly directed entry resistance portion provided in said sleeve head;
• an annular locking collar positioned in part within said opening and having a bore through which said mandrel projects, said locking collar being adapted to be moved inwardly along said entry resistance portion into engagement with said lock pocket of said mandrel by action of an end portion of an installation tool nose assembly engaging said locking collar as said fastener is set, said nose assembly having an opening of a diameter only slightly greater than said predetermined diameter into which said mandrel projects, said bore of said locking collar being defined by an inner portion of a diameter less than said predetermined diameter and an outer portion of a diameter greater than said predetermined diameter, said outer portion being engageable with said tool end portion in a radially offset relationship relative to said nose assembly opening, said outer portion thereby defining a recess in said collar adjacent said opening into which material from said inner portion may be wiped by said mandrel as it is moved through said collar by action of said pulling tool whereby said predetermined diameter portion may be moved through said locking collar and said locking collar may be moved into said opening without formation of collar flash.

An improved pull-type blind fastener for use in securing a plurality of workpieces together, said fastener comprising:

• a sleeve having a preformed head on one end thereof, an elongated tubular body portion and a bore extending therethrough,
• an elongated mandrel extending movably through said sleeve and having a head provided on another end thereof, said mandrel head being operative to form a head on another end of said tubular sleeve in response to a pulling action exerted on said mandrel by an installation tool, said mandrel further having a lock pocket provided thereon,
• a straight wall counterbore provided in said head terminating at an entry resistance angle;
• and
• an annular locking collar positioned partially within said counterbore and having a bore through which said mandrel extends, said locking collar having an end portion engageable by a nose assembly of said installation tool whereby said locking collar is operative to enable said pulling tool to exert a pulling force between said mandrel and said sleeve, said bore having a first portion of a substantially constant diameter extending axially inwardly from said terminal end and radially spaced from said mandrel and a second portion of a substantially constant diameter less than the diameter of said first portion and engageable with a portion of said mandrel as said mandrel is moved through said collar, said first portion defining an annular recess within said collar into which material from said second portion may be wiped by said mandrel whereby said locking collar is operative to reduce the possibility of formation of collar flash during setting of said fastener.