Fasteners having threads formed of essentially helical coil structures
AssigneeWilliam P. Green
InventorMark Hattan
Life of this patent
Estimating the term…
Abstract
A threaded nut having a case containing a separately formed essentially helical coil structure which forms an internal thread and is fusion bonded to the case, preferably by electron beam welding. The coil structure desirably has a locking portion which is substantially free of direct attachment to the adjacent portion of the case, with this locking portion and the surrounding portion of the case both being deformed to a condition requiring radially outward displacement thereof upon threaded engagement with a mating screw, to thereby attain a very effective self-locking action preventing unscrewing the nut.
Claims21
A high strength composite lock nut comprising an essentially tubular case, and a separately formed coil structure contained within said case and having a hardened radially inner portion in work hardened condition shaped to form a thread, said coil structure having a plurality of turns with radially outer portions bonded directly to a surrounding portion of said case and softer than said inner thread portion, said coil structure having, at a location offset axially from said bonded turns, a locking portion which is within the case but not bonded to the portion thereof which is located directly radially outwardly of said locking portion, said locking portion being shaped to project radially inwardly farther than said bonded turns and inwardly far enough to have a self-locking action with a coacting screw and to require deformation of the self-locking portion radially outwardly upon threaded engagement with the screw, said portion of the case which is located directly radially outwardly of said locking portion of the coil structure having an inner surface extending approximately directly axially and engaged by an approximately directly axially extending external surface of said locking portion in a relation blocking said radially outward deformation of said locking portion and requiring slight radially outward deformation of the case itself at the location of said locking portion upon threaded engagement of said locking portion with said screw, so that the strength of the case is added to that of the locking portion of the coil structure for maximizing said locking action, said locking portion being fixed at its opposite ends against even slight relative movement of said ends in a direction to circularly elongate and thus radially constrict the locking portion.
A high strength composite lock nut comprising an essentially tubular outer case, helical coil means within said case forming an internal thread engageable with a coacting screw and having a first portion fusion bonded to a surrounding portion of the case, said coil means having a resilient locking portion at an end of said fusion bonded first portion which is free of direct attachment to the radially adjacent portion of the case and is shaped to a configuration which is not precisely helical and which requires deformation of said locking portion, when engaged by a coacting screw, in a relation increasing the radius of said locking portion at one location and decreasing its radius at another location, without a change in the length of the locking portion, and thereby attaining a self-locking action;
- said locking portion being fixed at its opposite ends against even slight relative movement of said ends circularly in a direction to circularly elongate and thus radially constrict the locking portion, to thereby avoid wraparound tightening of the locking portion on a screw upon relative rotation of the nut and screw.
A composite nut formed by the method that includes:
- positioning within a case a separately formed helical coil structure which is formed of metal in work-hardened condition and has a radially inner portion shaped to form an internal thread and a radially outer portion with an outer surface proximate the case;
- directing a high energy beam generally axially along the inner surface of said case and along said outer surface of the coil structure in a relation forming a fusion bond between said case and said radially outer portion of said coil structure;
- locally heating said radially outer portion of the coil structure by said high energy beam, during formation of said fusion bond, to a temperature locally adversely affecting the work-hardened condition of said radially outer portion;
- maintaining said internal thread formed by said inner portion of the coil structure in threaded engagement with an external thread on a highly heat conductive heat sink mandrel during said heating;
- and
- conducting heat away from said inner portion of the coil structure through the engaged threads of said heat sink mandrel during said heating and at a rate maintaining said inner portion of the coil structure at a temperature substantially lower than said radially outer portion, and low enough to prevent destruction of its thread shaped configuration, and to prevent as great an adverse effect if any on the work-hardened condition of said inner portion as on said outer portion, and thereby maintain said inner portion and the thread formed thereby substantially harder than said outer portion.
Dependencies are inferred from the claim text.