Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Threaded fastener locked to a discreet structure – Nut – and means to engage substructure on its opposite faces...
Reexamination Certificate
2000-06-07
2001-10-23
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Threaded fastener locked to a discreet structure
Nut, and means to engage substructure on its opposite faces...
C411S183000, C411S427000
Reexamination Certificate
active
06305888
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to T-Nut fasteners of the type having a generally tubular barrel, at least a portion of which is formed with an interior female thread, and having generally planar flanges extending generally normal to the axis of the barrel, at one end, and in particular to such a T-Nut which is formed with scalloped edges along opposite ends of the flanges, to ensure smooth feeding in a fastener feed track.
BACKGROUND OF THE INVENTION
T-Nut fasteners consisting of a tubular barrel and a generally peripheral flange at one end, are well known. They are particularly useful in the furniture industry. In this case they are embedded into a work piece typically an element of a piece of furniture which may be made of wood or composition or in fact thermo-plastic in some cases. When the furniture is assembled, bolts or other threaded fastening devices are inserted into the T-Nuts to hold two components of furniture together. Any one piece of furniture may incorporate a large number of T-Nuts, and it will be readily understood that the use of such T-Nuts is wide-spread and on a very large scale. Such T-Nuts are formed by stamping them out of sheet metal, so that the barrel is extruded from the plane of the sheet, and the flanges are cut out from the sheet, so as to form an integral one piece sheet metal T-Nut. The barrel is usually internally female threaded either along its whole length or along a portion of its length. In some cases the free end of the barrel may be provided without threads so that it can be swaged or flared out to provide as it were a rivet action, holding the T-Nut in the work piece. Such T-Nuts are in a great majority of cases provided with spikes, usually four spikes, which are formed by cutting edges of the flanges, to form a series of pointed spikes or prongs which are then bent usually at right angles to the plane of the flange. These prongs embed in the workpiece and provide further security to hold the T-Nut in position.
All these facts are very well known in the industry and are merely repeated here for the sake of clarity and explanation. Numerous patents show various forms of T-Nuts, some of which are listed at the end of this description.
From this explanation it will be understood that the insertion and securing of the T-Nuts in the work piece must be carried out at high speed and with great accuracy and repeatability. Numerous machines have been developed for this purpose to provide automatic power insertion of T-Nuts into a work piece. Many of these machines also provide the swaging or flaring action to flare the free end of the barrel.
Usually such T-Nuts are packaged loose in large containers. They are dumped from these containers into feed hoppers on the insertion machines. They are delivered usually along a feed slide extending from the hopper to the insertion anvil or hammer which drives the T-Nut into the work piece.
It will be understood that continuity and repeatability of operation in such a machine are absolutely essential to provide smooth flow of production of finished product. If there is any holdup in such a machine it may slow down production for minutes or even hours while the machine is made serviceable once more. This downtime causes loss of production, frustration in employees, and may cause missed delivery dates.
One of the leading causes of problems in such machines is that the edge flanges of the T-Nuts, being stamped out from sheet metal, are formed with minute burrs at various points. These burrs become more aggravated as the stamping dies become worn.
The edges of the flanges are sharp, and in most cases are formed in a linear fashion. In many cases the flanges are octagonal. In other cases, they are simply round.
All such flanges do experience certain problems in achieving a smooth flow of T-Nuts along the feed slide, and stoppages are experienced in a random fashion when using insertion machines with such T-Nuts.
One of the problems in such feed slides is that they are usually formed around a curved path. There must therefore be a certain amount of clearance within the slide, to allow for the planar flange to pass around a curved path. There is often a tendency for the flange of one T-Nut to ride up over the flange of a leading or trailing T-Nut, and this then causes jamming of the T-Nuts in the slide and malfunction of the machine.
One approach to overcoming this problem is shown in U.S. Pat. No. 4,508,478, entitled T-Nut Fastener Member, inventor: Herbert E. Leistner, Toronto, Canada, granted Apr. 2, 1985.
In this T-Nut, the leading and trailing flange edges are formed with a generally U-shaped depression. The U-shaped depressions of adjacent T-Nuts function to prevent the over-riding of the flange of one T-Nut with the next, in the slide.
While this improved T-Nut greatly reduces the problem, it has been found desirable to provide still further enhancements. This will be of significance where the T-Nuts are going around a track which exhibits a compound curve. In these cases the T-Nuts may have a tendency to twist slightly from side to side. As a result of this twisting one T-Nut flange may still on occasion jam with the next T-Nut flange. While this occurrence is relatively rare, it will be appreciated from the above explanation that any malfunction of the insertion machine is undesirable.
BRIEF SUMMARY OF THE INVENTION
With a view therefore to providing a T-Nut with still greater resistance to slide jamming, the invention comprises a T-Nut of the type having a generally tubular barrel with an interior female thread along at least a portion of the barrel, and a flange at one end of the barrel extending substantially normal, prongs formed integrally with the flange, and bent at an angle thereto to embed in a work piece, and wherein the flange is formed with planar side portions adapted to ride in a feed slide mechanism, and having substantially linear side edges parallel to one another in spaced apart relation, to guide the T-Nut along the slide mechanism, and having end edges on the flange, at the leading and trailing edges of the flange, which end edges are adapted to abut with respective end edges on leading and trailing T-Nuts within the feed slide mechanism, a generally median U-shaped depression formed in each of said leading and trailing edges of said flange, and, generally arcuate recesses formed in each of said edge flanges, on either side of said U-shaped depression, whereby to provide a generally scalloped edge, along each of said leading and trailing edges of said flange.
The invention further provides such a T-Nut wherein the barrel comprises a first female threaded portion, extending from said flange, and a second flarable portion, having an outer diameter greater than the outer diameter of said first threaded portion, extending from said first threaded portion to the free end of said barrel.
The invention further provides that at the free end of said flarable portion, a generally radius in-turned mouth is formed, to facilitate insertion into a work piece.
The invention further provides that the edge flange is formed with integral prongs, extending alongside the tubular barrel, and in which the prongs are formed with generally saw tooth like serrations.
The various features of novelty which characterize the invention are pointed out with more particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 5348432 (1994-09-01), Nagayama
patent: 5863164 (1999-01-01), Leistner
patent: 6129493 (2000-10-01), Leistner et al.
patent: 6183181 (2001-02-01), Leistner et al.
Leistner Herbert E.
Weiss Lloyd
Sigma Tool & Machine
Spiegel H. Jay
Weiss Lloyd
Wilson Neill
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