WO1999015797A1

WO1999015797A1 - Improved fasteners and methods of making same

Info

Publication number: WO1999015797A1
Application number: PCT/CA1998/000910
Authority: WO
Inventors: W. Lee Webster; Garth Bechtel; Jack Stewart
Original assignee: 3197719 Canada Inc.
Priority date: 1997-09-25
Filing date: 1998-09-25
Publication date: 1999-04-01
Also published as: AU9249198A; CA2216496A1

Abstract

A fastener comprising a head (1), shaft (2) and tip (3), the tip having an indent (4) formed therein such that the rim of the indent portion forms a cutting edge (5), and methods of making same is provided. The invention is particularly suitable for use with nails but is also useful for fasteners such as screws and spikes. The indent (4) and cutting edge (5) of the tip (3) provide for a fastener which requires less force to be driven into isotropic materials such as concrete and anisotropic materials such as wood and exhibits greater holding power than conventional fasteners such as diamond pointed nails. The use of the fastener of the invention in association with wood reduces the chances of the wood splitting as the fastener is being driven.

Description

IMPROVED FASTENERS AND METHODS OF MAKING SAME

The present invention relates to new and improved fasteners including nails and screws and methods of making same. The novel fastener comprises a head, shaft and tip, the tip having an indent formed therein such that the rim of the indent portion forms a cutting edge. The invention is particularly suitable use with nails but is also useful for fasteners such as screws, bolts and spikes. The indent and cutting edge of the tip provides for a fastener which requires less force to be driven into isotropic materials such as concrete and anistropic materials such as wood and exhibits greater holding power than conventional fasteners such as diamond pointed nails. The use of the fastener in association with wood reduces the chances of the wood splitting as the fastener is being driven.

Background of Invention

Glader, (Chapter 9 entitled "Nail Manufacture" of the Steel Wire Handbook, page 317), teaches that nail fasteners have not varied much since their early beginnings, approximately 3,500 years ago. A nail still consists of a long narrow piece of metal or hardened material such as wood or plastic with a taper or point on one end for piercing material and a bulge or flattening on the other end to be hammered. The purpose of a nail fastener is to hold two or more pieces of material such as wood or metal together, essentially by friction between the nail and the material.

Until about 1880, nails were hand-forged, first from copper and bronze, and finally from iron. As a result of these labour intensive, primitive blacksmithing techniques, nails were extremely valuable. There were few production changes in hand methods of nail manufacturing (except for refinements of the tools) until about the late lβth century in England and Sweden, at which time a major development in hand made nails occurred, namely the introduction of nail rods rolled from iron bars in slitting mills. The process consisted of the nail maker, in turn: cutting an iron rod to length; heating several cut lengths in a fire; pulling one length from the fire and tapering the shank of the nail to a point using a hammer and anvil; cutting the rod to a desired length; placing the cut length in a vice with the cut end projecting; and forming the head by striking the projecting end with a hammer to give it a mushroom shape. In about 1780, the first step toward mechanical nail making took place with a crude machine that cut tapered pieces from a plate. Heading was accomplished first by hand, and then was incorporated into the plate cutting device.

The first wire nail making machines appeared in Europe in about 1835 and were introduced into North America in about 1850. The process today for making nails incorporates basically the same manufacturing methods as originally developed in the early 1800' s. Specifically, nails are predominantly manufactured today from drawn steel wire using a three-shaft machine (designed shortly after World War 1) known as the Glader Machine, which consists of a flywheel and drive, header die, grip die, point cutter and wire feed device. A spool of nail wire is fed through a wire feed device and, subsequently, through open stationary grip die and point cutter. The grip die then closes to hold the wire. The end of the wire protruding from the grip die is then punched by the header die thereby forming the nail head. The header die then retracts, the grip die opens, the nail wire fed through the stationary open grip die to the desired nail length, and then the grip die closes to again hold the nail wire. The point cutter, positioned in parallel to the grip die, then travels and simultaneously cuts the point on the nail and severs it from the nail wire spool. The nail is then optionally ejected from the device with the aid of a mechanical "kicker". The grip die then opens to allow the wire feed device to feed more wire into the machine to form the head of the next nail. The process is then repeated.

Although a greater degree of dimensional accuracy and consistency in the manufactured nails was achieved through the use of the Glader Machine, inherent limitations in structure of the point cutters resulting from their positioning and wear on the point cutter and gripper dies resulted and continues to result in dimensional inaccuracies and inconsistencies in the formal nails. Typical examples are burrs resulting from the optional kicker detaching the formed nail from the nail wire feedstock and unevenly sized faces formed on the nail tip by conventional diamond tip point cutter dies.

There have been few developments in the manufacture of nails since the development of the Glader Machine. Those developments include the advent of tungsten carbide nail tooling and dies in the 1950' s, magnetic lift conveyors and cardboard packaging (nails were formerly shipped and sold in wooden barrels) . Tungsten carbide nail tooling increased the lifespan of the grip and head dies and point cutters. Magnetic lift conveyors made it easier for the manufacturer to collect and package nails formed by the Glader Machine process. Cardboard packaging resulted in easier transportation, storage and use of the nails. However, with the exception of tungsten carbide dies, none of these improvements improved the dimensional accuracy and consistency of the formed nail or improved or altered the functionality of the nail.

Commencing in the late 1950' s, increased labour costs and over supply resulted in nail manufacturing becoming only marginally profitable. However, the development of the portable automatic nailer has substantially increased the demand for nails. Construction workers using automatic nail guns not only accomplish their nailing jobs faster than using the traditional handheld hammer, but tend to use a substantially greater number of nails for any particular job.

Automatic nailers have not only increased demand, but have sparked a requirement for nails that are dimensionally accurate and consistent enough to be fed through a collator and then "fired" from a nailing gun. These requirements have resulted in the development of nail manufacturing machines by companies such as Wafios Machninenfabrik and Glader which produce nails with greater precision and tighter tolerances. However, the basic principles of making nails with these machines has not changed from the turn of the century Glader Machine .

It is generally known that the behaviour of nails in wood and other fibrous and non-fibrous materials is affected by many factors including the diameter and cross- sectional profile of the nail, the shape of the tip of the nail, the length of the nail shaft, the nail material and shaft surface texture. Any carpenter or home handyperson realizes that it takes more effort to hammer nails having large cross-sectional areas or longer shafts. Iron nails are more brittle than steel nails. Plastic nails are not suitable for fine woodworking applications. Thus, it is self-evident that the physical and engineering characteristics of fasteners such as nails are a direct function of their shape and composition.

In fibrous materials such as wood, fasteners such as conventional diamond pointed wire nails pierce the wood as a result of force being applied to the head of the nail by hammer, nail gun charge, spring or other means. As the nail enters the wood, the wood fibres are pierced by the tip of the nail, which are then forced apart latterly by the force applied to the head of the nail. The sides of the diamond tip of the nail assist in separating the wood fibres.

If a nail is driven through a perfectly isotropic material, the nail asserts force on the material in the direction that the nail is being driven (along the axis of the nail shaft) . The nail also asserts force on the material around the circumference of the shaft equally in all directions perpendicular to the shaft. The nail is then bound to the material by the compressive forces asserted by the material in opposition to the circumferential force asserted by the shaft. In a perfectly isotropic material, the compressive forces are distributed equally around the circumference of the shaft.

The manner in which the nail is bound to the wood differs when a nail is driven through an anistropic material such as wood. Although the circumferential force asserted by the nail continues to be equal in directions perpendicular to the shaft and the nail is bound to the material by countervailing compressive forces, the compressive forces are not distributed equally around the circumference of the shaft because of the anisotropic nature of the material. In the case of a fibrous material such as wood, the nail tends to separate the fibres. The result is that greater compressive force is asserted perpendicular to the direction of the fibres being separated by the nail shaft.

As a result, the strength with which the nail is bound to the wood varies considerably depending upon the constitution, shape and size of the particular piece of wood into which the nail is being driven. If the wood fibres are strongly bound to each other, the nail will grip better than if the fibres are not strongly bound. If the nail is being driven into a piece of wood having a knot, the nail will grip differently than if it were driven into a piece of wood not containing a knot. A conventional diamond pointed nail driven into isotropic fibrous material has materially lesser holding power than a conventional nail driven into an isotropic non-fibrous material where the compressive force is constant and uniform.

The separation of fibrous material by conventional diamond pointed wire nails also forcefully separates the fibres increasing the chances of the fibrous material being split. If a nail splits the wood fibres, the strength with which the nail binds to the wood drops considerably. This is a result of the fact that the nail is consequently gripped only by the compression force asserted against the nail shaft by the portion of the fibres which remain in contact with shaft. When a nail splits wood, the compressive forces asserted by the wood against the nail shaft (thereby binding the nail firmly to the wood) are relieved by the splitting of the wood. In short, the compressive forces which would otherwise grip the nail to the wood are dissipated by the energy expended in splitting the wood. The probability of splittage increases considerably where the piece of wood in which the nail is driven is thin, the nail is driven close to the edge of the wood, the fibres in the piece of wood are coarse, the wood is dry, in soft lumber, and where the nail is driven into the wood with excessive force (such as by a nail gun) .

The disadvantages associated with the decreased holding power and splittage associated with conventional diamond pointed wire nails may, depending upon the application, be material. Although in many applications these deficiencies may not be of concern, holding power and splittage are nevertheless important in many applications. First, as a result of lesser holding power and increased splittage, many more conventional diamond pointed wire nails may be required in order to achieve the desired holding power in a particular project. Secondly, the splitting of the wood in a particular application may necessitate that the wood be replaced. This is of particular concern in those applications where splittage and lesser holding power are not desirable such as in: the woodworking of fine and expensive grades of wood (eg. teak, mahogany, etc. ) ; the woodworking of relatively thin pieces of wood (eg. chair rail mouldings, wood shingles, etc.); wood exposed to the elements (eg. pressure treated deck boards, roof boards, exterior wood panels, etc.); applications where the nail must be driven in close proximity to the edge of the wood; and applications involving relatively cheaper, less dense and highly fibrous grades of wood. Thirdly, splittage is of particular concern with conventional diamond pointed wire nails used in nail guns. All of these disadvantages result in increased direct costs, labour and wastage.

As with manufacturing techniques, very few developments have occurred in the construction of nails over the years. As in Roman times, a nail still generally has a shaft, head and a pointed tip. We can speculate that innovation has not occurred in the form and manufacture of wire nails because of the low profits associated with the manufacture, inherent limitations in the form of the nail caused by the structure and methodology of the Glader Machine nail manufacturing processes, and a general perception by the nail manufacturing industry and the consumer that conventional diamond pointed wire nails are "good enough" to accomplish any particular job.

Manufacturers are driven to conventional diamond points by the configuration and orientation of the point cutters in the Glader Machine. The point cutter dies used in Glader Machines are not readily adaptable to forming shapes other than conventional diamond pointed tips. The point cutter dies travel perpendicular to the longitudinal axis of the nail wire and are therefore only capable of accomplishing a shearing function. A sharp, knife edged cutter die oriented perpendicular to the longitudinal axis of the wire will merely shear the wire thereby forming a nail with a blunt tip which is particular unsuitable for nailing applications. Point cutter dies having inclined cutting surfaces relative to the longitudinal axis of the wire or inclined parts on their cutting surfaces are adaptable to form "chisel" pointed tips or the conventional diamond pointed tip. As a practical matter, misaligned or work cutting dies result in malformed tips thereby decreasing the efficacy of the nail.

An inspection of any box of nails at a local hardware store will show that little attention is given by most nail manufacturers to the formation of accurate nail tips, again no doubt due to the prevailing market view that even malformed nails are "good enough" to accomplish most jobs. Little thought has also been given to the formation of nails having tips other than the traditional diamond tips. Even though the header die of a Glader Machine travels in the same longitudinal direction of the wire to form the nail head, the relative positioning of the header and grip dies is such that other mechanical forming functions travelling in the same longitudinal direction of the wire have not been adapted to such machines. It is perhaps not surprising that much of the development in fastener technology took place in relation to railroad spikes in the late 18th and early 19th century.

U.S. Patent No. 413,342 to Goldie teaches a method of pointing railroad spikes consisting of swaging the point of a spike to produce front and rear compressing surfaces, and then producing a sharp edge by shearing off the surplus metal obliquely across and in the direction of the length of the grain or fibre of the rolled iron. The method of the patent forms an icon spike having one or more sharp and clean cutting edges, and with smooth surfaces. Figures 7, 8, 9, 10 and 11 illustrate spike points manufactured by the method of the Goldie patent. The sharp cutting edges permit the spike to enter the wood by dividing or severing the grain of the railway tie with a clean cut. The inclined compressing surfaces on the front and sides of the point portion, on being forced into the timber, force the divided fibres of the wood backward or outwardly and form a compact and solid wall, thereby improving the holding qualities of the spike. The disadvantages associated with the spikes formed of the Goldie patent are that the spike tips are not readily adaptable to smaller fasteners such as nails. Also, the holding power of the spike is proportional to the orientation of the cutting edge of the spike to the wood grain. This is also not particularly suitable for smaller fasteners such as nails used in applications where it is inconvenient or impossible to orient the nail in relation to the grain of the wood (eg. nail gun applications) .

U.S. Patent No. 471,658 to Todd teaches a railway spike consisting of an improvement on one of the spike tips taught by Goldie. Todd discloses a spike having a plurality of points and an oppositely inclined shear cutting edge extending at its widest points, which points are bevelled to form cutting edges on the outside of the spike. As in Goldie, the Todd patent teaches a spike having a sharp cutting edge. However, Todd teaches a plurality of points being formed on the sharp cutting edge, with the result that the that the shear cutting edge is concave, as illustrated in Figures 2 and 4, or serrated as illustrated in Figure 5. The Todd spike appears to be more efficient than the Goldie spike as the plurality of the points on the cutting edge make it easier for the spike to be driven into the railway tie. The disadvantages associated with the Goldie spike tips are also associated with the Todd spike tips.

U.S. Patent No. 593,880 to Dupuis teaches a railway spike comprising a flanged head having an enlarged portion adjacent thereto. The body of the spike is preferably of uniform size through its length, with a bifurcated point. The bifurcated point forms a pair of similar legs each of which is provided with a bevelled barb or spur on its extreme lower end which extends outwardly therefrom. A sheathing is required to lock the spike in position. The spike is locked into position by being driven into the sheathing. The barbs or spurs formed on the extreme lower end of the spike make it easier for the spike to be driven into the railway tie. However, the Dupuis spike is not practically adaptable or useful for conventional fastener applications, and suffers the same disadvantages as does the spikes claimed in Goldie and Todd. U.S. Patent No. 1,737,206 to Stohr teaches a railway spike having a series of semi-circular downwardly sloped ledges formed on the shank of the spike arranged alternately at diametrically opposite sides of the shank. The tip of the spike has a tapered point C with a plurality of downwardly directed notches C ' gradually enlarged to the tip and forming a cross-shaped end with chisel like extremities. The head of the spike is formed with an elongated flange to engage the rail flange. The spike is to be driven into the railway tie in close proximity to the rail and then given a quarter turn to engage the head of the spike with the rail flange. When the spike is turned, the ledges act as threads forcing the spike deeper and more solidly into the railway tie. The Stohr spike is not practically adaptable for conventional fastener applications, and is particularly, if not uniquely, suitable for railroad ties. The tip of the Stohr spike appears to be similar to the chisel tip disclosed by Goldie and suffers the same disadvantages of the Goldie spike for conventional fastener applications.

U.S. Patent No. 1,813,805 to Humphris teaches a method of manufacturing pointed fastening devices having hollow shanks from sheet metal. Figure 1 illustrates a face view of a piece of sheet metal broken from one corner. The sheet metal is provided with a so-called V-like perforations (a) by means of the grooved punch illustrated in Figure 5. The method taught by Humphris results in a double pointed fastening device of the kind indicated in dotted lines in Figure 1. The double pointed fastening device illustrated in Figure 1 appears to be similar to the tip of the spike illustrated in Figure 5 of the Todd patent, and suffers the same disadvantages of the Todd spike for conventional fastener applications. Canadian Patent No. 61,551 to Button teaches an improved nail which is not liable to split wood. The nail consists of making the pointed ends of nail with a bevelled face on each side and a reversed V-shaped notch at the extreme end of the nail to provide two inclined cutting edges. The effect of forming the reverse V-shaped cutting edge on the end of the nail, as illustrated in Figures 1 and 2, is to bifurcate it and form two separate points the outer edges of which are parallel with the shank or body of the nail. The points are formed with a bevelled face on each side as indicated at C in Figure 2. The Button nail tip appears to be similar to the tip of the spike illustrated in Figure 5 of the Todd patent. Button teaches that the nail construction is not so liable to split the wood into which it is driven when driven across the grain. The stated advantage is that the reverse cutting edge draws the fibres together and cuts cleanly through them instead of wedging them apart as is the case with conventional nails. Also, the cut fibres act as a number of "pawls" which grip the nail to ensure tighter hold in the wood. A disadvantage associated with the Button nail tip is that the holding power of the nail is proportional to the manner in which the cutting edge of the nail is oriented to the wood grain.

U.S. Patent No. 1,771,867 to Stronach (Canadian

Patent No. 313,690) discloses a nonsplitting wire nail having a non-pointed entering end which crushes and cuts fibre. Stronach teaches a nail comprising a head, a substantially cylindrical body and a triangular entering end. The triangular entering end is formed by three sloping convex surfaces formed into the end of the body of the nail. The apices of the triangle join the body by ridges extending above the convex surface. Stronach teaches that his nail cuts and crushes the fibre thereby causing the nail to be gripped substantially throughout its circumference. Stronach teaches that a "concave" entering face is formed by deforming material adjacent the face without removing any material, and that it is highly important that the triangle have an area equal to a material portion of the cross sectional area of the nail otherwise the nail will have a wedging action similar to that of the usual type of nails.

The manufacturing techniques would not, on formation of the sides of the Stronach tip, result in the formation of a concave entering face. Rather, the tip would be blunt or at best imperfectly formed. The drawings illustrating the Stronach patent appear to illustrate that the triangular edges which he claims are formed on the tip are, in fact, an artifact of the manufacturing process whereby the three convex surfaces on the tip of the nail are formed. In effect, there is only a roughly triangular face on the end of the nail caused by the sheared metal created by the formation of the sides of the tip being pushed into a crude triangular shape on the tip. This deformed material could not serve as an effective cutting feature because it would be highly irregular in shape and density. It is also apparent that the process of manufacture of the Stronach nail would not result in a triangular shape. In order to form even a crude triangular shape, each of the three convex sides of the nail would have to be formed simultaneously, which, as noted, is not possible on a Glader Machine. More importantly, Stronach' s references to a concavity in his patent is a reference not to a hollowed area on the tip, but rather the concavities formed by each face of the tip 15 and the cutting edges being the ridge lines formed by the concavities 16 (see lines 90 to 95) .

There are a number of disadvantages associated with the Stronach nail. The non-pointed entering end taught by Stronach is difficult, if not impossible, to form by three- stage nail manufacturing machines which cannot knowingly be adapted to form three convex surfaces on the tip of a nail. Even if such surfaces were formed, the triangular entering end of the Stronach nail has a cross sectional area equal to a material portion of the cross sectional area of the nail. Therefore, although the nail may enjoy certain cutting and crushing advantages of conventional diamond pointed wire nails, the substantial cross sectional area results in additional force having to be asserted in order to drive the nail into the wood. The tip of the Stronach nail is also not adaptable for spiral shaped nails as the convex sides of the tip and triangular entering end would resist the spiralling action of the Ardox nail when it was being driven into wood. Farrell in U.S. Patent No. 1,921,514 states that the Stronach nail punches a triangular shaped hole. Farrell also teaches that the Stronach nail spreads the fibres of the wood apart when it is driven into a board, and as a result, void or non-gripping spaces are formed around the circumference of the body portion of the nail, thereby reducing its holding power.

U.S. Patent No. 2,044,740 to Stronach teaches a variety of nail tips and methods of manufacture. Stronach claims a non-splitting nail having sloping surfaces joining the body and a "blunt" entering face. The nail of the invention is illustrated in Figure 4 and has a circular body portion 32, reduced entering portion 33 and "cup-shaped" hexagonal end 34. The roughened cup shaped formation is formed by the manufacturing process whereby the slope of the forming portions of the cutting dies 25, 26 and 27 force the nail away from the cutting edge 28 as it is sheared by the angular compression of these cutting surfaces giving it the cross-section shown in Figure 5. Figures 4 and 5 appears to illustrate the nail claimed by Stronach in his U.S. Patent No. 1,771,867. Other similar dies are illustrated in Figure 6 where the V-shaped cutting wall 40 is stated to cause an exaggerated cupping on the end of the nail, Figure 7 where the end cutting edge 47 is arcuate in form and is stated to assist in forming a cupped end and Figure 13 which is stated to form a cupped end.

It appears that although Stronach speaks of a "cup- shaped" hexagonal on the end of the nails, this, in fact, would not occur with the use of claimed dies. He teaches that the tip is formed by the shape of the die by two steps that occur in the manufacturing process. The first step (lines 35 to 42) is that as the nail is "sheared there is a tendency for the nail to be forced away from the cutting edge 28 by the angular compression of these surfaces. This occurs while the compression is taking place and results in a cupping of the entering end of the nail". The second step is disclosed in lines 57 to 63 where he states that in such dies the nail is "deliberately not fully cut and the uncut surface is fractured by the action of the kicker which knocks the nail off the end of the wire. This broken surface formed in this manner has been found to be generally cup-shaped, similar to that shown in cross-section in Figure 5. By breaking the nail away, sharp edges are formed at the edge of the cup ... " .

It is apparent from this disclosure that a cup shaped tip cannot be formed by the methods disclosed in the Stronach patent. All of the aforementioned dies discussed by Stronach are used in place of the dies that would be traditionally be used to form conventional diamond pointed tips. When diamond tips are formed, the dies grip the nail wire forming the tip and thereby sever the formed nail from the wire stock (the head having been formed in the immediately preceding operation) . A kicker is necessary in order to dislodge those nails from the heading machine that might not have been completely severed from the wire stock. The dies taught by Stronach would appear to result simply in the nail being bound to the wire stock with a greater cross sectional area than what would be the case with dies forming traditional diamond points. The cross sectional area would differ in shape depending upon the die used. When the kicker dislodged the nail from the wire if at all the kicker would cause the tip of the nail to be sheared or blunt.

Secondly, a cupping would not occur as a result of the nail being forced away from the cutting edge as taught by

Stronach. When the shearing dies close on the nail wire, the wire is compressed circumferentially into the shape prescribed by the die. In doing so, the portion of the nail wire opposed to the grip die is forced away from the shear die and grip die by the compressive action of the shear die.

However, this cannot result in the cupping of the entering end simply because the entering tip has not been formed.

There is no tip formed until the shear dies complete the shearing operation. With the dies taught by Stronach, the tip is not formed until the kicker is provided to knock off the formed nail from the nail wire feed. In either case, it is impossible for the shearing force of the dies, or in the case of the Stronach dies, until kicked off the feed stock.

Thirdly, it is impossible for a cutting to occur by the fracturing action of the kicker which knocks the nail of the wire feed stock as taught by Stronach. He teaches that the broken surface on tip has been found to be general cup shaped, and that sharper edges are formed which assist in shearing action. In claim 5, he teaches that the nail of his invention is formed by "breaking the stock at the reduced point". When a kicker knocks a nail off feed stock, the action of the kicker is also a shearing function. It cannot provide any force in the longitudinal direction of the axis of the nail as would be necessary to form any cupped shape. At most that shearing function would result in a blunt end, as appears to have been the discovery disclosed by Stronach in page 1, column 1, lines 8 to 25 of his patent.

Indeed, the Stronach nail appears to reflect a method which carpenters have traditionally used in order to reduce the chances of wood splitting in delicate woodworking applications. It is generally known by carpenters that the blunting of the tip of a conventional diamond pointed nail will decrease the chances of wood splitting. Carpenters blunt the tips of conventional diamond pointed nails by positioning the tip of the nail on a hard object such as an anvil or piece of steel and striking the head of the nail with a hammer, thereby creating a distorted, yet blunt, diamond tip.

U.S. Patent No. 1,921,514 to Farrell claims a nonsplitting nail comprising a head and shank having a tapered driving end, the surface metal of said shank adjacent the driving end being projected beyond the end of the shank to provide an annular cutting edge of smaller diameter of the body of the nail. The tapered end of the nail terminates in a "dished-out" surface to provide a closed cutting edge similar in shape to a transverse section of the shank of the nail but of smaller dimensions than the dimensions of such a section. The entering end 13 is hollowed out forming a concave surface 14 on the end of the nail and a closed annular cutting or knife edged 15 which is concentric to the axis of the body of the nail. Farrell claims that when the nail is driven into a piece of wood, the cutting or knife edge 15 on the concave surface positively cuts or severs the fibres of the wood instead of spreading them apart thereby preventing the wood from splitting.

Farrell teaches that the improved nail is formed by forming the head in a suitable die and the wire is then cut or sheared to the desired length. After the shearing operation, the blank nail is rolled about its longitudinal axis while the end is gripped by members having their opposed faces inclined one to the other to form the concave entering end. It is not clear from the description in the Farrell patent how the tip of the nail is actually formed. Although the nail blank consisting of the nail and head without the formed tip can readily be formed in conventional nail machines, Farrell does not teach specifically how the nail blank can be rolled about its longitudinal access, nor how opposing gripped members having their opposed faces inclined to one another can form the concaved entering end. If the nail is gripped and pinched by opposing members without being rotated, a concave bowl will not form in the tip of the nail. If the nail blank is rolled while gripped, a tip will not be formed. Rather the nail blank will be spiralled.

Brief Summary of Invention

It is an object of the present invention to provide a new and improved nail and screw fasteners and a method for making same.

It is a further object of the present invention to provide fasteners that have greater holding power in fibrous and nonfibrous material than conventional diamond pointed wire nails or conventional screws.

It is a further object of the present invention to provide fasteners which take less energy to drive into fibrous and nonfibrous material than conventional diamond pointed wire nails or conventional screws.

It is a further object of the present invention to provide fasteners that are better than conventional diamond pointed wire nails or conventional screws in preventing the splitting of fibrous material such as wood.

It is a further object of the present invention to provide fasteners that enjoy all of the aforementioned benefits and attributes with the result that fewer fasteners than conventional diamond pointed wire nails are required for any particular job application.

It is a further object of the present invention to provide a method of manufacturing such fasteners which is cost effective, yet reliable and efficient to use.

It is a further object of the present invention to provide a new and improved nail which enjoys all of the aforementioned advantages. The present invention will thereby result in cost savings based on raw material costs to job contractors, savings in resources due to the fact that fewer nails will be required in order to accomplish a particular job function and to manufacture and transport those nails to job sites, savings due to less wastage resulting from split or damaged wood, and greater holding power.

The aforementioned disadvantages may be overcome by the present invention which provides for a fastener comprising a head, shaft and tapered tip, the tip having an indent formed therein such that the rim of the indent portion forms a cutting edge. The tapered tip may be diamond shaped. The fastener of the present invention may be a nail, screw or spiralled nail. In its preferred embodiments, the indent formed therein may be concave or cylindrical in shape. The indent may also be formed by the use of a hollow tube like nail wire. The edges of the indent may also be serrated. The present invention also provides for a method of forming such fasteners comprising securely gripping a fastener comprising a head, shaft and tapered tip and forming the indent of said tip by forcefully applying an indenting means to said tip in the direction of the longitudinal axis of the fastener.

The present invention further provides a method of forming nail fasteners comprising feeding a continuous feed of nail wire through an open grip die, causing the grip die to securely grip the nail wire, causing a header die to travel in the direction of the longitudinal axis of the nail wire in the opposite direction to the feed of nail wire causing the header die to strike the nail wire feed thereby forming the nail head, causing the grip die to open thereby allowing a further feed of the nail wire through the open grip die to the desired length of the nail, causing the grip die to again close firmly gripping the nail wire, causing point cutter dies to cut the nail wire contiguous with or close to the grip die thereby forming a tapered tip, causing the formed nail to be gripped by or fed into a second grip die which securely grips the formed nail, and causing an indenting die to apply an indent into the tip of the formed nail . The present invention further provides a method of forming nail fasteners comprising feeding a continuous feed of nail wire through an open grip die, causing said grip die to firmly grip the nail wire, causing point cutter dies to cut the nail wire thereby forming a tapered tip, causing an indenting die to apply an indent into the tip of the nail wire, causing the grip die on the nail wire to be closed so that the nail wire with tip can be fed to the desired length of the fasteners, causing a second grip die to firmly grip said fastener, causing point cutter dies to cut the nail wire with the formed tip the desired length of the nail fastener, and causing a header die to strike the fastener of the opposite end to the tip to form the nail head.

The present invention further provides a fastener comprising a head, shaft and tip, the tip having a hollow portion formed therein such that the rim of the hollow portion forms a cutting edge, said hollow portion having been formed by the use of hollow wire stock.

Brief Description of the Drawings

These and other objects which will be made readily apparent to those skilled in the art are obtained by means of this invention, certain embodiments of which are described in the following specification and which are illustrated in the accompanying drawings wherein:

Figure 1 is a view of a conventional diamond tipped nail having bearing a convex indent formed in the tip of the nail.

Figure 2 is a view of a spiralled conventional diamond tipped nail having a convey indent formed in the tip of the nai l .

Figure 3 is a view of a diamond tipped nail manufactured from hollow wire nail stock.

Figure 4 is a schematic diagram of a three-shaft nail machine.

Figure 5 is a schematic diagram illustrating the operation of nail making performed by one of the preferred embodiments of the invention.

Description of Preferred Embodiment of Invention

The present inventors have discovered that the disadvantages associated with traditional fasteners such conventional diamond pointed nails can be reduced significantly by the fasteners of the invention. The fastener of the invention exhibits greater holding power than conventional diamond pointed nails in purely or partly isotropic materials (such as certain plastics and concrete) and in anisotropic materials. Since the fastener's holding power is increased, fewer fasteners may be used for any particular application. Also, fasteners of a smaller diameter shaft may be used. The fastener of the invention is particularly useful for overcoming the problem of splittage associated with conventional nails when used in association with anisotropic materials such as wood.

The fastener of the invention also requires less force to be driven into the material thereby rendering the fastener particularly suitable for use in association with construction jobs such as roofing which require large numbers of nails to be manually driven by workers. The invention also exhibits advantages for nail gun applications where a smaller charge or spring load is required than conventional diamond pointed nails. The benefits of the fastener may also be achieved in anisotropic material such as wood notwithstanding the manner in which the fastener is oriented to the wood grain. The fastener of the invention is also particularly suitable for fasteners of all sizes.

The advantages associated with the present invention flow from the novel and inventive shape of the fastener tip, specifically the formation of an indent on the tip to form a cutting edge. Referring to Figure 1, which illustrates a preferred embodiment of the invention, a conventional diamond tipped nail bearing a convex indent formed in the tip of the nail is illustrated. 1 designates the nail head. 2 designates the nail shaft. 3 designates a conventional diamond shaped tip on the nail formed by diamond cutting dies during the manufacturing process. 4 designates the concavity formed on the tip of the nail such that the end of the nail is hollowed out forming a cutting edge 5. When a concavity 4 is formed on the diamond tip 3, a serrated cutting edge 5 is formed by the intersection of the planes of the diamond tip 3 and the concavity 4.

It has been found that when the indent 4 is formed on the tip 3, in a preferred embodiment in association with a tapered tip 3, the physical characteristics of the manner in which the nail is driven into the material vary considerably from conventional fasteners such as the traditional diamond pointed nail. When the fastener of the invention is driven into material, the tip of the fastener 3, as with conventional nails, pierces the material. However, it has been found that the cutting edge 5 formed by the indent 4 provides not only a piercing function but also results in three surprising consequences.

First, the cutting function decreases the compressive circumferential forces asserted by the material at any one point around the shaft of the nail as the nail is being driven into it as a result of the material being cut by the cutting edge 4 and not only being driven apart by the separation of the material by the inclined surfaces of the diamond tip 3 as is the case with conventional diamond pointed nails. Since less compressive force is asserted at any one point circumferentially about the nail shaft 2, the probability of the applied stress to the material being relieved through splittage in the wood fibres decreases considerably.

One might expect that the fact that less force is asserted circumferentially would result in the nail being bound not as strongly to the material by friction between the shaft 2 and the material into which the nail is being driven. Therefore, one might expect that the advantage of decreased splittage in materials such as wood might be counterbalanced by poorer holding power. However, it has surprisingly been found that this is not the case. Rather than decreasing the holding power, the fastener of the present invention increases the holding power in fibrous materials such as wood. ^' This is because even though less force is asserted at any one point circumferentially about the nail shaft 2, the total force asserted circumferentially exceeds the force that would be asserted had the nail merely split the fibrous material into which it is being driven. Where the nail splits the wood fibres, there is a stronger force asserted circumferentially at the points on the nail shaft 2 adjacent to the fibres being split, and a weaker (and possibly no) force being asserted parallel with the direction of the fibres .

Secondly, the cutting edge 5 dislodges parts of the material into which the fastener is being driven forming, in wood, a pulp like mass of material. The material is also dislodged as a result of the indent 4. Had the cutting edge consisted simply of a knife edge as is found in many railway spikes and disclosed in the prior art, material would also be dislodged, however, not as much material would be dislodged as is found with the fastener of the present invention. When the fastener of the invention is used with fibrous material such as wood, the cutting edge and indent create a mass of wood pulp forming at the tip of the nail in and about the indent 4, edge 5 and tip 3.

One might expect that the formation of this mass of material or pulp would have little or no affect on splittage of the material into which the fastener is being driven or holding power of the fastener. Indeed, one might expect that the formation of a pulp would decrease holding power because the pulp is neither bound to the fastener or to the material into which it is being driven. One might also expect that the pulp would lubricate the fastener shaft as the fastener is being driven into the material thereby decreasing holding power. However, it has surprisingly been found that rather than decreasing the holding power, the fastener of the present invention increases the holding power. This is because the pulp, as the fastener is driven, travels up the sides of the fastener shaft 2. As might be expected, the pulp serves to lubricate the fastener shaft 2 as it is being driven into the material. However, it has surprisingly been found that the pulp, once the fastener is in place, creates friction between the nail and material in si tu, thereby increasing the fastener's holding power. This friction exceeds the friction between the fastener shaft and the material into which the fastener is being driven had no pulp been present.

A third surprising consequence pertains to the manner in which the novel tip of the invention applies force to the material into which the fastener is being driven. As noted, a conventional diamond pointed nail will cause force to be asserted circumferentially around the nail shaft 2. Although there is some force asserted by the nail in the longitudinal direction of the nail shaft as it is being driven into the material, the tip of a conventional fastener such as a nail simply pierces the material into which it is being driven. However, with the fastener of the invention, the novel tip of the fastener causes force to be asserted longitudinally in the direction of the nail shaft. Because of the convex shape of the indent 4 on the tip of the fastener, that force is not dissipated entirely in a direction circumferentially around the nail shaft 2 perpendicular to the longitudinal direction of the fastener shaft 2, but also emanates from the tip of fastener 4 in the longitudinal direction of the fastener in a conical shape, with the apex of the cone emanating from the tip of the fastener.

The difference in the shape of the force field applied at the fastener tip of the invention results in a number of surprising advantages. As noted, the force is directed more in the longitudinal direction of the fastener shaft than in conventional nails. This results in less force having to be asserted against the fastener than with conventional diamond pointed nails in order to force the fastener the same distance into the material into which it is being driven. Secondly, the fact that greater force is dissipated in driving the fastener in the longitudinal direction of the fastener shaft decreases the tendency of anisotropic material, in particular, fibrous material such as wood, to split when a fastener is being driven into it. Thirdly, the longitudinal, conical shaped, force field enhances the formation of pulp at the tip, thereby enhancing the lubricating and frictional benefits described above. The behaviour of the conical force field at the tip emulates that exhibited by shaped explosive charges typically used in military anti-tank applications or in shaped hollow point bullets .

The novel tip of the invention preferably includes a tapered tip 3 in order to achieve the aforementioned advantages. However, the benefits of the invention can also be achieved by the use of a fastener having an indent 4 in its tip where the diameter of the indent is equal to that of the fastener shaft 2. A tapered tip 3 tends to enhance the benefits of the invention by providing an initial piercing function and a gradual increase in circumferential shaft force at any point in the material as the fastener is being driven into the material thereby gradually separating the wood fibres. A tapered tip 3 also allows for the invention to be used in association with nails of larger shaft 2 diameters, thereby increasing the holding power of two pieces of material bonded together and decreasing the chance of the shaft 2 bending upon being driven into the material. A diamond shaped tip as found on conventional nails is suitable for the invention (provided that the tip contains the claimed indent of the invention 4) . Other tip shapes such as conical tips, multi-sided points, and points having curved, inclined surfaces also exhibit the benefits of the invention.

It is essential that the tip of the fastener include an indent 4 or hollow portion. Preferably the indent is concave 4 in shape thereby forming a cutting edge 5 on the rim of the concavity. That indent may also be of other shapes including conical, cylindrical or irregular in shape, provided that the shape includes a cutting edge and a hollow portion. The benefits of the invention appear no matter how deep an indent is formed in the tip, although it has been found that it is preferable that the depth of the indent not exceed the diameter of the indent.

It is readily apparent that the shape of the cutting edge on the indent will vary depending upon the shape of the indent and tapered tip. A concave indent formed on the shaft of a nail without a tapered tip will form a clean bowl shape with a circular, smooth cutting edge. In a preferred embodiment, a circular, smooth cutting edge will form when a concave bowl is formed on a conically tapered tip. In a preferred embodiment, such as that illustrated in Figure 1, a serrated cutting edge 5 is formed when a concave bowl is formed on conventional diamond tapered tip or multi- sided tip, the serrations being formed by the intersections of the edges of the flat tapered cuts forming the diamond shaped tapered tip or multi-sided tapered tip with the hollow tip. The serrated cutting edge 5 assists in the cutting and pulp creation function described above.

The advantages of a serrated cutting edge 5 are particularly evident in a further preferred embodiment of the invention namely the use of the fastener of the invention in association with an Ardox or spiral nail as illustrated in Figure 2. Spiral nails are formed by drawing nail wire through a die which twists the nail wire into a spiral shape 6. Spiral nails have greater holding power than conventional straight shafted nails. As they are driven into material such as wood, the spiral shaft 6 causes the nail to turn about its longitudinal access with the result that the nail shaft is screwed into the material in a similar manner to that associated with conventional screw fasteners. The advantages of the present invention are enhanced when used in association with a spiral nail bearing a conventional diamond shaped tip or multi-sided tapered tip as illustrated in Figure 2 because the serrated edges formed on tip 5 rotate about the axis of the fastener shaft as it is being driven into the material. The circular rotation of the serrations on the tip 5 creates a sawing effect on the material further enhancing the cutting power of the nail and the creation of pulp.

The advantages of the invention are exhibited no matter where the indent is located on the tapered tip of the fastener. However, it has been found that the advantages of the invention are particularly evident for material such as wood when used in association with a conventional diamond pointed industrial nail where the indent is located on the diamond tip approximately one third up the taper of the tip from the point of the nail where the tip would have otherwise formed but for the indent.

A further advantage is associated with fasteners of the claimed invention when formed in accordance with these methods. The formation of an indent on the tip of the nail either by an indenting die or drill bit results in a distortion of the metal grain structure of the nail tip. The application of the force necessary to distort the tip and resulting heat, in the case of a die, and the heat and force resulting from the rotating drill bit, fractures the metal grain structure of the tip thereby resulting in a hardening of the tip. The hardened tip assists in driving the fastener through the material, and decreases the chances of the indent and cutting edges being distorted as the fastener is being driven.

The advantages of the present invention are particularly suitable for use with nails. However, they are also exhibited with other fasteners such as conventional screws, bolts, studs or other fasteners which must be driven into isotropic or anisotropic materials. For example, the advantages of the claimed invention are exhibited when used with bolts to secure objects to concrete. The fasteners of the invention are also particularly suitable for use in nail guns. A smaller charge or spring loaded force is required in order to drive the fasteners of the invention than with conventional fasteners.

The tip of the invention also exhibits the beneficial characteristics of the claimed invention when a conventional tip is placed on a nail formed from hollow nail wire stock. Figure 3 illustrates a preferred embodiment of the invention where the fastener is formed from hollow material such as a hollow nail wire. In Figure 3, a hollow, cylindrical cavity 8 is formed within the fastener shaft 7 such as in a hollow nail wire feedstock 7. When a tapered tip 9 is formed on the shaft by, for example, conventional diamond point cutters, a cutting edge 10 is formed on the tip. The cutting edge 10 serves the same function as that described above with regard to cutting edges formed by an indent formed into the tip of a conventional nail, as illustrated in Figure 1. However, when the invention is used with a hollow nail wire, some of the pulp or material dislodged by the driving action of the nail travels up the nail wire's hollow internal shaft thereby decreasing its frictional in si tu holding power. In a preferred embodiment, it has been found that the benefits of the invention can be achieved by sealing the hollow cavity 8 in the nail wire close to the cutting edge of the tip 10. This can be achieved by, for example, pinching the shaft 7 of the fastener close to the part of the fastener where the tip 9 intersects with the fastener shaft 7. Preferably, the diameter of the hollow cavity 8 and the thickness of the walls of the hollow fastener 7 should be such that the structural integrity of the fastener is not impaired. If the diameter of the hollow cavity 8 in relation to the thickness of the sides of the shaft 7 is too great, the fastener will tend to bend when being driven into material such as wood. Also, if the diameter of the hollow cavity 8 is small in relation to the thickness of the shaft 7, the shaft of the fastener can be pinched, thereby sealing the hollow cavity 8, without materially impairing the structural integrity of the fastener.

There is one additional beneficial feature associated with using hollow fastener stock. Specifically, the fastener of the invention, such as nails, can be manufactured on traditional nail manufacturing equipment such as the Glader Machine described above, through the use of hollow fastener stock and point cutter dies shaped in a manner which enable the dies to not only cut the point 9 on the fastener stock but also pinch the fastener stock thereby sealing the hollow cavity 8.

The fasteners of the invention are formed preferably by securely gripping a fastener comprising a head, shaft and tip and forming the indent of said tip by forcefully applying an indenting means to said tip in the direction of the longitudinal axis of the fastener. This may be accomplished by holding a convex die consisting of a ball in a vice, and then securely gripping the fastener and hammering its tip onto the ball bearing. In a further preferred embodiment, fasteners of the invention may be formed by securely gripping the fastener, and forming the indent on the fastener' s tip by forcefully applying a rotating drill bit having a spherical or pointed tip to said tip in the direction of the longitudinal axis of the fastener .

Figure 4 illustrates a schematic diagram of a traditional three shaft nail machine of the Glader type. The machine typically consists of a flywheel and drive 11 which drives all of the features of the device including the header die 12, point cutter die 13, grip die 14, and wire feed device 16. The nail wire stock 17 is fed by the wire feed device 16 into the grip dies 14, 15, which grip the nail wire stock 17 firmly. The header die 12 then strikes the end of the nail wire stock 17 in the longitudinal direction of the wire stock thereby forming the nail head 18. After the nail head 18 is formed, the header die 12 retracts, and the grip die 14 opens. The wire feed device 16 then feeds the wire stock through the grip dies to the desired length of the nail. The grip die 14 then closes once again gripping the wire stock 17. The point cutter dies 13 then close to cut the wire stock, thereby forming the nail tip, and the entire nail. The point cutter dies 13 then retract and the grip die

14 opens enabling the process to be repeated. Optionally, it may be necessary for the formed nail to be dislodged from the nail stock wire after the point is formed by a "kicker"device

(not illustrated) . The formed nails typically then drop into a bin and are assembled for packaging and sale.

In a preferred embodiment of the invention, as illustrated in Figure 5, the fasteners of the invention are formed by a method consisting of feeding a continuous feed of nail wire 19 through an open grip die 20, causing the grip die 20 to firmly grasp the nail wire 19, causing a header die 21 to travel in the direction of the longitudinal axis of the nail wire in the opposite direction to the feed of nail wire causing the header die 21 to strike the nail wire feed thereby forming the nail head. The grip die then retracts 22. The grip die then opens 23 thereby allowing a further feed of nail wire 24 through the open grip die 23 to the desired length of the nail. The grip die 23 then again closes firmly grasping the nail wire 24, and point cutter dies 25 cut the nail wire contiguous with or close to the grip die thereby forming a tapered tip. Optionally, a kicker die (not illustrated) detaches the formed nail from the nail stock. The formed nail is grasped by or fed into a second grip die 26 which securely grasps the formed nail. An indenting die 27 (or optionally a rotating drill bit) then travels in the longitudinal direction of the nail thereby forming an indent into the tip of the formed nail. The formed nails of the invention are then assembled for packaging and sale.

Optionally, the formed nails may be machined or ground to remove undesirable burrs or excess deformed materials from the cutting edge of the tip of the nail. As mentioned above, when hollow nail wire stock is used, it is not necessary to utilize the additional step of grasping the formed nail and optionally indenting the tip. Rather, in a preferred embodiment, it may be desirable to shape the point cutting dies in a manner which pinches the nail wire stock simultaneously with the formation of the cutting point thereby sealing the hollow nail shaft. The aforementioned indenting dies may be convex in shape (to form a concave indent) or conical (to form a conically shaped indent) . The use of a rotating drill bit results in an indent shape which is the negative of the shape of the drill bit. Such shapes may be conical or bullet shaped.

The fasteners of the invention may also be formed by the aforementioned methods through the use of standard commercial wire nail presses such as the Wafios series N wire nail presses manufactured by Wafios Maschinenfabrik GmbH & Co. Kommanditgesellschaft, with suitable modifications to the presses. Through the use of such presses, the present invention can be adapted for use with nail wire diameters ranging from 1.0 to 10 mm, and nail lengths ranging from 10 - 300 mm through the use of Wafios series N3 to N8 and Nil to 61 wire nail presses . The invention is also suitable for production of nails having tight tolerance ranges. For example, the invention may be used on all standard commercial wire nails, nails with large shaped heads, nails with long points, high precision nails for subsequent automatic processing, double head and collar nails, rivet mandrels, T- nails, and roughened nails. Wafios series N 3 to N8 and Nil to 61 wire nail press may be adapted to manufacture the fasteners of the invention through the use of an optional attachment which grips the nail immediately after the tip cutting step and forms the indent of the invention on the tip. By way of example, a Wafios Nil nail wire press may produce an output of 900 nails per minute using one nail wire feed and 1800 nails per minute using a two nail wire feed.

Similarly, the fastener of the invention may be formed using a Wafios nail wire machine N 90. The Wafios N 90 is capable of producing 820 nails per minute (using 3.8 mm. diameter wire) . The Wafios N 90 machine differs from the Wafios series N to N 8 and Nil to N 61 in that it separates the cutting and head punching processes. Nail wire is first fed into the machine and then cut to the length of the nail blank, the cutting process forming a blank consisting of a length of nail wire with the tip (such as a diamond pointed tip) . The blank bearing the tip is then positioned for the head forming operation. The formed nails are then ejected from the machine into a second apparatus which forms the indent of the invention onto the tip of the nail. Alternatively, the tip bearing the indent can be formed in tip cutting operation of the Wafios N 90 by adapting the machine to form an indent at the time the tip is cut. The Wafios N 90 is particularly useful, after suitable modification, to manufacture the nail of the invention as it has a chip exhausting feature which allows the finished nails to emerge from the machine free of lubricants, drawing agents and chips. This eliminates cost intensive finish processing such as tumbling, scouring and polishing. A Wafios N 90 machine, suitably adapted, can manufacture nails of a wire diameter of 2.4 to 3.8 mm and a nail length of 55 to 98 mm.

Double die nail presses may also be used to manufacture the fasteners of the invention. In such presses, tandem, double "blow" presses individualize the traditional operations of feeding, cutting, pointing and heading the nail. In double die presses such as the Wafios N 80, wire is fed into the machine and then cut individually into a blank of a set length. A head is then formed on one end of the blank by a header press. A head is then formed on the other end of the blank by a second header press. The blank, named a "Janus" blank, consisting of two heads is then cut in its middle by cutter dies, thereby forming two nails, each bearing a head and tip. A Wafios N 80 machine may be adapted to form the nails of the invention by adapting either the first or second header dies to form an indent into the end of the nail blank. The head is formed by the other header die on the other end of said blank. The indented end of the blank is then cut by cutter dies forming a nail having a tip with an indent on the end of it. Optionally, one of the header dies may be modified to apply a die to the end of the nail blank which forms a diamond shaped tip bearing the indent of the invention. A Wafios N 80 machine can be suitably adapted to produce between 1600 to 3200 nails per minute, having diameters of 2.1 mm to 3.1 mm and lengths of 32 mm to 63.5 mm.

The indented tip of the invention can also be formed by indenting a blank nail of a set length prior to the formation of the tip. For example, the nail tip could be indented using an indenting die exerting force in the longitudinal direction of the nail tip, and then a diamond shaped tip cut using traditional diamond cutting dies. The indent of the invention can also be formed by applying a die in the longitudinal direction of the nail tip which forms the shape of the nail tip of the invention.

Having described the presently preferred exemplary embodiments of the fastener and methods for forming same in accordance with the present invention, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is, therefore, to be understood that all such modifications, variations, and changes are believed to fall within the scope of the present invention as defined by the appended claims.

Claims

WE CLAIM :

1. A fastener comprising a head, shaft and tip, the tip having an indent formed therein such that the rim of the indent portion forms a cutting edge, said indent having been formed by comprising securely gripping a fastener comprising a head, shaft and tip and forming the indent of said tip by applying an indenting means to said tip in the direction of the longitudinal axis of the fastener.

2. The fastener of claim 1 wherein the tip is tapered.

3. The fastener of claim 2 wherein the tapered tip is diamond shaped.

4. The fastener of claim 1 wherein the fastener is a nail.

5. The fastener of claim 4 wherein the fastener is a spiralled nail.

6. The fastener of claim 1 wherein the fastener is a screw or bolt.

7. The fastener of claim 1 wherein the indent is concave in shape.

8. The fastener of claim 7 wherein the area circumscribed by the circumference of the concave portion formed in the tip is one third the cross sectional area of the shaft.

9. The fastener of claims 1 or 5 wherein the cutting edge is serrated.

10. The method of forming the fastener of claim 1 comprising securely gripping a fastener comprising a head, shaft and tip and forming the indent of said tip by applying an indenting means to said tip in the direction of the longitudinal axis of the fastener.

11. The method of claim 10 wherein the fastener is a nail comprising feeding a continuous feed of nail wire through an open grip die, causing the grip die to securely grip the nail wire, causing a header die to travel in the direction of the longitudinal axis of the nail wire in the opposite direction to the feed of nail wire causing the header die to strike the nail wire feed thereby forming the nail head, causing the grip die to open thereby allowing a further feed of the nail wire through the open grip die to the desired length of the nail, causing the grip die to again close firmly gripping the nail wire, causing point cutter dies to cut the nail wire contiguous with or close to the grip die thereby forming a tapered tip, causing the formed nail to be gripped by or fed into a second grip die which securely grips the formed nail, and causing an indenting die to apply an indent into the tip of the formed nail.

12. The method of claim 11 wherein the indenting means is a convex or conically shaped die.

13. The method of claim 12 wherein the convex die consists of a ball bearing held in a vice and the die is forcefully applied to said tip by gripping said fastener and hammering the tip of the fastener onto the ball bearing.

14. The method of claim 10 wherein the indenting means comprises a rotating drill bit having a spherical or pointed tip.

15. A continuous method of forming nail fasteners comprising the method of claim 10 whereby a continuous feed of nail wire is fed through an open grip die, causing said grip die to firmly grip the nail wire, causing point cutter dies to cut the nail wire thereby forming a tapered tip, causing an indenting die to apply an indent into the tip of the nail wire, causing the grip die on the nail wire to be closed so that the nail wire with tip can be fed to the desired length of the fasteners, causing a second grip die to firmly grip said fastener, causing point cutter dies to cut the nail wire with the formed tip the desire length of the nail fastener, and causing a header die to strike the fastener at the opposite end to the tip to form the nail head.

16. The fastener of claim 1 wherein the tip of said fastener has been hardened by said indenting means.

17. A fastener comprising a head, shaft and tip, the tip having a hollow portion formed therein such that the rim of the hollow portion forms a cutting edge, said hollow portion having been formed by the use of hollow wire stock.

18. The fastener of claim 17 wherein the hollow portion is sealed in close proximity to the tip of the fastener.

19. A method of forming the fastener of claim 17 wherein the fastener is a nail comprising feeding a continuous feed of hollow nail wire stock through an open grip die, causing the grip die to securely grip the nail wire, causing a header die to travel in the direction of the longitudinal axis of the nail wire in the opposite direction to the feed of nail wire causing the header die to strike the nail wire feed thereby forming the nail head, causing the grip die to open thereby allowing a further feed of the nail wire through the open grip die to the desired length of the nail, causing the grip die to again close firmly gripping the nail wire, causing point cutter dies to cut the nail wire contiguous with or close to the grip die thereby forming a tapered tip, said point cutter dies also being formed in such a manner which pinches the shaft of the formed nail close to the nail tip thereby sealing the hollow cavity.

20. The method of forming the fastener of claim 1 comprising securely gripping a length of nail wire and forming a tip in a cut end of the nail wire consisting of a tip having an indent formed therein by the use of a die shaped to form the tip and indent.

21. The method of claim 20 wherein the head of the fastener is formed by applying a header die to the opposite end of the nail wire before, simultaneously with or after the formation of the indent on the tip.