US2309536A - Staple - Google Patents

Description

Patented Jan. 26, 1943 Irvin Maxwell Reid and Charles H. Johnson, East Jaffrey, N. H., assignors to United Shoe Machinery Corporation, .Flemington, N. J., a corporation of New Jersey Application March 31, 1941, Serial No. 386,055

3 Claims.

This invention relates to fastening members for use in securing materials together and more particularly to staples adapted for use in securing materials to walls.

Ordinary staples, while used for this general type of work for many years, have been found not particularly satisfactory for the work because of their lack of holding power and also because their thick, narrow bar portions not only do not cover much of the material operated upon but, when driven fiush with the work, have a tendency to, and often do, out through the layers or sheets of material operated upon with the result that the sheet material is damaged and the staple is renclered ineffective as a fastening.

An important object of the present invention is to provide an improved fastening member or staple of novel construction which will obviate the difiiculties refer-red to above in connection with the use of ordinary staples, and which will be particularly well adapted for use in securing sheet materials to walls even when the Walls are "composed of relatively soft, fragile or readily breakable material.

In some parts of the country, particularly in the southern and southwestern sections Where the climate is warm and where the extremes in humidity and. dryness are experienced during the year, the interior walls and ceilings of dwelling houses and other buildings are formed in many instances of a manufactured wall board product known as gypsum board or plaster board. These manufactured wall boards, as is well known, are composed of outside layers of relatively thick cardboard spaced apart about one-half inch, the space therebetween being filled with some kind of plaster such as gypsum or similar material. In order to apply wallpaper to walls composed of such materials the walls are first covered with a lightweight fabric known as decorators canvas and the wallpaper is then pasted to this canvas which proxides a flexible base for the paper and tends to prevent it from cracking or splitting. The canvas is attached to the gypsum or plaster board walls by driven fastenings, such as tacks, staples and so forth which are usually driven by hand with a hammer or other driving tool.

When single shank fiat headed tacks are used in this work the workmen use a magnetic hammer, that is, a hammer having a magnetized head which attracts or pulls the flat head of the tack against the driving face of the hammer and holds it there with the shank of the tack projecting outwardly in position to be driven. The tack is then driven flush with the surface vof the work by a s5 single blow of the hammer, thus making the operationquiek and easy to execute for those skilled in the trade. It has been found, however, that single shank tacks are not satisfactory for this work because they have very little holding power in gypsum or plaster board and when driven they disrupt or break up the relatively soft or fragile structure of the gypsum material forming the wall board.

Moreover, ordinary U-shaped staples having the usual thick, narrow crossbar and depending legs are entirely unsatisfactory for this work because they have insufficient holding power in this gypsum board and similar materials and because they likewise disrupt the structure of the gypsum board. In addition, ordinary staples cannot be used with a magnetized hammer because they have no flat head or driving surface like tacks to be attracted and held against the magnetized head of the hammer so that the legs of the staple will project outwardly in position to be driven. Furthermore, it is impractical to attempt to use ordinary staples by positioning and holding them in position with the fingers until driven. While special types of staples have been used heretofore in this work, their use has always required the provision of special tools or equipment, such as automatic hammers or similar tools, which involves considerable expense more particularly when it is realized that such tools can generally be of use only for the single purpose intended. What is of equal importance in this line of work, moreover, is the fact that the special equipment necessary for use with these special types of staples calls fora radical change in the long established method or technique of the workmen in'applying the canvas to the gypsum board walls because th workmen have long been accustomed to use a magnetized hammer and have become skilled in its use so thatany attempt to change this usual procedure upsets the long-established practice of the workmen and has a tendency to disrupt or create disturbances in the trade.

To this end the invention provides, in accordance with one feature, an improved fastening member or staple comprising a bar portion and a pair of relatively thick, rigid legs depending therefrom, the legs converging inwardly toward each other a relatively small amount. The bar .portion of the staple is of substantially greater width than the legs and it is much thinner in cross section than said legs up to its point of union with the legs so that the connections it provides with the legs are of substantially greater flexibility than ,enyother portion of the staple, thereby permitting the legs to converge in the work piece until their ends substantially meet in the material into which the staple is inserted, thereby locking the staple in the material and greatly increasing its holding power and resistance to withdrawal.

As herein illustrated, the legs of the staple initially converge inwardly toward each other only a small amount and the thin flexible connections with the bar portion permits further converging of the legs when the staple is driven. Moreover, this converging action takes place without damaging the material into which the staple is driven as, for example, in the case of plaster board, by breaking up or crumbling such material.

As illustrated, the wide bar portion of the staple enables it to engage a relatively large area of the material to be fastened, prevents the bar portion from cutting through the material when the staple is driven, and also renders the connections with the legs sufficiently inflexible transversely of the bar portion to prevent lateral deflection of the legs during their converging action. The .bar portion of the staple, as herein illustrated, is also substantially flat in cross section so that it will provide the staple with a good driving surface or head particularly adapted for use, for example, with the so-called magnetic hammer, that is, one having a magnetized head or driving surface especially convenient for use in the type of work referred to. The extreme thinness of the .bar portion, besides rendering the connections with the legs relatively yielding or flexible, also permits the bar portion to be driven substantially flush with the surface of the materials being fastened, as for example, where canvas is being secured to wall board such as gypsum or plaster board. As herein illustrated, the thin, fiat bar portion of the staple is preferably oval in shape or periphery which provides relatively large surfaces for engaging the material fastened and for co-operating with the hammer or other driving tool.

With the above and other objects and features in view, the invention will now be described with reference to the accompanying drawing and will thereafter be pointed out in the claims.

In the drawing,

Fig. 1 is a greatly enlarged perspective view of one side of the fastening member or staple forming the subject-matter of the invention;

Fig. 2 is an elevation of the opposite side of the staple;

Fig. 3 is a plan view of the staple;

Fig. 4 is a side elevation partly in section showing the condition of the staple after it has been driven into materials to be fastened thereby;

Fig. 5 is a side view similar to Fig. 4 but with a part of the bar portion and a leg of the staple shown in cross section; and

Fig. 6 illustrates how the staple may be carried by a magnetized hammer for insertion into the work.

The improved fastening member or staple I0 of the present invention is illustrated on a greatly enlarged scale in Figs. 1 to 3 of the drawing and, as shown in those figures, comprises a bar or body portion I2 having a pair of legs or shanks M depending downwardly therefrom. The legs M depend from the opposite ends of the bar portion I2 and are provided at their lower ends with piercing points l6 produced by inclined diagonal cuts I! which extend considerable distances upwardly from the ends of the legs. Beyond or above the points Hi, the legs M are substantially rectangularin shape and, as shown in the drawing, are relatively thick in cross section as compared with the bar portion l2 of the staple. Moreover, although the legs are practically straight throughout their lengths, they are arranged initially to incline or converge inwardly toward each other a relatively small amount, as shown in Figs. 1 and 2, the angles between the bar portion and the legs being slightly acute.

The inclined cuts or bevels [1 which produce the points IE on the staple legs I 4 are located at opposite sides of the legs with respect to each other or, in other words, the inclined cut on one leg is on the forward side of such leg when the bar portion I2 is positioned crosswise, as shown in Figs. 1 and 2, and the inclined cut on the opposite leg is on the rear side of the leg, the points l6 of the staple, however, being substantially in line with each other crosswise of the staple, or lengthwise of its bar portion. Since the inclined cuts I! are not located on the outside surfaces of the legs or those most remote from each other, that is, the surfaces that form continuations of the top side of the bar portion l2, the surfaces I! have no tendency when the staple is driven to cause the legs to converge inwardly or toward each other a greater amount than their initial convergence. Moreover, it will be observed that the sharp edges I 5 of the legs, which extend from the points It upwardly, are inclined at the same angles and are parallel to each other so that these edges, which are produced by the inclined cuts I! passing diagonally through the legs, likewise have no tendency to cause the legs to converge or move together when the staple is driven.

The bar portion I2, which forms the driving head of the staple, is substantially fiat in cross section and, in plan view (Fig. 3), its periphery is substantially oval in shape except at its opposite ends H where the legs join the bar portion, which ends project outwardly from the bar portion. The bar portion I2 is also much greater in width than the legs l4 except where the legs join the bar portion, as is clearly shown in Figs. 1 and 3. Moreover, this wide fiat bar portion or driving head I2 is extremely thin in cross section up to its point of union with the legs l4 and these connections are thus rendered considerably more flexible than any other portion of the staple so that they can bend or flex under a sufiicient blow without breaking.

In actual size, as shown approximately in Fig. 6, the legs of the staple, above the pointed por tions [6, might be, for example, thirty-five to forty thousandths of an inch thick in cross section and the bar portion by comparison might be ten or twelve thousandths thick heightwise of the staple. The angles upon which the legs M are inclined inwardly with respect to the bar portion l2, as stated, are relatively slight and, in the present instance, have been formed by bending the legs inwardly until their points are about ,6 of an inch apart. The foregoing dimensions, however, are merely illustrative of the relative proportions of the staple and should not be regarded as limiting the invention since the advantages thereof could be obtained with somewhat different dimensions or proportions provided the features disclosed herein were also included.

As indicated above, the staple I 0 is adapted for use in securing layers of material together, as, for example, in securing a layer or sheet of decorators canvas to wall board material such as gypsum board which is used extensively in some localities for forming the interior walls and ceilings of the rooms of houses. Accordingly, the staple has been illustrated herein, by way of example, for this use. In Fig. 4 the staple Iii is shown on an enlarged scale driven into a layer of gypsum board IB to secure thereto a sheet of canvas 20, this gypsum board, as is well known, comprising spaced parallel outer layers 22 of strong fibrous material, such as heavy cardboard, between which is located plaster or similar material 2 1 which forms the commercial product. After the canvas is attached the wallpaper 23 may be applied in the usual manner by paste.

In this kind of work the staple is usually driven by a single blow of a hammer 26 which, as illustrated in Fig. 6, is preferably provided with a head 28 the driving portion of which comprises a horse-shoe magnet having two arms or poles 29, 3| which attract or pull the bar portion l2 of the staple against the driving surfaces of these poles and hold the staple in position to be driven with its bar portion spanning the poles of the magnet and its legs projecting outwardly there from. Obviously the wide fiat bar portion or driving head I? of the staple permits this magnetized hammer to be used whereas, if the bar portion were the same width as the legs, as is the case with ordinary staples, a magnetized hammer could not be used because the legs of such a staple would be pulled against the hammer as well as the bar portion and therefore would not project outwardly in a position to be driven as they do in the case of the large flat driving head l2, as illustrated in Fig. 6.

The staple iii is driven by the hammer 26 by a single blow. As illustrated in Fig. 4, the thin flat bar portion l2 may be readily driven so that its outer surface is substantially flush with the outer surface of the sheet of canvas 2! which is being attached to the gypsum board I8. Moreover, the relatively large area engaged by the bar portion 52 prevents it from cutting through the canvas or other material which is being fastened.

As the staple is driven the legs Hi continue to converge while passing into the material until their lower or pointed ends 16 substantially meet to form a triangular lock in the material, as shown in Figs. 4 and 5, this result being obtained by reason of the initial inclination or convergence of the legs I l and also because of the flexibility of the connections of the legs with the thin driving head l2 which permits them to yield or bend under the force of the hammer blow in such a manner that the legs I4 will converge increasingly as they enter the material.

This increasing converging action of the legs of the staple upon being driven until they form a lock in the material may be further explained as follows. The legs enter the material at points spaced apart from each other a distance somewhat less than the width of the bar portion l2. Because of their slight initial inclination or convergence, the normal tendency of the legs would be to remain or continue on these slight angles as they pass into the material. However, as the upper portions of the legs, which extend gradually farther apart, descend into the material, these wider portions crowd or compact the material engaging their outer or remote sides and thus create a pressure against the legs which increases progressively as the wider portions of the legs enter the material, with a corresponding decreasing of pressure against the inner or adjacent surfaces of the legs.

Since the thin bar portion i2 is relatively flexible and the joints or connections where the legs meet it can yield or bend a little, this increased pressure of the compressed material against the outside surfaces of the legs forces the legs to converge or toe inwardly more and more as the legs pass into the material and this compressing action increases until, when the staple is fully driven and its bar portion is fiush with the surface of the material, the lower or pointed ends of the legs have converged until they are substantially in engagement with each other, thereby forming a mechanical lock which, it might be pointed out, is frictional as well as mechanical because of the pressure of the material against both sides of the legs.

Fig. 5 illustrates in cross section at 21 one end of the bar portion where a leg I4 joins it and it will be seen from that figure that the relatively thin connection or joint 2| between the leg and the bar portion will permit such bending or flexing without distorting the flat driving head. Fig. 4 illustrates also the manner in which the legs of the staple penetrate such material, for example, as gypsum or wall board and increase their converging action while passing through the wall board without damaging the material by breaking up its structure and causing it to crumble. It will be clear from this figure, moreover, that since the ends of the legs Id practically meet in the material, these legs form an eifective lock for holding the staple firmly in the material rather than relying upon friction alone for its holding power, as is the case with single shank tacks or ordinary staples the legs of which are substantially perpendicular to the bar portion of the staple. Accordingly, the holding power of the present staple is greatly increased even in such relatively soft materials as plaster or gypsum board and its resistance to withdrawal is likewise substantially increased. If the frictional hold of the staple is impaired as time passes, the mechanical lock remains to provide the holding power for the staple.

Since the legs Id of the staple are relatively thick and strong, and are attached to the bar portion 12 by relatively wide though thin and flexible connections, as shown in Figs. 3 and 5, the attachment of the legs to the bar portion is sufliciently strong to resist breakage from corrosion or other causes. The width of the thin, flexible connections of the legs with the bar portion also renders them sufficiently inflexible transversely of the staple to prevent any lateral deflection of the legs during their converging movement when driven. Moreover, as mentioned above, the wide fiat oval bar portion or head I2 provides a surface between the legs of the staple which will engage a relatively large area of the material to be fastened, in the present case, for example, the sheet of canvas 29, thereby securing the canvas more firmly to the gypsum board and reducing to a minimum the chances of the bar portion cutting through the canvas when the staple is driven, as sometimes happens in this work with ordinary staples having bar portions of the same width or thickness as their legs. The outer or top surface of the oval bar portion, as stated, provides a large fiat driving head on the staple which may, of course, be used with an ordinary hammer but which, as illustrated in Fig. 6, is particularly well adapted for use with a magnetized hammer with which ordinary staples could not be used for the reason pointed out above.

It will be understood that the novel staple of the present invention is not limited to use in the particular kind of work illustrated herein or for fastening together materials of the kind herein disclosed since the staple could obviously be used with equally beneficial results and advantages in other kinds of work or with other kinds of material.

Having thus described our invention, what We claim as new and desire to secure by Letters Patent of the United States is:

1. A fastening member comprising a staple having a pair of relatively thick, rigid legs which are substantially straight but converge inwardly toward each other a relatively small amount, said legs being flexibly connected together by a relatively wide, flat, oval-shaped bar portion which is much thinner than said legs up to its point of union with the legs and is of suflicient size to cover a relatively large area, said bar portion providing connections between said legs which are of substantially greater flexibility than any other portion of the staple and will thus permit the legs to converge readily toward each other when inserted into a work piece without any tendency to fracture the material of the work piece, but said connections being also sufficiently inflexible transversely of the bar portion to prevent lateral deflection of the legs during their converging movement.

2. A fastening member comprising a staple having a bar portion and a pair of legs depending from the opposite ends thereof, said bar portion being relatively wide, flat and substantially oval in shape to cover a relatively large area, and said legs being relatively thick, rigid and inflexible and being substantially straight lengthwise but converging inwardly toward each other at relatively slight angles, said bar portion being much thinner than said legs up to its point of union with the legs and providing connections between the legs which have greater flexibility than the other portions of the staple to permit the legs readily to converge toward each other increasingly when inserted into a work piece without exerting sufiicient pressure against the work piece to fracture the material thereof, said connections being also sufficiently inflexible transversely of the bar portion due to the substantial width of said portion to prevent deflection of the legs laterally of the staple during their converging action, thereby causing the legs to converge inwardly in the same plane widthwise of the staple, the initial convergence of said legs being such that when driven fully into the work piece they will be caused to converge suificiently toward each other substantially to meet in said work piece to form a triangular lock therein.

3. A fastening member for use in relatively soft, breakable material comprising a staple having a bar portion and a pair of legs depending therefrom, said bar portion being wide, flat and substantially oval in shape to cover a relatively large area, and said legs being thick, straight and rigid enough to remain straight when driven into a work piece, said legs initially converging inwardly toward each other a relatively small amount from the bar portion, said bar portion being much thinner than said legs up to its point of union with the legs and thereby forming connections with said legs of such flexibility that the legs will readily converge inwardly toward each other increasingly when inserted into a work piece of relatively soft, breakable material without any tendency to break or fracture said material, but said connections being also of such width transversely of the bar portion as to render them substantially less flexible in a transverse direction, thereby preventing the legs from being deflected laterally out of their normal plane during their converging movement so that the legs will be caused substantially to meet in said soft, breakable material by their increasing converging action to form a mechanical lock in the work piece.

IRVIN MAXWELL REID. CHARLES H. JOHNSON.

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