Abstract:
A fastener assembly for use in a fastener driving tool is formed as a row of fasteners arranged substantially parallel to each other and a supporting strip. The strip has a supporting substrate and an adhesive composition thereon. The supporting substrate has an elongated dimension extending generally in the direction of the row of fasteners. The supporting substrate defines upper and lower edges, at least one of which has a scallop formation therein between the fasteners. The scallop formation defines a 3-dimensional profile to stiffen the fastener assembly. The adhesive composition bonds to the fasteners to maintain the fasteners in the substantially parallel arrangement in the row. A method for making the assembly is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to collated fasteners. More particularly, the present invention pertains to a collated nail strip formed with a scalloped-edge tape, for use in a fastener driving tool. 
     Fast-acting fastener driving tools are in widespread use in the construction industry. For use in these tools, the nails are assembled in strips that are inserted into a magazine of the tool. The strips are flat and the nails or other fasteners are held parallel to one another. The nails are assembled in a staggered or stepped manner such that the major axis of the nail forms an angle to the longitudinal direction of the strip. In presently known collated nails, the angle is about 10 degrees to 40 degrees and preferably between 15 degrees and 25 degrees. An in-depth discussion of such fasteners is provided in U.S. Pat. No. 5,733,085, to Shida, which is incorporated herein by reference. 
     Presently known collated nails are assembled using tape strips or an extruded plastic material. The plastic (or polymer) in the plastic-formed strips is cooled and hardens to hold the nails in the strip form for use in the tool. The tape strips are formed from a kraft paper or other paperboard material having a plastic (polymer) adhesive on a surface thereof that is heated on contact with hot nails and, as it cools, adheres to the nails. 
     The tape strips have the advantage of minimizing the debris that is formed as the tool is actuated and the nails are driven into the material (typically wood) to be fastened. However, with the tape strip it has been observed that the strip can flex and tend to advance on each other. This is a condition known as corrugation and has been found to be one of the greatest causes of tool jamming and fastener failure, and increases as the nails are spaced farther apart. 
     One way in which the corrugation problem has been addressed was to use a thicker tape with a relatively large quantity of adhesive material on the tape (to secure to the nails). However, it was found that as the strip&#39;s resistance to corrugation increased, the force required to separate the nail from the strip and to shear the tape, e.g., resistance to shear, increased as well. As such, nails tended to remain affixed to the tape and jamming of the tool occurred. 
     Accordingly, there is a need for a paper tape collation system for strip-formed fasteners that reduces the tendency for the nail strip to corrugate in the tool magazine. Desirably, such a system reduces the tendency to corrugate without increasing the shear required to properly separate the nail from the strip in a predetermined manner as the tool is actuated. More desirably, such a system reduces the tendency to corrugate without substantially increasing the size of the tape or the amount of adhesive. 
     BRIEF SUMMARY OF THE INVENTION 
     A fastener assembly is for use in a fastener driving tool. The assembly includes a row of fasteners arranged substantially parallel to each other and a strip having a supporting substrate and an adhesive composition thereon. The assembly forms a collating nail strip. 
     The substrate has an elongated dimension extending generally in the direction of the row of fasteners. The adhesive composition bonds the supporting substrate to the fasteners and maintains them in the substantially parallel arrangement in the row. The supporting substrate defines upper and lower edges, at least one of which has a scallop formation therein between the fasteners. The scallop formation defines a 3 dimensional profile to stiffen the fastener assembly. The adhesive composition bonds to the fasteners to maintain the fasteners in the substantially parallel arrangement in the row. 
     In a present assembly, strips are present on both sides of the row of fasteners to define opposing strips and the upper and lower edges of both strips have the scallop formation therein. A central portion of the strip, between the upper and lower edges is planar, that is, not scalloped. The scallop formation can be formed inwardly about 20 mils from a plane of the strip. 
     A method for making the fastener assembly includes the steps of arranging a plurality of fasteners in a row parallel to one another, heating the plurality of fasteners to elevate the temperature of the fasteners, applying a strip having a substrate and an adhesive thereon to the heated fasteners along a side of the row, the strip having an upper edge and a lower edge, applying pressure to the strip to adhere the strip to the fasteners and forming a scallop formation in the strip at the upper or lower edge between the fasteners and cooling the strip to form the fastener assembly. 
     These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
         FIG. 1  is a plan view of one embodiment of a nail strip having a paper tape collation system having a scalloped upper and lower edges embodying the principles of the present invention; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 1 ; and 
         FIG. 4  is an edge view of an exemplary molding wheel used to form the scalloped edges. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
     It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
     Referring now to the figures and in particular to  FIG. 1  there is shown a nail strip  10  having a paper tape collation system with scalloped edges embodying the principles of the present invention. 
     As will be appreciated by those skilled in the art, the illustrated nails  12  are full head H nails, rather than D-head nails. Accordingly, the nails  12  provide increased holding characteristics (due to the increased surface area of the nail head H). However, it will also be appreciated that using full head H nails  12  requires that the strip  10  is fabricated with a slightly greater distance d 12  between the (axes A 12  of the) nails  12  to accommodate the larger nail heads H. 
     The nails  12  are collated and held to one another by tape strips  14 . A strip  14  can be disposed along each side of the nail strip  10  as seen in  FIG. 3 . The tape strips  14  are adhered to the outer peripheral sides  16  of the nails  12  by an adhesive  18 . Any of a variety of known adhesives can be used, such as extrudable polyolefins, such as maleic anhydride modified, and others, such as, but not limited to polyethylene (especially high density polyethylene), polypropylene, copolymers of ethylene with other alpha olefins (for example, linear low density polyethylene) copolymers of propylene with other alpha-olefins, copolymers of ethylene with ethylenically unsaturated esters and their derivatives (for example, ethylene vinyl acetate), and mixtures including any of these polymers. The adhesive can be applied by extrusion, coextrusion, spraying or a variety of other known application processes. It will be appreciated by those skilled in the art that a lamination formed from multiple layers of similar or dissimilar materials can be used to form the tape to achieve a desired result. 
     The strips  14  have scalloped upper and lower edges as indicated at  20 . The scalloped edges  20  are formed by pressing the tape  14  material, at the edges  22 , into the space  24  between the nails  12 , or pressing the strips  14  on either side of the nails  12  in toward one another. 
     Advantageously, the scallop formations  20  present a tape  14  with an effective thickness t 14  (see  FIG. 3 ) that is greater than that of a plain tape. The effective thickness t 14  is that measured so as to take into account the inward movement of the tape  14 . That is, the effective thickness t 14  is a linear measurement that is measured from the substrate outside surface of the tape  14  to the innermost surface of the tape  14 , as seen in  FIG. 2 . The scalloped edges  20  produce a pattern or profile having a 3-dimensional geometry that increases the rigidity of the strip  10 . This reduces the opportunity for the strip  10  to corrugate, particularly as the distance d 12  between the nails  12  increases. In a present strip  10 , in a tape  14  having a planar thickness of about 0.003 inches (3 mils), the scallop formation  20  is pressed or urged inward a distance of about 0.020 inches (20 mils). 
     The novel scalloped edges  20  in the tape  14  provide a number of advantages over known flat or planar tape strips. First, the scalloped edges  20  provide resistance to bending of the tape  14  per se, and, when forming part of the nail strip  10 , help to reduce the tendency of the nail strip  10  to corrugate. In addition, the scallop formations  20  can provide points, as indicated at  26 , at which the tape  14  will tend to shear, or frangible regions, to facilitate separation of the nail  12  as it is driven from the remainder of the strip  10 . Thus, the scalloped edges  20  provide strength in the compressive direction (as indicated by the arrow at  28 ), to prevent corrugation and also to provide separation lines  26  along which the tape  14  can be tom. 
     As is depicted in  FIG. 3 , as the tape  14  is pressed around the shank of the nail  12 , the adhesive  18  moves with the tape  14  and extends or flows around a portion of the nail  12 . This tendency to extend around the nail  12  (or to partially envelope the nail  12 ) further enhances the resistance to corrugation by increasing the area over which the adhesive is present on the nail and the area over which the adhesive  18  adheres the tape  14  to the nail  12 . 
     In a present strip  10 , a ¾ inch wide tape  14  of 30 lb. kraft paper with thickness of about 0.003 inches (3 mils) was formed. The adhesive  18  was applied by coextrusion onto the substrate  14 . The adhesive layer  18  was a heat reactive high density polyethylene based material applied to the substrate  14  to a thickness of about 9 to 11 mils. The scallops  20  were formed to a “depth” of about 20 mils. 
     In the illustrated strip  10 , the nails  12  are positioned at an angle a of about 20 degrees to the transverse direction of the strip  10 ; however, other angles a are contemplated for use with the present invention. One of the advantages of the  20  degree collation system is that a greater number of nails  12  can be “packed” in less linear (tape measured) distance as the angle a decreases. As such, the number of nails  12  in a 20 degree collation is greater than the number of nails in a 30 degree collation system. 
     Referring to  FIG. 4 , in order to form the scalloped edges  20 , a molding wheel  102  is used (in use, molding wheels are located above the nails moving along a fabrication line and below the nails moving on the fabrication line to scallop the edge of the tape on both sides of the strip). The molding wheel  102  is formed with a discontinuous helical thread profile  104 . The discontinuity is effected by an open central area  106  in the wheel  102 . As will be appreciated from a study of the figures, the helical formation  104  is present at the edges  108  of the wheel  102  to press or for the scallops  20  in the upper and lower edges  22  (on both sides or tapes  14  of the strip  10 ), while the central area  106  is open or channeled so as to leave the middle section  30  of the tape  14  planar. In a present molding wheel  102 , the threads  104  are formed at an angle β that is about equal to the angle α at which the nail  12  is oriented relative to the tape  14 . 
     One method for making the present strip  10  is to position the nails  12  in a conveyor or other indexing device, heat the nails  12 , apply the tape  14  with the adhesive  18  on the tape  14  onto the heated nails  12  and introduce the nails  12  and the tape  14  to the molding wheel  102  to press the edges  22  of the tape  14  to form the scallops  20  while the adhesive  18  is still at an elevated temperature. 
     It will be appreciated that although the present strip  10  is described as formed from a plain paper strip  14 , other materials, such as polyolefins can also be used or the strip. It will also be appreciated that a patterned strip can be used, such as a strip having an embossed pattern or the like and that all such material and structural modifications are within the scope and spirit of the present invention. 
     All patents referred to herein, are incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
     In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
     From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.