Abstract:
A fastener assembly for use in a fastener driving tool includes a row of fasteners arranged substantially parallel to each other and a strip having 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 substrate has embossings formed therein. The adhesive composition is bonded to the fasteners and maintains them in the substantially parallel arrangement in the row. A method for making the embossed strip is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention pertains to collated fasteners. More particularly, the present invention pertains to a collated nail strip formed with an embossed tape, for use in a fastener driving tool.  
         [0002]     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.  
         [0003]     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.  
         [0004]     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.  
         [0005]     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.  
         [0006]     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 includes a tape that has a thickness several times greater than plain tape without increasing the paper thickness or weight. 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  
       [0007]     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.  
         [0008]     The substrate has an elongated dimension extending generally in the direction of the row of fasteners. The substrate has embossings formed therein. The adhesive composition is bonded to the fasteners and maintains them in the substantially parallel arrangement in the row.  
         [0009]     The embossings in the strip reduce the tendency of the nail strip to corrugate and decreasing the shear required to properly separate the nail from the strip and without substantially increasing the size of the tape or the amount of adhesive.  
         [0010]     The embossings provide a resulting tape thickness that is several times greater than plain (non-embossed) tape. The embossing pattern produces a 3-dimensional geometry that increases the rigidity of the tape and increases the overall thickness of the nail strip.  
         [0011]     A present strip is formed having diamond pattern embossings. The diamond pattern is a repeating diamond pattern that defines major and minor axes. The major axis can be formed parallel to an edge of the strip. Alternately, the fasteners are positioned at an angle relative to the elongated dimension of the strip and the major or minor axis is positioned substantially parallel to the fasteners, or at an angle such as 90 degrees. The strip can include ribs extending between embossings at the major or minor axes.  
         [0012]     Various alternate embossings patterns can be used, such as a rectangular pattern, a hexagonal (e.g., honeycomb) pattern, a circular pattern or some combination thereof that allows plastic material to be moved (or introduced) into the rib sections (the embossings). Embossing depths can vary to provide a desired overall tape or nail strip thickness.  
         [0013]     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  
       [0014]     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:  
         [0015]      FIG. 1  is a plan view of one embodiment of a nail strip having a paper tape collation system having an embossed tape pattern embodying the principles of the present invention;  
         [0016]      FIG. 2  is a plan view of a second embodiment of the paper tape collation system,  FIG. 2A  being a second view of this embodiment;  
         [0017]      FIG. 3  is an enlarged view of an isolated section of the embossed diamond patterns;  
         [0018]      FIG. 4  is a schematic illustration of a 45 degree square embossing pattern  
         [0019]      FIG. 5  is a schematic illustration of a 45 degree square embossing pattern with an alternating integrated brace;  
         [0020]      FIG. 6  is an illustration of a cross-section of an exemplary section of embossed tape;  
         [0021]      FIG. 7  is a schematic of an alternate pattern in which the embossing lines are offset from one another at the line junctures;  
         [0022]      FIG. 8  is an illustration of yet another alternate pattern in which the embossing is a single longitudinal embossing; and  
         [0023]      FIG. 9  is an illustration of a testing device that was used to compare the shear required for an embossed tape strip to that required for a plain tape strip.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     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.  
         [0025]     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.  
         [0026]     Referring now to the figures and in particular to  FIG. 1  there is shown a nail strip  10  having a paper tape collation system  12  with an embossed tape pattern  14  embodying the principles of the present invention. The strip  10  includes a plurality of fasteners  16 , such as the illustrated nails disposed parallel to one another. As will be appreciated by those skilled in the art, the illustrated nails  16  are full head nails, rather than D-head nails. Accordingly, the nails  16  provide increased holding characteristics (due to the increased surface area of the nail  16  head). However, it will be appreciated that using full head nails  16  requires that the strip  10  is fabricated with a slightly greater distance between the (axes A 16  of the) nails  16  to accommodate the larger nail  16  heads.  
         [0027]     The nails  16  are collated and held to one another by tape strips  18 . A strip  18  can be disposed along each side of the nail strip  10 . The tape strips  18  are adhered to the outer peripheral sides  20  of the nails  16  by an adhesive  22 . Any of a variety of known adhesives  22  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  22  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.  
         [0028]     The paper tape strips  18  are formed with the embossed pattern  14  therein. One pattern, a diamond pattern, has diamond-shaped embossings  24 , each having a major axis (as indicated at  26 ) and a minor axis (as indicated at  28 ). The diamond pattern can be a repeating diamond pattern.  
         [0029]     Advantageously, the embossings  24  present a tape  18  with a thickness t 18  that is several times greater than that of a plain tape. The actual thickness will of course depend upon the type of embossing and the depth of the embossing. The embossing  24  produces a ribbed pattern or profile having a 3-dimensional geometry that increases the rigidity of the tape  18 . This reduces the opportunity for the strip  10  to corrugate, particularly as the distance between the nails  16  increases.  
         [0030]     The embossed tape  18  provides another advantage that may be less apparent. Nail strips  10  are used in a variety of nail guns, and conversely, nail guns can use a variety of different sizes of nails. The widths of the magazines of the nail guns vary to accommodate these different size nails. Accordingly, there may be little space between the nail strip  10  and the magazine wall or there may be a fairly sizable distance between the strip  10  and the wall.  
         [0031]     It will be appreciated that it is desirable for the thickness of the strip  10  to as large as possible without ering so large as to bind on the walls of the magazine. This prevents side-by-side overlapping of nail strips  10 . As such, there is a desire to increase the overall nail strip  10  thickness, without increasing other characteristics, such as the shear force required to separate a nail  16  from the strip  10 .  
         [0032]     The present embossings  14  provide this increased thickness (as well as increased rigidity) without a commensurate increase in some of the other, non-desired characteristics. For example, it has been found that because the amount of adhesive (plastic) is not increased, the required shear has not increased. In fact, it was found that the force required to shear the nail  16  from the strip  10  actually decreased compared to a plain tape strip.  
         [0033]     A weight impact fixture  200  was used to determine the comparative differences in force required to separate a nail from a plain strip and an embossed strip in accordance with the principles of the present invention. The fixture  200 , illustrated in  FIG. 9  includes an exemplary nail gun magazine  202  mounted to a stand  204 . A graduated tube guide  206  carries a 4 ounce weight  208  with a driver blade  210  mounted to a bottom end. The weight  208  and driver blade  210  were raised to a designated height and “dropped” so that the blade  210  struck the nail  16  head.  
         [0034]     The height to which the weight  208  was required to be raised in order to separate the nail  16  from the strip  10  was measured over 12 drops for the embossed tape strip and 11 drops for the plain tape strip. In testing, a plain strip having a thickness of 0.023 inches and a diamond embossed strip, also having a thickness of 0.023 inches were subject to drops to shear the nails  16  from the strip  10 . The heights to shear were measured. The results are provided in Table 1, below.  
                                           TABLE 1                           DROP HEIGHT TO SHEAR                Embossed Tape   Plain Tape           Drop Height   Drop Height       Drop Number   (Inches)   (Inches)                    1   39   53       2   39   48       3   39   48       4   39   48       5   42   43       6   39   48       7   39   48       8   39   48       9   36   48       10    36   43       11    39   48       12    42   —       Average   39   47.5                  
 
         [0035]     As can be seen from the results, the heights for the embossed tape were consistently less than that required to shear the plain tape. The percent difference was calculated as: 
 
% diff=[(avg .pl −avg emb. )/ avg .pl ]×100%=18% difference. 
 
         [0036]     This represents a substantial decrease in the shear force required to separate the nails from the strip in the embossed tape strip compared to the plain tape strip.  
         [0037]     In the exemplary diamond pattern, the tape  18  can be formed with the major axis  26  or minor axis  28  parallel to the edges  30  of the tape  18 , e.g., so that the diamond pattern  14  falls within the edges or margins  30  of the tape  18 . Alternately, as seen in  FIGS. 2 and 2 A, the tape  118  can be formed with the diamond pattern  114  on a bias relative to the length L 118  of the tape  118 . In such an arrangement, the major axis  126  can be oriented transverse, and preferably perpendicular to the longitudinal axis A 16  of the nail  16 . In this manner, the minor axis  128  extends parallel to the shear line  132  that is formed as the nail  16  is separated from the strip  10 .  
         [0038]     The novel embossings  24 ,  124  in the tape  18 ,  118  provide a number of advantages over known flat or planar tape strips. First, the embossings  24 ,  124  provide resistance to bending of the tape  18 ,  118  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 diamond pattern  24 ,  124  provides points at which the tape  18 ,  118  will tend to shear, or frangible regions ( 32 ,  132 ), to facilitate separation of the nail  16  as it is driven from the remainder of the strip  10 . Thus, the embossed pattern  14 ,  114  provides strength in the compressive direction (to prevent corrugation) and provides separation lines  32 ,  132  along which the tape  18 ,  118  can be torn.  
         [0039]     As seen in FIG(S).  3  (and  5 ), a reinforcing rib  34  (and  434 ) can be formed in the tape  18 ,  118  along the major axis  26 ,  126  of the diamond embossing  24 ,  124 . The rib  34  provides additional rigidity and strength to the tape  18 ,  118  to further reduce the potential for corrugation.  
         [0040]     In a present embossed tape  18 ,  118 , a ¾ inch wide kraft paper tape substrate  36  having the diamond pattern embossing  24 ,  124  was formed. The paper  36  was a 30 lb. kraft paper with thickness of about 0.003 inches (3 mils). The diamonds  24 ,  124  each had a minor axis  28 ,  128  dimension of about 0.064 inches and a major axis  26 ,  126  dimension of about 0.099 inches. The adhesive layer  22  was a heat reactive high density polyethylene based material applied to the substrate  36  to a thickness of about 19 mils after embossing.  
         [0041]     In the illustrated strip  10 , the nails  16  are positioned at an angle α of about 20 degrees to the transverse direction  38  of the strip  18 ,  118 ; however, other angles α 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 can be “packed” in less linear (tape measured) distance as the angle α decreases. As such, the number of nails in a 20 degree collation is greater than the number of nails  16  in a 30 degree collation system.  
         [0042]      FIGS. 4-5  illustrate two square, 45 degree embossing patterns  314 ,  414 , a first  314  in which the embossing lines or creases  324  are on 0.130 inch centers and the embossing lines have a width of about 0.020 inches (20 mils). The embossing pattern  314  is a 45 degree pattern and the machine direction is illustrated by the arrow at MD. The depth of the embossings  324  are at, for example, about 16 mils to 22 mils. The pattern  414  in  FIG. 5  illustrates a 45 degree pattern  414  with the embossing lines or creases  424  on 0.130 inch centers and having a width of about 0.020 inches (20 mils), with depths of about 16 mils to 26 mils. The pattern  414  of  FIG. 5  also includes the brace  434  in an alternating pattern that extends corner to corner of the squares in the machine direction MD. The braces  34  and  434  provide additional rigidity to further reduce the opportunity for the strip  10  to corrugate.  
         [0043]     As seen in  FIG. 7 , the pattern  514  can be formed such that the embossing lines  524  are not straight at the junctures  526  (e.g., not collinear), but rather are offset from adjacent lines to further enhance the ability to effectively (e.g., cleanly) shear the tape, while maintaining the desired longitudinal rigidity of the tape.  
         [0044]     Various embossing patterns have been successfully formed, including square embossing patterns with depths of 25 and 35 mils, a square embossing pattern with a depth of 25 mils and with alternate bracing ( FIG. 5 ), a canted diamond pattern with a 23 degree cant and depth of 35 mils, a reinforced (braced) canted diamond pattern with a 23 degree cant and depth of 35 mils and a canted diamond pattern with a 67 degree backside cant and a depth of 35 mils. The angle of cant is the measured as the angle between the diamond major axis and the edge of the tape strip. Still another tape  614  is illustrated in  FIG. 8  in which one or more longitudinal embossings  624  extend along the length or along the longitudinal axis of the  614 .  
         [0045]     It will also be appreciated by those skilled in the art that the “paper” tape substrate  36  can be formed from materials other than paper or paperboard-based materials, such as polyester and other film forming polymers or fabrics, such as cloth. In all such strips, the embossing  14 ,  114 ,  314 ,  414 ,  514 ,  614  can be formed in the strip during manufacture, such as following an extrusion step in which adhesive extruded onto the tape (to form the lamination) or later in a post-manufacture process. It is also anticipated that the substrate is provided, the embossings formed and the adhesive applied. In a present tape and process, the embossings are formed after application of the adhesive to the substrate, and are formed to a depth of about 16 mils to about 35. In making the nail strip  10 , the tape  18  is applied to heated nails  16  and introduced to a roller to press the tape  18  to the nails  16 . In one method of making the strip  10 , the tape  18  is pressed with a greater force at the edges than in the center of the tape  18 .  
         [0046]     It has been found that the embossed tape nail strip  10  has the additional advantage of reducing the amount of debris that is generated upon actuation of the nail gun. Strips of nails having an equal number of nails were fired from a nail gun and the debris generated was collected. The strips included a plastic collation, a non-embossed (plain) tape strip and an embossed tape strip. The debris from each was weighed. The plastic collation generated 4.318 grams of debris per strip of nails, the plain tape generated 0.5586 grams of debris and the embossed tape generated 0.2137 grams of debris per nail strip. It will be appreciated that it is more advantageous to have a lesser amount of debris generated.  
         [0047]     The embossings  14 ,  114 ,  314 ,  414 ,  514 ,  614  are not limited to the illustrated repeating diamond pattern  24 ,  124 ,  324 ,  424 ,  524 . In fact, many other embossing shapes and profiles are anticipated as set forth above, such as, cruciform shapes, hexagonal shapes, octagonal shapes and round shapes. These and other shapes can be used to form the embossed pattern  14 ,  114 ,  314 ,  414 ,  514 ,  614  and are all within the scope and spirit of the present invention.  
         [0048]     All patents referred to herein, are incorporated herein by reference, whether or not specifically done so within the text of this disclosure.  
         [0049]     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.  
         [0050]     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.