Patent Application
20070193208
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.
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'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 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.
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 substrate has embossings formed therein. The adhesive composition is bonded to the fasteners and maintains them in the substantially parallel arrangement in the row.
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.
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.
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.
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.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.
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:
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
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.
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.
Advantageously, the embossings 24 present a tape 18 with a thickness t18 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.
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.
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.
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.
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
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.
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−avgemb.)/ avg.pl]×100%=18% difference.
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.
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
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.
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.
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.
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.
As seen in
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 (
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.
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.
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.
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.
