Abstract:
Fastening tool for driving a fastener such as a staple into a substrate a predetermined distance. The tool includes a housing and a driver reciprocally mounted in the housing and moveable with respect to the housing, the driver having a driving surface for engaging a fastener such as a staple. A magazine assembly is associated with the housing for positioning and aligning the fastener in the path of the driver so that when actuated, the driver strikes the fastener and forcibly ejects it from the magazine into the substrate to a predetermined extent so as to adjust or control the holding power of the fastener about the object.

Description:
[0001]     This application is a continuation of U.S. Ser. No. 10/374,353 filed Feb. 25, 2003, the disclosure of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention is directed towards a staple gun or fastener driving or applying tool for driving staples or other fasteners into surfaces. In particular, the present invention relates to a fastening tool where the stroke length of the driver is modified to reduce or eliminate the impact of the fastener on the object being fastened.  
         [0003]     Staple, nail, brad, screw and other fastener-driving applying tools for industrial, commercial and do-it-yourself (DIY) use are well known. Often such tools are used to secure cables, wires, tubing and the like to a substrate such as wood by driving the fastener into the substrate, the fastener thereby surrounding the cable, wire or tubing on three sides. However, the fastener being applied may at the time of application (due to the impact of the fastener) or subsequently (due to wire and/or substrate expansion or contraction over time) penetrate, damage or deform the item being fastened, resulting in an electrical short circuit, leak or other deleterious effect.  
         [0004]     It is often desirable to attach or connect wire or cable, including without limitation high-speed transmission multimedia cable and wire (such as CAT-5 CAT-5e, CAT-6 RG6) and NM Building Wire (also known as “Romex” wire), to substrates using staples, alone or in combination with insulators. The use of these so-called insulators, which may also provide a cushioning function, minimizes the possibility that the staple will penetrate, damage or deform the sheathing on the wire and cause an electrical short or change in current. The use of pre-assembled individual staples and insulators, installed by means of a hammer or similar implement, is conventional. However, this method is slow, tedious, and not very precise.  
         [0005]     Proper installation of staples must meet industry requirements for staple holding power (such as those described in UL specifications) for a wide range of wire types and diameters used in typical residential and commercial construction. However, if the fastener is driven too deeply into the substrate, the fastener can deform the wire, cable, tube or other object being fastened.  
         [0006]     It is therefore an object of the present invention to provide an improved fastener driving tool or gun that ensures consistent, uniform and reproducible driving depth of the fastener into the substrate.  
         [0007]     It is a still further object of the present invention to provide a fastening device that automatically and repeatably drives fasteners to a predetermined depth into a substrate to connect an object thereto.  
         [0008]     It is yet a further object of the present invention to provide a fastening device that is capable of reproducibly driving a fastener into a substrate to a pre-determined depth.  
         [0009]     It is a still further object of the present invention to provide an improved impact pad for a fastener or driving tool or gun that helps minimize or eliminate the possibility that the fastener penetrates, damages or deforms the wire or other object being fastened.  
       SUMMARY OF THE INVENTION  
       [0010]     The problems of the prior art have been overcome by the present invention, which provides a fastening tool for driving a fastener into a substrate wherein the length of the drive stroke of the driver is limited. That is, the path of the drive blade has been modified (relative to conventional staple guns) in order to ensure that the fastener is positioned with respect to the object to be fastened such that desired tension of the fastener on the object to be fastened, the desired holding power of the fastener, and the desired movement of the object to be fastened under the fastener, are achieved.  
         [0011]     The tool includes a housing and a driver reciprocally mounted in the housing and moveable with respect to the housing, the driver having a driving surface for engaging a fastener such as a staple. A magazine assembly is associated with the housing for holding one or more fasteners, and for positioning and aligning a fastener in the path of the driver so that when actuated, the driver strikes the fastener and forcibly ejects it from the magazine into the substrate onto which the object is to be fastened. Suitable fasteners include staples (of various sizes and configurations), nails, brads, rivets, etc.  
         [0012]     In one embodiment, the drive stroke of the driver terminates upon contact with an impact pad of appropriate dimension and composition appropriately positioned in the path of the driver so as to effectively limit the length of the drive stroke to achieve the desired fastening. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is an exploded view of a fastening tool in accordance with the present invention;  
         [0014]      FIG. 2  is a front view of the driver and nosepiece in accordance with the present invention;  
         [0015]      FIG. 3  is a front view of the driver and nose piece with the driver actuated in accordance with the present invention;  
         [0016]      FIG. 4  is a top view of the impact pad in accordance with the present invention;  
         [0017]      FIG. 5  is a cross-sectional view of the impact pad in accordance with the present invention; and  
         [0018]      FIG. 6A  is a front view of an angled fastener in accordance with an embodiment of the present invention;  
         [0019]      FIG. 6B  is a side view of the fastener of  FIG. 6A ; and  
         [0020]      FIG. 6C  is a side view of the fastener of  FIG. 6A  coated with a resin. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Turning first to  FIG. 1 , there is shown one embodiment of the present invention, which is a spring actuated staple gun adapted to drive U-shaped staples housed in a magazine into a surface or substrate. The gun includes a tool body  1  comprised of two stamped nickel-plated sheet metal sides  1 A and  1 B that form a housing there between. Alternatively, the housing could be a cast or molded body. Pivotally fixed to the underside of a handle  2  is a spring-loaded lever assembly C, substantially located in said housing, which includes extended link  2 A and lifter  2 C and allows the handle of the gun to be depressed to actuate the gun and released in order to reset the actuation mechanism. A handle return spring  9  is fixed to the handle  2 . Spring retainer  8  has opposite flanges  8 A,  8 B that align with opposite slots  5 A′  5 B′ in sides  1 A and  1 B of the tool body  1  to fix spring retainer  8  therein. A driver spring pad  5  aligns with the bottom of the driver spring  6  and sits in the body of driver assembly  4 . Impact pad  13  has an impact ledge  14  that aligns with opposite slots  14 A and  14 B in sides  1 A and  1 B of the tool body  1  to fix the same in the housing, and thereby limit the downward movement of driver blade assembly  4  a predetermined amount by preventing the seat  4 A of driver assembly  4  from extending past the top surface of the impact pad  13 . Nose piece  3  secures over the driver assembly  4  as is conventional in the art. Magazine assembly  15  combines with pusher assembly  16  to selectively provide the supply of fasteners into the path of the driver blade.  
         [0022]     Pressing downward on the handle  2  first causes a pair of opposite lips L, L′ of lifter  2 C, which lips engage the driver assembly  4 , to lift the driver assembly  4  upward against the bias of driver spring  6 . Further downward pressure of the handle  2  causes the lips L, L′ to release from the driver assembly  4 , thereby causing the driver spring  6  to force the driver assembly  4  downward. The downward force imparted to the driver assembly  4  by the spring  6  causes the head H of the driver assembly to strike a staple or other fastener located at the forwardmost end of the magazine assembly  15  and in the path of the driver, and drive the staple or fastener into the work surface below. Those skilled in the art will recognize that other ways to actuate the driver, including any stored energy source (such as leaf springs, torsion springs, electricity, hydraulics and compressed gas (e.g. air)) can be used.  
         [0023]     Turning now to  FIGS. 2 and 3 , the details of a drive blade suitable for use with conventional staples are shown. The head H of the driver  4  is configured to correspond in shape to the top (or crown) portion of the staple or fastener (not shown), and the radiused transitional areas (shoulders) which join the crown to the staple legs so that upon impact, the driver  4  squarely engages the staple crown and shoulder portions and forces the staple straight out of the tool and into the substrate. Thus, the center portion of the head H is recessed slightly, with spaced opposite tips  57 ,  58  extending lower than the recessed portion, and being radiused as shown. The length of the blade  4  is predetermined and depends in part on the length of the staple and the characteristics of the substrate into which the staple is being driven, so that the staple does not penetrate into the substrate too deeply. Typical substrates include standard wood building materials used in studs, joists, rafters, etc.  
         [0024]     Nose piece  3  secures over the driver  4 . At its sides, the nose piece  3  extends below the driver as shown in  FIG. 3 . A notch  30 , such as a U-shaped notch, is formed in the bottom of the nose piece  3 . This notch  30  provides a receptacle and guide for the wire or other object to be fastened to be positioned relative to the staple gun. The bottom of the driver  4  at rest is in a specified relationship to the bottom of the nosepiece  30 A. This orientation of the driver  4  and the bottom of the nosepiece insures that the staple tool does not drive the fastener too deeply, thereby possibly crushing, damaging or deforming the object to be fastened. This relationship also inhibits damage to the object if the gun is fired on a cable without fasteners in the magazine. This distance may vary, based on varying the thickness of the crown portion of the fastener.  
         [0025]     The staple gun of the preferred embodiment of the present invention is adapted to drive U-shaped staples (releasably interconnected in the staple magazine) into a substrate in order to connect an object such as wire, cable or tubing to the substrate.  
         [0026]     Those skilled in the art will recognize that any stored energy source can be used to actuate the driver of the fastening tool, including, without limitation, mechanical means, compressed air, electric means, hydraulics, etc.  
         [0027]     In one embodiment of the present invention, the impact pad  13  affects the location of the bottom H of the driver in the “rest” (down) position as it relates to the bottom of the nosepiece  30 A, and thereby controls the extent to which the driver drives the fastener over the object and into the substrate. For example, the modification of the dimensions and/or location of the impact pad can be designed to prevent the driver from driving the staple too tightly over the wire or object being fastened regardless of the diameter of the wire or object.  
         [0028]     Turning now to  FIGS. 4 and 5 , the modified impact pad  13  of this embodiment is illustrated. In the embodiment shown, impact pad  13  is fixed in the housing of the fastening tool with a pair of opposite ledges  14  that extend beyond the main body  30  of the impact pad  13  a sufficient distance to align with respective opposite slots  14 A and  14 B ( FIG. 1 ) in the sides  1 A and  1 B of the tool body  1 .  
         [0029]     As can be best seen in  FIG. 5 , the height or thickness of the main body  300  of the impact pad  13  preferably extends higher than the height of the ledges  14 , and is higher or thicker than that of conventional impact pads. For example, the height of the main body in conventional impact pads is about 0.125 inches. In this embodiment of the present invention, the height of the impact pad main body  300  has been modified to about 0.250 inches.  
         [0030]     By so constructing the impact pad  13 , the fastener of the present invention is designed to fire a fastener about an object to connect it to a substrate without deforming the object. That is, in this embodiment, the height above the substrate at which the driver stops driving the fastener is greater than that conventionally used, so that the fastener does not penetrate as deeply into the substrate. Preferably the fastener penetrates into the substrate enough to attach the object thereto, yet enables the object to remain loose, and therefore be moved, under the fastener. Although slight contact between the fastener and the object being fastened is acceptable and desirable, it is within the scope of the present invention to retain an object in place on a substrate by surrounding the object with the fastener without contacting the object with the fastener, thereby maintaining a gap between the object and the fastener. The length of the drive path of the driver is thus predetermined to be such that upon actuation of the driver and firing of the fastener, a minimum predetermined distance between the substrate and the underside of the top (e.g., crown) of the fastener (e.g., staple) is maintained, such minimum predetermined distance being equal to or greater than the diameter or height of the object being attached to that substrate.  
         [0031]     Similarly, the driver path can be modified so that the fastener more tightly engages the object and penetrates more deeply into the substrate. Those skilled in the art will appreciate the flexibility of the present invention is such that the holding power and movement of the object being held can be modified to virtually any degree desired by modifying the drive path of the driver accordingly.  
         [0032]     Other ways to achieve the objectives of the present invention can be used. For example, the length of the driver itself can be shortened, so as to effectively shorten its path of travel. Alternatively, by modifying the linkage fulcrum pivot points of the tool, the driver path length can be shortened. Alternatively, by lowering the bottom of the nose piece, the distance between the substrate and the underside of the top (e.g., crown) of the fastener (e.g., staple) can be modified.  
         [0033]     In operation, the fastening tool of the preferred embodiment of the present invention can be used as follows. First, cohered cores or individual articles such as fasteners (e.g., staples) are loaded into the magazine. The tool is then aligned over the object to be fastened. Upon actuation of the driver, fasteners are expelled from the magazine, one at a time, around the object to be fastened on three sides and into the substrate. The staple pusher in the magazine assembly automatically urges the next article into axial alignment with the drive path to be expelled by the next complete drive stroke. The path of the driver is effectively shortened, preferably by the driver impacting the impact pad sooner than conventional, so that the staple does not deform the object to be fastened.  
         [0034]     In another embodiment of the present invention, the fasteners  201 , preferably staples, include angled divergent fastener points as shown in  FIGS. 6A, 6B  and  6 C, designed to increase the friction with the substrate when driven into the substrate. This increased friction causes the fastener to stop its penetration into the substrate sooner than otherwise. More specifically, the fastener  201 , such as a wire ribbon, is U-shaped or substantially U-shaped and includes first and second legs or extremities  208 ,  209 . The ribbon has a first edge  211  and a second edge  212 . The first extremity  208  is cut away at an angle or chamfered in the area approaching its free end, such that the first edge  211  forms a point and projects further than the second edge  212 . Similarly, the second extremity  209  is cut away an angle or chamfered in the area approaching its free end, such that the second edge  212  forms a point and projects further than the first edge  211 .  
         [0035]     The more horizontal the angle of the legs, the more the legs diverge, and the more friction that is created. Suitable angles range from about 30° to about 60° from parallel to the surface of the substrate, with each leg of the staple diverging in opposite directions, i.e., away from each other. A preferred angle is about 45°. The angle of the chamfer on each extremity need not be the same, although it is preferred that they are.  
         [0036]     Alternatively or in addition, the fastener legs can be coated with a resin  200  ( FIG. 6C ) that liquefies from the heat from friction generated during application. This allows for easier initial penetration into the substrate. A suitable material is an acrylic/nitrocellulose resin compound, modified with a plasticizer, with the acrylic being the major component, such as UPACO #ST 1685 Withdrawal Coating. Preferably the resin is a combination cement with chemical components that melt at or below the temperature created from the friction caused during fastener application. Preferably the resin is coated to a thickness of from about 0.001 to about 0.0025 inches on the outside face of each fastener leg or extremity, generally half to two-thirds up the leg from the free end of the fastener leg.