Abstract:
A staple gun tacker includes a wire guide mechanism in its forward end which includes a wire guide plate having a recessed lower end for engaging a wire when the plate is in an extended position and a rotatable cam for moving the plate between extended and retracted positions which includes a circular slot formed therein having one end thereof located closer to the axis of rotation of the cam then the other receiving and engaged with a projection on the cam plate so that rotation of the cam is translated into linear movement of the wire guide plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/946,496 filed Nov. 15, 2010, now U.S. Pat. No. 8,240,535, the disclosure of which is incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The multiple embodiments disclosed herein are directed towards the field of staple guns, and more particularly to a wire guide element for positioning the staple driving end of a staple gun tacker with respect to a wire or cable to be stapled to a workpiece. 
     BACKGROUND 
     Staple guns are well known hand-held tools adapted to drive staples into a workpiece. Arrow Fastener Co. manufactures and sells numerous models of such devices, including the manually operated non-powered staple gun sold under the T 50® brand name, and more recently powered models, such as the cordless CT 50™ staple gun. 
     It is known to provide a wire guide for a staple gun, as disclosed for example in U.S. Pat. No. 5,884,829, and U.S. patent application Ser. No. 12/920,395, filed Aug. 31, 2010 both of which are assigned to the Arrow Fastener Co. and incorporated herein by reference. A wire guide is an element having a recessed surface that fits around a wire or cable to be stapled to a wall or workpiece to position the staple gun so that a staple can be driven reliably over the wire or cable to attach it to the workpiece. The wire guide itself typically has surfaces on either side of the recess which receives the wire or cable that are positioned against the surface to be stapled during the staple driving operation. These serve to space the staple driving end from the wire to prevent the staple bight from being driven into the wire. 
     Previously proposed wire guide devices have been somewhat complicated to manufacture and cumbersome to use. For example the guide disclosed in U.S. Patent Publication No. 2007/0039994 uses a rotatable dial having a partially gear toothed peripheral surface that engages a pivotally mounted guide. The dial extends from one side of the staple gun and, when rotated, rotates the guide into or out of the staple gun housing. This requires a somewhat wider front housing than normal and the dial is difficult to operate. In addition, a separate, preferably spring biased retaining structure is required to functionally retain the dial so that the guide is held in its deployed or retracted position. 
     The staple guide of U.S. patent application Ser. No. 12/920,395, discussed above, is somewhat simpler but also requires multiple components, including a separate spring. That device uses a rotatable knob or switch to rotate a generally oval cam which drives the wire guide into or out of the housing. The knob is located on the front of the housing and has a small protrusion for the operator to use to turn the knob. This is difficult to do, particularly in work gloves. 
     SUMMARY 
     In an embodiment, a wire guide mechanism for a staple gun is disclosed which uses a minimal number of parts and is easily operated to extend and retract the wire guide element from the staple gun housing. 
     In at least one embodiment disclosed herein a staple gun tacker wire guide device of the character described is relatively simple in construction and reliable in use. 
     A staple gun tacker wire guide of the character described herein may require minimal modification of the staple gun and is inexpensive to manufacture. 
     In accordance with an embodiment of a staple gun tacker, such as, without limitation, the T-50® brand stapler made by Arrow Fastener Co., a wire guide mechanism may be positioned in the forward or driving end of the staple gun adjacent the staple driver. The mechanism includes a cam rotatably mounted on an axis that is generally perpendicular to the staple driver and a substantially planar wire guide. The wire guide has a free end including a recess adapted to be positioned over a wire or cable, and it is adapted to be moved between extended and retracted positions by the cam when it is rotated. The cam is generally circular and its periphery extends out of openings in the sides of the staple gun housing to permit the operator to conveniently turn it on its axis. 
     The cam has a generally semi circular slot formed therein which has one end radially closer to the axis of rotation of the cam than its other end. The slot receives a protuberance or pin on the wire guide. When the cam is rotated the engagement of the protuberance or pin on the slot causes the wire guide to move linearly in the housing between extended and retracted positions. This structure provides a simple and easily operated wire guide feature in the staple gun. 
     The above and other objects, features and advantages of this invention will be apparent in the following detailed description of the illustrative embodiments thereof, which is to be read in connection with the accompanying drawings, wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a staple gun incorporating a wire guide apparatus; 
         FIGS. 2 and 3  are front views of the staple gun tacker with part of the cover removed to show the wire guide in its retracted and extended positions respectively; 
         FIG. 4  is an elevational view, similar to  FIG. 1 , with the side housing removed and taken along line  4 - 4  of  FIG. 2  with the wire guide in the extended position; and 
         FIG. 5  is a plan view wire guide plate. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     Unless stated otherwise, directions are used herein with reference to the normal orientation of the staple gun. Thus, the operating handle or lever is at the top of the device, and the direction toward the top is “up.” The staple driver is oriented vertically, located toward the “front” of the gun; staples come out of the “bottom” of the staple gun through a discharge opening, and the direction toward the bottom is “down.” 
     Referring now to the drawings in detail, and initially to  FIG. 1 , a staple gun tacker  10  of generally conventional and known construction is illustrated. The staple gun includes a housing  12 , an operating lever or handle  14 , and a finger hole opening  16 . The interior of the housing contains an activating lever system  18  of known construction as illustrated in  FIG. 4  which, when operated by the user depressing the handle  14 , drives the staple driver or plate, sometimes referred to as the “knive,”  20  downwardly to engage a staple in the staple supply track  22  and drive it out of the track through a staple driving opening  26  in the bottom of the housing. Such staple driving arrangements are well known to those skilled in the art, and therefore are not described herein in detail. 
     A seen in the detail view of  FIGS. 2 and 4  a wire guide mechanism  30  is located in housing  12  immediately in front of the driver plate  20 . The wire guide mechanism includes a flat, circular cam plate  32  which is rotatably mounted in any convenient manner in housing  12 , for example on a pin or rivet secured in the housing in any convenient manner. 
     The rotatable mounting of the cam plate  32  is on an axis of rotation  34  that is perpendicular to driver  20  and to a wire guide plate  36 , shown in detail in  FIG. 5 . The peripheral edge  38  of cam plate  32  is knurled and extends beyond the sides  13  of housing  12  through slots or opening  15  formed therein so that the user can conceivably and easily rotate the cam plate  32  on its axis  34 . 
     In the embodiment shown, the cam plate  32  is rotatable between first and second positions, corresponding to respective first (extended) and second (retracted) positions of the wire guide plate  36  so that the free or bottom end of the wire guide  36  is either not extended from the bottom of the staple gun  10 , as shown in  FIG. 2 , or is extended from the bottom of the staple gun  10 , and ready to be used, as shown in  FIG. 3 . This enables convenient use of the staple gun  10  without the wire guide  36 , in a case where it is not needed for stapling a cable or wire. In those instances, the wire guide  36  is set to its retracted position. 
     As seen in  FIG. 5  the lower end of the wire guide plate  36  has support surfaces  45  on either side of the recess  40 . These surfaces  45  are generally flat and engage the workpiece during a stapling operation. This spaces the driving opening from the workpiece while holding the wire in a fixed position. As a result the staple legs are driven adjacent the wire but the bight of the staple is not driven down to the workpiece, thereby avoiding damage to the wire. 
     The distance between the two surfaces  45  on opposite sides of recess  40  is not critical, and may be, for example, in a range of about 6.0 mm to about 8.0 mm. Likewise, the distance from the top of the recess to the surfaces is not limited. This distance may conveniently be in a range of about 5.0 to 7.0 mm. The top of the recess may be any shape, such as arcuate shape as shown. In the illustrated embodiment the top of the cutout is essentially in the shape of a semicircle. 
     The wire guide plate  36  may be planar so that it can be accommodated in a low profile housing. Its upper end  42  has lateral extensions  44  which are adopted to slide in tracks, grooves or the like on the inner surfaces of housing  12  to move linearly between the extended and retracted positions shown in  FIGS. 2 and 3 . 
     In order to move the wire guide plate cam  32  is formed with a generally semicircular slot  46  whose arcuate angular extent is slightly more than 180°. As seen in  FIGS. 2 and 3  the slot  46  has two ends, one of which is radially closer to the axis of rotation of cam  32  than the other. These ends are located so that one is on the vertical axis of symmetry to the plate  36  in its path of travel in the retracted position of  FIG. 2  and the other end is in that position in the extended position. 
     The rotation of the cam  32  is translated into the linear movement of the wire guide plate  36  by means on the wire guide plate  36  for engaging the cam  32  in the slot  46 . This means may be an integral protuberance  52  formed in the plate or a pin mounted in the plate and extending into the slot, or the like. 
     In the illustrated embodiments, the protuberance is circular and the ends of slot  46  are complementary to it. These elements are dimensioned to achieve a friction fit to help hold the plate  36  firmly in its extended and retracted positions. 
     Preferably slot  46  has an arcuate extent of more than 180°, say 180° to 210°, so that a secure stop or locking function is provided to resist movement of the plate in its extended or retracted positions, except upon rotation of the cam  32 . 
     Although at least one illustrative embodiment has been described herein with reference to the accompanying drawings, it is to be understood that various changes and modifications may be effected therein by those skilled in the art without departing from the scope or spirit of this invention. 
     While various embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.