Patent Publication Number: US-6216568-B1

Title: Pliers for removing knockouts

Description:
BACKGROUND OF THF INVENTION 
     The present invention relates generally to a novel set of pliers and to a method for using said pliers to remove knockouts from steel outlet boxes, electrical conduit boxes or junction boxes and the like. 
     In the construction industry, it is widely known to use steel outlet boxes or junction boxes to serve as the point of origin, termination or coupling for electrical wiring, conduit and the like. The junction boxes are usually comprised of four side walls and a back wall. Since the direction of entry to the junction boxes varies, the side walls contain a plurality of removable knockouts. Further, to customize the placement of such metal boxes while also maintaining their integrity, the knockouts are only removed from the sides of the junction boxes which will receive wiring, conduit or the like. Normally the knockouts are coined or cut into the metal side walls of the respective junction box except for a tab, where the tab primarily secures the knockouts to the junction box. 
     The normal practice in the industry for removing knockouts is to place the head of a screwdriver within the circumference of a knockout and to strike the screwdriver with a blunt object, such as a hammer. This normally produces a force in one direction that fractures a portion of the knockout thereby causing the knockout to bend in relation to the supporting side wall of the junction box. The head of the screwdriver can then be used to further pry or bend the knockout in relation to the supporting side wall. With one side of the knockout now accessible, a pair of pliers or other gripping means can be used to secure the knockout and bend and twist the knockout until the remaining portion of the knockout is fractured thereby releasing the knockout. This process is time consuming and has a potential for damaging the junction box. 
     Also, it is sometimes the case that modification of junction boxes that are already installed will be performed. Under the normal practice in the industry, this may be problematic because fracturing the concentric knockout with a hammer and screwdriver requires adequate clearance and installed junction boxes may be located in tightly fitted areas. 
     The pliers that are currently available do not provide an adjustable plier jaw structure capable of quickly and easily removing knockouts. For example, as it is known in the art, pliers typically include two plier arms which are pivotally and adjustably interconnected, where the two plier arms further include opposing jaw portions that abut one another. As is further understood by those skilled in the art, the abutting portions of the pliers jaw allows the pliers to grip objects of varying sizes. This is typically performed by pivoting the plier arms in a manner to cause the two opposed jaw portions to form an open jaw, placing a particular object within the jaws, and then pivoting the plier arms in an opposite manner to cause the two opposed jaw portions to close on the object. The plier arms can also be adjusted to provide a larger or smaller jaw opening. An example of means for adjusting the size of the jaw opening are more clearly disclosed in U.S. Pat. No. 5,134,908. This patent discloses several different embodiments for pivotally and adjustably interconnecting two plier arms. Specifically, the jaws can be selectively adjusted to a variety of preset positions. Further examples of adjustable pliers may also be seen in U.S. Pat. No. 4,890,519, U.S. Pat. No. 4,901,609 and U.S. Pat. No. 5,676,029. 
     While the adjustable pliers shown in the prior art work well for their intended purpose and for removing knockouts once they have been fractured, they are not capable of quickly and easily fracturing the knockouts. In fact, this is why pliers are not currently used in the process of fracturing knockouts. This results from the fact that pliers are designed to provide force at a single point, and in primarily, equal and opposite directions. Thus, such pliers are not capable of providing the torque necessary to shear or fracture the knockout. 
     As a result of these noted deficiencies in the prior art, it is an object of the present invention to provide a set of pliers having an improved means for quickly and easily removing knockouts and improved means for providing opposing and offset forces which produce a greater quantity of sheer force upon a concentric or standard knockout. 
     SUMMARY OF THE INVENTION 
     The subject invention overcomes the deficiencies in the prior art by providing a set of pliers capable of providing two opposing and offset forces upon concentric and disc knockouts with a single tool and a method for removing said knockouts from steel outlet boxes, electrical conduit boxes or junction boxes and the like. This includes the various elements of the invention which act in conjunction with one another to quickly and easily remove knockouts. For example, the pliers include a first arm having a first end and a second end and a second arm having a first end and a second end, where the first arm and the second arm are pivotally connected with respect to each other by an interconnecting mechanism located between the first and second ends thereof. The first arm forms a first jaw located above the interconnecting mechanism of the first arm and the second arm forms an opposing, second jaw located above the interconnecting mechanism of the second arm. The first jaw includes a first projection that extends from an area between the end of the first jaw portion and the interconnecting mechanism. The second jaw of the second arm includes a second projection that extends from the end of the second jaw. The end of the first projection abuts the second jaw and the end of the second projection abuts the first jaw. Thus, the first and second projection are offset from one another so that they do not touch. By strategically placing one of the projections within the circumference of a knockout located on a junction box and the other projection along the outer periphery of said knockout and squeezing the first and second arms, opposing and offset forces are applied to the knockout and junction box frame, respectively, and at least one end of the knockout is easily and quickly fractured. The pliers in accordance with this invention could also include an adjustable interconnecting mechanism and could be used for a wide range of other purposes. Therefore, this invention is not limited to the usages described herein. 
     The foregoing features and advantages of the present invention will be apparent from the following more particular description of the invention. The accompanying drawings, listed hereinbelow, are useful in explaining the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of the pliers of the present invention in an open position; 
     FIG. 2 is a front view of said pliers in a closed position; 
     FIG. 3 is a perspective view of said pliers engaging an outlet box and more particularly a concentric or standard knockout; 
     FIG. 4 is a perspective view of an outlet box with a fractured knockout; 
     FIG. 5 is a perspective view of the prying means interacting with the fractured knockout shown in FIG. 4; 
     FIG. 6 is a perspective view of the pliers securing the knockout; 
     FIG. 7 is front view of the second embodiment of the pliers claimed in the present invention in an open position; 
     FIG. 8 is a front view of prior art pliers showing adjustable interconnecting means similar to those provided in the second embodiment of the inventive pliers disclosed herein. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a front view of the inventive pliers  10 . Briefly, pliers  10  includes a first arm  12  having a first end  42  and a second end  44  and a second arm  14  having a first end  46  and a second end  48 . The first arm  12  and the second arm  14  are pivotally connected to one another by an interconnecting mechanism  16 , which can be adjustable as is known in the art. Arms  12  and  14  may be comprised of steel, aluminum, or any other solid material capable of being shaped into pliers and withstanding a high level of force. First arm  12  forms a first jaw  18  above the interconnecting mechanism  16  and second arm  14  also forms an opposing second jaw  20  above the interconnecting mechanism  16 . First jaw  18  includes a first projection  22  located between first end  42  of first arm  12  and interconnecting mechanism  16  and extending from first jaw  18  toward second jaw  20 . Second jaw  20  includes a second projection  26  that extends from first end  46  of second arm  14  toward first jaw  18 . Projections  22  and  26  are offset from each other and therefore do not touch one another. 
     As shown in FIG. 2, when pliers  10  is in a closed position, projections  22  and  26  abut opposing jaws  20  and  18 , respectively. As will be discussed below, such positioning of first projection  22  and second projection  26  allows pliers  10  to apply a greater quantity of sheer force, at a point between projections  22  and  26 , on a length of material which extends between first projection  22  and second projection  26 . First arm  12  and second arm  14  also include first handle  30  and second handle  32 , respectively. As discussed below, arms  12  and  14  are pivotally connected in a manner that allows the movement of first handle  30  toward second handle  32  to cause an equal movement in first jaw  18  toward second jaw  20 , thereby forming an open and closed position for the pliers  10 , as shown in FIGS. 1 and 2. In addition, first handle  30  can be longer than second handle  32  thereby forming a prying means  34 . 
     Refer now to FIG. 3, which shows pliers  10  engaging a steel outlet box or junction box. First projection  26  can be placed within the circumference of a concentric knockout or a standard knockout  36 , while second projection  22  can be placed on a side wall  38  of the box  40 . By closing the jaw of pliers  10 , i.e., moving the first handle  30  toward the second handle  32 , first projection  22  and second projection  26  apply force to the side wall  38  and the knockout  36  in opposite and offset directions (indicated by the arrow tipped lines adjacent the projections and normal to the side wall). This applies sheer force in two opposed directions with regard to knockout  36  thereby causing said knockout  36  to be fractured from the side wall  38 . 
     Refer now to FIGS. 4-6 which show the pliers  10  interacting with the fractured knockout  36 . As shown in FIG. 5, the prying means  34  of the first handle  30  is positioned between the opening (created by fracturing the knockout) between the knockout  36  and side wall  38 . Because prying means  34  can be located at the end of first handle  30  by forming first handle  30  to be longer than second handle  32 . This increased length provides the prying means  34  with greater leverage. As shown in FIG. 5, by prying knockout  36 , the opening between knockout  36  and side wall  38  is expanded. As shown further in FIG. 6, pliers  10  are capable of grabbing knockout  36  to complete removal of said knockout  36 , similar in function to the prior art pliers. Specifically, knockout  36  is positioned between the second projection  26  and the end  19  of the first jaw  18 , and then first handle  30  is moved toward second handle  32  thereby securing knockout  36 . After pliers  10  have secured knockout  36 , pliers  10  can be used to twist and turn the knockout until any portion of the knockout  36  which is still attached becomes fractured. 
     Refer now to FIG. 7 which shows a second embodiment of pliers  10 . Specifically, pliers  10  comprise an adjustable interconnecting mechanism  16 . The interconnecting mechanism  16  allows arms  12  and  14  to be adjusted in relation to one another which in turn allows the distance between first projection  22  and second projection  26  to be varied. The manner for providing adjustable pliers is well known in the art. For example, FIG. 8 shows prior art pliers which disclose an adjustable pair of pliers utilizing a tongue and groove arrangement like the adjustable interconnecting mechanism provided in the second embodiment of the subject application shown in FIG.  7 . 
     While the invention has been particularly shown and described with reference to a particular embodiment thereof it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.