Patent Publication Number: US-2010116109-A1

Title: Adapter to convert electrical box punch dies into self centering punch dies

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 11/552,236, filed on Oct. 24, 2006, entitled ADAPTER TO CONVERT ELECTRICAL BOX PUNCH DIES INTO SELF CENTERING PUNCH DIES, by Brian Ray which application is now pending and the disclosure of which is incorporated herein by reference and which application claims priority to U.S. Provisional Patent Application Ser. No. 60/730,674 filed Oct. 26, 2005, entitled ADAPTER TO CONVERT ELECTRICAL BOX PUNCH DIES INTO SELF CENTERING PUNCH DIES, by Brian Ray and the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention generally relates to enlarging a hole in a substrate such that the enlarged hole is centered on the existing hole. Specifically, this invention refers to knock-out dies for enlarging the holes formed by knock-outs or slugs in an electrical box, and to an apparatus and method for centering the enlarged holes relative to the existing knock-out holes. 
     2. State of the Art 
     For many years, Knock-out dies with centering capability are provided by a centering element integral with the blade or punch of the die. These dies may be used to replace non-centering dies for users that wish to upgrade from their non-centering dies. 
     DISCLOSURE OF THE INVENTION 
     In a simple form, the invention may include a knock-out punch and die tool for enlarging a knock-out hole in an electrical box. The punch and die tool may include a punch, a generally cup configured die, and a threaded central shaft supporting the punch on a first end of the shaft and a die on an opposite second end of the shaft. Advantageously, the punch and die tool may further include a repeatably removable centering element received in a cup portion of the die. Furthermore, the punch and die tool may include a resilient element urging the centering element in an axial direction along a length of the shaft outwardly of the cup portion. It is to be understood that the centering element may have a beveled structure that extends radially inwardly toward the shaft in a direction outwardly of the cup portion. The centering element may also have a central through opening surrounding the shaft, and a counter bore of larger diameter than the through opening extending at least a portion of the length of the through opening. The counter bore may thus receive and removably hold a portion of the resilient member. The counter bore may be located within the beveled structure. In another configuration, the counter bore may have a tapered portion and the resilient element may be a spring with a generally tapered shape. In such a configuration, the spring may fit within the centering element when the spring is in the folded or contracted position. 
     In another simple form, the present invention may include an assembly for a punch and die set. The assembly may include a centering element having a toroid configuration with a central axis perpendicular to a plane of the toroid configuration. The assembly may also include a resilient member removably connected to the centering element. The resilient member may be generally centered relative to the central axis after assembly and during use. 
     It is to be understood that while only a beveled surface generally tapering toward a point is needed for the centering element, in a particular configuration the toroid configuration may be generally or specifically a quoit configuration. 
     The assembly may be packaged or otherwise sold as separate pieces or as a kit. In fact, the invention includes a kit having assemblies for a variety of sizes of punches and dies. It is to be understood that the assemblies or kits may be utilized in punch and die tools, even when the punch and die tools do not form part of the kit or assembly. 
     The present invention may include a method of enlarging a hole in a substrate. In a simple form, the method may include forming a hole centered on an existing hole in the substrate. Forming the hole may be achieved by repeatably removably placing a centering element in a die of a punch and die tool. The method of enlarging the hole may further include placing a resilient element in the die of the punch and die tool. In a particular example, the substrate includes a wall or other surface of an electrical box and the existing hole includes a knock-out hole in the surface of the electrical box. 
     It is to be understood that the step of removably placing the centering piece may include surrounding a central threaded shaft of the punch and die tool, and the step of placing the resilient member may also include surrounding a central threaded shaft of the punch and die tool. The method may include placing the resilient element between the centering element and a base or bottom of a cup formed in the die. 
     The method may further include urging the centering element into centering engagement with the existing hole. The centering engagement may be effected by the resilient member and/or by moving the punch and die toward each other. The reaction to the centering engagement may include automatically urging the punch and die into a central position relative to the existing hole in the substrate. 
     The method may include placing the punch and die tool on the substrate with the shaft extending through the existing hole. The method may specifically include placing the punch on a first side of the substrate and placing the centering element and the die on the other side of the substrate, so that the shaft extends through the existing hole. The method may also include moving the punch toward the die, and thus cutting material of the substrate with a blade of the punch in a centered relation to the existing hole. As may be appreciated, the method may include automatically removing the material cut by the blade by urging the material out of the die. The material may be pushed out of the die by the centering element and resilient element. 
     In another simple form, the present invention may include a method of converting a non-centering punch and die into a centering punch and die tool. This method may include repeatably removably retrofitting an assembly comprising a toroidal centering element and a resilient element in a cup portion of a die. This method may also include one or more of the method steps described above. 
     The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a punch and die tool and the centering assembly according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of a centering assembly according to an embodiment of the present invention; 
         FIG. 3  is a perspective view of a prior art punch and die tool with which the assembly of the present invention may be used according to the present invention; 
         FIGS. 4A and 4B  are respective cross-sectional views of the assembly with inner walls that are essentially vertical and inner walls that are partially tapered; and 
         FIG. 5  is a perspective view showing a centering effect in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     As discussed above, embodiments of the present invention relate to an adapter to convert electrical box punch dies into self centering punch dies. Presently, the invention comprises: a spring loaded centering element or beveled piece  10  that fits in and is biased upwardly out of a die or cup portion  15  of a punch die  21 , as shown in  FIGS. 1 ,  2 , and  3 , by a resilient element or spring  22 . In use, the beveled piece  10  engages a knock out or slug opening in a substrate to cause the centering, while the blade  25  of a punch  27  engages the substrate from an opposite side of the substrate relative to the beveled piece  10 . The adapter including the beveled piece  10  and the spring  22  can convert a non-centering punch die  20  (shown in  FIG. 3 ) into a centering punch die  21 , as shown in  FIG. 1 . The adapter is repeatably removable so that the centering punch die  21  can be converted back into a non-centering punch die  20  upon removal of the adapter. 
     Other punch and die manufactures have recently come out with a centering blade that has an integral beveled piece that engages an electrical box wall on a same side as the blade. In this centering device, a beveled element that performs the centering is integral with the blade piece. This requires the consumer to buy a new blade or a whole new punch die if they want the centering feature. On the other hand, with the spring loaded beveled piece of the present invention, conventional non-centering punch dies  20 , (See  FIG. 3 ), can be modified to center the punch on an existing slug hole. That is, consumers will not need to buy a new blade or new die. Rather they can buy the adapter of the present invention and retrofit it to their old punch dies. The adapter is repeatably removable so that the non-centering punch die  20  can be converted to a centering punch die  21  using the adapter and can later be used as a non-centering punch die  20  by removing the adapter. 
       FIG. 4A  shows additional details including a through opening  30  and a counter bore  33  that releaseably holds the spring  22 . The counter bore  33  has a larger diameter than the through opening  30 . The through opening  30  arid the counter bore  33  may be located within the beveled surface of the toroidal centering element  10 . Other configurations are possible without departing from the spirit and scope of the invention. For example, spring  22  may be replaced by a resilient element that is formed at least in part by an elastomeric material. The beveled surface of the centering element may not be a uniform taper, but may have a rounded or other contoured configuration. The assembly of the centering element  10  and the resilient element  22  may be integral or one piece, and may be pre-assembled or integrally molded, for example. 
       FIG. 4B  shows another configuration of the assembly where the centering element  110  may include a tapered portion  120  of the inner sidewall. The counter bore in this configuration may include a vertical portion  133  as well as the tapered portion  120 . The through opening  130  and the counter bore including the vertical portion  133  and the tapered portion  120  may be located within the beveled surface of the centering element  110 . In this configuration, the spring  122  may have a generally tapered shape so that the spring  122  may fit within the centering element  110  when the spring  122  is in a folded or contracted position. Alternatively, the counter bore may include only a tapered sidewall. 
     With regard to  FIG. 5 , a die tool and centering assembly in accordance with the present invention is shown applied to a knock-out hole  34  in a substrate  35  that may form a wall of an electrical box. In accordance with a method of the present invention, as the shaft  36  is turned in a tightening direction, the die  15  is drawn toward the substrate and the punch, which is on the opposite side of the substrate (not shown in this Figure). The centering element  10  will also be urged into engagement with the substrate  35  and in particular will be engaged in the structure forming the knock-out hole  34 . As the centering element engages at a point  39  and is further tightened, for example, the punch and die tool will be urged in a centering direction of arrow  42 . Thus, when the punch engages an opposite surface of the substrate  35 , it will be centered relative to the hole  34 . 
     The toroidal centering element  10  of the present invention has a maximum diameter smaller than the inner diameter of the cup portion of die  15 . The present invention also includes a combination of an electrical box die and a spring loaded beveled piece that has a maximum diameter smaller than an inner diameter of a die cup portion of the die with the beveled piece. This size relationship enables easy placement and removal of the beveled piece  10  and spring  22  in the die. That is, the assembly of the beveled piece  10  and spring  22  may be used as a retrofit assembly or kit. The assembly may be added to or removed from the die as often as desired by the user. Without the assembly, the die is in a non-centering configuration and adding the assembly converts the die to a centering configuration. 
     The present invention also includes the methods described above including forming holes centered on knock out holes in electrical boxes and which may include steps that are required for inserting the beveled piece and spring into an electrical box die cup. 
     The embodiments and examples set forth herein were presented in order to best explain the present invention and its practical application and to thereby enable those of ordinary skill in the art to make and use the invention. However, those of ordinary skill in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the teachings above without departing from the spirit and scope of the present invention.