Patent Publication Number: US-7707761-B2

Title: Process for manufacturing double barrel shotgun barrels, and the resulting double barrels

Description:
PRIOR APPLICATION 
   The present invention claims priority from, and is a continuation application of, U.S. patent application Ser. No. 11/344,493 filed Feb. 1, 2006, which is incorporated herein by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to a process for metal working to produce double barrel shotgun barrels, and, more particularly it relates to a process for manufacturing over/under and side-by-side shotgun barrels from a single piece metal stock, and also to the resulting monolithic shotgun barrels so produced. 
   2. Description of the Prior Art 
   Double barrel shotguns are long known in the art. There are two basic types of double barrel shotguns being manufactured today. A first type of double barrel shotgun is commonly referred to as a “Chopper Lump” (English terminology) or a “Demibloc (Italian terminology)” barrel, and will herein be referred to as “Demibloc”. Demibloc barrels are formed from two metal tubes or single barrels, preferably of steel, that are of a length sufficient to form a shotgun. As a first significant step, the two metal tubes soldered together to form a roughly joined double barrel. The resulting double barrel is then filed, machined and otherwise worked in multiple steps using the skills and labor of multiple trades and crafts people. For example, as a first step a “Joiner” joins the two individual metal tubes and then solders them together along substantially their entire lengths. An “Actioner” fits and files the rough barrel to fit and match a separate action or firing mechanism to which the double barrel is to be attached. A “Striker” files the surfaces of the joined rough double barrel pieces to a desired finish. A “Straightener” straightens or regulates the joined barrels and also adjusts or bends the individual barrels by eye into a relative position to allow each barrel to shoot a projectile straight and also into a desired converging shot pattern at a given distance. A “Rib installer” solders the top sighting rib onto the combined double barrel tube, and also solders side ribs on either side of the tubes between the two barrels to secure them in the desired relative position. Finally, a “Bluer” treats the combined double barrel to produce the desired oxidized blue-black coating onto the double barrel. 
   The second type of double barrel shotgun is commonly referred to as a “Monobloc” (Italian term). A Monobloc double barrel shotgun consists of an action block of metal, preferably steel, fitted to the action or firing mechanism of the shotgun. The Monobloc is preformed to carry at least two receiving holes designed to accept a pair of separate barrel tubes. Each separate tube is then set into and soldered to a receiving hole of the action block so that each protrudes from the action block, and is of a length sufficient to be formed into a shotgun. The two tubes are then held in position with wire or by a fixture and are then roughly tacked together along their entire lengths with solder. Then, the joined barrels are straightened or “Regulated” by hand into a relative position to allow each barrel to shoot a projectile straight and also into a desired converging or overlapping shot pattern at a prescribed distance. Next, the barrels are sent to a “Rib installer” to solder the top sighting rib and side ribs between the barrels that hold the tubes in place. The rough barrels are then sent to a “Striker” or “Finisher” to finish the surfaces of the barrels by filing and sanding. Finally, the barrels are sent to “Bluer” for bluing and final finish. 
   In addition, double barrel shotgun barrels are formed by the Demibloc and by the Monobloc process in over/under (O/U) and side by side (S/S) shotgun barrels 
   It can therefore be seen, that the process of making a double barrel, whether by the Demibloc or the Monobloc process consists of a large number steps performed by many crafts an trades people, and, as a practical matter requires a great deal of time, say up to two and one half years to complete. 
   Accordingly, there exists a need for a process for manufacturing double barrel shotgun barrel systems which allows what have heretofore been many dissimilar trades to perform manufacturing and machining and finishing steps quickly, efficiently and in harmony in order to arrive at a finished double barrel shotgun barrel within a required specification. Additionally, a need exists for a process for manufacturing shotgun barrels which is quick and inexpensive and easy to replicate with precision. Furthermore, there exists a need for a process for manufacturing double barrel over/under and/or side by side shotgun barrels which allow a broad range of different types of barrels to be produced using substantially the same single piece of metal stock and material blank. There is a further need to precisely produce such double barrel over/under and/or side by side shotgun barrels quickly and without the use of the labor of multiple trades or craftsmen. 
   SUMMARY OF THE INVENTION 
   The present invention teaches methods for manufacturing double barrel shotgun barrels. In one embodiment the method comprises providing an elongated metal stock material of a given length and of sufficient height and width to be formed into a double barrel shotgun, the metal stock material having a first end and a second end. So long as the metal stock material meets those size requirements, it may be round, or square, or rectilinear or irregular in cross section, the desired starting cross section being easily milled or otherwise formed on the metal stock material. For purposes of simplicity it will be assumed that the metal stock material is round, or cylindrical or rectilinear in cross-section. As a first significant step in creating the double barrel of the present invention, two separate and spaced apart index markers are formed at both the first end of the metal stock material and at the second end of the metal stock material. The second index marker formed in the second end of the metal stock material is opposed to and aligned precisely linearly with the first index marker formed in the first end of the metal stock material longitudinally through the length of the metal stock material. The second index marker formed in the second end of the metal stock material is also opposed to and aligned linearly with the first index marker formed in the first end of the metal stock material longitudinally through the length of the metal stock material. Each pair of opposed first and second index markers serve to define what will be the centers of to-be-bored holes. In addition, and as is explained below, the index markers allow the metal stock material to be moved from one machine to another during various steps of the process of the present invention. 
   A first substantially straight guide element is then formed linearly along one surface of the external longitudinal length of the metal stock material. The first guide marker runs in a substantially straight line between the first end of the metal stock material and the second end of the metal stock material. A second guide marker is then formed linearly along the external longitudinal length of the metal stock material, and runs in a substantially straight line between the first end of the metal stock material and the second end of the metal stock material. However, the second external guide marker is spaced apart from and on a surface opposed to the first guide marker, and as explained and greater detailed below, is angled relative to the first external guide marker at what will be the angle of convergence of the to-be-formed bore holes. Then, using the first and second pairs of index markers, the first and second holes to be bored are established A first bore hole is formed linearly through the length of the metal stock material, the first bore hole being aligned with and guided by the first guide marker. Then, the second pair of index markers are used to establish the location of the second bore hole to be formed linearly through the length of the metal stock material, the second bore hole being aligned with and guided by the angle of the second guide marker, and therefore at the predetermined angle of convergence at a given distance from the end of the barrels. In practice, the angle of convergence between the first projectile hole and the second projectile hole is usually in the range of about 0.35° and about 0.4°. All of these steps are achieved with a minimum of handling; require no skilled trades or craftsmen. Then, the double barrel thus formed may be profiled and finished with a minimum of handling and without requiring skilled trades or crafts people. 
   As used with the present invention, the “index markers” may be holes or raised points, or any other form of index marker. Similarly, the “guide element” may be grooves, rails, or any other form of guide element. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view illustrating a state-of-the-art stock and trigger mechanism in relation to a finished over/under double barrel shotgun barrel constructed in accordance with the process of the present invention; 
       FIG. 2  is a perspective view illustrating a state-of-the-art stock and trigger mechanism shown joined to a finished side-by-side double barrel shotgun barrel constructed in accordance with the process of the present invention; 
       FIG. 3  is an interrupted side elevational view illustrating a typical solid cylindrical metal stock material before it has undergone any of the steps of the method of the present invention to produce a double barrel shotgun barrel; 
       FIG. 4  is a right end elevational view of the cylindrical metal stock material of  FIG. 3  before it has undergone any of the steps of the method of the present invention, the left end view being a mirror image thereof; 
       FIG. 5  is an elevational side view of the cylindrical metal stock material of  FIG. 3 , partially in section at its left and right ends to illustrate a pair of index holes at its left and right ends; 
       FIG. 6  is a right end elevational view of the cylindrical metal stock material of  FIG. 5  illustrating the pair of index holes, the left end view being a mirror image thereof; 
       FIG. 7  is an elevational sectional side view of the metal stock material of  FIG. 5 , and now further processed and illustrating first and second converging guide grooves formed in the outer surface of the stock material; 
       FIG. 8  is a right end elevational view of the cylindrical metal stock material of  FIG. 7  illustrating the first and second converging guide grooves as well as the pair of index holes, the right end view being substantially a mirror image thereof, but with the guide grooves slightly closer to one another; 
       FIG. 9  is an elevational sectional side view of the metal stock material of  FIG. 7 , but now further processed and illustrating first and second bore holes formed through the stock material, with fixture holes shown formed at the left end of both the first and second bore holes, but at only the first bore hole on the right end, and further illustrating holes drilled into the material for circulation of coolant; 
       FIG. 10  is a left side view of the cylindrical metal stock material of  FIG. 9 , the left end view being similar thereto, but for the absence of a fixture hole in the second bore hole on the right end; 
       FIG. 11  is an elevational side view of the material of  FIG. 9 , but now further processed and illustrating, but for the left and right blocks of stock material, the now nearly complete profiled over/under double barrel shotgun barrel constructed in accordance with the process of the present invention; and 
       FIG. 12  is an elevational side view of the material of  FIG. 11 , but now further processed and illustrating, the left and right blocks of stock material removed, to form a now complete over/under double barrel shotgun barrel, as shown in perspective in  FIG. 1 , and constructed in accordance with the process of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring first to  FIG. 1 , illustrates a perspective view illustrating a complete double barrel shotgun  10 A having a side by side (S/S) double barrel  12 A constructed in accordance with the process of the present invention.  FIG. 2  provides an exploded perspective view illustrating an over/under (O/U) double barrel shotgun  10  including a state-of-the-art butt stock  14  having a trigger mechanism  16  and a forend  18 , in relation to an O/U double barrel  12  constructed in accordance with the process of the present invention, as detailed below. Illustrated on the O/U double barrel  12  are a standard joining or side rib  22  between the two barrels, a top rib  24 , a false rib  26  and a forend latch  28  carried by and produced as parts of a finished over/under double barrel shotgun barrel  12  constructed in accordance with the process of the present invention. Like parts on O/U shotgun  10  and shotgun S/S  10 A have like numbers. 
   The process for manufacturing over/under (O/U)  12  or side by side (S/S)  12 A shotgun barrels of the present invention begins with obtaining a single piece of metal stock material  32 , as shown in  FIGS. 3 and 4 . In the preferred practice of the present invention, the metal stock material  32  is a solid piece of metal, preferably of art known gun barrel grade steel. In the embodiment shown in  FIGS. 3 and 4 , stock material  32  is substantially circular in cross-section, although square or rectangular or other shaped stock material  32  may be used in the method of the present invention. In addition, it is within the scope and teaching of the method of the present invention to produce shotgun barrels  12  or  12 A from other metal stock materials having other workable cross-sections. In any event, the starting metal stock material  32  is generally solid and elongated and has a first end  34  and a second end  36 . For ease of operation and handling, both first end  34  and second end  36  of the solid metal stock material  32  are formed or cut flat and substantially orthogonal to the linear length of the stock material  32 , and both first end  34  and second end  36  are formed substantially parallel to one another. Stock material  32  is of a length, height and width sufficient to be formed into and produce a double barrel O/U  12  or S/S  12 A shotgun barrel. 
   The process of the present invention for manufacturing double barrel O/U or S/S shotgun barrels  12  or  12 A according to the present invention is comprised of several steps, as well as optional steps. The first step, after obtaining an appropriate metal stock material  32 , is determining the ultimate angle of convergence of the first and second two to-be-bored projectile holes  42  and  44 , respectively (see  FIGS. 9 and 10 ). As discussed below, the angle of convergence of projectile holes  42  and  44  is determined by the laws of ballistics and physics. The production of the angle of convergence for projectile holes  42  and  44  begins with forming pairs of index markers  46  and  48  on the first and second ends  34  and  36  of metal stock material  32 . 
   Now, in order to produce and replicate O/U or S/S double barrel barrels accurately and consistently, two precisely located and spaced apart index markers  46  and  48  are formed at the first end  34  of the solid metal stock material  32 , and two precisely located and spaced apart matching index markers  46  and  48  are also formed at the second end  36  of the solid metal stock material  32 . In preferred embodiments each pair of two index markers are a pair of spaced apart holes  46  and  48 , formed, for example, by drilling into the first end  36  and a second end  46  and  48  of solid substantially cylindrical metal stock material  32 . The first pair of index holes  46  and  48  formed in the first end  34  of the metal stock material  32  are preferably aligned linearly with the second pair of index holes  46  and  48  formed in the second end  36  of the metal stock material  32 . Each pair of index holes  46  and  48  are aligned longitudinally through the length of the metal stock material  32  with the opposed pair of index holes  46  and  48 . In the preferred practice of the present invention, the two index markers  46  and  48  at the first end  34  and the two index markers  46  and  48  at the second end  36  of solid stock material  32  are located between about 2.0 inches apart and about 2.5 inches apart. While the index markers  46  and  48  are herein noted to be holes, and specifically to be drilled holes, the index markers may be formed in any other manner, for example as projections, and by any other method. 
   Next, based on the locations of index markers  46  and  48 , the exterior of metal stock material  32  is then profiled, using equipment and methods as detailed below, including the formation of accurately positioned converging external guides  52  and  54 . Converging external guides  52  and  54  are located relative to one another at what will be the angle of convergence of the first and second to-be-bored projectile holes  42  and  44 . As shown in  FIGS. 7 and 8 , such external guides are preferably in the form of straight linear grooves  52  and  54  for use in guiding the boring of the converging bore holes  42  and  44 . A pair of first straight guide grooves  52  are formed linearly, but opposed to one another along both sides of the external longitudinal length of the metal stock material  32 . The first guide groove elements  52  run in a substantially straight line between the first end  34  and second end  36  of metal stock material  42 . A second pair of guide groove elements  54  are then formed linearly, but also opposed to one another along both sides of the external longitudinal length of the metal stock material  32 . along the external longitudinal length of the metal stock material, and also runs in a substantially straight line between the first end  34  of the metal stock material  32  and the second end  36  of the metal stock material  32 . However, the second pair of external guide grooves elements  54  is spaced apart from, and are angled relative to the first pair of external guide groove elements  52 . The angle of the second pair of external guide grooves  54  will serve to guide the angle of convergence of the to-be-formed bore holes  42  and  44 . 
   Then, as illustrated in  FIGS. 9 and 10 , two small, say ¼ inch circulation holes  72  are drilled and tapped, say about 2.5 inches to about 3 inches from the ends  34  and  36  of the metal stock material  32 , and into the first and second projectile bores  42  and  44 . The circulation holes  72  allow for circulation of coolant by art known means during the profiling and Electrical Discharge Machining (EDM) process as described below. The foregoing not withstanding, circulation holes  72  and the step of circulating coolant can be omitted, if desired. 
   Then, after the location and setup of index markers  46  and  48  at ends  34  and  36  of solid metal stock material  32  is used to produce external guide groove elements  52  and  54  for either O/U  12  or S/S  12 A shotgun barrels, external guide groove elements  52  having precise locations and angles of convergence are used to locate two to-be-bored projectile bore holes  42  and  44  that provide the desired overlap pattern that at a given distance. This is accomplished using the first pair of external guide groove elements  52  for alignment, a first bore hole  42  is formed linearly through the longitudinal length of the metal stock material  32 , first bore hole  42  is formed using any suitable boring system. Then, metal stock material  32  is moved and placed into a second alignment with the boring system using second alignment guide groove elements  54 , and second bore hole  44  is then formed linearly through the longitudinal length of the metal stock material  32  also using any suitable boring system, but at the predetermine angle of convergence with first bore hole  42 , as shown in  FIGS. 9 and 10 . It is within the teaching and tolerances of the present invention to produce second bore hole  44  before first bore hole  42 . Thus, the two to-be-bored converging holes  42  and  44  are precisely located and bored based on the positions of the four index holes  46  and  48  holes and the external guide groves  52  and  54 . In the alternative, but not as simply, index holes  46  and  48  can be used, without forming external guide groove elements  52  and  54  to align a moveable machining table or other device to establish an offset angle between bore holes  42  and  54 , for example with Computer Assisted Drawings (CAD) converted to tool paths equipment, or print specification. 
   The method of actually forming bore holes  42  and  44  in stock material  32  is not critical to the practice of the present invention. However, what ever type of bore hole forming system is used, converging external guides  52  and  54  will preferably be used to select and guide the angle of convergence between bore holes  42  and  44 . For example, since the early eighteenth century a fixed, non-moveable single axis hand turned boring or drilling machine has been used to produce bore holes, and may be used to produce bore holes  42  and  44  in the practice of the present invention. This can be accomplished by cutting two longitudinal grooves like  52  and  54  in the surface of stock material  32 , which grooves represent the desired convergent directions of bore holes  42  and  44 . However, in the preferred process of the present invention, state-of-the-art automated power boring machines such as Computer Numerical Controlled (CNC) machines are used with converging external guides  52  and  54  to select and guide the angle of convergence between bore holes  42  and  44 . As an important step in the process of the present invention, in order to accurately replicate bore holes from stock material  32  to stock material  32 , one must mechanically establish the location of those bore hole centers. In the preferred practice of the present invention, those bore hole centers are locatable from index marker elements  46  and  48  which allow each piece of stock material  32  to be moved and repositioned on any boring machine, as the marker elements  46  and  48  serve as reference indexes that identify the correct location of the to-be-bored projectile holes  42  and  44  within the stock material  32 , regardless of what type of boring machine was originally used. Once such converging external guides  52  and  54  are alternately placed on a machining table having a compatible locating element for aligning the boring element, and fixed into position, the boring machine hole line will be represented by the line of the guides  52  and  54 . Therefore, in practice, when a first hole, say  42  is completed using external guides  52 , the stock material  32  can then be placed in the second external guides  54 , and the boring machine aligned to external guides  54 , and bore hole  44  established with the desired angle of convergence. In each instance, the alignment of stock material  32  is established on the table and in the fixture by reference to index markers  46  and  48 . 
   In the alternative, where the boring machine has very accurate moveable tables for positioning stock material  32 , and where the centers of projectile holes  42  and  44  are locatable from index marker elements  46  and  48 , the stock material  32  can be moved and positioned with respect to the boring tools so that and projectile bore holes  42  and  44  can be produced without reference to or use of converging external guides  52  and  54 . Subsequently, the surface of stock material  32 , as shown in  FIGS. 9 and 10 , is then profiled and machine finished to the profile shown in  FIG. 11 , but without removing unfinished end portions  62  and  64 . Such profiling and finishing is easily completed using state-of-the-art CAD and other state-of-the-art machining tools, such as CNC machines and EDM processing. If desired or required, during the profiling and EDM machining processes, circulation holes  72  may be used to circulate coolant within bored projectile holes  42  and  44 . 
   Finally, as shown in  FIG. 12 , end portions  62  and  64  are removed, for example by cutting them off to a specified length, and barrel  12  is completed to produce a now substantially complete O/U double barrel shotgun barrel  12  constructed in accordance with the process of the present invention. Of course, further finishing or customizing of the surfaces, and bluing or other final custom finish may be provided by time consuming art known means. It will be seen that barrel  12  as shown in  FIG. 12  is the same as that shown in  FIG. 12 . In the practice of the method of the present invention the bored stock material is preferably transferred to a state-of-the-art lathe, not shown, for profiling. The holding fixture, also not shown, of the lathe is keyed to the two pairs of index holes  46  and  48  with matching pegs. The index holes  46  and  48  allow the true center of each of the to-be-formed converging bore holes  42  and  44  inside of the metal stock material  32  to be defined. Measurements from the center of bore holes  42  and  44  allows proper finish machining and profiling of the finished product, as shown in  FIGS. 11 and 12 . Such finishing of the bored gun barrel  12  or  12 A is produced by extensive milling, preferably followed by electric discharge machining (EDM). In the EDM finishing step a mating pair of female electrode replicas, not shown, of the profile of the final external barrel are first made. The rough finished barrel is then compressed between the two electrodes and EDM machined until a highly finished external profile is attained. The end result is a barrel  12  or  12 A that, in production, has required little to no hands on specialty human labor. 
   It is apparent, that by adjusting the orientation of the system by 90° in several of the steps discussed above, that a S/S double barrel shotgun barrel  12 A can be produced. It should be noted that side and top ribs  22  and  24  are produced with and integral to the finished double barrel products. 
   In any event, it is clear that in the practice of the method of the present invention, the monolithic O/U or S/S double barrels are not made from a composite of two tubes or single barrels that are joined together, for example by soldering, to make a joined, but not monolithic double barrel. Nor is it necessary for single barrels to be joined together and then bent relative to one another during their joining by eye reckoning into position to a desired angle of convergence, as in the prior art Demibloc and Monobloc processes. Rather, since the starting stock material  32  for production of O/U or S/S double barrels is solid elongated metal stock material in which the two bore holes  42  and  44  are accurately formed having the desired angle of convergence within the solid metal stock material  32 , and remains as a continuously joined monolith that is neither amenable to or capable of having its bore holes  42  and  44  bent relative to one another to adjust their angle of convergence. In addition, the bore holes  42  and  44  formed within the solid metal stock material  32  produced using the method of the present invention react differently to the harmonics waves of flexation that are generated during firing of a projectile through bore holes  42  and  44 , as compared to the flexation produced by the counterpart state-of-the-art joined double barrel produced by conventional Demibloc and Monobloc methods of manufacture, and therefore the angles of convergence that have been determined for use with the prior art joined systems are not applicable to the angles of convergence required for the double barrel shotgun barrels produced by the method of the present invention. It is therefore understood that the determination of the angle of convergence of the two bore holes  42  and  44  produced by the method of the present invention is a key element to producing even and overlaying shot patterns at any given distance. Because of the above noted differences in the harmonics waves of flexation that are generated during firing of projectiles from shotgun barrels produced by the method of the present invention, the selection of the angle of convergence for an O/U or S/S barrel formed from solid metal stock material is also different from those known and used for double barrels produced by prior art Chopper Lump and Demibloc. 
   By using the indexing holes and other steps and techniques described herein, the shotgun barrels produced by the method of the present invention can be reproduced with precision for each to-be-produced shotgun barrel, thus making the shotgun barrels interchangeable from shotgun to shotgun. For the most part, double barrel shotgun barrels produced by prior art methods have required semi-precise machining for each individual shotgun system and further finished by hand, and are not interchangeable from shotgun to shotgun. Similarly, the center to center bored holes  42  and  44  can be produced in sizes that are compatible with a large number of double barrel shotgun barrels in use today of a like gauge. It will be appreciated that the double barrel gun barrels can be finished to assume different forms in accordance to the needs of a manufacturer or gunmaker. A particular profile of a gunmaker&#39;s barrel can be produced in either the O/U or S/S type barrels of the present invention. 
   Thus, the process of the present invention which produces a solid monolithic barrel with little or no hands on skilled labor replaces the Demibloc barrel manufacturing procedures that require multiple trades and a great deal of time to complete. By comparison, the process of making a solid block barrel according to the method of the present invention to produce a single complete one piece solid unit is simple and fast. For example, in the current practice, a Demibloc barrel which is made using a number of Tradesmen takes approximately two and one half years to complete. By comparison, the double barrel of the present invention can be reproducibly manufactured and completely finished in about eight to about 24 hours, depending on the sophistication of the machines used. However, in producing the completed form shown at  FIGS. 1 ,  2  and  12 , the process of the present invention eliminates substantially all of the trade crafts required in the process of making a Demibloc barrel. Further, by selection of premium steel, such as Vacuum Arc Remelt Steel, rarely used because of its difficult machining properties, it can reduce the explosive bursting defects of barrels made of lesser material, thereby potentially saving injuries, life and property. Further, the solid barrel process of the present invention eliminates the issue of solder joints coming loose with use or age. Since side and top ribs  22  and  24  are integral to the finished product, it also prevents them from delaminating, and the soldered joints from separating, as in a Demibloc system, which are common prior art problems. The monolithic barrel produced by the process of the present invention eliminates all of these failures, while at the same time improving barrel burst safety by as much as 700% depending on the metal material selected. Stated simply, seven stages and crafts of prior art Demibloc barrel manufacturing are eliminated by using the solid barrel process of the present invention, while the cost to make the barrel remains about the same or less, and is much quicker and totally reproducible. Furthermore, the double barrel shotgun barrels so produced have close and reproducible tolerances, can be made from one solid piece of steel and can be made to resemble a Monobloc piece design, and can be made as a solid barrel or designed in part to be soldered into an existing state-of-the-art action block, thereby producing a new two piece solid barrel design. 
   In addition, side by side barrels, single barrels, pistol barrels, rifle barrels, and double rifle barrels can also be produced using the process of the present application. 
   The foregoing exemplary descriptions and the illustrative preferred embodiments of the present invention have been explained in the drawings and described in detail, with varying modifications and alternative embodiments being taught. While the invention has been so shown, described and illustrated, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope of the invention, and that the scope of the present invention is to be limited only to the claims except as precluded by the prior art. Moreover, the invention as disclosed herein may be suitably practiced in the absence of the specific elements which are disclosed herein.