Abstract:
The present invention is a method and apparatus for automatically attaching loops of a coil together at desired points. The apparatus comprises a frame, a rotatable barrel, wire separators, alignment fingers, a clipping rack further comprising pincers, and a clipping gun. The barrel, wire separators and fingers cooperate to attach the alternate loops together at desired points. The barrel is driven by a stepper motor to rotate a specific distance about a central axis. The wire separators, pincers, and clipping gun are driven pneumatically. The motor and pneumatics are controlled electronically.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates to a method and apparatus for deforming metal, specifically modifying barbed tape into concertina.  
       BACKGROUND  
       [0002]     Coiled barbed tape has long been known as a barrier. It is essentially a coil of steel wire that has razor blades attached every few feet. Each portion of the coil that forms a 360 degree circle is called a “loop” herein. For increased strength and improved ease of handling, the loops of barbed tape can be connected to each other at staggered points. The material having connected loops is referred to herein as concertina, to distinguish it from a coil of barbed tape in which the loops have not been connected, referred to herein as simply a coil.  
         [0003]     Historically, concertina is made by loading a coil of barbed steel wire onto a frame that rotates about a central axis. Then a man grabs a first loop of the coil and manually pinches it to the previous loop of the coil while simultaneously using a pneumatic gun to wrap a metal strip around the coils to attach them together. The metal strip is known in the art as a clip. Then, the man rotates the frame a given amount and grabs the first loop of the coil and clips it to the subsequent loop of the coil. The process results in alternate loops being attached to each other. This clipping-and-rotating is repeated until the entire coil is attached at desired points along the entire length of the coil. Loops attached five times are known as “5-clip” concertina in the art; “3-clip,” “7-clip” and “9-clip” configurations are also known in the art.  
         [0004]     The conventional manual method of making concertina is dangerous and slow. The barbs are literally as sharp as razor blades and therefore will easily slice through skin. The steel coil is under tension due to the helix configuration (like a Slinky®) and therefore difficult to handle. Further, even a short coil of barbed steel wire is very heavy.  
         [0005]     Therefore, it is an object of this invention to provide a faster and easier method and apparatus for clipping coils of barbed tape together to form concertina. It is another object to provide such method and apparatus to automate the connection of the loops of the coil of barbed tape.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is a method and apparatus for automatically attaching loops of a coil of barbed tape together at desired points. The preferred embodiment of the apparatus comprises a rotatable barrel, wire separators, a clipping assembly further comprising pincers and alignment fingers and a clipping gun. The components cooperate to attach the loops together at desired points. The barrel is driven by a stepper motor to rotate a specific distance about a central axis. The wire separators, fingers, pincers, and clipping gun are driven pneumatically. The motor and pneumatics are controlled with electronic switches. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  illustrates a coil of barbed wire of the prior art that has been expanded to form a barrier.  
         [0008]      FIG. 2  is a schematic illustration of a portion of coil and the attachment points of “5-clip” concertina.  
         [0009]      FIG. 3  illustrates a left side view of the apparatus.  
         [0010]      FIG. 4  illustrates a right side view of the apparatus.  
         [0011]      FIG. 5  shows a perspective view of a clip.  
         [0012]      FIG. 6  shows a perspective view of portions of two loops clipped together.  
         [0013]      FIG. 7  illustrates a left side view of the apparatus with a coil loaded onto the barrel.  
         [0014]      FIG. 8  shows is a detailed right side view of the clipping assembly, showing two loops clipped together.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]      FIG. 1  illustrates a coil  10  of barbed tape of the prior art that has been expanded to form a barrier.  FIG. 2  is a schematic illustration of a portion of coil  10 , namely three loops: the index loop, the loop previous to it and the loop subsequent to it. The dotted lines indicate where the loops will be attached to each other. The index loop is attached to the previous loop at attachment points  1 ,  3  and  5  and to the subsequent loop at attachment points  2  and  4 . For clarity of illustration, only the attachment points in the index loop are shown; the previous loop and the subsequent loop would have additional attachment points with their neighbors, if the coil was shown in its entirety.  
         [0016]      FIG. 3  illustrates a left side view of the preferred embodiment of the apparatus. The apparatus comprises a barrel  14 , wire separators  16 , a clipping rack  17  further comprising pincers  18  and alignment fingers  19 , and a clipping gun  20 . The barrel  14  is rotated around its lengthwise axis by a motor  15 . The motor  15  is capable of rotating the barrel a specific distance so that a desired point on each loop can be positioned under the pincers  18 . The preferred embodiment employs a stepper motor that is controlled electronically, as is known in the art.  
         [0017]     Each wire separator  16  extends through an aperture in the barrel  14  and can be retracted into the barrel  14 . Each wire separator  16  is moveable from one side of the aperture to the other. Preferably the wire separators are operated pneumatically and the pneumatics are controlled electronically. Alternatively, the wire separators may be operated mechanically or electronically.  
         [0018]      FIG. 4  illustrates a right side view of the apparatus to more clearly show the alignment fingers, namely the outer finger  41 , the mid finger  42 , and the back finger  43 . The alignment fingers  19  extend and retract through apertures in the barrel  14 . As with the fingers, preferably the alignment fingers are operated pneumatically, and the pneumatics are controlled electronically. Alternatively, the fingers may be operated mechanically or electronically.  
         [0019]     The loops of the coil are attached at desired points. The preferred embodiment attaches each loop five times, although the loops may be attached as many times as desired, for example to create 3-clip or 7-clip concertina. The attachment has to be robust to withstand the forces tending to pull the loops apart, inherently from the helix structure but also as the concertina is expanded to form a barrier. The loops can be attached together in several ways. The preferred embodiment uses a clip  50 , as shown in  FIG. 5 .  FIG. 6  shows portions of two loops clipped together. In the preferred embodiment, the clips are applied to the loops using a pneumatic clipping gun  20 . Clipping guns are available commercially from fencing suppliers. The loops may be attached in other ways, for example by welding, riveting, or crimping, each way using an attachment device specific to the way the loops are fastened to each other. For example, the attachment device for a weld would be a welder; a rivet gun for a rivet; or a crimper for crimping the loops together, all of which are available commercially.  
         [0020]     To attach the loops together, a coil  10  is loaded onto the barrel  14 . See  FIG. 7 . Once the coil  10  is loaded, the first two loops to be attached are aligned under the pincers  18 . The alignment is accomplished by the interaction and cooperation of the wire separators  16  and the alignment fingers  19 , depending on which loops are to be attached. It is convenient to think of the attachment taking place over three loops at a time as illustrated in  FIG. 2 : an index loop, the loop previous to it, and the loop subsequent to it. To attach all the loops of an entire coil, each loop incrementally becomes the index loop, until each of all loops has been attached to its neighbors at the desired points.  
         [0021]     Each wire separator  16  extends from its aperture at the appropriate side of the aperture to limit the movement of each loop and thus guide each loop in a desired direction along the axis of the barrel. Similarly, each of the alignment fingers extends and retracts through its aperture in the barrel to limit the movement of each loop and thus guide each loop in a desired direction along the lengthwise axis of the barrel. The result is that the appropriate loops can be aligned under the pincers  18  to be attached to each other. The alignment fingers  19  also lift the loops to be attached, as explained below.  
         [0022]     In one embodiment, the index loop and loop previous to it are selected and guided with the wire separators to pass under the pincers. Using at least one electronically-controlled alignment finger, the loops are aligned under pincers at the first desired attachment point on the coil. The index loop and previous loop are attached together by first pinching the loops together with the pincers then clipping them together with the clipping gun. This attachment routine for a clipping gun is defined in more detail below. The barrel is then rotated a given distance to align the loops under the pincers at a second desired point. This rotating, aligning and attaching is repeated until all the loops are attached to their neighbors.  
         [0023]     In order to use a clipping gun  20  as the attachment device, the loops have to be raised off the barrel so that the jaw of the clipping gun  20  can get under the loops to grasp them. In essence, the attachment routine lift the loops off the barrel, clips them, then lowers the now-clipped loops back to the barrel. This lifting and lowering is accomplished by extending one of the alignment fingers from the barrel to lift the loops off the barrel. Then the pincers are opened, lowered over the loops, and closed on the loops to securely hold them. Then the clipping gun is moved into position so that the jaw of the clipping gun  20  can grasp the raised loops. The clip is attached, clipping gun retracted, pincers opened, and the finger retracted, leaving the now-clipped loops resting on the barrel. Which loops are being attached will determine their position relative to the fingers and therefore which finger needs to be raised to lift the loops of the barrel.  FIG. 8  shows the outer finger  41  lifting the now-clipped loops  81  off the barrel  14 . The clipping gun  20  is retracted and the pincers  18  are opening to release the loops  81 . Timing electronics cause these actions to be coordinated.  
         [0024]     The attachment at the desired points takes place in any order. For example, the previous loop and index loop can be attached at one point, followed by attachment of the index loop and the subsequent loop at a second desired point, followed by attachment of the previous loop and the index loop again at a third desired point. This would require selecting, aligning, and rotating after each attachment. However, once the loops are attached to each other at even one point, it becomes more difficult to separate the loops from each other and select them for attachment. It is easier to separate the loops away from an attachment point that nearer to one. For this reason, wire separators are spaced around the circumference of the barrel to enable the selection and guiding to occur at different distances from an attachment point. It has been found to be most efficient, therefore, to attach all points on a given pair of loops before selecting a second pair of loops. Thus, the preferred embodiment attaches all the desired points on the previous loop and the index loop before moving on to attach all the desired points on the index loop and the subsequent loop. A specific example is illustrative:  
       EXAMPLE 1  
     Attaching Loops in a 5-Clip Configuration  
       [0000]    
       
         
           
              Rotate the barrel to a first desired attachment point; extend a first wire separator from the barrel to select and guide the first pair of loops (namely the index loop and the one previous to it); and execute the attachment routine, as described above, on the first pair of loops at the first desired point, using the mid finger to lift the loops;  
              Rotate the barrel to a third desired attachment point and when the clip is behind the first wire separator, retract the mid finger and extend a second wire separator from the barrel to select and guide the first pair of loops; execute the attachment routine on the first pair of loops at the second desired point, using the mid finger to lift the loops;  
              Rotate the barrel to a fifth desired attachment point and when the clip is behind the second wire separator, retract the mid finger and extend a third wire separator from the barrel to select and guide the first pair of loops; execute the attachment routine on the first pair of loops at the third desired point, using the mid finger to lift the loops;  
              Select a second pair of loops (namely the index loop and the one subsequent to it) by extending the outer finger from the barrel; shift the first wire separator to the other side of its aperture and extend it from the barrel to select and guide the second pair of loops;  
              Rotate the barrel to the starting point and when the clip is behind the third wire separator, retract the mid finger. 
 
 At this point the barrel has made one 360° rotation. 
 
              Rotate the barrel to a second desired attachment point; extend a fourth wire separator from the barrel to select and guide the second pair of loops, execute the attachment routine on the first pair of loops at the third desired point, using the mid finger to lift the loops;  
              Shift wire separator to the other side of its aperture to select and guide the second pair of loops;  
              Rotate the barrel to a fourth desired attachment point and when the clip is behind the fourth wire separator, retract the outer finger and extend the second wire separator from the barrel to select and guide the second pair of loops; execute the attachment routine on the second pair of loops at the fourth desired point, using the outer finger to lift the loops;  
              Rotate the barrel to the starting point and repeat the process for the next set of loops.  
           
         
       
     
         [0034]     While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the invention, but that the invention will include all embodiments falling within the scope of the appended claims.