Abstract:
A computer numerical control (cnc) bending machine used to bend and then cut a specific programmed profile from a long length of cable comprising: a base, a carriage, a bend head and a saw; the carriage includes a spindle to rotate the cable, the carriage is also able to transport the cable in a linear fashion; the bend head comprises a clamp and a wiper roller and a bend die; after a last bend is formed, the clamp and wiper roller are retracted away from the bend die; the carriage is then able to then transport the cable forward away from the saw, the spindle is then able to rotate the cable out of the plane of the bend, the carriage is then able to transport the cable back toward the saw; the saw is then able to sever the cable such that a last leg length adjacent to the last bend which is shorter than the fixed distance between the saw and the bend die.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. application Ser. No. 14/020,031, filed Sep. 6, 2013 in the U.S. Patent and Trademark Office. All disclosures of the document named above are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Aspects of the present invention relate to the cutting of semi-rigid coax cable on a computer numerical control (cnc) cable bending machine. More particularly, aspects of the present invention relates to the length of material remaining between the last formed bend and the adjacent end of the cable after the saw has severed the formed part from a long length of straight cable. 
         [0004]    2. Description of the Related Art 
         [0005]    Semi-rigid coax cable (cable) is used to transmit electrical signals. Having the ability to cut the cable accurately is important for the quality of the transmitted signal to remain high. For decades the cutting process of a bent profile has been accomplished by either a stand alone powered bench saw or a powered saw integrated into a cnc cable bending machine. The saw on a cable bending machine is mounted such that a fixed distance exists between the saw blade (cutting plane) and the center of a bend die. This distance is often attempted to be as short as possible. However, there is a minimum distance permissible before the saw blade starts to cut into the bend tooling. This has been a limitation of this type of cutting process for decades. This distance is often referred to in the cable bending industry as the minimum last leg length. The minimum last leg length therefore defines how short the last leg can be processed on a specific cnc bending machine. Thus, the last leg length is the length of the straight portion of the cable from the end of the cable to the bend that is formed therein. 
         [0006]    During the normal course of bending coax cable, a cnc bending machine often accepts a long length of semi-rigid coax cable to process. From this long length of cable, several individual parts can be fabricated provided that the cnc bending machine has an integrated saw as part of the function of the overall system. When a saw exists within the system, a typical user of the bending machine will program the machine to make one or more specific bends within a cable. After the last bend has been processed, the controller on the machine may instruct the user to cut the cable. Normally the system can move the cable forward after the last bend to make the cut, but the system has been unable to pull the cable backwards to make a cut because the last bend formed in the cable is wrapped (hooked) around the bend tooling. 
         [0007]    Some cables are designed with a last leg length less than the minimum allowable last leg length as specified by the manufacturer of the cable bending machine. When this happens, the user of the bending equipment who is fabricating the bent coax cable must perform a secondary trim operation to further remove material from the cable&#39;s end to meet the required last leg length. 
         [0008]    Over the years, Pines Technology (Westlake, Ohio) has built cnc cable bending equipment with an integrated saw to cut semi-rigid coax cable on a cnc bending machine. Their equipment, as described above, has a fixed distance from the plane of cut to the center of the bend die. This fixed distance determines the minimum last leg length that can be processed on the cable bender. It has never been considered obvious to backup and cut the cable because the last bend formed in the cable is wrapped (hooked) around the bend tooling. 
         [0009]    Likewise, Winton Machine (Suwanee, Ga.) has built cnc cable bending equipment with an integrated saw to cut semi-rigid coax cable. Their equipment, as described above as well, has a fixed distance from the plane of cut to the center of the bend die. This fixed distance determines the minimum last leg length that can be processed without using a secondary cutting operation. It has never been considered obvious to backup and cut the cable because the last bend formed in the cable is wrapped (hooked) around the bend tooling. Backing up would have a tendency to unbend the cable and thus result in a non-conforming profile. 
         [0010]    The hardship over the years when bending with an integrated cutting device has been to live with the minimum last leg length as specified by the machine tool builders and perform with a secondary trim operation as needed. The secondary trim operation adds to the cost of goods sold. 
         [0011]    U.S. Pat. No. 8,234,772 assigned to Schleuniger does provide for cutting a flexible cable while offering a means to move the cable forward and backwards prior to cutting. However, Schleuniger does not provide a means for bending in the same apparatus. Also. Schleuinger makes use of a shear type cut and a shear type cut has been known to damage the ends of semi-rigid coax cable. It would not have been obvious to add a bending operation to this type of equipment because the apparatus of the cutting process would get in the way of bending the most simplistic profile. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, it is an object of the present invention to reduce the minimum last leg length allowable on a cnc coax bending machine when the distance between the plane of cut and the center of the bend die is fixed. 
         [0013]    It is another object of the present invention to eliminate a secondary trimming operation. 
         [0014]    It is still another object of the present invention to allow a user to reduce the cost of goods sold by eliminating time consuming secondary trim operations. 
         [0015]    Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above objects and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which: 
           [0017]      FIG. 1  shows an isometric view of a cnc bending machine with a powered saw that is used to bend &amp; cut semi-rigid coax cable from a long length of straight cable; 
           [0018]      FIG. 2  shows an isometric close up of the bending head from  FIG. 1  with the carriage up close to the bend head assembly.  FIG. 2  also shows a bent cable residing in the plane of bend with the last bend still formed (hooked) around the bend die; 
           [0019]      FIG. 3  shows a side view of  FIG. 2 ; 
           [0020]      FIG. 4  shows an alternate isometric view close up of the bend head with the carriage up close to the bend head. In this view, the cable is rotated out of the plane of bend with the clamp die and wipe roller retracted allowing the cable to be rotated out of the plane of bend; 
           [0021]      FIG. 5  shows a top view of a bent cable laying in the plane of bend with its relation to the bend die right after a bend has been completed; 
           [0022]      FIG. 6  shows the cable rotated out of the plane of bend and retracted in the negative X direction with respect to the fixed position of the bend die. The cable is also shifted out in the positive Z direction, allowing the cable to clear the bend die as the cable retracts; and 
           [0023]      FIG. 7  shows an isometric view of  FIG. 6  where the cable is pulled back in the negative X direction, further showing the distance between the cut plane and the start of the last bend.  FIG. 7  also shows the cable shifted out in the positive Z direction, allowing the cable to clear the bend die as the cable retracts in the negative X direction. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0024]    Reference will now made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
         [0025]    With reference to  FIG. 1 , a cable bending machine  10  is shown. The cable bending machine  10  includes a base  11 , a carriage  12 , a saw  13 , and a bend head  14 . A base  11  includes a computer  16  and various switches  17 . 
         [0026]    An axis indicator  15  is shown to further describe the bending machine  10 . The axis indicator  15  is a three dimensional visualization aid and is not part of the bending machine  10 . The axis indicator  15  shows three arrows labeled X, Y, and Z. The positive directions of the X, Y, and Z axes are indicated by the pointed direction of each individual arrow. In general, a negative X direction is opposite a positive X direction. The same is true for the Y and Z directions. 
         [0027]    From  FIGS. 2 and 3 , a cable  27  is shown in a bent configuration. It is the purpose of the bending machine  10  to bend the cable  27  into a specific shape starting with a long straight cable  47 . The cable  47  is shown between a spindle  26  and a bend die  30 . The bend die  30  is fixed in position relative to saw the  13 . The cable  47  and the cable  27  are initially one continuous cable. The base  11  is used to support all the necessary electronics needed to provide for bending the cable  27 . 
         [0028]    The carriage  12  is a three axis device used to manipulate the cable  27  as it is being processed during a bending operation. The carriage  12  is able to transport the cable  47  forwards and backwards parallel to the X axis along a rail  25 . The carriage  12  supports the spindle  26 . The spindle  26  is able to grip the cable  47  and rotate about an axis parallel to the X axis. At certain times during a forming process, the cable  47  is held captive by spindle  26 . The spindle  26  is also able to shift the cable  47  in the negative and positive Z directions. 
         [0029]    The saw  13  includes a guard  28 , a saw blade  38 , and a saw support post  23 . The saw blade  38  is circular in nature and is powered to rotate about an axis parallel to the X axis. The saw support post  23  provides a foundation for the saw blade  38  during its normal course of operation. The saw support post  23  is attached to the base  11 . The saw blade  38  is able to translate (move) in a plane parallel to a plane that contains both the Y and Z axes. 
         [0030]    From  FIGS. 2, 3, and 4 , the bend head  14  includes the bend die  30 . The bend die  30  is held captive by a screw  29 . The screw  29  threads into a bolster  42 . The bolster  42  mounts to a bend head frame  24 . The bend head frame  24  is supported by the base  11 . 
         [0031]    Concentric with the bend die  30  is a spindle  20 . The spindle  20  is parallel to the Y axis. The spindle  20  is able to rotate about an axis parallel to the Y axis. The spindle  20  is prevented from linear motion. However, it is a bearing  21  that allows the spindle  20  to freely rotate about the axis parallel to the Y axis. Attached to the spindle  20  is a wiper base  33 . The wiper base  33  supports a wiper arm  34 . The wiper arm  34  supports a wiper roller  32 . The wiper roller  32  is held captive by a screw  31 . 
         [0032]    From  FIG. 2 , the wiper arm  34  is able to slide relative to the wiper base  33  in a direction parallel to the Z axis through the use of an air cylinder (not shown). As the spindle  20  rotates, so does the attached wiper base  33  and wipe arm  34 . As the spindle  20  rotates, the relative motion between the wiper base  33  and the wiper arm  34  is still permissible yet not always parallel to the Z axis. 
         [0033]    Also supported by the bend head frame  24  is a clamp base  36 . The clamp base  36  supports a clamp slide  35 . The clamp slide  35  supports a clamp  37 . The clamp  37  is able to move along an axis parallel to the Z axis. 
         [0034]    From  FIGS. 2 and 3 , the saw blade  38  and the screw  29  that locates the bend die  30  are separated by a fixed distance D in the X direction. The center of screw  29  is concentric with the bend die  30  as well as the spindle  20 . A line  40  is shown in  FIG. 3  and is considered to be concentric with the bend die  30 . The line  40  is parallel to the Y axis. A cut plane  39  is considered to be parallel to (and coincidental with) the saw blade  38  and perpendicular to the X axis. The distance D is considered to be the fixed distance from the saw blade  38  to the center of the bend die  30 , in the X axis direction. 
         [0035]      FIG. 5  shows the cable  47  and its relationship to the bend die  30  after a bend  43  has been formed in the cable  27 . The distance D is further depicted as the distance from the center of the bend die  30  to the cut plane  39 . In  FIG. 5 , the cable  47  is shown to be cut at a gap  44 . The gap  44  coincides with the cut plane  39  and the saw blade  38 . When cutting the cable  47 , the cut plane  39  is always parallel to the Y and Z axes. From  FIG. 5 , a last leg length  45  is shown to reside between a plane  41  and the gap  44 . The plane  41  coincides with one end of bend  43 . The plane  41  is always perpendicular to the X axis. 
         [0036]      FIG. 6  shows the cable  27 , which is a bent piece, in a new position relative to the bend die  30 . With the bend die  30  fixed in position relative to the saw blade  38 , the cable  27  is shown shifted in the negative X direction. By doing so, the bend  43  becomes closer to the cut plane  39 . Thus, a distance C from the cut plane  39  to the start of the bend  43  is less than the distance D. Now the last leg length  45  in  FIG. 6  is in a position to be cut shorter than the last leg length  46  as depicted in  FIG. 5 . 
         [0037]    From  FIGS. 6 and 7 , the spindle  26  and the cable  27  are shifted out in the positive Z directions away from the bend die  30 . 
         [0038]    From  FIGS. 6 and 7 , the cable  27  is repositioned to allow the bend  43  to be closer to the cut plane  39 . The cable  27  can only be repositioned by the spindle  26  prior to the saw blade  38  forming the gap  44  in cable  47 . 
         [0039]    In operation, from  FIGS. 1 through 3 , a long straight piece of the cable  47  is placed in the spindle  26 . The spindle  26  then grips the cable  47 . The carriage  12  and thus spindle  26  will then move in the x axis direction to present the cable  47  to the bend die  30 , the wiper roller  32 , and the clamp  37  for bend processing. With the cable  47  in position, the carriage  12  and the bend head  14  can make a series of computer coordinated moves to bend cable  27 . 
         [0040]    The, cable  27  is bent by the spindle  20  rotating the wiper roller  32  concentrically around the bend die  30 . All during this time the clamp  37  holds the cable  27  firmly against the bend die  30 . 
         [0041]    From  FIGS. 5 through 7 , after the last bend has been made, the controller can then get ready to cut or sever the formed part from the long length of the cable  47  concentrically located in the spindle  26 . In order to cut the last leg length  45  less than distance D, the following coordinated operations are performed. 
         [0042]    Starting from  FIG. 5 , the wiper roller  32  and the clamp  37  both retract away from the bend die  30 . With the spindle  26  firmly gripping the cable  47 , the carriage  12  advances the cable  47  forward in the positive X direction just enough for the cable  27  to clear the bend die  30 . Then, the spindle  26  rotates cable  27  out of the plane of the bend and about an axis parallel to the X axis. Then, the spindle  26  retracts, thereby pulling the cable  27  back with it a distance greater than the distance A. When retracting, the cable  27  is traveling in the negative X direction towards the saw blade  38 . 
         [0043]    From  FIGS. 6 and 7 , the cable  27  is now shown in one of numerous retracted positions where if the cable  27  is cut on the cut plane  39 , the length of the last leg  45  would be less than the fixed distance D. 
         [0044]    Once the cable  27  is in the retracted position, the saw blade  38  can descend in the negative Y direction, thus producing the gap  44 . Once the gap  44  is imparted in the cable  47 , cable  47  and cable  27  are consider severed, leaving the last leg length  45  less than the distance D. 
         [0045]    As an alternate way of operation, after the spindle  26  has rotated the cable  27  out of the plane of the bend, the cable  27  can shift out in the positive Z direction prior to being retracted in the negative X direction by spindle  26 . The amount of the shift out in the positive Z direction distance C, which is sufficient enough so that the cable  27 , including the bend, suredly clears the sides of the bend die  30  upon being retracted in the negative X direction. The benefit of shifting the cable  27  out in the positive Z direction is it can minimize any interference that may arise between the cable  27  and the bend die  30  as the spindle  26  pulls back on the bent cable  27  in the negative X direction. 
         [0046]    In the event the spindle  26  does not shift out prior to retracting the cable  27  in the negative X direction, the cable  27  would then have a tendency to flex out, or bow in the positive Z direction as the cable  27  is forced past the bend die  30 . This could cause the gap  44  to be somewhat not perpendicular to the cable  47 , and thus a square cut is not achieved at the end of the cable  27 . 
         [0047]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.