Abstract:
A device for making a shielded electrical wire comprising a first folding die that folds a first and second edge of a shield tape in an opposite direction from the central portion of the shield tape, a second folding die that wraps the shield tape around the insulated conductors and folds the first edge back over onto the central portion of the shield tape to form a receiving area, a third folding die that tightens the shield tape around the plurality of conductors while positioning the receiving area to receive a drain wire, a wire guide that installs a drain wire in the receiving area, and a closing die that closes the shield tape around the plurality of conductors and the drain wire to form an enclosure around the plurality of conductors with the second edge overlapping the receiving area at an outside surface of the enclosure, in order to better define the claimed invention.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 61/061,037, filed Jun. 12, 2008. The disclosures of that application is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a device of and method for manufacturing shielded wire and cable. More particularly, the present invention relates to a device of and method for applying longitudinal shield tape to electronic wire and cable using an edge folder to enclose a drain wire in an edge of the shield tape. 
     BACKGROUND OF THE INVENTION 
     Modern electronic wire and cable typically includes insulated electrical conductors, such as copper wire, bound together in a common protective jacket or sheath. The conductors are insulated from each other by coating them with an insulating material using an extrusion process, such as pressure extrusion or tube/sleeve extrusion. Under accepted industry standards, individual conductors are allowed to include a predetermined amount of defects or pin-holes in the insulation, which are measured by “spark” tests. Such imperfections are essentially unavoidable during the fabrication of the individual conductors and can result in “hi-pot” (high potential) test failures in cabled conductors if the current traveling through those conductors arcs with shield tape disposed around the conductors. 
     Shield tape is typically applied around cabled conductors to shield the conductors from the undesired effects of external influences, such as electromagnetic radiation. A variety of different constructions of shield tape have been applied around conductors in a number of different configurations to shield the conductors from such effects. Shield tape constructions generally include thin metallic foil layers, such as aluminum, laminated with a layer of insulating film, such as polyester, that form opposing sides of the shield tape. The layer of insulating film is provided to add strength and durability to the shield tape as well as to insulate the aluminum layer. A non-insulated grounding wire, or “drain” wire, is disposed on the aluminum side of the shield tape in electrical contact therewith to provide a low resistance electrical connection, or drain, to ground from substantially any point along the shield tape. 
     Shield tape is typically applied either helically wound around the conductors or longitudinally wrapped, i.e., “cigarette” wrapped, around the conductors. In both applications, the longitudinal edges of the shield tape generally must overlap one another by a relatively large amount, such as 25%, to prevent the shield from leaking radiation. The shield tape may be applied around the conductors either with the aluminum side facing outward away from the conductors and the drain wire disposed on the outside of the shield tape between the shield tape and the jacket or with the aluminum side facing inward toward the conductors and the drain wire disposed between the shield tape and the conductors. There are significant problems, however, with those conventional configurations of the shield tape and drain wire. 
     Shield tape is generally helically wound around the conductors to improve the flexibility of the cable. Helically wound shield tape, however, is prone to loosening and kinking at the overlapping edges when it is flexed during use or when drawn through various types of conduits during installation. Loosening and kinking of the shield tape may create spiral slots around the circumference of the shield that radiate interference rather than inductively coupling interference. The interference may radiate as much as 360° around the shield. Although it is also possible for slots to appear at the overlapping edges in cigarette wrapped shielding, those slots will be longitudinal and will radiate interference less effectively because they radiate interference only in the plane of the longitudinal slot. In addition, helically wound shield tape has a greater tendency to conform to the conductors than cigarette wrapped shield tape and is therefore less geometrically stable and more likely to form slots in the shielding. 
     Helically wound shield tape may be applied to the conductors during the cabling/stranding of the conductors. When shield tape is helically wound around the conductors during cabling/stranding, the shield tape is drawn over the conductors as the conductors rotate, or twist, together. To allow sufficient overlap of the shield tape edges and to ensure that the shield tape is tightly wound around the conductors, the twist lay length of the conductors must be short. Not only do short lay lengths require slower cabling/stranding speeds, they also require a greater amount of conductor material to make the same length of cable, which in turn results in a larger signal delay through the conductors. To apply helically wound shield tape around conductors with larger lay lengths with sufficient overlap and tightness, additional equipment must be used to rotate the shield tape around the conductors at a slower rate than the conductors are being twisted together. This extra machinery can be cost prohibitive. 
     Helically wound shield tape may also be applied to the conductors subsequent to the cabling/stranding of the conductors. When shield tape is helically wound around the conductors subsequent to cabling/stranding, the shield tape may be applied with sufficient overlap and tightness around the conductors irrespective of the conductors&#39; lay length. This process, however, requires that the conductors be collected on a reel after cabling/stranding and then paid off that reel into separate machinery that applies the shield tape, which requires additional man hours and multiple staging areas and is overall less efficient and more expensive than applying shield tape during cabling/stranding. 
     As discussed above, the drain wire may be applied between the shield tape and the jacket or between the shield tape and the conductors for either helically wound or cigarette wrapped conductors, depending on the side of the shield tape that faces the conductors. When the shield tape is applied with the aluminum side facing downward toward the conductors, the drain wire must be disposed between the conductors and the shield tape. To prevent the drain wire and/or shield tape from arcing with defects in the conductors and to prevent the drain wire from damaging the insulation on the conductors, a barrier layer of insulating material is typically applied around the conductors so that the aluminum side of the shield tape is in contact with the barrier layer and the drain wire is disposed therebetween. Applying an additional layer of insulating material around the conductors, however, requires additional material and machinery and greatly adds to the costs of manufacturing the cable. 
     In view of at least the above-identified problems, it is preferable to manufacture shielded cable by applying shield tape around the conductors in a cigarette wrapped configuration with the aluminum side of the shield tape facing outward away from the conductors. Even this configuration, however, creates several problems. For example, the dies used to fold the shield tape suffer significant wear when the aluminum side of the shield tape faces outward away from the conductors because the aluminum side of the shield tape is thereby placed in frictional contact with the dies as the shield tape moves through the dies. Although those dies are typically coated with a protective material to protect against excessive wear, the shield tape will still wear through the protective material when drawn through the dies at higher speeds. And, although pre-lubricated shield tape may be purchased, such shield tape can be cost prohibitive. 
     In addition, when the aluminum side of the shield tape faces outward away from the conductors, the drain wire must be disposed on the outside of the shield tape so the drain wire will be in electrical contact with the shield tape. Placing the drain wire outside the shield tape, however, creates a bulge in the otherwise flat surface of shield tape surrounding the conductors. If the cable jacket is pressure extruded over the assembly, the jacket will fill in around the drain wire and cause a groove to form on the inside of the jacket and/or a ridge to form on the outside of the jacket. And, if the jacket is tube/sleeve extruded over the assembly, the cable jacket will stretch around the drain wire and cause a ridge to form on the outside of the jacket. A groove on the inside of the jacket compromises the integrity of the cable by creating a thinner portion of jacket extending the length of the jacket, and a ridge on the outside of the jacket will compromise the integrity of the cable by not only adversely affecting the aesthetics of the cable, but also by making it more difficult to draw the cable through various types of conduits during installation. 
     Accordingly, there is a need for a device of and method for manufacturing shielded cable that allows the conductors to be shielded in a cigarette wrapped configuration, allows the drain wire to be on the outside of the shield tape without forming a ridge, and minimizes the amount of leakage in the shield. Further, there is a need to manufacture such a cable without causing excessive wear to the folding dies and while reducing the amount of additional cable material, man hours, work space and machinery required to shield the cable. 
     SUMMARY OF THE INVENTION 
     Accordingly, to solve at least the above problems and/or disadvantages and to provide at least the advantages described below, a non-limiting object of the present invention is to provide a shielded cable and device of and method for making same that includes a first folding die configured to fold a first edge of a shield tape a first direction from a central portion of the shield tape and to fold a second edge of the shield tape a second direction opposite to the first direction from the central portion of the shield tape, a second folding die configured to wrap the shield tape around at least two insulated conductors to apply a fold to the first edge of the shield tape so as to fold the first edge back over onto the central portion of the shield tape to form a receiving area, a third folding die configured to tighten the shield tape around the plurality of conductors while positioning the receiving area to receive a drain wire, a wire guide configured to install a drain wire in the receiving area, and a closing die configured to close the shield tape around the plurality of conductors and the drain wire to form an enclosure around the plurality of conductors with the second edge overlapping the receiving area at an outside surface of the enclosure. 
     These and other objects of the invention, as well as many of the intended advantages thereof, will become more readily apparent when reference is made to the following description, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an orthogonal view illustrating a non-limiting exemplary embodiment of a shielding device according to the present invention; 
         FIG. 2A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a first folding die of the shielding device according to the present invention; 
         FIG. 2B  is a cross-sectional view illustrating a shield tape folded by the first folding die of  FIG. 2A ; 
         FIG. 3A  is an orthogonal view illustrating a non-limiting exemplary embodiment of the second folding die of the shielding device according to the present invention; 
         FIG. 3B  is a cross-sectional view illustrating the shield tape in a die and folded around a pair of insulated conductors by the second folding die of  FIG. 3A ; 
         FIG. 4A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a third folding die of the shielding device according to the present invention; 
         FIG. 4B  is a cross-sectional view illustrating the shield tape in a die and folded around the pair of insulated conductors by the third folding die of  FIG. 4A ; 
         FIG. 5A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a wire guide of the shielding device according to the present invention; 
         FIG. 5B  is a cross-sectional view illustrating the shield tape with a drain wire installed therein by the wire guide of  FIG. 5A ; 
         FIG. 6A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a wire guide of the shielding device according to the present invention; 
         FIG. 6B  is a cross-sectional view illustrating the shield tape with a drain wire installed therein by the wire guide of  FIG. 6A ; 
         FIG. 7A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a guide block of the shielding device according to the present invention; 
         FIG. 7B  is a cross-sectional view illustrating the shield tape wrapped around the pair of insulated conductors and the drain by the guide block of  FIG. 7A ; 
         FIG. 8A  is an orthogonal view illustrating a non-limiting exemplary embodiment of a closing die of the shielding device according to the present invention; and 
         FIG. 8B  is a cross-sectional view illustrating a wrapped assembly closed by the closing die of  FIG. 8A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to non-limiting embodiments of the present invention by way of reference to the accompanying drawings, wherein like reference numerals refer to like parts, components and structures. 
     Turning to the figures,  FIG. 1  shows a cable shielding device  100  according to an embodiment of the present invention. The cable shielding device  100  may include a first folding die  102 , a second folding die  104 , a third folding die  106 , a wire guide  108 , a guide block  110 , and a closing die  112 . The various elements of the cable shielding device  100  operate in tandem to apply a shield tape  114  around at least two insulated conductors  116  and install an un-insulated conductor, or drain wire,  118  within a fold in the shield tape  114 . 
     The first folding die is adapted to apply a Z-fold to the shield tape  114 . The second folding die  104  is adapted to pre-form the shield tape  114  by beginning to tighten the shield tape  114  around the insulated conductors  116  and beginning to crease part of the Z-fold where the drain wire  118  is installed. The third folding die  106  is adapted to position the shield tape  114  for installation of the drain wire  118 , to tighten the shield tape  114  further around the insulated conductors  116 , and to maintain the orientation of the shield tape  114  so it closes properly after the drain wire  118  is installed. The wire guide  108  is adapted to install the drain wire  118  in the J-fold  306  ( FIG. 3B ) formed in the shield tape  114  by the first folding die  102 , the second folding die  104 , and the third folding die  106 . The guide block  110  is adapted to maintain the shield tape  114  wrapped around the insulated conductors  116  and the drain wire  118  as they travel from the wire guide  108  to the closing die  112 . The closing die  112  is adapted to close the shield tape  114  around the insulated conductors  116  and the drain wire  118  prior to jacketing the wrapped assembly  120 . 
     As illustrated in  FIG. 2A , the first folding die  102  includes a top portion  200  and a bottom portion  202  that are adapted to mate together and form a folding aperture  204  that extends therebetween. The folding aperture  204  includes a central portion  206 , an upward folding portion  208 , a downward folding portion  210 , an upper lip portion  212 , and a lower lip portion  214 . The central portion  206  is positioned substantially in the center of the folding die  102 . The upward folding portion  208  extends substantially perpendicular to the central portion  206  in an upward direction at one side of the central portion  206  and the downward folding portion  210  extends substantially perpendicular to the central portion  206  in a downward direction at the other side of the central portion  206  so that the folding aperture is formed substantially in the shape of a “Z”. The upper lip portion  212  is disposed in the upward folding portion  208  and extends substantially perpendicular to the upward folding portion  208 . The lower lip portion  214  is disposed in the downward folding portion  210  and extends substantially perpendicular to the downward folding portion  210 . 
     As illustrated in  FIG. 2B , one side of the shield tape  114  receives an upward fold  216  from the upward folding portion  208  and the other side of the shield tape  114  receives a downward fold  218  from the downward folding portion  210  when the shield tape  114  is drawn through the folding aperture  204  of the first folding die  102 . The central portion  206  of the folding aperture  204  is aligned in the same plane in which the shield tape  114  is aligned as the shield tape  114  is drawn through the first folding die  102 . The shield tape&#39;s central portion  220  remains in that plane as the shield tape  114  receives the upward fold  216  and the downward fold  218  from the first folding die  102 . A first crease  222  is formed where the upward fold  216  extends upward from the shield tape&#39;s central portion  220  and a second crease  224  is formed where the downward fold  218  extends downward from the shield tape&#39;s central portion  220 . Accordingly, the cross section of the shield tape  114  is folded in substantially the shape of a “Z” with a first edge  226  of the shield tape  114  at the top of the upward fold  216  and a second edge  228  of the shield tape  114  at the bottom of the downward fold  218 , i.e., the first folding die  102  applies a “Z-fold” to the shield tape  114 . 
     The upper lip portion  212  prevents the upward fold  216  from extending too far upward into the upward folding portion  208  by providing a physical barrier beyond which the first edge  226  of the shield tape  114  cannot extend. The lower lip portion  214  prevents the downward fold  218  from extending too far downward into the downward folding portion  210  by providing a physical barrier beyond which the second edge  228  of the shield tape  114  cannot extend. Accordingly, the upper lip portion  212  and the lower lip portion  214  work in conjunction to maintain the shield tape  114  substantially centered in the first folding die  102  as the shield tape  114  is drawn through the first folding die  102 . 
     As also illustrated in  FIG. 2B , the shield tape  114  includes an insulating layer  230  and a conductive layer  232 . As the shield tape  114  is drawn through the first folding die  102 , the insulating layer  230  is disposed in the upward direction, i.e., toward the top portion  200 . That allows the insulated conductors  116  to be drawn over the shield tape  114  and wrapped from underneath such that the conductive layer  232  of the shield tape  114  is disposed on the outside of the wrapped assembly  120 . Because the conductive layer  232  may be metallic, such as aluminum, and may come in contact with the first folding die  102  as the shield tape  114  is drawn through the first folding die  102 , the first folding die  102  is formed from a low wear material, such as plastic, to prevent excessive wear from such contact and eliminate the need for pre-lubricated shield tape. The insulating layer  230  may be polyester or the like. 
     The second folding die  104  is adapted to pre-form the shield tape  114 . As illustrated in  FIG. 3A , the second folding die  104  includes a stabilizing structure  300  and a pre-forming tube  302 . The pre-forming tube  302  is disposed substantially in the middle of the stabilizing structure  300 . The stabilizing structure  300  is adapted to maintain the pre-forming tube  302  in alignment with shield tape  114  as it is drawn through the cable shielding device  100 . The pre-forming tube  302  is an elongated member with a substantially cylindrical orifice  304  extending therethough. The pre-forming tube  302  is formed from a low wear material, such as poly tubing, to prevent excessive wear from frictional contact with the conductive layer  232  of the shield tape  114 . 
     As illustrated in  FIG. 3B , both the shield tape  114  and the insulated conductors  116  are drawn through the second folding die  104 . The cylindrical orifice  304  of the pre-forming tube  302  pre-forms the shield tape  114  by causing the shield tape&#39;s central portion  220  to form an upward curve around the insulated conductors  116  and by biasing the upward fold  216  and the downward fold  218  toward the center of that curve. The curve formed by the central portion  220  is of substantially the same diameter as the circular cross section of the cylindrical orifice  304 . As the circular cross section of the cylindrical orifice  304  biases the upward fold  216  toward its center, the upward fold  216  begins to align with the curve of the shield tape&#39;s central portion  220 , which substantially reduces the definition of the first crease  222 . And, as the circular cross section of the cylindrical orifice  304  biases the downward fold  218  toward its center, the downward fold  218  is caught between the wall of the cylindrical orifice  304  and the shield tape&#39;s central portion  220  so that the shield tape  114  becomes folded onto itself. By folding the shield tape  114  onto itself in that manner, a fold is created in the shield tape  114  substantially in the shape of a “J”, i.e., the second folding die  104  applies a “J-fold”  306  to the shield tape  114 , which forms a receiving area in the shield tape  114  for the drain wire  118 . 
     The third folding die  106  is adapted to position the shield tape  114  for installation of the drain wire  118  and to tighten the shield tape  114  further around the insulated conductors  116  while maintaining the orientation of the shield tape  114  so it closes properly after the drain wire  118  is installed. As illustrated in  FIGS. 4A and 4B , the third folding die  106  includes a top portion  400  and a bottom portion  402  that are adapted to mate together to form a folding aperture  404  that extends therebetween. The folding aperture  404  is substantially cylindrical except that it includes a guide lip  406  protruding into a portion thereof and extending its length. The guide lip  406  includes a curved wall  408  that smoothly transitions into the cylindrical wall of the folding aperture  404  and a flat wall  410  that forms a notched out portion, or guide groove,  412  extending substantially perpendicular from the cylindrical wall of the guiding aperture  404 . The third folding die  106  is preferably formed from a low wear material, such as plastic, to prevent excessive wear from frictional contact with the conductive layer  232  of the shield tape  114 . 
     As illustrated in  FIG. 4B , as the shield tape  114  is drawn through the third folding die  106  and the guiding aperture  404  tightens the shield tape  114  around the insulated conductors  116 , the first edge  226  of the shield tape  114  is guided in the notched out portion  412  of the guide lip  406  and the J-fold  306  is guided by the curved wall  408  of the guide lip  406 . By guiding the first edge  226  in the notched out portion  412  and guiding the J-fold  306  with the curved wall  408 , the guide lip  406  positions the J-fold  306  for installation of the drain wire  118  while maintaining the proper orientation between the first edge  226  and the J-fold  306  so the first edge  226  will overlap the J-fold  306  when the shield tape  114  is closed by the closing die  112 . 
     The wire guide  108  is adapted to install the drain wire  118  in the J-fold  306 . As illustrated in  FIGS. 5A and 5B , the wire guide  108  may be in the form of a guide tube  500 . The guide tube  500  includes a substantially cylindrical orifice  502  and an inserting portion  504 . The cylindrical orifice  502  extends axially through the guide tube and is adapted to receive the drain wire  118  therein so that the drain wire  118  can slide therethrough as it is installed in the J-fold  306  formed in the shield tape  114 . The inserting portion  504  is disposed at a distal end of the guide tube, is chamfered substantially in the shape of a “V”, and is adapted to be disposed inside the J-fold  306  of the shield tape  114  where it installs the drain wire  118  as the shield tape  114  and insulated conductors  116  are drawn past the guide tube  500 . The guide tube  500  may be installed on an axis at an angle “A” to the movement of the shield tape  114  and insulated conductors  116  through the cable shielding device  100 . The angle “A” is preferably concave towards the direction from which the shield tape  114  and insulated conductors  116  are being drawn. The guide tube  500  may be mounted on an adjustable pivot point  506  at an end opposite the inserting portion  504  to provide for adjustment of the angle “A” at which the drain wire  118  is installed in the J-fold  306 . The guide tube  500  is preferably formed from stainless steel. 
     In the alternative, as illustrated in  FIGS. 6A and 6B , the wire guide  108  may be in the form of a guide wheel  600  that is rotatably disposed on a central axis  602  and includes a guide surface  604  disposed along the perimeter thereof. The guide surface  604  is adapted to receive the drain wire  118  therein as the drain wire  118  moves in a circular direction around the guide wheel  600 . The drain wire  118  is guided into in the guide surface  604  by a guide arm  606  as the drain wire  118  is drawn through the cable shielding device  100 . A distal edge of the guide wheel  600  is disposed inside the J-fold  306  of the shield tape  114  where it installs the drain wire  118  as the shield tape  114  and insulated conductors  116  are drawn past the guide wheel  600 . The guide wheel  600  is preferably formed from stainless steel. 
     The guide block  110  is adapted to maintain the shield tape  114  wrapped around the insulated conductors  116  and the drain wire  118  as they travel from the wire guide  108  to the closing die  112 . As illustrated in  FIG. 7A , the guide block includes a top portion  700  and a bottom portion  702  that are adapted to mate together to form a guiding aperture  704  that extends therebetween. The guiding aperture  704  is substantially cylindrical and is of a diameter at least as small as the overall diameter of the guiding aperture  404  of the third folding die  106  so that the shield tape  114  will remain wrapped around the insulated conductors  116  and the drain wire  118  as they travel from the wire guide  108  to the closing die  112 . The guiding aperture  704  may also be substantially conical with the diameter decreasing from at least as small as the overall diameter of the guiding aperture  404  of the third folding die  106  to a diameter at least as small as the tubular central portion  802  ( FIG. 8 ) of the closing die  112  so that the shield tape  114  is progressively closed around the insulated conductors  116  and the drain wire  118  as they are drawn through the guide block  110 . 
     As illustrated in  FIG. 7B , as the shield tape  114 , insulated conductors  116 , and drain wire  118  are drawn through the guide block  110 , the shield tape  114  at least maintains its position around the insulated conductors  116  and the drain wire  118  as was established by the third folding die  106 , but preferably begins to wrap more tightly around the insulated conductors  116  and the drain wire  118 . As the shield tape  114  begins to close more tightly around the insulated conductors  116  and the drain wire  118 , the first edge  226  of the shield tape  114  begins to move over the J-fold  306  and the drain wire  118 . Accordingly, the guide block  110  maintains the shield tape  114  wrapped around the insulated conductors  116  and the drain wire  118  as they travel from the wire guide  108  to the closing die  112 . The guide block  110  may not be necessary where the closing die  112  is placed close enough to the third wire guide  108  that the drain wire  114  will not begin to open a detrimental amount when traveling from the wire guide  108  to the closing die  112 . 
     The closing die  112  is adapted to close the shield tape  114  around the insulated conductors  116  and the drain wire  118  prior to jacketing the wrapped assembly  120 . As illustrated in  FIG. 8A , the closing die  112  includes a receiving end  800 , a tubular central portion  802 , and an exiting end  804 . A closing orifice  806  extends through each of the receiving end  800 , tubular central portion  802 , and exiting end  804  of the closing die  112 . The cross section of the closing orifice  806  is sufficiently small to close the shield tape  114  down around the insulated conductors  116  and drain wire  118  as they pass through the closing die  112 . Preferably, the cross section of the closing orifice  806  becomes progressively smaller as it extends from the receiving end  800  to the exiting end  804  so that the diameter of the wrapped assembly  120  is progressively compressed as the wrapped assembly  120  is drawn through the closing die  112 . 
     The receiving end  800  of the closing die  112  is of a substantially larger diameter than the tubular central portion  802  such that a stepped portion  808  is formed at the transition between the two respective diameters. The stepped portion  808  is adapted to interface with the cross-head tip of an extruder and connect the closing die  112  thereto. The tubular central portion  802  is of a sufficient length to extend through the cross-head tip so the wrapped assembly  120  can be jacketed as it exits the exiting end of the closing die  112 . The closing die  112  is preferably formed from a low wear material, such as plastic, to prevent excessive wear from frictional contact with the conductive layer  232  of the shield tape  114 . 
     As illustrated in  FIG. 8B , as the closing die  112  closes the shield tape  114  around the insulated conductors  116  and drain wire  118 , the walls of the closing orifice  806  close the J-fold  306  around the drain wire and guide the first edge  226  of the shield tape  114  over the J-fold  306  to create an overlap  810  of the shield tape  114 . The wrapped assembly  120  takes on the cross-sectional shape of the closing orifice  806  as it is drawn through the closing die  112 . The cross-sectional shape of the closing orifice  806  may be changed to suit the desired shape of the wrapped assembly  120 . 
     In operation, the shield tape  114  is drawn through the first folding die  102  where it receives a “Z-fold”. The width of the central portion  206  of the first folding die&#39;s  102  folding aperture  204  may be changed according to the width of the shield tape  114  to ensure the proper amount of overlap  810  of the edges  226  and  228  of the shield tape  114  when it is closed around the insulated conductors  116  by the closing die  112 . For example, by centering the shield tape  114  as it passes through the first folding die  102  and sizing the central portion  206  of the folding aperture  204  to be about two thirds the width of the shield tape, a 25% overlap of the first edge  226  and the second edge  228  of the shield tape is ensured. That is because the upward fold  216  and the downward fold  218  will each be approximately one sixth the width of the shield tape&#39;s central portion  206  (⅙÷⅔=25%). By ensuring the proper amount of overlap, more efficient cable shielding is produced. Moreover, the amount of overlap can be adjusted to ensure that the first edge  226  extends beyond the second edge  228 . In addition, the first edge  226  may be folded back onto the upward fold  216  and towards the second edge  228  to make contact therewith so as to maintain electrical contact between the two edges  226  and  228 , which decreases leakage and further improves high frequency performance. 
     As the Z-folded shield tape  114  exits the first folding die  102 , a plurality of insulated conductors  116  are brought into close proximity of the shield tape&#39;s central portion  206  on the side of the shield tape  114  on which the insulating layer  230  is disposed. The shield tape  114  and insulated conductors  116  then enter the second folding die  104 , where the shield tape  114  is pre-formed around the insulated conductors  116  with the conductive layer  232  facing outward away from the insulated conductors  116 . Because the shield tape  114  is wrapped around the insulated conductors  116  with the conductive layer  232  facing outward away from the insulated conductors  116 , the shield tape  114  can be disposed between the drain wire  118  and the insulated conductors  116  so that no additional barrier layer is required between the shield tape  114  and the insulated conductors to protect them from failures, such as those measured by “hi-pot” (high potential) tests. The elimination of a need for an additional barrier layer reduces the manufacturing costs associated with shielding the insulated conductors  116 . 
     The pre-forming tube  302  of the second folding die  104  pre-forms the shield tape  114  by folding the downward fold  218  over onto the shield tape&#39;s central portion  220  to create the J-fold  306  in which the drain wire  118  is subsequently installed. In addition to wrapping around the drain wire  118 , the J-fold  306  ensures that neither the first edge  226  nor the second edge  228  of the shield tape  114  will come into electrical contact with or electrically arc with the insulated conductors  116 . Because J-fold  306  folds the second edge  228  of the shield tape  114  back onto the shield tape&#39;s central portion  220 , the second edge  228  is physically separated from the insulated conductors  116  by the shield tape&#39;s central portion  206 , i.e., the shield tape&#39;s central portion  206  is disposed between the second edge  228  and the insulated conductors  116 . And, because the first edge  226  overlaps the other side of the shield tape  114  when the closing die  112  closes the shield tape  114  around the insulated conductors  116  and drain wire  118 , the first edge  226  is also physically separated from the insulated conductors  116  by the shield tape&#39;s central portion  206  when the closing die  112  closes the shield tape  114  around the insulated conductors  116 . That configuration ensures that the insulated conductors  116  are surrounded only by the insulating layer  230  of the shield tape  114 , which greatly reduces the risk of hi-pot test failures. 
     The pre-forming tube  302  of the second folding die  104  also pre-forms the shield tape  114  by beginning to remove the first crease  222 . As the second folding die  104  begins to curve the shield tape&#39;s central portion  220  around the insulated conductors  116 , the shield tape&#39;s central portion  220  begins to move into the same plane as the upward fold  216  at the first crease  222 . Although the definition of the first crease  222  is substantially reduced by the second folding die  104 , the internal stresses imparted on the shield tape  114  at the first crease  222  when it was Z-folded by the first folding die  102  act to prevent the first edge  226  from folding over onto the insulated conductors  116  prematurely so that the J-fold  306  can be folded under the first edge  226  by the closing die  112  after the drain wire  118  is installed therein. 
     After the pre-formed shield tape  114  and partially wrapped insulated conductors  116  exit the second folding die, they enter the folding aperture  404  of the third folding die  106 . The folding aperture  404  of the third folding die  106  further tightens the shield tape  114  around the insulated conductors  116 . While further tightening the shield tape  114  around the insulated conductors  116 , the guide lip  406  of the third folding die  106  positions the J-fold  306  for installation of the drain wire  118  while maintaining the proper orientation between the first edge  226  and the J-fold  306  so that the first edge  226  will overlap the J-fold  306  when the shield tape  114  is closed by the closing die  112 . 
     After the third folding die  106  further closes the shield tape  114  around the insulated conductors  116  and properly positions the J-fold  306 , the wire guide  108  installs the drain wire  118  in the J-fold  306  as the shield tape  114  and insulated conductors  116  are drawn past the wire guide  108 . The drain wire  118  is drawn through the cable shielding device  100  with the shield tape  114  and insulated conductors  116 . When the drain wire  118  is installed in the J-fold  306 , it is disposed between the conductive layer  232  of the downward fold  218  and the conductive layer  232  of the shield tape&#39;s central portion  220 . By surrounding the drain wire  118  with conductive material in this manner, the drain wire  118  makes better electrical contact with the shield tape  114  than conventional drain wires that are merely installed between the shield tape and an insulating layer, such as the cable jacket. 
     With the drain wire  118  installed in the J-fold  306 , the shield tape  114 , the insulated conductors  116 , and the drain wire  118  are all drawn through the guide block  110 , which maintains the shield tape  114  wrapped around the insulated conductors  116  and the drain wire  118  as they travel from the wire guide  108  to the closing die  112 . As the shield tape  114 , insulated conductors  116 , and drain wire  118  are drawn through the closing die  112 , the shield tape  114  is closed around the insulated conductors  116  and the drain wire  118 . And, because the guide block  110  may have a guiding aperture  704  that is substantially conical with a diameter that decreases to at least as small as the diameter of the closing orifice  806 , much or all of the closing of the shield tape can be performed by the guide block  110  prior to the shield tape  114 , insulated conductors  116 , and drain wire  118  entering the closing die  112 . As the shield tape  114  is closed around the insulated conductors  116  and the drain wire  118 , a smooth transition is created over the drain wire  118  when the first edge  226  of the shield tape  114  is moved over to overlap the J-fold  306 . The smooth transition of shield tape  114  over the drain wire  118  substantially removes any ridge that would otherwise be created on the wrapped assembly  120  if the drain wire  118  were disposed on the opposite side of the shield tape  114  from the insulated conductors  116 . By removing the ridge from the outside of the wrapped assembly  120 , problems with jacketing and installation can be eliminated. 
     The closing die  112  can be inserted directly to an extruder cross-head so that the wrapped assembly  120  is jacketed as it exits the closing die  112 . As the extruder jackets the wrapped assembly  120 , a rip cord (not shown) can be installed between the wrapped shield tape  114  and the jacketing so that the jacketing can more easily be removed from the wrapped assembly  120  in the field. Alternatively, a rip cord may be installed between the insulated conductors  116  and the shield tape  114 . 
     Accordingly, the cable shielding device  100  of the present invention can be utilized in tandem with an extruder and other cabling equipment, such as an inside-out cabler, in a continuous process. And, because the cable shielding device  100  is able to wrap shielding on insulated conductors that have already been cabled/stranded, it can be installed between a cabling/stranding machine and an extruder, thereby reducing what would otherwise be a two-step process into a one-step process. Thus, the present invention allows a single operator to complete an entire cabling/stranding, shielding and jacketing process without having to place cabled/stranded conductors on a reel and pay them back off through the shielding device  100  and/or an extruder. 
     The foregoing description and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not intended to be limited by the preferred embodiment. Numerous applications of the invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. For example, although the shield tape  114  preferably includes an insulating layer  230  and a conductive layer  232 , the shield tape  114  may be only a single layer that is either dielectric or conductive; or, alternatively, the shield tape  114  may be more than two layers of insulating and conductive material in any suitable arrangement.