Abstract:
Apparatus and method are disclosed that are used to precisely remove segments of one or more layers of a laminate to expose a portion of a targeted interior layer. 
     Resistance measurements between a point in the laminate where material is being removed and a second point in the laminate are used to control the removal process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. Provisional Patent Application No. 61/893,990, filed Oct. 22, 2013, entitled “Apparatus and method for removal of a segment of a layer of a multi-layer laminate” the contents of which are hereby incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present invention relates generally to power tools and tool bits. The invention has particular application in stripping away portions of one or more layers of a laminate in order to expose a desired portion of a targeted interior layer. 
       BACKGROUND OF INVENTION 
       [0003]    Laminations comprising layers of the same or different materials are used in the construction of various items for a number of reasons. For example, beams made of laminated veneer lumber (lvl) are commonly recognized to be stronger than conventional lumber of the same dimensions. Conventional electrical wires and cables typically are laminates as well and comprise an inner conductor covered by one or more insulating layers. Laminates are now frequently used in the manufacture of flexible printed circuit boards and flat cables. Flat cables may be used instead of conventional communication cables, such as HDMI cables, as well as power supply cables such as extension cords. Flat cables have a much lower profile than conventional cables and can more easily be blended into the surface of walls and under or around obstructions. 
         [0004]    Flat cables typically are comprised of very thin alternating layers of conductive and insulating materials. However, because the layers are thin, it is difficult to strip away unwanted layers of, for example, an insulating material in order to expose and make electrical contact with a targeted conductive layer. Conventional wire stripping tools are not effective in quickly removing a segment of one or more layers of a flat cable without damaging the other layers that are beneath the layer or layers being partially removed. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of this invention to provide a method and an apparatus for removing a limited segment of one or more layers of a laminate to expose an inner targeted layer by using a tool bit without damaging any remaining layers. During the removal process, the electrical resistance between two or more points in the laminate is monitored. Tool bits may be rotary tool bits or non-rotary tool bits. The electrical conductivity or resistance may be measured between, for example, two points on the surface being contacted by the tool bit. This measurement is made using two or more tool face contacts. Alternatively, the electrical conductivity or resistance may be measured between a point or points on the surface being contacted by the tool bit and another point that is at a convenient distance from the tool bit. It is also an object of this invention to use resistance or conductivity measurements to control the amount of material being removed and/or the rate at which material is removed by the tool bit. 
         [0006]    It is another object of the invention to remove a segment of one or more layers of a flat electrical or communication cable so that a certain area of the surface of a conductive, internal targeted layer is exposed. 
         [0007]    It is a further object of this invention to provide a tool kit for removing segments of layers of a flat cable so that a selected segment of a conductive targeted layer is exposed. The kit comprises a tool bit with one or more tool face contact sensor pins that are configured to make electrical contact with the surface of material being removed. Two or more tool face contact sensor pins may be used to measure the electrical resistance between two points on the surface where material is being removed, by the tool bit, during the removal process. Alternatively, one or more tool face contact sensor pin(s) may be used to measure the electrical resistance between one or more points on the surface where material is being removed and a point that is at a convenient distance from the tool bit where material is not being removed by the tool bit. As a further alternative, the tool face itself may be used as an electrical contact and used to measure the electrical resistance between the surface where material is being removed by the tool bit and a point that is at a convenient distance from the tool bit where material is not being removed by the tool bit. During the removal process, the electrical resistance between two or more selected points is monitored. Based on the value of the resistance measurements obtained, the material removal process is controlled to automatically interrupt or alter the speed of the removal process. Alternatively or additionally, the kit may be configured to inform the tool operator when a certain electrical resistance or change in electrical resistance is achieved. The operator may be informed by, for example, visual, tactile or auditory signals. For example, a light may be illuminated or an alarm sounded when a certain resistance or change in resistance is detected. 
         [0008]    It is yet another object of the invention to provide a kit for the stripping of segments of one or more layers of a laminate where a guide/clamp mechanism is used to maintain a tool bit in a desired position relative to a surface of the laminate. Also provided is a power tool for driving the tool bit. 
         [0009]    The tool kit may also be configured with a vacuum or compressed gas system to remove or blow away debris produced during the material removal process. It is preferred that such debris be removed from at least the points where resistance measurements are being made, i.e. the vicinity of the electrical tool face contact sensor pins. 
         [0010]    It is a further object of this invention to mark a flat cable with markings as an aid for the proper relative positioning and alignment of a material removal tool bit and devices for guiding the tool bit during the removal process. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing summary, as well as the description of the embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the embodiments of the present inventions, and to explain their operation, drawings of preferred embodiments and schematic illustrations are shown. It should be understood, however, that the invention is not limited to the precise arrangements, variants, structures, features, embodiments, aspects, methods, advantages, improvements and instrumentalities shown, and the arrangements, variants, structures, features, embodiments, aspects, methods, advantages, improvements and instrumentalities shown and/or described may be used singularly in the apparatus or method or may be used in combination with other arrangements, variants, structures, features, embodiments, aspects, methods and instrumentalities. In the drawings: 
           [0012]      FIG. 1 a    is an illustration, showing a perspective view of a flat cable of the prior art, comprising two or three layers at various parts of the cable.  FIG. 1 b    shows a cross-section view of the cable in  FIG. 1   a.    
           [0013]      FIG. 2 a    is an illustration showing a side-view of an embodiment of a rotary tool bit with tool face contact sensor pins configured according to the invention.  FIG. 2 b    shows a bottom view of the tool bit in  FIG. 2 a   .  FIG. 2 c    shows a partial cross-section side-view of the tool bit in  FIG. 2 a   .  FIG. 2 d    shows an enlarged view of the sectioned portion of  FIG. 2   c.    
           [0014]      FIGS. 3 a -3 b    are illustrations showing use of the tool bit of  FIG. 2 a    at various stages of material removal from a three-layer lamination.  FIG. 3 a    illustrates the tool bit placed against the three layer lamination with no material removed.  FIG. 3 b    illustrates the lamination of  FIG. 3 a    with a portion of the first layer partially removed.  FIG. 3 c    illustrates the lamination of  FIG. 3 a    with a portion of the first layer removed. 
           [0015]      FIGS. 4 a -4 c    are illustrations showing the tool bit of  FIG. 2  at various stages of material removal in a  5 -layer lamination.  FIG. 4 a    show the lamination with a portion of the first layer removed.  FIG. 4 b    show the lamination with a portion of the first, second and third layers removed.  FIG. 4 c    shows lamination of  FIG. 4 b    with the tool bit withdrawn exposing the desired target layer. 
           [0016]      FIGS. 5 a -5 b    are illustrations showing another embodiment of a rotary tool bit configured according to the invention.  FIG. 5 a    shows an illustration of a rotary tool bit which comprises two mutually insulated electrically conductive cutters.  FIG. 5 b    shows an illustration of the tool bit of  FIG. 5 a    where the head is shown in partial section. 
           [0017]      FIGS. 6 a -6 b    are illustrations showing an embodiment of a layer removal tool kit configured according to the invention.  FIG. 6 a    shows the tool bit engaged in a clamp/guide mechanism.  FIG. 6 b    shows the tool bit retracted from the clamp/guide mechanism. 
           [0018]      FIG. 7 a    is an illustration showing yet another embodiment of a layer removal tool bit configured according to the invention comprising a tool face sensor pin and a remote contact. 
           [0019]      FIG. 7 b    is an illustration showing still another embodiment of a layer removal tool bit configured according to the invention comprising a conductive tool bit and a remote contact. 
           [0020]      FIG. 8  is an illustration showing an embodiment of a material removal system configured according to the invention comprising a clamp/guide mechanism, a rotary tool bit and a power tool for driving and controlling the tool bit. 
           [0021]      FIGS. 9 a -9 c    are illustrations showing still another embodiment of a material removal kit configured according to the invention comprising a clamp/guide mechanism and a rotary tool bit.  FIG. 9 a    illustrates a partial cross-section side-view of a kit with a tool bit and clamp/guide mechanism.  FIG. 9 b    illustrates the kit in  FIG. 9 a    with a tool bit engaged in the clamp/guide mechanism and a portion of a layer of the laminate removed by the tool bit.  FIG. 9 c    shows a top-view of the kit of  FIG. 9   b.    
           [0022]      FIG. 10  is an illustration showing an embodiment of a flat cable configured according to an aspect of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture and use of the apparatus and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings and described herein. Those of ordinary skill in the art will understand that the apparatus, methods and examples described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments and that the features may be used individually, singularly and/or in various combinations. Such modifications and variations are intended to be included within the scope of the present invention. 
         [0024]      FIG. 1 a    illustrates a perspective view of a prior art flat cable  1  with three mutually insulated conductors  2 ,  3  and  4  and an insulating material  5 .  FIG. 1 b    shows the sectional end view of the cable in  FIG. 1 a   . Certain regions of the cable comprise three layer laminations of a conductor sandwiched between two insulating layers. In other regions of the cable, the lamination comprises only two layers. U.S. Pat. Nos. 3,168,617; 3,547,718; 4,219,928; 4,695,679; 4,698,457; 4,864,081; 5,250,127; 5,274,195; 6,276,502; 6,492,595; and 8,237,051, which describe various flat cables, are incorporated herein by reference in their entirety. 
         [0025]      FIG. 2 a    illustrates a layer removal or stripping rotary tool bit  10  comprising head  11 , abrasive face  12  and mutually insulated tool face contact sensor pin  13  and tool face contact sensor pin  14 . The head  11  is preferably made of insulating material or materials, although conductive materials may be used so long as the tool face contact sensor pins are electrically mutually insulated. Shank  15  is attached to head  11 . Tool face contact sensor pins  13  and  14  retract into head  11  when the bit is placed against a flat surface, but maintain electrical contact with the surface. Conductor  16  electrically conductively connects tool face contact sensor pin  13  with ring  18 . Conductor  17  electrically conductively connects tool face contact sensor pin  14  with ring  19 .  FIG. 2 b    is an illustration showing the bottom view of rotary tool bit  10  and abrasive face  12  and the tips of tool face contact sensor pins  13  and  14 . 
         [0026]      FIG. 2 c    shows a partial cross section of the rotary tool bit  10  shown in  FIG. 2 a    and  FIG. 2 b   .  FIG. 2 d    shows an enlarged view of the sectioned portion of  FIG. 2 c   . Tool face contact sensor pin  13  comprises contact sensor pin body  13   a  and contact sensor pin neck  13   b  with intervening annular shoulder  13   c . Similarly, tool face contact sensor pin  14  is configured with contact sensor pin body  14   a  and contact sensor pin neck  14   b  with intervening annular shoulder  14   c . The tool face contact sensor pins are mutually insulated and are preferably manufactured from conductive materials and are more preferably manufactured from metals. Head  11  is preferably manufactured from insulating materials. Contact sensor pin bodies  13   a  and  14   a  are retractably received in bore  20   a  and bore  21   a  respectively, while contact sensor pin necks  13   b  and  14   b , are respectively received in bore  20   b  and bore  21   b . Electrically conductive spring  13   d  is disposed in bore  20   a  between the end of contact sensor pin body  13   a  and stop  20   c  to bias the pin to its fully extended position. Electrically conductive spring  14   d  is disposed in bore  21   a  between the end of contact sensor pin body  14   a  and stop  21   c  to bias the pin to its fully extended position. In their fully extended positions, the annular shoulders  13   c  and  14   c  rest against the intervening annular shoulders  20   d  and  21   d  between the larger and smaller diameter bores. Alternatively, tool bit  10  and head  11  may be manufactured from conductive materials so long as the tool face contact pins are insulated from each other and from the tool bit. 
         [0027]      FIGS. 3 a -3 b    illustrate the use of a rotary tool bit for the removal of a segment of a layer of laminate  31 . The tool bit and laminate are shown in partial section and section respectively. In  FIG. 3 a   , the tool bit is placed against the three layer lamination and tool face contact sensor pins  13  and  14  come in contact with surface of layer  34 .  FIG. 3 b    shows that layer  34  has been partially removed.  FIG. 3 c    shows that the tool bit has removed all of the intervening segment of layer  34  that is located between the tool face and targeted layer  35 . Tool face contact sensor pins are in direct electrical contact with layer  35 . By monitoring the resistance between screw terminals  20   d  and  21   d , the point at which the tool bit penetrates through layer  34  and comes into electrical contact with target layer  35  can be determined if the conductivity of layers  34  and  35  are different from each other. For example, if laminate  31  is comprised of copper targeted layer  35  and insulating layer  34 , the precise point at which the tool bit has removed the intervening segment of the insulation between the tool and the copper layer can be determined by monitoring the resistance between screw terminals  20   d  and  21   d.    
         [0028]      FIGS. 4 a -4 c    show illustrations of the tool bit  10  of  FIG. 2  being used to remove multiple layers of laminate  40 . The tool bit and laminate are shown in partial section and section respectively.  FIG. 4 a    shows that tool bit  10  has penetrated layer  41  and that tool face contact sensor pins  13  and  14  are in physical contact with a surface of layer  42 .  FIG. 4 b    shows that the tool face has penetrated layers  41 ,  42  and  43  such that tool face contact sensor pins  13  and  14  are in electrical contact with a surface of target layer  44 .  FIG. 4 c    shows that the tool bit  10  has been withdrawn exposing surface  44   a  of target layer  44 . The tool face contact sensor pins  13  and  14  are in their fully extended positions. It is preferred that the difference in conductivity between the target layer and at least the last layer to be removed is large. For example, it is preferred that the difference be comparable to what is typically considered to be the difference in conductivity of a conductor of electricity and an insulator. However, such a larger difference is not necessary and even minor differences in conductivity are sufficient. 
         [0029]      FIG. 5 a    shows an illustration of a rotary tool bit  50  with tool bit head  51  which comprises two mutually insulated electrically conductive cutters  52   a  and  52   b . Conductor  53   a  electrically connects cutter  52   a  with ring  54   a . Conductor  53   b  electrically connects cutter  52   b  with ring  54   b . It is preferred that conductors  53   a  and  53   b  be insulated wires.  FIG. 5 b    shows an illustration of the tool bit of  FIG. 5 a    where the head is shown in partial section. By rotating tool bit  50  about its longitudinal axis, cutters will make a cylindrical cut in layer  55 , eventually contacting surface or targeted layer  56 . If layers  55  and  56  have different conductivities, the point when the cutters contact target layer  56  can be determined by monitoring the resistance between ring  54   a  and  54   b.    
         [0030]      FIG. 6 a    illustrates kit  60  comprising the tool bit  61  (also shown in  FIG. 2 ) and clamp/guide mechanism  62  configured to securely hold laminate  63  and to properly position the tool bit relative to the laminate. The laminate and the clamp/guide mechanism are shown in section. Screws  64   a  and  64   b  are configured to securely clamp the two pieces  62   a  and  62   b  of the clamping/guide mechanism to each other. Other attachment devices, such as for example, quick disconnect clamps or C-clamps may be used in place of or in addition to the screws.  FIG. 6 b    illustrates the elements of the layer removal bit shown in  FIG. 6 a    where the tool bit has been withdrawn from the clamp/guide mechanism. Opening  65  and bore  65   a  are configured to rotatably receive tool bit  61 . It is preferred that the bore  65   a  of opening  65  have a diameter that is between 0.001 and 0.003 inches greater than the diameter of the cylindrical portion of the head of the tool bit  61 . 
         [0031]      FIG. 7 a    illustrates a kit  70  comprising a rotary tool bit  71  comprising an abrasive face  71   a  and barbed clamp  72  attached to laminate  73 . Tool bit head  71   b  and laminate are shown in section. Barbed clamp  72  is used to make electrical contact with targeted layer  73   a  of laminate  73  at a point that is at a convenient distance from the tool bit  71 . 
         [0032]    Tool bit  71  comprises at least one tool face contact sensor pin  71   b  configured to make electrical contact with the laminate  73 . Layer  73   b  is an insulating layer, while layer  73   a  has a conductivity that is higher than the conductivity of layer  73   b . By monitoring the resistance between electrical terminals  71   c  and  72   a , it can be determined when contact sensor pin  71   b  comes into electrical contact with layer  73   a . It is preferred that the conductivity of layer  73   a  be substantially different than the conductivity of layer  73   b.    
         [0033]      FIG. 7 b    shows another tool kit comprising tool bit  75  with head  76  and shank  76   b . Head  76  and shank  76   b  are manufactured of a conductive material, preferably of highly conductive material such as, for example steel or brass. The resistance between the tool bit head and barbed jaw clip  77  is monitored. Electrical contact  79  makes continuous contact with conductive shank  75 . For example, if layer  78   a  and layer  78   b  are insulating and layer  78   c  is conductive, the resistance between the terminal bit  79   a  and terminal  77   a  will change from a higher value to a lower value when the face of the tool bit  75  comes into contact with a surface of conductive layer  78   c.    
         [0034]      FIG. 8  illustrates layer removal system  80  which comprises tool bit  10  (also shown in  FIG. 2 a   ), a three opening clamp/guide mechanism  81  and a handheld, cordless power tool  82 . 
         [0035]    Power tool  82  comprises a drive section  83  configured to receive and grip shank of tool bit  10 . Brush  83   a  is electrically conductively connected to tool face contact sensor pin  13  by means of conductor  16  and ring  18 . Brush  83   b  is electrically conductively connected to tool face contact sensor pin  14  by means of conductor  17  and ring  19 . The resistance between brushes  83   a  and  83   b  is monitored by the system during the material removal process. This resistance is substantially determined by the conductivity of the material that bridges the gap between tool face contact sensor pin  13  and tool face contact sensor pin  14 . If the material is insulating, the overall resistance will be high. If the material is conductive, for example, if the gap is bridged by a metal surface, the overall resistance will be low. The operation of the tool bit  10  may be controlled by the system based on the measured resistance between brushes  83   a  and  83   b . It is preferred that power tool  82  further comprise an automatic clutch mechanism or other device to automatically stop or curtail the rotation of bit  10 . The devices for automatically stopping or curtailing the rotation of the bit are controlled based on the resistance detected between tool face contact sensor pins  13  and  14 . 
         [0036]    Clamping mechanism  81  has a lower support plate  81   a  and guide plate  81   b  comprising three opening  82   a ,  82   b  and  82   c  which are configured to rotatably receive head  11  of bit  10 . Laminates may be clamped between support plate  81   a  and guide plate  81   b . Bit  10  may then be placed in, for example, opening  82   a  and rotated about its longitudinal axis by power tool  82 . When the resistance measured between the brushes is within a certain predetermined range, the power tool automatically stops or slows the rotation of the tool bit. One or more layers of a laminate may be removed by this procedure. 
         [0037]      FIG. 9 a    illustrates kit  90  which comprises tool bit  91  and clamp/guide mechanism  92 . Tool bit  91  comprises conductive head  93  with abrasive face  93   a . Alternatively, the face of the tool bit head may have cutting blades such as an end-mill or a Forstner bit. If a Forstner bit is used, it is preferred that the centering brad be eliminated. U.S. Pat. Nos. 5,695,304 and 6,354,774, which describe various Forstner bits, are incorporated herein by reference in their entirety. A conventional power tool, such as an electrical hand drill or drill press (not shown), may be used to drive the tool bit  91 . 
         [0038]    Laminate  94  comprises insulating layers  94   a  and  94   b  and conductive layer  94   c . Upper clamp/guide mechanism  95   a  comprises spike  96 , electrical contact  97 , and indicator light  98 . The indicator light is illuminated when the electrical resistance between spike  96  and contact  97  comes within a predetermined range. Alternatively, the light may be illuminated when the spikes  96  and tool bit  91  come into electrical contact with the same metal layer. The lower clamp/guide mechanism  95   b  comprises cavity  96   b  that is configured to receive spike  96  and any displaced or severed pieces of laminate  94 . 
         [0039]      FIG. 9 b    illustrates kit  90 , where the tool bit  91  has penetrated through insulating layer  94   a  and contacted the upper surface of targeted conductive layer  94   c . Spike  96  has also penetrated the nonconductive layer  94   b  and come into electrical contact with conductive layer  94   c . Electrical contact  97  makes electrical contact with the cylindrical section of head  93 . The head  93  is conductive and when it electrically contacts the exposed surface of targeted layer  94   c  it completes the circuit between spike  96  and contact  97  and causes indicator light  98  to be illuminated.  FIG. 9 c    illustrates a top view of upper clamp/guide mechanism  95   a  shown in  FIGS. 9 a  and 9 b   . Electrical contact  97  is electrically connected to cylindrical surface  93   b  of tool bit  10 .  FIG. 9 c    shows a top view of indicator light  98 , laminate  94 , and clamping screws  99   a ,  99   b ,  99   c  and  99   d.    
         [0040]      FIG. 10  illustrates a laminate  100  with conductors  100   a ,  100   b , and  100   c . The laminate is marked with positioning lines  101   a  and  101   b  and positioning circles  102   a ,  102   b  and  102   c  and  103   a ,  103   b  and  103   c . The positioning lines and circles are preferably marked on the surface of laminate  100  at desired regular intervals. Markings may be dashed or solid lines of any convenient color. The lines may be used to properly locate clamp/guide mechanisms relative to the laminate. 
         [0041]    The invention has been described in terms of functional principles and illustrations of specific embodiments. Embodiments described herein, including descriptions of the figures, are merely intended as exemplary, but the concept of the invention is not limited to these embodiments. The following claims are not limited to or by the described illustrative embodiments, figures, and stated objectives of the invention or the abstract. Furthermore, various presently unforeseen or unanticipated combinations of the disclosed embodiments, or their elements, or alternatives, variations or improvements which may become apparent to those of skill in the art are also intended to be encompassed by the following claims.