Patent Publication Number: US-6659140-B2

Title: Apparatus and method for cutting braid of shielded wire

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus and method for effectively automatically cutting a braid of a shielded wire having a relatively large diameter for use in an electric vehicle and others. 
     2. Description of the Related Art 
     Traditionally, a shielded wire was processed manually in all the steps. 
     Specifically, the sheath of the tip of a shielded wire cut into segments of a prescribed length is stripped using a tabletop tool so that the braid of conductive metal is exposed. The braid is cut into segments each having a prescribed length. With a shield contact of conductive metal manually inserted into the shielded wire, the braid is folded back toward the contact using a center punching. With a shield pipe of conductive metal manually inserted in the shielded wire and braid sandwiched between and kept in contact with the shield contact and the shield pipe, the shield pipe is squeezed using a squeezing machine. Further, the inner face at the tip of the shielded wire is stripped using the tabletop tool so that a terminal is connected to a core wire by a crimping machine (The shape and other details of the shield contact and shield pipe can be seen from FIG.  3 ). 
     The shielded wire is used in such a mode that a connecting flange is combined with the shield pipe and earth-connected to a vehicle body along the outer surface of the housing of resin. The terminal of the shielded wire is connected to a motor, inverter or battery of an electric vehicle. 
     However, in the above conventional means for cutting the braid of the shielded wire, the braid was manually cut using snips. Therefore, the length of each of the segments of the cut braid is uneven. The tip of cut braid is liable to be irregular. The quality is not stable, and a large number of man-hours is required. This presents a problem of increasing the production cost. 
     SUMMARY OF THE INVENTION 
     In view of the above problem, a first object of this invention is to provide an apparatus which can cut the braid of a shielded wire into precise lengths cleanly with no irregularity and effectively with a small number of man-hours. 
     A second object of this invention is to provide a method for cutting the braid of a shielded wire into precise lengths cleanly with no irregularity and effectively with a small number of man-hours. 
     In order to attain the above first object, in accordance with this invention, there is provided a braid cutting apparatus for a shielded wire comprising: a die located outside an exposed braid of the shielded wire; means for opening the braid; a punch which is to advance inside the braid; and a guide member for guiding the braid in a direction to open further and an inner sheath of the shielded wire inside the braid to an inside of the punch. 
     In this configuration, the exposed braid of the shielded wire is inserted into the inside of die, the braid is opened outwardly in taper by a braid opening means, the inner sheath of the shielded wire is inserted in the inside of the punch and the braid is further opened in taper outwardly by a guide member. For this reason, the tip of the punch is inserted surely and smoothly inside the braid, i.e. between the braid and the inner sheath of the shielded wire so that the braid can be surely sheared between the punch and the die. 
     In the above apparatus, preferably, the opening means comprises: a pair of opening pallets which are freely reclosable, a pair of sliding members with the pair of opening pallets fixed; a link for moving the pair of sliding members in opposite directions; and driving means for swinging the link. 
     In this configuration, the link is swung by the driving means so that the pair of sliders are opened or closed simultaneously with the opening pallets. Therefore, the braid of the shielded wire is pressed repeatedly by the opening pallets under appropriate force. Accordingly, the braid can be surely opened in a trumpet without being injured. 
     In the apparatus described above, preferably, the guide member is made dividable, and when the punch advances, the guide member is opened outwardly by the driving means and a moving means to retreat. 
     In this configuration, since the guide member opens and retreats, when it is opens, the braid is opened further outwardly. For this reason, the punch is inserted more surely inside the braid. 
     In order to attain the second object, there is provided a method of cutting a braid of a shielded wire comprising the steps of: opening an exposed braid of the shielded wire, further opening the braid along an outer slope of a guide member while guiding an inner sheath of the shielded wire inside the braid to an inside of a circular punch, and shearing the braid into a required length between the punch and a die located outside the braid while advancing the punch inside the braid. 
     In this configuration, the braid opened primarily opened by the opening means is guided along the outer slope of the guide member so that it is further (secondarily) opened greatly outwardly. The inner sheath of the shielded wire is smoothly inserted into the guide member, i.e. inside the punch along the inner slope of the guide member. 
     In the method described above, preferably, after the braid is opened along an outer slope of the guide member, the guide member is opened outwardly. 
     In this configuration, since the braid is opened further outwardly when the guide member is opened, the punch is inserted more surely inside the braid. Thus, the tip of the punch and that of the braid do not interfere with each other so that the braid does not bend inwardly. This prevents poor cutting of the braid. 
     The above and other objects and features of this invention will be more apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic perspective view of an embodiment of a shielded wire machining device inclusive of a braid cutting device of a shielded wire according to this invention; 
     FIGS. 2A to  2 J are plan views showing the machining method of the shielded wire; 
     FIG. 3 is an exploded perspective view showing the state on the way of machining the shielded wire; 
     FIG. 4 is a side view of an embodiment of the braid cutting device for a shielded wire according to this invention; 
     FIG. 5 is a front view showing the braid turn-over means of the braid cutting device; 
     FIG. 6 is a sectional view of the main part of the braid cutting means in FIG. 8; 
     FIG. 7 is a view for explaining the state of cutting the braid; and 
     FIG. 8 is a view showing the function of a guide member. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now referring to the drawings, an explanation will be given of an embodiment of this invention. 
     FIG. 1 schematically shows an embodiment of a shielded wire processing device including a device for cutting the braid of a shielded wire according to this invention. 
     A shielded wire processing apparatus, generally  1  includes individual devices arranged successively from the right side, i.e., an operation console  2  for performing a change in a product number, switching between a manual operation and an automatic operation, etc., a wire setting device  3 , a shield contact fitting device  4 , a sheath incision device  5 , a sheath extracting device  6 , a braid cutting device  7 , a braid fold-back device  8 , shield pipe inserting device  9  ( 8  and  9  are illustrated as a single device for brevity of illustration), sheath pipe squeezing device  10 , a peeling device  11 , a terminal squeezing device  12 , a product drawing device  13 , and a conveying device  14  for moving a shielded wire  15  along the respective devices  3  to  13 . These devices  3  to  13  are arranged in parallel at substantially regular intervals. 
     In FIG. 1, reference numeral  16  denotes a hopper for supplying a shield contact, and reference numeral  17  denotes a hopper for supplying a shield pipe. The shielded wires  15  each may a thick wire having a sectional area of about 15 mm 2 . The shielded wires  15  folded back in a U-shape or not folded back are set one by one in parallel in the wire setting device  3  at the right end of the conveying device  14 . 
     Now referring to FIGS. 1 and 2, an explanation will be given of a shielded wire processing method using the shielded wire processing device  1 , and its operation. 
     First, as seen from FIG. 2A, the shielded wire  15  cut into a segment having a prescribed length is set in the shield setting device  3  by an operator. The only operation performed by the operator is to set the wire. When the shielded wire  15  is set, the wire conveying device  14  is shifted by one pitch leftward to convey the shielded wire  15  to the adjacent shield contact inserting device  4 . 
     As seen from FIG. 2B, a ring-shaped shield contact  19  of conductive metal is fit over the shielded wire  15  by the shield contact fitting device  4 . As also seen from FIG. 3, the shield contact  19  is composed of a large-diameter segment  19   a  and a small-diameter segment  19   b  which are stepped. The shielded wire  15  inserted into the shield contact  19  is conveyed to the sheath incision device  5  by the conveyer device  14 . As seen from FIG. 2C, a circular incision  21  is made on the insulating sheath (outer sheath)  20  of the shielded wire  15  at a prescribed position located nearer to the tip of the wire than the shield contact  19 . 
     The shielded wire  15  is conveyed to the sheath drawing device  6 . As seen from FIG. 2D, the sheath  20  is drawn out so that an internal metallic braid  22  is exposed over a prescribed length. It is needless to say that the braid  22  is composed of slender metallic wires which are knitted in a crossing manner as seen from FIG.  3 . The shielded wire is conveyed to the braid cutting device  7 . As seen from FIG. 2E, the exposed braid  22  is cut into a prescribed length so that an insulating inner sheath  24  is exposed. 
     The shielded wire  15  is conveyed to the braid fold-back device  8 . As seen from FIG. 2F, the braid  22  is folded back toward the small-diameter portion  19   b  of the shield contact  19 . Further, a ring-shaped shield pipe  23  of conductive metal is inserted the from the tip side of the shielded wire  15  so that the braid  22  (not shown) is sandwiched between and brought in contact with the outer surface of the small diameter portion  19   b  of the shield contact  19  and the inner surface of the shield pipe  23 . The angle of fold-back of the braid  22  ranges from 90° to 180°. 
     The shielded wire  15  is conveyed to the shield pipe squeezing device  10 . As seen from FIG. 2H, the shield pipe  23  is squeezed in a hexagon so that it is fixed to the shield contact  19 . Since the braid  23  is sandwiched between the shield contact  19  and the shield pipe  23 , the shield contact  19  and the shield pipe  23  are firmly fixed to the shielded wire  15 . 
     The shielded wire  15  is conveyed to the peeling device  11 . As seen from FIG. 2I, the tip side of the inner sheath  24  is peeled over a prescribed length so that a core (conductor) is exposed. Further, the shielded wire  15  is conveyed to the terminal squeezing device  12 . As seen from FIG. 2J, a terminal  26  is crimped on the exposed core  25 . Finally, the product  27  of the shielded wire is taken from the shielded wire processing device  1  into an external pallet (not shown) with the aid of the product drawing device  13 . 
     Incidentally, the terminal squeezing device  12  may be provided separately from the shielded wire processing device  1 . 
     Now referring to FIGS. 4 to  8 , an explanation will be given of an embodiment of a device for cutting the braid of a shielded wire and the braid cutting method according to this invention. 
     In FIG. 4, reference numeral  107  denotes a ring-shaped die for cutting a braid;  109  a ring-shaped guide member;  110  a ring-shaped braid opening pallet;  111  an air-actuated or hydraulic horizontal cylinder for primarily advancing a punch  108 ; and  112  a large-sized and strong air-actuated or hydraulic cylinder for secondarily advancing the punch  108  and cutting the braid  22  of the shielded wire  15  between the die  107  and the punch  108 . Reference numerals  113  and  114  (FIG. 5) denote air cylinders (driving means) for laterally opening/closing the ring-shaped braid opening pallet  110 , respectively. 
     The shielded wire  15  is caught by a chuck  115  in its intermediate portion in the longitudinal direction. The shielded wire  15  is also supported by a supporting chuck (supporting member)  116  in its tip side so that it is movable in the longitudinal direction. The chuck  115  includes a pair of left and right catching pallets. The chuck  115  is opened/closed by the air chuck cylinder  105 . The wire chuck in the conveyer device  14  (FIG. 1) has the same structure. 
     The supporting chuck  116  includes a pair of left and right symmetrical closable pallets which do not catch the shielded wire  15 , but horizontally supports it in light contact therewith. The die  107  is located ahead of the supporting chuck  116 . A frame  117  to which the die  107  is fixed and the supporting chuck  116  are integrally fixed to a horizontal base plate  118 . The base plate  118  is adapted to be slidable in the longitudinal direction of the wire along a guide rail  119 . 
     The base plate  118  is driven back and forth by a ball screw shaft (not shown). A primary cylinder  111  with a small diameter for moving a punch is attached to the frame  120  extended upright at the rear of the base plate  118 . A secondary cylinder  112  with a large diameter is adapted to be movable back and forth relative to a frame  120  by a guiding means  121  such as a guide rail. A horizontal air cylinder (moving means)  122  with a small diameter for moving the guide member back and forth is attached to the secondary cylinder  112 . The guide member  109  in a chuck-system is coupled with an opening/closing cylinder  123  which is in turn coupled with a rod  124  of the moving cylinder  122 . 
     As seen from FIG. 5, a braid opening means  125  has a pair of left and right braid opening pallets  110  which are attached to sliding plates (sliding member)  126  and  127  which are movable in opposite directions. Each of the sliding plates  126 ,  127  are engaged with a single substantially vertical link  128  at upper and lower shaft positions. The upper end and lower end of the link  128  are coupled with the rods  129  and  130  of the cylinders  113  and  114 , respectively. The stem of each of the cylinders  113  and  114  is rotatably supported. Each of the sliding plates  126  and  127  is adapted to be movable in a horizontal direction (radial direction of the wire) within a gap between a hole portion and a shaft portion. 
     FIG. 6 is an enlarged view of the cutting means such as the die  107  and punch  108  in FIG.  4 . The die  107  is formed in a circular shape. The punch  108  is movable into an inner diameter portion  107   a  of the die  107 . The inner diameter portion  107   a  is constituted by a horizontal narrow segment with a uniform inner diameter. This portion is successive to a front vertical plane  107   b  and a rear tapered plane  107   c . The edge at the front end of the inner diameter portion  107   a  serves as a shearing blade. The outer periphery of the die is stepped and the stepped portion is engaged with an outer front half frame  117   a  so that it is not movable forward. 
     The braid opening pallets  110  are kept in intimate contact with the front end of the die  107  so as to be slidable in the radial direction. A rear half frame  117   b  is kept in contact with the rear end of the die  107 . The tapered plane  107   c  is smoothly successive to the tapered plane  117   c.  Each of the tapered planes  117   c  and  107   c  serves as a guide plane for guiding the tip of the braid  22  of the shielded wire (FIG.  4 ). 
     The punch  108  is cylindrically shaped, and composed of a thin segment  108   a  with a small diameter on the tip side and a thick segment  108   b  with a large diameter backward successive thereto. The inner diameter of the thin segment  108   a  is equal to that of the thick segment  108   b.  The outer diameter of the thin segment  108   a  is smaller than that of the thick segment  108   b.  The outer edge  108   c  at the tip of the thin segment  108   a  serves as a shearing blade. 
     The thin segment  108   a  advances into the inner diameter portion  109   c  of the guide member  109  with a slight gap therefrom. The guide member  109  is formed in a circular shape divided into two left and right segments. The guide member  109  has an inner slope  109   a  for wire guiding, which covers the tip of the thin segment  108   a  of the punch  108 , and an outer slope  109   b  for braid guiding. 
     The inner slope  109   a  is formed is a short length whereas the outer slope  109   b  is formed in a relatively long length extended backward. The inner slope  109   a  is successive to a circular vertical plane  109   d  with which the tip of the thin segment  108   a  of the punch  108  is in contact. The minimum inner diameter of the guide member  109  is equal to the inner diameter of the thin segment  108   a  of the punch  108 . Both slopes  109   a  and  109   b  cross to form an acute angle. The tip of the guide member  109  is formed in a wedge shape in section. The guide member  109  is provided integrally to or separately from a pair of left and right arms  104  which can be opened/closed freely. Specifically, the one semi-circular guide member  109  and the other semi-circular guide member  109  are attached to the one arm  104  and the other arm  104 , respectively. 
     The pair of left and right guide members  109  are opened/closed by an opening/closing cylinder  123  (FIG.  4 ). In opening the guide members, the punch  108  advances toward the die  107 . The braid opening pallet  110  has a slightly acute circular tip, whose degree is less than a cutter. In the description of the specification, the “front” of the shielded wire  15  is coincident to the “front” of the die  107 . In contrast, the “front” of the punch  108  is opposite to the “front” of the guide member  109 . 
     In FIG. 4, the horizontal base plate  118  is advanced slidably by a ball screwing shaft and servo motor so that the tip of the shielded wire  15  (exposed portion of the braid  22 ) is inserted into the die  107 . In this state, a pair of upper and lower cylinders  113  and  114  are operated several times in opposite directions, respectively. Thus, a link  128  swings so that the braid opening pallets  110  repeatedly open/close integrally to the pair of left and right slide plates  126  and  127 . As shown in FIG. 7, the pallets  110  press the braid  22  of the shielded wire  15  against the inner sheath  24  several times (four to five times) so that the braid  22  is gradually expanded in diameter outwardly. Accordingly, the circular punch  108  can be inserted comparatively easily between the braid  22  of the wire  15  and inner sheath  24 . 
     In the state where the braid  22  has been expanded, the secondary cylinder  112 , punch  108  and guide member  109  are advanced by the operation of extending the primary cylinder  111  as shown in FIG.  4 . Then, as shown in FIG. 8, the inner sheath  24  of the shielded wire  15  is initially (slightly) inserted into the inner diameter portion (inner space) of the punch  108 . Simultaneously, the opened portion of the braid  22  slides along the outer slope  109   b  of the guide member  109  so that it is further opened. Since the guide member  109  is opened left and right, the braid  22  is extended more outwardly. In this state, the guide member  109  is moved backward. 
     The operation of the guide member  109  of opening the braid further facilitates the insertion of the punch  108 . When the shielded wire  15  is inserted, the tip of the punch  108  is completely housed in the inner diameter portion  109   c  of the guide member  109  so that interference between the tip of the inner sheath of the shielded wire  15  and that of the tip of the punch  108  is prevented. Thus, the wire can be smoothly inserted. 
     The guide member  109  is opened outwardly, and moved backward by the compressing operation of the horizontal air cylinder  122  as shown in FIG. 4 so that the secondary cylinder  112  is extended. Then, the punch  108  is inserted into the opened portion of the braid  22  as shown in FIG.  7 . At this time, the braid  22  is sandwiched between the outer periphery of the punch  108  and the inner periphery of the die  7  and sheared or cut instantaneously. This is performed to exclude the redundant segment at the tip of the braid  22  and define the protruding length of the braid  22  of the outer sheath  20 . 
     The main part of the cutting device inclusive of the punch  108  and die  107  moves backward along a guide rail  119  by the function of the servo motor and ball screw shaft (not shown) so that the shielded wire  105  is extracted from the die  107 . In this state, when the braid opening pallets  110  are operated several times in its empty state, owing to its vibration, the refuse of the braid is thrown into a waste box. 
     By moving forward or backward the main part of the cutting device using the servo motor and ball screw shaft, the cutting length of the braid  22  can be adjusted freely so as to correspond to the shielded wires  15  of the several product numbers. In this case, the braid  22  is turned over so that the inner sheath  24  is located on the inner wall of the punch  108 . In this state, the braid  22  is cut by the outside of the punch  108  so that only the braid  22  can be surely cut without injuring the inner sheath  24  and the core  25 . 
     The shielded wire  15  with the braid  22  thus partially cut is sent to the adjacent braid fold-back device  8  by the conveying device  14  (FIG.  1 ).