Abstract:
A cap that covers an electric wire connecting portion in which respective conductive portions of a plurality of electric wires are interconnected is molded in such a manner that one end side of a tube having a tubular shape is hermetically sealed by welding treatment, and a tongue portion is formed by a stamping process on the other end side.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a cap that covers an electric wire connecting portion in which respective conductive portions of a plurality of electric wires are interconnected, and relates to a manufacturing method of the cap. 
         [0003]    2. Description of the Related Art 
         [0004]    For example, in cabling of a wire harness, insulating outer sheaths of a plurality of electric wires are stripped, and exposed conductive portions are interconnected, whereby an electric wire connecting portion is formed. Moreover, a cap made of an insulating material is used in order to ensure insulating property, waterproof and the like of a spot of the electric wire connecting portion. 
         [0005]    As this type of the conventional cap, one shown in  FIGS. 1A and 1B  and one shown in  FIGS. 2A and 2B  are disclosed in Japanese Patent Laid-Open Publication No. H11-178142 (published-in 1999). The cap  100  shown in  FIGS. 1A and 1B  is one formed by injection molding using a metal mold. The cap  100  is composed of: a cylinder  101  in which one end is closed; and a tongue portion  102  protruded from the other end of the cylinder  101 . 
         [0006]    In work to cover an electric wire connecting portion  105  of a plurality of electric wires W by using the cap  100 , first, as shown in  FIG. 1A , the electric wire connecting portion  105  of the plurality of wires W is inserted into the cylinder  101  of the cap  100 . Next, as shown in  FIG. 1B , the tongue portion  102  of the cap  100  is bound with the plurality of electric wires W by a tape  106 , and this is the end of the work. 
         [0007]    The cap  110  shown in  FIGS. 2A and 2B  is composed of: a heat-shrinkable tube  111  formed by extrusion molding, in which both ends are opened; and a hot melt layer  112  adhered onto an inner surface of the heat-shrinkable tube  111 . 
         [0008]    In work to cover the electric wire connecting portion  105  of the plurality of wires W by using the cap  100 , first, as shown in  FIG. 2A , the electric wire connecting portion  105  of the plurality of electric wires W is inserted into the heat-shrinkable tube  111 . Next, as shown in  FIG. 2B , the cap  110  is heated by a hot wind and the like. Then, the heat-shrinkable tube  111  shrinks by being heated, and in addition, the hot melt layer  112  is solidified by a temperature drop caused after such heating, and this is the end of the work. 
       SUMMARY OF THE INVENTION 
       [0009]    The conventional cap  100  shown in  FIGS. 1A and 1B  has a problem that, since the cap  100  is formed by the injection molding using the metal mold, forming process cost thereof is high, resulting in that cost of the parts is high. 
         [0010]    In the conventional cap  110  shown in  FIGS. 2A and 2B , since the heat-shrinkable tube  111  is formed by the extrusion molding, forming process cost thereof is low. However, the cap  110  has a problem that the work to cover the electric wire connecting portion  105  is cumbersome since it is necessary to form the hot melt layer  112  on the inner surface of the hot-shrinkable tube  111 , and to implement such heating treatment for the cap  110  concerned by the hot wind and the like. 
         [0011]    The present invention has been made in order to solve the above-described problems. It is an object of the present invention to provide a cap in which the cost of the parts is low, and in addition, the work to cover the electric wire connecting portion is simple, and to provide a manufacturing method of the cap. 
         [0012]    A first aspect of the present invention is a cap that covers an electric wire connecting portion in which respective conductive portions of a plurality of electric wires are interconnected, the cap comprising: a tube having a tubular shape; a first end hermetically sealed by welding treatment; and a second end on which a tongue portion is formed by a stamping process. 
         [0013]    In accordance with such a configuration as described above, the welding treatment and cutting/stamping processes are implemented for the tube formed by the extrusion molding, thus making it possible to fabricate the cap. Therefore, in comparison with the cap formed by the injection molding using the metal mold, good productivity is brought, and cost of equipment is saved. Moreover, the electric wire connecting portion is inserted into the cap, and the tongue portion is bound with the plurality of electric wires by a tape, whereby the work to cover the electric wire connecting portion by the cap is completed. From the above, the cost of the parts is low, and in addition, the work to cover the electric wire connecting portion is simple. 
         [0014]    In the above-described configuration, a configuration may be adopted, in which a plurality of the caps are fabricated from a long-length tube, the tongue portions of two caps fabricated adjacent to each other are set at positions opposed to each other along a longitudinal direction of the long-length tube, and both of the tongue portions set at the positions opposed to each other are formed by the stamping process. 
         [0015]    In accordance with such a configuration as described above, a loss of a material of the plurality of caps is saved when the caps are fabricated from the long-length tube, and this contributes to reduction of the cost. 
         [0016]    Moreover, in the above-described configuration, a configuration may be adopted, in which a protruded portion formed by the stamping process is provided on an end of the tongue portion. 
         [0017]    In accordance with such a configuration as described above, when external force to pull out the cap from the electric wires is applied to the cap, the protruded portion of the tongue portion increases frictional force with the electric wires, and accordingly, the cap is not detached easily. 
         [0018]    Moreover, in the above-described configuration, a configuration may be adopted, in which a protruded portion formed by heating treatment is provided on an end of the tongue portion. 
         [0019]    In accordance with such a configuration as described above, similar functions/effects to those of the above are obtained. 
         [0020]    Moreover, a second aspect of the present invention provides a method of manufacturing a cap, including: forming a hermetically sealed portion by implementing welding treatment for a long-length tube at a predetermined interval in a longitudinal direction thereof; cutting the long-length tube so that the hermetically sealed portion can be one end of the cap; and implementing a stamping process for the long-length tube in order to form a tongue portion on the other end side of the cut tube. 
         [0021]    In accordance with such a configuration as described above, the plurality of caps can be continuously fabricated from the long-length tube. Moreover, as a raw material of the cap, the tube formed by the extrusion molding can be used. Furthermore, the welding treatment and the stamping process are implemented for the tube, whereby each cap is fabricated. Accordingly, in comparison with the cap formed by the injection molding using the metal mold, good productivity is brought, and the cost of the equipment is saved. Moreover, the electric wire connecting portion is inserted into the cap, and the tongue portion is bound with the plurality of electric wires by the tape, whereby the work to cover the electric wire connecting portion by the cap is completed. From the above, the cap can be mass-produced, in which the cost of the parts is low, and in addition, the work to cover the electric wire connecting portion is simple. 
         [0022]    Moreover, in the above-described configuration, a configuration may be adopted, in which the tongue portions of two caps fabricated adjacent to each other from the long-length tube are set at positions opposed to each other along a longitudinal direction of the long-length tube, in the welding step, two spots of the long-length tube, the spots being close to each other, are welded simultaneously, and the hermetically sealed portions are formed in the two spots close to each other, and in the cutting/stamping process step, a spot between the hermetically sealed portions in the two spots close to each other is cut, and the two tongue portions set at the positions opposed to each other are stamped. 
         [0023]    In accordance with such a configuration as described above, the two caps can be fabricated simultaneously by the welding treatment and the cutting/stamping process, each of which is implemented once. Accordingly, this leads to further enhancement of the productivity. Moreover, the loss of the material of the plurality of caps is saved when the caps are fabricated from the long-length tube, and this contributes to the reduction of the cost. 
         [0024]    Moreover, in the above-described configuration, a configuration may be adopted, in which the tongue portions of two caps fabricated adjacent to each other from the long-length tube are set at positions opposed to each other along a longitudinal direction of the long-length tube, in the welding process, a predetermined spot of the long-length tube is welded to form the hermetically sealed portion, in the cutting process, a center portion of the hermetically sealed portion is cut, and in the stamping process, two tongue portions set at positions opposed to each other are stamped. 
         [0025]    In accordance with such a configuration as described above, similar functions/effects to those of the above are obtained. 
         [0026]    Moreover, in the above-described configuration, a configuration may be adopted, in which the welding treatment, the cutting process and stamping process are performed simultaneously. 
         [0027]    In accordance with such a configuration as described above, in addition to the above-described effects, further enhancement of the productivity is achieved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIGS. 1A and 1B  are front views explaining respective works to cover an electric wire connecting portion by using a cap in a conventional example. 
           [0029]      FIGS. 2A and 2B  are front views explaining respective works to cover the electric wire connecting portion by using the cap in another conventional example. 
           [0030]      FIGS. 3A and 3B  show a first embodiment of the present invention:  FIG. 3A  is a front view of a cap; and  FIG. 3B  is a cross-sectional view of  FIG. 3A , which is taken along a line  3 B- 3 B. 
           [0031]      FIGS. 4A and 4B  are front views explaining respective works to cover the electric wire connecting portion by using the cap, showing the first embodiment of the present invention. 
           [0032]      FIGS. 5A and 5B  show the first embodiment of the present invention:  FIG. 5A  is a schematic plan view of a cap manufacturing apparatus; and  FIG. 5B  is a schematic front view of the cap manufacturing apparatus. 
           [0033]      FIGS. 6A and 6B  show the first embodiment of the present invention:  FIG. 6A  is a plan view showing a spot of a long-length tube, which is subjected to welding treatment; and  FIG. 6B  is a cross-sectional view of  FIG. 6A , which is taken along a line  6 B- 6 B. 
           [0034]      FIGS. 7A and 7B  show another aspect of the first embodiment of the present invention:  FIG. 7A  is a plan view showing a spot of the long-length tube, which is subjected to the welding treatment; and  FIG. 7B  is a cross-sectional view of  FIG. 7A , which is taken along a line  7 B- 7 B. 
           [0035]      FIG. 8  is a plan view showing a spot of the long-length tube, which is subjected to a stamping process, showing the first embodiment of the present invention. 
           [0036]      FIG. 9  is a plan view of a cap according to a second embodiment of the present invention. 
           [0037]      FIG. 10  is a plan view of a cap according to a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    A description will be made below of embodiments of the present invention based on the drawings. 
         [0039]    As shown in  FIGS. 3A and 3B , a cap  1 A is formed of a tube  2 , in which one end side is made as a hermetically sealed portion  3  by welding treatment, and a tongue portion  4  is formed by a stamping process on the other end side. The tube  2  is one obtained by forming a material such as vinyl chloride, polypropylene (PP) and elastomer, which is capable of being subjected to extrusion molding, into a cylindrical shape by the extrusion molding. The cap  1 A is fabricated by using the tube  2  described above. A manufacturing method of the cap  1 A will be described below in detail. 
         [0040]    Next, a description will be made of work to cover an electric wire connecting portion  10  of a plurality of electric wires W by using the cap  1 A. As shown in  FIG. 4A , the electric wire connecting portion  10  of the plurality of electric wires W is inserted into the tube  2  from the other end side thereof. Then, as shown in  FIG. 4B , the tongue portion  4  of the cap  1 A is bound with the plurality of electric wires W by a tape  11 , and this is the end of the work. 
         [0041]    Next, a description will be made of a cap manufacturing apparatus  20 . As shown in  FIGS. 5A and 5B , the cap manufacturing apparatus  20  includes: first to third tube feeding units  22  to  24  arranged on a base  21  at an interval in a conveying direction B; a tube welding unit  25  disposed on the base  21  and immediately downstream of the first tube feeding unit  22 ; and a tube cutting/stamping unit  26  disposed on the base  21  and between the second and third tube feeding units  23  and  24 . 
         [0042]    The first to third tube feeding units  22  to  24  include a pair of feed rollers  22   a  and  22   b , a pair of feed rollers  23   a  and  23   b , and a pair of feed rollers  24   a  and  24   b , respectively, in each pair of which the rollers are arranged up and down. A long-length tube  30  is disposed between the pair of feed rollers  22   a  and  22   b , the pair of feed rollers  23   a  and  23   b , and the pair of feed rollers  24   a  and  24   b . The long-length tube  30  is conveyed at an interval of a predetermined pitch L by rotating the pairs of feed rollers  22   a  and  22   b ,  23   a  and  23   b , and  24   a  and  24   b . 
         [0043]    Here, a plurality of the caps  1 A are continuously fabricated from the long-length tube  30 , and the tongue portions  4  and  4  of two caps  1 A and  1 A fabricated continuously are set at positions opposed to each other along a longitudinal direction of the long-length tube  30 . In this case, the predetermined pitch L has a length required to fabricate these two caps  1 A and  1 A. 
         [0044]    The tube welding unit  25  includes an up and down pair of welders  25   a  and  25   b . Every time when the long-length tube  30  is fed at the predetermined pitch L by the first to third tube feeding units  22  and  24 , the tube welding unit  25  implements the welding treatment for the long-length tube  30  by the pair of welding units  25   a  and  25   b . By the welding treatment, as shown in  FIGS. 6A and 6B , the hermetically sealed portions  3  and  3  are formed on two spots of the long-length tube  30 , which are close to each other. As welding means, there are an ultrasonic wave, a hot wind, thermocompression bonding, and the like. 
         [0045]    The tube cutting/stamping unit  26  includes: a lower pedestal  26   a ; an upper stamper  26   b ; and a cutter  2   c . Every time when the long-length tube  30  is fed at the predetermined pitch L by the first to third tube feeding units  22  to  24 , the tube cutting/stamping unit  26  simultaneously performs stamping of the long-length tube  30  by the stamper  26   b  and cutting of the long-length tube  30  by the cutter  26   c . As shown in  FIG. 8 , the stamper  26   b  stamps the long-length tube  30  so as to form the two tongue portions  4  and  4  set at the positions opposed to each other. The cutter  26   c cuts the long-length tube  30  at a position between the two hermetically sealed portions  3  and  3  close to each other. 
         [0046]    Note that, in this embodiment shown in  FIGS. 5A and 5B  and  FIGS. 6A and 6B , a configuration is adopted, in which the two hermetically sealed portions  3  and  3  are formed by welding the two spots of the long-length tube  30 , which are close to each other, and the spot between the hermetically sealed portions  3  and  3  is cut. However, a configuration may also be adopted, in which, as shown in  FIGS. 7A and 7B , a large hermetically sealed portion  3  is formed on one spot of the long-length tube  30 , and a center portion M of the hermetically sealed portion  3  is cut, whereby the two tongue portions  4  and  4  are formed. 
         [0047]    Next, a description will be made of actions of the manufacturing apparatus  20 . After conveying the long-length tube  30  at the predetermined pitch L, the first to third tube feeding units  22  to  24  stop conveying the long-length tube  30 . When the conveying of the long-length tube  30  is stopped, the upper welder  25   a  of the tube welding unit  25  goes down until being attached with pressure onto the lower welder  25   b , and implements the welding treatment for the long-length tube  30 . By the welding treatment, as shown in  FIGS. 5A and 5B , the hermetically sealed portions  3  and  3  are formed on the two spots of the long-length tube  30 , which are close to each other. When the welding treatment is completed, the upper welder  25   a  goes up and returns to an original standby position thereof. 
         [0048]    Moreover, simultaneously with the welding treatment by the tube welding unit  25 , the upper stamper  26   b  and cutter  26   c  of the tube cutting/stamping unit  26  also go down to the lower pedestal  26   a , and implement the stamping process and a cutting process for the long-length tube  30 . The two tongue portions  4  and  4  are formed by the stamping process, and the hermetically sealed portions  3  and  3  close to each other are cut by the cutting process. When the cutting/stamping processes are completed, the upper stamper  26   b  and the cutter  26   c  go up and return to original standby positions thereof. 
         [0049]    When the welding treatment and the cutting/stamping processes are completed, the first to third tube feeding units  22  to  24  convey the long-length tube  30  at the predetermined pitch L again, and then stop. Then, the above-described welding treatment and cutting/stamping processes are implemented again. Specifically, the conveying of the long-length tube  30  and such a set of the welding treatment and the cutting/stamping processes are repeated alternately, whereby the plurality of caps  1 A shown in  FIGS. 3A and 3B  are sequentially manufactured from the long-length tube  30 . 
         [0050]    As above, in the present invention, the cap  1 A is formed of the tube  2 , in which one end side is made as the hermetically sealed portion  3  by the welding treatment, and the tongue portion  4  is formed by the stamping process on the other end side. Hence, the welding treatment and the cutting/stamping processes are implemented for the tube  30  formed by the extrusion molding, thus making it possible to fabricate the cap  1 A. Therefore, in comparison with a cap formed by injection molding using a metal mold, good productivity is brought, and cost of equipment is saved. Moreover, the electric wire connecting portion  10  is inserted into the cap  1 A, and the tongue portion  4  is bound with the plurality of electric wires W by the tape  11 , whereby the work to cover the electric wire connecting portion  10  by the cap  1 A is completed. From the above, cost of parts is low, and in addition, the work to cover the electric wire connecting portion  10  is simple. 
         [0051]    In this first embodiment, the plurality of caps  1 A are continuously fabricated from the long-length tube  30 , the tongue portions  4  and  4  of the two caps  1 A and  1 A fabricated adjacent to each other are set at the positions opposed to each other along the longitudinal direction of the long-length tube  30 , and both of the tongue portions  4  and  4  at the opposed positions are formed by the stamping process. Hence, a loss of the material of the plurality of caps  1 A is saved when the caps  1 A are fabricated from the long-length tube  30 , and this contributes to reduction of the cost. 
         [0052]    In this first embodiment, the cap  1 A is manufactured by the welding step of forming the hermetically sealed portion  3  by implementing the welding treatment for the long-length tube  30  at the predetermined pitch L in the longitudinal direction thereof, and by the cutting/stamping process step of cutting the long-length tube  30  so that the hermetically sealed portion  3  can be one end of the cap  1 A, and of implementing the stamping process for the long-length tube  30  in order to form the tongue portion  4  on the other end side of the cut tube  2 . Hence, the plurality of caps  1 A can be continuously fabricated from the long-length tube  30 . Moreover, as the raw material of the cap  1 A, the tube  30  formed by the extrusion molding can be used. Furthermore, the welding treatment and the stamping process are implemented for the tube  30 , whereby each cap  1 A is fabricated. Accordingly, in comparison with the cap formed by the injection molding using the metal mold, good productivity is brought, and the cost of the equipment is saved. Moreover, the electric wire connecting portion  10  is inserted into the cap  1 A, and the tongue portion  4  is bound with the plurality of electric wires W by the tape  11 , whereby the work to cover the electric wire connecting portion  10  by the cap  1 A is completed. From the above, the cap  1 A can be mass-produced, in which the cost of the parts is low, and in addition, the work to cover the electric wire connecting portion is simple. 
         [0053]    In this first embodiment, the tongue portions  4  and  4  of the two caps  1 A and  1 A fabricated adjacent to each other from the long-length tube  30  are set in the same region with respect to the longitudinal direction of the long-length tube  30  and at the positions opposed to each other. In the welding step, the two spots of the long-length tube  30 , which are close to each other, are welded simultaneously, whereby the hermetically sealed portions  3  and  3  are formed in the two spots close to each other. In the cutting/stamping process step, the spot between the hermetically sealed portions  3  and  3  in the two spots close to each other is cut, and the two tongue portions  4  and  4  set at the positions opposed to each other are stamped. In such a way, the cap  1 A is manufactured. Hence, the two caps  1 A and  1 A can be fabricated simultaneously by the welding step and the cutting/stamping process step, each of which is implemented once. Accordingly, this leads to further enhancement of the productivity. Moreover, the loss of the material of the plurality of caps  1 A is saved when the caps  1 A are fabricated from the long-length tube  30 , and this contributes to the reduction of the cost. 
         [0054]    In this first embodiment, the welding step and the cutting/stamping process step are implemented simultaneously, and accordingly, the further enhancement of the productivity can be achieved. 
         [0055]    Moreover, in comparison with an injection molding apparatus using the metal mold, it is possible to install the cap manufacturing apparatus  20  by the side of a production line for manufacturing the wire harness. Such installation of the cap manufacturing apparatus  20  by the side of the production line of the wire harness saves distribution cost, and in addition, makes it possible to manufacture just a required quantity of the caps  1 A and to supply the manufactured caps  1 A to the production line of the wire harness. Accordingly, inventory control and an inventory space can be suppressed to the minimum. 
         [0056]      FIG. 9  is a front view of a cap according to a second embodiment. In  FIG. 9 , in comparison with the cap  1 A of the above-described first embodiment, the cap  1 B of the second embodiment is different therefrom only in that a protruded portion  5  formed by the stamping process is attached onto the end of the tongue portion  4 . Specifically, a stamped shape of such a cut/stamped portion of the first embodiment is partially changed, whereby the protruded portion  5  is formed on the end of the tongue portion  4 . 
         [0057]    Other configurations are similar to those of the above-described first embodiment. Accordingly, the same reference numerals are assigned to the same constituents in the drawing, and a description thereof is omitted. 
         [0058]    In this second embodiment, the protruded portion  5  formed by the stamping process is provided on the end of the tongue portion  4 . Hence, when external force to pull out the cap  1 B from the electric wires is applied to the cap  1 B, the protruded portion  5  of the tongue portion  4  increases frictional force with the electric wires, and accordingly, there is an advantage that the cap  1 B is not detached easily. 
         [0059]      FIG. 10  is a front view of a cap according to a third embodiment. In  FIG. 10 , in comparison with the cap  1 A of the first embodiment, the cap  1 C of the third embodiment is different therefrom only in that a protruded portion  6  formed by heating treatment is attached onto the end of the tongue portion  4 . Specifically, the end of the tongue portion  4  of the cap fabricated by a similar manufacturing method to that of the first embodiment is heated by laser irradiation and the like, and the end is molten and solidified, whereby the protruded portion  6  is formed. 
         [0060]    Other configurations are similar to those of the above-described first embodiment. Accordingly, the same reference numerals are assigned to the same constituents in the drawing, and a description thereof is omitted. 
         [0061]    In this third embodiment, the protruded portion  6  formed by the heating treatment is provided on the end of the tongue portion  4 . Hence, when external force to pull out the cap  1 C from the electric wires is applied to the cap  1 C, the protruded portion  6  of the tongue portion  4  increases frictional force with the electric wires, and the wound tape  11  gets snagged on the protruded portion  6 . Accordingly, there is an advantage that the cap  1 C is not detached easily.