Patent Publication Number: US-6709253-B2

Title: Die for waterproof molding

Description:
This is a Division of application Ser. No. 09/984,919 filed Oct. 31, 2001 now U.S. Pat. No. 6,409,541. The entire disclosure of the prior application(s) is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a waterproof structure in a cable insertion section, that is, a section into which a cable member of the waterproof connector or the like is inserted is waterproofed and to a method of manufacturing the waterproof structure. 
     The present invention also relates to a waterproof molding die for forming a waterproof mold to be attached to wiring material having lead wires provided therein. 
     2. Description of the Related Art 
     In relation to a waterproof connector, an attempt has hitherto been made to block intrusion of liquid into a space defined between an outer peripheral surface of each wire and an inner peripheral surface of a wire insertion hole into which a corresponding wire is to be inserted, by means of attaching a rubber plug to each wire to be assembled (a first related-art example). In another attempt to block intrusion of liquid, there is employed a waterproof structure utilizing a plate-like single-piece rubber plug, wherein a plurality of electric wires to be assembled are fitted into a plurality of previously formed wire conduit sections, thus collectively rendering the electric wires waterproof (a second related-art example). In still another attempt to block intrusion of liquid, there is employed a structure which renders electric wires waterproof by means of filling an electric wire insertion section, into which electric wires are to be inserted, with resin and solidifying the resin (a third related-art example) 
     For example, FIG. 10 shows structure of a waterproof connector  2  utilizing a single-piece rubber  1 . A housing body  3  of the waterproof connector  2  molded from resin has a plurality of terminal attachment sections  3   a  into which connector terminals  5  connected to conductor terminal sections of electric wires  4 , respectively, are to be fitted in an unremovable manner and an electric wire insertion section  3   b  projectingly formed in a substantially-angular cylindrical shape, situated on one end face side of the terminal attachment sections  3   a , and inserted the electric wires  4 . 
     The single-piece rubber  1  is formed from rubber material having a shape of a substantially-rectangular plate and being elastically deformable, the rubber material which is slightly larger than an inner shape of the electric wire insertion section  3   b  so as to come into closely contact with the inner peripheral surface of the electric wire insertion section  3   b  when the single-piece rubber  1  is pushed into and fitted to the electric wire insertion section  3   b . Wire through holes la are formed in the single-piece rubber plug  1  so as to correspond to the terminal attachment sections  3   a , respectively, and each electric wire  4  passes through and is held in a corresponding wire through hole  1   a.    
     The waterproof connector is further provided with a holder body  6  for pressing the single-piece rubber plug  1  fitted into the electric wire insertion section  3   b  from an outside thereof. Similarly, the holder body  6  is formed wire insertion holes  6   a  through which the connector terminals  5  and the electric wires  4  passes so as to correspond to the connector terminals  5  and the electric wires  4 . A latch piece  6   b  is formed so as to extend from each side edge of the holder body  6 . A latch projection  3   c  formed so as to protrude from an outer peripheral side on either side of the electric wire insertion section  3   b  is removably latched in a latch hole  6   c  formed in each latch piece  6   b , thereby pressing the outer side surface of the single-piece rubber plug  1  and unremovably hold the plug  1 . 
     However, the waterproof structure of the waterproof connector according to the first related-art example adopts a method of attaching each of rubber plugs to each of electric wires. Because of this, attaching a rubber plug to a wire involves consumption of time during an assembly operation. Further, use of the rubber plugs hinders miniaturization of a waterproof connector associated with miniaturization of a connector terminal. 
     The waterproof structure according to the second related-art example has a merit of contributing to realization of a compact multi-contact waterproof connector. However, when each electric wire  4  is caused to pass through a corresponding wire through hole la of the single-piece rubber plug  1 , there is a necessity of first squeezing the connector terminal  5  connected to the electric wire  4 . At this time, the connector terminal  5  is squeezed into the wire through hole la while holding the electric wire  4 . In association with miniaturization of the connector terminal  5 , the diameter of the electric wire  4  has become reduced. It is difficult to pass the connector terminals  5  through wire through holes  1  while holding the electric wires  4  due to buckling of the electric wires  4  and the like. 
     Further, as a result of an increase in the number of contacts in a connector, a task for assembling a connector by means of inserting the connection terminal  5  and the electric wire  4  into a corresponding wire through hole la formed in the single-piece rubber plug  1  takes a lot of trouble to be the task difficult. Even when the single-piece rubber plug  1  is used, there is a necessity of a countermeasure for sealing unoccupied wire through holes la through use of a dummy plug or film. 
     The waterproof structure according to the third related-art example obviates a necessity of use of an individual rubber plug to be attached to each electric wire, such as that described in connection with the first related-art example. Further, the waterproof structure according to the third related-art example also obviates a necessity of a task for causing the connector terminal  5  and the electric wire  4  to pass through a corresponding wire through hole la formed in the single-piece rubber plug  1 , such as that described in connection with the second related-art example. On the other hand, the waterproof structure, however, involves solidification of the wire insertion section by means of filling it with resin. Because of this, upon discovery of an attachment failure having arisen when the connector terminal is attached to the terminal attachment section or upon the connector terminal sustaining damage, the plug can be neither replaced or subjected to maintenance. 
     SUMMARY OF THE INVENTION 
     The present invention has been conceived in light of the problems set forth the above and aims at providing a waterproof structure in a cable insertion section in an attempt to improve ease of assembly and maintenance, as well as at providing a method of manufacturing the waterproof structure. 
     According to a first aspect of the invention, there is provided a waterproof structure in a cable insertion section, wherein an inner peripheral surface of the cable insertion section and an outer peripheral surface of a cable member are sealed together in a cable-inserted state in which connector terminals of cable members connected to ends of individual conductors are inserted into the cable insertion section formed in a housing body and are provided at predetermined positions, the waterproof structure comprising: a plug molded on the outer peripheral surfaces of the cable members situated in the cable insertion section and detachably fitted into the cable insertion section with a slight gap between the inner peripheral surface of the cable insertion section and the plug; and a elastically deformable annular sealing body retained in a retention groove formed along an outer peripheral surface of the plug and brought into close contact with the inner peripheral surface of the cable insertion section. 
     According to a second aspect of the invention, there is provided the waterproof structure according to the first aspect of the invention, further comprising a holder member having a cable insertion opening smaller than the plug, wherein the holder member having a cable insertion opening smaller than the plug may be detachably engaged with the cable insertion section from an outer surface of the plug while the cable members are inserted into the cable insertion opening. 
     According to a third aspect of the invention, there is provided a method of manufacturing a waterproof structure in a cable insertion section, wherein an inner peripheral surface of the cable insertion section and an outer peripheral surface of a cable member are sealed together in a cable-inserted state in which connector terminals of cable members connected to ends of individual conductors are inserted into the cable insertion section formed in a housing body and are provided at predetermined positions, the method comprising the steps of: inserting the cable members into a elastically deformable annular sealing body movably to realize the cable-inserted state; detachably fitting a plug into the cable insertion section with a slight gap between the inner peripheral surface of the cable insertion section; molding the plug on the outer peripheral surfaces of the cable members situated in the cable insertion section to form a retention groove for holding the sealing body being in an outer peripheral surface of thereof; and fittingly squeezing the plug into the cable insertion section while the sealing body is retained in the retention groove in the molded plug to bring the sealing body into close contact with the inner peripheral surface of the cable insertion section. 
     According to a fourth aspect of the invention, there is provided the method of manufacturing a waterproof structure in a cable insertion section according to the third aspect of the invention, further comprising the steps of: inserting the cable members into a cable insertion opening of the holder body having the cable insertion opening smaller than the plug before the step of inserting the cable members into the sealing body; and detachably engaging the holder body with the cable insertion section while the plug is fittingly squeezed into the cable insertion section. 
     According to a fifth aspect of the invention, there is provided the method of manufacturing the waterproof structure in the cable insertion section according to any one of the third and fourth aspects of the invention, wherein the cable members are a plurality of electric wires; elastically deformable soft elastic members are respectively provided on edges of openings for leading a cable, which are opposed to each other and is situated on either side of two split dies with reference to a longitudinal direction of the electric wires; and molding material is poured into a cavity while the electric wires are put together in a bundle and sandwiched by elastic deformation of the elastic members of the split dies to mold the plug. 
     According to a sixth aspect of the invention, there is provided A waterproof mold die for molding a waterproof mold having a large-diameter flange section to be attached to a wiring member having lead wires therein and a small-diameter seal section, the waterproof mold die comprising: a die main body having an upper die and a lower die, the dies constituting a molding surface for the flange section of the waterproof mold; and a cylindrical die having single-piece structure, at least a part of the cylindrical die supported by the upper and lower dies of the die main body, wherein a molding surface for the seal section of the waterproof mold is provided in the cylindrical die. 
     By means of the foregoing structure, when fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die, there is formed the waterproof mold having the flange section matching the molding surface defined between the upper and lower dies of the die main body and the seal section having the shape matching the molding surface of the cylindrical die, thereby preventing formation of burrs in an outer peripheral surface of the seal section. 
     According to a seventh aspect of the invention, there is provided the waterproof mold die according to the sixth aspect of the invention, wherein an insertion section for the wiring member is provided in a junction between the upper and lower dies constituting the die main body; and an elastic sealing material is provided in the insertion section. 
     By means of the structure set forth, while the wiring member remains inserted into the insertion section, fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die. As a result, the waterproof mold is formed while the waterproof mold is integrally attached to the outer peripheral surface of the wiring member. 
     According to a eighth aspect of the invention, there is provided the waterproof mold die according to any one of the seventh and eighth aspects of the invention, wherein one end of the cylindrical die is exposed to the outside of the die main body; a retainer die formed of split dies for retaining the wiring member is provided in the exposed portion of the cylindrical die; a surface tapered to a tip is formed on an outer peripheral section of the retainer die; and a mount hole having another tapered surface, which surface becomes wider toward the outside and matches the tapered surface of the retainer die, is formed in the cylindrical die. 
     By means of the foregoing structure, while the wiring member remains inserted in the insertion section, fused insulation material is poured into the molding surface constituted by the die main body and the cylindrical die. As a result, the waterproof mold is formed while the waterproof mold is integrally attached to the outer peripheral surface of the wiring material. Subsequently, the retainer die is pulled from the mount hole of the cylindrical die, and the split dies are opened, thereby facilitating a task for removing the cylindrical die from the waterproof mold while the upper and lower dies of the die main body remain in an opened state. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing a waterproof structure according to a first embodiment of the present invention. 
     FIG. 2 is an explanatory view showing procedures for manufacturing a waterproof structure. 
     FIG. 3 is an explanatory view showing the procedures for manufacturing a waterproof structure. 
     FIG. 4 is an explanatory view showing the procedures for manufacturing a waterproof structure. 
     FIG. 5 is an explanatory view showing the procedures for manufacturing a waterproof structure. 
     FIG. 6 is an explanatory view showing the procedures for manufacturing a waterproof structure. 
     FIG. 7 is a fragmentary perspective view showing a second embodiment of the present invention. 
     FIG. 8 is a cross-sectional view showing a waterproof structure in an assembled state. 
     FIG. 9 is a cross-sectional view showing a third embodiment of the present invention. and 
     FIG. 10 is an exploded perspective view showing an example related-art waterproof structure. 
     FIG. 11 is a cross-sectional view showing an embodiment of a die for forming a waterproof mold according to the present invention. 
     FIG. 12 is a cross-sectional view showing a state in which insulation material is poured into the die. 
     FIG. 13 is a perspective view showing the specific structure of a waterproof mold. 
     FIG. 14 is a descriptive view showing a mounted state of the waterproof mold. 
     FIG. 15 is a cross-sectional view showing another embodiment of a die for forming a waterproof mold according to the present invention. 
     FIG. 16 is a perspective view showing an example of a waterproof mold formed by use of a related-art die. 
     FIG. 17 is a descriptive view showing a mounted state of the waterproof mold. and 
     FIG. 18 is a cross-sectional view showing an example of a related-art die. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     [Embodiment 1] 
     A first embodiment of the present invention will be described hereinbelow with reference to drawings. FIG. 1 is an exploded perspective view of a waterproof connector  10 . A housing body  11  of the waterproof connector  10  is molded from resin or the like material. A connector terminal  13  is press-fitted to an end of each of electric wires  12  serving as a cable member, whereby the connector terminal  13  is connected to a conductor of the corresponding electric wire  12 . A plurality of terminal attachment sections  11   a  are provided in the housing body  11 , wherein each connector terminal  13  is fitted into and prevented from dropping out from a corresponding terminal attachment section  11   a . An electric wire insertion section  11   b , which serves as a cable insertion section and is projectingly formed in a substantially-angular cylindrical shape, is situated along one end surface side of the terminal attachment sections  11   a  and enables insertion of respective electric wires  12 . 
     A plug member  14 , which has been molded such that the electric wires  12  are put together in a center thereof, is provided in the vicinity of the end of each of electric wires  12 . The plug body  14  is formed into a shape of a substantially-rectangular flat plate and is slightly smaller than the electric wire insertion section  11   b  so as to be removably fitted thereinto with a slight clearance between the plug body  14  and the inner peripheral surface of the electric wire insertion section  11   b . The plug body  14  is fixed to the outer peripheral surface of each electric wire  12  in a fluid-tight manner. 
     A retention groove  14   a  (see FIG. 4) detachably holding an annular, elastically deformable O-ring  15  is formed along the outer peripheral surface of the plug body  14 . When the plug body  14  is fitted into the electric wire insertion section  11   b  with the O-ring  15  being held in the retention groove  14   a , there is achieved a sealed state in which the O-ring  15  closely contacts with the inner peripheral surface of the electric wire insertion section  11   a  and the outer peripheral surface of the plug body  14  as a result of elastic deformation of the O-ring  15 . 
     The waterproof connector is further provided with a holder body  16  which is molded from resin or the like material and presses the plug body  14  fitted into the electric wire insertion section  11   b  from the outside thereof. The holder body  16  is formed into a shape of a substantially-rectangular flat plate so as to be removably fitted into the electric wire insertion section  11   b . An elongated electric wire insertion opening  16   a  is formed in a center of the holder body  16  as a cable insertion opening. The electric wire insertion opening  16   a  is smaller than the plug body  14 , and the electric wires  12  are to be loosely inserted into the electric wire insertion opening  16   a.    
     A latch piece section  16   b  is formed so as to extend from either side edge of the holder body  16 . A latch protrusion  11   c  formed on the outer peripheral surface on either side of the electric wire insertion section  11   b  is removably latched into a latch hole  16   c  formed in each latch piece section  16   b , thereby pressing the outer surface of the plug body  14  fitted into the electric wire insertion section  11   b  to hold and prevent from dropping out. 
     A method of manufacturing the waterproof connector  10  will now be described with reference to FIGS. 2 through 6. 
     At first, the electric wires  12 , the end of each wire having the connector terminal  13  crimped thereon, are caused to pass through the electric wire insertion opening  16   a  formed in the holder body  16  and through the O-ring  15 . Subsequently, each connector terminal  13  is fitted to a predetermined position in the corresponding terminal attachment section  11   a  via the electric wire insertion section  11   b  of the housing body  11 . At this time, each connector terminal  13  situated in the predetermined position is unremovably latched by a lance  18  provided in the housing body  11  and by a retainer  19  fixed to the housing body  11 . Further, the retainer  19  unremovably holds a elastically deformable waterproof ring  20 . 
     After attachment of the connector terminals  13 , the electric wires  12  are put together in a bundle and pinched, for example, vertically from both sides thereof in the vicinity of the outside of the electric wire insertion section  11   b  by means of two split dies  21  and  22 . Elastically deformable soft elastic members  25  are provided by an adhesive or the like along edge portions  23 ,  24  of openings for leading a cable, which are opposed to each other and positioned on both sides of the split dies  21 ,  22  with reference to a longitudinal direction of the electric wires  12 . The elastic members  25  are brought into close contact with the outer peripheral section of the bundled electric wires  12  while the electric wires  12  are put together in a bundle and sandwiched by means of elastic deformation of the elastic members  25 . 
     A cavity  21   a  defined by the split die  21  and a cavity  22   a  defined by the split die  22  are filled with a molding member, such as thermosetting resin, thermoplastic resin, or a hot-melt adhesive by way of an unillustrated infusion channel, with the electric wires  12  being sandwiched between the split dies  21  and  22 , and the thus-filled molding member is solidified, thereby molding the plug  14 . At this time, use of a hot-melt adhesive which obviates a necessity for pre-heating the split dies  21  and  22  is desirable in terms of productivity. For instance, in a case that cladding material of the electric wire  12  is polyvinyl chloride (PVC), dimer-acid-based polyamide is used. In a case where cladding material of the electric wire  12  is polyethylene (PE), an olefin hot-melt adhesive is used. 
     Protruding fluted sections  21   a ,  22   a  are formed in inner surfaces of the split dies  21 ,  22  in a circumferential direction thereof, respectively. A retention groove  14   a  is formed along an outer peripheral surface of the plug  14  that has been removed from the cavities  21   a  and  22   a  by means of opening the dies. 
     The O-ring  15  is fittingly retained in the retention groove  14   a  of the thus-molded plug  14  by means of elastic deformation of the O-ring  15 . In the thus-retained state, the plug  14  is fittingly squeezed into the electric wire insertion section  11   b . By means of the fitting and squeezing action, the O-ring  15  is elastically deformed. As a result, there is achieved a sealed state in which the O-ring  15  is brought into close contact with the inner peripheral surface of the electric wire insertion section  11   b  and the outer peripheral surface of the plug  14 . 
     In this state, the holder body  16  is moved to the wire insertion section  11   b , thereby causing the latch protrusions  11   c  to latch the latch holes  16   c  of the latch pieces  16   b , respectively. 
     As has been described, under the manufacturing method according to the present embodiment, the plug  14  is molded in close contact with the outer peripheral of the electric wires  12  while the wires  12  are put together in a bundle. Hence, there is no necessity for attaching a rubber plug to each electric wire and for causing the connector terminal  5  and the electric wire  4  to pass through the wire through hole la of the single-piece rubber plug  1 , which have been required in the related art, thereby enabling improvement in ease of assembly. Thus, the manufacturing method is also suitable for realizing a compact multi-contact connector. 
     The O-ring  15  is fittingly squeezed into the electric wire insertion section  11   b  while being held in the retention groove  14   a  of the plug  14 . As a result, there can be sealed a space between the inner peripheral surface of the electric wire insertion section  11   b  and the outer peripheral surface of the plug  14 . Upon discovery of an attachment failure having arisen when the connector terminal  13  is attached to the terminal attachment section  11   a  or upon the connector terminal  13  sustaining damage, the plug  14  can be removed from the electric wire insertion section  11   b . Therefore, ease of maintenance of the connector after assembly can also be improved. 
     The soft elastic members  25  are provided at the edges  23 ,  24  of the openings for leading a cable in the split dies  21 ,  22 . Hence, the elastic members  25  can come into close contact with the outer peripheral surfaces of the electric wires  12 , thereby remarkably preventing occurrence of leakage of molding material when the cavities  21   a  and  22   a  are filled with molding material. 
     Further, the holder body  16  can effectively prevent the plug body  14  from detaching from the inside of the electric wire insertion section  11   b.    
     [Embodiment 2] 
     FIGS. 7 and 8 show a second embodiment of the present invention, wherein a flexible flat cable (FFC)  27  is adopted as a cable member. Those constituent elements which are identical with those employed in the embodiment 1 are assigned the same reference numerals, and their repeated explanations are omitted. 
     Even in the present embodiment, if the plug  14  is molded on the outer peripheral surface of the FFC  27  and if the plug  14  is fittingly squeezed into the cable insertion section  11   d  in the same manner as mentioned above with the O-ring  15  being held, a sealed state is achieved. 
     Accordingly, even in the present embodiment, there is yielded the same advantage as that yielded in the first embodiment. 
     [Embodiment 3] 
     FIG. 9 shows a third embodiment of the present invention, wherein the present invention has been applied to a cable insertion section  28   a  of a housing body  28  including a case, for example, a unit case such as an ECU or a module case. Those constituent elements which are identical with those employed in the first or second embodiment are assigned the same reference numerals, and their repeated explanations are omitted. 
     The housing body  11  attached to the FFC  27  is removably connected to a connector section  30  of a substrate  29  housed in the housing body  28 . The portion of the FFC  27  inserted into the cable insertion section  28   a  is molded with a plug  31  in the same manner as mentioned above. The housing body  28  is sealed with the O-ring  15  retained on the plug body  31 . 
     Even in the present embodiment, there is yielded the same advantage as that yielded in the first embodiment. 
     The above described embodiments show the structures which adopt the plurality of electric wires  12  and the FFC  27  as a cable member. However, a cable member may also be a form of a twist line in which a plurality of electric wires are twisted, a flexible print board (FPC), a ribbon cable, or another sheet-like flat cable. Moreover, there may also be employed a structure having a mix of line materials of multiple types, as in a case of a combination of the electric wires  12  and the FFC  27 . In this case, the plug  14  or  31  is molded, and good sealing can be achieved regardless of a cross-sectional profile of a line material. 
     There has been shown a structure wherein the O-ring  15  is used as a tool ring body. A rubber ring having a plurality of lips, such as a waterproof ring  20 , may also be employed. 
     [Embodiment 4] 
     As shown in FIG. 16, the waterproof mold according to the above embodiments may have a seal section  103  having small diameter to be fitted into an opening or the like area in the partition section, and a flange section  102  having large diameter. As shown in FIG. 17, an O-ring  123  may be provided between the seal section  103  of the waterproof mold  104  and an opening section  122  of the partition section  121 , thereby effectively sealing the fitting portion of the seal section  103 . 
     FIG. 18 shows a die for forming the waterproof mold. The die comprises an upper die  150  and a lower die  160  for defining a molding surface matching a shape of a waterproof mold  104 . While the upper die  150  and the lower die  160  are clamped, insulating material in a fused state is poured along the molding surface, thereby forming the waterproof mold  104 . 
     As mentioned above, when the waterproof mold  104  is formed by use of the molding die having the upper die  150  and the lower die  160  in the manner as mentioned above, the insulating material poured along the molding surface sometimes leaks from a junction between the upper die  150  and the lower die  160 . As shown in FIG. 16, formation of burrs along the outer peripheral surface of the waterproof mold is inevitable. For this reason, as shown in FIG. 17, in case that the seal member including the O-ring  123  is interposed between the seal section  103  of the waterproof mold  104  to be fitted into the opening section  122  of the partition section  121  and the opening section  122 , thereby sealing a space between the seal section  103  and the opening section  122 , clearance due to presence of the burrs  124  is formed between the seal section  103  of the waterproof mold  104  and the seal member including the O-ring  123 , thereby deteriorating a sealing characteristic. 
     The embodiment 4 has been conceived in light of the above-described drawback and aims at providing a die for forming a waterproof mold capable of preventing occurrence of deterioration of a sealing characteristic due to formation of burrs in an outer peripheral surface of a waterproof mold during formation of the waterproof mold. 
     FIGS. 11 and 12 show a die for forming a waterproof mold according to the embodiment 4. The die is used for forming a waterproof mold  104 . The waterproof mold  104  has a flange section  102  of large cross sectional area and a seal section  103  of small cross sectional area (hereinafter an element of large cross-sectional area is referred to as being of “large diameter,” and an element of small cross-sectional area is referred to as being of “small diameter.”). The water proof molding  104  is att elastic sealing material ached to wiring material  101  including a flat cable having a plurality of lead wires provided therein. The die comprises a die main body  107 , a cylindrical die  108 , and a retainer die  110 . The die main body  107  has an upper die  105  and a lower die  106 , which constitute a molding surface for the flange section  102  of the waterproof mold  104 . The die  108  has a single-piece structure, and at least a part of the die  108  is retained by the upper and lower dies  105  and  106  of the die main body  107 . The retainer die  110  is to be disposed in a mount hole  109  formed in the cylindrical die  108 . 
     Each of the upper and lower dies  105  and  106  of the die main body  107  has an exterior wall section  111  constituting an end face section of the molding surface for the flange section  102 , and a large-diameter cylindrical section  112  constituting an outer peripheral section of the molding surface. A step section serving as a retaining section  113  for holding the cylindrical die  108  is formed in the cylindrical section  112 . A notch to become an insertion section for the wiring material  101  is formed in the exterior wall section  111  at a junction section between the upper die  105  and the lower die  106 . Elastic sealing material  114  made of heat-resisting rubber material or the like is fixed to the insertion section for the wiring material  101 , for preventing leakage, to the outside, of fused insulation material poured into the die. 
     The cylindrical die  108  has a small-diameter cylindrical section  115  and an exterior wall section  116 . The cylindrical section  115  constitutes a molding surface for the seal section  103  of the waterproof mold  104 , and the exterior wall section  116  constitutes an end face section of the molding surface. The cylindrical section  114  is sandwiched between the upper die  105  and the lower die  106  of the die main body  107 , whereby the exterior wall section  116  is retained by the die main body  107  while being exposed to the outside. A mount hole  109  is formed in a center of the exterior wall section  116 . The mount hole  109  is tapered so as to become wider toward the outside, and the tapered surface of the mount hole  109  corresponds to a tapered surface  107  formed on an outer peripheral surface of the retainer die  110 , the surface  107  being tapered to become narrower toward the tip thereof. 
     The retainer die  110  has a pair of upper and lower split dies  118  and  119  to be fitted into the mount hole  109 . The surface  117  tapered to become narrower toward the tip thereof is formed on the outer peripheral section of the retainer die  110 . A notch to become an insertion section for the wiring material  101  is formed in a junction between the split dies  118  and  119 . An elastic sealing material  120  made of heat-resistant rubber material or the like is fixed to the insertion section for the wiring material  101  for preventing leakage, to the outside, of fused insulation material poured into the die. 
     In order to form the waterproof mold  104  through use of the die having the foregoing configuration, the upper and lower dies  105  and  106  of the die main body  107  are closed while the wiring material  101  is inserted into the cylindrical die  108  to retain the cylindrical section  115  of the cylindrical die  108  by the retaining section  113  of the die main body  107  and to clamp the wiring material  101  between the elastic seal members  114  provided in the insertion section of the die main body  107 . Subsequently, the split dies  118  and  119  of the retainer die  110  are inserted into the mount hole  109  of the cylindrical die  108  to clamp the wiring material  101  by the elastic sealing materials  120  provided in the insertion section of the retainer die  110 . 
     Fused insulation material; for example, liquid silicon rubber, is poured along the molding surface defined by the die main body  107 , the cylindrical die  108 , and the retainer die  110 , and the thus-poured insulation material is solidified. Subsequently, the retainer die  110  is pulled from the mount hole  109  of the cylindrical die  108  to open the split dies  118  and  119 . Further, the upper die  105  and the lower die  106  of the die main body  107  are vertically separated to open. Next, the seal section  103  of the waterproof mold  104  formed from the insulation material is removed from the cylindrical die  108 . As a result, as shown in FIG. 13, there is eventually formed the waterproof mold  104  having the large-diameter flange section  102  and the small-diameter seal section  103 , which are formed integrally so as to cover the wiring material  101 . 
     As mentioned above, there are provided the die main body  107  and the cylindrical die  108  of single-piece structure, wherein the main body  107  comprises the upper die  105  and the lower die  106 , which constitute the molding surface for the flange section  102  of the waterproof mold  104  and at least a part of the cylindrical die  108  is retained by the upper die  105  and the lower die  106  of the die main body  107 . The molding surface to be used for molding the seal section  103  of the waterproof mold  104  is formed in the cylindrical die  108 . As a result, there is not formed a junction surface, which would otherwise be caused by use of a split type die for the molding surface of the cylindrical die  108 . Thus, there can be prevented generation of burrs in the outer peripheral surface of the seal section  103  formed by the molding surface of the cylindrical die  108 . 
     As shown in FIG. 14, When the wiring material  101  to which the waterproof mold  104  attached is inserted into the partition section  121  and a seal member having the O-ring  123  and the like is disposed between the seal section  103  of the waterproof mold  104  to be fitted into the opening section  122  formed in the partition section  121  and the opening section  122 , there is not formed a clearance between the seal section  103  and the O-ring  123  due to presence of burrs. Thus, the insertion section for the wiring material  101  can be sealed without fail by means of the seal member having the O-ring  23  and the like member, thereby effectively preventing intrusion of water into the partition section  121  via the opening  122 . 
     In the embodiment described above, the notch for constituting the insertion section for the flat wiring material  101  is formed in the junction between the upper die  105  and the lower die  106 , which constitute the die main body  107 . Further, the elastic sealing material  113  is provided in the insertion section. Hence, even when fused insulation material is poured along the molding surface defined by the die main body  107 , the cylindrical die  108 , and the like while the wiring material  101  remains inserted in the insertion section, the insulation material does not leak from the insertion section of the wiring material  101 . Filling the molding surface with the insulation material, the waterproof mold  104  is formed while being integrally attached to the outer peripheral surface of the wiring material  101 . 
     As shown in the embodiment described above, one end of the cylindrical die  108  is exposed to the outside of the die main body  107 . The retainer die  110  having the split dies  118  and  119  for retaining the wiring material  101  is provided in the exposed portion of the cylindrical die  107 . The surface  117  tapered to become narrower toward the tip is formed on the outer peripheral section of the retainer die  110 . Further, the mount hole  109  having a tapered surface matching the tapered surface  117  is formed in the cylindrical die  108 . In this case, while the retainer die  110  is disposed in the mount hole  109  of the cylindrical die  108 , the upper die  105  and the lower die  106  of the die main body  107  are closed to retain the cylindrical die  108 . In this state, fused insulation material is poured along the molding surface, whereby the waterproof mold  104  is formed while being integrally attached to the outer peripheral surface of the wiring material  101 . 
     The retainer die  110  is pulled along the tapered surface formed in the mount hole  109  of the cylindrical die  108  to open the split dies  118  and  119 , which constitute the retainer die  110 , thereby releasing the wiring material  101  from a retained state. Hence, after the upper and lower dies  105  and  106  of the die main body  107  have been opened, the cylindrical section  115  of the cylindrical die  108  and the seal section  103  of the waterproof mold  104  are separated, thereby facilitating a task for releasing the cylindrical die  108 . 
     In the present embodiment, a slit-shaped notch which is to act as an insertion section for the wiring material  101  is formed in a junction between the split dies  118  and  119  constituting the retainer die  110 . Further, the elastic sealing material  120  is provided in the insertion section. Hence, even when fused insulation material is poured along the molding surface defined by the die main body  107 , the cylindrical die  108 , and the retainer die  110  while the wiring material  101  remains inserted in the insertion section, the insulation material does not leak from the insertion section of the wiring material  101 . Filling the molding surface with insulation material, the waterproof mold  104  is formed while being integrally attached to the outer peripheral surface of the wiring material  101 . 
     In this embodiment described above, the cylindrical section  115  of the cylindrical die  108  is retained by the upper and lower dies  105  and  106  of the die main body  107  and the exterior wall section  115  of the cylindrical die  108  is constituted so as to be exposed to the outside. In stead of the above construction, as shown in FIG. 15, a cylindrical die  108   a  may be provided in a die main body  107   a  having an upper die  105   a  and a lower die  106   a  so as to cover the entire molding surface for the waterproof mold material  104 , and the entirety of the cylindrical die  108   a  may be retained by the die main body  107   a . In this case, it is desirable to form a notch serving as an insertion section for the wiring material  101  in each end of the die main body  107   a  and to dispose elastic sealing material  114  in the insertion section for preventing occurrence of leakage of insulation material. 
     As mentioned above, according to the waterproof structure in a cable insertion section and the method of manufacturing the waterproof structure of the present invention, a cable member is loosely inserted into a resiliently-deformable annular seal ring body and sequentially, a plug is molded on an outer peripheral surface of the cable member situated outside the cable insertion section. The plug is removably fitted into the cable insertion section with a slight gap between the inner peripheral surface of the cable insertion section and the plug. A retention groove for holding the seal ring body is formed along an outer peripheral surface of the plug. The plug is fittingly squeezed into the cable insertion section with the seal ring being retained in the retention groove of the molded plug, thereby bringing the sealing ring body into close contact with the inner peripheral surface of the cable insertion section. There is yielded the advantage of improving ease of assembly and ease of maintenance of a connector after assembly. 
     If the holder body is removably engaged in the cable insertion section while the plug is fittingly squeezed into the cable insertion section, there is yielded an advantage of the ability to effectively prevent removal of the plug from the cable insertion section by means of the holder body. 
     A resiliently-deformable soft elastic member is provided on the edge of an opening formed in each of two split dies for leading a cable. The elastic member is situated on either side with reference to the longitudinal direction of electric wires, and the elastic members are opposed to each other. Cavities are filled with molding material while electric wires are tied in a bundle and sandwiched by means of resilient deformation of the elastic members of the split dies, thereby molding a plug. As a result, the elastic members are resiliently deformed and are brought into intimate contact with the outer peripheral surface of each electric wire. There is yielded the advantage of the ability to prevent occurrence of leakage of molding material, which would otherwise be caused when the cavities are filled with molding material. 
     As has been described, the present invention also provides a waterproof mold die for molding a waterproof mold, the mold having a large-diameter flange section to be attached to a wiring material having lead wires provided therein and a small-diameter seal section, the die comprising a die main body formed from an upper die and a lower die, the dies constituting a molding surface for a flange section of the waterproof mold; and a cylindrical die of single-piece structure, at least a part of the die being supported by the upper and lower dies of the die main body, wherein a molding surface for the seal section of the waterproof mold is provided in the cylindrical die, thereby preventing formation of burrs in an outer peripheral section of the seal section, which would otherwise be caused by a molding surface of the cylindrical die.