Patent Publication Number: US-2017368729-A1

Title: Manufacturing method of wire harness

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Japanese Patent Application No. 2016-124874 filed on Jun. 23, 2016, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to the manufacturing method of a wire harness. 
     Description of Related Art 
     For water stop structures of a wire harness in which a plurality of electric wires are bundled, there are those which use a single liquid water stop (silicone), butyl rubber, or the like. As illustrated in  FIG. 14A , in the water stop structure using the single liquid water stop, an electric wire bundle is divided into individual electric wires  501 , and a silicon  503  is applied, caused to conform, formed, and solidified. The outer periphery of the solidified silicon  503  is covered by a sheet member  505 . In the wire harness to which the water stop structure is applied in this manner, a grommet  507  is externally fitted to the outer periphery of the sheet member  505 . The grommet  507  waterproofs a space between the sheet member  505  and a harness insertion hole (not illustrated) such as a vehicle body panel. 
     As illustrated in  FIG. 14B , the water stop structure which uses the butyl rubber is such that the electric wire bundle is divided into the individual electric wires  501 , placed on a butyl rubber  509 , the butyl rubber  509  and the electric wires  501  are laid repeatedly, and the spaces between the electric wires are filled with the butyl rubber  509  under pressure and formed. An adhesive tape  511  is wound around the outer periphery of the butyl rubber  509 . In the wire harness to which the water stop structure is applied in this manner, a seal sponge  513  is wound around the outer periphery of the adhesive tape  511 . The seal sponge  513  waterproofs the space between the adhesive tape  511  and the harness insertion hole (not illustrated). 
     [Patent Document 1] JP-A-2011-172412 
     According to a related art, in a water stop structure by a one-component water stop, a gap between the electric wires is filled with a water stop agent (silicon  503 ), and the water stop agent adheres to the electric wire coating. Therefore, although the water stop performance is excellent, since it is difficult to manage the water stop agent and several hours are necessary for the water stop agent to solidify, workability is not good. In the water stop structure which uses the butyl rubber  509  described above, the spaces between the electric wires are filled with the water stop agent (the butyl rubber  509 ), and since the butyl rubber itself is soft, easily conformable, and yet has adhesiveness, if the filling is reliably performed, the water stop performance is excellent; however, there is a problem in that it is difficult to control the amount of butyl rubber which is used. Furthermore, the water stop structure which uses the butyl rubber  509  has poor workability such that the butyl rubber  509  is sticky and sticks to hands, and it is difficult to confirm the filling status. 
     As a technique capable of being applied to a water stop structure, a mold structure is known in which the outer periphery of an electric wire bundle is molded with a resin material (refer to Patent Document 1 or the like). However, with such a mold structure, when three or more electric wires are bundled, gaps (resin unfilled space) are formed which are spaces between adjacent electric wires which may not be filled with resin. Such a resin unfilled space may not be visually observed from the outside, and it is extremely difficult to determine to what extent the resin can be filled tightly in small gaps between the electric wires. Although it is possible to measure gaps by conducting a destructive inspection, it is only a sampling inspection, and it is impossible to inspect all the products. In all of these mold structures, the molding is performed using an ordinary injection molding machine. Therefore, facilities become large-scaled. 
     SUMMARY 
     One or more embodiments provide a manufacturing method of a wire harness which is capable of easily suppressing a water entrance amount which infiltrates from an electric wire group insertion part. 
     Means for Solving the Problem 
     In an aspect (1), one or more embodiments provide a manufacturing method of a wire harness which includes at least one bundle of an electric wire group in which a plurality of electric wires are linearly arranged, and a damming part made of a resin material, wherein the damming part surrounds a part of the electric wire group in an extending direction of the electric wire group, and wherein the damming part includes an outer periphery shape part according to an inner peripheral shape of an electric wire group insertion part, the manufacturing method including disposing a part of the one bundle of the electric wire group in a harness housing part and mold clamping an upper mold and a lower mold in which the harness housing part is formed on a pair of divided surfaces, and performing low pressure injection of a larger amount of molten resin than a volume of a cavity into the cavity, so that the resin material with which the cavity is filled protrudes from gaps between flat deburring surfaces and adjacent electric wires. The harness housing part includes the cavity so as to mold the damming part and includes the flat deburring surfaces which clamp an outer periphery of the one bundle of the electric wire group at both outside end parts of the cavity which face each other in the extending direction of the electric wire group. 
     According to the aspect (1), a single row electric wire group is disposed in a harness housing part, and when mold clamping an upper mold and a lower mold which are aligned so as to interpose the single row electric wire group in parallel with flat deburring surfaces which are formed on both outside end parts of a cavity which runs along an extending direction of the electric wire group, a molding space for molding a damming part is defined between the upper mold and the lower mold. With the gaps which are formed between the flat deburring surfaces and the spaces between the adjacent electric wires remaining vacant, a greater amount of the molten resin than the volume of the cavity is injected at low pressure into the cavity. As a result, the excess part of the molten resin with which the cavity is filled protrudes from the gaps between the flat deburring surfaces and the spaces between the adjacent electric wires. Here, since the gaps between the electric wires in the cavity are larger than the gaps which are formed between the flat deburring surfaces and the spaces between the adjacent electric wires, it is possible to assume that the gaps between the electric wires in the cavity are filled with the molten resin due to the molten resin protruding from the gaps between the flat deburring surfaces and the spaces between the adjacent electric wires. In other words, by visually observing the resin material (the burrs) protruding from the gaps between the electric wires through side surface and the spaces between the adjacent electric wires in the damming part, it is possible to confirm that the gaps between the electric wires in the damming part are filled with the resin material. Since the molten resin which enters the cavity has low pressure during press fitting and does not leak out from the gaps between the flat deburring surfaces and the spaces between the adjacent electric wires until the cavity is filled, a large amount of the resin will not leak out from the gaps between the flat deburring surface and the spaces between the adjacent electric wires. 
     In an aspect (2), the resin material includes polypropylene. 
     According to the aspect (2), by using polypropylene which has excellent hinge characteristics as the resin material, the resin material which protrudes from the gaps does not easily bend and fall, and the resin material does not scratch the electric wire coating, and does not fall to become foreign matter. 
     According to the manufacturing method of a wire harness according to the present invention, it is possible to easily suppress a water entrance amount which infiltrates from an electric wire group insertion part. 
     The invention has been briefly described above. Further, the details of the invention will become more apparent by reading the embodiments for carrying out the invention (hereinafter referred to as the “exemplary embodiments”) described hereinafter with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  represent a water entrance countermeasure structure of a wire harness according to a first exemplary embodiment.  FIG. 1A  is a perspective diagram in which a damming part is provided in a single stage electric wire group, and  FIG. 1B  is an enlarged diagram of an A part in  FIG. 1A . 
         FIG. 2  is a sectional diagram of a damming part illustrated in  FIG. 1A  taken along an II-II line. 
         FIG. 3  is a sectional diagram of the main parts in the vicinity of a deburring surface in a state in which a cavity of a mold is filled with a molten resin. 
         FIG. 4  is an exploded perspective diagram of the main parts representing a device connection structure which uses a wire harness which is provided with the water entrance countermeasure structure illustrated in  FIG. 1A . 
         FIG. 5  is a perspective diagram of a low pressure injection molding machine. 
         FIG. 6A  is a schematic sectional diagram for explaining a state in which a single row electric wire group is covered with a resin material.  FIG. 6B  is a schematic sectional diagram explaining a state in which an electric wire group in which three or more electric wires are bundled is covered with a resin material. 
         FIG. 7A  is a perspective diagram of a damming part according to a second exemplary embodiment.  FIG. 7B  is a lateral sectional diagram of the damming part illustrated in  FIG. 7A .  FIG. 7C  is an enlarged diagram of a B part in  FIG. 7B . 
         FIG. 8  is an exploded perspective diagram of the main parts representing a device connection structure which is provided with a water entrance countermeasure structure of a wire harness according to a third exemplary embodiment. 
         FIG. 9A  is a perspective diagram of the damming part illustrated in  FIG. 8 .  FIG. 9B  is a lateral sectional diagram of a state in which the damming part illustrated in  FIG. 9A  is fitted into a through hole of the electric wire group insertion part.  FIG. 9C  is an enlarged diagram of a C part in  FIG. 9B . 
         FIG. 10A  is a perspective diagram illustrating a modification example of the damming part illustrated in  FIG. 9A .  FIG. 10B  is a lateral sectional diagram of a state in which the damming part illustrated in  FIG. 10A  is fitted into the through hole of the electric wire group insertion part.  FIG. 10C  is an enlarged diagram of a D part in  FIG. 10B . 
         FIG. 11A  is a perspective diagram of a damming part according to a fourth exemplary embodiment of the present invention as viewed from a seating surface side.  FIG. 11B  is a perspective diagram of a modification example of the damming part illustrated in  FIG. 11A  as viewed from the seating surface side. 
         FIG. 12A  is a perspective diagram of a comparative example of the damming part illustrated in  FIG. 11A  as viewed from the seating surface side.  FIG. 12B  is a longitudinal sectional diagram of the damming part illustrated in  FIG. 12A .  FIG. 12C  is a sectional diagram taken along an XII-XII line in  FIG. 12B . 
         FIG. 13A  is a perspective diagram of a damming part according to a fifth exemplary embodiment of the present invention.  FIG. 13B  is a sectional diagram of a state in which the damming part illustrated in  FIG. 13A  is fitted into the through hole of the electric wire group insertion part taken along an XIII-XIII line. 
         FIG. 14A  is a lateral sectional diagram of a water stop structure which uses a single liquid water stop of the related art.  FIG. 14B  is a lateral sectional diagram of a water stop structure which uses butyl rubber. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the exemplary embodiments of the present invention will be described with reference to the drawings. 
     As illustrated in  FIG. 1A , the water entrance countermeasure structure of a wire harness  100  according to the first exemplary embodiment of the present invention is provided with an electric wire group  13  and a damming part  15  as the main components, where the electric wire group  13  is formed of a plurality of electric wires  11  which are installed together in a horizontal direction, and the damming part  15  is made of a resin. 
     The plurality of electric wires  11  are linearly arranged in a row in a diameter direction in the electric wire group  13 . In each of the electric wires  11 , the outer periphery of the conductor is covered with an insulating resin. The plurality of electric wires  11  is provided so that at least one row lines up in the diameter direction in the electric wire group  13  according to the present invention. The expression “at least one row” means that a plurality of rows may be disposed in a multi-staged formation. However, in this case, as described later, the electric wire group of each stage is disposed separated from those of the other stages. 
     The damming part  15  is molded integrally to surround a part of the electric wire group  13  in an extending direction. The damming part  15  is integrally molded so as to include an outer periphery shape part  19  corresponding to the inner peripheral shape of an electric wire group insertion part  29  which is described later, and a pair of side surfaces extending along the extending direction of the electric wire group  13 . The outer periphery shape part  19  of the damming part  15  can be molded in a trapezoidal cross section taken along a plane which is orthogonal to the extending direction of the electric wire group  13  in the illustrated example, for example. In the damming part  15 , the bottom side surface of the trapezoidal cross-sectional shape is a seating surface  21 . The outer periphery shape part  19  of the damming part  15  is not limited thereto. 
     In the damming part  15 , the pair of side surfaces which face each other and interpose the seating surface  21  form electric wire through side surfaces  23 . The electric wire group  13  penetrates the damming part  15  from one electric wire through side surface  23  toward the other electric wire through side surface  23 . 
     As illustrated in  FIGS. 1A and 1B , burrs  17  in which molten resin which overhangs from the mold during the molding of the damming part  15  is solidified are formed between the electric wire through side surfaces  23  and the spaces between the adjacent electric wires  11 . As illustrated in  FIG. 2 , the burrs  17  are formed in the spaces between the respective electric wires  11  on the top surface side and the bottom surface side of the electric wire group  13 . 
     A low pressure injection molding machine  40 , which is described later, is used for the molding of the damming part  15  (refer to  FIG. 5 ). In the low pressure injection molding machine  40 , for example, general engineering plastics or general purpose plastics (polypropylene or the like) which are resin materials are used. In other words, the water entrance countermeasure structure of the wire harness of the present invention is formed by the electric wire group  13  being insert-molded into the resin material. 
     As illustrated in  FIG. 4 , the electric wire group insertion part  29  through which the electric wire group  13  is passed via the damming part  15  is provided in an integral case (a partition wall part)  25  of a water stop box  30 , for example. The electric wire group insertion part  29  is formed in a tubular shape which includes a trapezoidal through hole  31  in a front view. The outer periphery shape part  19  of the damming part  15  is formed so as to have a shape corresponding to the inner peripheral shape of the electric wire group insertion part  29 . In this case, the damming part  15  is fitted into the through hole  31  after one end side of the electric wire group  13  is inserted through the through hole  31 . In this case, the damming part  15  is formed to have the same sectional shape at an arbitrary position in the insertion direction. A water stop member  32  such as a seal sponge or rubber is bonded to the inner peripheral surface of the through hole  31 . 
     In the damming part  15 , the outer periphery shape part  19  may be formed on a tapered surface which is tapered in the insertion direction. Accordingly, it is possible to bring the damming part  15  into closer contact with the inner peripheral surface of the through hole  31  using an insertion pressure into the electric wire group insertion part  29 , and it is possible to obtain a high water stop property. 
     As illustrated in  FIG. 4 , for example, an electronic device (not illustrated) is housed in the integral case  25  of the water stop box  30 . A connector  27  which is connected to one end of the electric wire group  13  is connected to the electronic device. The connector  27  is housed in the integral case  25 , and the electric wire group  13  which is led out from the electric wire group insertion part  29  of the integral case  25  is subjected to a water entrance countermeasure by the damming part  15 . As a result, the connector  27  is housed in a case which is subjected to a water entrance countermeasure. 
     In this manner, the water stop box  30  which is provided with the water entrance countermeasure structure of the wire harness  100  according to the first exemplary embodiment is capable of suppressing a water entrance amount which infiltrates the water stop box from the outside of the case via the electric wire group insertion part  29  from which the electric wire group  13  is led out. 
       FIG. 5  is a perspective diagram of the low pressure injection molding machine  40 . 
     The low pressure injection molding machine  40  for integrally molding the damming part  15  in the electric wire group  13  is a molding machine which can be operated by even a single worker without external power such as an electric motor, and is configured to include a mold  46 , a mold clamping device (not illustrated), and the low pressure injection device  42  which pressurizes and injects molten resin into the mold  46 . 
     The low pressure injection device  42  includes a heating cylinder  44 , a plunger  33 , an injection cylinder  35 , a handle  37 , and a temperature controller  39 , and these are supported by a device support column  43  which is erected on a stand  41 . The heating cylinder  44  is provided with a heater for heating and melting a synthetic resin or the like, the plunger  33  injects molten resin in the heating cylinder from a nozzle (not illustrated), the injection cylinder  35  advances the plunger  33 , the handle  37  drives the injection cylinder  35 , and the temperature controller  39  keeps the heating temperature of the heating cylinder  44  at a desired temperature. 
     The low pressure injection molding machine  40  in the first exemplary embodiment refers to a device in which the amount of resin that can be molded in one injection molding is about 10 g at maximum, and during the mold clamping of the mold  46 , it is possible to manually perform using an air cylinder, a link, or the like. Naturally, the low pressure injection device  42  may drive the injection cylinder  35  using an external power such as an electric motor or air. More specifically, as the low pressure injection molding machine  40 , for example, it is possible to use a known “injection molding device” which is disclosed in JP-A-2010-260297, JP-A-2012-30429, and JP-A-2013-103492. 
     The mold  46  according to the first exemplary embodiment is disposed on the stand  41 . In the mold  46 , an upper mold  45  and a lower mold  47  are aligned to interpose, so as to house, the electric wire group  13  in deburring surfaces  49  (refer to  FIGS. 3 and 5 ) which are formed at both outside end parts along the extending direction of the electric wire group  13  so that a molding space which serves as a cavity capable of molding the damming part  15  is defined (a mold clamping step). 
     In other words, in the upper mold  45  and the lower mold  47 , harness housing parts  57  and  59  which include a cavity  51  and the deburring surfaces  49  are respectively formed on an upper mold divided surface (a divided surface)  53  and a lower mold divided surface (a divided surface)  55 . The cavity  51  is for molding the damming part  15 , and the deburring surfaces  49  are flat and interpose the outer periphery of the single row electric wire group  13  on both outside end parts of the cavity  51  which runs along the extending direction (the left-right direction in  FIG. 5 ) of the single row electric wire group  13 . The deburring surface  49  of the lower mold  47  has a recessed part capable of housing the single row electric wire group  13 , and the depth from the lower mold divided surface  55  is substantially the same as the diameter of the electric wire  11 . On the other hand, the deburring surface  49  of the upper mold  45  is formed in a flat plate shape on the same surface as the upper mold divided surface  53 . 
     Therefore, it is possible to mold clamp the upper mold  45  and the lower mold  47  in a state in which the single row electric wire group  13  is housed in the recessed part of the deburring surface  49  in the lower mold  47 , the electric wire group  13  is easily disposed in the harness housing part  59 , and electric wire biting during the mold clamping does not occur easily. 
     By supplying a molten resin (molten resin material)  67  from the supply path to the cavity  51  via a gate  63  (refer to  FIG. 3 ), the damming part  15  is molded to the outer periphery of the electric wire group  13 . 
     In the molding which uses the low pressure injection molding machine  40 , due to an amount of the molten resin  67  which is greater than the volume of the cavity  51  being injected into the cavity  51  of the mold  46  at a low pressure in a state in which the electric wire group  13  is interposed between the deburring surfaces  49  of the upper mold  45  and the lower mold  47 , a predetermined amount of the molten resin (a resin amount of the thermoplastic resin for molding the damming part  15 ) enters the cavity  51  and, as illustrated in  FIG. 3 , the excess part of the molten resin  67  protrudes from the gaps which are formed between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11  (an injection process). 
     However, the temperature of the molten resin  67  which is injected into the cavity  51  becomes lower toward the injection tip, the curing is promoted, and the mold temperature in the vicinity of the deburring surfaces  49  is less than or equal to the resin melting temperature of the thermoplastic resin. The molten resin  67  which is cured at the injection tip has its own sealing function. Since the low pressure injection device  42  low pressure injects the molten resin  67  into the cavity  51 , the molten resin  67  has fluidity, but a degree of fluidity at which the molten resin  67  passes through small gaps between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11  and a large amount leaks out is suppressed. 
     As a result, only an excess part of the molten resin with which the inside of the cavity  51  is filled protrudes slightly to form burrs  17  (refer to  FIGS. 1A and 1B ) without a large amount of the molten resin  67  leaking out from the gaps between the deburring surfaces  49  and the spaces between the adjacent electric wires  11 . 
     Here, the gaps between the electric wires  11  of the electric wire group  13  which is housed in the cavity  51  are larger than the gaps which are formed between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 . In other words, for example, in a case in which the electric wire  11  is a fine electric wire of 0.35 sq or less, the gaps (opening sectional area) which are formed between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11  are greatly smaller than the gaps between the electric wires  11  in the cavity  51 , and the flow resistance when the molten resin protrudes is large. Therefore, the molten resin  67  which is low pressure injected into the cavity  51  fills the cavity  51  and spreads through the gaps between the electric wires  11 , and subsequently only the excess part of the molten resin  67  protrudes from the gaps between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 . 
     Therefore, it is possible to assume that the gaps between the electric wires  11  in the cavity  51  are filled with the molten resin  67  due to the molten resin  67  protruding from the gaps between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 . In other words, by visually observing the burrs protruding from the gaps between the electric wire through side surface  23  and the spaces between the adjacent electric wires  11  in the damming part  15  which is molded, it is possible to confirm that the gaps between the electric wires  11  in the damming part  15  are filled with the resin material. 
     The mold  46  according to the first exemplary embodiment has a simple structure, and it is possible to reduce the manufacturing cost. Even if the position of the electric wire group  13  which is sandwiched by the deburring surfaces  49  of the upper mold  45  and the lower mold  47  changes a little in the width direction, since the gaps between the deburring surfaces  49  and the electric wire group  13  are sealed with the solidified molten resin, it is possible to flexibly cope with the position change of the electric wire group  13 . 
     Furthermore, a cooling mechanism (not illustrated) which cools the injection tip of the molten resin  67  which is injected into the cavity  51  may be provided in the vicinity of the deburring surfaces  49  in the mold  46 . A cooling mechanism is provided on the outside of the mold  46  corresponding to the deburring surfaces  49 , for example. Examples of the cooling mechanism include an air cooling system which uses cooling fins or a cold air blower, a water cooling system which works by providing water cooling pipes, electronic cooling which uses a Peltier element, and the like. The temperature at the injection tip of the molten resin  67  can be quickly lowered from an ordinary temperature using the cooling mechanism, and the curing of the molten resin  67  can locally be promoted. In this case, even if the electric wires  11  of the electric wire group  13  which is sandwiched by the deburring surfaces  49  are slightly separated from each other, it is possible to suppress the fluidity from an extent at which a large amount of the molten resin  67  leaks out from the gaps between the electric wires  11 , and thus, it is possible to mold the damming part  15  which is free from problems as a product. 
     In the first exemplary embodiment, the mold  46  is described as a horizontal split type; however, the mold  46  may be a vertical split type. 
     Next, the operations of the above configuration will be described. 
     In the water entrance countermeasure structure of the wire harness  100  according to the first exemplary embodiment, a part in the extending direction of the single row electric wire group  13  is surrounded to integrally mold the damming part  15 . 
     As illustrated in  FIG. 6A , the outer periphery shape part  19  of the damming part  15  is molded into a predetermined shape (a trapezoidal cross-sectional shape in the present exemplary embodiment) corresponding to the inner peripheral shape of the electric wire group insertion part  29 . In other words, the damming part  15  is formed in a free shape corresponding to the opening shape of the electric wire group insertion part  29 . 
     Since the plurality of electric wires  11  are linearly arranged in a single row in the diameter direction in the electric wire group  13 , as illustrated in  FIG. 6B , a resin unfilled space  70  which is surrounded by three or more of the electric wires  11  is not formed, and it is possible to reliably perform water entrance countermeasures between the adjacent electric wires  11 . 
     In the water entrance countermeasure structure of the wire harness  100  of the first exemplary embodiment, by selecting polypropylene which has excellent hinge characteristics as the resin material for molding the damming part  15 , the burrs  17  which protrude from the gaps do not easily bend and fall, and the burrs  17  do not scratch the electric wire coating, and do not fall to become foreign matter. 
     The damming part  15  is molded integrally with a low pressure injection molded resin material by the low pressure injection molding machine  40  which is different from an ordinary injection molding machine. In the molding by the low pressure injection molding machine  40 , the injection pressure of the molten resin  67  is low as compared with the ordinary injection molding machine. Therefore, it is possible to suppress the influence of heat on the electric wires  11  when molding the damming part  15 . The molding by the low pressure injection molding machine  40  can reduce the scale of the equipment as compared with an ordinary injection molding machine. 
     In this manner, according to the manufacturing method of the wire harness of the first exemplary embodiment, the single row electric wire group  13  is disposed in the harness housing parts  57  and  59 , and when mold clamping the upper mold  45  and the lower mold  47  which are aligned so as to interpose the single row electric wire group  13  in parallel with the flat deburring surfaces  49  which are formed on both outside end parts of the cavity  51  which runs along the extending direction of the electric wire group  13 , a molding space for molding the damming part  15  is defined between the upper mold  45  and the lower mold  47 . 
     With the gaps which are formed between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11  remaining vacant, a greater amount of the molten resin  67  than the volume of the cavity  51  is injected at low pressure into the cavity  51 . As a result, the excess part of the molten resin  67  with which the cavity  51  is filled protrudes from the gaps between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 . Here, since the gaps between the electric wires  11  in the cavity  51  are larger than the gaps which are formed between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 , it is possible to assume that the gaps between the electric wires  11  in the cavity  51  are filled with the molten resin  67  due to the molten resin  67  protruding from the gaps between the flat deburring surfaces  49  and the spaces between the adjacent electric wires  11 . 
     In other words, by visually observing the burrs  17  protruding from the gaps between the electric wire through side surface  23  and the spaces between the adjacent electric wires  11  in the damming part  15  which is molded, it is possible to confirm that the gaps between the electric wires  11  in the damming part  15  are filled with the resin material. 
     The exemplary embodiment of the damming part according to the present invention is not limited to the damming part  15  in the first exemplary embodiment, and may adopt various forms. 
     For example, as illustrated in  FIG. 7A , a damming part  15 A according to the second exemplary embodiment of the present invention includes the outer periphery shape part  19  which surrounds a part of three rows of electric wire groups  13   a ,  13   b , and  13   c  in the extending direction, and according to the inner peripheral shape of the electric wire group insertion part  29 . The three rows of electric wire groups  13   a ,  13   b , and  13   c  are disposed to be separated by a predetermined interval in the lining up direction of the electric wires  11 . 
     As illustrated in  FIG. 7B , in the damming part  15 A, a substantially trapezoidal lightening part  24  is recessed in the seating surface  21 . The lightening part  24  is formed in the thick part on the side of the seating surface  21  in the damming part  15 A, thereby reducing the volume of the thick part and preventing molding defects such as sink marks and voids. Furthermore, in the lightening part  24 , lightening recessed parts  24   a  having a predetermined width are formed so as to be positioned between the rows of electric wire groups  13   a ,  13   b , and  13   c.    
     When the damming part  15 A is molded, the lightening part  24  is formed in the seating surface  21  of the damming part  15 A by a substantially trapezoidal lightening molding part (not illustrated) which project from the lower mold  47  of the mold  46  (refer to  FIG. 4 ). In other words, when integrally molding the damming part  15 A, when the upper mold  45  and the lower mold  47  are mold clamped in a state in which the three rows of the electric wire groups  13   a ,  13   b , and  13   c  are separated by a predetermined interval and housed in the recessed part of the deburring surfaces  49  in the lower mold  47 , the lightening molding part for molding the lightening recessed part  24   a  is positioned between each of the rows of the electric wire groups  13   a ,  13   b , and  13   c  in the cavity  51 . 
     Therefore, even if the electric wires  11  flex under the resin pressure of the molten resin  67  which is supplied into the cavity  51 , a minimum necessary interval S between each row of the electric wire groups  13   a ,  13   b , and  13   c  is secured by the lightening molding part of the lower mold  47  as illustrated in  FIG. 7C . 
     Therefore, in a case in which it is necessary to provide a predetermined interval between the plurality of electric wire groups  13   a ,  13   b , and  13   c  which penetrate the integral case, even if the distance between the electric wire groups  13   a ,  13   b , and  13   c  is taken into account in the tolerance, by setting the predetermined width of the lightening recessed part  24   a  in the damming part  15 A so as to satisfy the necessary dimensions for the interval, even in a worst case for tolerance, it is possible to secure an interval between the electric wire groups  13   a ,  13   b , and  13   c  which are buried in the damming part  15 A to a level greater than or equal to the necessary distance. The guarantee of the interval between the electric wire groups  13   a ,  13   b , and  13   c  can be discerned only by visual observation as to whether or not the electric wires  11  are exposed on the resin surface of the lightening part  24 . 
     In a case of a conventional structure in which a plurality of electric wire groups are respectively arranged into a plurality of separate electric wire bundles which are conformed to the water stop member, and subsequently the respective electric wire bundles are passed through the integral case at predetermined intervals, it is necessary to form a plurality of through holes to penetrate the integral case. Conversely, in a case in which the damming part  15 A of the second exemplary embodiment is used, one through hole  31  may be formed in the integral case  25 , and the degree of freedom in designing the integral case is improved. In the damming part  15 A, since the plurality of electric wire groups  13   a ,  13   b , and  13   c  are buried in the damming part  15 A by a single molding, it is possible to obtain a water entrance countermeasure structure. 
     Furthermore, even in a case in which it is necessary to float the plurality of electric wire groups  13   a ,  13   b , and  13   c  with respect to a vehicle body frame or the like to which the integral case  25  is fixed, since the damming part  15 A which includes the lightening part  24  in the seating surface  21  has a high degree of freedom in the dimension of the height direction, it is possible to easily adapt. 
       FIG. 8  is an exploded perspective diagram of the main parts representing a device connection structure which is provided with a water entrance countermeasure structure of a wire harness according to the third exemplary embodiment of the present invention. 
     A wire harness  200  which is provided with the water entrance countermeasure structure of the wire harness according to the third exemplary embodiment includes electric wire groups  113   a  and  113   b  which are formed of the plurality of electric wires  11  which are provided to line up in the horizontal direction, a damming part  15 B made of a resin material, and a water stop member  115 . The electric wire groups  113   a  and  113   b  are disposed in two stages. 
     As illustrated in  FIGS. 9A and 9B , the damming part  15 B includes an outer periphery shape part  19 B which has a trapezoidal cross section taken along a plane which is orthogonal to the extending direction of the electric wire groups  113   a  and  113   b . In the damming part  15 B, the bottom side surface of the trapezoidal cross-sectional shape is the seating surface  21 , and the pair of side surfaces which face each other and interpose the seating surface  21  form the electric wire through side surfaces  23 . The electric wire groups  113   a  and  113   b  penetrate the damming part  15 B from one electric wire through side surface  23  toward the other electric wire through side surface  23 . 
     Furthermore, the damming part  15 B includes a thin lip piece  150  extending along a pair of sides which extend in the respective extending directions of the electric wire groups  113   a  and  113   b  from a pair of acute-angled parts of the substantially trapezoidal cross-sectional shape of the outer periphery shape part  19 B. 
     The trapezoidal cross-sectional shape of the damming part  15 B according to a trapezoidal through hole  129  in the electric wire group insertion part  127  which is illustrated in  FIG. 9B . The electric wire group insertion part  127  has a divided structure which is provided in a top case (a partition wall part)  133  and a bottom case (a partition wall part)  135  of a water stop box  131 . The damming part  15 B of the wire harness  200  is fitted into the electric wire group insertion part  127 . In other words, the wire harness  200  penetrates the partition wall part due to the damming part  15 B which is fitted into the electric wire group insertion part  127 . 
     The electric wire group insertion part  127  is formed by combining a bottom plate part  137  which is formed on the bottom case  135  and an angular rim part  139  which is formed on the top case  133  to form a tubular shape in which the trapezoidal through hole  129  is defined. In this case, the damming part  15 B is interposed and fixed by the bottom plate part  137  and the angular rim part  139  by being placed on the bottom plate part  137  and subsequently being covered by the angular rim part  139 . The interposing of the damming part  15 B is performed by fixing with a fastener (not illustrated) which fastens the divided top case  133  and bottom case  135 , or by fixing a fastener (not illustrated) which directly fastens the bottom plate part  137  and angular rim part  139 . 
     The top case  133  and the bottom case  135  house an electronic device (not illustrated). In the wire harness  200 , for example, connectors  141  which are provided in each of the two electric wire groups  113   a  and  113   b  are connected to the electronic device. The water stop box  131  is subjected to water stop countermeasures using the damming part  15 B due to the damming part  15 B being interposed by the electric wire group insertion part  127  in a state in which the electric wire groups  113   a  and  113   b  overlap each other vertically separated into two levels. 
     In the electric wire group insertion part  127 , the water stop member  115  such as a seal sponge or rubber is bonded to the inner peripheral surface of the through hole  129 . The water stop member  115  reliably water stops the space between the inner peripheral surface of the through hole  129  and the outer periphery shape part  19 B of the damming part  15 B. It is also possible to bond the water stop member  115  to the outer periphery shape part  19 B of the damming part  15 B. 
     At this time, as illustrated in  FIG. 9C , the pair of water stop members  115  are overlapped along the lip piece  150  of the damming part  15 B. Since the tip of this lip piece  150  is extremely thin and can be deformed so as to balance both sides by the pressure of the water stop members  115  from above and below, it becomes possible for the water stop members  115  to intersect in a state in which there is little change in the compression ratio of the water stop members  115  at a location at which the top and bottom water stop members  115  intersect. Therefore, the water stop member  115  is capable of reliably water stopping the space between the inner peripheral surface of the through hole  129  and the outer periphery shape part  19 B. 
     It is possible to form the lip piece  150  by using parting lines of the upper mold  45  and the lower mold  47  which define the cavity  51  for molding the damming part  15 B (refer to  FIG. 5 ). Therefore, it becomes unnecessary to be concerned with mold shifting and mold alignment, and the mold  46  is easy to process. 
       FIG. 10A  is a perspective diagram illustrating a damming part  15 C which is a modification example of the damming part  15 B,  FIG. 10B  is a lateral sectional diagram of a state in which the damming part  15 C illustrated in  FIG. 10A  is fitted into the through hole of an electric wire group insertion part  127 C, and  FIG. 10C  is an enlarged diagram of the D part in  FIG. 10B . 
     As illustrated in  FIGS. 10A and 10B , the damming part  15 C includes an outer periphery shape part  19 C which has a flat hexagonal cross section taken along a plane which is orthogonal to the extending direction of the electric wire groups  113   a  and  113   b . In the damming part  15 C, both side surfaces which interpose the outer periphery shape part  19 C form the electric wire through side surface  23 . The electric wire groups  113   a  and  113   b  penetrate the damming part  15 B from one electric wire through side surface  23  toward the other electric wire through side surface  23 . 
     Furthermore, the damming part  15 C includes the thin lip piece  150  extending along a pair of sides which extend in the respective extending directions of the electric wire groups  113   a  and  113   b  from a pair of acute-angled parts of the flat hexagonal cross-sectional shape of the outer periphery shape part  19 C. 
     In the electric wire group insertion part  127 C, the water stop member  115  is bonded to the inner peripheral surface of the through hole, and the water stop member  115  reliably water stops the space between the inner peripheral surface of the through hole and the outer periphery shape part  19 C of the damming part  15 C. 
     As illustrated in  FIG. 10C , the pair of water stop members  115  are overlapped along the lip piece  150  of the damming part  15 C. Since the tip of this lip piece  150  is extremely thin and can be deformed so as to balance both sides by the pressure of the water stop members  115  from above and below, it becomes possible for the water stop members  115  to intersect in a state in which there is little change in the compression ratio of the water stop members  115  at a location at which the top and bottom water stop members  115  intersect. Therefore, the water stop member  115  reliably water stops the space between the inner peripheral surface of the through hole and the outer periphery shape part  19 C of the damming part  15 C in the electric wire group insertion part  127 C. 
       FIG. 11A  is a perspective diagram of a damming part  15 D according to the fourth exemplary embodiment of the present invention as viewed from a seating surface side, and  FIG. 11B  is a perspective diagram of a damming part  15 E of a modification example of the damming part  15 D illustrated in  FIG. 11A  as viewed from the seating surface side. 
     As illustrated in  FIG. 11A , the damming part  15 D according to the fourth exemplary embodiment includes an outer periphery shape part  19 D which has a trapezoidal cross section taken along a plane which is orthogonal to the extending direction of the electric wire groups  13   a ,  13   b , and  13   c . In the damming part  15 D, the bottom side surface of the trapezoidal cross-sectional shape is the seating surface  21 . In the damming part  15 D, the pair of side surfaces which face each other and interpose the seating surface  21  form electric wire through side surfaces  23 . The electric wire groups  13   a ,  13   b , and  13   c  penetrate the damming part  15 D from one electric wire through side surface  23  toward the other electric wire through side surface  23 . 
     In the damming part  15 D of the fourth embodiment, the vicinity of a pair of edge parts  26  along the extending direction of the electric wire groups  13   a ,  13   b , and  13   c  in the outer periphery shape part  19 D, and two locations of the intermediate part between the pair of edge parts  26  are each formed in a trapezoidal cross-sectional shape as a part of the outer periphery shape part  19 D. The pair of edge parts  26  are trapezoidal body corner parts at which an annular surface (an annular outer peripheral surface which is interposed between the pair of electric wire through side surfaces  23 ) of the outer periphery shape part  19 D intersects each of the a pair of electric wire through side surfaces  23  which are penetrated by the electric wire groups  13   a ,  13   b , and  13   c.    
     The other parts in the outer periphery shape part  19 D have a cross-sectional shape in which a plurality of recessed parts are formed in the bottom side of the trapezoidal cross-sectional shape. In other words, a plurality of lightening parts  24 D in which a plurality of rectangular parallelepiped spaces which are linearly arranged in three rows along the edge parts  26  in the lining up direction of the electric wires  11  are recessed is formed in the seating surface  21  of the damming part  15 D. 
     Therefore, in the mold which molds the damming part  15 D, a thin pin-shaped lightening molded part for creating the lightening part  24 D protrudes toward the cavity. Here, since the damming part  15 D is molded using low pressure injection, there is no concern of thin pin-shaped lightening molded part deforming and breaking under the resin pressure of the molten resin. 
     In a damming part  15 E illustrated in  FIG. 11B , of the vicinity of the pair of edge parts  26  along the extending direction of the electric wire groups  13   a ,  13   b , and  13   c  in an outer periphery shape part  19 E, and two locations the intermediate part between the pair of edge parts  26  are each formed in a trapezoidal cross-sectional shape as a part of the outer periphery shape part  19 E. 
     The other parts in the outer periphery shape part  19 E have a cross-sectional shape in which a plurality of recessed parts are formed in the bottom side of the trapezoidal cross-sectional shape. In other words, a plurality of lightening parts  24 E in which a plurality of rectangular parallelepiped spaces which are linearly arranged in three rows along the edge parts  26  in the lining up direction of the electric wires  11  are recessed in a staggered formation is formed in the seating surface  21  of the damming part  15 E. 
     According to the damming part  15 D ( 15 E) according to the fourth embodiment, when the damming part  15 D ( 15 E) is set in the electric wire group insertion part  127  of the water stop box  131  illustrated in  FIG. 8 , for example, entrance of water from between the damming part  15 D ( 15 E) and the through hole  129  of the electric wire group insertion part  127  is suppressed by the outer periphery shape part  19 D ( 19 E) in the vicinity of the pair of edge parts  26  which are formed in the trapezoidal cross-sectional shape, and the two locations of the intermediate part between a pair of edge parts  26 . 
     In the damming part  15 D ( 15 E), by reducing the volume of the thick part due to the plurality of lightening parts  24 D ( 24 E) being formed in the other parts of the outer periphery shape part  19 D ( 19 E), molding defects such as sink marks and warping arise less easily during the molding of the electric wire groups  13   a ,  13   b , and  13   c.    
     Therefore, for example, even in a case in which it is necessary to float the plurality of electric wire groups  13   a ,  13   b , and  13   c  with respect to a vehicle body frame or the like to which the water stop box  131  is fixed, in the damming part  15 D ( 15 E) which includes the lightening part  24 D ( 24 E) in the seating surface  21 , since molding defects such as sink marks and warping do not occur easily, it is possible to increase the dimension of the height direction. 
     In other words, in a damming part  215  of the comparative example illustrated in  FIG. 12A , the vicinity of a pair of edge parts  226  along the extending direction of the electric wire groups  13   a ,  13   b , and  13   c  in an outer periphery shape part  251 , and two locations of the intermediate part between the pair of edge parts  226  are each formed in a trapezoidal cross-sectional shape as a part of the outer periphery shape part  251 . Three lightening parts  224  in which three deep groove spaces which are linearly arranged in three rows along the edge parts  226  in the lining up direction of the electric wires  11  are recessed is formed in a seating surface  221  of the damming part  215 . 
     In this case, as illustrated in  FIGS. 12B and 12C , deformation due to warping occurs in electric wire through side surfaces  223  and the outer periphery shape part  251  of the damming part  215 . Therefore, the outer periphery shape part  251  can not evenly compress the water stop member  115  of the electric wire group insertion part  127 , and the water stop member  115  reliably water stops the space between the inner peripheral surface of the through hole  129  and the outer periphery shape part  251 . There is a concern that the electric wires  11  and the damming part  215  will be peeled off due to depression caused by warping which occurs in the electric wire through side surface  223  of the damming part  215 . 
       FIG. 13A  is a perspective diagram of a damming part  15 F according to the fifth exemplary embodiment of the present invention, and  FIG. 13B  is a sectional diagram of a state in which the damming part  15 F illustrated in  FIG. 13A  is fitted into the through hole  129  of the electric wire group insertion part  127  taken along an XIII-XIII line. 
     As illustrated in  FIG. 13A , the damming part  15 F includes an outer periphery shape part  19 F which surrounds a part of three rows of electric wire groups  13   a ,  13   b , and  13   c  in the extending direction, and according to the inner peripheral shape of the electric wire group insertion part  127 . The outer periphery shape part  19 F includes a pair of annular grooves  20  which extend in the peripheral direction. In other words, as illustrated in  FIG. 13B , the outer periphery shape part  19 F is formed in a cross-sectional waveform shape along the extending direction of the electric wire groups  13   a ,  13   b , and  13   c.    
     According to the damming part  15 F according to the fifth exemplary embodiment, for example, when the damming part  15 F is set in the electric wire group insertion part  127  of the water stop box  131  illustrated in  FIG. 8 , the length of a parallel surface of the outer periphery shape part  19 F which includes the annular grooves  20  which is parallel to the extending direction of the electric wire groups  13   a ,  13   b , and  13   c  with respect to the water stop member  115  is increased. Therefore, time for which the entrance of water from between the damming part  15 F and the through hole  129  of the electric wire group insertion part  127  can be tolerated increases, and it is possible to achieve a favorable effect on the water entrance countermeasure. 
     Since the annular grooves  20  which are formed in the outer periphery shape part  19 F serve as a lightening part in the thick part of the damming part  15 F, in the damming part  15 F, molding defects such as sink marks and voids arise less easily during the molding of the electric wire groups  13   a ,  13   b , and  13   c.    
     Here, the characteristics of the exemplary embodiments of the manufacturing method of the wire harness according to the present invention described above are briefly summarized and listed as the following [1] to [2]. 
     [1] A manufacturing method of a wire harness which includes at least one bundle of an electric wire group ( 13 ) in which a plurality of electric wires ( 11 ) are linearly arranged, and a damming part ( 15 ) made of a resin material, wherein the damming part surrounds a part of the electric wire group in an extending direction of the electric wire group, and wherein the damming part includes an outer periphery shape part ( 19 ) according to an inner peripheral shape of an electric wire group insertion part ( 29 ), the manufacturing method comprising: 
     disposing a part of the one bundle of the electric wire group in a harness housing part ( 57  and  59 ) and mold clamping an upper mold ( 45 ) and a lower mold ( 47 ) in which the harness housing part is formed on a pair of divided surfaces (the upper mold divided surface  53  and the lower mold divided surface  55 ); and 
     performing low pressure injection of a larger amount of molten resin (the molten resin  67 ) than a volume of a cavity ( 51 ) into the cavity, so that the resin material with which the cavity is filled protrudes from gaps between flat deburring surfaces ( 49 ) and adjacent electric wires, 
     wherein the harness housing part includes the cavity so as to mold the damming part and includes the flat deburring surfaces which clamp an outer periphery of the one bundle of the electric wire group at both outside end parts of the cavity which face each other in the extending direction of the electric wire group. 
     [2] The manufacturing method of the wire harness according to the above-described [1], 
     wherein the resin material includes polypropylene. 
     The present invention is not limited to the exemplary embodiments described above, and various modifications, improvements, and the like thereto are possible. In addition, the materials, shapes, dimensions, numbers, disposition locations, and the like of the constituent elements in the above-described exemplary embodiments are arbitrary as long as the present invention can be achieved, and are not limited. 
     DESCRIPTION OF REFERENCE NUMERALS AND SIGNS 
       11  . . . electric wire,  13  . . . electric wire group,  15  . . . damming part,  19  . . . outer periphery shape part,  29  . . . electric wire group insertion part,  45  . . . upper mold,  47  . . . lower mold,  49  . . . deburring surface,  51  . . . cavity,  53  . . . upper mold divided surface (divided surface),  55  . . . lower mold divided surface (divided surface),  57  . . . harness housing part,  59  . . . harness housing part,  67  . . . molten resin (molten resin material).