Abstract:
A connector housing includes a plurality of terminal chambers into for respectively accommodating a terminal provided with an electric wire. A mat-shaped rubber plug is attached to a rear end portion of the connector housing. In the rubber plug, recessed portions are formed so as to remain cylindrical protrusions each having a through hole through which the electric wire is inserted. A rear holder is attached to the rear end portion of the connector housing to retain the rubber plug thereat. The rear holder includes projections each configured so as to compress the associated protrusion of the rubber plug in the diameter direction of the electric wire as being inserted into the associated recessed portion of the rubber plug. The rubber plug includes at least one protrusion block formed by integrating adjacent cylindrical protrusions.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a waterproof connector used for the connection of wire harness mounted in a vehicle, and relates to a waterproof plug used for sealing the inside of the connector while being held between the housing of the waterproof connector and an electric wire of the wire harness. 
     For a related waterproof connector, at the least, the portion whereat male and female terminals engage with each other must be enclosed within in a waterproof space. However, for a waterproof connector having as a function the electrical detection of the engagement of connectors, a terminal that acts in response to the movement of a locking mechanism is provided inside a connector housing, so that the locking mechanism is also enclosed in a waterproof space. For even if a waterproof connector does not have an engagement detector, when it is employed under adverse conditions, mud or dust may become attached to its locking mechanism and prevent the locking mechanism from being easily released. Thus, for such a waterproof connector, the enclosure of the locking mechanism in a waterproof space is also effective. 
     However, when a locking mechanism is accommodated inside a waterproof space, a problem also arises concerning the time required to unlock it. That is, since release of the locking mechanism must be affected from outside a waterproof seal that defines the waterproof space, some countermeasure is required that will permit the mechanism to be unlocked under these conditions. 
     Waterproof connectors with engagement detectors for which such countermeasures are provided are disclosed in Japanese Patent Publications Nos. 9-106852A and 10-270118A. 
     FIG. 19 is a cross-sectional view of the waterproof connector disclosed in the former publication. In a rear wall of a female connector housing  1   a  through hole  1   b  is formed through which is passed a lock arm  1   d  in which, at its distal end, an engagement hole  1   c  is formed. To enable the lock arm  1   d  to be flexibly inclined, it also penetrates and is supported by a waterproof seal  2  that is fitted into the through hole  1   b . Riding on the upper portion of the lock arm  1   d  is an arm responsive terminal  3  that urges the lock arm  1   d  down towards a projection  4   a , formed inside a male connector housing  3  on whose upper face a protrusion  4   b  and two engagement detection terminals  5  are provided. 
     When the male connector housing  4  is fitted into the female connector housing  1 , its distal end closely contacts the outer face of a waterproof seal  6  located in a portion into which the lock arm  1   d  is projected, a tightly closed waterproof space S that is defined by the waterproof seal  2 . When the connector housings  1  and  4  are normally engaged, the protrusion  4   b  is fitted into the engagement hole  1   c  in the lock arm  1   d , while the arm responsive terminal  3  contacts the engagement detection terminals  5  and the engagement state is detected by an external circuit. 
     To release the lock, the lock arm  1   d  is tilted to the position shown in FIG. 19 by the exertion of a force outside the waterproof space S, i.e., by pushing an external end  1   e  of the lock arm  1   d  that extends outward from the waterproof seal  2 . Then, the protrusion  4   b  is disengaged from the hole  1   c  of the lock arm  1   d , and the connector housings  1  and  4  can be separated, releasing the lock. In this unlocking process, the waterproof seal  2  that defines the portion into which the lock arm  1   d  is inserted permits the tilting of the lock arm  1   d.    
     FIG. 20 is a cross-sectional view of a waterproof connector disclosed in the latter publication. In the waterproof connector, a female connector housing  7 A comprises: a flexible lock arm  7   c , which engages a male connector housing  7 B when the two connector housings  7 A and  7 B are normally engaged; and a short-circuit terminal  8 A that interacts with the bending of the lock arm  7   c . The male connector housing  7 B comprises a detection terminal  8 B, which interacts with the recovery of the lock arm  7   c  when the connector housings  7 A and  7 B are normally engaged, and contacts the short-circuit terminal  8 A. 
     A seal cover  9 , which permits the bending of the lock arm  7   c  and covers its distal end and the short-circuit terminal  8 A, is attached to the connector housing  7 A. The lock arm  7   c  and the terminals BA and BB are accommodated in the waterproof space S that is defined by the seal cover  9 . 
     The waterproof connectors shown in FIGS. 19 and 20 have the following problem, though the release of the lock arms  1   d  and  7   c  can be performed from the outside of the waterproof seal  2  and the seal cover  9 . 
     Since the waterproof connector in FIG. 19 is to be unlocked by pushing the external end  1   e  of the lock arm  1   d  and by tilting the lock arm  1   d , the through hole of the waterproof seal  2  must be formed to permit the lock arm  1   d  to be tilted. Therefore, water tends to enter through the penetrating portion. Especially when the penetrating portion is composed of elastic material that will permit tilting, the contact force exerted against the lock arm by the waterproof seal  2  is reduced, and the sealing performance is deteriorated. 
     For the waterproof connector in FIG. 20, the lock arm  7   c  must be operated through the seal cover  9 , so that the operation of the unlocking mechanism is not ideal. 
     Waterproof connectors are structured to waterproof electric wires connected to the respective terminals inserted by fitting a seal member to each electric wire so as to prevent the entry of water and the like from the outside. Otherwise, a plurality of mat-like seal members are integrally formed with electric wire sealing portions to waterproof the whole electric wire by fitting the mat-like seal members to the rear part of a connector housing. The former seal member is called a separate-type waterproof plug, whereas the latter one is called a mat-type waterproof plug. 
     Japanese Utility Model Publication No. 62-201480U discloses the former separate-type waterproof plug, which will be described with reference to FIG.  21 . 
     The waterproof plug  61  has an insertion hole  62  for receiving an electric wire W and a cylindrical wall  63  surrounding the insertion hole  62 . More specifically, the central hole is used as the insertion hole  62 , and the peripheral wall is used as the cylindrical wall  63  in order to form an independent tubular body. 
     The waterproof plug  61  of this kind is normally formed of rubber material such as silicone rubber and NBR, and is formed by rapping molds with the direction of passing the insertion hole  62  therethrough as a rapping direction. Annular convex portions  64  and  65  are also formed on both outer and inner peripheral faces of the cylindrical wall  63  along a peripheral direction crossing the rapping direction. 
     As shown in FIG. 22, these annular convex portions  64  and  65  are used to make the waterproof plug  61  stick fast to the inner peripheral wall of the insertion hole  67  of a connector housing  66  and to the outer periphery of the electric wire W when the waterproof plug  61  is held between the inner peripheral wall of the insertion hole  67  and the outer periphery of the electric wire W. 
     However, an excessive force tends to become applied to the related waterproof plug  61  at the time of rapping the product because the annular convex portions  64  and  65  are provided on both the inner and outer peripheral faces of the cylindrical wall  63 . 
     Therefore, though no serious problem arises when rubber material having a high elastic stress marginal value is employed as before, the use of thermoplastic elastomeric resin (e.g., TPEE) having an elastic stress marginal value lower than that of the rubber material may easily make the product undergo plastic deformation at the time of mold opening, thus resulting in poor dimensional stability. 
     FIG. 23 is a diagram showing a related waterproof connector disclosed in Japanese Patent Publication No. 343972A, and FIGS. 24A and 24B are diagrams showing a mat-type rubber plug used for the waterproof connector. In FIG. 23, the waterproof connector, which engages another connector, comprises: a male connector housing  71 ; female terminals  72 , retained in a terminal chamber; and a mat-shaped rubber plug  74 , so mounted that it close the rear end opening of the connector housing  71 . 
     Formed in the rubber plug  74  are a plurality of insertion holes  75  through which electric wires  73  are passed that extend to the rear to the female terminals  72 . As is shown in FIGS. 13A and 13B, cylindrical walls  76  define the respective through holes  75 , and an appropriate flexible force exerted by the cylindrical walls  76  closely attaches them to the outer faces of the electric wires  73  that are passed through the through holes  75 . An ensured gap  77 , described around the cylindrical walls  76 , permits the cylindrical walls  76  to freely expand when the electric wires  73  are passed through the through holes  75  to the female terminals  72 . 
     To fabricate the rubber plug  74  of the related waterproof connector, the cylindrical walls  76  are formed separately, and the ensured space  77 , which permits the expansion of the cylindrical walls  76 , is described obtained around their periphery. Therefore, since the cylindrical walls  76  can expand freely, the terminals  72  can easily be passed through the through holes  75 . However, the strength of the seals that are obtained after the terminals  72  have been inserted depends only the flexibility of the independent cylindrical walls  76 , since no member is provided to increase their sealing strength. 
     Further, since the through holes  75  are defined by the independent cylindrical walls  76 , as is shown in FIG. 24B, a pitch P must be set for the through holes  75 , while for the cylindrical walls  76  a satisfactory thickness H 1  and an adequate intervening space H 2 , in the gap  77  a round the periphery of the cylindrical walls  76 , are ensured. As a result, the pitch P is increased, and accordingly, the size of the connector is increased. 
     SUMMARY OF THE INVENTION 
     While taking the above problems into account, it is the first objective of the present invention to provide a waterproof connector having a superior sealing function and a preferable unlocking function. 
     It is the second objective of the present invention to provide a waterproof connector that is compactly made and that provides an improved sealing function. 
     It is the third objective of the present invention to provide a waterproof plug capable of making plastic deformation hardly producible at the time of rapping and also increasing dimensional stability even in a case where any material having a lower elastic stress marginal value, for example, thermoplastic elastomeric resin is used to form the waterproof plug. 
     In order to achieve the first object, according to the present invention, there is provided a waterproof connector comprising: 
     a pair of connector housings to be engaged with each other; 
     a lock member for locking the connector housings at a position where the connector housings are completely engaged; 
     a seal member for defining a waterproof space which accommodates the lock member, the seal member having a through hole which communicates inside and out of the waterproof space; and 
     an unlock member sealedly inserted into the through hole so as to be slidable in an insertion direction thereof to unlock the engagement of the housing. 
     In this configuration, when the unlock member merely slides in the direction in which the waterproof seal is penetrated, the release of the lock member can be affected from outside the waterproof seal. In this case, since the unlock member need only slide in the inserting direction, unlike in the related case wherein tilting is permitted, water is prevented from entering via the through hole in the seal member. Further, since the through hole of the seal member need not be composed of elastic material that will permit tilting, the con tact force exerted by the seal member on the unlock member can be increased, and accordingly, the sealing function enhanced. In addition, since the lock member is moved directly by the unlock member, a precise operation can be easily implemented, unlike the related case: where the lock member is controlled via the seal member. 
     Preferably, one of the connector housings includes a guide member situated adjacent to the seal member for guiding the slide movement of the unlock member. The seal member is made of a material harder than that of the seal member. 
     In this configuration, since the guide member along which the unlock member slides is provided for the less elastic member that is adjacent to the seal member, the unlock member can be moved linearly and stably. Thus, the lock member can be precisely and easily released, without compromising the integrity of the seal member. 
     Preferably, one of the connector housings includes a through hole situated adjacent to the seal member. The seal member includes a cylindrical wall portion surrounding the through hole and fitted with the through hole of the connector housing. The cylindrical wall portion is compressed bet ween an outer periphery of the unlock member and an inner wall of the through hole of the connector housing. 
     In this configuration the cylindrical wall portion around the through hole of the seal member is compresses by insertion of the unlock member, so that the contact force exerted by the seal member on the connector housing and the unlock member is increased. Therefore, the seal at the portion whereat the unlock member is inserted penetrates can be even more increased. 
     Preferably, the lack member is a lock arm provided with one of the connector housings, which is flexible between a first position for locking the engagement of the connector housings and a second position for unlocking the engagement. The unlock member slides in the through hole toward inside of the waterproof space to flex the lock arm towards the second position. 
     In this configuration, since the unlock member slides and flexes the lock arm, the connectors can be unlocked. 
     Preferably, the sliding direction of the unlock member and the flexing direction of the lock arm is substantially orthogonal. The lock arm is provided with a slant face for converting the sliding movement of the unlock member into the flexing movement of the lock arm, and converting a restoring movement of the lock arm into a slide-back movement of the unlock member. 
     In this configuration, since the unlock member be slid so that it pushes against the slant face of the lock arm, the lock arm can be flexed until it is perpendicular to the direction in which the unlock member is slid. Therefore, when the lock arm is so formed that it can be freely flexed vertically, the unlock member can be set so it can be slid forward and backward, and when the unlock member is slid from the rear of the connector housing to the front, the lock arm can be released. Further, when the flexed lock arm is to be returned to its original position, the slant face of the lock arm pushes the unlock member in the sliding direction, so that in particular, members such as a spring for urging the unlock member backward need not be provided. 
     Preferably, the waterproof connector further comprises a terminal for electrically detecting the engagement condition of the connector housings, which is disposed inside of the waterproof space. 
     In this configuration, since the terminal formed in the waterproof space interact with the lock member accommodated within the same waterproof space, the terminal can be brought into contact or separated in accordance with the action of the lock member, and the engagement state of the connectors can be obtained by electrically detecting the state of the terminal. 
     Preferably, a distal end of the unlock member, which abuts against the slant face of the lock arm, is rounded for 
     In this configuration, since the distal end of the unlock member is rounded, there is minimal contact between the distal end and the slant face and the sliding movement of the unlock member can be precisely converted into the flexing movement of the lock arm. 
     Preferably, the slant face includes a groove portion for receiving the distal end of the unlock member. 
     In this configuration, the distal end of the unlock member always appropriately abuts against the slant face of the lock arm, and does not slide off therefrom. 
     In order to achieve the second object, according to the present invention, there is provided a waterproof connector comprising: 
     a connector housing including a plurality of terminal chambers into for respectively accommodating a terminal provided with an electric wire; 
     a mat-shaped rubber plug attached to a rear end portion of the connector housing, in which recessed portions are formed so as to remain cylindrical protrusions each having a through hole through which the electric wire is inserted; and 
     a rear holder attached to the rear end portion of the connector housing to retain the rubber plug thereat, the rear holder, including projections each configured so as to compress the associated protrusion of the rubber plug in the diameter direction of the electric wire as being inserted into the associated recessed portion of the rubber plug, 
     wherein the rubber plug includes at least one protrusion block formed by integrating adjacent cylindrical protrusions. 
     In this case, since the adjacent cylindrical protrusions are formed as integrated blocks, and unlike the related art, do not separately define a gap in the vicinity, the pitch between the through holes can be reduced, so that a compact connector can be made. 
     Preferably, the waterproof connector further comprises: 
     a provisional retaining member for provisionally retaining the rear holder onto the connector housing such that the projections of the rear holder does not interfere with the associated protrusions of the rubber plug; and 
     a retaining member for securely retaining the rear holder onto the connector housing such that the projections interferes the associated projections. 
     The electric wires are inserted into the associated through holes of the rubber plug when the rear holder is provisionally retained onto the connector housing. Then the rear holder is securely retained onto the connector housing while compressing the protrusions of the rubber plug by the projections of the rear holder. 
     In this case, since the rear holder can be temporarily held on the connector housing before the projections of the rear holder are pressed into the recessed portion in the rubber plug, the protrusions in the rubber plug are permitted to expand freely, so that the efficiency of the operation when the terminals are inserted can be improved without the rear holder having to be held in place by hand. Further, since the rear holder can be securely held on the connector housing after the projections of the rear holder have been pressed into the recessed portion of the rubber plug, the state where the rubber plug and the electric wires more closely contact each other can be stably maintained for an extended period of time, and the reliability of the sealing can be enhanced. 
     In order to achieve the third object, according to the present invention, there is provided a waterproof plug molded by a rapping mold, comprising: 
     a cylindrical wall portion surrounding a through hole extending in the rapping direction, to which an electric wire is inserted; and 
     an annular convex formed on one of an inner face and an outer face of the cylindrical wall portion so as to extend in a direction perpendicular to the rapping direction, 
     wherein the other one of the inner face and the outer face of the cylindrical wall portion is made straight with regard to the rapping direction. 
     In this configuration, the mold on the part of straight face is drawn first and then the mold on the part of annular convex is drawn, so that no excessive force is applied to the waterproof plug when the mold on the part of straight face is drawn. When the mold on the part of annular convex is drawn, free deformation is permitted as the opposed side face is released, whereby no excessive force is applied to the waterproof plug at the time of rapping. In other words, no excessive force is applied to the waterproof plug in either case of drawing on the outer face or inner face of the cylindrical wall portion. Therefore, plastic deformation at the time of rapping is preventable even in a case where any material having a low elastic stress marginal value is employed. Thus, dimensional stability can be increased. 
     Preferably, the plug is provided as an individual cylindrical plug a central hole of which serves as the through hole. 
     The waterproof plug is of a so-called separate type in which it is inserted separately into the through hole between the electric wire and the housing. In a waterproof plug of this type, dimensional stability can be improved as plastic deformation is preventable at the time of rapping even in a case where the waterproof plug is molded from a material having a low elastic stress marginal value. 
     Preferably, a plurality of cylindrical portions are formed on a mat-shaped seal member. The annular convex is formed on each inner face of the cylindrical portions. 
     This waterproof plug is of a so-called mat-type in which the gap between the whole electric wire and the connector housing is sealed by fitting the waterproof plug to the rear end of the connector housing. In a waterproof plug of this type, dimensional stability can be improved as plastic deformation is preventable at the time of rapping even in a case where the waterproof plug is molded from a material having a low elastic stress marginal value. 
     Preferably, the plug is made of a thermoplastic elastomeric resin. 
     The thermoplastic elastomeric resin is a material having properties of “thermoplastic resin” simultaneously with “rubber” and by using the thermoplastic elastomeric resin to form the waterproof plug, it is possible to decrease the molding time greatly in comparison with the related rubber materials (e.g., silicone rubber and NBR). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is an exploded perspective view of a waterproof connector according to-one embodiment of the present invention; 
     FIG. 2A is a side cross-sectional view of the normal engagement of the waterproof connectors; 
     FIG. 2B is a partial cross-sectional view of the essential portion of the waterproof connector; 
     FIG. 3 is a side-cross sectional view of the state the waterproof connectors engaged at the normal engagement position are to be released by pushing an unlocking pin; 
     FIG. 4 is a side cross-sectional view of the temporary engagement of the waterproof connectors; 
     FIG. 5 is a cross-sectional side view of a temporary assembly before the terminals of the waterproof connector of the embodiment are inserted and secured; 
     FIG. 6 is a partial cross-sectional plan view of the assembly shown in FIG. 5; 
     FIG. 7 is a cross-sectional side view for explaining the assembly process for the waterproof connector, and shows the state immediately after the terminals have been inserted; 
     FIG. 8 is a cross-sectional side view of the next step following FIG. 7; 
     FIG. 9 is a cross-sectional side view of the next step following FIG. 8, and shows the waterproof connector after the assembly process has been completed; 
     FIGS. 10A and 10B are detailed diagrams showing a X portion shown, in FIG. 6, wherein FIG. 10A is a partially enlarged diagram showing the state wherein a rear holder is held temporarily, and FIG. 10B is a partially enlarged cross-sectional view of the state wherein the rear holder is held securely; 
     FIGS. 11A and 11B are diagrams showing the structure of a rubber plug used for the waterproof connector, wherein FIG. 11A is a front view and FIG. 11B is a side view; 
     FIG. 12 is a cross-sectional view taken along a line XII—XII in FIG. 11; 
     FIG. 13 is a cross-sectional view taken along a line XIII—XIII in FIG. 11; 
     FIG. 14 is a cross-sectional view taken along a line XIV—XIV in FIG. 13; 
     FIG. 15 is a sectional view showing a separate-type waterproof plug; 
     FIGS. 16A and 16B are explanatory diagrams for explaining a rapping method after the waterproof plug of FIG. 15 is molded referring to the first stage and the second stage, respectively; 
     FIG. 17 is a sectional view showing another separate-type waterproof plug; 
     FIGS. 18A and 18B are explanatory diagrams for explaining a rapping method after the waterproof plug of FIG. 17 is molded referring to the first stage and the second stage, respectively; 
     FIG. 19 is a cross-sectional view showing a related waterproof. connector; 
     FIG. 20 is a cross-sectional view showing another related waterproof connector; 
     FIG. 21 is a sectional view showing a related waterproof plug; 
     FIG. 22 is a sectional view showing a state that the related waterproof plug showing is fitted into a connector housing; 
     FIG. 23 is a cross-sectional view of a related waterproof connector; and 
     FIGS. 24A and 24B are diagrams showing the structure of a rubber plug used for the related waterproof connector, wherein FIG. 24A is a cross sectional view and FIG. 24B is a diagram as viewed from an arrow E shown in FIG.  23 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the present invention will now be described while referring to the accompanying drawings. 
     FIG. 1 is an exploded perspective view of a waterproof connector M according to one embodiment of the present invention. The waterproof connector assembly is constituted by a male connector (one connector) M and a female connector (the other connector) F. 
     The waterproof connector M comprises: a male connector housing  11 , which is made of a hard synthetic resin and which includes a plurality of terminal chambers  111 ; female terminals  20 , which are attached to the distal ends of electric wires W and which are inserted into the terminal chambers  111  of the connector housing  11 ; a spacer  13 , which is made of a hard synthetic resin and which is mounted on the lower side of the connector housing  11  to hold the female terminals  20  that are accommodated in the chambers  111 ; a front cover  12 , which is made of a hard synthetic resin and which is mounted on the lower front face of the connector housing  11  to guide male terminals  50  of a mating connector F to the female connectors  20  a mat-shaped rubber plug  14 , which includes a plurality of electric wire insertion holes  141 , corresponding to the terminal chambers  111 , and which is attached to the rear end face of the connector housing  11 ; and a rear holder  15 , which is made of a hard synthetic resin and which presses the mat-shaped rubber plug  14  against the rear face of the connector housing  11 . The waterproof connector M also includes: an unlock pin  16 , which is used to release locking when the connector M is connected to the mating connector F; and a short-circuit terminal  17 , which is used to detect faulty connections. 
     FIG. 2 is a side cross-sectional view of the state wherein the male connector M and the female connector F are engaged at the normal engagement position. FIG. 3 is a side cross-sectional view showing the state wherein the unlocking pin  16  is pushed to disengage the male connector M from the female connector F when they are engaged at the normal engagement. FIG. 4 is a side cross-sectional view of the state wherein the male connector M and the female connector F are temporarily engaged. And FIGS. 5 to  10  are diagrams showing the structure of the male connector M and the assembly procedures, while FIGS. 11 to  14  are diagrams showing the structure of the rubber cap  14  which is a waterproof seal. 
     First, the male connector M will be described while referring to FIGS. 5 to  14 . 
     As is shown in FIG. 5, multiple terminal chambers  111  are formed in the connector housing  11  while extending in the front-rear direction thereof, and lances  112 , formed on the lower faces of the individual terminal chambers  111 , serve as flexible terminal lock arms that prevent the female terminals  20  that are inserted from slipping. Furthermore, as is shown in FIGS. 2 and 3, in order to insert holding arms  154  and  155 , which are attached to the rear holder  15  for which a description will be given later, insertion holes  114  and  118  for receiving the holding arms are formed at locations that avoid the terminal chambers  111  in the connector housing  11 . A lock arm  115 , formed on the upper face of the connector housing  11 , locks a connector housing  4  of the mating connector F (see FIG. 1) when the waterproof connector M is connected to the mating connector F. A recessed portion  113  for receiving the spacer  13  is formed in the lower face of the connector housing  11 . 
     A free end  115   c  of the lock arm  115  is extended toward the rear, while a distal fulcrum  115   a  is cantilevered, so that the free end  115   c  is flexibly bent downward, from its constant position, at the distal fulcrum  115   a . A protrusion  115   b  is formed on the upper face of the lock arm  115  between the distal fulcrum  115   a  and the free end  115   c . When the connectors M and F engage each other at their normal position, the protrusion  115   b  engages a protrusion (not shown) formed on the connector housing  401  of the mating connector F. An inclined, unlock operating portion  115   d , having a U-shape in cross section, slopes downward from the free end  115   c  of the lock arm  115 . And when the inclined wall of the unlock operating portion  115   d  is contacted from the rear by the distal end of the unlock pin  16 , it responds by moving downward, and this movement causes the lock arm  115  bend down in the unlocking direction. As is shown in FIG. 2, when the connectors M and F engage each other at their normal position, the protrusion  115   b  engages a protrusion  403  formed on the hood  402  of the female connector housing  401 . 
     An inclined, unlocking portion  115   d  (an inclined portion), having a U-shape in cross section, slopes downward from the free end  115   c  of the lock arm  115 . And when the inclined wall of the unlocking portion  115   d  is contacted from the rear by the distal end of the unlocking pin  16 , it responds by moving downward, which causes the lock arm  115  to bend down in the unlocking direction. Further, when the bent lock arm  115  is to be returned to its original position, the unlocking pin  16  can be pushed backward by the action of the inclined wall face. 
     An unlock pin through hole  116  is formed in the rear wall of the connector housing  11  and extends forward toward the unlock operating portion  115   d  of the lock arm  115 . The distal end of a shaft  161  of the unlock pin  16  is inserted into the unlock pin through hole  116 . At the distal end of the shaft of the unlock pin  16  is formed a semi-spherical portion  162 , which can be brought into contact with the inclined unlock operating portion  115   d  of the lock arm  115 . 
     The unlocking pin  16  is formed with its axial direction extending to the front and to the rear, and can freely slide forward and backward, perpendicular to the vertical direction in which the free end  115   c  of the lock arm  115  is bent. 
     The short-circuit terminal  17  is stored in the space below the lock arm  115 . Provided for the short-circuit terminal  17  is a spring  171 , so that the short-circuit terminal  17  can interact with the bending of the lock arm  115 , and projecting from the upper face of the spring  171  is a contact point  172 . The short-circuit terminal  17  is one component of a mechanism that electrically detects the engagement of the waterproof connector M and the mating connector F. 
     That is, as is shown in FIG. 2, when the male waterproof connector M and the female connector F are engaged at the normal engagement-position, the two engagement detection terminals  450  of the female connector F contact the contact point  172 , and the engagement detection terminals  450  are short-circuited. Further, as is shown in FIG. 4, when the male connector M and the female connector F are not fully engaged, due to the interference of the protrusions  403  and  115 , the spring  171  is pushed downward by the lock arm  115 , which is bent downward. As a result, the contact point  172  does not contact the engagement detection terminals  450 , and the engagement detection terminals  450  are not short-circuited. Therefore, an external examination can be conducted to determine whether the engagement detection terminals  450  have been short-circuited and whether the connectors M and F are fully or only partially engaged. The short-circuit terminal  17  is thus a required component of the pertinent mechanism. 
     The front cover  12  is mounted on the lower front face of the connector housing  11 . Guide holes  121  formed in the front cover  12  guide the male terminals  50  (see FIG. 1) that are inserted. The spacer  13  is inserted into the recessed portion  113  that is provided in the lower face of the connector housing  1 . 
     The spacer  13  is used together with the lances  112  to double-lock the terminals  20  that are inserted and accommodated in the terminal chambers  111 . When the spacer  13  is located at the temporary holding position in FIG. 2, the insertion of the terminals  20  is permitted. But when the spacer  13  is pushed in until it occupies the secure holding position in FIG. 9, the spacer  13  and the lances  112  together double-lock the terminals  20 . 
     Through holes  131  for receiving the terminals  20  are formed in the spacer  13  correspond to the terminal chambers  111  of the connector housing  11 . There is also formed holes  132  for receiving the lower holding arms (which will be described later) of the rear holder  15  in the spacer  13 . Protrusions  133  are formed on the inner bottom faces of the lower holding arm insertion holes  132 , and when the spacer is pushed up into the security holding position, the protrusions  133  engage holes  154   a  in the holding arms  154  so as to securely lock the rear holder  15  in the constant position. The engagement holes  154   a  and the protrusions  133  constitute one member for securely locking the rear holder  15 . 
     The mat-shaped rubber plug  14  is mounted on the rear wall of the connector housing  11  as the waterproof seal, and is sandwiched between the connector housing  11  and the rear holder  15  that is provided at the rear. The material that can be used for the rubber plug  14  is not limited to rubber, and another flexible material can be employed for the cap  14 . For example, the cap  14  also may be formed of a soft resin. 
     As is shown in FIGS. 11 to  14 , multiple insertion holes  141  are formed in the mat-shaped rubber plug  14  so as to correspond to the terminal chambers  111 . Also formed therein are a through hole  145 , into which the unlock pin  16  is inserted while forming a waterproof seal, and through holes  144  and, 148 , into which the holding arms  154  and  155  of the rear holder  15  are inserted while forming a waterproof seal. 
     A recessed portion  143  is formed in the rear face of the rubber plug  14 , while cylindrical walls  142  are left around the individual electric wire insertion holes  141 . The outer circumference of the recessed portion  143  is defined by an outer peripheral wall  147 , which is as tall as the cylindrical walls  142 . As is shown in FIG. 2, when the male connector M is fitted into the. female connector F, the outer peripheral wall  147  is closely sealed with the inner face of the hood  402  of the female connector housing F. When the adjacent cylindrical walls  12  are connected together to form blocks, as is shown in FIG. 14, four blocks B 1  to B 4  are formed. First, the cylindrical walls  142  around the four insertion holes  141  that are located at the vertexes of a square are connected together to form the first block B 1  and the second block B 2 . Similarly, the cylindrical walls  142 , around the insertion holes  141  that are arranged in a single row, are connected together to form the third block B 3  and the fourth block B 4 . 
     The through hole  145 , into which the unlock pin  16  is inserted, and through holes  144  and  148 , into which the holding arms  154  and  155  of the rear holder  15  are inserted, are located at positions that avoid the blocks B 1  to B 4 . 
     As is shown in FIGS. 12 and 13, on each of the inner faces of the insertion holes  141 , which are enclosed by the cylindrical walls  142 , annular convex portions  141   a  having a waveform shape in cross section are arranged at two stages in the direction in which the insertion holes  141  extend, so that the contact force relative to the electric wires W is increased. Similarly, on the outer face of the outer peripheral wall  147 , which defines the recessed portion  143 , ring-shaped recessed portions  147   a  having a waveform shape in cross section are arranged at two stages in order to increase the contact force relative to the connector housing  401  when the connectors M and F are engaged. In addition, a squeeze  142   a  and a squeeze  147   b  (portions expanded slightly outward) are formed at the base side of the outer face of each cylindrical wall  142  and the inner face of the outer peripheral wall  147 , respectively. They are squeezed when a raised portion  152  (which will be described later) on the rear holder  15  is pressed into the recessed portion  143 . 
     A cylindrical wall  146  for the unlock pin  16  is formed around the through through hole  145  that is formed in the rubber plug  14 . The cylindrical wall  146  projects outward through the front face of the rubber plug  14 , so that it can be fitted into the through hole  116  in the connector housing  11 . On the inner face of the cylindrical wall  146 , annular convex portions  145   a  are formed at two stages in order to increase the force with which the outer face of the shaft  161  of the unlock pin  16  is contacted. 
     The waterproof plug  14  is formed by rapping molds with the direction of passing the insertion holes  141  and  145  therethrough as a rapping direction. 
     The above-described annular convex portions  141   a ,  145   a  and  147   a  formed on the inner peripheral faces of the cylindrical walls  142  and  146  or the outer peripheral face of the outer peripheral wall  147  are formed in a direction crossing the rapping direction. Therefore, the formation of annular convex portions on the face opposite to where the annular convex portions  141   a ,  145   a  and  147   a  may result in developing the same problem as before at the time of drawing. 
     The straight face is formed as a face opposite to the face on which the annular convex portions  141   a ,  145   a  and  147   a  are formed and instead squeezes  142   a ,  146   a  and  147   b  to press are secured by slightly increasing the wall thickness of the face. 
     More specifically, on the base side of the outer peripheral face of the cylindrical wall  142  around the insertion hole  141  for the electric wire W, there is provided the squeeze  142   a  that is pressed when the raised portion  152  of the rear holder  15  is press-fitted into the recess  143 . On the base side of the outer peripheral face of the cylindrical wall  146  around the through hole  145  for the unlock pin  16 , there is also provided the squeeze  146   a  that is pressed when the unlock pin  16  is inserted into the cylindrical-wall  146  while the cylindrical wall  146  is fifted into the through hole  116  of the connector housing  11 . On the base side of the inner peripheral face of the outer peripheral wall  147 , further, there is provided the squeeze  147   b  that is pressed when the raised portion  152  of the rear holder  15  is press-fitted into the recess  143 . 
     Although the portions where the squeezes  142   a ,  146   a  and  147   b  are provided respectively have the annular convex portions  141   a ,  145   a  and  147   a  on their opposite sides, these portions are formed with the straight faces and consequently hardly subjected to plastic deformation at the time of rapping as in the previous embodiments of the invention, so that dimensional stability is readily maintained. 
     In the rear holder  15  that presses the rubber plug  14  against the connector housing  11 , insertion holes  151  are formed so that they to correspond to the insertion holes  141  in the rubber plug  14 . On the front face of the rear holder  15 , the raised portion  152  is formed that is fitted into the recessed portion  143  of the rubber plug  14 . The walls of the raised portion  152  that interferes with the cylindrical walls  142  and the outer peripheral wall  147  serve as pressing walls (assist walls)  152   a  that press the. squeezes  142   a  and  147   b  on the rubber plug  14 . While the squeezes  142   a  and on the cylindrical walls  142  and the squeeze  147   b  are pressed by the assist walls  152   a , the raised portion  152  is pressed into the recessed portion  143 . As a result, the compressive force produced by the electric wire insertion-holes  141  and exerted in the direction of the diameter can act on the cylindrical walls  142 , and the backup force acting from the inner side to the outer side can be provided for the outer peripheral wall  147 . 
     Furthermore, a through hole  153 , through which the unlock pin  16  is inserted, is formed in the rear holder  15 , so that when the shaft  161  of the unlock pin  16  is inserted via the through hole  153 , it slides freely in the insertion direction. And at the head of the unlock pin  16 , a disk-shaped operating portion  163  is formed for applying finger pressure. 
     The lower holding arms  154  shown in FIG.  5  and the upper holding arms  155  shown in FIGS. 3 and 7 projected outward from the front face of the rear holder  15 . The lower holding arms  154  include the engagement holes  154   a  into which the protrusions  133  of the spacer  13  are fitted, while the upper holding arms  155  each include a first protrusion  155   a  and a second protrusion  155   b  that selectively engage a protrusion  117  on the connector housing  11 . 
     Further, as is shown in FIG. 10A, when the first protrusion  155   a  is located in front of the protrusion  117  and the second protrusion  155   b  is located at the rear of the protrusion  117 , the rear holder  15  is temporarily halted, and as is shown in FIG. 2, the raised portion  152  has not yet been fitted into the recessed portion  143  of the rubber plug  14 . 
     As is shown in FIG. 10B, when the second protrusion  155   a  is located in front of the protrusion  117 , the rear holder  15  is securely held, and as is shown in FIGS. 8 and 9, the raised portion  152  has been fitted into the recessed portion  143  of the rubber plug  14 . 
     The first protrusion  155   a , the second protrusion  155   b  and the protrusion  117   c  constitute the means for temporarily holding the rear holder  15  on the connector housing  11 . The second protrusion  155   b  and the protrusion  117  constitute one of the member for securely holding the rear holder  15  on the connector housing  11 . 
     The assembly process for the waterproof connector M will now be explained. 
     As is shown in FIG. 2, first, the front cover  12  is mounted on the lower front face of the connector housing  11 , and the spacer  13  is inserted from below into the spacer insertion recessed portion  113  that is formed in the lower face of the connector housing  11 . At this time, the spacer  13  is held temporarily in the connector housing  11 . 
     The rubber plug  14  is placed against the rear wall of the connector housing  11 , and the cylindrical wall  146 , which is projects outward around the unlock pin through hole  145  on the front face of the rubber plug  14 , is fitted into the unlock pin through hole  116  that is formed in the connector housing  11 . 
     Then, the rear holder  15  is positioned on the rear face of the rubber plug  14 , and the lower and upper holding arms  154  and  155  of the rear holder  15  are respectively inserted via the through holes  144  and  148  in the rubber plug  14  into the insertion holes  114  and  118  in the connector housing  11 . 
     As is shown in FIG. 10A, the upper holding arms  155  are inserted until they reach a position whereat the first protrusions  155   a  have passed the protrusion  117  on the connector housing  11  and the second protrusion  155   b  is held behind the protrusion  117 . In this state, the rear holder  15  is temporarily held on the connector housing  1 . 
     The unlock pin  16  is inserted via the through hole  153  in the rear holder  15 , and into the through hole  145  in the cylindrical wall  146 , which is fitted into the through hole  116  in the connector housing  11 . This is the temporary assembled state shown in FIGS. 5 and 6. 
     Next, in the state wherein the rear holder  15  is held temporarily, as is shown in FIG. 7, the terminals  20  attached to the distal ends of the electric wires W are inserted via the insertion holes  151  in the rear holder  15  and the insertion holes  141  in the rubber plug  14  and are accommodated in the terminal chambers  111  in the connector  11 . In the state where the rear holder  15  is held temporarily, the raised portion  152  of the rear holder  15  does not interfere with the cylindrical walls  142  of the insertion holes  141  in the rubber plug  14 , i.e., the raised portion  152  is not fitted into the recessed portion  143  of the rubber plug  14  and pressure is not applied to the cylindrical walls  142 . Thus, free expansion of the cylindrical walls  142  is permitted, so that the terminals  20  can be easily inserted. 
     When the terminals  20  are inserted into and retained by the terminal chambers  111  of the connector housing  11 , the lances  112  are flexibly bent and recovered as the terminals  20  are passed. 
     As is shown in FIG. 8, the rear holder  15  is pushed and moved from the temporary holding position to the securely held position. Then, the raised portion  152  of the rear holder  15  is pushed in the recessed portion  143  of the rubber plug  14 , and the squeezes  142   a  on the outer faces of the cylindrical walls  142  and the squeeze  147   b  on the inner face of the outer peripheral wall  147  are pressed by the wall  152   a  of the raised portion  152 . Thus, since the compression force toward the diameter of the electric wire insertion holes  141  acts on the cylindrical walls  142 , the cylindrical walls  142  closely contact the wires W, so that the portions that the electric wires W have penetrated are sealed. Further, the outer peripheral wall  147  can be backed up from the inner side. At the same time, as is shown in FIG. 10B, since the upper holding arms  155  of the rear holder  15  are moved forward, the second protrusion  155   b  is passed over the, protrusion  117  of the connector housing  11 , and the rear holder  15  is securely held on the connector housing  11 . 
     Further, since the unlock pin  16  is also inserted in the through hole  145  of the rubber plug  14 , the other portions are securely sealed. In this case, the shaft  161  of the unlocking pin  16  is inserted into the through hole  145  of the rubber cap  14  that is fitted in the unlocking pin through hole  116  of the connector housing  11 . Thus, the cylindrical wall  146  of the rubber cap  14  is compressed, and utilizing the generated reactive force, the cylindrical wall  146  brought more closely into contact with the connector housing  11  and the unlocking pin  16 , thus ensuring that a strong seal is provided at this portion. 
     Finally, as is shown in FIG. 9, the spacer  13  is pushed up to securely lock the assembly. At this time, the protrusions  133  in the insertion holes  132  of the spacer  13  are inserted in the engagement holes  154   a  of the rear holder  15 , so that the holding arms  154  are locked. Thus, the rear holder  15  is securely held by the lower and upper holding arms  154  and  155 , and the assembly of the waterproof connector M is therefore complete. 
     For the thus arranged waterproof connector M, since the cylindrical walls  142  around the insertion holes  141  of the rubber plug can be freely expanded when the terminals  20  are to be inserted into the terminal chambers  111  of the connector housing  11 , the insertion of the terminals  20  can be performed easily. Further, after the terminals have been inserted, the raised portion  152  of the rear holder is pressed into the recessed portion  143  of the rubber plug  14 , and the cylindrical walls  142  are compressed and closely contact the outer faces of the electric wires W. In this manner, the highly sealed condition can be maintained. 
     Furthermore since the cylindrical walls  142  of the rubber plug  14  are not independently formed, but are united with several other walls to form blocks, unlike the related art, wherein a gap is ensured around the cylindrical walls  142  that permits them to be expanded, the pitch between the electric wire insertion holes  141  can be reduced. 
     With the waterproof plug  14  of this waterproof connector M, it is possible to increase the dimensional stability of the cylindrical wall  142  around the electric-wire insertion hole  141 , the cylindrical wall  146  around the through hole  145  and the outer peripheral wall  147  that serves for sealing the waterproof connector by forming the annular convex portions  141   a ,  145   a  and  147   a  on only one face and the straight face on the other. Thus, high sealing performance can be demonstrated for certain. 
     A brief explanation will now be given, while referring to FIGS. 2 to  4 , for the female connector F that engages the male connector M. 
     The connector housing  401  of the female connector F includes the hood  402  into which the male connector M is fitted. A protrusion  403  formed on the upper wall of the hood  402  engages the protrusion  115   b  of the lock arm  115  of the male connector M. 
     A rear wall  405  that the distal end of the male connector M contacts is formed in the connector housing  401 . A normal male terminal  50  that is connected to the male terminal  20  projects linearly forward from the rear wall  405 . From the top of the rear wall  405 , the engagement detection terminal  450  projects linearly forward, as does the normal male terminal  50 . 
     Since the force in the bending direction is exerted against the engagement detection terminal  450  when it contacts the short-circuit terminal  17  of the male connector M, the engagement detection terminal  450  is supported by a support wall  406 , which projects forward above the terminal  450 , that prevents the terminal  450  from being bent. 
     When the female connector F engages the male connector M, the inner face at the distal end of the hood  402  of the female connector housing  401  closely contacts the outer peripheral wall  147  of the rubber cap  14  that is located at the rear of the male connector. As a result, the waterproof space S is defined between the connectors M and F by the rubber cap  14 . Since the junctures of the female terminal  20  and the male terminal  50 , the lock arm  115 , the engagement detection terminals  40  and  50  and the short-circuit terminal  17  are accommodated in the waterproof space S, water, mud and dust are prevented from entering these components from the outside. 
     As is shown in FIG. 2, when the male connector M normally engages the female connector F, the protrusion  115   b  on the lock arm  115  fully engages the protrusion  403  in the female connector housing  401 , and the lock arm  115  is returned to its original position (it is not bent). Thus, the short-circuit terminal  17  contacts the engagement detection terminals  450 , and a short circuit between the engagement terminals  450  is detected by an external circuit, thereby confirming the normal engagement of the connectors M and F. 
     Furthermore, as is shown in FIG. 4, when the male connector M temporarily engages the female connector F, the protrusion  115   b  on the lock arm impinges on the protrusion  403  on the female connector housing  401 , and the lock arm  115  is bent downward from its original position. As a result, the spring piece  171  of the short-circuit terminal  17  is pushed and bent downward by the lock arm  115 . Therefore, the contact point  172  and the engagement detection terminals  450  do not contact each other, and a short-circuit state between the engagement detection terminals  450  does not occur. Thus, the non-short-circuit state between the engagement detection terminals  450  can be detected by the external circuit, thereby confirming the half engagement state of the connectors M and F. 
     As is shown FIG. 3, in order to disengage the connectors M and F in the normal engagement state shown in FIG. 2, the operating portion  163  of the unlocking pin  16  that is projected to the rear end of the male connector M is pushed in the sliding direction. Then, the semi-spherical distal end  162  of the unlocking pin  16 , which penetrates the rubber cap  14  and extends into the waterproof space S, contacts the inclined wall face of the unlocking portion  115   d  of the lock arm  115 . When the unlocking pin  16  is pushed farther in, due to the action of the inclined face of the unlocking portion  115   d , the lock arm  115  is bent downward, perpendicular to the direction in which the unlocking pin  16  slides. Therefore, when the connectors M and F are to be separated, since in this state the protrusion  115   b  is disengaged from the protrusion  403 , accordingly, the connectors M and F are released. In this case, since the unlocking portion  115   d  is U-shaped in cross section, the distal end of the unlocking pin  16  always appropriately abuts upon the inclined rear wall of the unlocking portion  115   d , and does not slide off the unlocking portion  115   d.    
     Since the semi-spherical portion  162  is formed at the distal end of the shaft  161  of the unlocking pin  16 , there is minimal contact between the distal end of the unlocking pin  16  and the unlocking portion  115   d , and the sliding movement of the unlocking pin  16  can be precisely converted into the bending of the lock arm  115 . 
     During the unlocking process, in response to the return of the lock arm  115  to its original position, the unlocking pin  16  is slid backward by the inclined unlocking portion  115   d . Thus, a spring for returning the unlocking pin  16  to the original position is not required. 
     As is described above, the unlocking pin  16  need only slide in the direction in which it penetrates the rubber cap  14 , so that the lock arm  115  can be released. Thus, a precise operation can be easily performed, and the entry of water via the portion whereat the unlocking pin  16  is inserted can be prevented. In addition, since the unlocking pin  16  must only be slid forward and backward, at the portion whereat the unlocking pin  16  is inserted, an excellent seal can be maintained. Especially since the cylindrical wall  146 , which when compressed exerts increased contact force, is formed at the portion through which the unlocking pin  16  is inserted, a strong seal can be maintained. 
     The separate-type waterproof plug can be used for the above waterproof connector instead of the mat-type waterproof plug. 
     FIG. 15 is a sectional view of one example of a separate-type waterproof plug  210  according to the invention. The waterproof plug  210  has an insertion hole  212  for receiving an electric wire, and a cylindrical wall  213  surrounding the insertion hole  212 . More specifically, the central hole is used as the electric-wire insertion hole  212 , and the peripheral wall is used as the cylindrical wall  213  in order to form an independent substantially tubular body. 
     The waterproof plug  210  made of thermoplastic elastomeric resin is formed, by rapping molds with the direction of passing the: insertion hole  212  therethrough as a rapping direction. A plurality stages of annular convex portions  215  are also formed on only the inner peripheral face of the cylindrical wall  213  along a peripheral direction crossing the rapping direction, and the outer peripheral face thereof is formed as a straight face  214 . 
     When the waterproof plug  210  is press-fitted in between the outer periphery of an electric wire and the inner periphery of the insertion hole of a connector housing, the annular convex portions  215  on the inner peripheral face are used to make the straight face  214  of the outer periphery stick fast to the inner peripheral wall of the insertion hole of the connector housing as the curved portions are compressed in order to increase the adhesion to the electric wire as well in the related art. 
     When the waterproof plug  210  is formed by molding, there are used a stationary mold  221  for mainly molding the outer peripheral face and a moving mold  222  for mainly molding the inner peripheral face as shown in FIG.  16 . The stationary mold  221  is provided with a recessed molding face  21   a  for forming the outer peripheral shape of the waterproof plug  210 . The moving mold  222  is provided with a projected molding rod  223  for forming the inner peripheral shape of the waterproof plug  210 . The molding face  223   a  has a corrugated configuration for forming the inner peripheral shape of the annular convex portions  215 . 
     The moving mold  222  is provided with a first moving mold  222   a  on the back side and a second moving mold  222   b  on the front side the second moving mold  222   b  being longitudinally movable relative to the first moving mold  222   a . The molding rod  223  is projected from the first moving mold  222   a  on the back side and its front end portion is projected forward from the opening  222   c  of the second moving mold  222   b . The second moving mold  222   b  is provided with an extrusion rod  225  for forcing the second moving mold  222   b  forward from the first, moving mold  222   a.    
     The stationary mold  221  and the moving mold  222  are clamped together and thermoplastic elastomeric resin is injected to mold the waterproof plug  210 . Then the moving mold  222  is opened in the direction of an arrow A as shown in FIG.  16 A. 
     At this time, the outer peripheral face of the cylindrical wall  213  of the waterproof plug  210  is the straight face  214 , whereas the inner peripheral face thereof is formed with the annular convex portions  215  forming an uneven face, whereby the waterproof plug  210  is drawn out of the stationary mold  221  without any excessive force applied thereto before being left on the side of the moving mold  222 . 
     As shown in FIG. 16B, the waterproof plug  210  held on the outer periphery of the front end portion of the molding rod  223  is pulled down from the molding rod  223  by using the extrusion rod  225  to force the second moving mold  222   b  forward in the direction of an arrow B. The waterproof plug  210  thus produced is obtainable. 
     In the above process of production, since the waterproof plug  210  is drawn along the straight face  214  when the waterproof plug  210  is drawn from the stationary mold  221  at the first stage, no excessive force becomes applied to the waterproof plug  210 . When the waterproof plug  210  is drawn from the moving mold  222  equipped with the molding rod  223  at the second stage, moreover, its opposed outer peripheral face has already been released with the effect of allowing free deformation, whereby no excessive force also becomes applied to the waterproof plug  210  because of drawing. 
     In other words, no excessive force becomes applied to the waterproof plug  210  even when not only the outer peripheral face but also the inner peripheral face is drawn and because plastic deformation is preventable even in a case where thermoplastic elastomeric resin having a lower elastic stress marginal value is employed, dimensional stability can be increased. 
     Another example of the separate-type waterproof plug according to the invention will be described. 
     FIG. 17 is a sectional view of a separate-type waterproof plug  230  according to the second embodiment of the invention. The waterproof plug  230  has an insertion hole  232  for receiving an electric wire, and a cylindrical wall  233  surrounding the insertion hole  232 . More specifically, the central hole is used as the insertion hole  232 , and the peripheral wall is used as the cylindrical wall  233  in order to form an independent substantially tubular body. 
     The waterproof plug  230  made of thermoplastic elastomeric resin is formed by rapping molds with the direction of passing the electric-wire insertion hole  232  therethrough as a rapping direction. A plurality of stages of annular convex portions  234  are also formed on only the outer peripheral face of the cylindrical wall  233  along a peripheral direction crossing the rapping direction, and the inner peripheral face thereof is formed as a straight face  235 . 
     When the waterproof plug  230  is press fitted in between the outer periphery of the electric wire and the inner periphery of the insertion hole of the connector housing, the annular convex portions  234  on the outer peripheral face are used to make the straight face  235  of the inner periphery stick fast to the outer periphery of the electric wire as the curved portions are compressed in order to increase the adhesion to the electric wire as before. 
     When the waterproof plug  230  is formed by molds, there are used a stationary mold  241  for mainly molding the inner peripheral face and a moving mold  242  for mainly molding the outer peripheral face as shown in FIG.  18 . The stationary mold  241  is provided with a projected molding rod  243  for forming the inner peripheral shape of the waterproof plug  230 . The moving mold  242  is provided with a recessed molding face  242   a  for forming the outer peripheral shape of the waterproof plug  230 . The molding face  242   a  has a corrugated configuration for forming the outer peripheral shape of the annular convex portions  234 . Further, the moving mold  242  is provided with an extrusion rod  244  so that the waterproof plug  230  left in the moving mold  242  may be forced out. 
     The stationary mold  241  and the moving mold  242  are clamped together and thermoplastic elastomeric resin is injected to mold the waterproof plug  230 . Then the moving mold  242  is opened in the direction of an arrow C as shown in FIG.  18 A. 
     At this time, the inner peripheral face of the cylindrical wall  233  of the waterproof plug  230  is the straight face  235 , whereas the outer peripheral face thereof is formed with the annular convex portions  234  forming an uneven face, whereby the waterproof plug  230  is drawn out of the stationary mold  241  without any excessive force applied thereto before being left on the side of the moving 
     As shown in FIG. 18B, the waterproof plug  230  is pulled down by forcing out the waterproof plug  230  left in the moving mold  242  forward in the direction of an arrow D by the extrusion rod  244 . The waterproof plug  230  thus produced is obtainable. 
     In the above process of production, since the waterproof plug  230  is drawn along the straight face  235  when the waterproof plug  230  is drawn from the stationary mold  241  at the first stage, no excessive force becomes applied to the waterproof plug  230 . When the waterproof plug  230  is drawn from the moving mold  242  at the second stage, moreover, its opposed inner peripheral face has already been released with the effect of allowing free deformation, whereby no excessive force also becomes applied to the waterproof plug  230  because of drawing. 
     In other words, no excessive force becomes applied to the waterproof plug  230  even when not only the inner peripheral face but also the outer peripheral face is drawn and because plastic deformation is preventable even in a case where thermoplastic elastomeric resin having a lower elastic stress marginal value is employed, dimensional stability can be increased. 
     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.