Abstract:
An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The disclosure of Japanese Patent Application No. 2012-262918 filed on Nov. 30, 2012 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to an insert molded article in which a plurality of types of parts are used for specific insert parts, an insert molding method for manufacturing this insert molded article, and an insert molding apparatus used in this insert molding method. 
         [0004]    2. Description of Related Art 
         [0005]    Insert molding is known as a method for integrating a part with resin. In insert molding, a part is integrated with set resin by injecting molten resin around the part while the part is arranged inside of a forming die. For example, Japanese Patent Application Publication No. 2005-297387 (JP 2005-297387 A) describes a case for an electronic control unit as an insert molded article. 
         [0006]    Also, Japanese Patent Application Publication No. 2012-28029 (JP 2012-28029 A) describes technology for preventing wrong assembly in a lever-type connector. With the lever-type connector described in JP 2012-28029 A, a wrong-assembly preventing protrusion that prevents wrong assembly of a wire cover is provided on the wire cover. The wrong-assembly preventing protrusion abuts against an arm of a lever when the wire cover is assembled in the opposite direction from the assembly direction of the lever. Wrong assembly of the wire cover is able to be detected by the wrong-assembly preventing protrusion abutting against the arm of the lever. 
         [0007]    There are cases in which a plurality of types of parts are used for specific insert parts in an insert molded article. In such cases, when the specific insert parts are assembled in a forming die, it is possible that, of the specific insert parts, one type of insert part may be wrongly assembled in a location where a different type of insert part is supposed to be assembled. However, with conventional insert molding technology, no thought has been given to how to detect wrong assembly when the type of insert part is wrong. Therefore, it is difficult to determine whether a wrong part has been assembled or a correct part has been assembled, when there is only a small difference in appearance between different types of insert parts, for example. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention thus provides an insert molded article, an insert molding method, and an insert molding apparatus, in which wrong assembly of an insert part is able to be easily detected. 
         [0009]    A first aspect of the invention relates to an insert molded article that includes a first part; and a resin case having a protruding portion that is formed exposing a portion of the first part, and is adjacent to a portion where the first part is exposed, and protrudes from a surface of the resin case. 
         [0010]    A second aspect of the invention relates to a method for forming an insert molded article that includes a first part, and a resin case having a protruding portion that is formed exposing a portion of the first part, and is adjacent to a portion where the first part is exposed, and protrudes from a surface of the resin case. This method includes arranging the first part in a forming die; arranging a mounting part that has a passage that passes through a cross-section thereof, so as to cover a portion where the first part is exposed from the resin case and such that the passage is blocked off by the first part; and forming the resin case by pouring molten resin into the forming die. 
         [0011]    A third aspect of the invention relates to an insert molding apparatus that includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged. 
         [0012]    According to these aspects it is possible to easily determine whether a wrong insert part has been assembled or a correct insert part has been assembled. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
           [0014]      FIG. 1  is a perspective view of an insert molded article according to one example embodiment of the invention; 
           [0015]      FIG. 2  is a side view and a sectional view of insert nuts; 
           [0016]      FIG. 3  is a block diagram schematically showing an insert molding apparatus; 
           [0017]      FIG. 4  is a perspective view of a first mounting member; 
           [0018]      FIG. 5  is a side view of a state in which the first mounting member is attached to a second type of nut arranged on a first placement portion in the insert molding apparatus; 
           [0019]      FIG. 6  is a perspective view of a corner portion of an insert molded article when an insert nut is not wrongly assembled; and 
           [0020]      FIG. 7  is a perspective view of a corner portion of the insert molded article when the insert nut is wrongly assembled. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0021]    Hereinafter, example embodiments of the invention will be described in detail with reference to  FIGS. 1 to 7 . 
       Insert Molded Article   
       [0022]      FIG. 1  is a perspective view of an insert molded article  10  according to one example embodiment of the invention. The insert molded article  10  in this example embodiment is a case for an electronic control unit (ECU). The insert molded article  10  is a case that is generally rectangular-shaped when viewed from above and is open on top, as shown in  FIG. 1 . Insert nuts  11  and  12  are embedded, as specific insert parts (specific parts) for which a plurality of types of parts are used, in the insert molded article  10 . The insert nuts  11  and  12  are embedded in each of four corners of the insert molded article  10 . The electronic control unit is such that a lid member, not shown, that covers the opening of the insert molded article  10  is fixed by bolts that fasten to the insert nuts  11  and  12 . Transparent insert parts in the area inside the broken line in  FIG. 1  are indicated by broken lines. Insert parts other than the insert nuts  11  and  12  and a bus bar  15  that will be described later are omitted in  FIG. 1 . 
         [0023]      FIG. 2  is a side view and a sectional view of the insert nuts  11  and  12 . A first type of nut  11  and a second type of nut  12  are used for the four insert nuts  11  and  12  of the insert molded article  10 . In  FIG. 2 , the insert nuts  11  and  12  are shown in a side view on the left side of the dashed line and in a sectional view on the right side of the dashed line. As shown in  FIG. 1 , in the insert molded article  10 , there are three of the first type of nut  11 , and one of the second type of nut  12 . The first type of nut  11  and the second type of nut  12  are both formed in a generally cylindrical shape. The shape and dimensions of an end portion of the first type of nut  11  are different from the shape and dimensions of an end portion of the second type of nut  12 . 
         [0024]    Each of the first type of nuts  11  is embedded in the insert molded article  10  such that a portion of the first type of nut  11  is exposed. With the insert molded article  10 , a recessed portion  130  and a protruding portion  131  that will be described later are formed around each of the first type of nut  11  (see  FIG. 6 ). An upper end surface of the second type of nut  12  is overlapped by a metal bus bar  15 , so the second type of nut  12  differs from the first type of nut  11  in that the upper end surface is not exposed. One end of the bus bar  15  has a through-hole through which a bolt can be inserted. The other end of the bus bar  15  is connected to a heat sink, not shown, provided on the insert molded article  10 . 
         [0025]    A portion of the first type of nut  11  except for a first end portion  11   b  and a second end portion  11   c  is a knurled portion  11   a  that has been knurled. An outer diameter of the knurled portion  11   a  is uniform in an axial direction. Also, with the first type of nut  11 , the first end portion  11   b  and the second end portion  11   c  are the same shape and size. Each end portion  11   b  and  11   c  has a smooth cylindrical surface as a result of being cut (i.e., machined). An outer diameter of each end portion  11   b  and  11   c  is uniform in the axial direction, and is just slightly smaller than the outer diameter of the knurled portion  11   a.    
         [0026]    A portion of the second type of nut  12  except for a first end portion  12   b  is a knurled portion  12   a  that has been knurled. A second end portion  12   c  is part of the knurled portion  12   a . An outer diameter of the knurled portion  12   a  is uniform in the axial direction. Also, the first end portion  12   b  has a smooth cylindrical surface as a result of being cut (i.e., machined). An outer diameter of the first end portion  12   b  is uniform in the axial direction, and is just slightly smaller than the outer diameter of the knurled portion  12   a.    
         [0027]    Continuing on, the first type of nut  11  and the second type of nut  12  will be compared. A height of the first type of nut  11  is higher than a height of the second type of nut  12  by an amount corresponding to the thickness of the bus bar  15 . Also, the outer diameter of the knurled portion  11   a  of the first type of nut  11  is the same as the outer diameter of the knurled portion  12   a  of the second type of nut  12 . The outer diameter of the knurled portions  11  a and  12   a  is 9 mm, for example. Also, the outer diameter of the end portions  11   b  and  11   c  of the first type of nut  11  is the same as the outer diameter of the first end portion  12   b  (i.e., the cut end portion) of the second type of nut  12 . The outer diameter of these cut end portions  11   b ,  11   c , and  12   b  is 8.5 mm, for example. The outer diameter of the second end portion  12   c  of the second type of nut  12  is just slightly larger than the outer diameter of the cut end portions  11   b ,  11   c , and  12   b.    
       Insert Molding Apparatus  
       [0028]    Continuing on, an insert molding apparatus  100  used to manufacture the insert molded article  10  will now be described. 
         [0029]      FIG. 3  is a block diagram schematically showing the insert molding apparatus  100 . The insert molding apparatus  100  includes a forming die  101  that has an upper die  102  and a lower die  103 , an opening/closing mechanism, not shown, for opening and closing the forming die  101 , a resin injecting device  104  for injecting molten resin inside the forming die  101 , and a plurality of mounting members  111  and  112  (a so-called piece for insert molding), as shown in  FIG. 3 . A fill port  110  into which a nozzle of the resin injecting device  104  is inserted is formed in the forming die  101 . 
         [0030]    A first placement portion  121  for arranging the first type of nut  11  and a second placement portion  122  for arranging the second type of nut  12  are formed on a bottom surface of the lower die  103 . The first placement portion  121  is provided in three locations, of the corner portions in four locations on the bottom surface of the lower die  103 . The second placement portion  122  is provided in the remaining one location. The first placement portion  121  and the second placement portion  122  are all the same size and shape. The placement portions  121  and  122  are circular recessed portions. The end portions  11   b  and  11   c  of the first type of nut  11 , as well as the first end portion  12   b  of the second type of nut  12 , are able to fit into the placement portions  121  and  122 . 
         [0031]    The plurality of mounting members  111  and  112  are formed by a first mounting member  111  for the first type of nut  11 , and a second mounting member  112  for the second type of nut  12 . In the insert molding apparatus  100 , there are three of the first mounting members  111 , and one of the second mounting member  112 . 
         [0032]      FIG. 4  is a perspective view of one of the first mounting members  111 . Hereinafter, the first mounting members  111  and other portions may be referred to in the singular to simplify the description.  FIG. 4  shows the first mounting member  111  upside down from the state in which it is shown in  FIG. 3 .  FIG. 5  is a side view of a state in which the first mounting member  111  is attached to the second type of nut  12  arranged on the first placement portion  121  in the insert molding apparatus  100 . The first mounting member  111  is mounted onto the first type of nut  11  that is assembled to the first placement portion  121 , before molten resin is injected into the forming die  101 . The first mounting member  111  holds down the first type of nut  11  using restoring force of an elastic member  108  (e.g., an elastic spring) attached to the first mounting member  111 . 
         [0033]    The first mounting member  111  includes a disk-shaped main body portion  111   a  that is pressed against the end surface of the first type of nut  11 , and a cylindrical peripheral wall portion  111   b  that rises from the main body portion  111   a , as shown in  FIG. 4 . The main body portion  111   a  and the peripheral wall portion  111   b  are integrated together. An inner diameter of the peripheral wall portion  111   b  is set so as able to fit the end portions  11   b  and  11   c  of the first type of nut  11 , but not able to fit the second end portion  12   c  (i.e., the end portion that is part of the knurled portion  12   a ) of the second type of nut  12 . More specifically, the inner diameter of the peripheral wall portion  111   b  is larger than the outer diameter of the end portions  11   b  and  11   c  of the first type of nut  11 , and smaller than the outer diameter of the second end portion  12   c  of the second type of nut  12 . When the main body portion  111   a  is pressed against the end surfaced of the first type of nut  11  by the elastic member  108 , the peripheral wall portion  111   b  is positioned on the outside of the outer peripheral surface of the end portion  11   c  of the first type of nut  11 . 
         [0034]    Notches  111   c  are formed from a tip end side in the peripheral wall portion  111   b . The depth of the notches  111   c  is lower than the height of the peripheral wall portion  111   b . In this example embodiment, there are two notches  111   c , but there may also be only one notch  111   c  or three or more notches  111   c . Also, the depth of the notches  111   c  may be equal to the height of the peripheral wall portion  111   b.    
         [0035]    The second mounting member  112  is formed in a disk-shape. An outer diameter of the second mounting member  112  is larger than an outer diameter of the second end portion  12   c  of the second type of nut  12 . The second mounting member  112  is mounted onto the second type of nut  12  that is assembled to the second placement portion  122 , before molten resin is injected into the forming die  101 . The second mounting member  112  holds down the second type of nut  12  via the bus bar  15 , using restoring force of an elastic member  109  (e.g., an elastic spring) attached to the second mounting member  112 . 
         [0036]    According to the structure described above, when the first type of nut  11  is attached to the first placement portion  121 , an inside surface of the main body portion  111   a  of the first mounting member  111  contacts the end surface of the first type of nut  11 , as shown in  FIG. 3 . On the other hand, when the second type of nut  12  is attached to the first placement portion  121 , a tip end surface of the peripheral wall portion  111   b  of the first mounting member  111  contacts the end surface of the second type of nut  12 , as shown in  FIG. 5 . As a result, a gap for detecting wrong assembly (hereinafter, simply referred to as a “wrong-assembly detection gap”)  135  is formed between the inside surface of the main body portion  111   a  of the first mounting member  111  and the end surface of the second type of nut  12 . This wrong-assembly detection gap  135  is connected via the notches  111   c  to a space inside the forming die  101  that is injected with molten resin. In the insert molding apparatus  100 , the wrong-assembly detection gap  135  that is connected via the notches  111   c  to the space inside the forming die  101  that is injected with molten resin is formed to the inside of the peripheral wall portion  111   b  only when the second type of nut  12 , from among the first type of nut  11  and the second type of nut  12 , is assembled to the first placement portion  121 . 
       Insert Molding Method  
       [0037]    Continuing on, an insert molding method using the insert molding apparatus  100  will be described. Hereinafter, a case in which the insert nuts  11  and  12  are correctly assembled will be described. 
         [0038]    With this insert molding method, an placement process is performed in which the insert nuts  11  and  12  are arranged on the first placement portion  121  provided in three locations and the second placement portion  122  provided in one location on the bottom surface of the lower die  103  of the forming die  101 . The first end portion  11   b  (or the second end portion  11   c ) of each of the first type of nuts  11  is fitted into the corresponding first placement portion  121 . The first end portion  12   b  of the second type of nut  12  is fitted into the second placement portion  122 . In this placement process, insert parts other than the insert nuts  11  and  12  are also assembled. The bus bar  15  is assembled in a predetermined position of the forming die  101  such that one end of the bus bar  15  overlaps with the upper surface of the second type of nut  12 . 
         [0039]    Continuing on, a die-closing process in which the upper die  102  is mounted onto the lower die  103  is performed. In this die-closing process, the first mounting member  111  is mounted onto the first type of nut  11 , and the second mounting member  112  is mounted onto the second type of nut  12 . In the closed forming die  101 , the first mounting member  111  holds down the second end portion  11   c  (or the first end portion  11   b ) of the first type of nut  11 , and the second mounting member  112  holds down the second end portion  12   c  of the second type of nut  12 . 
         [0040]    Next, an injection process in which a nozzle of the resin injecting device  104  is inserted into the fill port  110  and molten resin is injected into the forming die  101  from the resin injecting device  104  is performed. During this injection process, the position of the first type of nut  11  is maintained by the first mounting member  111 , and the position of the second type of nut  12  is maintained by the second mounting member  112 . Also, molten resin flows into the notches  111   c  of the peripheral wall portion  111   b  of the first mounting member  111 . 
         [0041]    After the injection process, a setting process in which the molten resin in the forming die  101  is set (i.e., solidified) is performed. Then after the resin in the forming die  101  has set, a die-opening process in which the forming die  101  is opened so that the upper die  102  separates from the lower die  103  is performed. In this die-opening process, the first mounting member  111  is removed from the first type of nut  11 , and the first type of nut  11  is released from the state in which it is held down by the first mounting member  111 . Also, the second type of nut  12  is also released from the state in which it is held down by the second mounting member  112 . The insert molded article  10  shown in  FIG. 1  is completed by performing the processes described above and the like. 
         [0042]      FIG. 6  is a perspective view of a corner portion of the insert molded article  10  when the insert nuts  11  and  12  are not wrongly assembled (i.e., when the insert nuts  11  and  12  are assembled correctly). In the insert molded article  10 , a portion of the second end portion  11   c  (or the first end portion  11   b ) of the first type of nut  11  is an exposed portion that is exposed on the outside. As shown in  FIG. 6 , the recessed portion  130  is formed as an impression of the peripheral wall portion  111   b  of the first mounting member  111  that is mounted to the first type of nut  11  when insert molding is performed. Furthermore, two of the protruding portions  131  that protrude from the bottom surface of the recessed portion  130  are formed as impressions of the two notches  111   c  formed in the peripheral wall portion  111   b . The recessed portion  130  is a generally circular groove. The protruding portions  131  are protrusions that are generally rectangular when viewed from above. 
         [0043]    Here, the diameter of the inside of the recessed portion  130  is equal to the inner diameter of the peripheral wall portion  111   b  of the first mounting member  111 . Therefore, the inner diameter of the peripheral wall portion  111   b  can be known based on the shape and dimensions of the recessed portion  130 , even without looking at the insert molding apparatus  100 . On the other hand, the diameter of the inside of the recessed portion  130  is smaller than the outer diameter of the second end portion  12   c  of the second type of nut  12  that is embedded in the insert molded article  10 . The shape and dimensions of the recessed portion  130  indicate that if the second type of nut  12  were to be arranged on the first placement portion  121 , the tip end surface of the peripheral wall portion  111   b  would contact the end surface of the second end portion  12   c  of the second type of nut  12  without the second end portion  12   c  of the second type of nut  12  fitting together with the peripheral wall portion  111   b , such that the wrong-assembly detection gap  135  would be formed to the inside of the peripheral wall portion  111   b . Also, the shape and dimensions of the protruding portion  131  correspond to the notches  111   c  in the peripheral wall portion  111   b . Therefore, the shape and dimensions of the notches  111   c  in the peripheral wall portion  111   b  are able to be known even without looking at the insert molding apparatus  100 . The shape and dimensions of the recessed portion  130  indicate that the wrong-assembly detection gap  135  is connected via the notches  111   c  to the space into which the molten resin is injected. 
       Method for Detecting Wrong Assembly of an Insert Nut  
       [0044]    Continuing on, a method for detecting wrong assembly when the insert nuts  11  and  12  are wrongly assembled in the placement process of the insert molding method will be described.  FIG. 7  is a perspective view of a corner portion of the insert molded article  10  when the insert nuts  11  and  12  are wrongly assembled. Hereinafter, a case will be described in which the second type of nut  12  is mistakenly assembled to the first placement portion  121  to which the first type of nut  11  should be assembled. 
         [0045]    In this case, in the placement process, the first end portion  12   b  of the second type of nut  12  is fitted into the first placement portion  121 . In this state, even if a worker looks at the second type of nut  12  that is wrongly assembled, the height and outer diameter of the end portion of the second type of nut  12  are only slightly different than they are with the first type of nut  11 , so the worker may not notice the wrong assembly. Then the first mounting member  111  will be mounted to the second end portion  12   c  of the second type of nut  12 . 
         [0046]    However, as described above, the inner diameter of the peripheral wall portion  111   b  of the first mounting member  111  is set such that the second end portion  12   c  of the second type of nut  12  is unable to fit. Therefore, in the injection process, the tip end surface of the peripheral wall portion  111   b  of the first mounting member  111  contacts the end surface of the second end portion  12   c  of the second type of nut  12 , and the first mounting member  111  rides on the second type of nut  12 , as shown in  FIG. 5 . The wrong-assembly detection gap  135  is formed between the main body portion  111   a  of the first mounting member  111  and the end surface of the second end portion  12   c  of the second type of nut  12 . The wrong-assembly detection gap  135  is connected via the notches  111   c  to the space inside the forming die  101  into which molten resin is injected. Therefore, molten resin that has been injected into the forming die  101  when the injection process is performed flows inside the second type of nut  12  and the wrong-assembly detection gap  135  through the notches  111   c . The wrong-assembly detection gap  135  is filled with molten resin. As a result, in the insert molded article  10  after the die-opening process, the end surface of the second end portion  12   c  of the second type of nut  12  is covered by resin  136 , as shown in  FIG. 7 . Also, the recessed portion  130  that forms when the first type of nut  11  is assembled to the first placement portion  121  will not form around the second type of nut  12 . When the end surface of the second end portion  12   c  of the second type of nut  12  is covered by the resin  136 , a worker is easily able to visually notice it. Also, whether the end surface of the second end portion  12   c  of the second type of nut  12  is covered is also able to be easily determined using an imaging device such as a camera. Therefore, wrong assembly of the insert nuts  11  and  12  is able to be easily detected. 
         [0047]    When the first type of nut  11  is wrongly assembled to the second placement portion  122 , the first type of nut  11  is higher than the second type of nut  12 , so the bus bar  15  will bend when it (i.e., the bus bar  15 ) is mounted to the upper side of the first type of nut  11 . Therefore, wrong assembly can be detected relatively easily when the placement process is performed. 
       Other Example Embodiments  
       [0048]    The example embodiment described above may also be structured as follows. 
         [0049]    In the example embodiment described above, both the shape and size of different types of specific insert parts (i.e., insert nuts) are different. However, it is sufficient that at least one of the shape and the size be different among different types of specific insert parts. 
         [0050]    Also, in this example embodiment, the peripheral wall portion  111   b  is formed along the entire periphery of the first mounting member  111 , but the peripheral wall portion  111   b  may also be formed on only a portion of the first mounting member  111  as long as the wrong-assembly detection gap  135  is formed by the tip end surface of the peripheral wall portion  111   b  abutting against the end surface of the second end portion  12   c  of the second type of nut  12 . In this case, the notches  111   c  may be cut out from the side instead of the tip end of the peripheral wall portion  111   b . Further, the notches  111   c  need only to connect the wrong-assembly detection gap  135  to the space into which molten resin is injected from outside of the forming die  101 . That is, a hole through the first mounting member  111  or a cutout formed along the peripheral wall portion  111   b  on the wrong-assembly detection gap  135  side of the peripheral wall portion  111   b  or the like may be used instead of the notches  111   c.    
         [0051]    Also, in the example embodiment described above, the insert molded article may be a resin molded article other than a case for an electronic control unit (ECU). 
         [0052]    Also, in this example embodiment described above, the specific insert parts for which a plurality of types of parts are used may be parts (e.g., rod-shaped parts) other than insert nuts. 
         [0053]    The invention may be applied to an insert molded article in which a plurality of types of parts are used for specific insert parts, an insert molding method for manufacturing this insert molded article, and an insert molding apparatus used in this insert molding method, and the like.