Abstract:
A blind rivet having sealing and water-tightness features. The blind rivet is fastenable to a member having an opening and includes a rivet body and mandrel. The rivet body has a flange having a large diameter, a taper portion which is adjacent the flange and a sleeve which extends along the axial direction from the taper portion. A hole having a bottom is formed from the surface of the flange to the bottom of the sleeve. The mandrel has a head. The head of the mandrel is disposed at the bottom portion of the hole. A thick portion is formed at a portion of the sleeve, and thus the head is irremovably held in the hole. The mandrel is pulled, the sleeve is enlarged, and a substrate is sealed between the enlarged portion and the flange. A sealing structure using the blind rivet is also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT/JP2013/077150, filed Oct. 4, 2013 which claims priority from Japanese Patent Application No. 2012-240006, filed Oct. 31, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention concerns a blind rivet. In particular, it concerns a blind rivet and sealing structure using same that has a taper on the reverse side of the blind rivet with a high degree of mounting stress and can achieve sufficient water tightness with a single blind rivet. 
       BACKGROUND ART 
       [0003]    Blind rivets that are provided with a metal rivet main body having a sleeve and a flange on one end of the sleeve, a head and a metal mandrel having a shaft extending from the head, are well known. An advantage of a blind rivet is that it can connect to a plurality of panels by working from just one side. 
         [0004]    A user would expect sufficient sealing and a high degree of water tightness between the rivet and the base body such as a panel (the attached member) after the blind rivet is fastened. 
         [0005]    There are two types of blind rivets. One is a sealed type in which the head of the mandrel, which causes the rivet main body to change when fastening, is set in the middle of the rivet, and the remaining head of the mandrel is not exposed to the blind side opposite the working side after fastening to the base body. The other is an open type in which the head of the mandrel sticks out of the rivet, and the remaining head of the mandrel is exposed to the blind side after fastening to the base body. 
         [0006]    The open type of blind rivet is not sufficiently watertight; it is easy for liquid to seep between the rivet main body and the remaining head of the mandrel because the remaining head of the mandrel is exposed after fastening. The sealed type of blind rivet has excellent water tightness; after fastening, it is more difficult for liquid to seep compared to the valved type, because only the rivet main body is exposed to the blind side after fastening. 
         [0007]    Kokai 2012-9288 discloses a sealing device consisting of a sealed type blind rivet, which seals the opening of a sealed rechargeable battery, and a resinous sleeve. The sealing device is provided with a metal core having a shaft and a large-diameter part, a flange bottomed metallic cylindrical member and a flange bottomed resinous sleeve into which part of the metallic cylindrical member is inserted from the opening side. When the metal core is pulled out of the metallic cylindrical member, the metallic cylindrical member is modified by the large-diameter part expanding in a radial direction. The resinous sleeve, expanding in a radial direction by the change of the metallic cylindrical member, seals the opening of the sealed rechargeable battery. 
         [0008]    The sealing device of Kokai 2012-9288, while maintaining cohesion of the resinous sleeve and the battery contents, is able to hold a hermetic seal of the battery. However, because it uses a bottomed resinous sleeve besides a blind rivet, the number of parts will be many, and cost will be high. 
         [0009]    Kokai 2012-145167 discloses a shield type blind rivet consisting of a mandrel and a rivet. The mandrel has a large diameter head on one end in the shape of a round rod. The rivet has a rivet main body in which one end is closed in the shape of a cylinder, and on the other end of the rivet main body, there is a flange. The rivet has the mandrel set so that it cannot come out by sealing the head when positioning it on the closed end. The rivet main body has a taper whose exterior form gets gradually smaller toward one end from the part connecting with the flange. 
         [0010]    Because it has a taper, in the blind rivet of Kokai 2012-145167, the area of overlap to the hole for a plate rivet and the rivet main body becomes smaller and a high degree of water tightness can be attained. 
         [0011]    However, this taper is provided with a small angle on the rivet main body, because it is assumed that it will overlap the hole for the plate rivet; if the variability of the inner diameter of the hole for the plate rivet is great, it is easy in the blind rivet of Kokai 2012-145167 for a part of the hole for the plate rivet not to overlap, and a high degree of water tightness cannot be attained at all. 
         [0012]    Kokai 2002-529663 discloses a blind rivet consisting of a head, an outer part in which a bottomed axial hole forms a shank extending from the head, a stem head and an inner part that has a stem disposed in the axial hole. The shank has a shank fastening part with a taper. 
         [0013]    The blind rivet of Kokai 2002-529663 has a problem with insufficient filling of the hole below the head, as the shank is actually mutually dependent on the work piece hole. 
         [0014]    However, the blind rivet of Patent Reference 3 is of the open type and, because the remainder part of the mandrel is exposed to the blind side, it is easy for leaking to occur between the rivet main body and the remainder part of the mandrel, so insufficient water tightness is an inherent problem with the open type. 
         [0015]    For this reason, we are seeking a blind rivet having a sufficient seal in the single blind rivet and a high degree of water tightness without the use of a washer or an O-ring. 
       SUMMARY OF THE INVENTION 
       [0016]    Thus, the object of the present invention is to provide a blind rivet that achieves a satisfactory seal with a single blind rivet. 
         [0017]    An additional object of the invention is to provide a sealing structure using this blind rivet. 
         [0018]    In order to achieve this object, the invention has a taper adjacent to the flange of the rivet main body of the blind rivet, the contact area of the edge of the opening of the base body and the back of the flange becomes small, the contact stress of the small contacting part is increased; this makes a secure seal. 
         [0019]    One embodiment of the invention is a blind rivet for fastening to a base body having an opening; it is provided with a rivet main body that has a disc-shaped large-diameter flange of a certain thickness, a taper with a gradually diminishing outer diameter that is separated at a distance from the flange and adjacent to it and a sleeve extending in an axial direction from the taper and in which a bottomed hole is formed from the surface of the sleeve to the bottom of the hole; there is also a mandrel having a head and a slender shaft that extends from the head with a smaller diameter than the head. The head of the mandrel is arranged at the bottom of the bottomed hole in the rivet main body; the shaft is combined so as to extend from the top surface of the flange of the rivet main body; in the sleeve of the rivet main body, a thick section with an inner diameter smaller than the outer diameter of the head is formed at a position adjacent to the head of the mandrel. The head is held by the thick section so that it cannot be moved from the bottomed hole of the rivet main body. 
         [0020]    This blind rivet is a sealed type with good sealing characteristics. Also, when there is a taper adjacent to the flange of the rivet main body, contact of the taper and the edge of the opening of the base body can be securely made. The disc-shaped flange of a certain thickness is rigid and difficult to deform. 
         [0021]    In the cross-section containing the central axis of the rivet main body, the angle of the taper surface of the taper and the straight line orthogonal to the central shaft of the blind rivet is 3-80°. 
         [0022]    An angle of 15-35° is preferable. 
         [0023]    When the taper inclines at this angle, the taper of the rivet main body and the edge of the opening of the base body can touch at an appropriate angle and make contact at an adequately narrow width. 
         [0024]    It is desirable that the thickness of the flange of the rivet main body be 15-75% of the outer diameter of the sleeve. 
         [0025]    The flange has sufficient thickness and rigidity, there is little deformation of the flange and the adjacent taper overall and a seal can be securely made at an adequately narrow width. 
         [0026]    It is desirable that the flange of the rivet main body be held and, when the shaft of the mandrel is pulled out, the material of the sleeve of the rivet main body is pushed outward by the head of the mandrel, expanding in diameter and a section with expanded diameter is formed. The base body is sandwiched between the section with expanded diameter of the rivet main body and the taper, and the rivet is fastened to the base body. 
         [0027]    It is desirable that a linear seal be formed between the taper and the edge of the top opening of the base body. 
         [0028]    The taper of the rivet main body and the edge of the opening of the base body securely make a metal seal at a narrow width. 
         [0029]    It is desirable for the mandrel, when fastened to the base body, to fracture at a small-diameter fracturing place of the shaft and the part from the fracturing part to the head to remain on the fastening part. 
         [0030]    An additional embodiment of the invention is a sealing construction that seals the opening of the base body; the construction is such that the top boundary of the opening forms an edge and, when the blind rivet is fastened to the opening, the taper and top edge of the opening are in contact and the opening is sealed. 
         [0031]    According to the invention, sufficient sealing characteristics are achieved with a single blind rivet, and a blind rivet with a high degree of watertightness is obtained. 
         [0032]    Also, a sealing construction that uses this blind rivet is obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is an upright view with a partial cross-section of the blind rivet of the first embodiment of the invention. 
           [0034]      FIG. 2  is an upright view with a partial cross-section showing the insertion of the blind rivet of  FIG. 1  into the opening of the base body. 
           [0035]      FIG. 3  is an upright view with a partial cross-section of the blind rivet of  FIG. 1  fastened to the base body. 
           [0036]      FIG. 4  is an upright view with a partial cross-section of a blind rivet of prior art with attached washer that is fastened to the base body. 
           [0037]      FIG. 5  is an upright view with a partial cross-section of a blind rivet of prior art without a taper that is fastened to the base body. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]    Below, the blind rivet according to the embodiments of the invention will be described. 
         [0039]      FIG. 1  is an upright view with a partial cross-section of the blind rivet of the first embodiment of the invention. In the description of the invention, the top of  FIG. 1  is the up direction, and the bottom is the down direction. The blind rivet  1  is provided with a rivet main body  10  and a mandrel  30 . A head  31  of the mandrel  30  and a part of a shaft are inserted into the bottomed hole  18  of the rivet main body  10  and fixed. 
       (Mandrel) 
       [0040]    The mandrel  30  has a head  31  at one end. The head  31  has the shape of a large-diameter disk. The mandrel  30  has a slender shaft that adjoins the head  31 . The shaft has a shaft base  32 , a fracturing part  33 , a small-diameter part  34 , a shaft part  35  and a gripping part  36 . The part adjacent to the head  31  of the shaft is the discoid shaft base  32  that has a smaller diameter than that of the head  31 . Adjacent to the shaft base  32  there is a fracturing part  33  that has a smaller diameter than that of the shaft base  32 . In assembling the blind rivet  1 , the fracturing part  33  is the part that is to be seated in the bottomed hole  18  of the rivet main body  10 . When the shaft of the mandrel  30  is pulled out with a fastening mechanism, a certain extraction force is added and the mandrel  30  breaks at the fracturing part  33 . 
         [0041]    Adjacent to the fracturing part  33 , there is a small-diameter part  34  with an outer diameter smaller than that of the fracturing part  33 . The diameter of the small-diameter part  34  is nearly equal to the diameter of the shaft base  32 . Adjacent to the small-diameter part  34 , there is a shaft part  35  of a slender cylindrical shape with a diameter larger than that of the small-diameter part  34  but smaller than that of the head  31 . Adjacent to the shaft part  35 , there is a gripping part  36  with nearly an equal diameter to that of the shaft part  35 . On the gripping part  36 , several engagement grooves are formed at regular intervals around the circumference so as not to cause slipping when gripped by the gripping member of the engagement mechanism. 
         [0042]    The material of the mandrel  30  is steel, aluminum, stainless steel, etc. and the material is harder than that of the rivet main body  10 . 
       (Rivet Main Body) 
       [0043]    The complete rivet main body  10  is of cylindrical shape and has a flange  16 , a taper  15  and a sleeve at one end. The other end of the sleeve is closed. The sleeve has a bottom  11 , a thin section  12 , a thick section  13  and a cylindrical part  14 . The end of sleeve, the other end, is the bottom  11 ; under the bottom  11  is a flat, round surface. Adjacent to the bottom  11 , there is thin section that surrounds the head  31  of the mandrel  30 . Adjacent to the thin section  12 , there is a thick section  13  that surrounds the shaft base  32 , the fracturing part  33  and the small-diameter part  34  of the mandrel  30 . Adjacent to the thick section  13 , there is a cylindrical part  14  that surrounds the shaft part  35  of the mandrel  30 . The outer diameter of the sleeve (thin section  12 , thick section  13  and cylindrical part  14 ) is roughly equal to the inner diameter of the opening  53  of the base body  51  or a little smaller, of a size that can be inserted into the opening  53 . 
         [0044]    The opening  53  of the base body  51  generally has a round cross-section and is a hole that has to be sealed. 
         [0045]    The top boundary of the opening  53  is formed in the shape of an edge, and a taper is not formed. 
         [0046]    Adjacent to the cylindrical part  14 , there is a taper  15  of a circular truncated cone shape. When the bottom  11  of the blind rivet  1  is inserted into the opening  53  of the base body  51  first, the part near the boundary of the cylindrical part  14  of the taper  15  contacting the edge of the opening is stopped. The angle between the cylindrical part  14  and the taper  15  suddenly changes without continuing as a curve. The diameter of the taper  15  tends to become larger from the cylindrical part  14  to the flange  16 . 
         [0047]    The taper  15 , being the angle α made by the central axis of the rivet main body  10  and the orthogonal surface, is 3-80°. That is, in the cross section containing the central axis of the rivet main body  10 , the straight line of the taper surface of the taper  15  and the straight line orthogonal to the central axis of the rivet main body  10  cross at an angle of 3-80° (the angle (90°-α) of the straight line of the taper surface and the central axis of the rivet main body is 20 [sic]-87°). Preferably, this angle α is 15-35°. 
         [0048]    Adjacent to the taper  15 , there is a large-diameter flange  16 . The top of the flange  16  is flat. The flange  16  is of a thick discoid shape, and its outer diameter is uniform from the top to the boundary of the taper  15 . The flange  16  has sufficient hardness. The thickness Tf of the flange  16  is 15-75% of the diameter Ds of the sleeve. Here, the dimensions Tf and Ds are the measurements when the rivet main body  10  and the mandrel  30  are assembled. 
         [0049]    The material of the rivet main body  10  is steel, aluminum, stainless steel, copper, etc. and is formed with a softer material than that of the mandrel  30 . 
         [0050]    On the inside of the rivet main body  10 , a bottomed hole  18  is formed that extends axially downward from the top of the flange  16 . The shaft base  32 , fracturing part  33  and part of the small-diameter part  34  are set into the bottomed hole  18  adjacent to the head  31  of the mandrel  30  above the bottom  11 . The head  31  of the mandrel  30 , the upper edge of which is pressed by the thick section ( 13 ) of the rivet main body  10 , will not come out. 
         [0051]    The inner diameter of the bottomed hole  18  of the rivet main body  10  before the mandrel  30  is inserted is to some extent of a large uniform diameter equal to the outer diameter of the head  31  of the mandrel  30 , and the head  31  can be inserted into the bottomed hole head first. The diameter of the sleeve (thin section  12 , thick section  13 , cylindrical part  14 ) of the rivet main body  10  before inserting the mandrel  30  is uniform. 
       (Blind Rivet) 
       [0052]    In the blind rivet assembled with a rivet main body  10  shown in  FIG. 1  and a mandrel  30 , the mandrel  30  is inserted into the bottomed hole of the rivet main body  10  with the head  31  going first. The head  31  of the mandrel  30  is inserted up to a position abutting the inner surface of the bottom  11 . In this situation, the inner circumference of the bottomed hole  18  and the head  31  are in close contact or have a tiny space between them. There is a space between the inner circumference of the bottomed hole  18 , the shaft base  32  of the mandrel  30 , the fracturing part  33  and the small diameter part  34 . 
         [0053]    After the mandrel  30  is inserted into the bottomed hole  18 , the sleeve part narrows to a uniform diameter from the bottom  11  up to the taper  15  by a rolling, fastening process or the like, and the material of the sleeve moves into the space between the inner circumference of the bottomed hole  18 , the shaft base  32  of the mandrel  30 , the fracturing part  33  and the small diameter part  34 . As shown in  FIG. 1 , there is no space between the inner circumference of the bottomed hole  18 , the shaft base  32  of the mandrel  30 , the fracturing part  33  and the small diameter part  34 . The shapes of the thick section  13  of the rivet main body  10  and cylindrical part  14  are then formed. 
         [0054]    Thus, the thick section  13  is in contact with the top of the head  31  and the head  31  can be extracted from the bottomed hole  18 . 
         [0055]      FIG. 2  is an upright view of a partial cross-section showing the situation where the blind rivet of  FIG. 1  is inserted into the opening  53  of the base body  51 . The lower side of  FIG. 2  is the blind side, and the operation of installing the blind rivet  1  is carried out from above. 
         [0056]    The base body  51  is one piece, but the base body  51  could be several pieces; in that case, the positions of the openings  53  of each base body  51  are superimposed to fit. 
         [0057]    When the blind rivet  1  of  FIG. 1 , assembled with a rivet main body  10  and a mandrel  30 , is inserted into the opening  53  of the base body  51  from the top in  FIG. 2 , the taper  15  of the rivet main body  10  abuts the surface around the opening  53  of the base body in the situation of  FIG. 2 . 
       (Fastening) 
       [0058]    In reference to  FIGS. 2 and 3 , fastening of the blind rivet  1  of the embodiment of the invention onto the base body  51  will be described. 
         [0059]    From the situation of  FIG. 2 , the top of the flange  16  of the rivet main body  10  is supported, and, when the gripping part  36  of the mandrel  30  is gripped by the gripping member of the fastening mechanism, it is drawn upward. The head  31  of the mandrel  30 , while expanding the thick section  13  of the rivet main body  10  from inside, moves up. The diameter of the thick section  13  and the cylindrical part  14  become larger with the expansion by the head  31  and the length of the thick section  13  and the cylindrical part  14  becomes smaller. By the change of the thick section  13  and the cylindrical part  14 , a section with enlarged diameter  21  is formed. The outer diameter of the section with enlarged diameter  21  becomes larger than the inner diameter of the opening  53 , and the inner diameter is nearly equal to the outer diameter of the head  31 . 
         [0060]    The part of the cylindrical part  14  inside the opening  53  of the base body  51  is checked by the opening and will not bulge. When the head  31  of the mandrel  30  approaches the base body  51 , the head  31 , not being able to expand the cylindrical part  14 , cannot rise above it. 
         [0061]    Moreover, when the gripping part  36  of the mandrel  30  draws upward, the mandrel  30  is broken at the fracturing part  33 . The head  31  and the shaft base  32  remain inside the rivet main body  10 , and the shaft  35  and the gripping part  36  are extracted from the bottomed hole  18  of the rivet main body  18 . Thus, the base body  51  is sandwiched between the section with enlarged diameter  21  of the rivet main body  10  and the taper  15  and the blind rivet  1  is fastened. 
         [0062]    Both the lower end of the taper  15  and the inner edge of the top of the opening  53  of the base body  51  are sealed by the stress at the narrow line. The upper boundary of the opening  53  of the base body  51  is formed in an edge, and a taper is not formed. Because of this, both the upper edge of the opening  53  and taper  15  of the rivet main body  10  will not be touching by a large width. 
         [0063]    Also, both the upper edge of the enlarged diameter portion  21  and the inner edge of the opening  52  below the base body  51  are sealed by high stress at the line with narrow width. Both the metal of the rivet main body  10  and the metal of the base body  51  are sealed in close contact. 
         [0064]    According to the embodiment of the invention, the taper  15  of the rivet main body  10  has a small area contacting the inner edge of the opening  53  of the base body  51  and is in contact by means of a strong stress. Because of this, the inner edge of the taper  15  or the opening  53  or both being in close contact through deformation are able to attain a seal and a high degree of watertightness. 
         [0065]    Also, with the blind rivet according to the embodiment of the invention and the opening  53  of the base body  51 , a sealing structure that seals the opening  53  of the base body  51  is formed. In this sealing structure, the upper border of the opening  53  is formed into an edge, and, in the situation where the blind rivet is fastened into the opening  53 , both the taper  15  and the upper edge of the opening  53  are in close contact and opening  53  is sealed. 
       (Comparison Example 1) 
       [0066]      FIG. 4  is a plan view of a partial cross-section after using a resinous washer  70  and the bottom of a flange of prior art fastening the level rivet main body  60  to the base body  51 . The mandrel  30  is the same as the mandrel  30  of the embodiment of the invention and is shown with the same reference number. The base body  51  is the same as the base body  51  used in the embodiment of the invention and is shown with the same reference number. The rivet main body  60  of Comparison Example 1 has a bottom  61 , a thin section  62 , a section with enlarged diameter  67 , a cylindrical part  64  inside the opening  53  and a flange  66 . 
         [0067]    The base body  51  is sandwiched between the section with enlarged diameter  67  of the rivet main body  60  and the washer  70 , and the blind rivet  6  is tightened to the base body  51 . 
         [0068]    After fastening the blind rivet  6  of Comparison Example  1 , between the back of the flange  66  and the top of the washer  70  and between the bottom of the washer  70  and the base body  51 , the contact surface is wide and the contact pressure between members is low so a sufficient seal cannot be attained. Also, a resinous washer  70  is necessary besides the blind rivet  6 , and the cost is increased. 
       (Comparison Example 2) 
       [0069]      FIG. 5  is a plan view of a partial cross-section when the bottom of the flange of prior art fastens the rivet main body  60 ′ of a top spherical surface evenly to the base body  51 . The mandrel  30  is the same as the mandrel  30  of the embodiment of the invention and is shown with the same reference number. The base body  51  is the same as the base body  51  used in the embodiment of the invention and is shown with the same reference number. The rivet main body  60 ′ has a bottom  61 ′, a thin section  62 ′, a section with enlarged diameter  67 ′, a cylindrical part  64 ′ inside the opening  53  and a flange  66 ′. 
         [0070]    The base body  51  is sandwiched between the enlarged diameter portion  67 ′ of the rivet main body  60 ′ and the flange  67 ′ and the blind rivet  6 ′ is fastened. 
         [0071]    After fastening the blind rivet  6 ′ of Comparison Example 2, between the back of the flange  66 ′ and the base body  51 , the contact surface is wide and the contact pressure between members is low so that a sufficient seal cannot be attained. 
         [0072]    Compared to comparison Examples 1 and 2, the blind rivet according to the embodiment of the invention has a taper under the flange, so by means of high stress in a small area, it contacts the edge of the opening of the base body. Because of this, sufficient sealing is attained with the single blind rivet, and a blind rivet with a high degree of watertightness can be achieved. 
         [0073]    Keys to Text in Drawings 
         [0074]      1  blind rivet 
         [0075]      6  blind rivet 
         [0076]      10  rivet main body 
         [0077]      11  bottom 
         [0078]      12  thin section 
         [0079]      13  thick section 
         [0080]      14  cylindrical part 
         [0081]      15  taper 
         [0082]      16  flange 
         [0083]      18  bottomed hole 
         [0084]      21  section with expanded diameter 
         [0085]      30  mandrel 
         [0086]      31  head 
         [0087]      32  shaft base 
         [0088]      33  fracturing part 
         [0089]      34  small-diameter part 
         [0090]      35  shaft 
         [0091]      36  gripping part 
         [0092]      51  base body 
         [0093]      53  opening 
         [0094]      60  rivet main body 
         [0095]      61  bottom 
         [0096]      66  section with expanded diameter 
         [0097]      70  washer