Abstract:
A blind rivet includes a hollow rivet body having a longitudinally extending indented groove. The groove may be shaped to impart rivet setting characteristics that may be varied to provide desirable fastening characteristics for joints in a number of industries. The shape of the indentation on the rivet body may be varied to cause a portion of the rivet body to collapse and form a secondary head at a predetermined longitudinal location.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 11/227,021, filed Sep. 15, 2005, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention generally relates to blind rivets and, more particularly, to pull-type blind rivets having a large secondary head. 
     A number of blind rivets have been manufactured that include a hollow rivet body with a flanged head on one end and an opposite open end. A mandrel is at least partially positioned within the hollow rivet body and includes an enlarged head positioned adjacent the open end of the rivet body. The rivet body may be inserted into openings formed into workpieces that are to be joined to one another. The flanged head of the rivet body is positioned in engagement with a surface of one of the workpieces. A nose piece of a rivet setting tool is placed against the flanged head of the rivet body. The rivet setting tool includes a mechanism for pulling the mandrel. As the pulling mechanism pulls the mandrel, a portion of the rivet body between the mandrel head and the workpieces is collapsed on the opposite side of the far workpiece to form a secondary head on the rivet body to secure the rivet to the workpieces. This process is generally known in the art as “setting” the rivet. The rivet setting tool continues to pull the mandrel until the mandrel breaks at a predetermined point and at a predetermined break load thus leaving a portion of the mandrel within the set rivet body. At this time, the rivet is secured in the opening of the workpieces with the flanged head of the rivet body against a surface of one workpiece facing the operator performing the rivet setting operation and a formed secondary head against a surface of the other workpiece remote from the operator that is usually termed the “blind-side” surface. 
     Pull-type rivets have typically been used to join thin, soft or fragile materials to one another where access to only one surface is available. For example, brackets have been attached to foam insulated panels and thin metallic sheets have been coupled to one another using blind rivets. Accordingly, it should be appreciated that the demands of these industries are varied and that the product construction may need to be adjusted to suit the different requirements of each joint to be created and to give a reliable setting in each case. For instance, it may be desirable to reliably position the larger secondary head closer to the mandrel head in one application while in another application it may be desirable to reliably position the larger secondary head adjacent the flanged head of the rivet body. This joint design flexibility and reliability is not presently available in the known blind fastener art. 
     In addition, many of the applications using blind rivets include exposure to the elements on occasions where the relative humidity of the environment is high. In these applications, it may be necessary to prevent ingress of moisture past the head of the rivet after it has been set. Joint deterioration and structural damage may occur if the moisture is allowed to travel past the flanged head of the rivet body. Accordingly, it may be beneficial to provide a blind rivet having a means for sealing the flanged head of the rivet body against the workpiece and for the retained mandrel to seal within the bore of the rivet body. 
     The blind rivet of the present invention includes a rivet body having a longitudinally extending indented groove. The groove may be formed to define different shapes to impart different rivet setting characteristics that may be varied to provide optimum fastening characteristics to a variety of joints in a number of industries. For example, the shape of the indentation on the rivet body may be varied to cause a portion of the rivet body to collapse and form the secondary head adjacent to the flanged head on the end of the rivet body. A differently shaped indentation formed on the rivet body causes the rivet body to collapse and form the secondary head near the mandrel head. 
     In another feature, the rivet body is formed prior to setting to have a barrel-shaped shank positioned between the flanged head and the open end of the rivet body. The barrel shape significantly lowers the initial upset load that is needed to commence formation of the secondary head. 
     Furthermore, the rivet may include four indentations or slots circumferentially spaced apart from one another on the hollow rivet body. In this manner, four collapsed legs are formed during rivet setting. By creating four legs instead of the three legs shown in the prior art, the setting load is lower and allows the potential use of higher strength rivet materials resulting in higher tensile and shear strength. 
     Additionally, the blind rivet of the present invention includes a feature where the mandrel is coupled to the rivet body to allow shipping and handling of the rivet prior to setting as well as providing a feature for maintaining a portion of the mandrel within the rivet body after the setting procedure has been completed. A plurality of indentations are formed in the rivet body such that portions of the rivet body are displaced into a recess or recesses formed on the mandrel adjacent the mandrel head. 
     In addition, the blind rivet includes a seal positioned between the flanged head of the rivet body and the workpiece to prevent ingress of moisture or contamination around the set rivet. The rivet is further sealed by retaining a portion of the mandrel with the hollow body and causing the flange of the rivet body to engage the mandrel and one or more grooves. Lastly, the rivet body flange may be shaped such that it may accept a cover or cap. The cap may be colored to match or complement the colors of the individual workpiece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is perspective view of an exemplary blind rivet of the present invention; 
         FIG. 2  is the side view of the blind rivet as shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  as shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the blind rivet taken along line  44  as shown in  FIG. 3 ; 
         FIG. 4A  is a cross-sectional view of an alternate embodiment blind rivet taken along a line similar to line  44  of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of an alternate embodiment blind rivet taken along a line similar to line  3 - 3  of  FIG. 2 ; 
         FIG. 6  is a side view of a mandrel separated from the blind rivet body; 
         FIG. 7  is a cross-sectional view of the mandrel taken along line  6 - 6  shown in  FIG. 6 ; 
         FIG. 8  is a perspective view of a blind rivet after the setting process has been completed; 
         FIG. 9  is an end view of the blind rivet shown in  FIG. 8 ; 
         FIG. 10  is an opposite end view of the blind rivet shown in  FIG. 8 ; 
         FIG. 11  is a cross-sectional side view of the blind rivet taken along line  11 - 11  as shown in  FIG. 9 ; 
         FIG. 12  is a cross-sectional view of the blind rivet taken along line  12 - 12  as shown in  FIG. 10 ; 
         FIG. 13  is a cross-sectional side view of the blind rivet installed in an exemplary joint; 
         FIG. 14  is a side view of an alternate embodiment blind rivet; 
         FIG. 15  is a cross-sectional view taken along line  15 - 15  as shown in  FIG. 14 ; 
         FIG. 16  is a cross-sectional view taken along line  16 - 16  as shown in  FIG. 15 ; 
         FIG. 17  is a side-view of another alternate embodiment blind rivet; 
         FIG. 18  is a cross-sectional view taken along line  18 - 18  as shown in  FIG. 17 ; 
         FIG. 19  is a cross-sectional view of the blind rivet taken along line  19 - 19  as shown in  FIG. 18 ; 
         FIG. 20  is a side view of another alternate embodiment blind rivet; 
         FIG. 21  is a cross-sectional view taken along line  21 - 21  as shown in  FIG. 20 ; 
         FIG. 22  is a cross-sectional view taken along line  22 - 22  as shown in  FIG. 21 ; 
         FIG. 23  is a side view of another alternate exemplary blind rivet; 
         FIG. 24  is a cross-sectional view taken along line  24 - 24  as shown in  FIG. 23 ; 
         FIG. 25  is a cross-sectional view taken along line  25 - 25  as shown in  FIG. 24 ; 
         FIG. 26  is a cross-sectional view of the blind rivet shown in  FIG. 23  after the rivet setting process has been completed; 
         FIG. 27  is a side view of another alternate embodiment blind rivet; 
         FIG. 28  is another side view of the alternate embodiment blind rivet shown in  FIG. 27 ; and 
         FIG. 29  is a cross-sectional side view depicting another alternate embodiment blind rivet embodiment shown after the completion of the rivet setting process and installation of a cap. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
       FIGS. 1-4  and  6 - 13  relate to a first embodiment blind rivet  10  having a substantially cylindrical hollow rivet body  12  and a mandrel  14  coupled to rivet body  12 . Rivet body  12  includes a flanged head  16  at one end. The flanged head  16  radially extends substantially perpendicular to the longitudinal axis  18  passing through the center of rivet body  12 . Flanged head  16  includes a substantially planar first surface  20  and a concave second surface  22 . 
     Rivet body  12  is substantially cylindrically shaped having an outer surface  24  and an inner cylindrical surface  26 . Inner surface  26  is substantially smooth with no outwardly extending projections formed thereon. 
     Four circumferentially spaced apart indentations  28  are formed on outer surface  24  of rivet body  12 . Each indentation  28  includes a slit or a cut  30  extending through the hollow rivet body  12 . 
     Each indentation  28  includes a first longitudinally extending surface  32  and a second longitudinally surface  34 . Each of surfaces  32  and  34  terminate at slit  30 . First longitudinally extending surface  32  is also bounded by a longitudinally extending edge  36  that defines the interconnection between substantially planar longitudinally extending surface  32  and cylindrical outer surface  24 . Second longitudinally extending surface  34  meets cylindrical surface  24  at an edge  38 . The ends of slit  30  and longitudinally extending surfaces  32  and  34  are bounded by angled end surfaces  40  and  42 . In the embodiment shown in  FIG. 2 , edge  36 , edge  38  and slit  30  are substantially linear segments positioned substantially parallel to one another. Each of surfaces  32  and  34  are substantially planar and define an included angle ranging between 20 and 90 degrees. Surfaces  40  and  42  are also substantially planar.  FIG. 5  depicts an alternate embodiment rivet body  12 ′ including curved surfaces  32 ′ and  34 ′. The surfaces  32 ′ and  34 ′ are curved in a laterally extending direction. 
     Returning to the embodiment depicted in  FIGS. 1-4  and  6 - 13 , rivet body  12  includes a plurality of column portions  43  circumferentially spaced apart from one another. Each column portion  43  is positioned between two of indentations  28 . As best shown in  FIG. 4 , column portions  43  have a bowed shape prior to rivet setting. The bowed shape defines a maximum outer diameter at approximately the longitudinal mid-point of longitudinally extending slit  30 . The bulged shape greatly reduces the initial tensile load required to be placed on mandrel  14  to begin to cause deformation of columns  43 . By reducing the load required to buckle column portions  43 , it is possible to increase the material strength of the rivet body to provide greater clamping force between flanged head  16  and the secondary head formed during rivet setting. It is contemplated that rivet body  12  may be constructed from a relatively high grade aluminum or possibly stainless steel to provide the desired joint clamp load and provide a greater resistance to applied forces pulling the joined materials apart. 
       FIG. 4A  depicts an alternate embodiment blind rivet  10 ′. Rivet  10 ′ is substantially similar to rivet  10  except that rivet body  12  has been modified to have an enlarged diameter portion  24 ′ positioned adjacent flanged head  16 . Accordingly, like elements will retain their previously introduced reference numerals. Enlarged diameter portion  24 ′ axially extends a distance “X” from first surface  20  of flanged head  16 . Distance “X” represents a minimum grip length for the particular rivet design. As such, the sum of the material thicknesses to be joined to one another by blind rivet  10 ′ preferably equals or exceeds the minimum grip length. Furthermore, enlarged diameter portion  24 ′ has an outer diameter of approximately the same size as the maximum outer diameter defined by the bulged shape of column portions  43 . 
     With reference to the first embodiment shown in  FIGS. 1-4  and  6 - 13 , a second plurality of indentations  44  are formed in rivet body  12  near the open end. Second indentations  44  function to retain mandrel  14  within rivet body  12  during shipping and handling, prior to setting. Second indentations  44  also retain the portion of the mandrel that remains within the rivet body after setting. Mandrel  14  includes a plurality of indentations  46  in receipt of a portion of the upset material of rivet body  12  that is radially inwardly deformed during formation of second indentations  44 . 
     Mandrel  14  includes a substantially cylindrical body  48  having a first end  50  and a second end  52 . First end  50  includes a reduced diameter portion  54  that provides a locating function to ease insertion of mandrel  14  within a rivet setting tool. Second end  52  includes an enlarged head  56  having a bottom face  58  and a substantially spherical outer surface  60 . The shape of outer surface  60  may also be substantially conical or otherwise tapered to facilitate insertion of blind rivet  10  within an aperture formed in a workpiece. Bottom face  58  is substantially planar and configured to engage a substantially planar end face  62  formed on the open end of rivet body  12 . 
     As mentioned earlier, mandrel  14  includes an indentation  46  to retain mandrel  14  to rivet body  12 . Mandrel  14  also includes a groove  64  extending about the circumference of body  48  axially spaced apart from indentation  46 . Groove  64  provides a reduced cross-sectional area of mandrel at which the mandrel separates during the setting process. Indentation  46  and/or groove  64  may be shaped as a cylindrical surface or as a plurality of localized planar portions defining a reduced cross-sectional area as shown in  FIGS. 6 and 7 . Specifically, four flats  66  are formed on mandrel body  48  to define a reduced cross-sectional area  68 . Upon input of sufficient tensile load applied by the rivet setting tool, a first portion  70  of mandrel  14  will detach from a second portion  72 . First portion  70  is positioned on an opposite side of reduced cross-sectional area  68  as second portion  72 . Similarly, flats  74  are formed at four circumferentially spaced apart locations adjacent head  56  to define indentation  46  and provide clearance for the material upset during the formation of second indentations  44 . Between flats  74  and flats  66  is a section  73  that is of uniform diameter that provides resistance to ingress of moisture when the rivet is set by having a tight or interference fit in the rivet body  12  at the location  75  ( FIG. 12 ) adjacent to the flange  16 . 
       FIGS. 8-13  depict blind rivet  10  in a set state. During the rivet setting process, tensile force is applied to first end  50  of mandrel  14  after the blind rivet has been inserted within aligned apertures of the workpieces to be joined.  FIG. 13  depicts an exemplary application for blind rivet  10  where a workpiece  76  includes an aperture  78  while another workpiece  80  includes an aperture  82 . The blind rivet, prior to setting, is inserted through apertures  78  and  82  until first planar surface  20  of rivet body contacts a work surface  84  of workpiece  76 . As tensile force is added to mandrel  14 , flanged head  16  of rivet body  12  is maintained in contact with surface  84  of workpiece  76 . During the setting process, head  56  of mandrel  14  is drawn into engagement with the rivet body  12 . Specifically, bottom face  58  of mandrel  14  acts upon end face  62  of rivet body  12 . As the rivet tool continues to apply tensile force to mandrel  14 , a compressive force between flanged head  16  of rivet body  12  and head  56  of mandrel  14  increases until column portions  43  of rivet body  12  positioned between indentations  28  begin to buckle. 
     Upon completion of the rivet setting process, each column portion  43  is folded upon itself to form a leg  86 . Based on the positioning of the indentations  28 , four circumferentially spaced, laterally extending legs  86  are formed. Each leg includes a first laterally outwardly extending portion  88  and a laterally inwardly returning portion  90 . The equally spaced legs  86  collectively define a secondary head  92  axially spaced apart from flanged head  16 . Each leg  86  laterally extends from longitudinal axis  18  a distance greater than the flanged head  16 . It should be appreciated that the axial positioning and length of slit  30  define the size of legs  86  and the distance between surface  20  of flanged head  16  and a clamping surface  94  formed on each leg  86 .  FIG. 13  shows that uniform diameter section  73  provides resistance to ingress of moisture when the rivet is set by having a tight or interference fit in the rivet body  12  at the location  75  adjacent to the flange  16 . 
       FIGS. 14-16  depict an alternate embodiment blind rivet  100 . Alternate embodiment blind rivet is substantially similar to blind rivet  10  except that blind rivet  100  includes oval shaped indentations  102  in lieu of indentations  28 . Accordingly, like elements will retain their previously introduced reference numerals. 
     Indentation  102  is substantially oval-shaped having a maximum width at its axial midpoint. Indentation  102  includes a first substantially planar surface  104  and a second substantially planar surface  106 . A cut or slit  108  extends through rivet body  12  and longitudinally extends between surfaces  104  and  106 . End surfaces  110  and  112  slope downwardly from outer cylindrical surface  24  of rivet body  12  toward slit  108 . Two boundary edges of the end surfaces are defined by surfaces  104  and  106  and a third edge is defined by the body surface  24 . These surfaces form the shape of the indentation  102  at each end of the slit. Four column portions  114  are circumferentially spaced apart from one another such that each column  114  is positioned between two indentations  102 . Column portions  114  are outwardly bulged having a maximum diameter axially aligned with the maximum width of indentation  102 . Because the maximum width of indentation  102  is found at the midpoint of the axial length of slit  108 , the minimum wall thickness of portion  114  is also positioned at the axial midpoint of slit  108 . The aforementioned geometry causes a maximum stress condition to occur at the axial midpoint of slit  108  during the rivet setting process. In this manner, legs  86  may be repeatably formed because the minimum wall thickness location defines the axial position at which the portions  114  will buckle during compressive loading. 
       FIGS. 17-19  depict another alternate embodiment blind rivet  150 . Blind rivet  150  is substantially similar to blind rivet  100  and blind rivet  10  except that the shape of the indentations having a slit have been modified. As such, like elements will retain their previously introduced reference numerals. Blind rivet  150  includes four circumferentially spaced apart indentations  152 . Each indentation  152  has a substantially teardrop shape having a maximum width located at an axial position closer to flanged head  16  than mandrel head  56 . The maximum width of the indentation is offset from the axial midpoint of a cut or slit  154  extending through rivet body  12 . A first substantially planar surface  156  and a second substantially planar surface  158  are angled inwardly from outer cylindrical surface  24  of rivet body  12 . Slit  154  terminates at end surfaces  160  and  162 . In similar fashion to the end surfaces previously described, end surfaces  160  and  162  are substantially planar angled surfaces extending from outer cylindrical surface  24  to inner surface  26 . 
     Four columns of material  164  are defined and positioned between each of indentations  152 . The minimum cross section of each column  164  is axially positioned at the widest point of indentation  152 . The columns  164  are outwardly bulged and define a maximum outer diameter at the axial position where each indentation  152  has its maximum width. Because the widest point of indentation  152  is positioned relatively closer to flanged head  16 , the distance between surface  20  of flanged head  16  and surface  94  of secondary head  92  may be tailored to be a desired distance based on the location of the maximum width of indentation  152 . Accordingly, a family of blind rivets may be designed where each member of the family defines a different distance between the secondary head and flanged head  16 . Each member will be operable to clamp workpieces having different joint thicknesses. 
       FIGS. 20-22  depict another alternate embodiment blind rivet identified at reference numeral  200 . Blind rivet  200  is substantially similar to the blind rivets previously described. For clarity, like elements will retain their previously introduced reference numerals. 
     Blind rivet  200  includes four indentations  202  circumferentially spaced apart from one another. Each indentation  202  includes a first substantially planar surface  204  and a second substantially planar surface  206  bounded by a common cut  208 . First surface  204  includes a substantially linear first edge  210  and a substantially linear second edge  212 . First edge  210  and second edge  212  meet at a relatively sharp inflection point  214 . Second surface  206  is substantially similarly shaped as first surface  204 . The width of indentation  202  is at its maximum at the axial location of inflection point  214 . The cross-sectional width of column portions  216  positioned between indentations  202  are at their minimum at the longitudinal location of inflection point  214 . Furthermore, column portions  216  are outwardly bulged and define a maximum outer diameter at the axial position of inflection point  214 . Therefore, when a compressive load is applied to the walls of rivet body  12 , buckling begins at the point of minimum wall section and a secondary flange (not shown) will be formed proximate flanged head  16 . 
       FIGS. 23-26  depict another alternate embodiment blind rivet identified at reference numeral  250 . Blind rivet  250  is substantially similar to the blind rivets previously described except that the indentations with longitudinally extending slits have been replaced with longitudinally extending slots  252 . Like elements will retain their previously introduced reference numerals. 
     Each slot  252  extends longitudinally parallel to axis  18  and radially through rivet body  12 . Each slot  252  is defined by a first side wall  254  and a second side wall  256 . Side walls  254  and  256  are substantially planar surfaces spaced apart and parallel to one another. The spacing between side walls  254  and  256  define a gap  258 . The ends of slot  252  include circumferentially extending slot portions  260  and  262 . The circumferentially extending slot portions are symmetrically positioned in communication with the longitudinally extending slot  252  to form “T” shaped slot ends. Another circumferentially extending slot portion  264  is formed at the longitudinal mid-point of slot  252 . 
     A column of rivet body material  266  longitudinally extends from flanged head  16  to the open end of rivet body  12  and is circumferentially positioned between two slots  252 . Each column  266  buckles under compressive load during the rivet setting process to define legs  268  similar to legs  86  previously defined. The circumferentially extending slot portions  260 ,  262  and  264  form reduced cross-sectional areas in each column  266 . The reduced cross-sectional areas plastically deform first. As such, the axial locations of the circumferentially extending slot portions define where the bend radii will be positioned. Specifically, column  266  forms legs  268  shown in  FIG. 26  by bending at the axial location of slot portion  260  to form a first portion  270  of leg  268 . Column  266  bends again at the axial location of slot portions  264  and  262  to define a portion  272  of leg  268 . Accordingly, one skilled in the art should appreciate that the distance that leg  268  radially extends and that the axial spacing between surface  274  on leg portion  272  and surface  20  of flanged head  16  may be configured to a specific design application by defining the length of slot  252  and the axial position of circumferentially extending portions  260 ,  262  and  264 . 
       FIGS. 27 and 28  depict another alternate embodiment blind rivet at reference numeral  300 . Blind rivet  300  is substantially similar to the rivet embodiment depicted in  FIGS. 14-16  except that the rivet body includes an additional set of intermediate indentations  302 . Intermediate indentations  302  assist in controlling the shape of the rivet body outer diameter. Specifically, intermediate indentations  302  define the barrel shape of a plurality of column portions  304 . Column portions  304  are circumferentially spaced apart from one another and positioned between indentations  102 . Intermediate indentations  302  function to encourage the column portions  304  to bend at their longitudinal mid-point. 
       FIG. 29  shows another alternate embodiment blind rivet  350 . Blind rivet  350  includes an elastomeric seal  352  positioned within a pocket  354  formed in flanged head  16 . Elastomeric seal  352  sealingly engages workpiece  76  and rivet body  12  to resist ingress of contamination to the joint. An aesthetically-pleasing cap  356  is coupled to flanged head  16 . Cap  356  engages flanged head  16  in a snap-fit arrangement where a lip  358  of cap  356  biasedly engages flanged head  16 . It can be appreciated in  FIG. 29  that the uniform diameter section  73  of mandrel  14  provides resistance to ingress of moisture when the rivet is set by having a tight or interference fit in the rivet body  26  at a location  357  adjacent to the flange  16 . Cap  356  may be colored to match or complement the environment in which it is placed. 
     Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.