Patent Publication Number: US-9903403-B2

Title: Fastener and method of installing same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/791,088, filed Mar. 8, 2013, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/620,296, filed on Apr. 4, 2012, and entitled “Fastener and Method of Installing Same.” The disclosures set forth in the referenced applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to fasteners for assembly of two or more panels of a workpiece, and more particular to a blind fastener that forms an enlarged blind head spaced from the workpiece surface against which it comes to bear. 
     2. Description of the Background 
     Laminated composite materials are prone to crushing and delamination when subjected to extreme compressive stresses, as can occur when fastening. To avoid crushing with conventional fasteners washers and fastener components with enlarged bearing surfaces are employed. The manufactured head of blind fasteners can also be equipped with an enlarged bearing surface but the blind heads of existing blind fasteners do not develop an enlarged blind side bearing surface until after contact with the workpiece surface. Initial contact of a bulbing sleeve with laminated composite materials can, and does, cause localized crushing which can weaken the workpiece. 
     A need therefore exists for a blind fastener for laminated composites and other fragile construction materials that forms an enlarged blind side bearing surface prior to contacting the workpiece surface. 
     SUMMARY 
     According to one aspect of the present disclosure, a fastener includes a body having a deformable first end, a second end, and a passage extending through the body between the first and second ends. The fastener further includes a corebolt having first and second ends and a region of reduced diameter disposed between the first and second ends and a sleeve having first and second ends, the second end having a bulbing portion. The corebolt is disposed within the sleeve and the body with the first end of the corebolt in engagement with the first end of the sleeve and the first end of the body disposed adjacent the second end of the sleeve. The bulbing portion is adapted to form an enlarged blind head when the corebolt is rotated in relation to the sleeve and the first end of the body is adapted to deform inwardly into the region of reduced diameter to allow movement of the blind head along the body. 
     According to another aspect of the present disclosure, a fastener includes a body having a deformable first end, a second end, and a threaded passage extending at least partially through the body between the first and second ends. The fastener further includes a corebolt having first and second ends, the first end having an enlarged head, and a region of reduced diameter between the first and second ends, and a sleeve having first and second ends, the second end having a bulbing portion. The corebolt is disposed within the sleeve and the body with the corebolt in threaded engagement with the body and the first end of the body disposed adjacent the second end of the sleeve. The bulbing portion is adapted to form an enlarged blind head when the corebolt is rotated in relation to the body and the first end of the body is adapted to deform inwardly into the region of reduced diameter to allow movement of the blind head along the body. 
     According to yet a further aspect of the present disclosure, a fastener includes a body having deformable first end, a second end, and a passage extending through the body between the first and second ends. The fastener further includes a corebolt having first and second ends and a region of reduced diameter disposed between the first and second ends, a first sleeve having first and second ends, the second end having a bulbing portion, and a second sleeve having first and second ends. The corebolt is disposed within the first sleeve, the second sleeve, and the body with the first end of the corebolt in engagement with the first end of the second sleeve, the second end of the second sleeve disposed adjacent the first end of the first sleeve, and the first end of the body disposed adjacent the second end of the first sleeve. The bulbing portion is adapted to form an enlarged blind head when the corebolt is rotated in relation to the sleeve. The first end of the body is adapted to deform radially inwardly into the region of reduced diameter to allow movement of the blind head along the body. 
     According to another aspect of the present disclosure, a method of installing a fastener within a workpiece includes the step of providing a fastener having a sleeve disposed adjacent a first end of a corebolt and a body disposed over the corebolt and having a deformable end disposed adjacent an end of the sleeve. The method further includes the steps of placing the fastener into aligned apertures in a workpiece and rotating the corebolt while restraining the body. The method further includes the steps of causing a weakened portion formed in an end of the sleeve to bulb outwardly and deforming the deformable end of the body into a region of reduced diameter in the corebolt. The method still further includes the step of bringing a blind head against a workpiece. 
     Other aspects and advantages of the present disclosure will become apparent upon consideration of the following drawings and detailed description, wherein similar structures have similar reference numbers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the accompanying figures in which like reference numerals indicate like features and wherein: 
         FIG. 1  shows a top isometric view of a first embodiment of a fastener; 
         FIG. 2  is a side elevational view of the fastener of  FIG. 1 ; 
         FIG. 3  is a side elevational view of a corebolt of the fastener of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view taken generally along the lines  4 - 4  of  FIG. 1  and depicting a cylindrical sleeve of the fastener; 
         FIG. 5  is a side elevational view of a body of the fastener of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view taken generally along the lines  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a cross-sectional view taken generally along the lines  7 - 7  of  FIG. 2 ; 
         FIG. 8  is a side elevational view of the fastener of  FIG. 1  installed within a workpiece; 
         FIG. 9  is a cross-sectional view taken generally along the lines  9 - 9  of  FIG. 8 ; 
         FIGS. 10-14  depict various stages of a sequence of forming a blind head as predicted by computer simulation; 
         FIG. 15  is a side elevational view of a second embodiment of a fastener; 
         FIG. 16  is a cross-sectional view taken generally along the lines  16 - 16  of  FIG. 15 ; 
         FIG. 17  is a cross-sectional view showing the fastener of  FIG. 15  during a phase of installation in minimum grip in which the blind head has been formed but not yet moved into contact with the workpiece; 
         FIG. 18  is a cross-sectional view similar to  FIG. 17  and showing the fastener of  FIG. 15  in a minimum grip condition upon completion of installation; 
         FIG. 19  is a cross-sectional view similar to  FIG. 17  and showing the fastener of  FIG. 15  in a maximum grip condition upon completion of installation; 
         FIG. 20  is a side elevational view of a third embodiment of a fastener; 
         FIG. 21  is a cross-sectional view taken generally along the lines  21 - 21  of  FIG. 20 ; 
         FIG. 22  shows a top isometric view of a fourth embodiment of a fastener; 
         FIG. 23  is a side elevational view of the fastener of  FIG. 22 ; 
         FIG. 24  is a cross-sectional view taken generally along the lines  24 - 24  of  FIG. 23 ; 
         FIG. 25  is an exploded perspective assembly view of the fastener of  FIG. 22 ; 
         FIG. 26  shows a side elevation view of a fifth embodiment of a fastener; 
         FIG. 27  is a cross-sectional view taken generally along the lines  27 - 27  of  FIG. 26 ; and 
         FIG. 28  is an exploded perspective assembly view of the fastener of  FIG. 26 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-7 , a first embodiment of a fastener or blind bolt  10  in accordance with the present disclosure includes a generally cylindrical body  20 . As best seen in  FIGS. 5 and 6 , the body  20  includes a passage  22  disposed through a central portion of the body  20 . An inner surface  24  of a wall  26  forming the passage  22  is generally smooth. A tapered ramp  30  is disposed at a first end  32  of the body  20  and an enlarged head  34  having a wrenching portion  35  is disposed at a second end  36  of the body  20 . A radial groove  38  separates the wrenching portion  35  and the enlarged head  34 . 
     A generally cylindrical corebolt  50 , as best seen in  FIG. 3 , is concentrically disposed within the passage  22  of the body  20 . The corebolt  50  includes a threaded portion  52  at a first end  54  of the corebolt  50 , a cylindrical shank  56  formed in the center of the corebolt  50 , and a frangible wrenching portion  58  disposed at a second end  60  of the corebolt  50 . An enlarged head  62  is positioned between the cylindrical shank  56  and the wrenching portion  58 , the enlarged head  62  having a diameter greater than a diameter of the cylindrical shank  56 . A region of reduced diameter in the form of a radial groove  64  having a diameter smaller than a diameter of the enlarged head  62 , the wrenching portion  58 , and the cylindrical shank  56  is located between the threaded portion  52  and the cylindrical shank  56 , the function of which will be discussed in greater detail hereinafter. 
     As seen in  FIGS. 2 and 4 , a deformable cylindrical sleeve  70  abuts the first end  32  of body  20 . The cylindrical sleeve  70  has a first end  72  that is threaded and a second end  74  that is not threaded. The second, non-threaded end  74  may include regions of varying wall thickness, such as tapers, grooves, and the like, to cause a region  80  near the second end  74  to bulb, forming an enlarged blind head, as will be discussed in detail below. As seen in  FIG. 4 , the region  80  includes tapered walls  82 ,  84  that create a weakened portion  86 . While the weakened portion  86  is shown as a thinned area, the weakened portion  86  may be weakened in any fashion that would allow for bulbing of the sleeve at region  80 , for example, a radial groove, one or more indentations, a thinner, flexible material, localized annealing or heat treatment, and the like. 
     The cylindrical sleeve  70  preferably has a diameter that creates a clearance fit with an aperture  100  in a workpiece  102  ( FIGS. 8 and 9 ) so as to avoid damage to blind side plies  104  of laminated composite workpiece  102  during insertion of the fastener  10  into the workpiece. Similarly, the body  20  may create a clearance fit or a slight interference fit with the aperture  100  in the workpiece  102 , depending on the specific application and workpiece materials. 
     Referring to  FIGS. 1, 2, and 7 , when assembled, the threaded first end  72  of the cylindrical sleeve  70  is disposed over the first end  54  of the corebolt  50  such that the first end  72  is in threaded engagement with the threaded portion  52  of the corebolt  50 . The body  20  is also disposed over at least a central portion of the corebolt  50  with the enlarged head  62  of the corebolt  50  disposed within the enlarged head  34  of the body  20 , preventing inward movement of the corebolt  50  within the body  20 . A second end  74  of the cylindrical sleeve  70  is also compressed tightly against the first end  32  of body  20  so as to rotationally restrain the cylindrical sleeve  70  during the initial stages of installation. Knurls, friction enhancing coatings, or interlocking surfaces may be used to produce this rotational restraint. 
       FIGS. 8 and 9  depict the fastener  10  of  FIGS. 1, 2, and 7  as the fastener  10  is installed within the workpiece  102 . The fastener  10  may be installed using any installation tool known in the art. The workpiece  102  is comprised of two or more sheets, or panels, of material, or two or more structural elements. Before installation of the fastener  10  into the workpiece  102 , the fastener is inserted into aligned apertures  100  of the elements of the workpiece  102  until the enlarged head  34  of the body  20  is seated against the workpiece  102 . An installation tool is then used, which engages the wrenching portion  35  of the body  20  and the wrenching portion  58  of the corebolt  50 . In doing so, the body  20  is rotationally restrained as the corebolt  50  is rotated. Rotation of the corebolt  50  causes the corebolt  50  to thread into the cylindrical sleeve  70 , thereby compressing the region  80  of the cylindrical sleeve  70  against the first end  32  of the body  20  (see  FIG. 10 ). In particular, the tapered walls  82 ,  84  move outwardly and toward one another at weakened portion  86 . This compression causes the region  80  of the cylindrical sleeve  70  to bulb outwardly (see  FIG. 11 ), forming an enlarged blind head  110 . After the region  80  has bulbed, the second end of the cylindrical sleeve  70  moves onto the tapered ramp  30  of the body  20  (see  FIG. 12 ), causing the tapered ramp  30  to deform inwardly into the radial groove  64  of the corebolt  50 . This deformation of the tapered ramp  30  removes the obstruction formed by the first end  32  of the body  20  that previously restricted axial movement of the cylindrical sleeve  70  so that the cylindrical sleeve  70  can now travel along the tapered ramp  30  (see  FIG. 13 ) and an outer surface  120  of the body  20  until the enlarged blind head  110  comes to bear against the workpiece  102  (see  FIGS. 9 and 14 ). 
     As enlarged blind head  110  compresses against workpiece surface  102 , the torque required to continue rotating corebolt  50  increases until the wrenching portion  58  of the corebolt  50  separates at the enlarged head  62  as suggested in  FIG. 9 , terminating the installation phase. For example, as shown in  FIG. 21 , the corebolt  50  is formed to include a radial groove  65  between the wrenching portion  58  and the enlarged head  62  to facilitate separation of the wrenching portion  58 . The wrenching portion  35  of the body  20  is then twisted off and broken at the radial groove  38  to produce a recess-free and substantially flush surface against the enlarged head  34  of the body  20 . Optionally, the enlarged head  34  of the body  20  may be provided with recesses, as are known in the art to rotationally restrain the body  20  during installation. 
     While the first end  32  of the body  20  is shown as having a tapered ramp  30  and the corebolt  50  is shown as having a radial groove  64  in the embodiment of  FIGS. 1-7 , any other feature or features that allow for deformation of the first end of the body  20  may be utilized in place of the tapered ramp  30  and/or radial groove  64 . For example, the radial groove  64  may be replaced by an area of reduced diameter, as will be discussed in greater detail hereinafter. 
     An alternative embodiment of a fastener  200  is illustrated in  FIGS. 15 and 16 . The fastener  200  includes a generally cylindrical body  220  having a passage  222  disposed through a central portion of the body  220 . A central portion  223  of a wall  224  forming the passage  222  is threaded. A tapered ramp  230  is disposed at the first end  226  of the body  20  and an enlarged head  234  having a wrenching portion  235  is disposed at the second end  228  of the body  20 . 
     A generally cylindrical corebolt  250  is concentrically disposed within the passage  222  of the body  220 . The corebolt  250  includes a first end  252  having an enlarged retaining member  254 , a central threaded portion  256  that engages the central threaded portion  223  of the body  220 , and a second end  260  that extends out of the body  220  and includes wrenching means  262 . The wrenching means  262  may be a separate piece attached by press fit, with adhesives, or by staking to the second end  260  of the corebolt  250  or may be integral with the corebolt  250 . The corebolt  250  also includes a region of reduced diameter in the form of an unthreaded region  263  that allows for deformation of the tapered ramp  230 , as will be discussed in greater detail below. The unthreaded region  263  has a diameter less than a major diameter of the threaded portion  223 . A radial notch or groove  264  is also disposed in the threaded portion  256  of the corebolt  250 , as will be discussed in greater detail below. 
     Still referring to  FIGS. 15 and 16 , a deformable cylindrical sleeve  270  abuts the first end  226  of body  220 . The cylindrical sleeve  270  has a first end  272  that rests against a ledge  273  formed by the enlarged head  254  of the corebolt  250  and a second end  274  that may include regions of varying wall thickness, such as tapers, grooves, and the like, to cause a region  280  near the second end  274  to bulb, forming an enlarged blind head, as will be discussed in detail below. The region  280  is similar to the region  80  shown in  FIG. 4 . 
     The cylindrical sleeve  270  preferably has a diameter that creates a clearance fit with an aperture  100  in a workpiece  102  (see  FIGS. 17-19 ) so as to avoid damage to blind side plies  104  of a laminated composite workpiece  102  during insertion of the fastener  200  into the workpiece  102 . Similarly, a diameter of the cylindrical body  220  may create a clearance fit or a slight interference fit with the aperture  100  in the workpiece  102 , depending on the specific application and workpiece materials. 
     When the fastener  200  is assembled, the central threaded portion  223  of the body  220  threadedly engages the central threaded portion  256  of the corebolt  250  and the cylindrical sleeve  270  is disposed between the first end  226  of the body  220  and the enlarged head  254  of the corebolt  250 . 
       FIG. 17  depicts the fastener  200  as it is being installed within the workpiece  102  and  FIGS. 18 and 19  depict the fastener  200  in minimum and maximum grip conditions, respectively. During installation, as the corebolt  250  is threaded into the body  220 , the retaining member  254  of the corebolt  250  pushes the cylindrical sleeve  270  toward the body  220 , compressing the cylindrical sleeve  270  against the first end  226  of the body  220 , causing the cylindrical sleeve  270  to bulb at region  280 , as seen in  FIGS. 18 and 19 . As threading of the corebolt  250  into the body  220  continues, the tapered ramp  230  of the body  220  deforms inwardly into the unthreaded region  263  of the corebolt  250  due to pressure exerted by the cylindrical sleeve  270  on the body  220 , allowing the cylindrical sleeve  270  to advance toward the workpiece  102 , forming a blind head  300 . Upon clamping of the workpiece  102  by the cylindrical sleeve  270 , an increase in applied torque causes the wrenching means  262  of the corebolt  250  to sever from the rest of the corebolt  250  at the groove  264 . The optional wrenching means  235  on the enlarged head  234  may then be removed from the body  220  by twisting. Depending on the thickness of the workpiece  102 , the fastener  220  may be installed in a minimum grip condition, as seen in  FIG. 18 , or a maximum grip condition, as seen in  FIG. 19 . 
     A variation of the fastener  10  of  FIGS. 1-7  is depicted in  FIGS. 20 and 21 . The fastener  10  of  FIGS. 20 and 21  is similar to the fastener  10  of  FIGS. 1-7  and, thus, similar reference numbers will be utilized and only the differences will be described. In particular, the fastener  10  of  FIGS. 20 and 21  includes a shortened sleeve  70  with features similar to that described in relation to the sleeve  70  of  FIGS. 1-7 , except that the passage  71  is unthreaded. A second sleeve  301  is disposed adjacent the first end  72  of the sleeve  70  and includes an inner threaded passage  302  in threaded engagement with the first end  54  of the corebolt  50 . The fastener  10  having two sleeves  70 ,  301  functions in the same manner as described with respect to  FIGS. 8-14 . 
     Referring to  FIGS. 22-25 , another embodiment of a fastener or blind bolt  410  in accordance with the present disclosure includes a generally cylindrical body  420  and a generally cylindrical corebolt  450  concentrically disposed within a passage  422  of the body  420 . As best seen in  FIG. 24 , the body  420  includes the passage  422  disposed through a central portion of the body  420 . An inner surface  424  of a wall  426  forming the passage  422  is generally smooth. A tapered ramp  430  is disposed at a first end  432  of the body  420  and an enlarged head  434  having a wrenching portion  435  is disposed at a second end  436  of the body  420 . A radial groove  438  separates the wrenching portion  435  and the enlarged head  434 . Tapered ramp  430  is separate from body  420  as shown in  FIG. 25 . The separate tapered ramp  430  disposed at the first end  432  of the body  420  may be formed from the same or a different material as the body  420 . The tapered ramp  430  may be formed by machining, forging, stamping, or wrapping a shaped wire around a mandrel with or without the ends secured together, for example. 
     The corebolt  450 , as best seen in  FIGS. 24 and 25 , includes a threaded portion  452  at a first end  454  of the corebolt  450 , a cylindrical shank  456  formed in the center of the corebolt  450 , and a frangible wrenching portion  458  disposed at a second end  460  of the corebolt  450 . An enlarged head  462  is positioned between the cylindrical shank  456  and the wrenching portion  458 , the enlarged head  462  having a diameter greater than a diameter of the cylindrical shank  456 . The corebolt  450  is formed to include a radial groove  465  between the wrenching portion  458  and the enlarged head  462  to facilitate separation of the wrenching portion  458 . A region of reduced diameter in the form of a radial groove  464  having a diameter smaller than a diameter of the enlarged head  462 , the wrenching portion  458 , and the cylindrical shank  56  is located between the threaded portion  452  and the cylindrical shank  456 , the function of which will be discussed in greater detail hereinafter. 
     As seen in  FIG. 24 , a deformable cylindrical sleeve  470  abuts the tapered ramp  430  disposed at the first end  432  of body  420 . A frictional interface, such as knurls or a press fit, may be used to rotationally restrain tapered ramp  430  with body  420 . The cylindrical sleeve  470  has a first end  472  that is threaded and a second end  474  that is not threaded. The second, non-threaded end  474  may include regions of varying wall thickness, such as tapers, grooves, and the like, to cause a region  480  near the second end  474  to bulb, forming an enlarged blind head, similar to sleeve  70  shown in  FIGS. 1-14 . 
     Referring to  FIGS. 24 and 25 , when assembled, the threaded first end  472  of the cylindrical sleeve  470  is disposed over the first end  454  of the corebolt  450  such that the first end  472  is in threaded engagement with the threaded portion  452  of the corebolt  450 . The body  420  is also disposed over at least a central portion of the corebolt  450  with the enlarged head  462  of the corebolt  450  disposed within the enlarged head  434  of the body  420 , preventing inward movement of the corebolt  450  within the body  420 . A second end  474  of the cylindrical sleeve  470  is also compressed tightly against the tapered ramp  430  disposed at the first end  432  of body  420  so as to rotationally restrain the cylindrical sleeve  470  during the initial stages of installation. Knurls, friction enhancing coatings, or interlocking surfaces may be used to produce this rotational restraint. A lip  440  may be disposed at the second end  474  of the sleeve  470 . The lip  440  surrounds an end portion of the tapered ramp  430  to maintain the sleeve  470  in concentric alignment with the tapered ramp  430  during the bulbing phase of installation. 
     The fastener  410  is configured to be installed through a workpiece, such as the workpiece  102  shown in  FIGS. 8 and 9 . The fastener  410  may be installed using any installation tool known in the art. After insertion, an installation tool is then used, and the fastener  410  forms a blind head to engage the workpiece  102  similar to the fastener  10  shown in  FIGS. 1-14 . As enlarged blind head formed by the fastener  410  compresses against the workpiece surface, the torque required to continue rotating corebolt  450  increases until the wrenching portion  458  of the corebolt  450  separates at the enlarged head  462 , terminating the installation phase. The wrenching portion  435  of the body  420  is then twisted off and broken at the radial groove  438  to produce a recess-free and substantially flush surface against the enlarged head  434  of the body  420 . Optionally, the enlarged head  434  of the body  420  may be provided with recesses, as are known in the art to rotationally restrain the body  420  during installation. 
     An alternative embodiment of a fastener  500  is illustrated in  FIGS. 26-28 . The fastener  500  includes a generally cylindrical body  520  having a passage  522  disposed through a central portion of the body  520 . A central portion  523  of a wall  524  forming the passage  522  is threaded. A tapered ramp  530  is disposed at the first end  526  of the body  520  and an enlarged head  534  having a wrenching portion  535  is disposed at the second end  528  of the body  520 . A frictional interface, such as knurls or a press fit, may be used to rotationally restrain tapered ramp  530  with body  520 . Tapered ramp  530  is separate from body  520  as shown in  FIG. 28 . The separate tapered ramp  530  disposed at the first end  526  of the body  520  may be formed from the same or a different material as the body  520 . The tapered ramp  530  may be formed by machining, forging, stamping, or wrapping a shaped wire around a mandrel with or without the ends secured together, for example. 
     A generally cylindrical corebolt  550  is concentrically disposed within the passage  522  of the body  520 . The corebolt  550  includes a first end  552  having an enlarged head  554 , a central threaded portion  556  that engages the central threaded portion  523  of the body  520 , and a second end  560  that extends out of the body  520  and includes wrenching means  562 . The wrenching means  562  may be a separate piece attached by press fit, with adhesives, or by staking to the second end  560  of the corebolt  550  or may be integral with the corebolt  550 . The corebolt  550  also includes a region of reduced diameter in the form of an unthreaded region  563  that allows for deformation of the tapered ramp  530 , as will be discussed in greater detail below. The unthreaded region  563  has a diameter less than a major diameter of the threaded portion  523 . A radial notch or groove  564  is also disposed in the threaded portion  556  of the corebolt  550 , as will be discussed in greater detail below. 
     Still referring to  FIGS. 26-28 , a deformable cylindrical sleeve  570  abuts an end of tapered ramp  530 . The cylindrical sleeve  570  has a first end  572  that rests against a ledge  573  formed by the enlarged head  554  of the corebolt  550  and a second end  574  that may include regions of varying wall thickness, such as tapers, grooves, and the like, to cause a region  580  near the second end  574  to bulb, forming an enlarged blind head, as will be discussed in detail below. The region  580  is similar to the region  280  shown in  FIG. 16 . A lip  540  may be disposed at the second end  574  of the sleeve  570 . The lip  540  surrounds an end portion of the tapered ramp  530  to maintain the sleeve  570  in concentric alignment with the tapered ramp  530  during the bulbing phase of installation. 
     The cylindrical sleeve  570  preferably has a diameter that creates a clearance fit with an aperture  100  in a workpiece  102  (see  FIGS. 17-19 ) so as to avoid damage to blind side plies  104  of a laminated composite workpiece  102  during insertion of the fastener  500  into the workpiece  102 . Similarly, a diameter of the cylindrical body  520  may create a clearance fit or a slight interference fit with the aperture  100  in the workpiece  102 , depending on the specific application and workpiece materials. The fastener  500  is installed similar to fastener  200  shown in  FIGS. 15-19  and described above. 
     When the fastener  500  is assembled, the central threaded portion  523  of the body  520  threadedly engages the central threaded portion  556  of the corebolt  550  and the cylindrical sleeve  570  is disposed between ramp  530  and the enlarged head  554  of the corebolt  550 . 
     Any of the embodiments described herein may be modified to include any of the structures or methodologies disclosed in connection with other embodiments. 
     Further, although directional terminology, such as front, back, upper, lower, etc. may be used throughout the present specification, it should be understood that such terms are not limiting and are only utilized herein to convey the orientation of different elements with respect to one another. 
     Numerous modifications to the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.