Abstract:
An alignment pin or fastener includes a radially eccentric part such that when the fastener is tightened, the eccentric part shifts radially to simultaneously align the holes of two plates in a radial direction and clamp the two plates together in an axial direction. The bi-directional fastener includes two heads at opposite ends of a shaft, wherein the two plates become sandwiched and clamped between the two heads. The shaft and the two heads remain fixed relative to each other, so turning one head turns the other. This allows the fastener to be tightened even when only one of the heads is accessible.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The subject invention generally relates to expanding diameter alignment pins and fasteners and more specifically to an alignment pin or fastener that clamps both radially and axially. 
   2. Description of Related Art 
   In many manufacturing processes, such as machining and welding, fixtures are often used to accurately position and hold the work piece to a worktable. Worktables often have an array of holes that allow specially designed fasteners or alignment pins to quickly and accurately fasten the fixtures and/or the work piece to the table. Common examples of such fasteners or pins include collets, ball lock pins, and adjustable diameter bolts. Such devices can be used not only for attaching fixtures and work pieces to tables, but they may also be used for other applications as well. Although the devices may have broad application, they do have their drawbacks. 
   Collets, typically include a threaded rod that screws into a tapered piece, which forces the exterior of the collet to expand radially as the threaded rod is tightened. Collets typically clamp and align in just a radial direction without providing any significant axial clamping. In some cases, operation of a collet requires access to both ends of the collet, which is not always available. 
   Ball lock pins usually comprise a screw that threads into a hollow pin. As the screw turns into the pin, the screw forces one or more balls radially outward from inside the pin. When the pin is inserted into a hole of some part, the radially protruding balls press against the part to hold the pin in place. Depending on the design, such ball lock pins have limited ability to clamp and align. Also, such pins usually include several precise parts that can be expensive to make and difficult to maintain in good operating condition. Moreover, actuating ball lock pins usually require many turns of the screw before the balls fully engage. This can take time, which is limited in high production applications. Lastly, in order for a ball lock pin to accurate align two parts, the parts themselves need to be accurately machined, which can be expensive. 
   An adjustable diameter bolt, as disclosed in U.S. Pat. No. 5,284,408 and other patents by Duran; comprises a series of internally actuated collets. Such a bolt includes several relatively small parts that may jamb when exposed to dirty environments such as welding or machining. 
   Consequently, a need exists for a quick-actuating alignment pin that can clamp radially and axially, and do so with only having to access one end of the pin. 
   SUMMARY OF THE INVENTION 
   To overcome the problems and limitations of current fasteners and alignment pins, it is an object of some embodiments of the invention to provide a dual-clamping fastener that clamps in both a radial and axial direction. 
   Another object of some embodiments is to provide such a dual-clamping fastener with the ability to be actuated with access from only one end of the fastener. 
   Another object of some embodiments is to provide a dual-clamping fastener with a head at opposite ends, wherein the two heads are turned in unison by a single handle. 
   Another object of some embodiments is to provide dual-head, dual-clamping fastener, wherein a handle could be attached to either head. 
   Another object of some embodiments is to provide such a dual-clamping fastener with a minimal number of parts. 
   Another object of some embodiments is to provide a dual-clamping fastener with a radially expandable sleeve that includes a single slit to ensure maximum circumferential contact with the two bores in which the fastener is inserted. 
   Another object of some embodiments is to provide a dual-clamping fastener that provides a snap-into-position feel as the fastener is actuated. 
   Another object of some embodiments is to simultaneously align and clamp two parts together. 
   Another object of some embodiments is to use a duel-clamping fastener to simultaneously align and clamp two parts together without having to use an additional separate tool. 
   One or more of these and/or other objects of the invention are provided by a fastener that includes radially eccentric parts such that when the fastener is actuated, at least one of the eccentric parts shifts radially to simultaneously provide alignment and clamping in both a radial and axial direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a fastener according to one embodiment of the invention. 
       FIG. 2  is a front view of the fastener of  FIG. 1  showing the fastener being installed in one or more plates that shown in cross-section. 
       FIG. 3  is similar to  FIG. 2  but showing the fastener in place and in a release position. 
       FIG. 4  is similar to  FIG. 3  but showing the fastener in a lock position. 
       FIG. 5  is a cross-sectional view taken along an imaginary plane identified by line- 5 — 5  of  FIG. 3 . 
       FIG. 6  is a cross-sectional view taken along line  6 — 6  of  FIG. 3 . 
       FIG. 7  is a cross-sectional view taken along line  7 — 7  of  FIG. 4 . 
       FIG. 8  is a cross-sectional view taken along line  8 — 8  of  FIG. 4 . 
       FIG. 9  is a geometric figure that helps illustrate the axial clamping feature of a fastener according to some embodiments of the invention. 
       FIG. 10  is another geometric figure that helps illustrate the axial clamping feature of a fastener according to some embodiments of the invention. 
       FIG. 11  is similar to  FIG. 4  but showing another embodiment of a fastener in its lock position. 
       FIG. 12  is a cross-sectional view similar to  FIG. 5  but taken along line  13 — 13 ; however, the view is when the fastener of  FIG. 11  is in its release position as opposed to its actual illustrated lock position. 
       FIG. 13  is a cross-sectional view similar to  FIG. 7  but taken along line  13 — 13  when the fastener of  FIG. 11  is in its lock position. 
       FIG. 14  is an exploded perspective view of a fastener according to another embodiment of the invention. 
       FIG. 15  is a front view similar to  FIG. 2  but showing the fastener of  FIG. 14 . 
       FIG. 16  is a front view similar to  FIG. 3  but showing the fastener of  FIG. 14  in a release position. 
       FIG. 17  is a front view similar to  FIG. 4  but showing the fastener of  FIG. 14  in a lock position. 
       FIG. 18  is similar to  FIG. 4  but showing another embodiment of a fastener in its lock position. 
       FIG. 19  is a perspective view of another embodiment of a radially expandable sleeve. 
       FIG. 20  is similar to  FIG. 4  but showing another embodiment of a fastener in its lock position. 
       FIG. 21  is similar to  FIG. 3  but showing another embodiment of a fastener in its release position. 
       FIG. 22  is similar to  FIG. 4  but showing another embodiment of a fastener in its lock position. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An alignment pin or a fastener  10  for radially aligning and axially clamping is shown in  FIGS. 1–4 .  FIG. 1  shows an exploded perspective view of fastener  10 , and  FIGS. 2–4  show how fastener  10  can align and fasten an upper plate  12  to a lower plate  14 . 
   Fastener  10  comprises a radially expandable sleeve  16  that fits over a shaft  18 . Shaft  18  has a cam head  20  at one end and a clamp head  22  at an opposite end. For ease of use, a handle  24  may extend from clamp head  22  or cam head  20 . In some cases, shaft  18  connects to clamp head  22  by inserting a square end  26  of shaft  18  into a mating square hole  28  in clamp head  22  and screwing a nut  30  onto a threaded end  32  of shaft  18 . Of course, there are many other ways of connecting shaft  18 , clamp head  22 , and cam head  20  together so they move as a unit. Although various features of fastener  10  may vary, and the piece or pieces to which the fastener is attached may also vary, fastener  10  provides a good illustrative example of the invention&#39;s basic structure and function. 
   To operate fastener  10 , a hole  34  in upper plate  12  is first roughly aligned with a hole  36  in lower plate  14 , as shown in  FIG. 2 . Rotating sleeve  16  (see arrow  38 ) to be concentrically aligned with cam head  20  allows fastener  10  to be inserted (arrow  40 ) through holes  34  and  36 , as shown in  FIG. 3 . A slit  58  can be aligned with alignment mark  95  ( FIG. 1 ) in clamp head  22  or cam head  20  to help coaxially align sleeve  16  with cam head  20 . Mark  95  can be a groove, a raised ridge, a flat line, or any mechanical or visual feature that helps align sleeve  16  with the rest of fastener  10 . When properly aligned, an oblong hole  42  in sleeve  16  allows shaft  18  to be biased off to one side of sleeve  16 , so a longitudinal centerline  44  of shaft  18  is radially offset to a longitudinal centerline  46  of sleeve  16 , as shown in  FIG. 5 .  FIG. 6  shows a longitudinal centerline of cam head  48  being radially offset to the shaft&#39;s centerline  44 . As a result, when fastener  10  is in the position of  FIG. 3 , the sleeve&#39;s longitudinal centerline  46  and the cam head&#39;s longitudinal centerline  48  are coaxially aligned with holes  34  and  36 , and the shaft&#39;s longitudinal centerline  44  is radially offset to the holes. 
   Next, to more accurately align holes  34  and  36 , and to simultaneously and axially clamp pieces  12  and  14  together, handle  24  can be used to rotate clamp head  22 , as indicated by arrow  50  of  FIG. 4 . The rotation can be a quick and short turn of 180-degrees or less. Since shaft  18  holds cam head  20  and clamp head  22  in a substantially fixed relationship with each other, shaft  18  and the two heads  20  and  22  rotate as one. Meanwhile, friction between sleeve  16  and the inner diameters of holes  34  and  36  resists the rotation of sleeve  16  within the holes as handle  24  rotates shaft  18  and heads  20  and  22 . Rotating handle  24  forces cam head  20  radially against a lower edge  52  of piece  14 . In reaction to that, shaft  18  moves from a release position of  FIG. 5  to a clamp position of  FIG. 7 . More specifically, rotating handle  24  forces shaft  18  to move from a wider end  54  of opening  42  to a narrower end  56 , where a full-length slit  58  exists in sleeve  16 . The diameter of shaft  18  is wider than narrower end  56 , so slit  58  enables shaft  18  to expand sleeve  16  radially, as indicated by arrows  60 . The radial expansion of sleeve  16  is what accurately aligns holes  34  and  36 . When shaft  18  is pressed into the narrower end  56  of opening  42 , friction between shaft  18  and cylinder  16  helps hold fastener  10  in its clamped position. 
   In addition to the radial expansion of sleeve  16 , an inclined cam surface  62  of cam head  20  pressing against lower edge  52  urges edge  52  to slide up along cam surface  62 . This urges edge  52  to move closer to an axial clamping surface  64  of clamp head  22 , whereby pieces  12  and  14  are axially clamped between cam surface  62  and axial clamping surface  64 . 
   To express this axial clamping feature geometrically, the unstressed outer diameter of sleeve  16  defines or lies along an imaginary cylinder  66 , as shown in  FIGS. 9 and 10 . Cylinder  66  comprises an infinite number of parallel lines  68  of which at least some define a plurality of line segments  70  that terminate at axial clamping surface  64  and cam surface  62 . The plurality of line segments  70  include a shortest line segment  72  having a length  74  that varies upon rotating sleeve  16  or cylinder  66  relative to cam head  20  and clamp head  22 . The shortening of length  74  is what creates the axial clamping aspect of fastener  10 . 
   Although lower edge  52  of piece  14  is chamfered to broaden the contact area between cam surface  62  and edge  52 , the lower edge of hole  36  does not necessarily have to be chamfered. The beveled surface  62  of cam head  20  can simply engage the sharp corner of a hole whose edge is not chamfered. This, however, would create an area of high stress concentration at the point where cam surface  62  meets the sharp edge. High stress concentrations can be avoided by providing a fastener  10 ′ with a cam head  20 ′ that has a modified cam surface  62 ′, as shown in  FIG. 11 . 
   Cam surface  62 ′ comprises a helical ramp  76  and a radial cam surface  78 . Upon turning handle  24  of fastener  10 ′, radial cam surface  78  pushes radially against the inside diameter of hole  36 ′, which forces a shaft  18 ′ to move form its release position of FIG.  12  to its clamp position of  FIG. 13 . Similar to sleeve  16 , a sleeve  16 ′ expands radially as shaft  18 ′ moves from a wider end  54 ′ of oblong hole  42 ′ to a narrower end  56 ′. 
   In this example, sleeve  16 ′ includes a neck  80  through which shaft  18 ′ must pass to move between wider end  54 ′ and narrower end  56 ′. Neck  80  provides a snap-into-position feel as fastener  10 ′ is actuated between the release the lock positions. With neck  80 , sleeve  16 ′ and/or shaft  18 ′ should be sufficiently flexible to enable shaft  18 ′ to pass through neck  80  because the width of neck  80  is narrower than the outside diameter of shaft  18 ′ and the widths of ends  54 ′ and  56 ′. The flexibility can be achieved with proper material selection and/or by making shaft  18 ′ hollow, whereby shaft  18 ′ or sleeve  16 ′ can deflect as shaft  18 ′ passes through neck  80 . 
   Another way of eliminating the need for chamfering the hole in a lower piece to be aligned and clamped is by inverting fastener  10 . With some additional minor changes, inverting fastener  10  creates a modified fastener  10 ″ as shown in  FIGS. 14–17 , which correspond to  FIGS. 1–4  respectively. Fastener  10 ″ is installed in a manner similar to that of fastener  10 ; however, clamp head  22 ″ is lowered first into holes  34 ″ and  36 ″ of upper plate  12 ″ and lower plate  14 ″ respectively. A hex head  82 , handle, or other gripping means is attached to a cam head  20 ″ that has a cam surface  62 ″. Once fastener  10 ″ is in the release position of  FIG. 16 , hex head  82  allows cam head  20 ″ to be readily turned, just as handle  24  turns clamp head  22 . 
   Rotating hex head  82  forces cam head  20 ″ radially against an upper edge  84  of piece  12 ″. In reaction to that, shaft  18 ″ moves from a release position of  FIG. 16  to a clamp position of  FIG. 17 . More specifically, rotating cam head  82 , shaft  18 ″ and clamp head  22 ″ forces shaft  18 ″ to move from wider end  54  of opening  42  to narrower end  56 . The diameter of shaft  18 ″ is wider than narrower end  56 , so slit  58  enables shaft  18 ″ to expand sleeve  16  radially, as is the case with fastener  10 . Again, the radial expansion of sleeve  16  is what accurately aligns holes  34 ″ and  36 ″. When shaft  18 ″ is pressed into the narrower end  56  of opening  42 , friction between shaft  18 ″ and sleeve  16  helps hold fastener  10 ″ in its clamped position. 
   In addition to the radial expansion of sleeve  16 , the inclined cam surface  62 ″ of cam head  20 ″ pressing against upper edge  84  urges edge  84  to slide up along cam surface  62 ″. This urges edge  84  to move closer to an axial clamping surface  64 ″ of clamp head  22 ″, whereby pieces  12 ″ and  14 ″ are axially clamped between cam surface  62 ″ and axial clamping surface  64 ″. 
   Other variations of the invention are shown in  FIGS. 18–22 . In these drawing figures and others, the three-digit numerals that identify various elements correspond to the two-digit numerals of the  FIGS. 1–17 , wherein  110  and  210  corresponds to  10 ,  112  corresponds to  12 ,  114  corresponds to  14 , etc. Corresponding elements (e.g., handle  24  and  124 ) are elements that are quite similar in structure and function, but are not necessarily identical. 
   A fastener  110  ( FIG. 18 ) can be provided with a plurality of irregularities  90  that engage a mating plurality of irregularities  92  in plate  114 . The mating engagement of irregularities  90  and  92  helps hold fastener  110  in its clamped position. The structure of the irregularities can assume many shapes such as the protuberances and mating dimples of  FIG. 18  or the mating serrations  190  and  192  of  FIG. 20 . The saw tooth serrations  190  and  192  may provide more permanent clamping than irregularities  90  and  92 . 
   To accommodate slightly different hole diameters of plates  112  and  114 , a sleeve  116  can be provided with a slit  92  that lies generally perpendicular to the sleeve&#39;s longitudinal centerline. Slit  92  lies between two axially offset portions  93  and  94  of sleeve  116 . With slight bending of shaft  118 , slit  92  allows portions  93  and  94  to expand independently of each other, so portion  93  can grip the inside hole diameter of plate  112 , and portion  94  can grip the inside hole diameter of plate  114 . 
   Another fastener  210  is illustrated in  FIGS. 21 and 22 , which correspond to  FIGS. 3 and 4  respectively. Fastener  210  is similar to fastener  10  except sleeve  116  replaces sleeve  16 , and fastener  210  includes a lock pin  91  that is axially movable relative to at least one of clamp head  122  and cam head  20 . Lock pin  91  is movable between an unlock position of  FIG. 21  and a lock position of  FIG. 22 . When in the lock position, pin  91  engages a hole in plate  112  to prevent handle  124  from moving relative to plate  112 . Pin  91  can be a separate pin as shown, or pin  91  can be attached to handle  124  with just a nose portion of pin  91  being movable in and out of the hole in plate  112 . Pin  91  represents any axially moving element that helps hold handle  124  fixed relative to plate  112 . Examples of pin  91  include, but are not limited to, a screw, a smooth round pin, a spring-loaded pin, a spring-loaded ball plunger, etc. 
   Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those skilled in the art. Various features of the disclosed embodiments can be interchanged or used in combination with each other. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.