Abstract:
A clamp for securing a tool to a multi-piece panel assembly. The clamp is especially suited for applications where access to only one side of the panel assembly is available. The clamp uses a blind temporary fastener that is secured to the panel assembly to hold the independent panels of the assembly together. The clamp includes an sleeve member that is attached to the temporary fastener and a socket that attaches to the sleeve member and is axially adjustable therewith. The clamp attaches to the temporary fastener without modification of the temporary fastener and clamps the tool to the panel assembly. The clamp is adjustable for a variety of tool thicknesses and can be removed without removal of the temporary fastener.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a clamp used to align and secure a tool to at least one part. 
     BACKGROUND OF THE INVENTION 
     In many environments it is necessary to temporarily secure a tool, such as a jig drill template or locating jig, to one or more parts while other operations, such as drilling and/or riveting operations, are performed. For example, temporary fasteners are often used in the aircraft industry to temporarily attach jig drill templates to a multi-layer structure in order to perform a drilling operation on the multi-layer structure. 
     Typically, clamps or fasteners are used to align the tool to the part(s) of a multi-layer structure and to apply a clamp load to the tool and the part(s) that clamps the tool and the part(s) together. These parts can include panels and structural members. Thereafter, an operation such as drilling a plurality of holes in the part(s) or riveting the part(s) together may be performed. 
     Known clamps frequently require access to both sides of the part(s), which may not be practical, convenient or comfortable for the technician, as for example when the parts are components of an aircraft and located in the wings or empennage. 
     Thus, what is needed is a temporary tool fastener that can be attached with access to only one side of a work surface and does not require modification of the temporary fastener. Such a tool would be especially useful in the fabrication and/or assembly of aircraft components, where access is often limited to only one side of a panel. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a temporary clamp that is useful for temporarily attaching a drill jig to an aircraft panel assembly. As will be described, the clamp utilizes an existing temporary fastener that positions the multiple layers of the panel assembly in preparation for fastening. Briefly, a drill jig or other tool can be attached to the panel assembly with the clamp. Holes are then formed in the panel assembly using the drill jig as a template. Rivets or other fasteners are inserted in the panel assembly holes before the temporary fasteners are removed. In one preferred form, the clamp comprises an elongated annular nut with external and internal threads. The internal threads attach to a draw bar of a temporary fastener and the external threads attach to a clamp socket. The clamp socket is an elongated annular portion with internal threads that are sized to mate with the external nut threads. When assembled, the clamp socket can be rotated relative to the nut to axially translate the clamp socket. This axial movement is used to impart a clamping force on a tool to secure the tool to the panel assembly that is attached to the temporary fastener. In another preferred form, the clamp attaches to the temporary fastener to allow for clearance for a thicker drill jig. In yet another preferred form, the clamp can be installed after the temporary fastener is installed on a work piece. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     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 a partially broken away perspective view illustrating a clamp constructed in accordance with the teachings of the present invention, the clamp being shown locating and clamping an exemplary tool to an exemplary part; 
     FIG. 2 is an enlarged view of a portion of FIG. 1 illustrating the clamp of the present invention and the tool in greater detail; 
     FIG. 3 is a sectional front view similar to that of FIG. 4; but illustrating only the temporary fastener as it is being inserted through the tool and parts; 
     FIG. 4 is a sectional front view taken along the line  4 — 4  of FIG. 1; 
     FIG. 5 is a partial sectional side view of the outer shaft of the temporary fastener of FIG. 3; 
     FIG. 6 is a sectional plan view taken along the line  6 — 6  of FIG. 5; 
     FIG. 7 is a front view of a portion of the clamp of FIG. 1 illustrating the sleeve member in greater detail; 
     FIG. 8 is a plan view of the sleeve member of FIG. 7; 
     FIG. 9 is a front view of a portion of the clamp of FIG. 1 illustrating the socket in greater detail; and 
     FIG. 10 is a plan view of the socket of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, a portion of an aircraft wing is generally identified by reference numeral  10 . Wing  10  includes a panel assembly  12  and structural members  14  (only one of which is visible). Panel assembly  12  generally includes multiple layers of panels  16 . Panels  16  and structural members  14  are held together by a plurality of fasteners  18 . A drill jig  20  is used to ensure the correct placement of fasteners  18 . Briefly, drill jig  20  has various apertures  22  provided to align a drill (not shown) when forming a series of panel apertures  26 . Generally, drill jig  20  is constructed for each specific application or location on the outer portions of an aircraft. Drill jig  20  is essentially a plate of steel or similar material with the apertures  22  formed at locations that correspond to the desired locations for the fasteners  18  that are used to assemble the panels  16  to one another and/or to the structural members  14 . A clamp  30  in accordance with a preferred embodiment of the present invention is used to secure drill jig  20  to panel assembly  12  as discussed below. 
     Referring now to FIG. 2, the clamp  30  is shown in greater detail. Clamp  30  includes a temporary fastener  32  which is hidden therein when the clamp  30  is secured to the panel assembly  12 , a sleeve member  34  and a socket  36 . Temporary fastener  32  may comprise a CLECO™ fastener available from Monogram Aerospace Fasteners of Los Angeles, Calif. Referring to FIG. 3, temporary fastener  32  is shown in greater detail. Temporary fastener  32  includes an outer shaft  38 , a spindle  40 , a draw bar  42 , and a wedge  44 . Outer shaft  38  is a generally annular member that includes a lower end surface  46  that is generally parallel to an upper end surface  48 , a bore  50  and an inner shoulder  52  formed as part of a recess  53 . Bore  50  extends axially through the body of outer shaft  38  opening onto both the lower end surface  46  and the shoulder  52 . Recess  53  has a diameter D 1  at upper end surface  48  that is larger than a diameter D 2  of the bore  50 . Also preferably, outer shaft  38  includes an annular recess or groove  54  near upper end surface  48  and within the recess  53 . A snap ring  56  can be inserted into annular recess  54 , as will be discussed further below. 
     Spindle  40  is an annular member having an external surface  58  with a groove  60  formed therein. A threaded bore  62  is formed axially through the spindle  40 . The spindle  40  has a thrust end surface  64  that is parallel a torque end portion  66 . Draw bar  42  has threads  68  formed on a first portion  70  and a pair of tine-like elements at a second portion  74  defining two prongs  76 . Draw bar  42  is threadably engaged within the threaded bore  62  of spindle  40 . The torque end portion  66  of spindle  40  protrudes from upper end  48  of the outer shaft  38 . Spindle  40  is inserted into bore  50  so that thrust end surface  64  abuts inner shoulder  52  within the recess  53 . Snap ring  56  can then be inserted into annular recess  54  and groove  60 . Thus provided, spindle  40  and outer shaft  38  are coupled for rotation therebetween while snap ring  56  and the interference between thrust end surface  64  and inner shoulder  52  resists axial translation between spindle  40  and outer shaft  38 . 
     With specific reference to FIGS. 4,  5 , and  6 , wedge  44  is formed to extend from outer shaft  38  so as to prevent rotation of draw bar  42 . In operation, rotation of spindle  40  causes axial translation of draw bar  42  relative to outer shaft  38 . 
     As best seen in FIG. 3, spindle  40  can be rotated in a first direction so as to cause the second portion  74  of draw bar  42  to move outwardly from outer shaft  38  in the direction of arrow A and beyond wedge  44 . In this position, the two prongs  76  of second portion  74  move inwardly toward one another due to their geometry and the characteristics of the material (preferably steel) from which the draw bar  42  is made (i.e., the prongs  76  are resiliently biased toward one another). 
     In order to attach temporary fastener  32  to panel assembly  12 , the second portion  74  of draw bar  42  is inserted in panel aperture  26 . When the second portion  74  is fully inserted in panel aperture  26 , prongs  76  extend beyond panel assembly  12 . Spindle  40  can be rotated in a second direction opposite to the first direction to cause axial translation of draw bar  42  in a direction opposite to that of arrow A, wherein prongs  76  move toward outer shaft  38  and panel assembly  12 . While moving toward outer shaft  38 , prongs  76  are forced apart due to the interference with wedge  44 . When prongs  76  contact panel  16  (FIG.  4 ), a gripping portion  78  of each prong  76  contacts the surface of panel  16  that surrounds panel aperture  26 , thus binding panels  16  together with temporary fastener  32 . As spindle  40  is rotated further in the second direction, panels  16  of panel assembly  12  are tightly clamped between the prongs  76  and the outer shaft  38 , thus securing fastener  32  to the panel assembly  12 . While FIG. 3 illustrates that temporary fastener  32  can be installed within panel aperture  26  after drill jig  20  is positioned adjacent panel assembly  12 , one of ordinary skill in the art will recognize that temporary fastener  32  can be installed within panel aperture  26  before drill jig  20  is positioned adjacent panel assembly  12 . 
     With specific reference to FIGS. 4, and  7 - 10 , clamp  30  further includes the sleeve member  34  and the socket  36 . Sleeve member  34  is preferably an annular portion with a concentric internal threaded bore  80 , a top end  82 , a recess  83 , a bottom end  84 , a threaded outer surface  86  that intersects bottom end  84 , and an outer torque surface  88  that intersects the top end  82 . 
     With reference to FIGS. 4,  9 , and  10 , socket  36  is preferably an elongated annular portion that includes an inner surface  90 , an outer surface  92 , an adjustment end  94 , and a clamping end  96 . Inner surface  90  opens into a threaded bore  100  which in turn opens onto adjustment end  94 . The threads of bore  100  couple with threaded outer surface  86  so as to allow sleeve member  34  and socket  36  of clamp  30  to releasably couple while allowing for axial adjustment therebetween. Preferably, outer surface  92  is provided with flat portions  104  to allow socket  36  to be rotated with a tool (not shown) such as an open end wrench. In operation, sleeve member  34  can be held at torque surface  88  with a hand or a tool while socket  36  is rotated. In this manner, socket  36  can be axially adjusted relative to sleeve member  34 , temporary fastener  32 , and panel assembly  12 . 
     Turning now to the operation of clamp  30 , temporary fastener  32  is installed onto panel assembly  12  as described herein. Preferably, a plurality of temporary fasteners  32  are installed in an arrangement that aligns with the arrangement of apertures  22  within drill jig  20 . Drill jig  20  is then positioned adjacent panel assembly  12  with each temporary fastener  32  extending through one aperture  22 . A plurality of the clamps  30  are then installed, one at a time, onto the draw bar  42  of each temporary fastener  32  with each clamp  30 , internal threaded surface  80  of sleeve member  34  threaded onto its associated draw bar  42  preferably at least three full thread engagements. Threaded bore  100  of socket  36  is then threaded onto threaded outer surface  86  of sleeve member  34  until clamping end  96  contacts drill jig  20 . Socket  36  can then be further rotated until clamping end  96  applies a sufficient amount of pressure on drill jig  20  to prevent relative movement between drill jig  20  and panel assembly  12 . In this manner, clamp  30  is adjustable to accommodate drill jigs with different thicknesses “t” (as indicated in FIG. 3) and modification of temporary fastener  32  is not necessary. After drill jig  20  is properly oriented with respect to panel assembly  12 , additional panel apertures  26  can be drilled using apertures  22  to ensure proper orientation. Additional clamps  30 , fasteners  18  or temporary fasteners  32  can be installed in panel apertures  26  as desired. When all the required panel apertures  26  have been drilled, drill jig  20  can be removed by removing the sockets  36  of clamps  30 . Temporary fasteners  32  can be removed and replaced with fasteners  18  to complete the assembly of panel assembly  12 . 
     The clamp  30  thus forms a means for quickly and easily operating in connection with a conventional fastener to enable a tool jig to be securely clamped to a panel assembly in a quick and easy manner. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.