Tool clamp and method

[0002] The present invention relates generally to a clamp used to align and secure a tool to at least one part.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0010] 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;

[0011] 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;

[0012] 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;

[0013] FIG. 4 is a sectional front view taken along the line 4—4 of FIG. 1;

[0014] FIG. 5 is a partial sectional side view of the outer shaft of the temporary fastener of FIG. 3;

[0015] FIG. 6 is a sectional plan view taken along the line 6—6 of FIG. 5;

[0016] FIG. 7 is a front view of a portion of the clamp of FIG. 1 illustrating the sleeve member in greater detail;

[0017] FIG. 8 is a plan view of the sleeve member of FIG. 7;

[0018] FIG. 9 is a front view of a portion of the clamp of FIG. 1 illustrating the socket in greater detail; and

[0019] FIG. 10 is a plan view of the socket of FIG. 9.

[0020] 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.

[0021] 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 D₁at upper end surface 48 that is larger than a diameter D₂of 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.

[0022] 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.

[0023] 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.

[0024] 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).

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.