RECONFIGURABLE LOW-PROFILE PNEUMATIC EDGE-CLAMP

SYSTEMS AND METHODS

FIELD OF THE INVENTION

This invention relates to systems and methods for securing a workpiece during a manufacturing operation, and more specifically, to pneumatic edge-clamp systems and methods that may be used, for example, in welding or other manufacturing operations.

BACKGROUND OF THE INVENTION

During many different types of manufacturing operations, it is necessary to secure the workpiece in position. For example, in the process of friction stir welding, a sheet aluminum panel is clamped against an aluminum substructure, such as an I-beam, to allow a high speed rotating spindle to engage the panel, causing friction-induced elevated temperatures which fuse the panel and substructure together.

One proven method of clamping the aluminum panel is to use commercially available pneumatic inflatable bladders which expand against the panel to restrain movement of the panel and press it firmly against the substructure. Such inflatable flexible bladders are typically contained in a low profile metal frame that is machined with an offset contour that matches the panel. The offset contour places the inflatable bladder slightly offset above the panel, allowing the flexible bladder to expand against and conform to the surface contour of the panel. A set of these metal frames can be placed nearby both sides of the friction stir welded joint to provide secure clamping on each side of the rotating spindle.

A problem may arise when die friction stir welded joint is located near the edge of the panel since there is no space on the outside edge of the joint for the typical metal frames which house die pneumatic inflatable bladders. Since it is desirable to have clamping force applied on both sides of the joint during the welding process, there is a need for an improved edge-clamping system that provides the desired clamping force on both sides of the joint during the welding process even near the edges of the panel.

SUMMARY OF THE INVENTION

The present invention provides pneumatic edge-clamp systems and methods for securing a workpiece during a manufacturing operation. Embodiments of the present invention may advantageously provide a low-profile edge-clamping system that operates with a short

displacement, conforms to the surface contour of the panel, provides quick actuation, and that is readily reconfigurable as needed.

In one embodiment, a clamping apparatus for applying a clamping force to a workpiece includes a beam member having a cavity disposed therein, and an inflatable member disposed within the cavity. The inflatable member is coupleable to a pressurization source. A clamping member is pivotably coupled to the beam member. The clamping member includes a first portion projecting at least partially over the cavity, and a second portion projecting laterally outwardly from the beam member over the workpiece. In operation, inflating the inflatable member applies a driving force to the first portion, rotating the clamping member, and applying a clamping force to the workpiece using the second portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described in detail below with reference to the following drawings.

FIGURE 1 illustrates a perspective view of components of a welding system formed in accordance with an embodiment of the present invention;

FIGURE 2 illustrates a cross-sectional view of a portion of the welding system shown in FIGURE 1;

FIGURE 3 illustrates an exploded view of an edge-clamp frame and seal formed in accordance with an embodiment of the present invention;

FIGURE 4 illustrates a perspective view of an edge-clamping component in accordance with an embodiment of the present invention;

FIGURE 5 is an enlarged, partially exploded isometric view of a portion of the edge-clamping component of FIGURE 4;

FIGURE 6 is an enlarged, partially exploded isometric view of another portion of the edge-clamping component of FIGURE 4; and

FIGURES 7 and 8 illustrate cross-sectional views of the clamping component of FIGURE 4 in non-clamping and clamping modes, respectively.

DETAILED DESCRIPTION

The present invention relates to pneumatic edge-clamp systems and methods for securing a workpiece during a manufacturing operation. Many specific details of certain embodiments of the invention are set forth in the following description and in FIGURES 1

through 8 to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that the present invention may be practiced without several of the details described in the following description.

FIGURE 1 illustrates a manufacturing system 18 in accordance with an embodiment of the present invention. In this embodiment, the manufacturing system 18 includes a controller 20, a pneumatic pump 19, and a clamping device 21. The controller 20 controls operation of the pneumatic pump 19 for supplying pressurized air to various components of the clamping device 21. The controller 20 may also control other components of the manufacturing system 18, including one or more tools 30 that perform manufacturing operations on one or more workpieces secured by the clamping device 21. In one embodiment, the tools 30 are welding components, such as friction stir welding heads or the like.

In one embodiment, the clamping device 21 includes one or more edge-clamp systems 26 and one or more pneumatic surface clamps 32 for securely positioning a first workpiece 24 with respect to a second workpiece 22 during the performance of the manufacturing operation {e.g. welding). The pneumatic surface clamps 32 and the edge-clamps systems 26 are attached to one or more fixture bases 28. As described more fully below, in one embodiment, the tools 30 may perform welding (e.g. friction stir welding) along pre-defined paths to securely bond the first and second workpieces 24, 22 together. In alternate embodiments, any other desired manufacturing operations may be performed.

FIGURE 2 illustrates a cross-sectional view of a portion of the manufacturing system 18 of FIGURE 1. As shown in FIGURE 2, in this embodiment, the pneumatic surface clamp 32 includes an inflatable seal 52 that, when inflated by the pump 19, applies pressure on the first workpiece 24, securely engaging the first workpiece 24 against the second workpiece 22. In one embodiment, the first workpiece 24 is a molded aluminum skin, such as that of a fuselage of an aircraft, and the second workpiece 22 is an aluminum stringer or beam suitable for use within an airframe. The structure and operation of the surface clamp 52 is described more fully, for example, in co-pending, commonly owned U.S. Patent Application No. 11/112,994 entitled "Inflatable Clamping Systems and Methods" filed on April 22, 2005, incorporated herein by reference. Various alternate embodiments of clamping apparatus that may be substituted for the surface clamp 52 are described, for example, in co-pending, commonly owned U.S. Patent Application No. 10/648,535 entitled "Adaptable Spring Force Clamping Apparatus and Methods" filed on August 25, 2003, incorporated herein by reference.

With continued reference to FIGURE 2, in this embodiment, the edge-clamp system 26 includes an edge-clamp device 56 operatively coupled to a beam 58. The edge-clamp- device 56 includes a clamp bar 62 rotatably attached to a retainer block 64 by a pivot pin 68. A securing bolt 66 attaches the retainer block 64 to the beam 58. In this embodiment, the beam 58 includes an approximately U-shaped cavity 78 for receiving an inflatable bladder (or seal) 60, and a plurality of threaded holes 80 (FIGURE 3) for receiving the securing bolt 66.

In operation, as the inflatable seal 60 is pressurized, the inflatable seal 60 applies pressure on a first portion of the clamp bar 62, rotating the clamp bar 62 about the pivot pin 68 and forcing a second portion of the clamp bar 62 downwardly to apply a clamping force F _c on the first workpiece 24. The edge-clamp system 26 thereby securely engages the first workpiece 24 against the second workpiece 22 during a manufacturing operation. In this embodiment, the tool 30 is placed between the edge-clamp system 26 and the surface clamp 34 in order to get the tool 30 as close as possible to a common edge of the first and second workpieces 22, 24.

Additional details of the edge-clamp system 26 are shown in FIGURE 3. In this embodiment, the U-shaped cavity 78 extends from a first end 86a of the beam 58 to a second end 86b of the beam 58. The inflatable seal 60 is received within the cavity 78 and includes a stem 76 that passes through an opening in the cavity 78. The stem 76 is coupled to the pump 19. The inflatable seal 60 may be attached to the base of the cavity 78 using, for example, a suitable adhesive. In one particular embodiment, the inflatable seal 60 is a Presray Pneuma-seal ^® commercially-available from the Pawling Corporation of Pawling, New York.

Di the embodiment shown in FIGURE 1, each end 86a and 86b of the beam 58 includes through holes 87 for receiving the bolts 36 that secure the beam 58 onto the respective fixture bases 28. Alternately, each end 86a, 86b of the beam 58 includes a pair of threaded members 84 to secure the beam 58 to the bases 28 and to prevent movement of the beam 58 during a clamping process.

FIGURE 4 illustrates a perspective view of the edge-clamp system 26 of FIGURE 1. In this embodiment, a plurality of edge-clamp devices 56 are coupled to the beam 58, and a plurality of seal restriction members 90 are coupled to the beam 58 and interspersed between the edge-clamp devices 56. More specifically, as shown in the partially exploded view of FIGURE 5, the securing bolt 66 is threaded through the retainer block 64 and received by one of the threaded holes 80 in the beam 58. In one embodiment, the edge-clamp devices 56 (and seal restriction members 90) are evenly distributed along the beam 58, however, in alternate

embodiments, the edge-clamp devices 56 (and seal restriction members 90) may be non- uniformly distributed along the beam at desired locations depending upon the requirements of the manufacturing operation. In further embodiments, a greater or lesser number of edge-clamp devices 56 (and seal restriction members 90) may be employed than are shown in FIGURE 4.

FIGURE 6 is an enlarged partially-exploded view of a portion of the edge- clamp device 26 of FIGURE 4. In this embodiment, the seal restriction member 90 is coupled to the beam 58 by a bolt 92 that passes through a hole in the seal restriction member 90 and is received by one of the threaded holes 80. In alternate embodiments, the seal restriction members 90 may be coupled to the beam 58 using any suitable attachment device, or alternately, may be integrally-formed with the beam 58. The seal restriction member 90, when attached to the beam 58, is configured to extend at least partially over the U-shaped cavity 78 of the beam 58, thereby restricting expansion of the inflatable seal 60 between the edge-clamp devices 56.

As shown in FIGURE 6, in one embodiment, the seal restriction member 90 includes a first portion 91 that contacts the beam 58, and a second portion 93 that extends over the inflatable seal 60 disposed within the U-shaped cavity 78. The first portion 91 may have a greater thickness than the second portion 93. hi this embodiment, the thicknesses of the first and second portions 91, 93 may be selected to allow the inflatable seal 60 to expand a pre-defined amount that would in turn allow the clamp bar 62 of the edge-clamp device 56 to rotate a pre-set amount, thereby putting proper pressure on the first workpiece 24.

FIGURE 7 shows an enlarged cross-sectional view of a portion of the edge clamp system 26 of FIGURE 4. Ih this embodiment, the clamp bar 62 includes a non-abrasive tip 90 that engages the first workpiece 24 during the clamping operation. In one embodiment, the non-abrasive tip 90 is a polymer tip that reduces marring or scratching of the first workpiece 24 and reduces thermal conduction from the first workpiece 24 into the clamp bar 62 during manufacturing operations (e.g. welding). In this embodiment, the tip 90 is attached to the clamp bar 62 by an attachment pin 92. Alternately, the tip 90 may be adhesively attached, or attached by any other suitable means to the clamp bar 62.

FIGURE 8 illustrates the rotational movement of the clamp bar 62 about the pivot pin 68 as the inflatable seal 60 is being pressurized. More specifically, as the inflatable seal 60 is pressurized, a driving force Fd is applied by the inflatable seal 60 against the first end 62a of the clamp bar 62, thus forcing the clamp bar 62 to rotate (generally depicted as arrow R) about the pivot pin 68. In turn, the second end 62b of the clamp bar 62 is forced downwardly,

causing the tip 90 to apply the clamping force Fc onto the first workpiece 24. The clamping force Fc is maintained on the first workpiece 24 until the seal 60 is deflated.

Embodiments of the present invention may provide significant advantages over the prior art. For example, as depicted in FIGURE 2, embodiments of edge-clamp systems 26 may allow an edge of a workpiece to be secured using less surface area of the workpiece than alternate clamping systems {e.g. pneumatic surface clamp 32), thereby allowing room for the tool 30 while properly securing the workpiece during the performance of manufacturing operations near the edge. Also, embodiments of the invention may provide a low-profile edge- clamping system that operates with a short displacement, thereby performing the desired clamping function without interfering with the performance of the manufacturing operations. Furthermore, as shown in FIGURES 1 and 4, embodiments of the invention may advantageously be configured to conform to a variety of surface contours, and may be readily reconfigurable by adjustment of the locations of the edge-clamp devices 56, the retaining members 90, and the shape of the beam 58. Finally, embodiments of the invention may provide relatively quick actuation in comparison with alternative clamping systems.

While preferred and alternate embodiments of the invention have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of these preferred and alternate embodiments. Instead, the invention should be determined entirely by reference to the claims that follow.