Patent Application
20060237888
This invention relates generally to clamping and, more specifically, to clamping during manufacturing operations.
During manufacturing work such as machining, routing, cutting, and welding, the workpiece is often held by clamps when a manufacturing tool engages it. Such clamps include bar clamps, C-clamps, vices, and other clamping tools. In manufacturing operations where a tool engages the workpiece with some force, clamping at fixed or distant locations may not be sufficient to hold the workpiece in position. As the tool moves, the distance between the manufacturing tool and the applied clamp or clamps may increase.
More specifically, in friction stir welding, a process that joins metals by thermoplastic deformation and inter mixing, plunging the friction stir welding tool into a weld line of a workpiece and moving the tool along the weld line can push the parts of the workpiece being welded away from the underlying structure, or away from each other. According, there is an unmet need for clamping systems that more securely engage a workpiece along a working area for a manufacturing tool.
The present invention is directed toward systems and methods for clamping along a workpiece. In one embodiment, a clamping system includes an elongated member adapted to be positioned across a workpiece, and an elongated bladder adapted to be positioned between the member and the workpiece. The bladder applies a clamping force to the workpiece when the bladder is inflated. In another aspect of the invention, the system includes a plurality of clamp supports, supporting clamp bars that bridge a workpiece. A high temperature hose bladder is positioned between the clamp bar and the workpiece. The hose bladder applies a clamping force to the workpiece when the hose is inflated. In accordance with other aspects of the invention, a method of clamping includes positioning a skin over a substructure, bridging the skin and substructure with an elongated clamp support, and inflating an elongated bladder between the clamp support and the skin, thereby clamping the skin to the substructure for welding or other manufacturing processes.
Preferred and alternate embodiments of the present invention are described in detail below with reference to the following drawings.
The present invention relates to systems and methods for clamping. Many specific details of certain embodiments of the invention are set forth in the following description and in
In this exemplary embodiment, the clamping system 20 includes a plurality of elongated bladder clamps 40 that partially or substantially bridge the skin 6 and substructure 4. The clamps 40 are supported at their ends 41 (
In this embodiment, the bladder clamps 40 are suitably curved to follow a curved contour in the underlying workpiece 10, permitting the skin 6 to be held tightly to the substructure 4 for manufacturing operations across the workpiece 10. When the clamps 40 are activated, as described below, a clamping force is applied in a line across the surface of the workpiece 10. By way of example, without limitation, the clamps 40 may bridge the workpiece 10 in pairs 39 with a distance d between the clamps 40. A manufacturing tool may be inserted between the members of the pairs 39 to engage the workpiece 10. The tool may also be moved across the workpiece 10. Working in pairs 39, the workpiece 10 is securely clamped on both sides of the manufacturing tool, in close proximity to the manufacturing tool (not shown) across any desired portion of the span of the workpiece 10.
The bladder clamps 40 include inflation tubes 49 for inflating inflatable bladders (not shown) on the underside of the clamps 40 as described below with reference to
In this embodiment, the clamps 40 include clamp bars 42 that bridge the workpiece 10. The clamp bars 42, by way of example, but not limitation, may be machined bars of ASTM-A36 steel curved to match the underlying contour of the workpiece 10. In alternate embodiments, the clamp bars 42 may be formed from any suitably rigid material. The clamp bars 42 include a distal surface 45 facing away from the workpiece, and a proximal surface 44 facing the workpiece 10. In this embodiment, a proximal (or lower) surface 44 of each bar 42 has a channel (or recess) 43 formed therein. The channel 43 may be machined, cast, or otherwise formed in the proximal surface 44 of the clamp bar 42. The channel 43 provides a space for holding an elongated inflatable bladder (or member) 48. The bladder 48 is inflated to apply clamping pressure to the workpiece 10 under each clamp bar 42 across the entire surface of the workpiece, or alternately, across a desired portion of the surface of the workpiece 10. In one particular embodiment, the bladder 48 is initially contained within the channel 43, and as the bladder 48 is inflated it expands outwardly from within the channel 43 to exert a clamping force on the workpiece 10. Subsequently, when it is deflated, the bladder 48 retracts back into the channel 43, where it is at least partially protected from damage or wear.
In one particular embodiment, the clamp bars 42 are approximately 1.5 inches in width and 1 inch in thickness. The channel 43 formed in the proximal surface 44 of the bar 42 may have a “C” cross-sectional shape, and may have a width of approximately 1.25 inches and a depth of approximately 1.0 inches. The bladder 48 partially nests up within the channel 43 within the proximal surface of the bar 42, and extends outward from the bar when the bladder 48 is inflated.
In one particular embodiment, the elongated bladder 48 is a silicon hose with NOMEX fiber manufactured by Presray Pneuma-seal of Pawling Engineered Products. The silicon bladder with NOMEX fiber retains approximately 80% of its strength at 400° Fahrenheit, permitting high temperature manufacturing operations to be undertaken on the workpiece 10 in close proximity to the clamps 40. By way of example, but not limitation, in friction stir welding applications of an approximately one-eighth inch aluminum skin to an underlying substructure, the bladders are suitably inflated between 10 and 80 psi, and the clamp bars 42 of each pair 39 of clamp bars 40 are positioned approximately 1.25 inches apart. A friction stir welding tool may then engage the workpiece 10 between the clamps 40 with the bladders 48 maintaining clamping pressure on the workpiece 10 despite the heat generated by the friction stir welding tool.
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 the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.
