A variety of clamping devices are available for applying clamping force to a workpiece in an area near a manufacturing tool operating on the workpiece. The application of clamping forces near the manufacturing tool may reduce the need for complicated or cumbersome external clamping tools that may be needed in processes such as friction stir welding (FSW), to locate the parts being welded, prevent part separation during welding and react to process loads generated during the welding process.
One clamping device suitable for use with a FSW machine is disclosed in US Patent Application Publication Number 2005/0092817 published May 5, 2005, and assigned to The Boeing Company. In this prior patent application, the clamping device is mounted on a spindle head that carries the FSW tool. The clamping device is constrained to mechanically follow the path of the FSW tool spindle. The spindle head is mounted on a machine tool arm that moves along any of 3 orthogonal axes in which the weld path, and thus the movement of the clamping device, is straight. In some applications, however, complex curvatures of workpieces require more complicated movements of the FSW tool as well as the clamping device. In these more complicated workpiece geometries, the tool path may vary with the changing slope and contours of the workpiece. As a result, the clamping device may not always “track” with the FSW tool to apply clamping force when and where it is required.
Accordingly, there is a need for a workpiece clamping apparatus that is mounted on a common support with a tool, but yet can be moved independently of the tool so that clamping force can be applied at the desired workpiece locations regardless of the orientation of the tool or the support. It would also be desirable to provide a clamping apparatus and related method that coordinates the independent movement of the clamping device with movement of the tool. Embodiments of the disclosure are intended to satisfy these needs.