Patent EP-2561948-A1 (EP)
Inventor: SCHENK TOBIAS
IPC: B23K37/053
Filed: 2011-08-24
Abstract: The method comprises centering a longitudinal axis of a tube (2) according to an internal geometry of a flange (3) and the tube on rotation axes of flange adapters by a clamping- and supporting disc, scanning a butt joint on an outer periphery of the flange and the tube during its rotation about the rotation axes by a sensor in a rotation direction, determining a current position of the butt joint by processing a sensor data with a transmitter, and transferring the data to the controller for regulating the position of the friction stir welding probe in x-, y- and z-direction. The method comprises centering a longitudinal axis of a tube (2) according to an internal geometry of a flange (3) and the tube on rotation axes of flange adapters by a clamping- and supporting disc, scanning a butt joint on an outer periphery of the flange and the tube during its rotation about the rotation axes by a sensor in a rotation direction, determining a current position of the butt joint by processing a sensor data with a transmitter, transferring the data to the controller for regulating the position of the friction stir welding probe in x-, y- and z-direction, starting and pressing a mold wedge adjusted to a diameter of the tube and the flange to the rotating flange-pipe-flange-element in alignment with a tangential plane extending horizontally by the rotation axes located above the butt joint when the flange-pipe-flange-element has a rotation of 355[deg] , where the rotation of the flange-pipe-flange-element is stopped when reaching an angular position of 365[deg] , moving a friction stir welding probe of a friction stir welding tool (30) in the mold wedge in a direction of tangential plane, leaving the mold wedge from the flange-pipe-flange-element, removing the finished flange-pipe-flange-element after releasing the clamping and supporting discs, and axially relaxing a movable clamping unit (6). The clamping unit is stretched along the rotation axes of the flange adaptors of the longitudinal axis. A reaction force for a contact force is applied by a weld pool associated with the butt joint in an inner side of the flange and the tube when the friction stir welding probe penetrates into the butt joint. A rotational speed of the flange-pipe-flange-element and the contact force of the friction stir welding probe are centrally set by a controller. The flanges and the tube are brought in contact with each other in a two-stage centering process in its butt position in which the flanges are fixed at the flange adapters so that the longitudinal axis coincides with the rotation axis of the respective flange adapters and then the longitudinal axis of the tube is centered on the rotation axes of the flange adapters coincident with the longitudinal axis of the flanges. Synchronous motors: are used as a direct drive (9) for the flange adapters; and drive the flange adapters in synchronization with the same rotational speed so that the butt joint of tube and the flange are simultaneously processed on both tube ends by the friction stir welding probes. The step of axially clamping the tube between the flanges is carried out pneumatically, where the contact force is generated by a pressure cylinder and adjusted in dependence of a dimensioning of the tube and the flanges to a value of 5000-8000 N. The clamping- and support disc is pneumatically, hydraulically or electrically operated. The clamping and support disc is applied, at a first clamped condition, in 65-70% of the inner periphery of the flange and tube in the butt area by primary jaws spaced each other by gaps, and, at a second clamped condition, in the entire inner periphery by a radial extension of secondary jaws in the gaps between the primary jaws towards the inner wall of the flange and tube during the clamping operation so that an end region of the clamping and supporting disc forms a closed surface for the weld pool and an abutment for the contact forces during the friction stir welding and for clamping against the inner wall of the tube and the flange. The secondary jaws are retracted from an area between the primary jaws for releasing the clamping- and supporting disc and then the primary jaws are radially opposite to the inner wall of the tube and the flange. An angular position of the rotation of the flange-pipe-flange element is determined by an angle position sensor of the direct drives and forwarded to the controller for initiating start-up and shut-down of the mold wedge. A laser scanner, an image-sensor or a line-laser is used as a sensor. Each friction stir welding probe is associated with the sensor. An independent claim is included for a plant for manufacturing a flange-pipe-flange-element using friction stir welding.