Patent EP-2561951-A1 (EP)
Inventor: SCHENK TOBIAS
IPC: B23K20/12
Filed: 2012-08-21
Abstract: Producing a butt joint between rotationally symmetrical bodies, e.g. flange-pipe-flange, flange-pipe, or tube-pipe arrangements, using friction stir welding, comprises: fixing the rotationally symmetrical bodies on joint by clamping means, where a common longitudinal axis can be set into rotation by drive means; and carrying out local deformation of the butt region of the bodies which are retained using axial clamping forces by radially pressing and straightening the bodies using a centering, inner-shape-forming, straightening and clamping disk (15). Producing a butt joint between rotationally symmetrical bodies, e.g. flange-pipe-flange, flange-pipe, or tube-pipe arrangements, using friction stir welding, comprises: fixing the rotationally symmetrical bodies on joint by clamping means, where a common longitudinal axis can be set into rotation by drive means, while rotating shaft with retractable pressing force on each butt joint is connected with a rotating pin (70), which is pressable or retractable into or out of the butt region (18) relative to shaft, and a friction stir welding tool (30) deliverable in the x-, y- and z-directions softens and stirs the material regions of the butt together in a rotation. The reaction force for the contact pressure is applied by a spun and detachable weld pool under the butt against the inner wall of the body, and the rotational velocity of the body, the rotational speed and the pressing force of the pin and the shaft can be adjusted by a control center; carrying out local deformation of the butt region of the bodies which are retained using axial clamping forces by radially pressing and straightening the bodies using a centering, inner-shape-forming, straightening and clamping disk (15), where the centering force is boosted in the manner of a toggle lever to an inner-shape-forming force causing the local deformation, and the inner-shape-forming force is maintained in the butt region of the bodies until the end of the friction stir welding process. An independent claim is also included for a plant for producing the butt joint between rotationally symmetrical bodies by friction stir welding comprises clamping units, on each of which rotationally symmetrical body is fixed on a receptacle, formed by a direct drive disposed for rotation about its longitudinal axis coinciding with the rotational axis of the receptacle, where the clamping units are aligned in alignment with the longitudinal axis and span a common rotational axis, and the clamping units are fixed against each other for the axial clamping of rotationally symmetrical body between the rotationally symmetrical bodies on the receptacles to form butt joints by a drive movable on a guide rail pair, so that the clamped rotationally symmetrical body can perform a rotation about the longitudinal axis with the body fixed on the receptacle, a friction stir welding tool associated with each clamping unit, which is deliverable horizontally and vertically based on respective butt joint with a cross slide and exhibits a rotatable tool holder perpendicular to the longitudinal axis and accommodated by a housing, into which a friction stir welding pin comprising a shaft provided with a shoulder is inserted, a weld pool arranged in the interior of the body below the butt joint, and a controller which communicates with the direct drive of the receptacles and the drives for the friction stir welding tool for adjusting the pressing forces and the rotational speed of the body, and also the delivery of the friction stir welding tool and its speed of rotation. The weld pool is formed as a centering, inner-shape-forming, straightening and clamping disk for generating a coincident circularity and straightness in the butt region of the adjoining body. The tool holder is associated with a lifting plate, whose underside faces away from the tool holder and has a bearing, which comprises the shaft for rotatable mounting of the shaft in axial manner. At least two lifting means are provided for performing a lifting movement of the common lifting plate, and bearing, which are arranged symmetrically with respect to shaft between the upper side of the lifting plate facing the tool holder and the housing plate. The friction stir welding pin is arranged in axially displaceable manner relative to the shaft such that the tip of pin achieves a defined penetration depth in the butt joint during performing the lifting movement of lift plate and bearing, depending on the thickness dimension of the rotationally symmetrical body, and the position, shape and geometry of the butt joint.