US 8,011,560 B2 · Apparatus and method of solid-state welding

Abstract

The present invention provides an apparatus and improved method of friction stir spot welding that assures a predetermined bottom thickness and a reduction in variation in a series of resultant spot welds. The advantage of the present invention lies in that the plunge distance is controlled from the top plane of the anvil against which the bottom thickness is specified, and systematically adjusted to account for changing system parameters, such as, but not limited to, deflection and thermal expansion of the weld gun. The present invention also provides for improved and controlled weld quality through implementation of a dwell operation or dwell operations, whereby weld heat input is manipulated by causing the weld tool to dwell in a dwell region or at a desired depth or depths within the workpiece(s) for a predetermined time interval to achieve desired mechanical properties of the resultant weld joint.

Claims25

Dependent claims

A method for assuring a predetermined bottom thickness at an actual position in an operating region of at least one workpiece by a friction stir spot welding system having a weld gun, comprising:

monitoring system deflection occurring substantially along a rotational axis of the weld gun;
determining a zero position;
calculating a plunge distance relative to said determined zero position based upon at least a predetermined stack-up thickness, the bottom thickness, and said monitored system deflection;
causing a weld tool to enter the operating region at a predetermined plunge force and a predetermined plunge speed and causing relative rotational movement about said rotational axis between said weld tool and the at least one workpiece, while plunging up to said plunge distance, whereby pressure and frictional heat is generated, thereby causing the material in the operating region to plasticize;
and
causing said weld tool to exit the operating region after said bottom thickness has been reached, wherein the operating region is allowed to cool and the plasticized material to harden, thereby completing a single weld on the workpiece.

3 more elements

A method of achieving a predetermined bottom thickness in joining a plurality of workpieces defining a joining region therebetween by a friction stir spot welding system having a weld tool coaxially opposed to an anvil operatively connected to a weld gun, comprising:

determining a system deflection for a predetermined plunge force, wherein said system deflection occurs substantially along rotational axis of the weld tool;
determining and calibrating a zero position;
monitoring weld gun growth to determine if said weld gun growth exceeds a predetermined tolerance;
compensating the friction stir spot welding system in response to said weld gun growth exceeding said predetermined tolerance;
calculating a plunge distance relative to said zero position based upon at least a stack-up thickness, the bottom thickness, and said system deflection;
causing the weld tool to enter the joining region to reach said plunge distance at said plunge force and a predetermined plunge speed;
causing relative rotational movement about said rotational axis between the weld tool and the workpieces, whereby pressure and frictional heat is generated, thereby causing the joining region to achieve a plasticized condition;
promoting coalescence in the joining region;
and
causing the weld tool to exit the joining region after said bottom thickness has been reached, wherein the joining region is allowed to cool and the plasticized condition to reverse, thereby completing a single weld on the workpiece.

7 more elements

Dependencies are inferred from the claim text.

Apparatus and method of solid-state welding

Life of this patent

Apparatus and method of solid-state welding

Life of this patent

Abstract

Claims25