Patent ID: 9095926
Filing Date: 2015-08-04
Classification: B23K

Abstract:
1. A method for friction stir spot welding comprising contacting an object to be welded with: a cylindrical pin member as a rotating tool configured to rotate about an axis and be advanceable and retractable in the axial direction, and a tubular shoulder member configured to surround the pin member, rotate coaxially with the pin member, and be advanceable and retractable in the axial direction; wherein: the object to be welded has a front surface facing the pin member and the shoulder member; the pin member and/or the shoulder member are configured to advance and retract to be brought into contact with the front surface of the object to be welded and to adjust a press-fit depth of the pin member and/or the shoulder member from the front surface of the object to be welded; and the pin member and the shoulder member are configured during the entire welding process so that a cross-sectional area of a front end surface of the pin member times a distance the pin member advances or retracts from the front surface of the object to be welded is substantially equal to a cross-sectional area of a front end surface of the shoulder member times a distance the shoulder member retracts or advances from the front surface of the object to be welded.