Patent ID: 7377416

Claim:
A method of ultrasonically welding a seam in a sheet, comprising: overlapping a first edge and a second edge of a sheet by an overlap length less than 1.8 mm, forming an overlap; applying an ultrasonic welding member to the overlap, the ultrasonic welding member comprising a main body, having a width of at least 10 mm, a substantially rectangular contact surface defined at one end of the main body, the contact surface having a first dimension in a range of 1.0-5.0 mm and a second dimension, perpendicular to the first dimension, in a range of 0.3-2.0 mm, the contact surface being defined at an end of a taper, the taper having a length of less than 5 mm between an edge of the main body and the contact surface, the taper defining four non-convex surfaces; and moving the ultrasonic welding member along the overlap along a welding process direction, wherein a dimension of the contact surface of the welding member perpendicular to the welding process direction is at least as long as the overlap length.