Abstract: An ultrasonic welding apparatus improved in its presser opposed to the working surface of the oscillated horn. The presser roller is provided with a recess on a surface facing the working surface and an elastic member made of rubber and bonded thereon for covering the recess so as to be satisfactorily deformed according to an overlapped thick portion of workpieces to be welded. This causes the pressing force applied around the thick portion to be uniform with a good result. The elastic member comprises a first layer made of foamed rubber and a second layer made of silicone rubber and covering the first layer. The elastic member is preferably split by plural slits perpendicular to the working surface.

Abstract: An ultrasonic seam welding apparatus for seam welding at least two sheet-like workpieces piled one above the other by imparting ultrasonic oscillation, including a machine frame, a converter-horn assembly which includes a horn having a circular flat surface perpendicular to, and concentric with, the longitudinal axis of the assembly for being oscillated in a parallel direction to the longitudinal axis of the assembly, a roller rotatably supported on the machine frame and having a peripheral surface being opposed to a radially biased position of the flat surface of the horn away from the axis thereof so as to hold the workpieces under pressure with the aid of spring means for urging the roller downwards between the peripheral surface of the roller and the flat surface of the horn. The seam welding is carried out by imparting the ultrasonic oscillation to the workpieces from the converter horn assembly with the aid of the roller while regularly feeding the workpieces in good manner.