A device for processing, in particular for ultrasound welding, of packaging sleeves and/or packagings includes at least two tools for processing, in particular for ultrasound welding, of packaging sleeves. Each tool has an operating region. The tools are supported in such a manner that there is produced between the operating regions a gap whose longitudinal direction corresponds to the transport direction of the packaging sleeves, and the tools are supported in such a manner that the size of the gap can be changed. In order also to enable continuous welding of the packaging sleeves in a reliable manner with changing material thicknesses, there is provided at least one parallel spring on which at least one of the tools is movably supported transversely relative to the transport direction of the packaging sleeves.

A work piece processing device includes a tool piece, a work piece holder and a servo-elastic actuator system having simultaneous precision force and position control that moves one of the tool piece and the work piece holder to the other of the tool piece and work piece holder.

A button-fastening upper die includes a die body, a button-holding member and a cylindrical elastic member arranged between the die body and the button-holding member. By providing the elastic member with an annular recess recessed radially outward from the inner surface e.g. at the middle of the surface, the elastic member is sectioned into a thin-walled section located radially outward from the recess and two or more thick-walled sections remaining above and below the recess and the thin-walled section.