A spring package (100; 200; 300; 400; 500) for a vibration welding device, comprising: a. a first longitudinal bar (110; 210; 310) for a fixed connection to a frame of the vibration welding device, b. a second longitudinal bar being parallel to and movable with respect to the first longitudinal bar (110; 210; 310) as well as for a connection to a tool, wherein a first axis (103; 203) of the spring package (100; 200; 300; 400; 500) extends halfway between and parallel to the longitudinal axis of the first (110; 210; 310) and second longitudinal bar, c. a plurality of leaf springs (130; 230) each of which is connected with a first end to the first longitudinal bar (110; 210; 310) and with a second end to the second longitudinal bar, wherein a second axis of the spring package (100; 200; 300; 400; 500) extends perpendicular to the first axis (103; 203) as well as, in an inactive state of the spring package (100; 200; 300; 400; 500), parallel to the plurality of leaf springs (130; 230) so that a spring center line extends, in the inactive state of the spring package (100; 200; 300; 400; 500), parallel to the second axis in the middle of the leaf spring (130; 230), and d. each of the plurality of leaf springs (130; 230) comprises adjacent to the first (110; 210; 310) and/or second longitudinal bar a first portion (134; 234) consisting of at least one radius (136; 236, 238; 340) so that the first portion (134; 234) is formed concave with respect to the spring center line, wherein e. the first portion (134; 234) transitions continuously into a second portion (142; 242; 342), and the second portion (142; 242; 342) transitions continuously into a center portion (144; 244) arranged adjacent the first axis (103; 203) so that a thickness of the respective leaf spring (130; 230) is at the lowest in the center portion (144; 244), especially at the first axis (103; 203), characterized in that f. the second portion (142; 242; 342) is formed convex with respect to the spring center line. a. a first longitudinal bar (110; 210; 310) for a fixed connection to a frame of the vibration welding device, b. a second longitudinal bar being parallel to and movable with respect to the first longitudinal bar (110; 210; 310) as well as for a connection to a tool, wherein a first axis (103; 203) of the spring package (100; 200; 300; 400; 500) extends halfway between and parallel to the longitudinal axis of the first (110; 210; 310) and second longitudinal bar, c. a plurality of leaf springs (130; 230) each of which is connected with a first end to the first longitudinal bar (110; 210; 310) and with a second end to the second longitudinal bar, wherein a second axis of the spring package (100; 200; 300; 400; 500) extends perpendicular to the first axis (103; 203) as well as, in an inactive state of the spring package (100; 200; 300; 400; 500), parallel to the plurality of leaf springs (130; 230) so that a spring center line extends, in the inactive state of the spring package (100; 200; 300; 400; 500), parallel to the second axis in the middle of the leaf spring (130; 230), and d. each of the plurality of leaf springs (130; 230) comprises adjacent to the first (110; 210; 310) and/or second longitudinal bar a first portion (134; 234) consisting of at least one radius (136; 236, 238; 340) so that the first portion (134; 234) is formed concave with respect to the spring center line, wherein e. the first portion (134; 234) transitions continuously into a second portion (142; 242; 342), and the second portion (142; 242; 342) transitions continuously into a center portion (144; 244) arranged adjacent the first axis (103; 203) so that a thickness of the respective leaf spring (130; 230) is at the lowest in the center portion (144; 244), especially at the first axis (103; 203), characterized in that f. the second portion (142; 242; 342) is formed convex with respect to the spring center line.