A adjusting nut is arranged on a threaded spindle. The adjusting nut supports a first double arm lever unit with a first and a second arm. A second double arm lever unit is pivotally mounted at its first arm through a connecting strip to the second arm of the first double arm unit. The second arm of the second double arm unit is pivotally mounted through a control rod unit to a rocker. This rocker supports a upper feeding roller which co-operates with a lower feeding roller for a feeding of a strip shaped blank. The first arm of the first double arm unit supports a bolt which projects into a elongate hole of a eccentrically supported rod.