A shearing device for fragmenting a metal strip includes two counter-rotating drums facing one another, a drive device connecting the drums and synchronising their rotation speed, and at least one pair of drum-supported blades. The blades engage by shearing effect during drum rotation to cut the waste. The blades of the pair have, from the cutting edge thereof, planar surfaces, referred to as overlapping surfaces, overlapping and facing one another during the shearing between blades, each blade being secured transversely to the drum, at an angle to the axis of rotation of the drum, so the plane through the overlapping surface of the blade forms an angle with the axis of rotation of the corresponding drum, producing gradual shearing. The overlapping surface of each blade is tilted so the plane passing through the overlapping surface does not intersect the rotational axis of the drum on its active width.