Abstract: A device (1) for socket-deforming an end of a tube, for example a tube of a heat exchanger, and for cutting that tube to a desired length, the cutting taking place at the end to be deformed. The The device (1) comprises a deformation and cutting member (5) to be inserted into the tube to be worked, the member (5) comprising deforming means (15) arranged to at least locally modify the inner diameter of the deformation and cutting member (5) by varying its perimetral dimensions, said deforming means (15) being arranged to cooperate, for effecting said dimensional variation, with actuator means (40) with a movable support (12), the deforming elements carrying cutting elements (31) for separating an end tube portion by acting from the inside of the tube without chip removal, in order to obtain a deformed tube of the required length.