a mechanically welded frame 13 which supports the various parts of the winder and their movement device revolving mandrel 14 is composed of two axially spaced cylindrical half mandrels not separately shown made for example of stainless steel rotated together by a motor preferably a direct current motor or each independently driven in rotation the two motors then being connected by a device for synchronization in relation to one another these two half mandrels can be separated from one another to permit the ejection of a shaped shell to do this they are each equipped with a device for driving the same in translation along its axis this device consisting of a hydraulic jack which controls the movement of the support of a half mandrel and its motor heating of the mandrel is provided by a bundle of electrical resistors distributed inside the mandrel and spaced as a function of its diameter while the felt is wound around the mandrel counterrollers 15 15 39 15 34 16 16 39 and 16 34 exert a slight pressure on the outer surface of the shell as fig2 and 3 in particular show rotationally driven counterroller 15 is mounted on an axis fixed on a support plate 17 itself hinged for rotation around axis 18 which is connected to a stationary plate 19 counterroller 15 can therefore describe the path of circle 20 passing through the axis of symmetry of the mandrel this movement of support plate 17 is controlled by a rotary hydraulic jack 21 to do this a point a of plate 17 is connected by a connecting rod 22 to an end d of a shaft 23 rotatable around fixed axis e this.