Apparatus for manufacturing cardboard tubes

Claim 1

A machine for the manufacture of tubes of cardboard or the like sheet material that have a length substantially greater than their width, comprising a core means reproducing the inner shape of the tube to be formed, advancing means for advancing a sheet to be formed along a generatrix of said core means, guide means for ensuring the exact disposition of the sheet on the generatrix of the core means, holding means for holding the sheet against the generatrix of the core means, two shaping jaws each reproducing about half the outer profile of the tube, the jaws being mounted for rotation around an axis from an initial position to an operative position in which each jaw presses half of the sheet against the outer surface of the core means, the movements of the jaws being phased so as first to compress one half of the sheet against the core and successively the other half to cause superimposing of the free edges of the sheet to be joined together, a presser means arranged to act to press together the two said edges when overlapped to join same together, retractable thrust means for detaching tubes from the inner core upon return of the jaws to their mutual positions, and support means for preventing the bending of the core during the pressing together of the overlapped edges by the presser means, said retractable thrust means of the tube comprising rods slidably located within complementary grooves in the core means, said rods being provided with thrust wings which protrude from said grooves.