Core winder with magnetic support for the winding spindle

1. A machine to produce tubes by winding one or more strips of web material, comprising: a stationary bearing structure; a forming spindle supported at a proximal end by said stationary bearing structure and, around which at least one strip of web material is wound; a winding unit to wind said at least one strip of web material around the forming spindle and form therewith a tubular article, said tubular article advancing in a forward direction along said forming spindle; a cutting unit to cut the tubular article into a plurality of tubes which are removed from the forming spindle at a distal end of the forming spindle, said distal end being opposite said proximal end; and at least one magnetic support device supporting said forming spindle and including a plurality of first magnets which are stationary and which form a first set of magnets, arranged annularly around an axis of the forming spindle, and supported by said stationary bearing structure, and a plurality of second magnets, which form a second set of magnets, carried by the forming spindle and arranged around the axis of the forming spindle and oriented with respect to the first set of magnets so as to generate, with said plurality of first magnets, magnetic forces mutually cooperating to reduce flexural deformations of the forming spindle; wherein said magnetic support device is stationary with respect to the bearing structure and said magnetic support device is stationary with respect to the forming spindle and is located downstream of the cutting unit with respect to said forward direction of the tubular article along said forming spindle, between said cutting unit and said distal end of the forming spindle.

2. The machine as claimed in claim 1 , wherein said magnetic support device is arranged in proximity of a free end of said forming spindle.

3. The machine as claimed in claim 1 , wherein said plurality of second magnets are permanent magnets.

4. The machine as claimed in claim 1 , wherein said plurality of first magnets are permanent magnets.

5. The machine as claimed in claim 1 , wherein a through opening for the tubular article is defined between said plurality of first magnets and said plurality of second magnets.

6. The machine as claimed in claim 5 , wherein said plurality of first magnets and said plurality of second magnets are substantially annular shaped.

7. The machine as claimed in claim 1 , wherein said bearing structure supporting said plurality of first magnets is fixed with respect to a frame of the machine.

8. The machine as claimed in claim 7 , wherein said plurality of first magnets and said plurality of second magnets are substantially annular shaped.

9. The machine as claimed in claim 1 , wherein said plurality of second magnets are mounted on the forming spindle so as to rotate around the axis of the forming spindle.

10. The machine as claimed in claim 1 , wherein said cutting unit includes at least one blade and the machine further includes a contrast member or a counter-blade which cooperates with the at least one blade of the cutting unit and slides along said forming spindle.

11. The machine as claimed in claim 10 , wherein said contrast member or said counter-blade is movable to a position substantially corresponding with said magnetic support device.