Machine for the production of tubes by winding strips of weblike material
The machine for producing tubes includes a winding spindle around which strips of weblike material are wound to form the tube, which is made to advance along the spindle; a device for supply and winding of the strips around the spindle, and at least one knife for cutting lengths of the tube being formed. The knife is provided with a reciprocating movement parallel to the spindle. There is moreover envisaged a counter-knife within the tube being formed, provided with a movement of translation synchronized to the movement of translation of the knife. The counter-knife is magnetically constrained to a mover member, which transmits the motion to the counter-knife.
1. A machine for producing tubes by winding strips of web material, comprising:
a winding spindle, around which are wound said strips to form said tube that is made to advance along said spindle;
a device for supplying and winding said strips around said spindle;
at least one knife for cutting lengths of said tube being formed, said knife being provided with a reciprocating movement parallel to said spindle; and
a counter-knife within the tube being formed, provided with a movement of translation synchronized with a movement of translation of said knife; wherein said counter-knife is constrained magnetically to a mover member that transmits the movement of translation to said counter-knife;
wherein said knife is supported by a mobile carriage with reciprocating motion parallel to said spindle; and wherein said mover member is fixed with respect to the carriage that supports the knife.
2. The machine according to claim 1 , further comprising first magnets arranged on said carriage, said first magnets being arranged on an outside of the tube being formed and adjacent thereto; and second magnets constrained to said counter-knife arranged inside said tube, wherein magnetic fields of said first magnets and said second magnets interact so that the counter-knife is drawn magnetically by the carriage that supports the knife.
3. The machine according to claim 2 , wherein said first magnets are set with polarities oriented according to a direction orthogonal to a direction of alignment of polarity of said second magnets.
4. The machine according to claim 3 , wherein said first magnets and said second magnets are configured and set such that force of mutual attraction between the first magnets and the second magnets does not hinder rotation of the counter-knife about an axis of the spindle.
5. The machine according to claim 2 , wherein said first magnets and said second magnets are configured and set such that force of mutual attraction between the first magnets and the second magnets does not hinder rotation of the counter-knife about an axis of the spindle.
6. The machine according to claim 2 , wherein said counter-knife is carried by a slider constructed and arranged to slide on a guide rod fixed with respect to the spindle and coaxial thereto.
7. The machine according to claim 1 , wherein said counter-knife is carried by a slider constructed and arranged to slide on a guide rod fixed with respect to the spindle and coaxial thereto.
8. The machine according to claim 7 , wherein said slider and said counter-knife are able to rotate freely about an axis of the guide rod.
9. The machine according to claim 7 , wherein said counter-knife is constructed and arranged to turn with respect to said slider.
10. The machine according to claim 1 , wherein said second magnets are annular.
11. The machine according to claim 1 , wherein said second magnets are permanent magnets.
12. The machine according to claim 1 , wherein said first magnets are permanent magnets.
13. The machine according to claim 1 , wherein said first magnets are carried by an annular structure fixed with respect to said carriage and surrounding the axis of said spindle.
14. The machine according to claim 13 , wherein said first magnets are set about the axis of the spindle.
15. The machine according to claim 1 , wherein said first magnets have a plate-like configuration.
16. The machine according to claim 1 , wherein said first magnets are set in pairs.
17. The machine according to claim 1 , wherein said second magnets are set in pairs.
18. The machine according to claim 1 , wherein said first magnets and said second magnets are set at a distance from said knife.