Stack of folded hygiene products and method and apparatus for producing same

1. A method for producing stacks of individual web sections from a continuous web of material, comprising the steps of:

(a) directing the continuous web to a perforating station;

(b) perforating the continuous web at predetermined intervals and forming sheets of web material between consecutive perforation lines extending laterally across the continuous web, the perforating being carried out via at least one perforation element arranged at the circumference of a perforation roller;

(c) directing the continuous web to a cutting station;

(d) cutting at second predetermined intervals the continuous web into web sections via a cutting element acting against an anvil element, to generate a clear cut or a tab-bond;

(e) folding the web sections via a folding roll; and

(f) stacking the folded web sections to generate a stack of folded sheets; wherein

in step (b) the continuous web is frictionally held and transported at a controlled speed via a web tensioning device arranged upstream and downstream of the perforating station, wherein the web tensioning device comprises two rollers upstream of the perforating station, with a gap between the rollers and the continuous web such that the continuous web is not pinched between the rollers.

2. The method according to claim 1 , comprising, after step (e) and before step (f):

(e2) adding adhesive properties to the folded web sections.

3. The method according to claim 2 , wherein in step (e2) adhesive is selectively ejected onto the folded web sections.

4. The method according to claim 2 , wherein in step (e2) an adhesive strip or a hook and loop fastener element is applied onto the folded web sections.

5. The method according to claim 1 , wherein in steps (a) and (c), the continuous web is brought to a controlled speed.

6. The method according to claim 5 , wherein a first speed in step (a) and a second speed in step (c) are different.

7. The method according to claim 6 , wherein the second speed is higher than the first speed.

8. The method according to claim 1 , wherein in step (b) a circumferential speed V1 of the perforation roller is adjusted to be different to a transport speed V2 of the continuous web at a position at which the continuous web is perforated, the circumferential speed Viand the transport speed V2 being controlled to fixed values satisfying the equation: 0.4× V2≤V1≤1.4× V2.

9. The method according to claim 1 , wherein steps (a) to (d) are carried out in parallel for two separate continuous webs; and in step (e) the web sections formed from the two separate continuous webs are interfolded to form a stack of interfolded sheets.

10. The method according to claim 1 , wherein the continuous web of material is a hygiene or wiping material.

11. The method according to claim 1 , wherein the continuous web of material is selected from the group of paper towels, facial tissue, cosmetic tissue, napkins, kitchen towels, and toilet paper.

12. The method according to claim 1 , wherein the web tensioning device further comprises two rollers downstream of the perforating station, with a gap between the rollers and the continuous web such that the continuous web is not pinched between the rollers.

13. The method according to claim 1 , wherein the web tensioning device is designed to frictionally hold and transport the web at a controlled speed, the web tensioning device being an S-wrap around two rollers.

14. An apparatus for producing stacks of sheets from a continuous web of material, comprising:

a perforating station with a rotatable perforation roller comprising at least one perforation element arranged at the circumference of the perforation roller, wherein the at least one perforation element is adapted to generate a perforation line;

a cutting station comprising a cutting element and an anvil element, wherein the cutting element is adapted to generate a clear cut or a tab-bond;

a folding station with a folding roll;

a stacking station to form a stack of sheets; and

a web tensioning device arranged upstream and downstream of the perforating station, wherein the web tensioning device comprises two rollers upstream of the perforating station, with a gap between the rollers and the continuous web such that the continuous web is not pinched between the rollers.

15. The apparatus according to claim 14 , wherein the anvil element is a rotating anvil roller.

16. The apparatus according to claim 14 , wherein the cutting element is a reciprocating cutting knife operable via a cam mechanism to which the cutting knife is coupled.

17. The apparatus according to claim 14 , wherein the cutting element is an electrically operated reciprocating cutting knife.

18. The apparatus according to claim 14 , the perforation roller having several perforation knives distributed over the peripheral surface of the perforation roller, wherein at least one of the perforation knives is adapted to be selectively activated or to be put in an idle state.

19. The apparatus according to claim 14 , wherein

the at least one perforation element is helically arranged on the circumferential surface of the perforation roller.

20. The apparatus according to claim 14 , wherein

the web tensioning device is designed to frictionally hold and transport the web at a controlled speed, the web tensioning device being an S-wrap around two rollers.

21. The apparatus according to claim 14 , wherein

the cutting element is adapted to generate a tab-bond; and

the stacking station comprises a separating element to separate the web material at the tab bond.

22. The apparatus according to claim 21 , wherein

the separating element is a separating finger.

23. The apparatus according to claim 21 , the stacking station further comprising a counting device adapted to determine a length of a web section.

24. The apparatus according to claim 14 , wherein

the folding roll is operatively coupled to a source of sub-atmospheric pressure.

25. The apparatus according to claim 14 , wherein the continuous web of material is a hygiene or wiping material.

26. The apparatus according to claim 14 , wherein the continuous web of material is selected from the group of paper towels, facial tissue, cosmetic tissue, napkins, kitchen towels, and toilet paper.

27. The apparatus according to claim 14 , wherein the web tensioning device further comprises two rollers downstream of the perforating station, with a gap between the rollers and the continuous web such that the continuous web is not pinched between the rollers.