Method for producing coreless rolls of paper
A method of forming a roll of convolutely wound web material. The method includes winding web material around an elongated mandrel to form a roll of convolutely wound web material. The mandrel is substantially axially elastic and formed of material having a tensile yield strength divided by elastic modulus greater than 2.0%, and more preferably 2.5%. The mandrel is preferably radially complaint. The method further includes removing the mandrel from the roll. A further method includes winding web material around an elongated mandrel to form a roll of convolutely wound web material, the mandrel being comprised of material having a tensile yield strength divided by elastic modulus greater than 2.0%, and then longitudinally elongating the mandrel.
1. A method of forming a roll of convolutely wound web material comprising the steps of:
a) winding a web material around an elongated mandrel to form a roll of convolutely wound web material, the mandrel being substantially axially elastic and comprised of material having a tensile yield strength divided by elastic modulus greater than 2.0%; and
b) removing the mandrel from the roll.
2. The method of claim 1 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% has at least one of the following properties:
a) a glass transition temperature less than 60° F.;
b) a mass density (g/cc) less than 1.50;
c) a tensile elastic modulus less than 2,000,000 psi;
d) a tensile yield strength less than 50,000 psi;
e) a structure (% crystallinity) greater than 25;
f) a Poisson's ratio greater than 0.30.
3. The method of claim 1 in which the mandrel is moved longitudinally during the step of removing the mandrel from the roll.
4. The method of claim 1 in which the roll is moved longitudinally during the step of removing the mandrel from the roll.
5. The method of claim 1 including the step of pulling the mandrel longitudinally after the step of winding the web material around the mandrel.
6. The method of claim 5 in which the mandrel longitudinally elongates during the step of pulling the mandrel.
7. The method of claim 5 in which said mandrel has two ends and the step of pulling the mandrel is performed by pulling one end of the mandrel.
8. The method of claim 7 including the step of pushing the other end of the mandrel when said one end is pulled.
9. The method of claim 5 in which said mandrel has two ends and the step of pulling the mandrel is performed by pulling both ends of the mandrel.
10. The method of claim 5 in which the outer periphery of the roll is restrained from moving axially when the mandrel is pulled longitudinally.
11. The method of claim 5 including the step of applying adhesive longitudinally on the mandrel before winding the web material around the mandrel.
12. The method of claim 11 in which the mandrel is rotated relative to the roll during the step of pulling the mandrel longitudinally.
13. The method of claim 12 in which the step of rotating the mandrel relative to the roll smears the adhesive in a circumferential direction.
14. The method of claim 5 in which the mandrel is tubular and the step of pulling the mandrel longitudinally includes:
inserting a rigid shaft inside of the tubular mandrel;
moving a plurality of clamps which are spaced apart circumferentially around the outside of the mandrel radially inwardly to clamp portions of the mandrel against the rigid shaft; and
moving the clamps and the rigid shaft longitudinally to pull the mandrel longitudinally.
15. The method of claim 14 in which the step of moving the clamps radially inwardly to clamp portions of the mandrel against the shaft causes the mandrel to elastically deform into lobes between the clamps.
16. The method of claim 1 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% has a tensile yield strength divided by elastic modulus greater than 2.5%.
17. The method of claim 1 in which the longitudinal dimension of said material having a tensile yield strength divided by elastic modulus greater than 2.0% increases during the step of removing the mandrel from the roll.
18. The method of claim 1 in which the transverse dimension of said material having a tensile yield strength divided by elastic modulus greater than 2.0% decreases during the step of removing the mandrel from the roll.
19. The method of claim 1 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is flexible and elastic.
20. The method of claim 1 in which the mandrel is radially compliant.
21. The method of claim 1 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is thermoplastic.
22. The method of claim 1 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is HDPE.
23. The method of claim 1 in which the material of the mandrel is homogeneous.
24. The method of claim 1 including the step of recirculating the mandrel after the mandrel is removed from the roll of web material and using the mandrel to repeat steps a) and b).
25. The method of claim 1 including the step of applying adhesive longitudinally on the mandrel before winding the web material around the mandrel.
26. The method of claim 25 in which the mandrel is rotated relative to the roll during the step of winding the web material around the mandrel.
27. The method of claim 26 in which the step of rotating the mandrel relative to the roll smears the adhesive in a circumferential direction.
28. The method of claim 25 in which the mandrel is rotated relative to the roll before the step of removing the mandrel from the roll.
29. The method of claim 28 in which the step of rotating the mandrel relative to the roll smears the adhesive in a circumferential direction.
30. The method of claim 25 in which the mandrel is rotated relative to the roll during the step of removing the mandrel from the roll.
31. The method of claim 30 in which the step of rotating the mandrel relative to the roll smears the adhesive in a circumferential direction.
32. The method of claim 1 in which the mandrel is tubular and the step of removing the mandrel from the roll includes:
inserting a rigid shaft inside of the tubular mandrel; and
moving a plurality of clamps which are spaced apart circumferentially around the outside of the mandrel radially inwardly to clamp portions of the mandrel against the rigid shaft.
33. The method of claim 32 in which the step of moving the clamps radially inwardly to clamp portions of the mandrel against the shaft causes the mandrel to elastically deform into lobes between the clamps.
34. A method of forming a roll of convolutely wound web material comprising the steps of:
a) winding a web material around an elongated mandrel to form a roll of convolutely wound web material, the mandrel being comprised of material having a tensile yield strength divided by elastic modulus greater than 2.0%;
b) longitudinally elongating the mandrel; and
c) removing the mandrel from the roll.
35. The method of claim 34 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% has at least one of the following properties:
a) a glass transition temperature less than 60° F.;
b) a mass density (g/cc) less than 1.50;
c) a tensile elastic modulus less than 2,000,000 psi;
d) a tensile yield strength less than 50,000 psi;
e) a structure (% crystallinity) greater than 25;
f) a Poisson's ratio greater than 0.30.
36. The method of claim 34 in which the mandrel is moved longitudinally during the step of removing the mandrel from the roll.
37. The method of claim 34 in which the roll is moved longitudinally during the step of removing the mandrel from the roll.
38. The method of claim 34 including the step of pulling the mandrel longitudinally after the step of winding the web material around the mandrel.
39. The method of claim 38 in which the mandrel longitudinally elongates during the step of pulling the mandrel.
40. The method of claim 38 in which the outer periphery of the roll is restrained from moving axially when the mandrel is pulled longitudinally.
41. The method of claim 34 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% has a tensile yield strength divided by elastic modulus greater than 2.5%.
42. The method of claim 34 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is flexible and elastic.
43. The method of claim 34 in which the mandrel is radially compliant.
44. The method of claim 34 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is thermoplastic.
45. The method of claim 34 in which said material having a tensile yield strength divided by elastic modulus greater than 2.0% is HDPE.
46. The method of claim 34 in which the material of the mandrel is homogeneous.
47. The method of claim 34 including the step of recirculating the mandrel after the mandrel is removed from the roll of web material and using the mandrel to repeat steps a), b), and c).
48. The method of claim 34 in which the mandrel is substantially axially elastic.