Method and apparatus for producing coreless roll products
A method is provided for removing mandrels from successive rolls of convolutely wound web material. In one aspect, a roll of web convolutely wound around a mandrel is moved to a position in which the mandrel is aligned with a clasp with the clasp spaced apart from the mandrel. The clasp is then moved along a path toward the roll. Movement of the clasp toward the roll is stopped only when the clasp is in a position to engage the mandrel. The mandrel is engaged with the clasp. The clasp and the mandrel are moved away from the roll to withdraw the mandrel from the roll. The mandrel is released from the clasp when the mandrel is removed from the roll. The mandrel is removed from the path of the clasp. The steps are repeated for a subsequent roll.
1 . A method of removing mandrels from successive rolls of convolutely wound web material comprising the steps of:
a) moving a roll of web convolutely wound around a mandrel to a position in which a longitudinal center axis of the mandrel is aligned with a center axis of a clasp, wherein the clasp is spaced apart from the mandrel along a path parallel to the longitudinal center axis of the mandrel,
b) moving the clasp along the path parallel to the longitudinal center axis of the mandrel toward the roll from a puller stop position to a mandrel engagement position, the puller stop position being spaced away from the mandrel engagement position to allow the mandrel to be removed from the roll,
c) stopping the movement of the clasp toward the roll only when the clasp is in the mandrel engagement position to engage the mandrel,
d) engaging the mandrel with the clasp,
e) moving the clasp and the mandrel away from the roll along the path parallel to the longitudinal center axis of the mandrel to withdraw the mandrel from the roll,
f) releasing the mandrel from the clasp when the mandrel is removed from the roll,
g) removing the mandrel from the path of the clasp, and
h) repeating steps (a) through (g) for a subsequent roll.
2 . The method of claim 1 wherein the mandrel is comprised of a material having a tensile yield strength divided by elastic modulus greater than 2.0%.
3 . The method of claim 1 wherein the mandrel is at least one of substantially axially elastic, tubular, radially compliant, and homogeneous.
4 . The method of claim 1 wherein the step of moving the clasp along the path parallel to the longitudinal center axis of the mandrel toward the roll further comprises inserting a prong of the clasp into an end of the mandrel.
5 . The method of claim 4 wherein the step of engaging the end of the mandrel with the clasp further comprises clamping the mandrel between the prong and a plurality of clamping blocks of the clasp.
6 . The method of claim 1 wherein the step of moving the clasp and the mandrel away from the roll along the path parallel to the longitudinal center axis of the mandrel comprises moving the clasp with a first velocity and moving the clasp with a second velocity, wherein the first velocity is lower than the second velocity.
7 . The method of claim 6 wherein the step of moving the clasp and the mandrel away from the roll along the path parallel to the longitudinal center axis of the mandrel further comprises moving the clasp with a third velocity when the mandrel is removed from the roll, wherein the third velocity is lower than the second velocity.
8 . The method of claim 1 wherein the step of moving the clasp and the mandrel away from the roll along the path parallel to the longitudinal center axis of the mandrel further comprises rotating the mandrel during at least a portion of the step of moving the clasp and the mandrel away from the roll.
9 . The method of claim 1 wherein the step of moving the clasp and the mandrel away from the roll along the path parallel to the longitudinal center axis of the mandrel further comprises restraining the periphery of the roll from moving axially.
10 . The method of claim 1 in which each of the steps is performed on a group of at least two rolls with at least two mandrels.
11 . The method of claim 10 further comprising aligning the at least two rolls with at least two mandrels in the cross-direction before the step of moving the rolls to a position wherein the longitudinal center axis of each mandrel is aligned with the center axis of the respective clasp.
12 . The method of claim 10 wherein the step of moving the at least two rolls to the positions wherein the longitudinal center axis of each mandrel is aligned with the center axis of the respective clasp occurs simultaneously for each of the at least two rolls.
13 . The method of claim 1 in which the steps of moving the clasp and the mandrel away from the roll to withdraw the mandrel from the roll, and releasing the mandrel from the clasp when the mandrel has been removed from the roll, includes stopping the movement of the clasp away from the roll only when the mandrel has been withdrawn from the roll and the mandrel has been released from the clasp.