Winding – tensioning – or guiding – Convolute winding of material – Simultaneous winding
Reexamination Certificate
1999-05-19
2001-05-22
Rivera, William A. (Department: 3653)
Winding, tensioning, or guiding
Convolute winding of material
Simultaneous winding
C242S541500, C242S541600, C242S547000
Reexamination Certificate
active
06234419
ABSTRACT:
TECHNICAL FIELD
The invention relates to a process for winding paper or cardboard webs onto winding tubes and a winding machine for implementing the process.
BACKGROUND OF THE INVENTION
There are known winding machines for the production of wound rolls from paper or cardboard webs, subdivided by longitudinal cutting into individual webs, wherein winding stations are arranged on both sides of a central support roller, each winding station consisting of two support elements, the individual webs being alternately supplied to them for winding. Each winding station holds a windup roll by means of guide heads rotatably supported on the support elements, which engage laterally into the respective windup tube. Thereby the guide heads bear the entire or partial weight of the roll, in order to keep line force at the contact line with the support roller, which is decisive for the winding quality, within a desired low range.
State of the Art
EP 0 481 029 B1 describes a winding machine wherein the total roll weight is borne by the guide heads. The windup rolls are laterally pressed against the support roller with the desired line force. In order to be able to additionally influence the winding hardness, particularly in the area with reduced diameter, the guide heads are provided with rotation drives.
From EP 0 629 172 B1 a winding machine with support rollers is known, wherein the winding stations are arranged on both sides next to an apex line of the support roller. At the beginning of the winding operation, the support roller bears the entire roll weight. When the roll weight starts to be too big for the desired line force starting from a certain windup roll diameter, the guide heads take over the ever increasing load portion of the roll weight.
The DE Utility Model 296 15 385 describes a roller for a winding machine with a hollow cylinder for a support body made of a solid material, on whose shell a deformable layer is applied, which consists of a cellular plastic material with a multitude of evenly distributed pores and which has a modulus of compression &kgr; of less than 10 MPa. It is indicated that such a roller can be advantageously used as support roller in a winding machine with support rollers, since it nearly eliminates a nip-induced expansion of the web.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a process by which windup rolls of the highest quality can be produced undisturbed from paper webs, even with specific sheet weights of less than 150 g/m
2
, at high production speeds exceeding 3000 m/min. A further object of the invention is to provide the winding machine for implementing the process of the invention.
SUMMARY OF THE INVENTION
The process of the invention for winding of paper or cardboard webs, particularly of paper webs of less than 150 g/m
2
, onto winding tubes, has the following features:
a) The windup rolls are pressed during winding with an adjustable contact pressure against a driven support roller, which has a volume-compressible outer layer with a thickness of at least 5 mm, preferably 15 mm to 30 mm, of a cellular plastic material with a multitude of evenly distributed pores and a modulus of compression &kgr; of less than 10 MPa,
b) the web fed to the windup roller wraps around the support roller upstream of the nip between the windup roll and the support roller in a region of the roller periphery,
c) depending on the construction of the outer layer the contact pressure of a windup roll against the support roller is selected so that a nip is formed which has in the direction of the roller periphery a measured width b of
at least 5 mm at a final production speed of more than 1000 m/min,
at least 15 mm at a final production speed of more than 2000 m/min,
at least 40 mm at a final production speed of more than 3000 m/min,
at least 70 mm at a final production speed of more than 4000 m/min, and
d) the web exiting the nip is subjected to a traction force of at least 1 N/cm of web width, preferably 3 to 10 N/cm of web width, by means of a central drive.
The winding machine comprises:
a longitudinal cutter for separating the web into individual webs,
a driven support roller wrapped by the web in the area of its roller periphery,
winding stations arranged on both sides of the support roller, each consisting of support elements movable transversely to the travel direction of the web, and for each support element a guide head, which can be introduced into the winding tube (
14
) and
an additional peripheral or central drive for driving the windup roll.
The support roller consists of a support body made of a solid material, on whose shell a deformable outer layer is applied, which comes in contact with the web and which consists of a cellular plastic material with a multitude of evenly distributed pores, open in the contact surface with the web (
1
), and which has a compression modulus &kgr; of less than 10 MPa, and which has a thickness of at least 5 mm, preferably 15 mm to 30 mm. Means are provided for selecting the contact pressure of a windup roll on the support roller in such a manner that a nip (
7
) is formed, which in the travel direction of the roller periphery has a measured width b of
at least 5 mm at a final production speed of more than 1000 m/min,
at least 15 mm at a final production speed of more than 2000 m/min,
at least 40 mm at a final production speed of at least 3000 m/min, and
at least 70 mm at a final production speed of at least 4000 m/min.
According to the invention, during winding the windup rolls are pressed with an adjustable contact pressure against a driven support roller partially wrapped by the web, which has an outer compressible layer made of a cellular plastic material with a multitude of evenly distributed pores and a compression module of less than 10 MPa. By means of an additional peripheral or central drive, the web exiting the nip between the support roller and the windup roll and winding on the windup roll is pulled with a traction force depending on the paper or cardboard type of at least 1 N/cm of web width. This prevents fold formation in the nip due to the difference between the web speed of the incoming web and the peripheral speed of the windup roll, which occurs as a result of the reduction of the effective radius of the support roller due to the compression of the outer layer in the nip. In order to compensate the speed difference, the web is pulled through the nip, which occurs without slippage due to the local deformation of the outer layer in the direction of the web travel.
The high production speeds are made possible by a destruction of the air boundary layer incoming on both web sides. With increasing speeds, the air boundary layer introduced into the nip during the winding of the web on the windup roll leads to problems in the winding buildup. The laminar air boundary layer is destroyed by the structured contact surface of the support roller by producing high-frequency vibration pressure peaks in the nip, which act through the web and cause turbulence in the air boundary layer on both sides of the web. The minimal width of the nip depending on the web speed insures that a sufficiently wide nip is created, wherein the boundary layer is destroyed.
The volume-compressible outer layer with a minimal thickness of 5 mm has the further advantage that it attenuates high-frequency vibrations, which stimulate the support roller from the outside, for instance vibrations triggered by windup rolls with profile variations. These vibrations are attenuated and not further transmitted to the support body, its bearing or the rest of the winding system, which results in a vibration-free winding operation.
The formation of the contact surface of the support roller at the web by means of the cellular plastic material has the further advantage that the friction coefficient between the support roller and the web remains unchanged, independently of the wear factor. In comparison to the coating with rubber, here the friction coefficient does not change because of the wear of the layer. A friction coefficient whic
Hehner Reinhard
M{overscore (u)}ller Georg
Peters Hans-Friedrich
Dubno Herbert
Jagenberg Papiertechnik GmbH
Rivera William A.
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