Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With bending – folding – winding – or wrapping means
Reexamination Certificate
1999-09-14
2001-11-06
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
With bending, folding, winding, or wrapping means
C156S210000
Reexamination Certificate
active
06311754
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention pertains to an apparatus for forming a single face web of corrugated paperboard and, more particularly, to a corrugating roll assembly for a single facer.
In the manufacture of corrugated paperboard, a single facer apparatus is used to corrugate the medium web, apply glue to the flute tips on one face thereof, and to bring a liner web into contact with the glued flute tips of the medium web with the application of sufficient heat and pressure to provide an initial bond. A conventional single facer typically includes a pair of fluted corrugating rolls and a pressure roll, which are aligned so the axes of all three rolls are generally coplanar. The medium web is fed between the inter-engaging corrugating rolls and the adhesive is applied to the flute tips by a glue roll while the medium is still on the corrugating roll which comprises the intermediate of the three roll arrangement. The liner web is immediately thereafter brought into contact with the adhesive-coated flute tips in the nip between the pressure roll and the corrugating roll.
As corrugating nip roll pressures and corrugating speeds have increased, changes have been made in the construction of single facers to maintain the quality of the corrugated medium and to attempt to deal with the problems of high noise and vibration. For example, the load between corrugating rolls at the corrugating nip has required that one of the fluted corrugating rolls be made with a crowned surface to accommodate roll deflection under high nip loads. Deflection as a result of high loading is also believed to be one source of noise and vibration. In a conventional single facer construction, where the two corrugating rolls and the lower pressure roll are in general alignment (their axes lying generally coplanar), corrugating roll loads are transmitted to the pressure roll adding further to the problems associated with high loads and high speeds. This has resulted, in some cases, in manufacturing the pressure roll with a negative crown to match deflections in the corrugating roll which together form the nip for joining the two single face web components.
One of the most serious problems in the operation of high speed single facers is the so-called “labyrinths” effect. In order to handle high loads and higher speeds, single facer manufacturers have gone to increasingly larger diameter, heavier and stronger corrugating rolls. As the medium web is drawn into the pressure nip, formed by the inter-engaging flutes on the two corrugating rolls, the medium web begins to be deformed, folded and gathered as it moves into the actual nip centerline where full engagement of the flutes occurs. Larger diameter corrugating rolls inherently create a more tortuous path for the web as the web begins to be wrapped partially around opposite alternating teeth or flutes of the mating corrugating rolls while moving into the fully nipped position. Each wrap of the web encompasses a slightly larger radius around the flute tip as it approaches the nip and each deformation or wrapping of the web on a flute tip adds a tension component to the overall web tension. As indicated, the additive labyrinth effect is increased as the corrugating roll diameters increase and it is not uncommon for the medium web to rupture or tear.
One proposed solution to the labyrinth problem is disclosed in U.S. Pat. No. 3,990,935. The single facer construction disclosed in this patent proposes to maintain relatively small diameter corrugating rolls to minimize the labyrinth length and to provide internally pressurized flexure compensation for the inevitable bowing to which the rolls are subjected under high corrugating nip loads. Another proposed solution to the labyrinth effect is described in U.S. Pat. No. 4,531,996. In accordance with this patent, the upper corrugating roll contact with the lower corrugating roll is “dephased” by dividing the upper roll into axially adjacent segments each of which makes nip contact with the other corrugating roll at a different point. Alternately, the dephasing effect is provided by making the segments of the upper corrugating roll of different diameters. Both of the foregoing solutions require extremely complex roll constructions. Alternately, one of the larger diameter corrugating rolls may be eliminated and other means used to stabilize a small diameter intermediate corrugating roll to provide the required nip force and prevent deflection of the small roll.
SUMMARY OF THE INVENTION
In accordance with the present invention, the labyrinth effect is minimized in a modified single facer by utilizing a small diameter corrugating roll and a larger diameter conventional corrugating roll and capturing the small diameter roll in a manner to balance the loadings and minimize roll deflection.
In accordance with one embodiment, a single facer utilizes a pair of conventional fluted main corrugating rolls mounted and operated to impose a corrugating nip force acting normal to the roll axes and generally in the plane common thereto. An intermediate fluted corrugating roll is mounted between and in rotatable engagement with both main corrugating rolls and with its axis lying generally in the same common plane. The intermediate roll forms the corrugating nip with one of the main corrugating rolls and has a diameter, as compared to the main corrugating rolls, sufficiently small to provide a reduction in the labyrinth paper path sufficient to prevent rupture of the medium web. By capturing the intermediate web corrugating roll between the two main corrugating rolls, the nip force acts to hold the smaller intermediate roll against axial bending in the common plane of their axes.
A significant reduction in the labyrinth path of the web is effected by maintaining the ratio of the diameter of the main corrugating roll and the intermediate corrugating roll which together form the nip not less than about 3:1. Preferably, one or both of the main corrugating rolls are heated and the intermediate corrugating roll may be heated as well.
The apparatus may be constructed to wrap the corrugated medium on the intermediate corrugating roll downstream of the corrugating nip to the line of engagement between the intermediate roll and the other main corrugating roll, and then back wrapped on the other main corrugating roll downstream to the point of joinder with the liner web in the pressure nip. Preferably, the intermediate corrugating roll and the other or lower corrugating roll include means for applying a vacuum to the portions of the corrugated medium wrapped thereon. The apparatus may include a pressure roll of any common construction mounted in operative rotational contact with the main corrugating roll carrying the corrugated medium. The pressure roll carries a liner web and forms with the main corrugating roll a pressure nip to join the liner web to the corrugated medium to the flute tips of which a suitable adhesive has been applied.
In a presently preferred embodiment of the single facer of the subject invention, only one large diameter fluted corrugating roll is utilized. The small diameter fluted corrugating roll, preferably having a diameter not greater than about one-third the diameter of the large corrugating roll, is positioned to interengage the large roll to create therewith a corrugating nip. In place of the other large diameter corrugating roll of the previously described embodiment, means are provided for applying a radial force to the small diameter roll generally along the axial length thereof with the resultant of the radial force creating a nip force which acts through the corrugating nip in a plane generally common to the axes of the corrugating rolls. The radial backing force also acts to restrain the small diameter roll against deflection in a manner similar to the upper of the two large corrugating rolls in the previous embodiment.
Preferably, the force applying means comprises an idler roll means which rotatably engages to small diameter corrugating roll. The idler roll means may comprise a resilient roll or
Andrus Sceales, Starke & Sawall
Ball Michael W.
Marquip, LLC
Piazza Gladys
LandOfFree
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