CA1281572C - Method of making a wound container - Google Patents

Abstract

METHOD OF MAKING A WOUND CONTAINER
ABSTRACT OF DISCLOSURE
Method of improving the effectiveness of the adhesive joining a first layer forming an inner lining of a wound container to the next adjacent layer comprising laterally spreading the web material forming the first layer while winding same under tension to substantially eliminate relative lateral movement between the liner layer and the next adjacent layer as the adhesive is being set and thereby improve the bonding.

Description

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FIELD OF THE INVENTION
The present invention is to an improved method of winding a multilayer container by laterally spreading the web material forming the inner lining layer as it is being wound.

BACKGROUND TO THE PRESENT INVENTION
The present invent;on is particularly applicable to the manufacture of cartons or the like as described in the United States Patent 4,441,948 issued April 10, 1984 to Gillard et al. As described in this patent a carton is formed by first winding an inner lining from material which preferably is paper known in the trade as liner (kraft paper) around a mandrel, after the lining has been wound part way around the mandrel a reinforcing layer (disclosed as single face, i.e. a corrugated medium lami-nated to a conventional liner paper) is applied to the mandrel and wrapped around the previously applied lining layer with the exposed convolutions of the corrugated medium contacting the exposed face of the lining layer.
Thereafter several layers of single face are wound onto the mandrel to form the multiwalled container. Adhesive is used to secure the tips of the corrugations to the pre-viously wound inner liner or the liner of the previously wound single face as the single face is wrapped around the mandrel.
Difficulties have been encountered obtaining a proper bond between the lining layer and the first layer of single face material. After extensive investigation by applicant it was determined that this poor adhesion was probably due to wrinkling of the liner as it was applied to the mandrel. An examination of the liner as it was being applied to the mandrel showed crepes or corrugations and in some cases creases with their axes extending longi-tudinally, i.e. in the direction in which the liner is 1'~8157'~

pulled onto the mandrel during the winding operation.
Applicant initially thought the formation ofthese corrugations was due solely to the longitudinal tension of the web as it was being wound. However exami-nation of the web when wound under low tension stillindicated an adhesion problem.
Examination of the roll of liner used to form the lining ply revealed that even before it was tensioned (still on the roll) the liner had longitudinal corruga-tions that could if not removed contribute to the problem.Variations in thickness profile of the liner were also a possible contributor to corrugation of the liner material.
It was theorized that the corrugations in the liner material did not flatten out during the winding op-eration and that the raised area (spaced from the surfaceof the mandrel) flattened as the first layer of single face was applied and this flattening caused relative move-ment between the inner lining layer and the first layer of single face as the adhesive was about to set or was in the process of setting thereby locally disrupting or weakening the bond.

BRIEF DESCRIPTION OF PRESENT INVENTION
It is an object of the present invention to provide a method of making a wound container wherein the adhesive bond between a sheet material forming the inner lining and the next adjacent layer forming the wall of the container is improved.
Broadly the present invention relates to a method of forming a multilayer container produced by wind-ing on a mandrel and composed of a inner lining layer and a plurality of superimposed structural layers wherein the inner lining layer is longitudinally fed to and its lead-ing edge held on the mandrel and is pulled under longitu-dinal tension onto the mandrel to wrap same therearound, ~8157~

then a web forming said structural layers is wound aroundlining layer on the mandrel and is adhesively secured to said lining layer, the improvement comprising continuously laterally spreading the said inner lining layer as it is being fed to said mandrel during the winding operation while maintaining the longitudinal tension in said lining layer substantially uniform across the width of said lining layer.
Preferably the lining material is laterally spread at substantially the same time as it is applied to the mandrel during the winding.
Preferably said lateral spreading comprises passing said lining layer in fric-tional contact with a surface of a spreader bar having alternative land and groove areas adapted to contact said l-ining at laterally spaced locations, said areas having side walls flaring laterally outward on each s-ide of the longitudinal center line of said lining toward the outside edge of said lining in the direction of travel of said lining layer over said spreader bar.

BRIEF DESCRIPTION OF THE DRAWING
Further features, objects and advantages will be evident from the following detail description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings in which:
Figure 1 is a schematic illustration of the ap-plication of a lining layer to a mandrel at the commence-ment of the lining operation.
Figure 2 is a side elevation similar to Figure 1 schematically illustrating the first step in the winding operation wherein the spreader bar is moved into position against the mandrel.
Figure 3 is a view along the line 3-3 of Figure 2 with the liner removed schematically illustrating the ~8~57'~

surface of the spreader bar.
Figure 4 is an end view of the spreader bar of Figure 3.
Figure 5 is a section through a wound container formed utilizing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates parts of winder operation described in the said U.S. Patent 4,441,948 but further includes a spreader bar 10 over which the lining material 12 which normally will be a kraft liner is passed while moving onto the rotatable mandrel 16. In the arrangement illustrated in the Figure 1 a suitable braking mechanism 18 including a back up roller 20 cooperating with friction shoe 22 applies drag on the lining 12 to ensure longitu-dinal tension in the lining 12 as it is being drawn onto the mandrel 16 as the mandrel rotates.
A pressure shoe 24 coopera-tes with the mandrel 16 and presses the lining 12 against the faces of the rec-tangular mandrel 16 as the mandrel is rotated as disclosedin said U.S. Patent 4l441,948.
As shown in Figure 2 the single face 26 is delivered via a conveyor 28 that inhibits relative move-ment between the single face 26 and conveyor 28 so that the single face 26 may be maintained under tension as it is wound on the mandrel.
As will be apparent the single facer 26 is composed of a liner as a flat sheet 30 with a corrugated medium 32 secured thereto.
30In operation an inner lining layer 12 is first applied at the mandrel 16 generally adjacent one of the corners of the mandrel as illustrated in Figure 2 and its leading edge is held on the mandrel by suitable means, e.g. retractable pins extending from the mandrel project-ing through the lining 12 adjacent to its leading edge.

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Lining 12 is usually fed from a continuous roll and is cut off into discrete sections of appropriate length via cut-off mechanism generally indicated 34.
When winding begins -the mandrel 16 rotates in the direction of the arrow 36 with the shoe 24 pressed there against and following the outer surface of the mandrel. The leading end of the lining 12 is, as above indicated held to the mandrel by a suitable means such as pins and the spreader bar 10 is moved from the position illustrated in the solid line in Figure 2 to the dotted line position where it is pressed towards the face of the mandrel 16 as it is ro-tated. The spreader bar 10 will be pressed toward the surface of the mandrel by a substan-tially constant preset total pressure as indicated by the double ended arrow 38 in Figure 2. Any suitable means may be used for maintaining the preset pressure. For example air pressure in cylinders urging the spreader bar 10 to the left of Figure 2 may be used provided these cylinders are connected to suff-iciently large air reservoirs so that change in volume by movement of the bar 10 to the left or right does not significantly change the pressure of the bar against the surface of the mandrel 16.
In operation the bar 10 applies the liner onto the mandrel and smooths the liner against the mandrel so that the lateral spreading of the liner material occurs substantially at the same time as it is applied to the mandrel, i.e. preferably there is no free draw between the spreader bar 10 and the mandrel 16.
Preferably a layer 9 of compressible (resilient foam) material will be interposed between the contacting surface or skin 11 of the bar 10 and the structural body of the bar 10 (Figure 4). This compressible layer 9 is compressed by the pressure of the bar squeezing the liner (and/or single face) against the mandrel so that an extended nip (about 2 to 5 inches (50 to 125 mm)) in the ~ ~ 8~ ~7'~

direction of lining 12 travel is formed. The skin 11 must be of flexible material such as a suitable flexible plastic that will deform to provide the extended nip the position and length of which changes relative to the structural body of bar 10.
It has also been found beneficial to crown the body of the bar 10 in the conventional manner so that when pressure is applied by the bar 10 it assumes a substanti-ally straight line configuration to match with the surface of the mandrel.
The surface of the skin 11 of the bar 10 is provided with a ribbed or contoured surface of alternating land and grooves as indicated by the numerals 40 and 38 respectively interconnected by substantially radially exiting walls that flare laterally outward in the direc-tion of movement of the lining 12 over the bar 10 on opposite sides of the longitudinal cen-ter line C-C of the web or lining 12 (Figure 3).
Preferably the angle of the flare of these walls connecting the land and groove areas gradually increases, it being smallest for the walls adjacent the center of the web and greatest the further spaced laterally outward from the center line C-C, i.e. the angular flare of the wall connectlng the land and groove area~ adjacent the center llne C-C is less than the angular flare of the walls con-necting the lands 40 and grooves 38 adjacent the outside edges of the web. This is illustrated in Figure 3 wherein the angles A of the walls closer to the longitudinal center line C-C are smaller than that angle 8 of walls spaced laterally towards the outside of the web or lining 12 or ends of the spreader bar 10.
In a specific embodiment of the present inven-tion a bar 10 with a length of wrap of the contact surface 11 by the lining 12 measured in the machine direction (longitudinal direction of the lining 12) of 6.25 inch ~ 81~7~

(150 mm) and adapted to accommodate a maximum liner width of about 90 inches (2285 mm) was used. This bar had land areas each with a uniform width measured in the cross-machine direction of about 1-1/2 inch (38 mm) spaced by 5 tapered grooves each having a width at its upstream end of about 1 inch (25 mm) expanding to a width of 1-1/2 inch (38 mm) at its downstream end and a uniform depth of about 0.06 inch (1.5 mm). These lands and grooves were symmet-rical on opposite sides of the center line C-C and were arranged so that each land extended the full length of the contact surface of the bar 10. The radial walls connecting the land and grooves closest to the center line C-C were spaced from the center line at the upstream end of the bar 10 by about 2 inch (50 mm) and at the downstream end of the bar 10 by 2-1/2 inch (56 mm). The wall closest to the center line C-C of each successive groove had its upstream and downstream ends spaced similarly from the upstream and downstream ends of the wall of immediately preceding groove so that the angle of the walls (connecting the 20 l ands and grooves) to the machine dlrection progressively increased as the positions of these walls progressed to-wards the ends of the bar 10 so that the walls connectlng the lands and grooves adjacent the ends of the bar lO had an angle of about 45 degrees to the machine direction, 25 i.e. angle B of Figure 3 was about 45 degrees.
Figure 5 shows a box or container 42 made using the present invention composed of four layers of single face 26 laminated to the inner lining 12 which is applied as a discrete sheet to the face of mandrel 16 and is glued to the first layer of single face. The single face is applied in overlying relationship to the liner on the mandrel 16. It has been found that when the spreader bar as above described was used the liner was well secured to the single face whereas when the bar 10 was not used defects were sometimes encountered.

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Having described the invention modifications will be evident to those skilled in the art without departing from the spirit of invention as defined in the appended claims. For example, the structural layers need not be wound from single face material, other suitable compressible material may be used.

Claims (4)

1. In a method in forming multi-walled containers by winding on a mandrel an inner lining layer followed by a plurality of structural layers and wherein the inner lining layer is held adjacent its leading edge on the mandrel and is fed longitudinally towards the mandrel as the mandrel is rotated thereby pulling the inner lining layer under longitudinal tension onto the mandrel and wrapping it there around, and wherein a web forming said structural layers is would around and adhesively secured to said lining layer, the improvement comprising, continuously laterally spreading said inner lining layer as it is being fed to said mandrel while maintaining longitudinal tension in said lining layer substantially uniformly across the width of said lining layer.

2. A method as defined in claim 1 wherein said lining layer is spread laterally substantially at the same time as it is applied to said mandrel during said winding operation.

3. A method as defined in claim 2 wherein said lateral spreading comprises passing said lining in frictional contact with a spreader bar having alternating land and groove areas adapted to contact said lining at laterally spaced locations, said land areas have side walls connecting same to said groove areas and when said side walls flare laterally outwards on opposite sides of the longitudinal centre line of said lining.

4. A method as defined in claim 3 further comprising pressing said bar toward said mandrel to form a nip with said mandrel and squeeze said lining and smooth same against said mandrel as said lining is applied to said mandrel.