1. Field of the Invention
The invention has to do with sheet materials that are taken up on roll cores for storage and shipping. More specifically, the invention is an improvement in rolls of sheet vinyl floor covering and their method of manufacture which prevents damage to the layers of floor covering material that are first wound about the roll core.
2. The Related Art
Roll cores are commonly used to take up carpeting, sheets of vinyl floor covering and other sheet products as a part of the packaging process following manufacture of the carpet or sheet. For many years, manufacturers of roll cores have made a product with a flap attached to the core. The leading edge of the sheet product was placed under the flap to minimize or prevent damage to subsequent layers of the product. This system worked well when the packaging operation was done by hand. But with automation, it became very difficult to line up the flap with the leading edge of the sheet product.
Another solution was to make a thicker roll core and rout an inclined plane along its length. The maximum depth of the plane was sized to correspond with the thickness of the sheet and the leading edge of the sheet was abutted against the edge of maximum depth as the sheet was taken up on the roll. As with the foregoing design, this system worked better when the packaging operation was done by hand. Another drawback was that the maximum depth had to be varied to match the thickness of the sheet. This required a large inventory of rolls in facilities where sheets of varying thicknesses were made.
The present invention overcomes the foregoing problems by providing a solution that works well in automated systems and works well with sheet materials having different thicknesses.
In the manufacture of sheet materials such as sheet vinyl floor covering, the sheets are taken up on roll cores during the last stage of the manufacturing process. The floor covering is stored and shipped in the form of rolls.
When sheets of floor covering are wound onto a roll core, the leading edge along the width of the sheet creates a high pressure on the back of the next layer causing a sharp bend or crease in the layer which damages the product. Another problem occurs when the leading edge does not lie flat on the roll core, but instead is raised somewhat above the surface of the roll core. This raised leading edge also causes the next layer of floor covering wound over the leading edge to be bent and creased as shown in the end view of a roll of sheet vinyl floor covering illustrated in
We have discovered two solutions to this problem. Both solutions involve using a thin sheet of relatively stiff material, such as a paperboard or a heavy packaging paper. The relatively stiff material is disposed under tension between a leading edge of the floor covering and the lower surface of the next succeeding layer of floor covering. The tension keeps the leading edge flat against the outer surface of the roll core and prevents the leading edge from denting or creasing the next succeeding layer.
The first solution is illustrated in
The thicknesses in the drawing figures are exaggerated for illustrative purposes and it is important to note that the relatively stiff material 3 is thin as compared with the relatively thicker floor covering sheet material 1. As will be apparent to those skilled in the art, the relatively stiff material 3 must have sufficient strength to push the leading edge 2 down onto the outer surface of roll core 6 but it must be thin enough not to leave a mark or an indentation on the succeeding layer of sheet material 1 when the roll is unwound. The relatively stiff material 3 also must be strong enough not to tear under tension. In experimental work we successfully used as a relatively stiff material a packaging paper or hardboard having a thickness of about 15 mils. The floor covering had a thickness of about 80 mils.
As the winding continues, the floor covering sheet 1 is pulled onto the roll core 6. The first leading edge 2 and the adjacent portion of lower surface 8 is kept flat against the outer surface of roll core 6 by the relatively stiff material 3 and the rolling or winding tension. This is illustrated in
Thus, referring to
The thin sheet of relatively stiff material 3 or 3a has a second leading edge 5 or 5a and a second width about the same as the first width W. And the thin sheet of relatively stiff material 3 or 3a needs to be at least as wide as the print useable portion of sheet 1. The length of the thin sheet of relatively stiff material, referred to herein as the second length, is substantially less than the width. A second leading portion and a second trailing portion stp make up the length of the thin sheet of relatively stiff material 3. Referring to
The second lower surface 12 of the second leading portion of the thin sheet of relatively stiff material 3 is in direct contact with the outer surface of the cylindrical roll core 6. And the second lower surface 12 of the second leading portion of the thin sheet of relatively stiff material 3 is also in direct contact with the second leading edge 5 of the thin sheet of relatively stiff material 3 and the first leading edge 2 of the sheet material as illustrated in
The first embodiment has an additional advantage when the sheet 1 is floppy because the thin sheet of relatively stiff material 3 or 3a is adhered to the sheet 1 and it helps to feed the sheet 1 flat onto roll core 6 thereby preventing pleats in the sheet.
The second solution is illustrated in
Unlike the embodiment illustrated in
Thus, referring to
The thin sheet of relatively stiff material 7 has a second leading edge 9, and a second width about the same as the first width W. And the thin sheet of relatively stiff material 7 needs to be at least as wide as the print useable portion of sheet 1. The length of the thin sheet of relatively stiff material, referred to herein as the second length, is normally substantially less than the width. The thickness of the thin sheet of relatively stiff material 7, referred to herein as the second thickness, is substantially less than the thickness of the sheet material. And the thin sheet of relatively stiff material 7 must be thin enough not to leave a mark or indentation on the succeeding layer of sheet material 1 when the roll is unwound. The thin sheet of relatively stiff material 7 has a lower surface 11, also referred to herein as a second lower surface 11.
The first lower surface 8 of the first leading portion of the sheet material 1 is in direct contact with the outer surface of the cylindrical roll core 6. And the second lower surface 11 of the thin sheet of relatively stiff material 7 is in direct contact with the outer surface of the cylindrical roll core 6, the first leading edge 2 of the sheet material 1 and a portion of the upper surface 4 of the sheet material 1 as illustrated in
The sheet vinyl floor covering of the present invention has a thickness from about 40 to about 200 mils and a preferred thickness from about 50 to about 150 mils. In conventional manufacture, sheet vinyl floor covering has a width from about two to four meters or from about six feet to about twelve feet. The length taken up on one roll is from about 5 to about 40 meters or from about 17 to about 135 feet. The sheet vinyl floor covering is sufficiently flexible to be wound about a roll core.
The thin sheet of relatively stiff material used in the preferred embodiment is a heavy paper such as paperboard or packaging paper. It has a thickness from about 3 to about 20 mils, preferably form about 5 to about 14 mils, and sufficient strength under tension to press the leading edge of the sheet vinyl floor covering flat against the roll core outer surface without tearing. The thin sheet of relatively stiff material is sufficiently flexible to be wound about a roll core.
The ratio the thickness of the thin sheet of relatively stiff material to the thickness of the sheet material is from about 0.015 to about 0.5, preferably from about 0.033 to about 0.28.
In the first preferred embodiment of the invention, an adhesive is used to affix the second trailing portion of the thin sheet of relatively stiff material to the upper surface of the first leading portion of the sheet vinyl floor covering. This first leading portion extends across the width of the sheet vinyl floor covering and has a length sufficient to provide an adequate contact surface for good adhesion of the relatively stiff material to the sheet material, generally from about 8 to about 40 inches. Suitable non-staining adhesives for this application include acrylic hot melts and adhesive tapes such as double faced tapes having a width of two inches available from Tesa Tape, Inc., or Shanghai Hehe Hotmelt Adhesives Co., Ltd. Suitable acrylic hot melts are available from HB Fuller and Sailrite Enterprises, Inc.
The second leading portion of the relatively stiff material can optionally have an adhesive to adhere the relatively stiff material to the outer surface of the roll core. A contact non-staining adhesive such as hot melts can be used for this purpose. No adhesive is needed on the second leading portion, however, if it is long enough to be held against the roll core outer surface under tension by succeeding layers of material wound on the roll.
In the second preferred embodiment of the invention, it is not necessary to use an adhesive on the relatively stiff material because the tension of the sheet vinyl floor covering against the outer surface of the roll core will hold it in place. Of course, a contact adhesive can be used optionally to adhere the second leading edge of relatively stiff material to the outer surface of the roll core and/or the lower surface of the sheet vinyl floor covering.
While the invention has been described as it applies to sheet floor covering materials, the same principles can be applied by those skilled in the art to other sheet materials that are rolled up for storage, shipping or any other purpose.
This application claims the benefit of and priority to U.S. Provisional Application No. 61/432,642 filed Jan. 14, 2011 under the title IMPROVEMENT IN MANUFACTURE OF ROLLED SHEETS OF FLOOR COVERING. The content of the above patent application is hereby expressly incorporated by reference into the detailed description hereof.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CA2011/050735 | 11/25/2011 | WO | 00 | 6/6/2013 |
Publishing Document | Publishing Date | Country | Kind |
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WO2012/094729 | 7/19/2012 | WO | A |
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