US 3782663 A
An artificial surface capable of being rolled and unrolled is formed with flexible strips which prevent damage to the surface when said surface is unrolled over a supporting substrate.
Claims available in
Description (OCR text may contain errors)
United States Patent Stevenson 1 1 Jan. 1, 1974 [5 ARTIFICIAL ROLL-UP FIELD 2,845,976 8/1958 Miller 150 52 R 3,201,030 8/1965 Pollack [751 Invemo wflham Stevens, Rosevne 3,481,556 12/1969 McDonnell 242/86.52 2,826,523 3/1958 Blaszkowskij 150/52 R X  Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn. Primary Examiner-George F. Mautz Assistant Examiner-Edward J. McCarthy  Ffled' 1972 Attorney Alexander et a1.  App1.No.: 237,144
 US. Cl. 242/55, ISO/52 R, 161/21,
161/39, 161/62  ABSTRACT  Int. Cl B65h 19/02  Field of Search 242/55, 54 R, 86.52,
242/68, 684 76; 229/87 B 150/52 An artificial surface capable of being rolled and un- 7 39, 60 rolled is formed with flexible strips which prevent damage to the surface when said surface is unro11ed  References Cited over a supporting substrate.
UNITED STATES PATENTS 3,473,755 10/1969 Brown 242/86.52 6 Claims, 6 Drawing Figures ARTIFICIAL ROLL-UP FIELD BACKGROUND OF THE INVENTION The present invention relates to a large one-piece artificial surfacing suitable for covering and uncovering a base surface which may be rolled and unrolled without damage to it.
The construction of athletic stadiums or sports arenas suitable for numerous sports on a year-round basis is wide spread. Many of these are enclosed and are additionally designed for use as auditoriums and convention halls. In order to use these new arenas to best advantage, it is desirable that large one-piece artificial surfacings be placed on the permanent arena substrate, e.g., asphalt, when needed and conveniently rolled and stored when not in use. The artificial surfacings to be handled are large, being often 300-400 square yards and having widths of 50 yards and more, and highly susceptible to damage when being unrolled.
The use of a trailer for supporting and unrolling a strip of artificial turf (surfacing) from a roll has been suggested, e.g., US. Pat. No. 3,481,556. However, the system proposed is for laying or placing narrow strips of athletic turf, generally up to 14 feet wide. It is not designed for placing large, one-piece artificial surfacings, e.g., 100 feet wide by 300 feet long. Special problems arise in the unrolling of these huge wide rolls of artificial surfacing due to the danger during unrolling of pinching, or creasing, the surfacing and thereby tearing or deforming it.
GENERALDESCRIPTION OF INVENTION I have found that the difficulties inherent in attempting to unroll artificial surfacings of great width, e.g., 20 to 50 or more yards, and length, e.g., 20 to 200 yards or more, can be overcome by maintaining the artificial surfacing by convolutely rolling it on a core with the rolled product having included with each convolution for at least the larger convolutions of the rolled surfacing, at least one, and preferably more, flexible, nonstretchable normally flat strip. The inclusion of one or more such strips disposed to lie in the direction of movement of the roll as it unwinds prevents the roll from over-running itself while being unwound and thereby avoids the possibility of tearing or deforming the surfacing during unwinding. The strips may be simply laid out in parallel spaced relation to one another on the surfacing prior to rolling the surfacing on the core, or the strips may be a permanent, or temporary part of the surfacing itself.
The invention will be described in more detail in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view showing the loops formed when a conventionally wound, resilient, artificial playing surfacing is unrolled from a core.
FIG. 2 is a side elevational view of the roll of FIG. 1 showing the collapsed loop formed as the surfacing is unrolled.
FIG. 3 is a top view of a roll of artificial surfacing employing the present invention being wound on a core.
FIG. 4 is a side elevational view of the roll of artificial surfacing of FIG. 3 being unwound from its core.
FIG. 5 is an end view of an artificial surfacing having flexible strips embedded therein in accordance with this invention.
FIG. 6 is a perspective view of the surfacing of FIG. 5 wound on a core.
DESCRIPTION OF THE PREFERRED EMBODIMENT '13, 15 are formed because of the difference in the unwinding radius 14 and the loaded radius 16. This difference in the radii which causes a loop when unwinding resilient materials is well known in the art of roll winding. In thin materials such as paper or thin metal foils, the formation of the loop is not as pronounced as with thick resilient surfacings such as artificial playing fields and turfs. Also it is easier to devise methods for preventing the formation of loops in thin materials or where the weights handled are small, e.g., up to a few hundred pounds.
When the leading loop 13 reaches a sufficiently large size, the loop will collapse as shown in FIG. 2. The loop 13, now collapsed, provides a barrier which the trailing roll of material and its associated core 12 must pass over if unwinding is continued. This barrier would cause considerable resistance to further unrolling necessitating equipment many times larger than that necessary to unroll the field. Because of the large weights associated with artificial surfacings, in some cases up to tons, the surfacing is subject to damage by tearing, creasing, or deforming, e.g., stretching when the remaining roll of surfacing is rolled over the collapsed loop with further unwinding. The resulting damage may result in a surfacing unsuitable for use, e.g., athletic contests, and require time and expense to repair.
The present invention eliminates the problems noted with reference to FIGS. 1 and 2. Thus, in the form of the invention illustrated in FIGS. 3 and 4, thin, normally straight, flexible strips 16 of wood, plastic, metal or some combination of two or more of these materials, are laid lengthwise along the length of the surfacing 10 prior to winding the surfacing and the core 12 in forming a roll 17. As can be observed from FIG. 3, the strips 16 are laid on top of the surfacing 10 parallel to one another at spaced intervals across the width of the surfacing. This is done prior to winding the surfacing 10 on the core 12 with the strips extending for the major portion of the length of the surfacing. Preferably, each strip is a continuous piece, but a plurality of shorter length and laid more or less end-to-end to make the desired length. The surfacing 16 is then wound on the core 12 to form a roll 17 with the strips being interposed between the convolutions of the surfacing 10 on the roll 17.
Then, when the roll 17 is unwound by unrolling in the direction of the arrow as illustrated in FIG. 4, the loop 18 is prevented from curling under the roll by the presence of the stiffening strips 16.
In an alternative form of the invention as illustrated in FIG. 5, an artificial surfacing 19 made in accordance with the invention is shown. The surfacing comprises a resilient matrix 20 of synthetic or rubbery material having an artificial grass or the like 21 on the top surface thereof. Embedded within or otherwise attached to the undersurface thereof are strips 16. Again, these strips are parallel to one another and spaced across the width of the surfacing. However, in this form of the invention, the strips are a part of the surfacing itself and need not be removed when the surfacing is unwound from its roll and laid in place. The function of the strips is as described with reference to FIGS. 3 and 4.
FIG. 6 shows the surfacing of FIG. wound into roll form on a core 12.
There are several interrelated variables to be considered when making the storable core wound artificial surfacing rolls of this invention. The weight of the resilient artificial surface; the inherent strength of the resilient artificial surface; the physical properties of the flexible strips, e.g., yield strength, width, thickness, and the desired spacing between strips are all considered when designing an artificial surface which will not be subject to damage during unrolling.
The heavier the resilient surface used, the greater the number of strips or the stronger each strip must be to support the loop formed during unrolling. Among those materials suitable for supporting a loop while unrolling artificial surfaces are carbon spring steel, fiberglass, polyesters and fiberglass-polyester laminates. The presently preferred material is a 1095 carbon spring steel which combines flexibility with good yield strength.
The flexible strips may be placed parallel to the unrolling direction at varying separations depending upon the weight of the surface being unrolled and the strength of the flexible strips. For a heavy artificial surface, such as the Tartan Turf brand artificial turf of the Minnesota Mining and Manufacturing Co., which has a weight of about 1.8 lb./ft. and a thickness of up to about 34-inch, 3/32 inch thick spring steel strips placed on 10-12 foot centers will adequately support the loop formed during unrolling. A thinner material, e.g., l/l6 inch thick steel strip, is easier to handle, but
.a large number or wider strips would be necessary.
Where additional stiffness is desired, the flexible strips may be corrugated longitudinally to produce a stiffer material capable of supporting greater loads.
As noted hereinbefore, the flexible strips need not run the entire length of the surfacing since most artificial surfacing has sufficient inherent strength to support a loop of modest size while being unwound from a roll. Collapse of the loop becomes a problem only after a substantial amount of artificial surface has been unrolled, e.g., 50 feet or more, when the loops formed will be of substantial size. If desired, the flexible strips can be placed so as to be active only during the final portion of the unrolling procedure. Using strips which are only 2/3 the length of the field to be unrolled, the strips could be placed so as to be active only during the final 2/3 of the unrolling cycle.
The cross sectional configuration of the strip is not critical but flat strips are more easily placed on or embedded in an artificial surface.
The loop formed during unrolling is largest during the final revolution of the core and the physical properties necessary for the strips to support this loop can be readily determined for each surfacing from the diameter of the core, the weight per unit area of the surfacing and the maximum loop size.
What is claimed is:
l. A large, one-piece storable artificial surface suitable for covering a supporting substrate, said artificial surface capable of being rolled and unrolled without damage due to the collapse of loops formed during unrolling of the surface to cover said substrate comprising:
a resilient artificial surface;
a core about which said surface is convolutely rolled;
at least one flexible resilient strip convolutely interposed between convolutions of said surface said strip supporting and preventing the collapse of loops formed during unwinding of the roll thereby preventing the necessity of rolling said surface over a collapsed loop and damaging said artificial surface.
2. A large, one-piece storable artificial surface sutiable for covering a supporting substrate, said artificial surface capable of being rolled and unrolled without damage due to the collapse of loops formed during unrolling of the surface to cover said substrate comprising:
a resilient artificial surface;
a core about which said surface is convolutely rolled;
at least one flexible resilient strip imbedded in said surface said strip supporting and preventing the collapse of loops formed during unwinding of the roll thereby preventing said surface from rolling over a collapsed loop and the resulting damage to said artificial surface.
3. The storable artificial surfacing of claim 1 having a plurality of flexible strips.
4. The storable artificial surfacing of claim 3 where said strips are spring steel strips.
5. The storable artificial surface of claim 2 having a plurality of flexible strips.
6. The storable surface of claim 5 where said strips are flexible fiberglass-polyester laminate.