ATTACHMENT PLATE

Abstract

An attachment plate for securing a roof membrane to a roof deck includes a generally planar contact surface and at least one aperture for receiving a fastener for securing the plate to the deck with the membrane therebetween. An integrally formed, rolled collar surrounds the aperture to enhance the strength of the plate in the area adjacent the fastener. One or more stress relievers may also be formed at selected locations on the plate to provide sites for controlled deformation of the plate in the event extreme forces are exerted on the plate and the membrane, such as by heavy wind loads.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional Application No. 61/220,788 filed Jun. 26, 2009. The disclosure of which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to attachment plates for securing a membrane to a roof.

2. Background Art

Attachment plates have been used previously to attach membrane sheets to substrates such as a roof deck. The attachment plate is typically a generally planar sheet metal plate including one or more openings which accommodate a conventional fastener. The attachment plates are placed atop the membrane when the membrane is laid over the roof deck, and fasteners are inserted through openings in the plates, through the membrane, and into the roof deck to secure the plate and the membrane to the roof deck.

The attachment plates, which are typically circular in shape, are installed at the perimeter and corner areas of each of the sheets of the membrane utilized on a particular deck. Attachment sheets are also typically positioned at the seam of adjacent membrane sheets in a manner shown and described in U.S. Pat. No. 6,952,902, issued Oct. 11, 2005 to Richard Yaros, and hereby incorporated by reference. In particular, FIG. 6 of U.S. Pat. No. 6,952,902 illustrates, in cross section, the installation of an attachment plate at the seam of two membrane sheets, wherein one of the membrane sheets is secured by the attachment plate and the adjacent sheet overlaps the secured sheet, covers the attachment plate, and, typically, is sealed by a suitable adhesive on each side of the attachment plate along the seam of the overlapping, adjoining sheets.

It is desirable for the membranes to remain secured to the deck even when subjected to high winds under severe weather conditions. Under these conditions, the membrane may become partially separated from the roof deck and exposed to an uplifting force by extreme winds (e.g. greater than 75 miles per hour). It is desirable that the attachment plate remains secured to the deck, and retain the membrane in place without causing the membrane to tear at the contact locations between the membrane, the attachment plate, and the fastener as the membrane is pulled away from the roof deck by the uplifting wind.

It is, of course, also desirable to manufacture an attachment plate as economically as possible without compromising on the capability of the plate to retain the roof membrane in place under severe weather conditions.

SUMMARY OF THE INVENTION

The present invention provides an attachment plate for securing a roof membrane to a roof deck, the plate comprising a generally planar contact surface, at least one aperture for receiving a fastener for securing the plate to the deck with the membrane between the deck and the contact surface of the plate, and an integrally formed, rolled collar surrounding the aperture to enhance the strength of the plate in the area adjacent the fastener.

The attachment plate of the present invention may also include one or more stress relievers positioned at selected locations on the plate for providing a controlled deformation of the plate when it is subjected to extreme forces by the upwardly lifted membrane under severe wind conditions. These stress relievers may be formed as lanced or punched-through segments in the surface of the plate. The stress relievers allow the plate to deform in a controlled fashion when the roof membrane is subjected to a heavy wind load and thereby absorb the energy applied to the plate by the extreme forces exerted on the attachment plate and the membrane without tearing the plate or the membrane. A portion of the surface of the stress reliever will remain relatively undeformed when the plate is subjected to extreme forces. The leading edge of this relatively undeformed portion of the plate forms a gripping surface which may engage the roof membrane as it is stretched upwardly by wind forces and help restrain the membrane from further displacement and stretching.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of one embodiment of the attachment plate of the present invention;

FIG. 2 shows a side cross sectional view of the attachment plate shown in FIG. 1;

FIG. 3A shows an enlarged view of the formed hole including one embodiment of an integrally formed rolled collar;

FIG. 3B shows an enlarged view of the formed hole including another embodiment of an integrally formed rolled collar;

FIG. 4 shows an enlarged, schematic view of the through hole formed by the first punching step in the process of the present invention;

FIG. 5 shows an enlarged, schematic view of the through hole following the second forming step of the process of the present invention;

FIG. 6A shows a top view of the attachment plate of the present invention including stress relievers in an unstressed condition;

FIG. 6B shows an enlarged side cross sectional view of the integrally formed rolled collar for the stress plate of FIG. 6A;

FIG. 6C shows an enlarged side cross sectional view of one embodiment of a stress reliever;

FIG. 7A shows a top view of the attachment plate of FIG. 6A illustrating the stress relievers in a stressed condition;

FIG. 7B is an enlarged side cross sectional view of the integrally formed rolled collar of the stress plate of FIG. 7A;

FIG. 7C is an enlarged side cross sectional view of the stress reliever shown in a stressed condition;

FIG. 8 shows a side view of the attachment plate of the present invention installed in a roof deck in a normal unstressed condition;

FIG. 9 shows a side view of the attachment plate of the present invention being deformed by a roof membrane as it is separated from the roof deck by an extreme uplifting wind force;

FIG. 10A shows a top view of another embodiment of the attachment plate of the present invention including stress relievers in a stressed condition;

FIG. 10B shows an enlarged side cross sectional view of the integrally formed rolled collar for the stress plate of FIG. 10A; and

FIG. 10C shows an enlarged side cross sectional view of one embodiment of a stress reliever for the stress plate of FIG. 10A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-3A illustrate an attachment plate 10 which is one embodiment of the present invention. Attachment plate 10 includes a generally planar contact surface 12, an aperture 14, typically located at the center of the plate 10, for receiving a fastener for securing the plate atop a flexible membrane sheet on a roof deck, and an integrally formed, rolled collar 16 defining and surrounding the aperture 14 to provide an enlarged contact surface adjacent the shaft of the fastener when the attachment plate 10 is installed on a roof deck.

When installed using an appropriate fastener, such as a metal screw, the fastener, being mounted into the roof deck, exerts a downwardly clamping force on the attachment plate 10, urging the contacting surface 12 of the plate into contact with the roof membrane.

The integral rolled collar 16 provides a generally thicker contact surface (as best shown at 34 in FIGS. 3A and 3B) surrounding and abutting the fastener, thereby effectively increasing the shear strength of the plate when the plate is placed in a loaded condition caused by the membrane being lifted upwardly away from the roof deck by extreme wind forces. The rolled collar 16 thereby provides the same or even increased shear strength that was otherwise previously obtained in relatively thicker conventional attachment plates. Thus, the attachment plate 10 of the present invention can be fabricated from thinner sheet stock, thereby utilizing less material, but at the same time provide the same or increased shear strength and superior performance at a lower cost.

As illustrated in two different embodiments shown in FIGS. 3A and 3B, the rolled collar 16 may be fabricated in such a way that there is a space 30 between the lower contact surface 12 of the plate and the rolled upper surface 32 of the collar 16 thereby creating an inner wall 34 that has a height h and contact surface 54 greater than twice the thickness of the aluminum sheet. The shear force exerted by the shaft of the fastener on the plate when the membrane and plate are pulled as a result of extreme upward wind forces is thereby distributed over a larger surface, thereby reducing the likelihood that the attachment plate will rupture or tear along the inner wall of the aperture 14 when the plate is exposed to the extreme stress of such wind forces.

An aperture of about 0.47 inches is typically utilized for plates having two to three inch diameters. In the rolled collar illustrated in FIGS. 3A and 5, the collar 16 is formed with a space of about 0.010 to 0.070 inches, and the rolled over portion 32, 52 of the collar is typically about 0.06 inches. The collar is formed with suitable radii (shown as “r” in FIGS. 4-5) at the surface transition points to avoid sharp bends, and thereby provide a relatively stronger structure. In one embodiment, a radius of about 0.045-0.050 inches is formed at the transition points of the collar. For collars of the type shown in FIG. 3B the generally horizontal portion 26 of the rolled over material is typically about 0.3125 inches wide, and the generally vertical portion 28 of the collar is about 0.125 inches in length. Of course, as will be appreciated by those skilled in the art these various dimensions of the rolled collar may be varied, as dictated by the thickness and type of material utilized for the plate, as well as by the thickness of the membrane, size of the fastener, and other physical characteristics and performance standards for a particular roofing system application.

In this embodiment, plate 10 also includes first and second reinforcing ribs 18 and 20 comprising raised portions of the plate to further strengthen the plate 10. In the illustrated embodiment, the reinforcing ribs 18 and 20 are continuous and extend circumferentially around the plate between the center aperture 14 and the perimeter of the plate. However, it will be appreciated by those skilled in the art, that various numbers and patterns of ribs may be employed to provide structural reinforcement to the plate 10 without departing from the spirit of the present invention.

In the illustrated embodiment, the gripping plate 10 also includes a flange 22 which extends around the perimeter of the plate 10. The inboard portion of the flange 22 provides a portion of the generally planar contact surface 12 of the plate. The flange 22 may be angled slightly upwardly (when viewed in the side cross sectional view shown in FIG. 2) as the flange extends outwardly from the center of the plate, and may also include a scalloped edge (best viewed in the top view shown in FIG. 1) including a plurality of curved projections 24. The upwardly angled, scalloped edge configuration of the flange 22 provides a larger gripping surface in the event the membrane is pulled upward with respect to the roof deck and the attachment plate 10 and into contact with the inclined lower surface 26 of the flange 22 and the projections 24 at the edge of the plate.

The raised surface 26 of the flange 22 and the scallops 24 grip the membrane to limit sliding of the membrane as it is lifted away from the roof deck and the attachment plate by an extreme uplifting wind. In the embodiment shown in FIG. 1 twenty projections 24 are provided along the perimeter, with each projection having a depth of about 0.03 inches. Of course, it will be appreciated by those skilled in the art that various numbers of projections and depths may be employed to achieve a maximal contact surface with optimal gripping force, while minimizing the sharpness of the projections (thereby minimizing the possibility that the curved projections 24 on the edges of the flange cause a stretched, uplifted membrane to tear).

The upwardly projecting flange 22 typically extends at an angle, α of about 10-15° from horizontal. This slight elevation of the flange 22 ensures that the edge of the flange does not engage or pierce the membrane when the plate 10 is secured atop the membrane in normal installation, but still provides a gripping edge if the membrane is pulled upward away from the roof deck under severe wind loads, thereby tending to engage the uplifted membrane and prevent it from sliding or tearing under the extreme load.

In the illustrated embodiments, the attachment plate is generally round, with the aperture 14 located at the center of the plate. Each of the reinforcement ribs are also generally round in shape, since they typically, though not necessarily, extend continuously around the aperture at the center of the plate. However, as will be appreciated by those skilled in the art, other shapes, such as generally square, may be employed for the plate, and other orientations and configurations may be utilized for the reinforcement ribs, as desired.

The attachment plate of the present invention is preferably stamped from a formable sheet material using a high speed stamping press, such as straight side press Model No. 660, available from Bliss Manufacturing, of Hastings, Mich. Of course, other types of stamping presses may be utilized to facilitate the attachment plates. Continuous coil or sheet metals, such as galvanized aluminum, galvanized steel, stainless steel, or other resilient, malleable material may be used. In one embodiment “AZ50” galvanized aluminum is utilized. Thicknesses in the range of 0.022 inches to 0.039 inches (plus/minus 0.003 inches) have been found suitable for fabricating attachment plates for use in securing conventional membranes fabricated of polyvinyl chloride (or other suitable synthetic rubber materials). As described above, utilization of the integral, rolled collar 16 according to the present invention allows for plates fabricated from aluminum sheet of 0.022 inch thickness to perform a well as, or better than, prior conventional attachment plates having thicknesses of 0.038 inches or greater. Thus, attachment plate 10 of the present invention can be made stronger and/or more economically according to the present invention.

It will also be appreciated by those skilled in the art that attachment plate of the present invention may be made from other suitable resilient formable materials, such as plastic, or metal/plastic combinations, formed by other forming methods such as press molding, injection molding, extrusion, etc., without departing from the spirit of the present invention.

In the illustrated embodiments, the attachment plate is generally circular and in sizes having diameters of 2.375 or 2.625 inches. As previously described, other sizes and shapes (such as rectangular, round, oval, etc.) may be employed, depending upon the type, thicknesses, and weight of the membrane, the type of roof deck, and other stress load conditions anticipated at a particular installation.

The reinforcing ribs in the illustrated embodiments are preferably generally arcuate in shape in cross section, with the rib extending about 0.05 inches above the contact surface of the plate. Of course, reinforcing ribs having varying heights above the contact surface of the plate, and with other cross-sectional shapes may be employed so long as the ribs provide suitable strength and rigidity to the plate.

Referring now to FIGS. 4 and 5, the integral rolled collar 16 may be formed in a sequential stamping process. In the initial step, shown in FIG. 4, the aperture 14 is created by a punching process utilizing a punch tool which in a single operation punches a hole in the plate and thereafter extruded material from the major surface of the plate surrounding the punched hole into a generally vertically extending cylinder 42 extending from the major surface 44 of the plate. In one process of forming the collar, 16, a second forming die is then pressed into contact with the plate with sufficient force to form the upper portions of the cylinder 42 into the desired collar shape, such as the shapes shown in FIGS. 3A and 3B. Again, as previously described, the transitions in the collar are preferably formed with a suitable radius, r, so as to avoid sharp transition points which might weaken the collar.

As shown in FIG. 5, the displaced material 42 may be formed in such a manner that the rolled over material 52 extends outwardly from the aperture and generally parallel to the major surface 44, of the plate 10, but in a spaced apart relationship to the major surface 44 thereby creating a space 50 between the rolled over upper surface 52 and the major surface 44 of the plate. It will be appreciated that the inner wall 54 of the collar will have a height equal to at least twice the thickness of the plate, plus the height of the space 50 between the upper surface 52 and major surface 44. Thus, the height of the inner wall 54 and, therefore, the surface area brought into contact with the shank of the fastener in a loaded condition, may be effectively increased by increasing the space 50 between the top portion 52 of the rolled over wall and the major surface 44 of the plate. As earlier described, by employing an integral rolled collar in this manner, the attachment plate 10 may be formed of relatively thinner sheet stock than previously utilized in similar attachment plates while maintaining, or increasing, the shear strength of the plate at the stress point of the abutment of the fastener shank with the aperture of the plate, thereby improving the performance of the attachment plate under high load conditions. Alternatively, the integral rolled collar may be utilized on plates of conventional thickness to improve the strength and performance without adding material to the plates.

FIG. 8 illustrates, in side cross-sectional view, an attachment plate 10 according to the present invention installed atop a first membrane sheet 82. A threaded fastener 84 extends through the aperture 14 in the plate, pierces membrane 82, and pierces the roof deck 86 (as well as any optional layer(s) of insulation placed therebetween), securing the first membrane sheet 82 between the attachment plate 10 and the roof deck. A second membrane (not shown) may be glued, sewn or otherwise secured to the first membrane at 88, and laid over one or more attachment plates at the edge of the first membrane 82, thereby defining a seam between the two roof membranes.

Referring now to FIGS. 6A-6C and 7A-7C, in another embodiment of the present invention, an attachment plate 60 is provided with an aperture 14 for receiving a fastener, and an integral formed collar 16, as described above, for increased shear strength in retaining the plate in place relative to the fastener when the plate is under extreme load, and a series of stress relievers 66 formed at selected locations around the perimeter of the plate to provide pre-defined deformation sites on the plate 60. These stress relievers may be lanced, or completely punched-through areas of the plate 60 which provide weakened sites that will allow for greater deformation of the plate at selected locations when the plate is subjected to extreme forces by a moving membrane that is separated from the roof deck and is being pulled upward by high winds. As shown in FIGS. 7A-7C and 9, this controlled deformation of the plate serves to absorb energy transmitted as a result of these extreme forces, rather than transmit the energy directly to the site of the attachment of the plate at the aperture 14, thereby reducing the stress on the plate caused by the force of the relatively static threaded fastener on the plate that is being strained out of position by the extreme wind forces. As a result, in an extreme wind condition such as a hurricane, an attachment plate configured with stress relievers 66 is more likely to absorb the extreme wind forces without failing completely (e.g. shearing completely off as a result of the force of the fastener on the wall of the plate at the aperture 14, or tearing out of the fastener from the roof deck) thereby keeping the membrane generally attached to the roof deck under extreme conditions.

In particular, FIGS. 7A and 7C depict the stress relievers in a deformed state wherein an outer portion 70 of the plate 60 has been deformed upwardly as a result of stress of the lower surface of the plate 60 by the roof membrane 82 being pulled upwardly by an extreme force, such as high winds. This controlled deformation of a portion 70 of the plate allows for a controlled transmission and absorption of the energy applied by the upwardly stretched, wind-blown membrane 82, thereby lessening the stress on the remaining central portion 72 of the plate, as well as the collar 16, and the fastener 84. In addition, upon deformation of the outer portion 70 of the plate under stress, the adjacent, undeformed portion of the plate forms a gripping surface 76 which may engage the roof membrane 82 as it is pulled upward by wind forces and help restrain the membrane 82 from further displacement and stretching in the vicinity of the central portion 72 of the attachment plate 60. The gripping surface 76 has a generally smooth, arcuate shape in the illustrated embodiments. Alternatively, the stress reliever can be formed such that the gripping surface 76 is scalloped in a manner similar to the outer edge of the raised surface 26 to thereby provide a larger gripping surface at the undeformed portion 76 of the stress reliever in the event the attachment plate 60 is deformed by an extreme load and the gripping surface 76 moves into contact with the membrane.

Referring now to FIGS. 10A-10C, in another embodiment of the present invention, an attachment plate 90 may include a plurality of stress relievers 92, each of which are lanced in a shape which includes a generally arcuate surface extending at the radially outward edge 94 of the stress reliever 92, and first and second generally linear side surfaces 96 and 98. In the attachment plate illustrated in FIG. 10A, the outward edge 94 is scalloped to include a plurality of projections 95. As shown in FIG. 10C, this stress relievers 92 may be formed to project downward from the surface of the plate 90 when the plate is in the unstressed condition.

In one embodiment, the stress reliever 92 is formed part to project downward at an angle sufficient that the leading-edge 94 of the stress plate engages the membrane when the attachment plate 90 is installed on the roof deck in its unstressed condition. In this embodiment, the contact of the leading edges 94 of the stress relievers 92 with the membrane provide an additional gripping force, supplementing the gripping force provided by the contacting surface of the flange 22. In one embodiment, the stress relievers 92 are formed to project downward at an angle sufficient that the stress relievers 92 and engage and compress the membrane such that the stress relievers 92 provide the primary gripping force for the plate 90.

The illustrated embodiments depict three stress relievers, each having a generally arcuate shape. In the illustrated embodiments, the stress relievers are equal in length, and are spaced at equal distances apart from each other about the circumference of the plate, with the space between the stress relievers being equal or greater in length than the length of an individual stress reliever. Of course, however, the number, shape, length, and placement of the stress relievers may be varied to achieve desired performance characteristics for a particular roofing system and environment.

It will be appreciated that the shape and position of the portions of the plate 70 and 76 immediately adjacent stress reliever 66 are slightly exaggerated in FIGS. 6-9 for the sake of illustration. As will be appreciated by those skilled in the art the lanced or punched through areas defining the stress relievers 66 may be barely detectable when the plate is in an unstressed condition. Similarly, deformation may occur at some, but not all, of the stress reliever locations depending on the degree and direction of the force exerted on the attachment plate by a wind-blown, uplifted membrane.

Each of the disclosed embodiments of the present invention provide an attachment plate which is simple to fabricate, yet strong, lightweight, and effective to provide attachment of a roof membrane, while substantially reducing or eliminating membrane tear problems experienced when using previous attachment plate designs.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.

Claims

1. A plate for attaching a roof membrane to a roof deck, the plate comprising: a generally planar contact surface including at least one aperture for receiving a fastener for securing the plate to a roof deck with the membrane between the deck and the contact surface of the plate and an integrally formed, rolled collar surrounding the aperture to enhance the strength of the plate in the area adjacent the fastener.

2. The attachment plate of claim 1 wherein the rolled collar includes a generally vertical inner wall and a generally horizontal upper surface, and wherein the inner wall has a height at least twice the thickness of the plate.

3. The attachment plate of claim 1 wherein the rolled collar includes a generally vertical inner wall and a generally horizontal upper surface, and wherein the inner wall has a height greater than twice the thickness of the plate.

4. The attachment plate of claim 1 further including at least one stress reliever positioned at a selected location on the plate for providing a controlled deformation of the plate when it is subjected to extreme forces by the upwardly lifted membrane under severe wind conditions.

5. The attachment plate of claim 4 wherein at least one stress reliever is formed as a lanced segment in the surface of the plate.

6. The attachment plate of claim 4 wherein at least one stress reliever is formed as a punched-through segment in the surface of the plate.

7. The attachment plate of claim 1 wherein the plate includes one aperture located at the plate, and further including at least one reinforcing rib, each comprising a raised portion of the plate to further strengthen the plate.

8. The attachment plate of claim 7 wherein the first and second reinforcing ribs are each continuous and extend circumferentially around the plate between the center aperture and the perimeter of the plate.

9. The attachment plate of claim 1 further including a flange extending around the perimeter of the plate, and wherein the inboard portion of the flange provides a portion of the generally planar contact surface of the plate.

10. The attachment plate of claim 9 wherein the flange is angled slightly upwardly as the flange extends outwardly from the center of the plate.

11. The attachment plate of claim 9 wherein the flange includes a scalloped edge.

12. A plate for attaching a roof membrane to a roof deck, the plate comprising: a generally planar contact surface including at least one aperture for receiving a fastener for securing the plate to a roof deck with the membrane between the deck and the contact surface of the plate and at least one stress reliever positioned at a selected location on the plate for providing a controlled deformation of the plate when it is subjected to extreme forces by the upwardly lifted membrane under severe wind conditions.

13. The attachment plate of claim 12 wherein at least one stress reliever is formed as a lanced segment in the surface of the plate.

14. The attachment plate of claim 12 wherein at least one stress reliever is formed as a punched-through segment in the surface of the plate.

15. The attachment plate of claim 12 wherein at least one stress reliever is formed in a shape such that, upon deformation of the outer portion of the plate under stress, the adjacent, undeformed portion of the plate forms a gripping surface which may engage the roof membrane as it is pulled upward by wind forces and help restrain the membrane from further displacement and stretching in the vicinity of the central portion of the attachment plate.

16. The attachment plate of claim 15 wherein at least one stress reliever is formed such that the gripping surface is scalloped, thereby providing a larger gripping surface at the undeformed portion of the stress reliever in the event the attachment plate is deformed by an extreme load and the gripping surface contacts the membrane.

17. The attachment plate of claim 12 wherein each stress reliever is formed in a shape including a generally arcuate surface extending at the radially outward edge of the stress reliever, and first and second generally linear side surfaces extending generally in the radial direction, wherein the arcuate surface is scalloped, and wherein each stress reliever is formed to project downward from the plate towards the membrane when the plate is secured to the roof deck.

18. The attachment plate of claim 17 wherein the radially outward edge of each stress reliever projects downward into contact with the membrane when the plate is secured to the roof deck.

19. The attachment plate of claim 12 further including an integrally formed, rolled collar surrounding the aperture to enhance the strength of the plate in the area adjacent the fastener.

20. A plate for attaching a roof membrane to a roof deck, the plate comprising:

a generally planar contact surface including at least one aperture for receiving a fastener for securing the plate to a roof deck with the membrane between the deck and the contact surface of the plate;

an integrally formed, rolled collar surrounding the aperture to enhance the strength of the plate in the area adjacent the fastener;

at least one stress reliever positioned at a selected location on the plate for providing a controlled deformation of the plate when it is subjected to extreme forces by the upwardly lifted membrane under severe wind conditions; and

a flange extending around the perimeter of the plate, the inboard portion of the flange providing a portion of the generally planar contact surface, wherein the flange is angled slightly upwardly as the flange extends radially outward from the center of the plate, and wherein the flange includes a scalloped edge including a plurality of curved projections.