WO2010005556A1

WO2010005556A1 - Air leader system

Info

Publication number: WO2010005556A1
Application number: PCT/US2009/003976
Authority: WO
Inventors: Laurie Taylor
Original assignee: Laurie Taylor
Priority date: 2008-07-07
Filing date: 2009-07-07
Publication date: 2010-01-14

Abstract

The present invention is a system for data rooms or other environments containing heat generating equipment, the system comprising at least one panel for restricting airflow relative to electronic enclosures for heat generating electronic equipment, and facilitating air moving toward units for cooling hot air.

Description

AIR LEADER SYSTEM

PRIORITY CLAIM

This application claims priority to co-pending U.S. Provisional Patent Application No. 61/078,729, filed July 7, 2008, the entirety of which is hereby incorporated by reference.

BACKGROUND

Equipment and data centers have thermal cooling requirements in order for proper equipment function and longevity. A large amount of electricity is usually required for equipment in these centers, and even more energy is required to cool them. The equipment used in these centers typically uptake cool air from the front of electronic enclosures, such as server racks, and fans blow the hot air out the back of the electronic enclosures. The arrangement of the electronic enclosures typically involves rows of enclosures, where the front of a row of enclosures faces the front of another row of enclosures. The same can be said for the backs of the enclosures; they are positioned in such a way that the backs of the rows of enclosures are facing each other. This placement of the equipment effectively defines what are known as hot aisles and cold aisles. The hot aisles and cold aisles are typically alternating in data and equipment centers.

Equipment and data centers are usually cooled using a plenum or underfloor air distribution (UFAD). The plenum is typically the space for delivering cold air from a variety of sources, individually or in conjunction with one another, such as cold room air conditioners (CRAC), through ductwork to heating, ventilating and air conditioning (HVAC) units, or through the use of air handling units (AHU). Arranging equipment into hot aisles and cold aisles helps to reduce the recirculation of hot air exhausted from equipment from re-entering the equipment where cold air intake should occur. The reduction in hot air intake into the equipment helps to keep equipment cooler, thereby preventing overheating and damage to the equipment that occurs as a result of improper cooling. Pumping cold air into the cold aisles where the equipment enclosures intake the air and exhaust hot air from the back of the equipment to the CRAC or other cooling units increases efficiency. However, the efficiency at maintaining a separation between hot and cold aisles is undercut by the space surrounding the aisles from overhead and between the electronic enclosures allowing air currents to both passively and actively crossover from the hot aisle into an adjacent cold aisle or vice versa.

A method or system for reducing this crossover of air between the aisles could increase the efficiency for maintaining equipment temperatures and thereby reduce facility costs. Two common methods are now identified to prevent the crossover of air between the aisles: draping plastic sheeting over equipment enclosures, and rigidly affixing plastic to the electronic enclosures to reduce airflow. There are drawbacks to both of these methods.

Plastic sheeting, while removable and capable of reducing airflow, it is aesthetically unappealing, can sag, and may create potential dangers to personnel. Much of the commercially available plastic sheeting is not available as a fire-rated material suitable for use in data rooms or data centers, or to withstand the potential heat that can be generated by the electronic equipment. In addition, because the draping of sheets of plastic is not fixed and can sag, there is potential that the material can fall and cover the electronic equipment. The plastic would then cover areas on the equipment that would otherwise be taking in cold air or come into contact with the hot aisle side where temperatures can become very high. In both situations either the proximity to the high heat or the blocking of cold air intake, can result in a potential fire hazard or equipment failure. Plastic sheeting thus does not serve as a reasonable choice for solving the problem of crossover between hot aisle air and cold aisle air.

The use of rigid material, such as Plexiglass, has similar drawbacks. Data centers are regularly re-configured to accommodate the needs of business. Because such material is rigidly mounted to the electronic enclosure, changing the location of equipment can become more difficult. The installation of the material requires tools for cutting, shaping and installation, as well as removal. The installation and material add unnecessary cost to the construction and cause damage to the existing electronic enclosures. In addition, the installation of a rigid material can block the efforts of fire suppression. The use of rigid material or plastic to reduce crossover airflow can be a safety hazard, lacks the desired efficiency, and can inhibit the data center adaptability.

An objective of the present invention is to provide a simplified panel assembly in which individual panels can be easily modified to fit the intended area of installation.

SUMMARY OF THE INVENTION

The present invention relates to a panel and system for data rooms or other environments containing heat generating equipment. More particularly, the invention pertains to panels and systems for restricting airflow relative to electronic enclosures for heat generating electronic equipment and facilitates air moving toward units for cooling hot air. Also, the invention pertains to an assembly of at least one or more panels positioned to reduce the crossover of airflow between aisles of electronic enclosures from hot aisles into cold aisles and to direct the flow of air toward a cooling unit for conditioning the room air. The present invention includes a leader system for at least partially preventing airflow from the back of the equipment enclosures (the hot air) toward the front of the equipment enclosures (the cool air). The present invention seeks to achieve this result in a manner that is substantially nondestructive to electronic enclosures and building structures, yet also remains adaptable to accommodate the needs of ever-changing equipment and data centers.

Preferably the leader system includes a minimum of materials, and is preferably made substantially of fire resistant material. The fire resistant material is in the form of sheets or panels that have been scored to enable installation by breaking apart or cutting the material. The material is separable so as to be shaped and modified to fill the spaces located above and between electronic enclosures to reduce the crossover of air between the hot and cold aisles, thereby creating a leader system for air flow from the backs of electronic enclosures to air handlers for cooling.

In accordance with other aspects of the present invention, a need to reduce crossover from hot to cold aisles above the electronic enclosures requires the leader system to fill the space above the enclosures. In order to achieve a reduction in crossover air, minimize the costs and the number of different components of the leader system, a more rigid structure is needed to enable large pieces of the material to be suspended, mounted, or erected. The addition of support to the paneling can be achieved by a variety of methods. In one embodiment, improved support of the paneling may be achieved by adding additional elements, such as a plastic bracket that may be snapped onto the top edge of the paneling. The plastic bracket may be removably affixed to the material, and further may be such that an additional rigid support structure, such as an aluminum casing, may be attached to the plastic bracket. Eyelets can be attached to either the plastic bracket alone, or to the plastic bracket with plastic casing or to the aluminum casing. The eyelets may permit the attachment to a hanger rod. The hanger rod should be sufficiently strong enough to hold the weight of the suspended panels and all supporting material. In addition it is preferably also be somewhat flexible, so as to be able to slightly move with the drafts and airflow within a data center. The hanger rod is preferably a wire rod that has been bent on both ends to form hooks, though it may be of any suitable shape and made of any suitable material. The hooks preferably attach to the paneling by way of the eyelet and to the ceiling by wire clip or carabiner, grid hanger rod or other suitable mounting device. The materials used preferably have the capacity to withstand high temperatures exhausted from the electronic equipment in the range of at least about 128-140 degrees Fahrenheit.

In another embodiment of the present invention the additional structural integrity for suspending, mounting or otherwise installing the paneling is achieved by way of additional material along one or both edges of the panel. The additional material or thicker edge is substantial enough to provide the support required whereby a reduction in or prevention of a sagging or relaxing of the material is achieved.

In another embodiment of the invention, the paneling is scored in such a way that the paneling can be overlapped on one or both edges. The overlapped pieces of the material preferably have score marks that enable the user to punch out holes. The holes on the pieces of overlapped material preferably mirror each other or otherwise overlap, thereby creating a location for a rivet to be placed through the overlapped edges of the material. The overlapped and riveted piece of material would preferably result in a loop or a circle of material through which a pole can be threaded, the pole consisting essentially of metal, plastic, wood or other suitable material. The hanger may can be used to suspend the threaded rod with the paneling from the ceiling. In accordance with other aspects of the present invention, the use of adhesive mounts enables pieces of the paneling to be installed between the electronic enclosures. The adhesive mounts can be removably attached to the sides of the electronic enclosures and the appropriately sized panel pieces can be held in place on the surface of the adhesive mount, preferably through the use of a clip or other similar device. In addition to attachment by way of adhesive mount, the pieces can also be attached using zip ties or other suitable removable attachment accessories. The paneling mounted between the electronic enclosures may additionally be attached to other panel pieces, including the suspended panel pieces, by way of punching holes through the separate pieces of paneling, lining up the holes and riveting the material together. The additional supports and mounting facilitate installation and stability of the leader system, whereby the user essentially reduces the volume of space where air can travel so that it may be more efficiently return to the cooling units in data and equipment centers.

The installation of the materials is preferably done without the use of tools for cutting or hanging materials. The present invention is quickly and easily custom installed. The inexpensive and easy installation in combination with a reduction in the energy required to cool the data and equipment centers should provide the end user with a safer resolution to solving the crossover flow of air in equipment and data centers. In addition, the user is able to more effectively comply fire suppression regulations while at the same time reduce energy consumption in cooling equipment.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is view of the leader system as installed in a data center where the electronic enclosures are unevenly spaced and the heights are variable; and Figure 2 is a view of the leader system as installed in a data center where the electronic enclosures are adjacent and touching.

Figure 3 shows a data center where blanking panels on the electronic equipment are present, to prevent air flow through the equipment itself, as opposed to around or over the equipment.

Figure 4 shows a variety of embodiments of the rigid casing the eyelets the hanger hooks and the wire clip.

Figure 5 details the embodiments seen in element 29 of Figure 4, where in one embodiment the panel may be bent at a perforation or rounded between two adjacent perforations.

Corresponding reference numbers indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

The invention is a leader system for directing airflow from the back of electronic enclosures, in the hot aisle, toward the cooling unit in equipment and data centers, and further for at least partially preventing airflow from the back of the electronic enclosures, in the hot aisle, to the front of the electronic enclosures, the cool or cold aisle. The material used is preferably made of a lightweight and flexible material that can be easily modified and easily installed upon the enclosures and suspended from overhead, even preferably without destructive attachment to the enclosures or existing building structure. After installation, system components may be easily removed from the structures, both enclosures and building support.

Preferably, upon removal of the leader system, the components thereof can be easily further separated from each other and re-installed in a different configuration, which may become necessary to meet the demands of changes to the configuration of the enclosures. In the preferred embodiment of the present invention, the leader system pieces are scored to allow for break-apart sizing and shaping, such as the panels disclosed in pending U.S. Patent Application 1 1 /518,976. Due to their break- apart or tear-away construction the desired configuration of the leader system may be achieved with the use of minimal tools. In addition, the construction of the panels is preferably such that overlapping panels can be attached to one another through holes that may be punched through the material where score marks are made and then separate pieces can be attached together by overlapping the holes punched and fixing together with joiners such as rivets.

In the preferred embodiment, flexible panels of scored material are given a rigid top edge by attachment of a bracket, more preferably a plastic bracket. In this embodiment, a rigid casing, more preferably an aluminum casing, may be installed over the top the plastic bracket for additional support and to facilitate mounting. In this embodiment, an eyelet on the top of the rigid casing, centered along the edge of the panel, may enable suspension of the panel from the ceiling, preferably through the use of a single hanger rod or a modified hanger rod. The suspension of the panel requires the connection of a series of attachment accessories being linked together. Clearance from the ceiling in this embodiment is sufficient to allow for at least the 18 inches of space typically required for sprinkler heads, as is required by fire safety regulation. The present invention, however, encompasses and includes as an equivalent thereof the suspension of the panels directly from the ceiling, with no clearance between the tops of the panels and the ceiling. The scoring of the panels enables them to be sized by breaking apart panel pieces to accommodate the various sizes and shapes of the electronic enclosures, ceiling heights and to allow for attachment to juxtaposed panels in any direction.

In addition to the panels hanging overhead, in an embodiment a spacer panel can be custom fit to fill the space between the electronic enclosures. The attachment of a spacer panel to the sides of the enclosures may preferably be achieved through the use of removable adhesive clips, though any other suitable manner known in the art is acceptable. The spacer panels may be customized to fit between and attached to the enclosures. The spacer panels may be modified so as to continuously cover the space between the suspended panels and the enclosures, and between the enclosures from the bottoms of the suspended panels to floor. The continuous assembly of spacer panels and suspended panel substantially creates the leader system, where the leader system directs the air from the back of the enclosures to the air cooling system and prevents a substantial amount of crossover airflow from the back of the electronic enclosures to the front where the equipment is bringing in cold air from the cold air aisles.

In one embodiment, the plastic bracket used to provide structural support readily and removably snaps onto the panels. The plastic bracket is preferably made of PVC or similar material and is approximately 36 inches long, though it may be made of any suitable material and of any suitable length. For exemplary purposes, one such suitable plastic bracket is available at Popco, Inc. (Item No. SP'R-36), of Minnetonka, Minnesota, as of the date of the filing of the provisional application to which priority is claimed. The plastic bracket may be used alone or in conjunction with an aluminum casing for added stability.

In an embodiment where a plastic bracket is used, the plastic bracket may be attached to a rigid casing. Preferably the rigid casing is an aluminum casing and the plastic bracket is attached by way of a guide on top of the plastic bracket. Preferably the guide may be inserted within a complementary rail on the inside of the aluminum casing. The aluminum casing is preferably substantially the same length as the plastic bracket. For exemplary purposes, one such aluminum casing is available from Popco, Inc. (Item No. ALU/SP-36) as of the date of the filing of the provisional application to which priority is claimed.

In one embodiment, the eyelet used to attach the aluminum casing to the hanger rod is made of an aluminum material, though any other suitable material is acceptable. The eyelet preferably has a lip that fits inside a guide similar to that of the plastic bracket. The eyelet may be attached to and located along any position of the aluminum casing. For exemplary purposes, one such eyelet is available through Popco, Inc. (Item No. BRC-3) as of the date of the filing of the provisional application to which priority is claimed.

In one embodiment, the hanger rods have two hooks, each facing in the same direction and on opposite ends of a metal wire. The hanger rods are approximately 18 inches in length, so as to provide clearance from sprinkler heads located in the ceiling. For exemplary purposes, one preferred hook is available through Popco Inc. (Item No. WH-18) as of the date of the filing of the provisional application to which priority is claimed. Another embodiment includes a hook that has been modified so that instead of two hooks facing the same direction one hook is rotated around the axis of the hanger 90 degrees from the other hook. In one preferred embodiment, the metal hook can be non-destructively mounted to existing drop ceiling grids using metal wire clips. For exemplary purposes, one such suitable wire clip is available from Popco, Inc. (Item No. SQ-8) as of the date of the filing of the provisional application to which priority is claimed. Another piece of equipment that may be used to attach the hooks

IO to the ceiling involves is through a grid hanger rod. For exemplary purposes, one such suitable grid hanger rod is available from Popco, Inc. (Item No. GH-2) as of the date of the filing of the provisional application to which priority is claimed. Yet another piece of equipment that may be used to attach the hanger rod to the ceiling involves the use of carabiners. The grid hanger rod is preferably made from plastic.

In order to connect the panels between the electronic enclosures, a variety of different mounts may be used. In one embodiment, the mount is an adhesive mount, which may be employed to secure the mount to the side of an enclosure. The adhesive mount may comprise a clip attached to a base, where the base is at a substantially perpendicular angle to the opening of the clip, and where adhesive is on the side of the base opposite the clip. The adhesive may attach the mount to the electronic enclosure, and the clip may secure the appropriately sized spacer panel piece in between the electronic enclosure. For exemplary purposes, one such adhesive mount is available from Popco, Inc. (Item Nos. NSF-3, FMF-1 10-1", SGF-100-3", NNF-3, NNF-6 or SF-2-12) as of the filing date of the provisional application to which priority is claimed.

To create the leader system of the present invention, which comprises a continuous surface of panel pieces, ranging from approximately 18 inches below the . ceiling to the floor and in between the electronic enclosures, it is preferable that rivets be used to secure individual pieces of panel to one another. Such rivets may connect the suspended panel pieces to the panel pieces located between the electronic enclosures. The panels are preferably scored such in a way that holes may be placed in the panels. Two overlapping pieces of panel may be riveted together where the holes align. Repeating the aforementioned riveting of panel pieces throughout a data center results in the leader system of the present invention. This leader system is a

I l continuous liner of space from above and around electronic enclosures to the CRAC or other cooling units, so that airflow is directed toward the cooling units, and additionally is substantially prevented from being recycled to the fronts of electronic equipment, where cold air intake should be occurring.

Referring now to the figures, which show a particularly preferred embodiment of the present invention, Figure 1 shows the back of a series of electronic enclosures in a data or equipment center. The electronic enclosures 1, 2, 3 may be of variable heights. The leader system bridges the gaps between and above electronic enclosures and thus must be able to accommodate the variations in height of electronic enclosures. Above electronic enclosures 1 and 3, a single panel piece can accommodate the variations in height between the two different enclosures. The distance from the ceiling to the leader system can be controlled by using different lengths of hanger rod, as seen with the three different lengths of hanger rod in elements 4, 7 and 12. A wire clip 9 that is capable of attaching to the drop ceiling grid is present. The hanger rod 5 can attach to the wire clip by hooking onto the loop in the base of the wire clip. The hanger rod may then be attached to the aluminum casing 6 at the other end by way of an eyelet 8. The eyelets can be located anywhere along the length of the aluminum casing. In the preferred embodiment, the eyelet is centered in the aluminum casing that is centered on the paneling. The centering, or balancing of the weight of the material along both sides of the hanger rod requires fewer accessories for suspending the panels. The panels can be overlapped and riveted together at the edge of a panel 10. A hole may be punched through two juxtaposed pieces of paneling. The holes may be aligned and a rivet or other fastener can be placed through the holes to attach the panel pieces together. Spacer paneling 11 may be placed between electronic enclosures and secured by way of an adhesive mount. This piece of paneling, secured to the electronic enclosures, prevents, or reduces the flow of air from moving around and between the electronic enclosures to the front of the unit where the air intake in the equipment occurs.

The paneling may be attached to the hanger rod 12 directly, without the use of additional structural support, such as the plastic bracket and aluminum casing. This may be achieved by punching a hole through a scoring on the panel and inserting the hook of the hanger rod through the hole.

Figure 2 shows another data center, where the electronic enclosures are adjacent and touching. In this particular configuration, the leader system must be able to fill the gaps between the ceiling and the floor, but does not require filler between the electronic enclosures. The plastic bracket used for structural support in combination with the aluminum casing 6, 13 may be of varying lengths. The wire clip 9 and eyelet 8 are preferably connected by a hanger rod 4. The panels may be commercially available in a variety of sizes, such for example 24" by 48".

The leader systems in Figures 1 and 2 effectively reduce the volume of space where the air from the back of electronic enclosures may flow and generate a lead up to the CRAC or other cooling method. The reduction in volume of space where air may travel reduces the crossover of hot air from hot aisles to the front of electronic enclosures where cold air should be delivered for intake from electronic equipment. The reduction in the crossover helps reduce energy used to cool the equipment and reduces the volume of space cooled by the CRAC or other cooling units.

Figure 3 shows a data center where blanking panels 15 on the electronic equipment are present, to prevent air flow through the equipment itself, as opposed to around or over the equipment. In this figure, an angled hanger 14 is provided, which may be suitable for conditions where the hanger is at a fixed length and the distance between the ceiling and the top of the panel is less than the length of the hanger. The angled hanger may also aid in preventing the warping or other deformation of the panel. The continuous series of panels 17, 18 that comprise the leader system are shown, including both the suspended panels 18 and the spacing panels 17.

Figure 4 shows a variety of embodiments of the rigid casing 22, 23, 27, the eyelets 24, 28, the hanger hooks 20, 21, and the wire clip 25. Additionally, the plastic bracket or rigid casing may mount directly to the panel as seen in element 26. Also seen in Figure 4 is an embodiment where, when viewed from above, the rigid casings may be aligned in a substantially linear arrangement 32 or in an angled arrangement 29, where the solid dark lines represent the panel and where the hash marks thereon represent riveting. Figure 5 details the embodiments seen in element 29 of Figure 4, where in one embodiment the panel may be bent at a perforation 31 or rounded between two adjacent perforations 30.

Certain advantages associated with the present invention include: the flexibility of the system, such that a panel may be suspended by hanger hooks of any angle; the versatility of the system, such that the system may be installed to a suspended ceiling grid of 2' x 2' tiles or 2' x 4' tiles, among others; and, the modular nature of the system, such that, where the panels are scored to allow for break-apart sizing and shaping, the dimensions of the panels may be changed depending on server rack and ceiling height variances as well as fire code compliance.

While specific embodiments have been shown and described, many variations are possible. The particular shape of the segments and score lines and markings, scoring depths and aperture outlines including all horizontal and vertical orientations, dimensions and thicknesses may be changed as described to suit the needs of the data center. The material and its configuration and number of segments may vary although a preferred embodiment is shown and described. A series of different accessories: wire clips, hanger rods, adhesive mounts, rivets, or other attachment and connective means may be used and still be within the scope of the invention.

It should be understood that the aforementioned embodiments are for exemplary purposes only and are merely illustrative of the many possible specific embodiments that can represent applications of the principles of the invention.

Without departing from the spirit and scope of this invention, one of ordinary skill in the art can make various changes and modifications to the invention to adapt it to various usages and conditions, including those not specifically laid out herein. As such, those changes and modifications are properly, equitably, and intended to be, within the full range and scope of equivalents of the invention disclosed and described herein.

Claims

I claim:

1. An air leader system for controlling airflow comprising a lightweight, flexible panel having top edge; a bracket attached to and along the top edge of the panel, thereby forming a rigid, elongate top border to the panel, the border having an elongate top with a rail extending along the elongate top; a rigid casing attached to the bracket by way of a guide on the rigid casing, the guide being complementary to the rail; an eyelet, to which the rigid casing is attached by way of a guide and a complementary lip on the eyelet; a wire clip attachable to a ceiling, and a hanger rod comprising two hooks on opposite ends of the hanger rod, and wherein the hanger rod is attachable to the wire clip and the eyelet to enable suspension of the panel, the rigid casing and the bracket from the ceiling.

2. The air leader system of claim 1 , wherein the panel is scored to allow for break-apart sizing and shaping.

3. The air leader system of claim 1, wherein the bracket is plastic.

4. The air leader system of claim 3, wherein the bracket is approximately 36 inches long.

5. The air leader system of claim 1 , wherein the rigid casing is an aluminum casing

6. The air leader system of claim 1 , wherein the aluminum casing and the bracket are substantially the same length.

7. The air leader system of claim 1 , wherein the eyelet is made of aluminum.

8. The air leader system of claim 1, further comprising a spacer panel, where the spacer panel fills the space between electronic enclosures, the spacer panel having been attached to the sides of the enclosures.

9. The air leader system of claim 8, wherein the spacer panel continuously covers the space between the suspended panels and the enclosures, and between the enclosures from the bottoms of the suspended panels to floor.

10. The air leader system of claim 8, wherein the manner in which the spacer panel is attached to the sides of the enclosures is with an adhesive mount; where an adhesive mount comprises a clip attached to a base, where the base is at a substantially perpendicular angle to the opening of the clip, and where adhesive is on the side of the base opposite the clip, the adhesive attaching the mount to the electronic enclosure, and the clip secured to the spacer panel.

1 1. The air leader system of claim 9, wherein any two overlapping pieces of panel and spacer panel may be riveted together where holes scored thereon align.

12. An air leader system for controlling airflow comprising a lightweight, flexible panel having top edge; an eyelet attached to the top edge of the panel, the eyelet having a lip; a rigid casing attached to the eyelet by way of a guide on the rigid casing, the guide being complementary to the lip; a second eyelet, to which the rigid casing is attached by way of a guide and a complementary lip on the second eyelet; a wire clip attachable to a ceiling, and a hanger rod comprising two hooks on opposite ends of the hanger rod, and wherein the hanger rod is attachable to the wire clip and the second eyelet to enable suspension of the panel and the rigid casing from the ceiling.

13. The air leader system of claim 12, wherein the panel is scored to allow for break-apart sizing and shaping.

14. The air leader system of claim 12, wherein the rigid casing is an aluminum casing

15. The air leader system of claim 12, wherein the aluminum casing and the bracket are substantially the same length.

16. The air leader system of claim 12, wherein the eyelets are made of aluminum.

17. An air leader system for controlling airflow comprising a panel comprised of a lightweight and flexible material, where a hole has been punched through a scoring on the panel; a wire clip attachable to a ceiling; and, a hanger rod comprising two hooks on opposite ends of the hanger rod, wherein the hanger rod attaches to the wire clip, and further attaches to the panel by inserting the hook of the hanger rod through the hole.

18. The air leader system of claim 12, wherein the panel is scored to allow for break-apart sizing and shaping.

19. The air leader system of claim 1 comprising a plurality of panels, wherein the panels are overlapped and riveted together at the overlapping edges of each overlapping panel; wherein the panels are riveted together through one or more holes; where a hole has been punched through two juxtaposed panels, the holes have been aligned, and a rivet or other fastener is placed through the holes.