FIELD OF THE INVENTION
- BACKGROUND OF THE INVENTION
The present invention relates generally to securing devices and, more particularly to securing devices including securing devices for equipment, equipment cabinets and earthquake-resistant securing.
When constructing installation plants for e.g. telephony, telecommunication or electricity networks, it is common practice to arrange the equipment in cabinets for sake of e.g. space-saving and easy access during installation. The cabinets can be of the closed type, having wall elements essentially on all sides, or of the open rack type.
When building up plants of that kind in earthquake zones, it is desirable to mount the cabinets to the floor or support structure in an earthquake safe way, such that the cabinets do not fall or become displaced during an earthquake, since it is important that this kind of infrastructure installations will be maintained and still function even after the earthquake.
In cases where the support structure is a concrete slab or a concrete floor structure, it has been common, according to prior art, to secure the cabinets directly into the concrete by means of anchor bolts, e.g. expander bolts or chemical binding anchor bolts. Normally one bolt in each corner of the cabinet.
There are essentially two main types of equipment cabinets in use today, which require somewhat different ways of securing the cabinets to the support structure. In one embodiment the cabinet is provided with normally four stem feet, i.e. supporting feet each having a stem or shaft part and a foot part, which bear against the concrete floor and which has a larger cross sectional measure than the stem. When securing cabinets equipped with stem feet, it is common practice to use a clamping beam having a fork formation in each end, more exactly each comprising two fork arms and an intermediate slot in the longitudinal direction of the clamping beam. During mounting the clamping beam is positioned between pairs of stem feet, such that at least two clamping beams are required to secure each cabinet. The clamping beams are secured by anchor bolts to the concrete floor and the length of each clamping beam is telescopic variable. In this way the fork formation in each end of the clamping beam can be moved towards the respective stem foot and engage the stem foot, such that the fork arms bear against the upper side of the foot part on each side of the stem, which accordingly is positioned in the slot of the fork formation. When tightening the anchor bolts, the clamping beam is drawn towards the concrete floor and hence presses the stem feet immovable against the floor.
In another common embodiment of an equipment cabinet, the stem feet are dispensed with and instead the cabinet is secured by means of anchor bolts from the inside of the cabinet, wherein the anchor bolts extends through a frame structure of the cabinet and into the concrete. Accordingly, no clamping beam is required in this embodiment.
However, when performing the securing of the cabinets to the concrete floor, in one of the ways described above, the required thickness of the concrete is rather large. Generally a thickness of at least 160 mm of good quality concrete, is required for securing a cabinet in an earthquake-safe way when using four anchor bolts. Otherwise the cabinet will be insufficiently secured. In many cases it is desired to rebuild an old plant from a conventional to an earthquake-safe plant. If then the concrete layer of the floor is too thin, the presently used alternative is to remove all the equipment and cast on a new concrete layer. This involves extensive as well as expensive work, resulting in a long downtime for the plant. Likewise, in many cases at new construction, the concrete layer must be made thicker, in order to build earthquake-safely, than it perhaps otherwise would have been made.
- SUMMARY OF THE INVENTION
When mounting the cabinets earthquake-safely, it is also necessary to drill comparatively deep holes into the concrete, which necessitates the use of rather big and powerful equipment. Deep hole drilling also increases the risk to impinge on reinforcement bars or other obstacles.
The object of the invention is to enable earthquake-safe mounting of equipment cabinets on a concrete support structure in a simple and inexpensive way, at the same time as the necessary concrete layer may be thinner than with the prior art technique.
According to one embodiment of the invention, a securing device is provided comprised of a comparatively thin upper assembly plate, which may be made of steel, and at least four spacer plates or foot plates, which also may be made of steel, which are mounted on the assembly plate and are adapted to bear against the concrete floor. The assembly plate and the spacers may present a common hole pattern, namely on one hand common through holes for securing the securing device onto the concrete floor by means of anchor bolts, and on the other hand threaded holes for securing the cabinet onto the securing device. The threaded holes may be through holes, but need not necessarily be so since the bolts holding the cabinet generally, but not necessarily, end before they reach the underlying concrete.
A device as set forth above, presents a number of advantages over the prior art. Among other things the device may present a unitary assembly which the cabinet interacts to secure the cabinet onto the concrete floor. Moreover, it may facilitate and allow the use of a larger number of anchor bolts, compared to the prior art, to fasten the device, and hence also the cabinet, to the concrete floor. In the prior art it is more difficult to increase the number of anchor bolts, since the structure of the cabinet itself sets restrictions of where it is possible to place the bolts. Also, bolts generally were not placed to close to each other since this might cause cracking of the concrete. With a securing device according to the present invention, more freedom is given to place the bolts in the most optimum positions. Having a larger number of anchor bolts in the concrete causes the forces acting on the cabinet during an earthquake to be more evenly over the concrete floor, thereby making it possible to use shorter anchor bolts to hold the same load. This in turn decreases the required concrete thickness.
Instead of a thin assembly plate having spacer plates, a thick plate may be used. Also, the thickness may be uniform or variable. With a thick plate, however, the device becomes more expensive and more cumbersome to handle during mounting, due to the increased weight. The choice of the plate thickness depends upon weight, cost and other considerations. By using a thin and variable thickness securing device as described according to an embodiment of the invention, a device is achieved which has the required thickness and strength only in the areas where this is necessary, i.e. in the areas where the securing device is secured to the concrete floor and the cabinet is secured to the securing device. This is normally in the corners of the cabinet. However, it will be understood that the cabinet may be secured to the securing device anywhere relative to the cabinet. The securing device may provide a smooth and even upper surface which facilitates displacing of the cabinet to the correct position during mounting. The upper assembly plate also may be configured to ensure that the mutual distances between the threaded holes for securing the cabinet, are maintained as required so as to allow and facilitate the mounting of the cabinet.
The securing device according to an embodiment of the invention, also facilitates the installation of the cabinet in that the securing devices may be mounted in advance on the concrete floor. This represents the most time-consuming work during installation of cabinets, since it involves position setting for the cabinets as well as drilling into the concrete floor. When all of the securing devices are positioned, the cabinets can quickly and easily be secured to the securing devices by simply threading of the mounting bolts into the threaded holes in the securing device, with or without a clamping beam as described hereinbefore.
BRIEF DESCRIPTION OF THE FIGURES
It is to be understood that the invention may be modified in many different ways within the scope of the claims. For example, the size and form, including thickness of the securing device may be altered as well as the size, number and position of the spacer plates on the assembly plate. Also the number of anchor bolts into the concrete floor may be varied. In the detailed description of an embodiment of the invention, which is given hereinafter with reference to the accompanying drawings, an embodiment is described making use of a clamping beam for securing of a cabinet equipped with stem feet. However, the invention is also applicable in combination with a cabinet lacking any stem feet and hence having no need for a clamping beam to secure the cabinet. Instead the mounting bolts are passed through the cabinet frame and treaded into the securing device.
The above described features and advantages of embodiments of the present invention will be more fully appreciated with reference to the accompanying description and drawings, in which:
FIG. 1 is a view from above of a securing device according to an embodiment of the invention, with the positions of spacer plates indicated with dash and dot lines;
FIG. 2 is a view from above of a spacer plate;
FIG. 3 is a cross section through the securing device according to FIG. 1, secured to a concrete floor by means of anchor bolts;
FIG. 4 is a view from above according to FIG. 1, with two clamping beams, each holding two stem feet, mounted onto the securing device;
FIG. 5 is a partly exploded cross section according FIG. 2, showing an embodiment in which a clamping beam is used to mount two stem feet onto the securing device; and
FIG. 6 is a perspective view of a cabinet secured to a concrete floor using a securing device according to an embodiment of the invention.
A securing device according to an embodiment of the invention comprises an assembly plate 1 and, in the preferred embodiment, four spacer plates 2 which are positioned in the respective corners on the bottom side of the assembly plate. As is evident from the drawings, the assembly plate 1 may be considerably thinner than each of the spacer plates 2, although this is not a requirement. According to one embodiment, the assembly plate has a thickness in the range of 3-5 mm, preferably about 4 mm, whereas each of the spacer plates has a thickness in the range of 13-17 mm, preferably about 15 mm. Moreover, the assembly plate has a length of about 300 mm and a width of about 600 mm. It will be appreciated, however, that the surface area is variable depending on the size of the cabinet to be secured and which ranges have been stated above, these ranges do not limit the size, form or thicknesses that may be implemented advantageously according to embodiments of the present invention. For example, the plates 1 and 2 may have the same thickness or different thicknesses and may have thicknesses inside of or outside of the ranges set forth above.
The spacer plates 2 may be mounted to the bottom side in the corners of the assembly plate 1, by means of four bolts 3 each. Also, further holes may be formed in linear relationship through the assembly plate and each spacer plate, namely for each spacer plate two through holes 4 and two threaded holes 5. Having two, or even more, threaded holes 5 for every spacer plate, may be implemented, though it is not necessary, to offer different mounting positions for the cabinet.
The through holes 4 may be used, as is shown in a cross section of the securing device and a concrete floor 6 in FIG. 3, for securing the device to the concrete floor using anchor bolts 7 in the through holes 4, wherein the spacer plates 2 may bear against the floor. Accordingly, in the mounted state of the securing device, it may have a smooth and even upper surface, though this is not necessary.
In FIG. 5 is shown two stem feet 8, each comprising a stem 8′ and a foot portion 8″, having a larger cross sectional measure than the stem, which are to be placed upon the upper surface of the assembly plate. The stem feet may form part of a cabinet 12, as shown in FIG. 6, and function to support the cabinet on the floor structure. Alternatively, the cabinet may be designed to be secured without the use of feet. When stem feet are present, to secure the stem feet onto the securing device, a clamping beam 9 may be used. The clamping beam 9 is comprised of three separate beam parts 9′, 9″, 9′″ which may be telescoping lockable and releasable in relation to each other using locking bolts 10 to render the clamping beam variable in length. The beam parts 9′ and 9′″ may be identical and form the respective ends of the beam. Each of these endparts is formed with a fork formation in the outer end, comprising two fork arms 11 and an intermediate slot in the longitudinal direction of the clamping beam.
When securing the cabinet onto the securing device, the clamping beam 9 may be adjusted to correct length through telescoping and subsequent locking by the bolts 10. With a correct adjusted length, the fork arms 11, in the respective end of the clamping beam, may bear against the upper side of the foot portion 8″ and the stem is positioned in the slot between the fork arms. Thereafter the clamping beam may be secured to the securing device by screwing securing bolts 13 through elongated slots 14 in the clamping beam and into the threaded holes 5 in the securing device. According to this technique, the stem feet are pressed against the upper side of the assembly plate 1 and held firmly by the clamping beams. It is contemplated, however, that any other technique may be used to hold the stem feet firmly against the assembly plate.
Any cabinet foot configuration is possible. For example, as is evident from FIGS. 4 and 6, the distance between the stem feet at the front side of the cabinet, is smaller than the distance between the stem feet at the rear side of the cabinet. Consequently, the front clamping beam has a smaller assembled length than the rear clamping beam and also different threaded holes 5 are used for the securing bolts 12. Any other configuration, including more feet, is possible.
In FIG. 6 is shown, in a perspective view, a cabinet 12 secured to a concrete floor 6 using a securing device, according to an embodiment of the invention. In the figure is also shown connecting plates 15, 16, which are used to interconnect securing devices for positioning cabinets back-to-back and side-to-side, respectively. These connecting plates 15, 16 may be connected using bolts into holes 17 (shown also in FIG. 1) in the assembly plate 1. However, any convenient fastening or securing device may be used other than bolts.
The material used to make the plates may be any material that has sufficient strength to secure a cabinet, device, equipment or any other object to a concrete floor. The material may comprise, for example, a metal such as steel or a steel alloy. However, any other material, including non-metals may be used as long as the materials have sufficient strength for the application.
While particular embodiments of the present invention have been shown and described, it will be understood that changes may be made to those embodiments without departing from the spirit and scope of the present invention. For example, which securing equipment cabinets has been described, it will be understood that any equipment or object may be secured to any type of floor with a securing device as described herein.