US 3853367 A
Cabinet has a top frame and base frame around which the housing is wrapped on three sides so that the top frame and base frame define the size of the cabinet and provide dimensional rigidity to the housing. The housing is bent from a single panel of honeycomb material. Front closure frames have tongues extending into grooves in the front edges of the housing for adjustment during assembly to finalize front-to-rear dimensions of the cabinet and provide a planar cabinet front.
Description (OCR text may contain errors)
ilited States Pate Jamison et al. I
[451 Dec. 10, 1974 1 CABINET  Inventors: John W. Jamison, Costa Mesa; Dan
R. Veronda, Fullerton; Roy E. Denner, Placentia, all of Calif.
 Assignee: Hughes Aircraft Corporation,
Culver City, Calif.  Filed: Feb. 9, 1972 21 Appl. No.: 224,839
 US. Cl. 312/259, 312/257 R  Int. Cl. A47b 43/00, A47b 47/00  Field of Search 312/214, 357, 138, 262 T;
 References Cited UNITED STATES PATENTS 1,496,525 6/1924 CoCo 49/505 2,149,882 3/1939 Clements 312/259 UX 2,226,670 12/1940 Pratt et a1. 312/214 2,274,765 3/1942 Zalkind 312/258 UX 2,360,451 10/1944 Stone 312/257 R 2,477,942 8/1949 Renton 49/505 X 2,678,705 5/1954 Haines et a1. 312/257 UX 3,118,559 1/1964 Stricker et a1. 1 i 220/14 X 3,297,189 1/1967 Carrasse .[312/214 X 3,472,571 10/1969 Himelreich 312/259 3,485,545 12/1969 Newman et a1 312/258 3,675,809 7/1972 McGrew 220/9 B R22,425 1/1944 Rosenthal 312/259 Primary Examiner-Paul R. Gilliam Attorney, Agent, or FirmA. A. Dicke, Jr.; W. H. MacAllister, Jr.
[ 57 1 ABSTRACT Cabinet has a top frame and base frame around which the housing is wrapped on three sides so that the top frame and base frame define the size of the cabinet and provide dimensional rigidity to the housing. The housing is bent from a single panel of honeycomb material. Front closure frames have tongues extending into grooves in the front edges of the housing for adjustment during assembly to finalize front-to-rear dimensions of the cabinet and provide a planar cabinet front.
4 Claims, 8 Drawing Figures PATENTE' LEE 1 01974 sum 1 nr 2 CABINET BACKGROUND This invention is directed to a cabinet, and particularly a cabinet which can be subjected to dynamic laods associated with shock and vibration environments, and for enclosure of equipment, such as electrical equipment.
The prior art includes many styles of cabinets for enclosing various types of goods in different environments. Cabinets are employed to support equipment and to protect equipment from the external environment. In the most difficult cases, the external environment includes dynamic loading with the presence of shock and vibration applied to the cabinet. Such environments are found in many military applications, in the air, on the land, and on the water. In these cases, the cabinet must be sufficiently strong to withstand the dynamic loading.
Two basic approaches have been used in previous cabinets to which such dynamic loading is to be applied: the corner-post" design and a stiffened sidewall construction. The corner-post design is characterized by rigid, heavy posts at each of its corners, with reinforced shear panels on the sides and back. The loads developed within the cabinet due to dynamic loading of the cabinet are routed to the corner posts by means of brackets, and then are transferred to the base and top support of the cabinet through the corner posts.
The piece-part assembly approach inherent in the corner-post design necessitates many mechanical fasteners and welding. With increased loading intensities and/or payload increases, it becomes necessary to reinforce the walls of the cabinet with gross additions of stiffeners, including hat sections, doublers, and stringers. While these stiffeners provide additional crosssectional moment of inertia, they also increase manufacturing costs, because a considerable amount of assembly time is required for the installation of such stiffeners. The corner-post design of cabinets for dynamic loading is thus shock-load limited, i.e., at high load intensities, the amount of routing bracketry and stiffeners needed to transfer the loads from within the cabinet to the base and top is of such magnitude that the cabinet is excessive in cost and weight.
The present alternative construction to cabinets of the corner-post design for high load environments comprises cabinets of stiffened sidewall construction. The
stiffened sidewall construction relies on large crosssectional moment of inertia of the cabinet sidewalls. These sidewalls distribute loads developed within the cabinet and thus are capable of high dynamic loads. The sidewalls may be built up using bracket-like piece parts, or they may be extrusions. The extrusion sidewalls are generally 1% to 2 inches thick. In such construction, the cabinet backwall is merely a thin shear panel which is welded to the stiffened side panels.
In theory, the stiffened sidewall construction reduces the number of piece parts while, at the same time, provides added stiffness to support larger payloads in high loading environments. However, like the corner-post design, the cabinets which employ built-up sidewalls are also shock-load limited. Cabinets having extruded sidewalls do not have this limitation. However, extrusions are major elements in such construction and necessitate expensive dies. Of course, a panel produced SUMMARY In order to aid in the understanding of this invention, it can be stated in essentially summary form that it is directed to a cabinet having a unitary housing extending around two sides and the back and secured to a frame which holds the housing to size. In one aspect of the invention, the housing is of laminated panel construction and, in another aspect, the housing has grooves in the front edge thereof into which a front closure frame extends.
Accordingly, it is an object of this invention to provide a cabinet which is suitable for the housing of equipment in an environment subject to dynamic shock and vibration loading. It is another object to provide a cabinet which has a one-piece housing extending around the sides and back of the cabinet. It is another object to provide a single wrap-around housing of metallic skin material which shields the equipment enclosed within the cabinet to reduce the level of radio frequency interference and electromagnetic interference between the cabinet contents and the exterior environment.
It is a further object to provide a cabinet which has a frame base around which the housing is wrapped, which frame base establishes the exterior dimensions of the cabinet housing. It is a further object to provide a cabinet having a housing formed of honeycomb panel for strength and lightness of weight, consistent with a dynamic environment. It is another object to provide front closure frame sections which are adjustable with respect to the cabinet housing so that the front of the cabinet can be adjusted during manufacture. Other objects and advantages of this invention will become apparent from a study of the following portion of the specificatiomthe claims, and the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of a cabinet constructed in accordance with this invention.
FIG. 2 is an exploded view of the cabinet showing the major parts thereof.
FIG. 3 is an enlarged vertical section, with parts broken away, taken along the line 3-3 of FIG. 1, showing the details of the upper front and rear corners.
FIG. 4 is an enlarged horizontal section through the cabinet near the base, taken generally along the line 4-4 of FIG. 1.
FIG. 5 is an enlarged vertical section, with parts broken away, taken generally along the line 5-5 of FIG. 4.
FIG. 6 is an enlarged horizontal section, with parts brokenaway, through one of the front corners of the cabinet of FIG. 1, taken generally along the line 6-6 of FIG. '1 showing the preferred embodiment of the front closure frame. 1
FIG. 7 is similar to FIG. 6 showing another embodiment of the front closure frame.
FIG. 8 is also similar to FIG. 6 showing a third embodiment of the front closure frame.
DESCRIPTION The cabinet 10 illustrated in FIGS. 1 and 2 is an example of the cabinet construction, in accordance with this invention. The particular cabinet illustrated in these figures is exemplary of the various sizes and styles in which a cabinet can be built, in accordance with this invention. Various other configurations employing the concepts of this invention can be constructed.
The cabinet 10 comprises a cabinet housing 12 which forms the side and back of the cabinet. The cabinet sides are indicated at 14 and 16, with the back shown at 18. Housing 12 is illustrated in its preferred embodiment as being a laminated honeycomb panel. In the preferred embodiment, it has a metallic inner and outer skin and a metallic honeycomb therebetween. Preferably, all are aluminum and are secured together as by adhesive. Other forms of honeycomb can be used but, in any case, at least the outer skin should be metallic. In some cases, a core material in the housing between the skins of rigid synthetic polymer composition foam would be useful. Furthermore, several layers of core material, such as a layer of metallic honeycomb and a layer of polymer composition rigid foam, with a divider skin, can be used. As another embodiment, the housing can be a single layer of material, such as bent sheet metal, but this type of construction does not have the dynamic load-resisting properties that a metallic honeycomb has. Thus, the preferred embodiment is a metallic honeycomb with aluminum inner and outer skins, as well as aluminum honeycomb.
The bending of honeycomb material into suitable configurations for use as a cabinet housing is taught in more detail in US. Pat. No. 3,753,559. The entire disclosure of that patent is incorporated herein by this reference. See also its division, Ser. No. 351,699, filed Apr. '13, 1973. In summary, a flat, laminated, metallic honeycomb panel can be bent from planar condition into a shaped condition having corners therein by bending the inner skin outward to crush the honeycomb between the skins in the region of the bend. The bends of the inner and outer skins are such that the surface distance around the bent corner is the same on the inside skin as on the outside skin so that the laminated honeycomb panel away from the bend is not appreciably distorted, but remains planar, with its normal strength characteristics. Such bends are illustrated at the rear corners of the cabinet 10 in FIGS. 2 and 4.
Prior to bending, the housing 12 is built up into flat panel. It is laid up with aluminum closeout blocks along the upper and lower edges, except in the bend areas. These closeout blocks structurally reinforce the edges of the cabinet and are utilized to obtain a solid attachment. Additional cutouts for connectors, air venting, etc., are also closed out with aluminum blocks to provide adequate structural termination at the edges of the skin. Aluminum honeycomb core material fills the remaining portion of the sandwich core, with aluminum skins completing the panel.
While in flat condition, the panel can be inspected, inserts made and potted in place, and the like. Furthermore, cutouts can be machined, base bolt holes can be drilled and threaded so that details of the housing 12 can be manufactured with a minimum of difficulty with the housing panel in the flat condition. When built up in this way, the aluminum skins carry the load in the plane of the panel, while the core carries shear stresses and resists compression loads normal to the plane of the panel. When in the formed condition, after the corner bends are made, shock loads imparted to the cabinet will be absorbed in shear by the honeycomb core and transferred uniformly to the panel skins.
Once in the formed condition, the housing 12 is maintained in shape and dimensionally stabilized by means of top frame 20 and base frame 22. As seen in FIGS. 2 and 3, top frame 20 is of rectangular configuration of such size as to equal the interior dimensions of the finished cabinet. It is formed of structural angle. Shear bolts 24 engage through the top frame into the closeout bar 26 positioned between the skins of the honeycomb at the upper edge of back 18. A plurality of these shear bolts 24 are positioned around the sides and back of top frame 20 and engage into the corresponding parts of the upper end of housing 12. These bolts pull the housing into shape and keep it that way.
Similarly, base frame 22 is secured within housing 12 at the lower portion thereof to serve as the bottom of the cabinet. In normal duty operations, shearbolts such as shear bolts 24 can be engaged outward through the base frame into a closeout bar on the bottom of housing 12. However, in higher dynamic duty circumstances, as in the preferred embodiment, tension bolts 28 have their heads positioned interiorly of the flanges of base frame 12 and extend outwardly to be threaded into closeout bars 30 and 32 positioned on the bottom of sides 14 and 16 in the bottom of back 18. These tension bolts 28 draw the bottom of housing 12 into dimension and shape and hold it there. However, in order to endure even heavier dynamic loading, additional bolts are engaged through the bottom of the housing 12 and base frame 22. Shear bolts 34 have heads in counter bores recessed into the exterior of housing 12, into the closeout bar in the bottom thereof, and these shear bolts extend through base frame 22 to have securing clamp nuts thereon, as seen in FIG. 4. This provides a highly rigid structure and securement between the housing 12 and base frame 22. The base frame 22 has boltdown holes'36 in the corners to bolt down the entire cabinet 10 onto an appropriate base. In dynamic loading environments, the top frame is also preferably secured to the environment base. These two frames, the top frame 20 and base frame 22, to which the housing 12 is secured, provide a unitary rigid structure. In order to protect the top from the elements, cabinet cover 38 is secured down over the top of top frame 20 in the upper ridges of the housing 12.
As illustrated in FIG. 2, the upright front edges of the left and right sides 14 and 16 of housing 12 have closeout bars 40 and 42 positioned between the skins and abutting the honeycomb. FIG. 6 illustrates the closeout bar 42 in more detail. Closeout bar 42 has a groove 44 therein, and a similar groove 46 is formed in the front edge of closeout bar 40. These grooves 44 and 46 have parallel sidewalls to receive the tongues of front closure frame.
In the preferred embodiment shown in FIGS. 2 and 6, front closure frames 48 and 50 are L-shaped, including tongue 52 which extends into the groove 44. The two front closure frames 48 and 50 are adjusted so that the front-to-back dimension of the cabinet is correct. Thereupon, the front closure frames are secured into place, as by rivets 54 and, preferably, additional adhesive securement. Door 56 is, thereupon, pivotally mounted upon frame 50 by appropriate hinges so the door serves as an access closure to the interior of cabinet 10.
In the embodiment of Fig. 7, front closure frame 58 comprises a tongue 60 to which is secured a front closure bar 62. These parts are bolted together with clearance around the bolt shank so that lateral adjustment of front closure bar 62 is possible. Such provides the desirable lateral opening size adjustment of the door opening.
in FIG. 8, the front closure frame 64 is as wide as the thickness of the housing. Such construction is desirable where there may be a plurality of doors, or where a minimum construction thickness is required. With respect to the constructions of FIGS. 7 and 8, after the frames are adjusted, the tongues are secured in place by rivets and, preferably, also by adhesive means, similarly as described with respect to construction of FIG. 6.
From this construction, it can be seen that the housing 12, being of a single sheet of material bent into configuration to define the sides and back of the cabinet, serves as the primary load-bearing element of the cabinet. The front closure frames carry a proportion of load, and also serve to form the cabinet front and define the door opening. ln extreme vibration environments, the front closure frames structurally reinforce the cabinet sidewalls, especially when the cabinet is excited by side-to-side vibrational inputs. The front closure frames are bolted through to the base frame 22 to provide a unitized construction, thereby increasing its stiffness characteristics. The load-bearing characteristics of the housing 12 result from its sandwich laminate construction, it being formed out of a single piece of material having strength in bending and shear. As stated above, the material of the housing is preferably aluminum honeycomb.
Cabinet 10, thus, is constructed in such a manner as to be economic of construction and yet be suitable for dynamic loads, such as shock and vibration. The construction is such that radio frequency interference and electromagnetic interference between the cabinet contents and the exterior environment is minimized. Simple modifications of the base and housing permit different shapes and dimensions which are able to accommodate wide variations in payload, load distribution, cabinet geometry, top support and environmental require-.
ments. Furthermore, the design lends itself to the latest manufacturing techniques. For example, tape control drilling machines can be employed for speed and accuracy to locate threaded inserts in the flat housing structure before bending. In this way, no expensive dies, moulds, or tooling are required, and a high-strength cabinet is provided.
This invention having been described in its preferred embodiment, it is clear that it is susceptible to numerous modifications and embodiments within the ability of those skilled in the art and without the exercise of the inventive faculty. Accordingly, the scope of this invention is defined by the scope of the following claims.
core therebetween attached to and rigidizing said metal skins with the honeycomb core cells being normal to said skins, said panel being bent at the cabinet corners so that said panel defines the sides and back of said housing, said honeycomb core being crushed at said corners and said panel skins extending continuously around said corners, said panel being secured to said top frame and said base frame so that said top frame and said base frame retain said panel in a lateral position, said laminated honeycomb panel carrying the principal physical loads on the cabinet;
a closeout bar positioned between the panel skins at each of said edges, said closeout bars each having means for interengaging thereon;
front closure frames, said front closure frames each having means for interengaging thereon, said means for interengaging on said front closure frames being interengaged with said means for interengaging on said closeout bars.
2. The cabinet of claim 1 wherein said front closure frame has a laterally extending front closure bar thereon for defining a door opening in the front of said cabinet.
3. The cabinet of claim 1 wherein said means for interengaging comprises a groove and a tongue within said groove, said tongue and said groove each having substantially parallel sides so that said front closure frame can be adjustably positioned with respect to said housing while said tongue is at least partially positioned within said groove. 1
4. The cabinet of claim 3 further including a door hingedly mounted upon one of said front closure frames and extending substantially to the other of said net.