Method of construction of insulated cabinet

An improved insulated cabinet, such as a refrigerator or freezer cabinet, is constructed by first manufacturing a rigid structural frame to close tolerances and then loosely attaching the remaining components of the outer shell of the cabinet by mechanical connections which permit some relative movement between the main frame and the other outer shell components. The outer shell, with an inner shell positioned within it in spaced relationship to define an insulating cavity, is then placed in a jig which positions precisely the components of the outer shell in their desired final relationship. The loose connections between the outer shell components permit them to be shifted by the contacting surfaces of the jig into the precise relative positions desired, and while the outer shell components are so supported by the jig, a hardenable insulating material is introduced into the cavity, where, upon hardening, it fixes the outer shell components and the inner shell in their desired positions relative to each other. Any convenient form of mechanically interconnecting the outer shell components which permits relative movement can be utilized, such as deforming or crimping contacting surfaces, utilizing self-tapping screws and combinations of these connections.

BACKGROUND OF THE INVENTION 
In conventional insulated cabinet constructions the various components 
making up the cabinet are rigidly attached to each other, usually by 
continuous welds along their contacting surfaces. To insure that the 
components are positioned properly with respect to each other a great deal 
of care must be taken during the welding process, usually requiring that 
the parts be positioned by jigs at each welding step to insure any 
deviation of the components from their desired positions relative to each 
other falls within fairly close tolerances. Obviously this is a very time 
consuming process and appreciably increases the cost of the resulting 
cabinet. 
More recently, cabinet constructions have been proposed wherein precision 
welding of all of the components is eliminated and the hardenable 
insulating material generally associated with cabinets of this type relied 
upon, not only for its insulating properties, but to structurally 
interconnect the cabinet components. Assemblies of this type are shown in 
French Pat. No. 1,362,178, allowed Apr. 20, 1964 and published in French 
Official Gazette No. 22 of 1964; and U.S. Pat. Nos. 3,948,407 and 
3,948,410. 
In the above noted French patent the desired positional relationships 
between the components of the cabinet are apparently attained in some 
manner by use of an appropriate supporting mold. In the two U.S. patents 
the outer shell of the cabinet of each is formed of a one-piece wrap 
around construction which is held on a base, an inner liner inserted in 
the outer shell and insulating material foamed between the outer shell and 
the inner liner. 
Thus, in more recent prior art cabinet constructions a supporting mold of 
some type which is capable of holding each of the various cabinet 
components in position while insulating material is foamed between them 
must be utilized, or a sheet of steel or the like of rather substantial 
size must first be formed into a one-piece, wrap around type outer shell. 
SUMMARY OF THE INVENTION 
In accordance with the present invention an insulated cabinet is provided 
which does not rely upon the use of a support or fixture of some type to 
hold the cabinet components together nor must a single large sheet of 
steel or other material be utilized to form, in effect, an integral, wrap 
around type outer shell. 
Instead, a main structural frame is first constructed to rather precise 
dimensional tolerances and with the main frame serving as the basic 
component of the cabinet outer shell, additional outer shell components 
are loosely attached to each other and the main frame to form an outer 
shell in which the components are only approximately positioned with 
respect to their desired final positional relationship and capable of 
limited movement with respect to each other. 
Thereafter, the loose assembly of components, with an inner shell 
positioned within, it is placed in a jig which squares up the outer shell 
by shifting the loosely connected components thereof into their desired 
final positions and, while the outer shell components and the inner shell 
are held in this manner by the jig, a hardenable insulating material is 
introduced into the insulating cavity defined by the inner and outer 
shells and fixes the formerly loosely fitted outer components in position 
with respect to each other and the inner shell. 
Thus, it is unnecessary to reply upon some sort of supporting mold to hold 
each of the cabinet components in position for foaming nor is it necessary 
to form a large, substantially one-piece wrap around shell to eliminate 
the prior art disadvantage of precision welding each of the cabinet 
components together.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An insulated cabinet, such as a freezer or refrigerator cabinet, is shown 
at 10 in FIG. 1 of the drawings. The cabinet includes an enclosure 12 
supported by legs 14 and provided with doors 16, while an upper trim 
section 18 conceals various mechanical components usually associated with 
cabinets of this type. While a particular type of cabinet structure is 
shown for purposes of illustration in FIG. 1 and is described below, it 
will be apparent that the principles of the present invention are capable 
of general application to a variety of structures of this general type. 
With reference to FIGS. 4 through 7 of the drawings it will be seen that 
the base cabinet structure includes an inner shell 20, preferably formed 
of steel or molded plastic, and an outer shell 22, preferably formed of 
steel, which together define an insulating cavity 23 between their 
opposing surfaces. The inner shell 20 may be formed in any convenient 
manner and the particular method of construction does not per se form part 
of the present invention. 
With continued reference to FIGS. 4 through 7 and additionally FIG. 2, it 
will be seen that a basic component of the outer shell 22 is a precisely 
manufactured structural frame 24. Frame 24 includes upper and lower 
horizontally extending rails 26 and 28, respectively, vertically extending 
stiles 30 and 32 and a central mullion 34. As noted above, while a 
particular size and shape cabinet has been selected for purposes of 
illustration it will be apparent that both the size and shape can be 
varied within the scope of the present invention and the particular 
configuration of the main structural frame 24 can be varied accordingly. 
The components 26, 28, 30, 32 and 34 are constructed to close tolerances 
and joined at their contacting surfaces by continuous welds while the 
components are held in precise relationship to each other by a welding 
fixture. Thereafter the welded joints are ground to provide a flush outer 
surface and the entire main structural frame 24 polished to provide, in 
effect, an integral, rigid structural frame precisely manufactured within 
close dimensional tolerances. 
Following construction of the main structural frame 24 additional 
components of the outer shell 22 are loosely attached to it and to each 
other by mechanical connections which permit limited relative movement 
between the various components. 
For example, a shell top assembly 36 including a collar assembly 38 has the 
components thereof interconnected by crimping using a standard crimping 
tool and the shell top assembly and the upper rail 26 are also 
interconnected by a series of crimps formed along their contacting 
surfaces. 
As seen in FIG. 9, the rail 26 is provided with a channel into which a 
flange of the shell top assembly 36 is inserted to form a connection 42 
and a series of dimple-like depressions is formed through the three 
thicknesses of metal by a standard crimping tool at a series of spaced 
points along the contacting portions of the rail and shell top to provide 
loose mechanical connections which permit limited relative movement. A 
typical crimp type connection is shown in cross section at 44 in FIG. 11 
of the drawings. 
A bottom shell assembly 46 consisting of a central panel 48 and end 
channels 50 is formed with members 48 and 50 having interfitting portions 
52 similar to the portion 42 of the top rail and shell top assembly as 
best seen in FIGS. 2 and 5 of the drawings. The interfitting portions 52 
are then secured with crimp type mechanical connections similar to those 
shown in FIG. 11 of the drawings again, permitting some relative movement 
between the components of the bottom shell assembly. 
The bottom shell is then connected to the lower horizontal rail 28 and a 
back panel 54, as seen in FIGS. 7 and 10 of the drawings, by interfitting 
portions 56 and 58, respectively, which are then crimped in the manner 
shown in FIG. 11 of the drawings. At this point the partially completed 
outer shell is as shown in FIG. 2 of the drawings, with only the main 
structural frame 24 of rigid construction and the remaining components 
loosely attached thereto and capable of limited relative movement. 
Thereafter, and as seen in FIG. 3 of the drawings, the inner shell 20 may 
be inserted in the partially completed outer shell, preferably, although 
not necessarily, after one of the end panels 60 is attached to the 
partially completed shell, with the inner shell 20 positioned in spaced 
relationship to opposing surfaces of the outer shell by means of spacer 
blocks 62 and 64 of foamed insulating material or the like. 
The other end panel 60 can then be attached to the top and bottom shell 
assemblies 36 and 46, respectively by means of self-tapping screws 66 as 
seen in FIG. 5 of the drawings, and to the back panel 54 in a similar 
manner as shown in FIG. 6 of the drawings. Crimped, interfitting 
connections, similar to those shown in FIG. 11 of the drawings, can be 
formed between the forward vertical edges of the panels 60 and the stiles 
30 and 32 as seen in FIG. 6 of the drawings. 
At this stage in the construction of the cabinet of the present invention 
the entire housing has been assembled as seen in FIG. 4 of the drawings, 
but the components of the outer shell are merely loosely interconnected 
and capable of relative movement between each other. At this point 
vertical and horizontal breaker strips 68 and 70, respectively, are 
positioned in grooves formed in the components of the main structural 
frame and the inner shell 20, as seen in FIGS. 6, 7, 8 and 10 of the 
drawings. Prior to inserting the breaker strips a heating coil 72 is 
inserted in the grooves formed in the structural members, as seen in FIG. 
8 of the drawings. 
The loosely yet positively connected assemblage of components is then 
placed in a jig 80 shown in FIGS. 12 through 15 of the drawings. The jig 
80 consists of a base 82 and side walls 84, 86, 88 and 90. The structure 
shown in FIG. 4 of the drawings is positioned in the jig with the back 
panel 54 laying on the base 82, the bottom shell assembly 46 positioned 
adjacent the side wall 88, the top shell assembly 36 positioned adjacent 
the wall 84 of the jig 80 and the side panels 60 positioned adjacent the 
walls 86 and 90 of the jig. A vertical mullion support 92 is then 
positioned within the cabinet behind the adjustable vertical mullion 34, 
as seen in FIG. 14 of the drawings, and adjusted to provide firm internal 
support for the mullion 34. 
The side walls of the jig are then raised to a position extending at right 
angles to the bottom wall 82 and fixed in this position. As this is 
accomplished the loosely connected components of the outer shell are 
racked so that the front and back, top and bottom and sides of the outer 
shell are squared with respect to each other and assume their desired 
final positions. 
Of course, internal support as shown at 94 in FIGS. 13 through 15 of the 
drawings, may be provided having linkage operated expandable portions so 
that they can be pressed outwardly and provide firm internal support for 
the inner shell. Such mechanisms can be of any convenient form and do not 
form per se part of the present invention. 
With the enclosure 12 locked within the jig 80 a hardenable insulating 
material in liquid form, such as polyurethane, is pumped into the 
insulating cavity 23, through a suitable opening 96 (FIG. 15) provided in 
the enlosure, with the insulating material foaming in situ and completely 
filling the insulating cavity as shown at 98 in FIGS. 13 through 15, and 
when hardened, fixing all of the components of the enclosure in their 
desired final positional relationship with respect to each other. 
Thus the present invention provides an insulated cabinet in which a main 
structural frame is utilized manufactured to precise tolerances and to 
which are attached the remaining components of the cabinet outer shell by 
mechanical connections which permit limited relative movement, and 
squaring of the enclosure is accomplished just prior to the final step in 
the manufacturing process through the use of a jig which temporarily fixes 
the components in their final desired positions until they can be 
permanently fixed in these positions by means of a hardened insulating 
material. 
While the method and article herein described constitute preferred 
embodiments of the invention, it is to be understood that the invention is 
not limited to this precise method and article, and that changes may be 
made therein without departing from the scope of the invention.