Insulated door
BACKGROUND OF THE INVENTION 
     This invention relates to insulated doors and, more particularly, to insulated doors having outer panels with folded sides. 
     Insulated doors for refrigerators, freezers of similar cabinets are typically formed from an outer panel of steel and an inner panel of plastic. The conventional method of construction has been to fold the four edges of the outer panel to form sides, screw the four edges of the inner panel to return flanges formed on these four edges, and pack the space between the inner and outer panels with insulating material. 
     Another insulated door is shown in U.S. Pat. No. 4,053,972. In this patent, the inner and outer panels together define a hollow enclosed chamber and into this chamber a foamed insulating material is placed, substantially filling the chamber and helping to interconnect the face and the drum. 
     However, a problem with conventional methods is that folding the four edges of the outer panel to form the four sides necessitates a press tool matching the size of the outer panel. Differences in the vertical dimension, even though the horizontal dimension might not vary, means that a special tool has to be provided for each size. This increases the cost of manufacture of the outer panel and hence of the insulated door. 
     SUMMARY OF THE INVENTION 
     The insulated door of the present invention has an outer panel with two sides formed by folding two opposing edges out of its four edges. Two end sections are provided which fit onto the other two opposing edges of the outer panel in such a way as to close off these two sides. An inner panel is disposed parallel to the outer panel so that its four edges are positioned inside the two folded sides and the two end sections. Insulation material is packed between the outer and inner panels. 
     The end sections include a first projecting rib and second projecting ribs which grip, from opposite sides in the thickness direction, the edges of the inner panel which are positioned inside the end sections either protruding or recessed interlocking parts are formed on the first or second ribs, and the corresponding other interlocking parts are formed on the ends of the inner panel. The inner panel and the two sections are joined by fitting together these protruding and recessed interlocking parts. 
     Thus, as long as one of the two dimensions (vertical/horizontal) is the same, the same tool can be used for forming the folded sides even though the other dimension may vary. Thus, the useful range of the tool is increased and the cost of manufacture reduced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a section of an insulated door of the present invention; 
     FIG. 2 is a section along the line II--II in FIG. 1; 
     FIG. 3 is an oblique detailed assembly drawing; and 
     FIG. 4 is an oblique enlarged plan of an end section with a section removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIGS. 1-3, outer panel 1, e.g. of colored sheet steel, as two opposing lengthwise edges folded by a press tool (not illustrated) into a shape having a &#34;C&#34; cross-section to form two sides 2. Each of sides 2 has a return flange 2a formed by folding the extreme edge inwards. End sections 3 and 4 are made of plastic, each being shaped like a long narrow rectangular trough open on one side. 
     As illustrated in FIG. 4, a first rib 5 is integrally molded along the inside length of each end section (from top to bottom in the drawing), while second ribs 6 are integrally molded, at intervals, a little above this first rib 5 in the drawing. Each of ribs 6 has a claw 7 projecting downwards in the drawing. 
     At each end of first rib 5 are extensions forming guide parts 5a with a bevelled face. Blind circular socket 8 is formed integrally in end sections 3 and 4 to take the hinge pins. 
     Plastic inner planel 9 has projecting part 9a to form pockets for bottles, etc. The four edges of inner panel 9 extend via a downward sloping section 10 to a flange 11. At two opposing edges, flange 11 is provided with an upward sloping section 13 forming a channel section 12 between it and downward sloping section 10. The extreme edge of upward sloping section 13 extends outwards to form a press-contact strip 14. 
     Engaging holes 15 (recessed interlocking parts) are formed, at intervals, on the edges of flange 11 on the lengthwise ends at positions corresponding to claws 7 of second ribs 6. Gasket 16 is fitted with an internal magnet 17, and has a hollow, integrally molded projected retaining part 20 with fins 18 and 19 at its tip. 
     An explanation follows of the steps in the assembly of an insulated door from the member constructed as described above. 
     First, end section 3 is fitted to one of the unfolded edges (i.e. the length direction in the exemplary embodiment) of outer panel 1, closing off the space between sides 2. Next, inner panel 9 is inserted from the as yet unclosed end of outer panel 1 along the length of outer panel 1. 
     Then flange 11 of the inserted end of inner panel 9 is placed on guides 5a of first rib 5 of end section 3 and pushed into end section 3. When this is done, the flange at this end is forced between first rib 5 and second ribs 6, and claws 7 of second ribs 6 snap into engagement with engaging holes 15 in flange 11. 
     Next, the end section 4 is fitted to the other edge (lengthwise direction in the exemplary embodiment) of outer panel 1, closing off the space between sides 2. 
     Then, in the same manner as already described, flange 11 at the other end is caught between the first and second ribs 5 and 6 of end section 4 so that outer panel 1, end sections 3 and 4 and inner panel 9 are all fastened together. In this assembled state, press-contact strip 14 of inner panel 9 is in contact over its whole length with return flanges 2a, which in turn face along channel sections 12 of inner panel 9 and partially close it off from the outside. Return flange 2a of outer panel 1 together with long channel section 12 of inner panel 9 define a retaining slot 21 in which the width of aperture 21a is narrower than the width of the bottom of slot 21. 
     Side walls 3a and 4a of end sections 3 and 4 face flange 11 at both ends of inner panel 9 with a controlled gap between them and flange 11. Thus, walls 3a and 4a of end sections 3 and 4 together with downward sloping section 10 and flange 11 of inner panel 9 define a retaining slot 22 in which the width of the aperture 22a is narrower than the width at the bottom of slot 22. Projection retaining part 20 of gasket 16 is pushed into retaining slots 21 and 22. When this is done, retaining fins 18 and 19 on projecting parts 20 make contact, in retaining slot 21 with downward sloping section 10 and return flange 2a, and, in retaining slot 22 with downward sloping section 10 and side walls 3a and 4a of end sections 3 and 4. As a result, gasket 16 is snapped into position along all four edges of inner panel 9. After gasket 16 has been fixed in this manner, the space between outer panel 1 and inner panel 9 is filled with insulating material 23 such as foamed urethane. 
     It will be appreciated by those skilled in the art that modifications within the scope of this invention are possible in the preferred exemplary embodiment described. For example, claws 7 may also be formed on first rib 5 or on inner panel 9 and engaging holes 15 may be formed on first rib 5 or on second ribs 6. In other respects also, this device is not limited to the embodiment described above, and variations may be effected provided there is no departure from the main principles of the device. 
     Since as the above explanation will have made clear only two opposing edges out of the four edges of the outer panel are folded to form sides, the size of the press tool to form the outer panel may be made to match the length of the longest side to be folded of the different outer panels being manufactured. Thus, the same press tool may be employed to fold many different outer panels as long as the unfolded dimension is the same. 
     Consequently, the useful range of the press tool can be increased, and the cost of manufacture of outer panels (and therefore of insulated doors) reduced. 
     Further, because two opposing edges of the inner panel are gripped between the first and second ribs, the inner panel can be held with a controlled gap between it and the outer panel, and this gap remains unaltered even when the inner panel is subjected to the foaming pressure of the insulating material. 
     Moreover, since either a protruding or recessed parts are formed on either the first or second ribs in the end sections, and the other of the two kinds of interlocking parts is formed on the inner panel, and the end sections and the inner panel are fastened together by the interlocking of the protruding and recessed parts, the outer panel, two end sections and inner panel are thus all fastened together. The outer panel, formed from colored steel, need not be subsequently painted. Unlike the case where holes to form the recessed interlocking parts are pierced in the outer panel and protruding interlocking parts formed in the end sections are made to engage in these holes, no necessity arises for rust-prevention treatment of such holes in the outer panel, and productivity is thereby improved. 
     While the article herein described constitutes preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise article, and that changes may be made therein without departing from the scope of the invention as defined by the following claims.