Card cage for printed circuit cards

[57] ABSTRACT

A card cage for printed circuit cards in which flexible plastic elements mounted in a metal frame securely but yieldably hold printed circuit cards in place.

Claims, 4 Drawing Figures

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PATENTE0MAY231872

3,664,510

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<img file="US3664510A_D0003.tif" />

ATTORNEY

3,664,510

CARD CAGE FOR PRINTED CIRCUIT CARDS

This invention relates to mounting means for supporting printed circuit cards in a cabinet or enclosure.

Such mounting means are commonly referred to as card cages since generally they resemble cages and are of a unitary construction of varying sizes to accomodate various numbers and sizes of printed circuit cards or boards on which are mounted the usual electronic components including integrated circuit elements. The card cages are mounted and secured to a framework on which the terminal plugs and harness wiring are also mounted. The arrangement is such that when the selected printed circuit cards are slipped into their proper positions in the card cage a completely wired electrical apparatus is produced.

The object of the present invention is to provide an improved card cage that securely holds a printed circuit card therein, yet permits a circuit card to be readily removed when so desired. It is a further object of the invention to provide a simpler, cheaper, and more easily manufactured card cage than had previously been provided.

In carrying out the invention there is provided a card cage having spaced apart top and bottom members with aligned apertures into which flexible card guides are snapped. The card guides are separately formed, preferably of a plastic material and they are snapped into place after the top and bottom members are assembled into a box-like frame of desired size.

A preferred embodiment of the invention is disclosed in the accompanying drawing and the following specification.

In the drawing:

FIG. 1 is a perspective view of a card cage according to the present invention, but showing only a small number of card guides;

FIG. 2 is a sectional view taken along line 2—2 of FIG. 1;

FIG. 3 is an enlarged detail view in side elevation of a card guide in position in the card cage; and

FIG. 4 is an enlarged perspective view of a card guide showing its details.

Referring now to FIG. 1 of the drawing, it will be observed that the card cage 10 comprises principally an upper frame member 11, a lower frame member 12, and a pair of side pieces 13 and 14 which hold members 11 and 12 in spaced apart relationship to form an open box-like structure. The frame members and the side pieces may be formed of sheet metal and spot welded one to another, after which the structure may be zinc coated to inhibit corrosion.

The side pieces 13 and 14 are identical and each consists of essentially a flat sheet having a flange 15 bent at a 90° angle to the surface of the sheet. The flange 15 is provided with a pair of slots 16 and 17 which permit the card cage, after assembly, to be bolted to a cabinet frame. The frame generally will be formed of aluminum extrusions.

The upper frame member 11 and the lower frame member 12 likewise are identical in the preferred embodiment so that only one member need be described. The bottom frame member comprises an elongated sheet the forward edge 20 of which is bent several times along paralled longitudinal lines to form a U-shaped cross section which will give rigidity to the completed structure. The rear edge 21 of the sheet is similarly bent at right angles to the sheet surface and two tabs 22, originally provided in the sheet stamping, are also bent at right angles to the sheet surface as well as to the rear edge. Two flaps 23, one at each end of member 12, are bent at right angles to the sheet surface, and when so formed each one lies in the same plane as an associated tab 22. The upper frame member 11 is similarly formed and it is to the flaps 24 and tabs 25 that the side pieces 13 and 14 are spot welded.

It will be observed that the surfaces of members 11 and 12 are each perforated with a series of apertures 26 spaced longitudinally along the length of the member. Whether the apertures are provided before or after the member is bent to shape is immaterial and whichever procedure is most practical can be followed. Each transverse row of apertures in the bottom member 12 will be in line with a similar row of apertures in the upper member, and when the card holders 27 are placed in the apertures as hereinafter described, a printed circuit card can be mounted in position as determined by the aperture positions. Of course, members 11 and 12 can be of any desired length so as to accomodate any number of cards.

There will be four apertures 26 in any transverse row thereof, a front pair 30 and a rear pair 31. The spacing between the innermost aperture of each pair of apertures is not critical, and in fact will vary for different card cages that are fabricated to hold different size printed circuit cards. However, the spacing between each aperture of a pair of apertures is critical in the sense to be hereinafter made clear. For the time being it will suffice to say that the apertures in each pair of apertures are spaced apart a fixed distance.

For each pair of transversely spaced apertures in upper member 11 and lower member 12 a card holder 27 is provided. The card holder is molded from a plastic material and is formed with two separated guide elements 32 joined by a flexible strip 33. The guide elements 32, due to their physical shape, are essentially firm and retain their shape even though the material from which they are molded is such that connecting strip 33 is flexible and resilient. Guide elements 32 are formed with an open channel 34 into which the edge of a printed circuit card can fit snugly. V-grooves 35 at the forward end of channel 34 facilitate the insertion of a circuit card into the card cage. By providing a V-groove at each end of channel 34 it does not matter if holder 27 is reversed when snapped into a pair of apertures 26.

Under each guide element 32 of a card holder 27 there is a projecting member 36 having the general shape of two truncated cones formed base to base. The base of the cone, or in other words the greatest diameter of the projecting member will be slightly greater than the diameter of an aperture 26. The diameter of the projecting member where it is joined to guide element 32 will be less than but about the diameter of aperture 26. The spacing between the two projecting members of a card holder 27 will be slightly greater than the spacing between the two apertures of an aperture pair. (See FIG. 4) It is in this sense that the spacing between apertures is critical as the term was used before. Because of the resiliency of the materials used to form a card holder 27 the projecting members 36 can be pushed through apertures and held firmly in place. Also because of the flexibility of strip 33 and the differences in the spacings between the projecting members 36 and between the apertures 26 strip 33 will bow upwardly. If because of the large openings 42 provided to lighten the weight of the structure, strip 33 bows downwardly, it can be manually pushed upwardly. The dimensions of the various spacings are such that strip 33 bows above a line joining the bottoms of the channels 34 formed in the guide elements of a card holder. In this way, when a card cage is fully assembled with card holders and a printed circuit card is inserted, the card will be resiliently held by the bowed strips of four card holders (See FIG. 4).

In use, a card cage will be assembled as shown in FIG. 1 and a card holder 27 inserted in each pair of apertures. Thus in each transverse section of the card cage there will be four card holders to hold a printed circuit card, two in upper member 11 and two in lower member 12. When the card cage is mounted in its cabinet and the terminal plugs connected to the frame by means of mounting holes 41 and wiring harness connected, a printed circuit card 37 can be inserted into the cage as shown in FIG- 1, and it will be securely, although resiliently, held by the bowed strips 33 of the card holders. A stop 40 can be provided to limit the distance a card can be pushed into the cage.