GB2222487A

GB2222487A - A cabinet for electronic equipment

Info

Publication number: GB2222487A
Application number: GB8918195A
Authority: GB
Inventors: Wlliam David Hindley
Original assignee: Telent Technologies Services Ltd; Plessey Telecommunications Ltd
Current assignee: Telent Technologies Services Ltd; Plessey Telecommunications Ltd
Priority date: 1988-09-06
Filing date: 1989-08-09
Publication date: 1990-03-07
Also published as: GB8918195D0; GB8820870D0

Abstract

The invention concerns a method of manufacturing a cabinet for housing electronic equipment and providing protection against EMI. At least the top (11), bottom and side walls (12) of the cabinet are formed with castellations and the cabinet is assembled by force fitting the castellations together. This method of assembly avoids the use of screws to hold the walls together. <IMAGE>

Description

A CABINET FOR ELECTRONIC EQUIPMENT.

The present invention concerns cabinets or shelf units for providing protection to internal equipment from Electromagnetic Interference (EMI) and also for preventing leakage of EMI from the equipment housed within the unit.

An important feature in the construction of such units is that there should be the closest possible electrical contact between the various walls of the unit. Previously this contact has been achieved by screwing the edges of the walls of the unit. The higher the frequency to be tolerated the greater the number of screws per unit length. Thus for units intended to protect equipment from EMI of up to 2 Megabits frequency or to prevent leakage of EMI from the unit up to the same frequency a screw every two inches is necessary. At a 100 megabits a screw every t inch is required.

This method of manufacture is both expensive and time consuming and an object of the present invention is to enable the production of EMI proof cabinets in a simpler and less expensive manner.

Accordingly from one aspect the invention consists in a method of manufacturing a cabinet for housing electronic equipment and providing protection against EMI forming at least the bottom and side walls of the cabinet with castellations, and force fitting the top, bottom and side walls together.

Preferably at least some of the walls having interlocking castellations are curved prior to assembly.

In accordance with a feature of the Invention rivetting notches may be formed in some or all of the castellations to improve electrical contact.

in order that the invention may be more readily understood, an embodiment thereof together with several possible variants will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a cabinet according to the present invention.

Figure 2 shows one aspect of the manufacture of the cabinet of Figure 1, Figure 3 shows possible modifications in structure, and Figure 4 is a cross-section through the cabinet of Figure 1 showing another type of assembly technique.

Referring now to the drawings Figure 1 shows a cabinet for protecting equipment, and in particular telecorrrjnications equipment from EMI and for preventing leakage of EMI.

The cabinet is essentially made from a number of sheets of conducting metal and a front cover 10 which is a thermoplastics injection moulding. The cabinet has an upper cover 11 which is perforated to allow cooling and which is secured to two similar side plates 12 by interlocking castellations.

These can be seen in Figure 2 from which figure it can be seen that the top and side plates, prior to assembley, both include deliberate curves to ensure that after assembley the interlocking castellations make the best possible electrical contact.

Figure 3 of the drawings shows a number of options in the basic interlocking arrangement shown in Figure 1.

Thus Option 1 corresponds to the arrangement shown in Figure 1. Option 2 shows a variant in which the castellations are dovetailed. Option 3 shows that the electrical contact between the castellations can be improved by providing rivetting knotches 20 in the castellations. The formation of these notches forces the side of the castellations outwardly into even closer contact with the abutting edges. Finally Option 4 shows a mortice and tenon type of structure which may also include the rivetting feature shown in Option 3.

The side covers 12 are also screwed at 15 to cross embers 16. The cross members 16 are U-shaped in section as can best be seen in Figure 4. The bores into which the screws are inserted are formed by punching-in small sections 17 of the cross-members and then using self-tapping screws. This procedure means that the cross-members 16 can be cut to length rather than having end plates formed on the cross-members by bending.

Claims

1. A method of manufacturing a cabinet for housing electronic equipment and providing protection against EMI, comprising forming the side walls of the cabinet with castellations at their upper and lower edges, forming corresponding castellations on the top and bottom walls of the cabinet, all the walls being of conductive metal, and force fitting the top, bottom and side walls together.

2. A method as claimed in Claim 1, wherein at least some of the walls having interlocking castellations are curved prior to assembley.

3. A method as claimed in Claim 1 or Claim 2 wherein rivetting notches are formed in some or all of said castellations to improve electrical contact.

4. A method as claimed in any one of the preceding claims wherein the side walls are screwed to cross-members which are U-shaped in cross-section, the screws being self-tapping and being screwed into sections of said cross-members which have been punched in.

5. A method of manufacturing a cabinet for housing electronic equipment and providing protection against EMI substantially as hereinbefore described with reference to the accompanying drawings.

6. A cabinet for housing electronic equipment and providing protection against EMI and manufactured by the method as claimed in any one of the preceding claims.