GB2035703A

GB2035703A - Rack for accommodating circuit boards

Info

Publication number: GB2035703A
Application number: GB7938597A
Authority: GB
Original assignee: APW Electronics Ltd
Current assignee: APW Electronics Ltd
Priority date: 1978-11-08
Filing date: 1979-11-07
Publication date: 1980-06-18
Also published as: DE7833192U1; FR2441316A1

Abstract

A rack for accommodating circuit boards comprises metal end plates 10 joined by extruded metal tie bars 11, 12 carrying pairs of guide rails having slots engageable by the edges of the circuit boards. The end plates have rows of holes 17 at equal pitch into which screws 13 may be passed to locate the tie bars at different fore and aft positions in the rack. To prevent the tie bars from rocking locating mouldings 25, 33 are provided between the ends of the tie bars and the end plates. <IMAGE>

Description

SPECIFICATION Improved rack for accommodating circuit boards This invention is concerned with a rack for accommodating circuit boards of the type, hereinafter termed the type specified, comprising two metal end plates, pairs of upper and lower extruded metal tie bars which are fixed at their opposite ends to the end plates, and guide rails moulded from plastics material which extend between the upper tie bars and between the lower tie bars in directions parallel to the end plates in opposed pairs, the guide rails being attached at their ends to the tie bars and having grooves in their opposing faces for accommodating the upper and lower edges of circuit boards slid endwise into the rack.Such racks can also be used to accommodate modules carrying larger electrical components than a circuit board and having upper and lower rails which can be slid into the grooves in appropriate upper and lower guide rails.

It is sometimes desired that the tie bars should be adjustable in a fore and aft direction with respect to the end plates so that they may be spanned by guide rails appropriate for the accommodation of longer or shorter circuit boards. The invention enables this to be achieved without it being necessary to provide in the end plates more than upper and lower rows of regularly pitched holes for accommodation screws for retaining the upper and lowertie bars in alternative fore and aft positions with respect to the end plates. Screws inserted through these holes into tapped holes in the end plates would not locate the tie bars with sufficient accuracy or prevent them from rocking with respect to the end plates. Accord ingly location mouldings of plastics material are provided between the ends of the tie bars and the end plates.

In a rack of the type specified according to the invention, therefore, the end plates have rows of regularly spaced holes for accommodating screws for attaching the upper and lower tie bars to the end plates and the rack includes location mouldings of plastics material disposed between the ends of the tie bars and the end plates, each moulding having a throughgoing hole through which a screw is passed through a selected hole in the adjoining end plate into a tapped hole in the adjoining tie bar, a projection on its outer face which engages the hole in the end plate adjoining that through which the screw is passed, and a projection on its inner face which engages in a recess in the tie bar to prevent the tie bar from rocking in relation to the end plate.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a rack with the guide rails omitted, Figure 2 is a section on a larger scale on the line Il-Il in Figure 1, Figure 3 is an exploded view showing how a front tie bar is mounted in the rack, and Figure 4 is a similar view showing how the rear tie bar is mounted in the rack.

As shown in Figure 1, the rack consists of a pair of metal end plates 10, joined by a pair of opposed rear tie bars 11 and a pair of opposed front tie bars 12 which are extruded metal sections and are attached to the end plates by screws 13. The front and rear tie bars 12, 11 are spanned by opposed pairs of guide rails, shown in Figure 2, which are moulded from plastics material and are formed with slots in the opposing faces to enable circuit boards or modules to be slid into the rack.

As illustrated the rack may be divided by a divider plate 14 into sections for respectively accommodating wider and narrow circuit boards, in which case the section for the narrow boards includes a pair of intermediatefronttie bars 15, placed back to back and extending between one end plate and the divider plate, and a pair of intermediate rear tie bars 16 is provided between the two end plates.

The rack shown in the drawings permits of adjustment fore and aft of the tie bars and the end plates 10 accordingly have upper and lower rows of regularly pitched holes 17, 18 for respectively accommodating the fixing screws 13 of the upper and lower tie bars.

As shown in Figure 3, each front tie bar 12 has a series of regularly pitched slots 19 for accommodation of projections on the guide rails and a throughgoing hole 20 which is tapped at its ends to accommodate the fixing screws 13. Each rear tie bar 11, as shown in Figure 4, has a similar set of slots 21 for accommodating projections 22 on the guide rails 23 as illustrated in Figure 2. Each rear tie bar also has a throughgoing hole 24 which is tapped at its ends to receive the fixing screws 13.

The screws 13 alone would not be effective to prevent the tie bars from rocking with respect to the end plates. Accordingly locating mouldings 25 of plastics material are provided between the ends of each front tie bar 12 and the end plates 10. As shown in Figure 3, each moulding 25 has a hole 26 through which a fixing screw 13 may pass through a selected hole 17 in the end plate into the hole 20 in the tie bar.

It has on its outer face projections 27 which engage and locate the moulding in the holes 17 on opposite sides of the hole engaged by the screw 13. Each moulding has on its inner face projections 28,29 and 30. The projections 28 and 29 fit into a T slot 31 in the tie bar and the projection 30 hooks under the portion 32 of the tie bar in which the slots 19 are formed.

Similar mouldings 33, but of different shape, are provided between the ends of the rear tie bars 11.

Each moulding 33 has a hole 34to accommodate a fixing screw 13 and two projections 35 on its outer face to engage the holes 17 in the end plate on opposite sides of that engaged by the screw 13. Each moulding 33 has on its inner face two projections 36, 37. The projection 36 fits into a slot 38 in the tie bar and the projection 37 fits into another slot 39 in the tie bar.

Similar locating mouldings 40 are provided between the ends of the front intermediate tie bars 15 and the divider plate 14 and end wall 10, and other similar locating mouldings 41 are provided between the ends of the rear intermediate tie bars 16 and the end plates 10.

Claims

1. A rack of the type specified, wherein the end plates have rows of regularly spaced holes for accommodating screws for attaching the upper and lower tie bars to the end plates and which includes location mouldings of plastics material disposed between the ends of the tie bars and the end plates, each moulding having a throughgoing hole through which a screw is passed through a selected hole in the adjoining end plate into a tapped hole in the adjoining tie bar, a projection on its outer face which engages the hole in the end plate adjoining that through which the screw is passed, and a projection on its inner face which engages in a recess in the tie barto prevent the tie bar from rocking in relation to the end place.

2. A rack according to claim 1, in which each moulding has on its outer face two projections which engage in holes in the rack on opposite sides of the hole engaged by the screw.

3. A rack according to claim 1, substantially as described herein with reference to the accompanying drawings.