GB2148362A - An access cover and frame assembly - Google Patents

Abstract

An access cover and the frame in which it seats are both formed from a plurality of pressed or rolled metal angle sections joined together at its corners. Each frame section (12) has a substantially horizontal flange (13) with two troughs (15, 16) extending over the length of the section pressed therein and an upwardly extending flange (14) at the outer edge of the horizontal flange. The cover is of the type arranged to receive an infill and is insertable in the frame so as to make sealing contact with sealing material in troughs of the frame. Each cover section has a horizontal flange (20) and an upwardly extending flange (21). The horizontal flange has two downwards projections (22, 23) pressed therein and adapted to fit in respective troughs in the frame to provide a double seal cover and frame assembly for an infill type cover. Instead of pressing, the metal angle sections could be rolled, and in this case the frame and cover could each be formed of a single section folded and then welded at its two ends. <IMAGE>

Description

SPECIFICATION An access cover and frame assembly This invention relates to an access cover and frame assembly and more particularly to a load bearing access cover and frame assembly for an inspection hole e.g. a sewage manhole in a pedestrian or road traffic bearing surface.

According to the invention there is provided an access cover and frame assembly, wherein the frame comprises one or more cold formed metal sections, the or each section having a substantially horizontal flange with two parallel spaced troughs extending over the length of the section and an upwardly extending flange at or adjacent to the outer edge of the horizontal flange, and wherein the cover also comprises one or more cold formed metal sections, the or each cover section having a substantially horizontal flange with two parallel spaced downwards projections extending over the length of the cover section and an upwardly extending flange at the outer edge of the horizontal flange, the cover being for receiving an infill and being insertable in the frame when downwards projections of the cover are located in respective troughs of the frame.

The or each frame section and the or each cover section may be cold pressed or cold rolled.

In practice the troughs of the frame may contain sealing material such as elastomeric material, grease or sand. The two troughs of each frame section may contain the same or different sealing material.

Preferably, the troughs and/or projections when viewed in cross-section are curved. Advantageously, the mean width of each projection when viewed in cross-section is less than the mean width of each trough when viewed in cross-section and the uppermost portion of the ridge between the two troughs is below the plane of its respective flange in order to give flexibility of position of the cover in the frame to allow for manufacturing tolerances.

The upwardly extending flanges of the frame and cover may be substantially vertical or may be inclined to the vertical. When vertical the upper portion of each vertical flange of the cover is advantageously offset outwardly of its respective lower portion to prevent the cover becoming jammed in the frame due to dirt.

The cover may have a solid base or reinforcing bars for retaining the desired infill.

Each frame may be adapted to receive two or more covers side by side.

The terms 'horizontal' and 'vertical' are used herein in relation to the cover and frame assembly on the basis that the cover and frame are laid down flat on a horizontal surface. It is however to be understood that the assembly need not necessarily cover a hole in a horizontal surface.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of one embodiment of an access cover and frame assembly according to the invention; Figure 2 is a cross-section through a section of the frame; Figure 3 is a cross-section through a section of the cover; and Figure 4 shows in cross-section the cover section of Figure 3 mounted on the frame section of Figure 2.

Referring to the drawings, the access cover 10 shown therein is in the form of a recessed manhole cover adapted to receive an infill such as of concrete, tiles, asphalt, soil or grass. The cover is insertable in the frame 11 and the cover 10 and frame 11 are rectangular when viewed in plan.

The frame 11 comprises four elongate sections 12 cold pressed from mild steel plate or strip, mitred and welded together at the corners of the frame. Each frame section comprises a horizontal flange 13 and a vertical flange 14 integral with and upstanding from the outer edge of the horizontal flange 13. The horizontal flange 13 has two parallel spaced apart elongate troughs 15 and 16 pressed therein. The troughs 15 and 16 extend over the entire length of the section 12 and communicate with respective troughs in adjoining sections of the frame. When viewed in cross-section the troughs 15 and 16 are curved and indeed together with a ridge 17 between them define a generally sinusoidal profile but with the crest of the ridge 17 below the general plane of the horizontal flange 13 for a reason explained hereafter.The troughs are formed in the flange 13 intermediate its inner and outer edges so that the flange has horizontally extending portions on either side of the trough formation. The sections 12 are formed by pressing from mild steel plate or strip which may be, for example, 2 or 3 mm in thickness. Each section 12 may be formed in a single pressing operation or alternatively the troughs 15 and 16 can be pressed in one operation and the angle between the flanges 13, 14 in another operation.

The cover 10 also comprises four elongate sections 18 cold pressed from mild steel plate or strip, mitred and welded together at the corners of the cover and a base plate 19 welded to the sections 18. The base plate 19 could however be replaced by reinforcing bars. Each cover section 18 comprises a horizontal flange 20 and a vertical flange 21 integral with and upstanding from the outer edge of the horizontal flange 20. The horizontal flange has two parallel spaced apart elongate depending projections 22 and 23 pressed therein. The projections 22 and 23 extend over the entire length of the section 18 and connect with respective projections in adjoining sections of the cover.

When viewed in cross-section the projections 22 and 23 are curved. However, the lower region of each projection 22, 23 is more sharply curved that the corresponding lower region of each trough 15 and 16 and the mean width of each projection 22, 23 is less than the mean width of each trough 15, 16. However, the lateral spacing between the lowermost portions of the two projections 22, 23 is intended, ignoring manufacturing tolerances, to be equal to the lateral spacing between the lowermost portions of the two troughs 15, 16 in each of the frame sections 12. The portion 24 of the horizontal flange 20 between the projections 22 and 23 is more gently curved than the corresponding portion or ridge 17 between the troughs 15 and 16 and the portion 24 in its uppermost region lies in the general plane of the flange 20.The projections 22 and 23 are formed in the flange 20 intermediate its inner and outer edges so that the flange 20 has horizontally extending portions on either side of the projection combination. The vertical flange 21 has its upper portion outwardly offset of its respective lower portion so as to prevent dirt from causing the cover to jam in the frame. The sections 18 are formed by pressing from mild steel plate or strip which may be, for example, 2 or 3 mm in thickness. Each section 18 may be formed in a single pressing operation or alternatively the projections 22 and 23 can be pressed in one operation, the angle between the flanges 20 and 21 in another operation and indeed perhaps the offsetting of the upper and lower portions of the vertical flange 21 in yet another operation.

The troughs 15 and 16 in the frame sections may receive sealing material such as resilient seals of elastomeric material e.g. neoprene, or grease or sand. The two troughs 15 and 16 may contain the same sealing material or different sealing materials. Figure 4 shows a cover section 18 mounted in a frame section 12 and it will be seen that the projections 22 and 23 are received in the troughs 15 and 16 respectively. Owing to the projections 22 and 23 being of smaller mean width than the troughs 15 and 16 and to the spacing between the crest of the ridge 17 and portion 22 created by arranging the crest of the ridge to be below the general plane of the horizontal flange 13 there is a limited degree of flexibility of position of the cover in the frame to allow for manufacturing tolerances.

Releasable fastening devices may be provided for securing the cover to the frame in which case these will be located preferably at the corners of the cover and frame.

The cover and frame may be provided with a protective coating both before and after forming or only after forming.

Instead of cold pressing the sections 12 and 18 from mild steel it is conceivable that they could be pressed from ductile iron.

The frame sections 12 and cover sections 18 could be cold rolled in mild steel or ductile iron, instead of being cold pressed. When rolling the frame and cover sections will be made in long lengths. These lengths can be cut to size mitred and welded together at the corners of the frame and the cover. Alternatively, they can be folded and welded at their two ends to form each of the frame and cover surround from a single section.

Claims (14)

1. An access cover and frame assembly, wherein the frame comprises one or more cold formed metal sections, the or each section having a substantially horizontal flange with two parallel spaced troughs extending over the length of the section and an upwardly extending flange at or adjacent to the outer edge of the horizontal flange, and wherein the cover also comprises one or more cold formed metal sections, the or each cover section having a substantially horizontal flange with two parallel spaced downwards projections extending over the length of the cover section and an upwardly extending flange at the outer edge of the horizontal flange, the cover being for receiving an infill and being insertable in the frame when downwards projections of the cover are located in respective troughs of the frame.

2. The assembly of Claim 1, wherein at least the troughs or the projections when viewed in cross-section are curved.

3. The assembly of Claim 2, wherein the troughs and the projections when viewed in crosssection are curved.

4. The assembly of any one of Claims 1-3, wherein the mean width of each projection when viewed in cross-section is less than the mean width of each trough when viewed in cross-section.

5. The assembly of Claim 4, wherein the uppermost portion of the ridge between the two troughs is below the plane of its respective flange.

6. The assembly of any one of the preceding claims, wherein the upwardly extending flanges of the frame and cover are substantially vertical.

7. The assembly of Claim 6, wherein the upper portion of each vertical flange of the cover is offset outwardly of its respective lower portion.

8. The assembly of any one of Claims 1-4, wherein the upwardly extending flanges of the frame and the cover are inclined to the vertical.

9. The assembly of any one of the preceding claims, wherein the cover has a solid base for retaining an infill.

10. The assembly of any one of Claims 1-8, wherein the cover has reinforcing bars.

11. The assembly of any one of the preceding claims, wherein the frame is for receiving two or more covers side by side.

12. The assembly of any one of the preceding claims, wherein the frame and/or cover sections are cold pressed.

13. The assembly of any one of Claims 1-11, wherein the frame and/or cover sections are cold rolled.

14. An access cover and frame assembly, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.