GB2096213A - Manhole cover - Google Patents

Abstract

A substantially airtight manhole cover (10) of pressed steel has a downturned lip (11), adjacent to which a depression (15) is formed allowing access from above, to an aperture (16) provided in the lip (11) for the insertion of a lifting tool (17). During manufacture the or each tool aperture (16) is formed in a blank of material at the same time as an adjacent short slit is made along the bending line of the lip (11); at the same time as the downturned lip (11) is formed by pressing along said bending line, the depression (15) is formed to expose the tool aperture (16), the slit edge (27) of the depression (15) then lying against the downturned lip (11) to preserve the air tightness of the cover (10) when in use. <IMAGE>

Description

SPECIFICATION Improved manhole cover The invention relates to manhole covers and more particularly to means for facilitating the lifting of manhole covers.

It is known to provide one or two slots in a manhole cover to enable a corresponding tool to be inserted and then turned to engage the underside of the cover, so that the cover can be lifted by the tool or tools. In the case of airtight manhole covers, a suitable piece of metal must be secured to the underside of the cover beneath the or each slot to prevent gas leakage through the slot. This involes an extra working operation.

A pressed metal manhole cover, according to the invention and having a downturned peripheral lip, also has at least one tool aperture in its downward lip and a depression adjacent this aperture, the material of the cover being slit along the bend line about which the respective lip portion is downwardly bent so that access from above to the aperture for inserting a suitable lifting tool can be had, the side of the slit on the edge of the depression lying against the lip portion to substantially preserve the air tightness.

The invention is further described, by way of example,with reference to the drawings, in which: Fig. 1 is a perspective view of a manhole cover according to the invention; Fig. 2 is a sectional detail, to a larger scale, through one of two lifting apertures and an adjacent depression; Fig. 3 is a fragmentary detail showing the depression and the lifting aperture; and Fig. 4 is a fragmentary view of the stamped blank from which the manhole cover is pressed.

Fig. 1 shows a pressed steel manhole cover 10 which is formed with a downturned peripheral lip 1 1. The lip 11 fits in a groove 12 (Fig. 2) of a manhole frame 13, adapted to be cemented to the top of a manhole in the usual manner. The cover 10 is formed with a conventional pattern of embossing 14 and with two depressions 1 5 which give access to tool slots 1 6 so that tools 1 7 can be inserted for lifting the manhole cover.

One depression 1 5 and tool slot 1 6 are shown more clearly in Figs. 2 and 3. To form these features of the cover, the stamped blank 18 (Fig. 4) from which the cover is pressed is given a slit 1 9 along the bend line 20a about which the portion 21 of the downturned lip 11 is subsequently bent to form the bend 20 (Fig. 3).

The aperture 1 6 and the slit 1 9 adjacent the aperture are formed during the stamping operation by which the blank 1 8 is stamped out of sheet steel. The depression 1 5 is formed during the subsequent pressing operation by which the four lip portions are bent down along the respective bend lines to form the peripheral lip 11.

The base of the depression 1 5 is pressed down below the tool slot 1 6 as shown in Fig. 2, the rim portion 22 of the depression having a downward bend 23 and an upward bend 24 so that the material between these bends is stretched to ensure that the edge 27 of the depression at one side of the slit 19 lies against the flange portion 21. This generally provides a sufficiently airtight seal without welding but the corners of the lip 11 will usually be welded to give added strength.

Finally the cover is galvanised in the usual manner, which then provides a complete seal between the edge 27 of the depression and the flange portion 21.

Thus it can be seen that tool apertures can be formed without any extra working operation to avoid sacrificing airtightness.

The tools 17 are formed from strip metal and each have a cranked end 25 adapted to fit in the aperture 16 and a curved handle 26. In place of slots 16, the tool apertures may be round holes in which case the tools would be made from round rod. Other shapes of tool apertures are possible.

1. A pressed steel manhole cover having a downturned peripheral lip, at least one tool aperture being provided in the downturned lip and a depression being formed in the cover adjacent to this tool aperture, the material of the cover being slit along the bend line about which the respective lip portion is downwardly bent so that the depression allows for access from above to the tool aperture, for the insertion of a suitable lifting tool, the side of the slit on the edge of the depression, lying against the lip to substantially preserve the air tightness of the cover when in use.

2. A pressed steel manhole cover as claimed in claim 1, in which the cover is generally rectangular in shape with two tool apertures being provided in the downturned lip, the tool apertures being located on opposite sides of the cover.

3. A pressed steel manhole cover as claimed in claim 1 or claim 2, in which the or each tool aperture is elongate in shape.

4. A pressed steel manhole cover as claimed in claim 1 or claim 2, in which the or each tool aperture is circular in shape.

5. A pressed steel manhole cover as claimed in claim 2, in which the cover is pressed from a sheet of metal, the adjacent sides of the downturned lip being welded together at corner regions of the cover.

6. A pressed steel manhole cover constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved manhole cover The invention relates to manhole covers and more particularly to means for facilitating the lifting of manhole covers. It is known to provide one or two slots in a manhole cover to enable a corresponding tool to be inserted and then turned to engage the underside of the cover, so that the cover can be lifted by the tool or tools. In the case of airtight manhole covers, a suitable piece of metal must be secured to the underside of the cover beneath the or each slot to prevent gas leakage through the slot. This involes an extra working operation. A pressed metal manhole cover, according to the invention and having a downturned peripheral lip, also has at least one tool aperture in its downward lip and a depression adjacent this aperture, the material of the cover being slit along the bend line about which the respective lip portion is downwardly bent so that access from above to the aperture for inserting a suitable lifting tool can be had, the side of the slit on the edge of the depression lying against the lip portion to substantially preserve the air tightness. The invention is further described, by way of example,with reference to the drawings, in which: Fig. 1 is a perspective view of a manhole cover according to the invention; Fig. 2 is a sectional detail, to a larger scale, through one of two lifting apertures and an adjacent depression; Fig. 3 is a fragmentary detail showing the depression and the lifting aperture; and Fig. 4 is a fragmentary view of the stamped blank from which the manhole cover is pressed. Fig. 1 shows a pressed steel manhole cover 10 which is formed with a downturned peripheral lip 1 1. The lip 11 fits in a groove 12 (Fig. 2) of a manhole frame 13, adapted to be cemented to the top of a manhole in the usual manner. The cover 10 is formed with a conventional pattern of embossing 14 and with two depressions 1 5 which give access to tool slots 1 6 so that tools 1 7 can be inserted for lifting the manhole cover. One depression 1 5 and tool slot 1 6 are shown more clearly in Figs. 2 and 3. To form these features of the cover, the stamped blank 18 (Fig. 4) from which the cover is pressed is given a slit 1 9 along the bend line 20a about which the portion 21 of the downturned lip 11 is subsequently bent to form the bend 20 (Fig. 3). The aperture 1 6 and the slit 1 9 adjacent the aperture are formed during the stamping operation by which the blank 1 8 is stamped out of sheet steel. The depression 1 5 is formed during the subsequent pressing operation by which the four lip portions are bent down along the respective bend lines to form the peripheral lip 11. The base of the depression 1 5 is pressed down below the tool slot 1 6 as shown in Fig. 2, the rim portion 22 of the depression having a downward bend 23 and an upward bend 24 so that the material between these bends is stretched to ensure that the edge 27 of the depression at one side of the slit 19 lies against the flange portion 21. This generally provides a sufficiently airtight seal without welding but the corners of the lip 11 will usually be welded to give added strength. Finally the cover is galvanised in the usual manner, which then provides a complete seal between the edge 27 of the depression and the flange portion 21. Thus it can be seen that tool apertures can be formed without any extra working operation to avoid sacrificing airtightness. The tools 17 are formed from strip metal and each have a cranked end 25 adapted to fit in the aperture 16 and a curved handle 26. In place of slots 16, the tool apertures may be round holes in which case the tools would be made from round rod. Other shapes of tool apertures are possible. CLAIMS

1. A pressed steel manhole cover having a downturned peripheral lip, at least one tool aperture being provided in the downturned lip and a depression being formed in the cover adjacent to this tool aperture, the material of the cover being slit along the bend line about which the respective lip portion is downwardly bent so that the depression allows for access from above to the tool aperture, for the insertion of a suitable lifting tool, the side of the slit on the edge of the depression, lying against the lip to substantially preserve the air tightness of the cover when in use.

2. A pressed steel manhole cover as claimed in claim 1, in which the cover is generally rectangular in shape with two tool apertures being provided in the downturned lip, the tool apertures being located on opposite sides of the cover.

3. A pressed steel manhole cover as claimed in claim 1 or claim 2, in which the or each tool aperture is elongate in shape.

4. A pressed steel manhole cover as claimed in claim 1 or claim 2, in which the or each tool aperture is circular in shape.

5. A pressed steel manhole cover as claimed in claim 2, in which the cover is pressed from a sheet of metal, the adjacent sides of the downturned lip being welded together at corner regions of the cover.

6. A pressed steel manhole cover constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.