GB2616297A

GB2616297A - Cover

Info

Publication number: GB2616297A
Application number: GB2202978.9A
Authority: GB
Inventors: Francis Clark Ronald
Original assignee: CLARKSTEEL HOLDINGS Ltd
Current assignee: CLARKSTEEL HOLDINGS Ltd
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-09-06
Also published as: GB202202978D0

Abstract

A metal manhole cover tray comprising a plurality of peripheral walls 102a-d surrounding a floor panel 103 to provide a space for receiving a finishing substrate. The plurality of peripheral walls comprises a first peripheral wall and a second peripheral wall. The first peripheral wall 102a comprises a main portion extending upwardly from the floor panel and adjoining the second peripheral wall along a corner edge thereby defining a corner of the tray, the first peripheral wall further comprising a tab portion 105 having been bent to overlap and contact with the second peripheral wall 102b. The tab portion and second peripheral wall each comprise a region of mutual deformation conforming to one another thereby forming a press-joint between the tab portion and second peripheral wall. The tray may comprise a drainage hole 109.

Description

Field of Invention

The present invention relates to a closure for closing an opening in the ground, particularly, removable covers for closing a manhole, drain, or other in-ground inspection chamber.

Background

Drains, manholes, inspection chambers, maintenance holes, and the like require covering to prevent materials or unauthorised persons from accessing or falling into the drain, manhole etc. Typically, this is achieved using a cover acting as a removable lid that sits on top of an opening to the drain, manhole etc. The opening is normally large enough for a person to pass through once the cover is removed. Such openings are often embedded in a road surface and must withstand loads caused by pedestrian footfall and/or vehicular traffic. Therefore, covers for such openings are designed to withstand these loads. Existing covers can be manufactured using steel and sometimes take the form of a tray that sits within a frame at the opening to the drain, manhole cover etc. The tray can be filled with a finishing substrate which provides a material corresponding to the surrounding surface material, such as paving blocks, bricks, tarmac, or concrete for example. As such, the cover blends in to the surrounding ground surface both aesthetically and in respect of the surface texture. Some covers include lifting handles that remain exposed after the tray has been filled with material. The lifting handles enable a user to open the cover, often via use of separate hooks, to access the drain or manhole.

Typically, the tray of a cover is manufactured by welding sheets of metal together. There exists a need to provide an improved cover and method of manufacturing a cover.

Summary of Invention

According to a first aspect there is provided a metal manhole cover tray comprising a plurality of peripheral walls surrounding a floor panel to provide a space for receiving a finishing substrate. The plurality of peripheral walls comprises a first peripheral wall and a second peripheral wall. The first peripheral wall comprises a main portion extending upwardly from the floor panel and adjoining the second peripheral wall along a corner edge thereby defining a corner of the tray, the first peripheral wall further comprising a tab portion having been bent to overlap and contact with the second peripheral wall.

The tab portion and second peripheral wall each comprise a region of mutual deformation conforming to one another thereby forming a press-joint between the tab portion and second peripheral wall.

The use of bending and a press-joint as discussed herein provides for a manhole cover tray to be manufactured without requiring the use of welding, thereby enabling a quicker, simpler and more environmentally-friendly manufacturing process. The use of a press-joint has been found to provide a connection between the peripheral walls to sufficiently maintain structural rigidity of the manhole tray under use, e.g. when filled with a finishing substrate and placed to cover a manhole in the ground.

Advantageously, the tab portions are not required to be a precise shape for enabling the press-joint, and manufacturing tolerances for the shapes of the peripheral walls and tab portions are relatively low, further enabling ease of manufacture and reduced costs of manufacture.

Optionally, the press-joint is circular.

Optionally, the circular press-joint has a diameter from 40 mm to 60 mm, and is preferably 50 mm.

Optionally, the tab portion is a first tab portion, and wherein the first peripheral wall further comprises a second tab portion being bent about the corner edge to be substantially planar with the first tab portion, the second tab portion being joined to the second peripheral wall by an additional press-joint between the second tab portion and the second peripheral wall.

Optionally, the first and second peripheral walls are at right angles to one another.

Optionally, the floor panel defines a plane and the defined corner of the tray is inclined with respect to the normal of the plane.

Optionally, the corner extends at an angle of less than 2 degrees away from the normal of the plane.

Optionally, the corner of the tray is angled away from the normal of the plane and away from the floor panel.

Optionally, the peripheral walls and floor panel are formed from an integral blank, the peripheral walls being defined by bending corresponding wall portions of the integral blank upwardly.

Optionally, the manhole cover further comprises a drainage aperture in between the first peripheral wall and second peripheral wall.

Optionally, the drainage aperture is formed from a notch in the floor panel.

Optionally, the floor panel comprises four sides, each side being integral to a corresponding peripheral wall.

Optionally, the tab portion is located outside of the space.

Optionally, the tab portion is located inside of the space.

According to a second aspect there is provided a method of manufacturing a manhole cover tray according to any preceding claim, the method comprising the steps of: obtaining a manhole cover tray blank comprising the floor panel, the first peripheral wall, and the second peripheral wall, wherein the peripheral walls are initially in a planar configuration; a tab bending step comprising bending the tab portion of the first peripheral wall to extend substantially perpendicular to the main portion of the first peripheral wall; a first wall bending step comprising bending the first peripheral wall of the blank to extend outwardly from the floor panel; a second wall bending step comprising bending the second peripheral wall of the blank to extend outwardly from the floor panel; the tab portion and peripheral walls being bent such that the tab portion overlaps the second peripheral wall; and forming a press-joint between the tab portion and second peripheral wall resulting in a region of mutual deformation conforming the tab portion and second peripheral wall to one another.

Optionally, the tab bending step takes place before the first and second wall bending steps.

Optionally, the step of forming the press-joint comprises compressing the tab portion and second peripheral wall together using a cylindrical punch.

Optionally, the step of obtaining comprises stamping or cutting the blank from a metal sheet.

Brief description of Figures

Figure 1 shows a top plan view of a blank for producing a manhole cover tray.

Figure 2 shows a perspective view of a manhole cover tray produced from the blank of Fig. 1, including an exploded view of optional additional features.

Figure 3a shows a close-up perspective view of a bended tab portion of a manhole cover tray produced from the blank of Fig. 1.

Figure 3b shows a close-up perspective view of a bended tab portion of a manhole tray cover produced from a blank having alternative geometry to the blank of Fig. 1.

Figure 4 shows a side-view of a manhole tray cover according to Fig. 2, with some features hidden from view being represented by dashed lines.

Figure 5 shows a perspective view of a manhole cover tray produced from an alternative blank to that of Fig. 1, including an exploded view of optional additional features.

Figure 6 shows a close-up perspective view of a region "S" of Fig. 5.

Figure 7 shows a top plan view of an alternative blank for producing a manhole cover tray.

Figure 8 shows a perspective view of a manhole cover tray produced from the blank of Fig. 7.

Figure 9 shows a close-up view of a press-fit joint incorporated into the manhole tray cover of Fig. 1.

Detailed Description

With reference to Figure 1, a blank 101 for forming a tray for use as a manhole/drain cover (referred to throughout as a manhole cover tray) comprises peripheral walls 102a, 102b, 102c, and 102d. The example of Fig. 1 shows four peripheral walls 102a-d, however there may be fewer or greater than four peripheral walls. The peripheral walls 102a-d surround a floor panel 103. In the example of Fig. 1 the floor panel 103 is rectangular, however the floor panel 103 may be square or another shape. Each peripheral wall 102a, 102b, 102c, and 102d includes a main portion 104 and at least one tab portion 105. Typically, the tab portion 105 is located at a corner edge 106 of the peripheral wall. The term "corner edge" used herein refers to an edge of the peripheral wall 102a-d which conforms to, or forms, an upstanding edge of the tray after assembly. As used herein, the term "upstanding" refers to a direction outwards or inwards of a plane corresponding to the plane of the floor panel 103 as represented in Fig. 1, but not necessarily normal to said plane of the floor panel 103. In the example of Fig. 1, two peripheral walls 102a, 102c, opposing one another across the rectangular floor panel 103, comprise tab portions proximal each end of the peripheral wall. As shown in Fig. 1, the tab portions 105 may be partially set inwards of the corner edges 106. Some peripherals walls may not comprise a tab portion. For example, in the example of Fig. 1, further two peripheral walls 102b and 102d do not comprise any tab portion (i.e. peripheral walls 102b and 102d solely comprise a main portion). The tab portions may comprise any shape that enables joining between a planar surface of the tab portion 105 and a main portion of an adjacent wall 102b, 102d, after bending of the tab portions and wall portions as discussed below.

The floor panel 103 comprises a planar sheet which defines a plane out of which the peripheral walls 102a-d extend to define the internal space of the tray. The internal space can be considered to be enclosed or partially enclosed by the peripheral walls 102a-d. In some examples (not shown in Figure 1), the floor panel 103 may comprise one or more strengthening features such as ribs or folds.

To form the manhole cover tray, there is a tab bending step and a wall bending step. Either step may be undertaken before the other, but preferably the tab bending step takes place before the wall bending step. During the tab bending step, the tab portions 105 are folded along tab folding lines 107. Where the tab bending step takes place before the wall bending step, the tab portions 105 may be bent out of the plane of the floor panel 103 (i.e. towards or away from the viewer from the viewpoint of Fig. 1). During the wall bending step, the peripheral walls 102a, 102b, 102c, 102d are bent out of the plane of the floor panel 103 (i.e. towards or away from the viewer from the viewpoint of Fig. 1) in the same direction as the tab portions and along wall folding lines 108. With reference to Fig. 1, the bending steps described above cause the tab portions 105 to overlap and make contact with contact a respective adjacent peripheral wall, such that a planar surface of each tab portion contacts a planar surface of the adjacent peripheral wall. For example, tab portions 105 of peripheral walls 101a and 102c overlap and contact peripheral walls 102b and 102d.

After the bending steps are complete, the peripheral walls 102a-d enclose the floor panel 103 so as to define an interior space in which a finishing substrate may be located and retained. Corner edges 106 of adjacent peripheral walls 102a-d become aligned to each other.

Subsequent to the bending steps, a press-joint is formed to join each tab portion 105 with a corresponding peripheral wall 102a-b that said tab portion 105 is overlapping. The press-joint is typically created by compressing the relevant tab portion 105 and corresponding adjacent peripheral wall 102b, 102d together using a punch. This results in a region of mutual deformation conforming the tab portion 105 and peripheral wall 102b, 102d to one another. In other words, there is a plastic deformation of the tab portion 105 and adjacent peripheral wall together to form an interlocked joint. Preferably the punch is a cylindrical punch. Such cylindrical punch may have a diameter of 40 to 60 mm, or, 50 mm. Before the formation of the press-joint, the tab portion 105 and peripheral wall to be joined to the tab portion 105 may be "stacked" one on top of another on a die, before being compressed with the punch. The procedure of forming the press-joint may be referred to as clinching or press-joining.

Typically, metals such as steel are utilised for the blank because they are sufficiently ductile to remain in place and not spring back after bending. As an example, the blank may be formed from a bendable steel metal sheet having a thickness in the region of 1.5 to 6 mm. The steel may be galvanised steel. The described bending process can be undertaken by a metal bending machine advantageously without the use of screws, rivets, or other fastening hardware or joining methods such as welding. The blank may be obtained by cutting or stamping the shape of the blank from a metal sheet.

With continued reference to Fig. 1, the base of the corner edges may be provided with a notch 109 from which the adjacent corner edges 106 extend. Typically, the notch 109 intersects with the floor panel 103, and, is directly between wall folding lines 108 of adjacent peripheral walls 102a-d. The notch may extend along an axis that equally bisects the angle between adjacent wall folding lines 108. Each notch 109 may ease bending of the walls and provide for one or more drainage holes to be present in the finished manhole cover tray.

The blank described above may be integral, i.e. a singular component from which the peripheral walls 102a-d and floor panel 103 are formed. The use of an integral blank and corner edges via the described bending method enables rapid and easy manufacture of trays for use as manhole/drain covers. Normally, such covers are manufactured from tough materials such as steel in order that they can withstand relatively heavy loads from above that are caused by pedestrians or heavy vehicles. Use of welding to manufacture such trays from multiple components has shortcomings by being more labour intensive and having reduced accuracy for obtaining a shape of a tray corresponding to precise specifications necessary for the tray to fit within a frame.

The described tray that is manufactured by bending and interlocking portions of a blank enables quick and precise manufacture, because the dimensions of the assembled manhole cover tray are largely defined by the geometry of the blank. Typically the blank is machine cut or stamped based on predefined moulds. Using these methods, the manufacturing method is quicker, and, there is less scope for geometrical variation in the finished tray that could be caused by human error. Further advantages of the described method include the avoidance of additional fastener hardware such as screws/rivets. The resulting corners are found to be sufficiently strong and permanent for a tray used as a manhole drain cover.

With reference to Fig. 2 there is a finished manhole tray cover 201, after the bending and joining steps discussed above have been completed. It can be observed that the peripheral walls 102a, 102b, 102c, and 102d are all upstanding and enclose a space suitable for receiving a finishing substrate (not shown). It can further be observed that one of the tab portions 105 is joined to peripheral wall 102b via the press-joining procedure described above, although the press-joint itself is not visible in Fig. 2.

Fig. 2 also shows a frame 202, which may surround the manhole tray cover 201 when in-use. The manhole tray cover 201 may be provided independently of the frame 202. Optionally, one or more accessories 203 may be attached to the manhole tray cover.

For example, as shown in Figure 2, the accessories may include as a handle that may be attached to the manhole tray cover to enable easy lifting of the manhole tray cover -e.g. using a lifting key or manhole cover lifting tool.

With reference to Fig. 3a, there is a close-up view of the region around the corner edge 106, with reference numerals corresponding to the features discussed previously. It can be particularly observed that the tab portion 105 does not necessarily extend completely along the upstanding distance of the peripheral wall 102a thereby leaving a non-tabbed portion above and below the tab portion 105 when the manhole cover tray is supported by the floor panel 103. Alternatively, with reference to Fig. 3b, the tab portion 105 may extend to the uppermost edge of the peripheral walls 102a, 102b that is furthest away from the floor panel 103. With reference to both Figs. 3a and 3b, there is a drainage aperture 301 arising as a result of the notch discussed above.

With reference to a side view of the completed manhole tray cover as shown in Fig. 4, tab portions 105 can be observed as hidden from view by dashed lines. Further observable is an angle 104 between peripheral wall 102a and floor panel 103, which would have been defined during the bending of peripheral wall 102a. This angle may be 90 degrees. Alternatively, this angle may be greater than 90 degrees, such as between 92 degrees and 90 degrees. A preferred value for angle 104 is 91.5 degrees.

When the angle 104 is above 90 degrees, the peripheral walls 102a-d can be angled outwardly from the floor panel 103, thereby providing for the tray to be more easily fitted into a frame (e.g. frame features 202 of Fig. 2) or partially within a manhole. The angle 104 can be easily controlled by the bending procedure discussed above, in contrast to the use of other methods such as welding. The press-fit joint (not shown in Fig. 4) is sufficient to keep the peripheral walls bent at the desired angle 104, even when the manhole tray cover is under a load and/or filled with finishing substrate.

Figs. 5 and 6 show an alternative construction to that described above. The reference numerals of Figs. 5 and 6 are in accordance with those described above. It can be observed that the tab portions 105 are outwardly (i.e. outside of the enclosed space of the manhole cover tray 201) of the peripheral walls 102b, 102d. This is in contrast to the tab portions shown in Figs. 1-4 that are inwardly of the peripheral walls (i.e. inside of the enclosed space of the manhole cover tray 201).

With reference to Fig. 7, which includes reference numerals corresponding to features discussed above, an alternative blank may provide two (or more) tab portions 705a, 705b along a corner edge 106 of a peripheral wall 102a, 102c. In this case, each tab portion 705a, 705b is joined to the adjacent peripheral wall 102b, 102d, after the bending steps, by a separate press-joint.

With reference to Fig. 8, which includes reference numerals corresponding to features discussed above, a manhole cover tray 201 is provided from the blank of Fig. 7. In the example of Fig. 8, the tab portions 705a, 705b are outside of the enclosed space of the manhole cover tray 201. However, in other examples, the tab portions 705a, 705b may be inside of the enclosed space of the manhole cover tray 201.

With reference to Fig. 9, which includes reference numerals corresponding to features discussed above, a corner portion of the manhole cover tray discussed above with respect to Fig. 1 is shown. The discussed press-joint 901 is visible on the tab portion 105. In this example, the press-joint is circular, having been formed by a cylindrical punch.

Claims

CLAIMS: 1. A metal manhole cover tray comprising a plurality of peripheral walls surrounding a floor panel to provide a space for receiving a finishing substrate; wherein the plurality of peripheral walls comprises a first peripheral wall and a second peripheral wall; wherein the first peripheral wall comprises a main portion extending upwardly from the floor panel and adjoining the second peripheral wall along a corner edge thereby defining a corner of the tray, the first peripheral wall further comprising a tab portion having been bent to overlap and contact with the second peripheral wall; and wherein the tab portion and second peripheral wall each comprise a region of mutual deformation conforming to one another thereby forming a press-joint between the tab portion and second peripheral wall.
2. A manhole cover tray according to claim 1 wherein the press-joint is circular.
3. A manhole cover according to claim 2 wherein the circular press-joint has a diameter from 40 mm to 60 mm, and is preferably 50 mm.
4. A manhole cover according to any preceding claim wherein the tab portion is a first tab portion, and wherein the first peripheral wall further comprises a second tab portion being bent about the corner edge to be substantially planar with the first tab portion, the second tab portion being joined to the second peripheral wall by an additional press-joint between the second tab portion and the second peripheral wall.
5. A manhole cover tray according to any preceding claim wherein the first and second peripheral walls are at right angles to one another.
6. A manhole cover according to any preceding claim wherein the floor panel defines a plane and the defined corner of the tray is inclined with respect to the normal of the plane.
7. A manhole cover tray according to claim 6 wherein the corner extends at an angle of less than 2 degrees away from the normal of the plane.
8. A manhole cover tray according to claim 6 or claim 7 wherein the corner of the tray is angled away from the normal of the plane and away from the floor panel.
9. A manhole cover tray according to any preceding claim wherein the peripheral walls and floor panel are formed from an integral blank, the peripheral walls being defined by bending corresponding wall portions of the integral blank upwardly.
10. A manhole cover according to any preceding claim further comprising a drainage aperture in between the first peripheral wall and second peripheral wall.
11. A manhole cover according to claim 10, wherein the drainage aperture is formed from a notch in the floor panel
12. A manhole cover according to any preceding claim wherein the floor panel comprises four sides, each side being integral to a corresponding peripheral wall.
13. A manhole cover according to any preceding claim wherein the tab portion is located outside of the space.
14. A manhole cover according to any of claims 1 to 12 wherein the tab portion is located inside of the space.
15. A method of manufacturing a manhole cover tray according to any preceding claim, the method comprising the steps of: obtaining a manhole cover tray blank comprising the floor panel, the first peripheral wall, and the second peripheral wall, wherein the peripheral walls are initially in a planar configuration; a tab bending step comprising bending the tab portion of the first peripheral wall to extend substantially perpendicular to the main portion of the first peripheral wall; a first wall bending step comprising bending the first peripheral wall of the blank to extend outwardly from the floor panel; a second wall bending step comprising bending the second peripheral wall of the blank to extend outwardly from the floor panel; the tab portion and peripheral walls being bent such that the tab portion overlaps the second peripheral wall; and forming a press-joint between the tab portion and second peripheral wall resulting in a region of mutual deformation conforming the tab portion and second peripheral wall to one another.
16. The method according to claim 15 wherein the tab bending step takes place before the first and second wall bending steps.
17. The method according to claim 15 or claim 16 wherein the step of forming the press-joint comprises compressing the tab portion and second peripheral wall together using a cylindrical punch.
18. The method according to any of claims 15 to 17 wherein the step of obtaining comprises stamping or cutting the blank from a metal sheet.