WO2009022160A1

WO2009022160A1 - Flooring

Info

Publication number: WO2009022160A1
Application number: PCT/GB2008/002790
Authority: WO
Inventors: Alan Williamson
Original assignee: Redman Fisher Engineering Limited
Priority date: 2007-08-15
Filing date: 2008-08-15
Publication date: 2009-02-19
Also published as: GB0715902D0; GB2451867A; GB2451867B

Abstract

Flooring (10) comprising a plurality of elongate load bearing elements (12) joined by a plurality of transverse connecting elements (14) the load bearing elements (12) having an uppermost surface (12a), the uppermost surface (12a) being provided with a tread comprising a plurality of topographical formations, the height of which is between 600μm and 1000μm.

Description

Title: Flooring

Description of Invention

The present invention relates to flooring, particularly open metallic flooring for use in industrial, construction, commercial, retail and architectural applications.

Where non-slip flooring is required for industrial, construction, commercial, retail and architectural sites, it is known to use open flooring comprising a grid of metal bars. Such flooring typically includes a plurality of load bearing bars joined by a plurality of transverse bars. The load bearing bars are made from rolled or slit metal strips and each is arranged with its major surfaces extending perpendicular to the plane of the floor so that one of its longitudinal edges, hereinafter referred to as the bearing edge, provides a bearing surface on which a user walks.

In order to provide the flooring with the required degree of slip resistance to comply with British Standard 4592:Pt0-2006, for example, it is known to provide the bearing edge with a tread in the form of a plurality of serrations with a peak to valley height of the order of 3mm. The serrations are of such as size that they can lock into a typical tread used in industrial safety footwear, and thus provide the desired high static coefficient of friction between shoe and the flooring.

Traditionally virtually all industrial and safety footwear had cleated soles, but developments in footwear to achieve better anti-slip properties has resulted in a myriad of new types of industrial or safety footwear many of which do not have cleated soles. Testing of industrial flooring to establish whether it has the required degree of slip resistance to comply with BS4592:Pt0-2006 is therefore carried out using smooth soled footwear. Thus, to achieve the required degree of slip resistance to meet the relevant standards, further increase in friction is required, and this has been achieved by increasing the sharpness of the peak of each serration. This can result in damage to the sole of a shoe in contact with the floor, thus increasing wear of footwear, and even increase the risk of injury through lacerations on falling. Moreover, when such flooring is used by a wearer of footwear with cleated soles, the friction between the footwear and the flooring can be so high that walking on the flooring causes the user excessive fatigue.

According to a first aspect of the invention we provide a flooring comprising a plurality of elongate load bearing elements joined by a plurality of transverse connecting elements the load bearing elements having an uppermost surface, the uppermost surface being provided with a tread comprising a plurality of topographical formations, the height of which is between 600μm and 1000μm.

The topographical formations are preferably a series of generally parallel ridges, in which case, the ridges preferably extend generally perpendicular to the longitudinal axis of the load bearing element. The topographical formations may alternatively be a plurality of peaks.

When viewed in longitudinal cross-section (i.e. a vertical cross-section parallel to the longitudinal axis of the load bearing element) the topographical formations are preferably generally asymmetrical, and may have a first edge and a second edge which has a different curvature to the first edge.

The topographical formations are preferably arranged in clusters over a proportion of the surface area of the uppermost surface. Adjacent clusters of topographical formations may be separated by a groove having a depth which is significantly greater than the height of the topographical formations.

The separation of the highest points of adjacent topographical formations is preferably between 500μm and 3000μm.

The material ratio of the bearing surface is between 5/25mm and 11 /25mm measured to 600μm depth. Advantageously, the load bearing elements are made from metal strips and each is arranged with its major surfaces extending perpendicular to the plane of the floor so that one of its longitudinal edges forms the uppermost surface. When viewed in transverse cross-section (i.e. a vertical cross-section perpendicular to the longitudinal axis of the load-bearing element), the topographical formations may have a central portion which extends generally parallel to the plane of the flooring, and two edge portions which extend from either edge of the central portion to the major surfaces of the load bearing element.

The connecting elements may be generally cylindrical rods, or may be formed from a twisted square cross-section rod.

According to a second aspect of the invention we provide a method of making a load bearing element for a flooring comprising a plurality of elongate load bearing elements joined by a plurality of transverse connecting elements, the load bearing elements having an uppermost surface, the method including forming in the uppermost surface a plurality of topographical formations, the height of which is between 600μm and 1000μm.

Preferably the load bearing element is metallic, and the method includes the steps of rolling the load bearing element into an elongate strip, and forming the topographical formations on one of the longitudinal minor surfaces of the strip.

Advantageously the topographical formations comprise a plurality of ridges and the method includes the step of forming the ridges by rolling of a knurled roller along the bearing edge of the load bearing element.

Embodiments of the invention will now be described with reference to the following drawings of which:

FIGURE 1 is an illustration of a section of flooring according to the first aspect of the invention; FIGURE 2 is an illustration of detail of a load bearing bar of the flooring shown in Figure 1 ,

FIGURE 3 is an illustration of an alternative configuration of load bearing bar to that shown in Figure 2,

FIGURE 4 is an illustration of the profile of the topographical formations applied to the bearing edge of the load bearing bars shown in Figures 2 and 3,

FIGURE 5 is an illustration of the longitudinal cross-section through a further alternative configuration of load bearing bar, showing a magnified view of a) a first possible configuration of topographical formation, b) a second possible configuration of topographical formation, and

FIGURE 6 is an illustration of the transverse cross-section of the load bearing bar illustrated in Figure 5.

Referring now to Figure 1 , there is shown a section of flooring 10 comprising a grid formed from a plurality of parallel load bearing bars 12, and a plurality of transverse bars 14 joining the load bearing bars 12. The load bearing bars 12 are formed from strips of a metallic material and are each arranged with its major surfaces 12b extending generally perpendicular to the plane of the floor, so that one of the longitudinal edges of each bar 12 provides a surface on which a user may walk, hereinafter referred to as the bearing edge 12a. The load bearing bars 12 and transverse bars 14 are preferably made of steel, which may be galvanised to improve its corrosion resistance.

In this example, each transverse bar 14 is formed from a rod with a generally circular transverse cross-section, and extends with its longitudinal axis generally perpendicular to the longitudinal axes of the load bearing bars 12. The transverse bars 14 are mounted in a plurality of appropriately spaced slots in the bars 12, preferably so that the uppermost surface of each transverse bar 14 lies below the uppermost surface of the load bearing bars 12, and welded to the load bearing bars 12 in a manner which is conventional in the production of such flooring. The transverse bars 14 may alternatively be made from a twisted rod with a generally square cross-section, and may be secured to the load bearing bars 12 by placing the transverse bars 14 on the bearing surfaces 12a of the load bearing bars 12 and forge welding the transverse bars 14 in place.

Referring now to Figure 2, in which the bearing edge 12a of load bearing bar 12 is shown in more detail, the bearing edge 12a is, on a macroscopic scale, generally flat, but is provided with a tread in the form of a plurality of ridges 16 which extend generally perpendicular to the longitudinal axis of the bearing edge 12a. In this example, the ridges 16 are around 800μm in height (Rz as defined in BS1134), with a mean peak-to-peak spacing (S as defined in BS1134) of around 20Q0μm. To avoid excessive wear of a user's footwear, the ridges 16 are shaped such that the material ratio is of the order of 11mm/25mm at a depth of 600μm. The material ratio (Mr as defined in BS1134) is defined as the length of flooring in contact with a flat sole penetrated by the ridges 16 to a depth of 600μm over a specified length of flooring i.e. (xi + Xz +X3 + X4 + Xs/μm), as illustrated in Figure 4.

It should be appreciated that, to achieve the desired slip-resistance, the surface roughness profile need not be exactly as illustrated in Figure 4 - the mean ridge height may be between 600μm and 1000μm, and the mean peak- to-peak spacing may be between 1500μm and 3000μm, or may even be as low as 500μm.

The surface roughness profile may comprise a plurality of conical, pyramidal, or approximately conical or pyramidal peaks rather than ridges, and or could be applied to a bearing edge 12a which is not generally flat on a macroscopic scale, as illustrated in Figure 3. In this embodiment of the invention, the bearing edge 12a is provided with a plurality of macroscopic serrations, of comparable size to the serrations used in prior art flooring, i.e. around 3mm in height, and around 20mm peak-to-peak spacing. The top portion, around 10mm in length, of each serration is provided with the surface roughness profile similar to that described above, i.e. with a plurality of ridges 16 having a height of around δOOμm and a peak-to-peak separation of around 2000μm. In other words, the ridges 16 are provided in clusters of around five ridges, adjacent clusters being separated by a groove 18 of around 3mm in depth. The material ratio Mr of this embodiment of the invention is around 5mm/25mm at 600μm depth.

A further alternative embodiment of the invention is illustrated in Figure 5. in this embodiment, the topographical formations 16 are arranged in clusters of five, each cluster being separated by a substantially flat bottomed groove 18. In this example the peak-to-peak separation 5 of the topographical formations is 2.5mm, the height R_z of the topographical formations relative to each other is 0.8mm, and 2.5mm relative to the lowermost part of the groove 18. The distance between the first topographical formation 16 in one cluster and the last in an adjacent cluster is 10.5mm. In this example, rather than being purely ridges, which have the same height across the full width of the load bearing bar 12, or conical or pyramidal peaks, the topographical formations, when viewed in transverse cross-section as shown in Figure 6, each have a central portion 20, which may be slightly domed or generally flat, which lies generally perpendicular to the major surfaces 12b of the bar 12 (i.e. parallel to the plane of the flooring), and two sloping edge portions 22, which may be slightly curved or substantially flat and which extend from the edges of the central portion 20 to the major surfaces 12b of the bar 12. The topographical formations 16 therefore appear to have the form of a triangle with the uppermost point removed, when viewed in transverse cross-section. It is believed that forming the topographical formations 16 in this way may enhance the slip resistance of the flooring in a direction generally perpendicular to the loading bearing bars 12.

It has also been found that the slip resistance of the flooring can be enhanced further by ensuring that, when viewed in longitudinal cross-section, as shown in Figure 5, each formation 16 is asymmetrical. In particular, each formation 16 has a first edge 16a and a second edge 16b, which has a different radius of curvature to the first edge 16a. One or both of these edges 16a, 16b, may be curved as illustrated in Figure 5a and 5b. The two edges 16a, 16b, may meet at a point, as illustrated in Figure 5b or may be separated by a third edge 16c, as illustrated in Figure 5a.

Whilst in the examples shown in Figures 3 and 5, there are five topographical formations in each cluster, and the length (parallel to the longitudinal axis of the load bearing bar 12) of each groove 18 is around a third of the length of each cluster of topographical formations 16, this need not be the case, and more or fewer topographical formations 16 may be provided in each cluster. For example, a further alternative embodiment of the invention includes only three topographical formations in each cluster.

Unlike in the prior art flooring, flooring according to the invention does not rely on the cleated soles of industrial flooring locking into serrations on the bearing edges of the flooring to achieve the desired slip-resistance. The ridges of the surface roughness profile applied to flooring according to the invention are too small and closely spaced for this to occur. Instead, the desired slip resistance is achieved by virtue of elastic deformation of the sole of a user's footwear around the ridges. Use of surface roughness profiles having the parameters set out above has been found to produce a flooring with the desired slip resistance which does not cause significant damage to a user's footwear. Moreover, by appropriate combination of R_z, S, Mr and footwear excessive user fatigue may be reduced or avoided.

The desired slip resistance can be achieved using the profiles described above even when the steel bars are galvanized, despite the fact that galvanized steel floors tend to have poorer slip properties than ungalvanized steel floors, as the galvanized metal polishes rapidly when in use.

The load bearing bars 12 are preferably fabricated by hot rolling, and if this is the case, the surface roughness profile described above is provided by applying a knurled roller, with a surface profile which is generally the inverse of the desired surface roughness profile, to the bearing edge of each bar as a continuous part of the hot rolling process, during the later stages of the process. The surface profile of the knurled roller may vary slightly from the precise inverse of the desired surface profile, to allow for the fact that the bar material may not completely fill the valleys in the surface profile of the knurled roller during rolling if application of the pressure required to achieve complete matching of the profiles would cause unwanted macroscopic deformation of the bar.

The hot rolling process is substantially the same as the process of hot rolling the load bearing bars for conventional metallic flooring, except that at stand 8 of the rolling process, the side of the bar adjacent the bearing edge are tapered inwards to produce a truncated triangular portion in transverse cross- section. This is done to provide space for excess material to flow into during subsequent rolling operation without any unwanted bulges being formed in the cross-section of the bar. At stand 9 of the rolling process, the thickness of the bar is reduced, the surface roughness profile is applied at stand 10, and the thickness of the bar is reduced to its final value at stand 11.

The bars may alternatively be produced by taking a rolled plate of the desired thickness, and cutting it into a plurality of strips of the desired depth. In this case, the surface roughness profile is applied in a separate cold rolling process after the slitting operation.

A final alternative fabrication method is to cast the bars, in which case the surface roughness profile is incorporated into the mold shape.

The load bearing bars 12 may be galvanised once formed to the desired shape.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. Flooring comprising a plurality of elongate load bearing elements joined by a plurality of transverse connecting elements the load bearing elements having an uppermost surface, the uppermost surface being provided with a tread comprising a plurality of topographical formations, the height of which is between 600μm and 1000μm.

2. Flooring according to claim 1 wherein the topographical formations are a series of generally parallel ridges.

3. Flooring according to claim 2 wherein the ridges extend generally perpendicular to the longitudinal axis of the load bearing element.

4. Flooring according to claim 1 wherein the topographical formations are a plurality of peaks.

5. Flooring according to any preceding claim wherein the topographical formations, when viewed in longitudinal cross-section, are generally asymmetrical.

6. Flooring according to any preceding claim wherein the topographical formations, when viewed in longitudinal cross-section have a first edge and a second edge which has a different curvature to the first edge.

7. Flooring according to any one of claims 1 to 6 wherein the topographical formations are arranged in clusters over a proportion of the surface area of the uppermost surface.

8. Flooring according to claim 7 wherein adjacent clusters of topographical formations are separated by a groove having a depth which is significantly greater than the height of the topographical formations.

9. Flooring according to any preceding claim wherein the separation of the highest points of adjacent topographical formations is preferably between 500μm and 3000μm.

10. Flooring according to any preceding claim wherein the load bearing elements are made from metal strips and each is arranged with its major surfaces extending perpendicular to the plane of the floor so that one of its longitudinal edges forms the uppermost surface.

11. A flooring according to claim 10 wherein the topographical formations, when viewed in transverse cross-section, have a central portion which extends generally parallel to the plane of the flooring, and two edge portions which extend from either edge of the central portion to the major surfaces of the load bearing element.

12. Flooring according to any preceding claim wherein the connecting elements are generally cylindrical rods.

13. A method of making a load bearing element for a flooring comprising a plurality of elongate load bearing elements joined by a plurality of transverse connecting elements, the load bearing elements having an uppermost surface, the method including the forming in the uppermost surface a plurality of topographical formations, the height of which is between 600μm and 1000μm.

14. A method according to claim 13 wherein the load bearing element is metallic, and the method includes the steps of rolling the load bearing element into an elongate strip, and forming the topographical formations on one of the longitudinal minor surfaces of the strip.

15. A method according to claim 13 or 14 wherein the topographical formations comprise a plurality of ridges and the method includes the step of forming the ridges by rolling of a knurled roller along the bearing edge of the load bearing element.

16. A flooring substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

17. A method of making a flooring substantially as hereinbefore described with reference to the accompanying drawings.

18. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.