Title: Improvements relating to open flooring.

Technical field:

THIS INVENTION relates to open flooring comprising a plurality of longitudinal bars which are parallel to each other and are connected together by transverse bars.

Background art:

There are two kinds of open flooring in common use. The first kind is frequently referred to as diamond pattern flooring and in this kind each transverse bar lies between a pair of adjacent longitudinal bars, is non-rectilinear and is attached to the longitudinal bars alternatively at successive positions along the length of the transverse bar. The second kind is referred to hereinafter as flooring of the kind specified. In flooring of the kind specified, each transverse bar extends across more than two longitudinal bars. Usually, in flooring of the kind specified, each transverse bar is rectilinear and parallel to the other transverse bars.

In open flooring of both of the kinds hereinbefore mentioned, the longitudinal bars are usuall^r intended to bear any imposed downward load, whilst the transverse bars are intended primarily to hold the longitudinal bars in the required relative positions. The transverse bars are spaced further apart from one another than are the longitudinal bars. The longitudinal bars usually have a rectangular cross—section, the longer dimension being vertical in use to provide the required load bearing

ability without the use of an excessive quantity of material. In use, the longitudinal bars are directly supported by beams or other suitable supports and the transverse bars are directly supported only by the longitudinal bars.

There is a requirement for open flooring to be constructed with narrow gaps between adjacent bars, in order to reduce the risk of danger to personnel or damage to equipment from objects falling through the flooring, u* this requirement conflicts with the requirement to achieve the required load bearing ability with the minimu of material.

Disclosure of Invention:

According to a first aspect of the invention, a flo comprises a first set of bars, the bars of the first set being rectilinear, spaced apart and parallel to each othe a second set of bars, each bar of the second set being transverse to the bars of the first set and connecting together more than two bars of the first set and a plural °f intermediate elements, each intermediate element lying between a pair of adjacent bars of the first set, wherein each intermediate element lies at least partly below and is attached to bars of the second set.

With this arrangement, the intermediate elements prevent objects which could fall between the bars of the first set from falling through the floor. Because the intermediate elements lie below the bars of the second se the intermediate elements do not normally bear any load since the load is borne by the bars of the first and seco sets.

According to a second aspect of the invention, there is provided a panel of open flooring comprising a first set of bars, the bars of the first set being rectilinear, spaced apart and parallel to each other, a second set of bars, each bar of the second set being transverse to the bars of the first set, connecting together more than two bars of the first set and having a cross sectional area greater than that of the bars of the first set, and a plurality of intermediate elements, each intermediate element having a cross sectional area less than that of the bars of the first set, lying between a pair of adjacent bars of the first set, being attached to bars of the second set and being spaced from both of the planes containing edges of the first set of bars.

When a panel in accordance with the second aspect of the invention is arranged horizontally in a floor, the intermediate elements are spaced downardly from upper edges of the bars of the first set and so are not normally subjected to any load.

According to a third aspect of the invention, there is provided a method of producing flooring panels for use in a floor according to the first aspect of the invention, the method being characterised in that a plurality of longitudinal bars are arranged parallel to each other and spaced apart by gaps each containing an elongate element which is parallel to the longitudinal bars, the cross sectional area of each intermediate element being smaller than the cross sectional area of each longitudinal bar, a plurality of transverse bars are brought into contact with the longitudinal bars and secured thereto and the transverse bars are secured to the elongate elements either

before or concurrently with securing of the transverse ba to the longitudinal bars.

Brief description of drawings:

One example of flooring embodying the first and second aspects of the invention, and produced by a method according to the third aspect of the invention, will now be described with reference to the accompanying drawings wherein:

FIGURE 1 shows a plan view of flooring, FIGURE 2 shows a cross section of the flooring, and

FIGURE 3 illustrates the method of producing the flooring.

Best Mode of carrying out the invention:

Panels of open flooring are normally prefabricated and then transported to the site. at which the flooring is to be erected, where the panels are laid side by side on suitable supports. The expression "open flooring" as use herein refers both to- individual panels and to an assembl of such panels which constitutes a complete floor.

The panels are usually rectangular, although panels of different shapes may be fabricated to fit around membe which are to extend through the flooring. A part of a panel is shown in Figure 1. This panel includes a set of longitudinal bars 10 which are connected together by a set of transverse bars 11. The longitudinal bars are rectilinear, are spaced from and parallel to each other and have a rectangular cross-section, the longer dimensi of which extends vertically when the panel is horizontal. When the flooring is in use, end portions of the longitud inal bars rest on supports, for example, beams supported by pillars or by walls of a building in which the floorin is provided. Further supports for the longitudinal bars be provided between the end portions thereof.

Each of the transverse bars 11 extends across all of the longitudinal bars 10 of the panel and lies in corres _¬ ponding notches formed in upper edges of the longitudinal bars. The transverse bars are secured to the longitudinal bars by fusion. The transverse bars are directly supported only by the longitudinal bars.

Any downward load which is applied to a transverse bar in use is transmitted to a support through the inter¬ mediary of the longitudinal bars 10.

When the flooring is in use, the edges of the longitud¬ inal bars 10 which are adjacent to the transverse bars 11 are the uppermost edges of the longitudinal bars. Between the longitudinal bars and below the transverse bars 11 there lie intermediate elements 12. The intermediate elements lie below the plane containing the uppermost edges of the longitudinal bars and do not normally bear any load when flooring is in use. It will be noted that the cross sectional area of each intermediate element 12 is a plurality of times less than the cross sectional area of each longitudinal bar 10. The intermediate elements and the transverse bars lie above the plane containing the lower edges of the longitudinal bars.

Typically, the longitudinal bars have a width of mm and a depth of 30 mm and the intermediate elements 12 are formed of round wire having a diameter of approximately 7 mm. Alternatively, the intermediate elements may be formed of square cross section wire which is twisted about its longitudinal axis and has a similar cross sectional area to that of the round wire. In the particular example of flooring illustrated in the accompanying drawings, the pitch of the longitudinal bars 10 is 30 mm, there is a single intermediate element in each gap between adjacent longitudinal bars and the gaps between the elongate elements and adjacent longitudinal bars are approximately 9 mm wide.

In the particular example of flooring illustrated, the longitudinal bars 10, transverse bars 11 and inter¬ mediate elements 12 are all rectilinear, the intermediate elements are parallel to the longitudinal bars and lie centrally in the gaps between adjacent longitudinal bars and the transverse bars are perpendicular to the longitudinal bars and elongate elements. The transverse bars may have a substantially square cross-section but be twisted about their respective longitudinal axes.

One method of producing the flooring is illustrated in Figure 3. In this method, the required number of longitudinal bars 10 and intermediate elements 12 are supported in the required relative positions by a support 13. The support is in the form of a platform having in its upwardly presented face recesses 1 for the longitud¬ inal bars 10 and recesses 15 for the intermediate elements 12. The depth of each of the recesses h is less than the depth of the longitudinal bars by an amount approximately equal to the depth of the transverse bars 11 so that the longitudinal bars project upwardly from the support. The depth of each of the recesses 15 is a small amount less, typically 10% less, than the thickness of the intermediate elements 12 so that these elements project only slightly from the support. The support 13 extends along only a part of the lengths of the longitudinal bars and inter¬ mediate elements, typically for a distance between one and two times the pitch of the transverse bars 11.

The apparatus for producing the flooring further comprises a pair of electrodes 16 and 17 which are disposed above the support 13 and each has a length approximately equal to the length of the support so that the electrodes extend across the entire width of the flooring to be

produced. The electrodes are spaced apart in a direction along the lengths of the longitudinal bars 10 so that respective longitudinal centre lines of the electrodes are spaced apart by a distance equal to the pitch of the transverse bars 11. The electrodes are mounted by means not shown for reciprocation towards and away from the support 13.

With the electrodes l6 and 17 raised clear of the longitudinal bars 10 and intermediate elements 12 supported by the platform 13, two transverse bars 11 are laid across the exposed edges of the longitudinal bars at positions directly below respective ones of the electrodes. The electrodes are then lowered into contact with respective ones of the transverse bars and an electric current is passed from the electrode l6 through the corresponding transverse bar, through the longitudinal bars 10 and the other transverse bar to the electrode 17. This causes resistance heating of the longitudinal bars at the posi¬ tions where these are crossed by the transverse bars. The transverse bars are forced downwardly by the electrodes to form notches in the upper edges of the longitudinal bars. As the depth of these notches approaches the depth of the transverse bars, the latter come into contact with the intermediate elements 12 and electric current is then conducted by the intermediate elements also so that heating occurs at the positions where the transverse bars cross the intermediate elements. In this manner, the transverse bars are welded to both the longitudinal bars and the intermediate elements. Down- ward movement of the transverse bars is terminated before these engage the support 13.

When one pair of transverse bars have been united with the longitudinal bars and the intermediate elements, the electrodes l6 and 17 are withdrawn upwardly, the

longitudinal bars and intermediate elements are advanced by a distance equal to twice the pitch of the transverse bars and a further pair of transverse bars is applied to the longitudinal bars.

In an alternative method of producing the flooring, a grid comprising the transverse bars 11 and the inter¬ mediate elements 12 is formed. The transverse bars and the intermediate elements are arranged at a pitch equal to the pitch which is to be established for the long- itudinal bars. The intermediate elements are then secured to the transverse bars by welding. An array of parallel longitudinal bars is then brought into contact with the grid and the relative positions required in the finished flooring is established. The transverse bars are then secured to the longitudinal bars by forge welding similar to that described with reference to Figure 3.

In either of the methods described, the flooring panel may be completed the provision of additional bars connecting together the free ends of the longitudinal bars.

In the particular example illustrated in the drawings, the intermediate elements 12 lie substantially entirely below the transverse bars 11. If required, the intermediate elements may be supported prior to application of the transverse bars at a level somewhat nearer to the plane containing the upper edges of the longitudinal bars 10. The intermediate elements will then overlap somewhat vertically with the transverse bars but it is preferred that the intermediate elements should lie at least partly below the transverse bars, in order that the application of load to the intermediate elements during normal use of the flooring can be avoided. It will be noted that the intermediate elements are spaced from each of the

planes which contains edges of the longitudinal bars. Thus, even if panels of the flooring are stored with the transverse bars 11 at the lower edges of the longitudinal bars, it is unlikely that any significant load will be applied to the intermediate elements.