WO2001031142A1

WO2001031142A1 - Duckboard

Info

Publication number: WO2001031142A1
Application number: PCT/SE2000/001773
Authority: WO
Inventors: Lage Olofsson
Original assignee: Lage Olofsson
Priority date: 1999-10-25
Filing date: 2000-09-14
Publication date: 2001-05-03
Also published as: SE9903829L; SE515069C2; SE9903829D0; AU7567500A

Abstract

A duckboard comprises a plurality of long narrow, parallel bars (3, 4) which are kept at a distance from each other by means of short, spaced-apart spacing elements (6), the bars being inter-connected via transverse tie rods (5) which extend through holes in the bars as well as the spacing elements. According to the invention, nearby wooden bars (3, 4) have a cross-section-wise I-shape and two flute-shaped countersinks (8) opening towards opposite directions from a central web (9), which countersinks are delimited by upper and lower flanges (10) which are thicker than the web, the individual spacing element (6) having two opposite side projections (11), which have a cross-section shape that is congruent with the cross-section shape of the countersinks of the bars and which engage the same countersinks.

Description

DUCKBOARD

Technical Field of the Invention

This invention relates to a duckboard of the type that comprises a plurality of long narrow wooden bars, which are kept at a distance from each other in a mutually parallel state by means of shorter, lengthwise spaced-apart spacing elements having in the main the same height as the bars, and which are inter-connected via transverse tie rods, which extend through holes in the bars as well as the spacing elements.

Prior Art

Previously known, commercially available duckboards of the above-mentioned type are used as walking bedding in such scaffolds that are connected to different forms of constructional work. Although the dimensions of such duckboards may vary, the duckboards usually are of a length of approx. 2 metres and a width of approx. 0,5 metres. Characteristic of the conventional duckboards is that the long narrow wpoden bars as well as the intermediate spacing elements, likewise formed by wood, have a generally parallelepipedical shape. In this connection, the long narrow bars are positioned on edge and are delimited by two opposite side surfaces, as well as opposite top and bottom surfaces, the width of which - for several bars - being smaller than half of the height of the side surfaces, and plane end surfaces extending perpendicularly to the aforementioned surfaces. In the standard embodiment thereof, the duckboard includes two outer bars, which are thicker than the bars being on the inside. In practice, the inner bars may be of the thickness of 25 mm and the height of 63 mm, while the two i outer bars have the same height, but a thickness of 38 mm. The spacing elements have a limited length, e.g. 80 mm, and the same height and thickness as the inner bars in the duckboard. An advantage of duckboards of the above-mentioned type is that the skidding security is good because the wooden material offers a relatively abrasive sur ace. However, the conventional duckboards are also associated with a number of disadvantages . One of these disadvantages is due to labour safety technical regulations prescribing a maximum weight, viz . tially manufactured with a weight, which is slightly lower than 25 kg. Subsequently, when the duckboards are used outdoors, it does, however, regularly happen that water is sucked up in the wooden material, whereby the total weight of the duckboard may increase by many kilos. Therefore, during practical use the duckboards have a real weight, which is inappropriate for labour safety technical as well as ergonomic reasons. Another disadvantage is that the spacing elements may swell and shrink in a way which differs from the swelling and shrinkage, respectively, of the long narrow wooden bars when the duckboard is exposed to climatological effects of various types, e.g. effect of varying temperatures and moisture contents. Such a differentiated swelling and shrinkage may entail that small, per se, but still most annoying differences in level and gaps may arise between the spacing elements and nearby bars. Another disadvantage of the known duckboards is that the two opposite ends of the tie rods protrude at least somewhat from the outsides of the two outer bars. These projecting parts of the tie rods may give rise to different forms of problem. For instance, the may get stuck in various way. In a fire-sensitive environment, the projecting portions of the metallic tie rods may furthermore give rise to formation of sparks of an undesired type.

Objects and Features of the Invention

The present invention aims at obviating the above- mentioned disadvantages of previously known duckboards and at providing an improved duckboard. Therefore, a primary object of the invention is to provide a duckboard which, with preserved standard dimensions and strength, may be manufactured with a lower initial weight than the conventional duckboards. Another object is to bring about a stiff duckboard having a stable shape in which the risk of swelling and shrinking, respectively, of the spacing elements and bars in various ways is minimised. It is also an object to provide a duckboard at which occurring tie rods do not protrude sidewards from the two outer bars of the duckboard.

According to the invention, at least the primary object is attained by the features defined in the characteriz- ing clause of claim 1. Preferred embodiments of the invention are furthermore defined in the dependent claims .

Brief Description of the Appended Drawings In the drawings :

Fig 1 is a perspective view of a duckboard according to the invention, Fig 2 is an enlarged, partly cut cross-section through the duckboard according to fig 1, and Fig 3 is an exploded view showing three spaced-apart components included in the duckboard.

Detailed Description of a Preferred Embodiment of the Invention In fig 1, a duckboard 1 according to the invention is shown being laid up on two spaced-apart, horizontal carriers 2. The duckboard is composed of a plurality of long narrow wooden bars 3, 4, which extend parallel to each other and are united by a number of tie rods 5. Between nearby bars, spacing elements 6, 6' are arranged, which are considerably shorter than the bars 3, 4. Also the spacing elements are suitably manufactured from wood. In the example shown, two opposite, outer bars 4 are in a conventional way thicker than the inner bars that are designated 3. The spacing elements 6, 6' have advantageously such dimensions that the width of the air gaps 7 which are formed between nearby bars in the main corresponds with the width or thickness of the inner bars 3. The four corner-wise placed spacing elements which are designated 6 ' are somewhat longer than the other spacing elements and placed in such a way that the outer end surfaces of the elements are in flush with the ends of the duckboards. The other elements 6 are, however, somewhat retracted in relation to the ends of the bars . Furthermore, it should be pointed out that the tie rods 5 extend through holes in the bars as well as the spacing elements. At the two opposite ends of the duckboard, cross pieces (not shown) may be arranged on the bottom side which guarantee that the duckboard do not slide off the carriers.

As far as the shown duckboard has been described hitherto, the same is in all essentials previously known. Characteristic of the present invention is that the wooden bars 3, 4 have a cross-section-wise I-shape and flute- shaped countersinks 8 which open towards opposite directions from a central web 9. These countersinks are delimited by upper and lower flanges 10, which are thicker than the web 9. In addition, the individual spacing elements 6, 6' are formed with two opposite side projections 11, which have a cross-section shape that is congruent with the cross-section shape of the countersinks 8 and which engage said countersinks. In the shown, preferred embodiment, the individual countersink 8 in each bar has a plane side surface 12, which at opposite, upper and lower edges transforms into plane flange surfaces 13, which are oblique in an obtuse angle to the side surface 12. In practice, this obtuse angle may be within the range of 110-135°. In addition, the individual projection 11 on each spacing element has a plane side surface 14, which in the main has the same height or width as the side surface 12 of the countersink. At opposite, upper and lower edges, said side surface 14 transforms into plane chamfering surfaces 15, which extend in the same obtuse angle to the appurtenant side surface 14 as the flange surfaces 13 to the side surface 12 of the bar. At the top, the chamfering surfaces 15 of the side projections transform into plane, vertical surfaces 16 in the same way as the oblique flange surfaces 13 on the bars transform into plane, vertical flange side surfaces 17. When the side projections 11 of the spacing elements are brought to engagement with the flute- shaped countersinks 8 of the bars, the side projections will entirely fill up the countersinks while achieving a form- stiff male-female connection between the spacing elements and the bars .

The upper and lower surfaces 18 of the inner, thin bars 3 have the same width as the corresponding upper and lower plane surfaces 19 of the spacing elements.

At one end thereof, the tie rod 5 has a head 20, which serves as a stopping element for the tie rod. At the opposite end thereof, the tie rod has a male screw, which is in engagement with the female thread of a nut 21.

When the duckboard according to the invention is to be put together, a suitable number of, e.g. four, rods are applied in a vertical state in line one after the other with the stopping elements 20 turned downwards. Then, alternating bars and spacing elements are threaded on the rods while forming a set of components which initially are kept together loosely to subsequently be drawn together by means of the nuts 21 (in practice, a washer, not shown, may also be arranged between the nut and the outer wooden bar) . By the fact that the countersinks 8 in the wooden bars 4 are relatively deep, the stopping element 20 as well as the nut 21 will be in its entirety housed in the countersinks, i.e. the stopping element and the nut, respectively, and the thread-provided end of the tie rod will not protrude outside the outwardly turned flange side surfaces 17 of the outer bars.

In practice, all bars 3, 4 may be of a height of 63 mm, the inner bars 3 having a total width of 25 mm (= the width of the surface 18) , the web 9 being 8 mm thick. At the same time, the outer bars 4 may have a total width of 38 mm, the web being 21 mm thick. The height of the flanges 10, counted as the height of the side surfaces 17, may in all case amount to 8 mm. By the fact that the long narrow wooden bars of the duckboard are formed with an I-shaped cross-section profile, the total weight of the bars may be reduced to a considerable extent without deteriorating the flexural rigidity of the bars. By this weight reduction, the duckboard may be manufactured with a nominal weight which is considerably smaller than the maximum total weight, e.g. 25 kg, for a given duckboard dimension. Another advantage of the duckboard according to the invention is that all spacing elements engage mechanically in the sides of the wooden bars while achieving a strong joint between the bars and the spacing elements when the uniting nuts of the tie rods are tightened. Therefore, a particular form- stiff lattice work is, in practice, formed in which the top and bottom sides of the spacing elements always are kept in the same plane as the top and bottom sides of the wooden bars . In addition, parts of the tie rods will not protrude from the long side surfaces of the duckboard.

Claims

1. Duckboard including a plurality of long narrow wooden bars (3,4) , which are kept at a distance from each other in a mutually parallel state by means of shorter, lengthwise spaced-

5 apart spacing elements (6,6') having in the main the same height as the bars, and which are inter-connected via transverse tie rods (5) , which extend through holes in the bars as well as the spacing elements, c h a r a c t e r i z e d in that nearby wooden bars (3,4) have a cross-section-wise I-shape and

10 two flute-shaped countersinks (8) opening towards opposite directions from a central web (9), which countersinks are delimited by upper and lower flanges (10) which are thicker than the web, and that the individual spacing element (6,6') has two opposite side projections (11), which have a cross-sec-

15 tion shape that is congruent with the cross-section shape of the countersinks (8) of the bars and which engage the same countersinks .

2. Duckboard according to claim 1, c h a r a c t e r i z e d in 20 that the individual countersink (8) in each bar has a plane side surface (12) which at opposite edges transforms into plane flange surfaces (13) , which are oblique in an obtuse angle to the side surface, and the individual side projection (11) on each spacing element (6,6') having a plane side surface (14),

25 which has in the main the same height as the side surface (12) of the countersink and transforms at opposite edges in plane chamfering surfaces (15), which extend in the same obtuse angle to the side surface of the side projection as the flange surfaces to the side surface of the bar.

30

3. Duckboard according to claim 2, c h a r a c t e r i z e d in that said obtuse angle is within the range of 110-135°.

4. Duckboard according to any one of the preceding claims, 35 c h a r a c t e r i z e d in that a stopping element (20) together with a nut (21) at opposite ends of each individual ~^" tie rod (5) are in their entirety housed in outwardly turned countersinks (8) in the two outermost bars (4) of the duckboard .