GB2255526A

GB2255526A - A tarpaulin-type cover comprising an edge-strengthening band containing holes

Info

Publication number: GB2255526A
Application number: GB9208112A
Authority: GB
Inventors: Dieter Jablonka; Klaus Urban; Gerhard Marschitschek; Dirk Jurgensen
Original assignee: Doerken Ewald Co KG GmbH
Current assignee: Doerken Ewald Co KG GmbH
Priority date: 1991-05-07
Filing date: 1992-04-13
Publication date: 1992-11-11
Also published as: DK59692D0; GR1001168B; DK59692A; IE921458A1; ITMI921085A0; PT100454A; FR2676484A1; FI922041A0; NO921109D0; ES2064198A2; IT1255139B; CH685618A5; BE1005023A3; SE9201371D0; LU88069A1; NL9200476A; DE4114802C2; ITMI921085A1; DE4114802A1; ES2064198B1

Description

z'235526 A TARPAULIN-TYPE COVER COMPRISING AN EDGE-STRENGTHENING BAND

CONTAINING HOLES The invention relates to a tarpaqlin-type cover comprising an edge- strengthening band containing holes.

Covers of this type are employed as scaffolding covers for example. They are preferably manufactured from woven cloths, plastic coated woven cloths, plastic sheets and plastic sheets strenghtened by open-textured cloths, knitted fabrics, clumps of fibres, and mats of tangled fibres. Such sheets are provided with edge-strengthening bands which contain holes for the engagement of fastening means, such as lashing belts, tensioning ropes or the like. For example a cover of this general type. is known from DE 23 56 028 C3 wherein holes are provided exclusively in the edge-strengthening bands and these edge-strengthening bands containing holes are applied on one or both sides of the edge of the cover, which does not itself contain holes, and are irreversibly fixed to the cover. Other covers are also known wherein not only do the edge- strengthening bands contain holes but the covers also contain preformed holes in the region of the holes in the edge-strengthening band. Furthermore covers are known the holes in which are formed by elements which can be removed or pushed out of the cover and/or edge-strengthening band, so that the user can open and use such an hole as and when he wishes. Such covers are used not only as scaffolding covers but are also used as protective covers for optionally protecting materials from effects due to weather conditions, or as covers for freight carrying lorries, as protective covers for railway or postal traffic or for many other purposes. Covers which are provided with eyelets or other means for strengthening the edges of the holes in order to improve the resistance to tearing in the hole region also come within this general heading.

In the case of the previously known covers an effect occurs when ropes or similar fastening means are inserted through the corresponding holes in the edge-strengthening band such that when appropriate forces are encountered, for example caused by the wind or the like, the individual holes do not tear towards the edge of the cover but instead the edge-strengthening band tears away from the cover along its side facing away from the edge of the cover. This is known to persons involved in this field as the "zip fastener effect!. This effect also occurs in the case of other covers of this general type comprising an edge- strengthening band containing holes.

Starting from this state of the art the aim of the invention is to provide a cover comprising an edge-stre ng then! ng band containing holes, with which the transference of forces occurring in the hole region into the surface area of the cover occurs in an improved manner so that the socalled zip fastener effect is decreased or suppressed.

To achieve this objective the invention proposes alternative solutions.

A first solution is characterized in that the holes in the edgestrengthening band are arranged eccentrically in the latter and are displaced towards the edge of the cover adjacent to the edgestrengthening band.

As a result of this construction an improved transference of force into the surface of the cover is obtained, because with the envisaged force acting at right angles relative to the edge of the cover on the holes and on the edge-strengthening band, the resultant forces are distributed over a surface spread over 45 on both sides of the line along which the force is applied and the hypotenuse of this surface, which is formed by the relatively internal effective side edge of the strengthening band, is increased as a result of the eccentric arrangement of the holes in the edge- streng the ni ng band. Fundamentally it is advantageous with this construction if a wider edge-stre ng then! ng band is used than was previously used so that the width of the region between the holes and the edge of the strengthening band nearer the side edge of the cover is at least equal in size to that which was previously customary in the state of the art, whereas the width of the strengthening band towards 1 its other side, in other words that towards the covering surface, is considerably greater.

For example the width between the holes and the edge of the strengthening band facing towards the cover may be twice as large as the width between the holes and the edge of the strengthening band facing towards the edge of the cover.

Claims

An alternative manner in which the objective described in the introduction

may be achieved, but which can also be used in combination with the characterizing features of Claim 1, is characterized in that in the region of the holes the edge-strengthening band is widened towards the region of the cover facing ai&ay from the edge of the cover adjacent to the band.

An advantageous further development of this is characterized in that the width of the additional widening region perpendicular to the longitudinal extent of the edge-streng then! ng band in the plane of the cover is at least half the width of the edge-stre ng then! ng band in the region which is not widened.

Furthermore it is preferably arranged that the length of the widened region is at least twice the width of the edge-stre ng then! ng band measured from the hole to the edge of the edge- stre ng theni ng band Which faces away from the side edge of the cover adjacent to the band.

Particularly advantageously it is arranged that the edge-strengthening band is formed so that the transition from the not widened region to the widened region occurs along a i%eve-like line.

Consequently, because in the region near the holes in the edgestrengthening band the edge-streng then! ng band is widened toi&erds the region of the cover facing away from the edge of the cover adjacent to the band, in this region the desired improved transference of force Into the cover surface is obtained, where as a result of the widening the Z hypotenuse of the triangle of force lines produced from the resultant forces is made longer. The width and length measurements of the widened zone should therefore be determined in dependence on the length which should be chosen for the hypotenuse of this triangle. Preferably the length of this should be approximately double the width of the edgestrengthening band measured from the hole to the edge of the edgestrengthening band which faces away from the side edge of the cover adjacent to the band. In the case of the preferred structure wherein the widened region has a wave-like form,. the force transference line (separating line) between the edge-strengthening band and the cover (on the side facing away from the si-de edge of the cover) is lengthened even more since, governed by the wave form. a longer force transference line is fonned.

In the case of this construction it is also advantageous that, as in the case of a toothed structure of the edge-stre ng then i ng band, less material is required to manufacture it. Optionally such a wave-like or toothed strengthening band can be stamped out with no wastage from a band having parallel longitudinal edges, whereby two symmetrical mirror image edge-strengthening bands are fomed. These can then be attached to the cover in an already known manner.

Another alternative manner of achieving the objective described in the introduction consists of arranging that the cover in the region of the edge- streng the ni ng band and a zone connected onto the latter, facing away from the edge of the cover adjacent to the band, is reinforced by a reinforcing insert moulded in it or on it and attached flush with the cover in the form of deposited material, a lattice, a woven web or a mat.

By introducing such a reinforcing insert an improved force transference over a greater surface region of the cover surface itself is obtained, because the force transference extends, starting from the element engaged in the hole in the edge-stre ng then! ng band, and then across the reinforcing insert, as far as the side edge of the latter located towards the interior of the cover.

7 The reinforcing insert may be arranged eccentrically in accordance with the characterizing features of Claim 1, or it is also possible to construct the reinforcing insert In such a manner as is indicated with regard to the edge-strengthening band in Claims 2 to 5.

An arrangement in accordance with Claim 1 or in accordance with Claims 2 to 5 may also be advantageously used in combination with a reinforcing insert of this kind.

Another alternative solution, which in particular is also advantageous in combination with Claims 6 and 7, is described in Claim 8.

The characteristic feature of a further development of this stated in Claim 9.

i S It has been found that covers with reinforcing inserts applied over all the surface in the form of lattices or the like also tear in the edge region of the edge- stre ng then! ng band because a "notch stress effect" is caused by the lattice in this region as a result of the structure of the lattice mesh extending parallel to the side edge of the strengthening band. This occurs in particular with covers which are manufactured in such a manner that a lattice mesh is first placed on a previously prepared plastic sheet and then a second sheet is extruded over the lattice mesh. Thereby thin regions, dependent on the manufacturing conditions, are caused in the material of the extruded second sheet near the strands of the lattice, and these result in a weakening of the sheet and consequently an increased risk of tearing.

If, in accordance with the proposals of the invention, a mat is laid on the lattice structure before the extrusion of the second sheet, and only after this is the second plastic sheet extruded for the fomation of the cover, then the strands of the lattice are almost completely concealed by the overlying mat layer so that localised thinning of the material in the region of the second sheet extruded onto it does not occur or is insignificant. The effect of the extruder rollers i 1 i hv itself causes the mat to be compressed and then a substantially flat surface, showing no surfaces of the lattice structure., is produced as the surface on which to extrude the second sheet. Hereby the tendency to tear is already greatly decreased, and this effect is particularly advantageous in combination with the arrangements described as characterizing features of Claims 1 to 7.

Examples of embodiments of the invention are shown in the drawings and are described, by way of example only, with reference to the following drawings in which:

Figure 1 shows a highly schematic top view of a first embodiment; Figures 2 to 4 show similar views of other embodiments; and, Figures 5 and 6 show cross-sections of the embodiment shown in Figure 4 along the lines V and VI respectively in Figure 4.

Figure 1 shows a cover 1 comprising an edge-strengthening band 2 and holes 3 located therein. The holes 3 in the edge-strengthening band 2 are arranged eccentrically in the latter and are displaced towards the edge of the cover 4 adjacent to the band. The structure of the edge- strengthening band known in the state of the art and used prev iously is indicated by the dashed line 5. In the state of the art the hole 3 was located in the middl-e of the edge-strengthening band 2. Thereby virtually only the region L] was available as a force transference line. As a result of the eccentric arrangement of the holes 3 the force transference line is extended to the length L2, it having been assumed that the force is applied in the direction of the arrow K and a force field results from this between the W-lines 6, the hypotenuse of which is formed by the length L2 of the side edge of the band.

In the case of the embodiment example shown in Figure 2 the edgestrengthening band 2 is widened near the holes 3 towards the region of the cover 1 facing away from the edge of the cover 4 adjacent to the hand. On the contrary in the region not containing holes the edge- strengthening band 2 is not widened. The width of the widening zone at right angles to the longitudinal extent of the edge-strengthening band 2 measured in the plane of the cover corresponds to at least half the width of the edgestrengthening band 2 in the region which is not widened. The length of the widening zone corresponds to at least twice the width of the edgestrengthening band 2 measured from the hole 3 to the edge of the edgestrengthen i ng band 2 which faces away from the edge of the cover 4 adjacent to the band. This embodiment example is a preferred embodiment in which the transition of the edge- strengthening band 2 from the not widened region to the widened zone has a wave-like shape. Thereby a line of length L3 is produced as the force transferring line, which is considerably longer in comparison with the embodiment known in the state of the art (length 0), and so an improvement in the force transferrence and consequently a reduction of the so-called zip astener effect is obtained.

In the case of the embodiment example shown in Figure 3, the cover 1, in the region of the edge-strengthening band 2 and of a zone 7 adjacent to the latter, on an opposite side of the band from the edge 4 of the cover, is reinforced by a reinforcing insert 8 moulded in it or on it and attached flush with the cover 1 in the form of deposited material, a lattice, a woven web or a mat. The reinforcing insert 8 produces an improved transferrence of force since, when forces are applied in the direction of the arrow K and the force effect lines 6 result from this, the effect of this force is transferred onto the reinforcing insert 8 and consequently virtually the length L4 can be used as the reference length for the force transferrence line. It is of course obvious that it is also possible to combine this structure with the features in accordance with the embodiment examples shown in Figures 1 and 2.

Figures 4 to 6 show a cover 1 comprising an edge-strengthening band 2 wherein the cover 1 is reinforced over the whole surface by means of two plastic sheets 9, 10 and a reinforcing insert in the form of a lattice mesh 11 moulded between them. In the region where the edge-strengthening band 2 exerts an effect a mat 12 is inserted between zhe reinforcing insert 11 and the second plastic sheet 10, which covers the insert, and the mat is pressed together with the sheets. The effect caused by this is clearly shown in Figures 5 and 6. Figure 5 shows a region 2 of the cover which does not contain the matting layer 12. During manufacture the lower sheet 1 is first laid out and the lattice mesh 11 is laid on this sheet. The sheet 10 is then extruded onto it. Thereby a weakening of the material of the sheet 2 occurs near the strands of the lattice (lattice 11), in other words in the regions 13 so that at these positions a "notch effecC occurs when forces, in particular forces acting in the direction of the arrow K, act on the sheet. Figure 6 shows a region in which a mat 12 is laid on the lattice mesh 11. In this case too the sheet 9 is first laid out, the lattice mesh 11 and the matting layer 12 are then laid on this, and subsequently the sheet 10 is extruded onto it. Despite the action of the pressing rollers no weakening occurs near the strands forming the lattice 11 so that the cover is overall less susceptible to the formation of tears near the strands of the lattice mesh 11. Preferably for this purpose the thickness of the mat 12 is such that it is equal to or greater than the thickness of the reinforcing insert in the form of the lattice mesh 11.

Advantageously, it is also possible to use the embodiment example shown in Figures 4 to 6 in combination with the features of the other embodiment examples.

The invention is not limited to the above embodiment examples but can be modified in many ways within the scope of the invention.

CLAIMS 1 1. A tarpaulin-type cover comprising an edge-strengthening band containing holes, characterized in that the holes (3) in the edgestrengthening band (2) are arranged eccentrically in the latter and are displaced towards the edge of the cover (4) adjacent to the edgestrengthening band (2).
2. A tarpaulin-type cover comprising an edge-strengthening band containing holes, characterized in that in the region of the holes (3) the edge-strengthening band (2) is widened towards the region of the cover (1) facing away from the edge of the cover (4) adjacent to the band.
3. A tarpaulin-type cover comprising an edge-strengthening band containing holes according to Claim 2, characterized in that the width of the widened region perpendicular to the longitudinal extent of the edge- strengthening band (2) in the plane of the cover is at least 1.5 times the width of the edge-strengthening band (2) in the region which is not widened.
4. A tarpaulin-type cover comprising an edge-strengthening band containing holes according to Claim 2 or Claim 3, characterized in that the length of the widened region is at least twice the width of the edge- strengthening band (2) measured from the hole (3) to the edge of the edge- strengthening band (2) which faces away from the side edge of the cover (4) adjacent to the band.
5. A tarpaulin-type cover comprising an edge-strengthening band containing holes according to any one of Claims 2 to 4, characterized in that the edge-strengthening band (2) is formed so that at a transition from the unwidened region to the widened region the edge of the band facing away from the edge of the cover defines a wave-like line.
6. A tarpaulin-type cover comprising an edge-strengthening band containing holes, characterized in that the cover (1) in the region of +he edge-strengthening band (2) and a zone adjacent to the latter, facing away from the edge of the cover (4) adjacent to the band, is reinforced by a reinforcing insert (8) moulded in it or on it and attached flush with the cover (1) in the form of deposited material, a lattice, a woven web or a mat.
7. A tarpaulin-type cover comprising an edge-strengthening band containing holes according to Claim 6, characterized in that the reinforcing insert (8) and/or the edge-strengthening band (2) depending on its or their nature is or are formed in accordance with at least one of the characterizing features of Claims I to 5.
8. A tarpaulin-type cover comprising an edge-strengthening-band containing holes, in particular according to Claim 6 or Claim 7, wherein the cover is reinforced over all its surface and consists of two plastic sheets and a reinforcing insert moulded between these in the form of a lattice grid or deposited lattice, characterized in that, at least in the region of the edge-strengthening band (2), and preferably in a wider region, and in particular in regions as characterized in particular in Claims 1 to 7, a mat (12) is inserted between the reinforcing insert (11) and the second plastic sheet (10) covering the latter and is compressed with the sheets (9, 10).
9. A tarpaulin-type cover comprising an edge-strengthening band containing holes according to Claim 8, characterized in that the mat (12) is at least as thick as the reinforcing insert (11).
10. A tarpaulin-type cover substantially as hereinbefore described with reference to the accompanying drawings.