DK3246509T3 - Increase - Google Patents

Description

It has been known for long that steps of ladders should be designed such that the user of the ladder can safely stand on the ladder even in unfavorable situations.

Basically, this applies to all types of ladder, i.e. both ladders with rungs and ladders with steps. It has been known for long to provide the steps of ladders with an anti-slip pad which is clipped on or may be glued on. An example of such a ladder may be seen from DE 82 09 895 U1, wherein very high slip resistance is created by a rubber mat attached to the tread surface.

Another example of a ladder step secured with a non-slip step can be found in US 6 994 185 B1. Herein, a V-shaped clip element 20 may be clipped onto a triangular ladder stage 2. An upholstery element is attached to the clip element. It is covered with a cover element 50, which has anti-slip properties. These well-known solutions are comparatively prone to wear, especially in harsh environments. After all, considerable pressures, but also shearing forces, are exerted on the surface of the step when stepping on the ladder. In addition, especially with clipped-on profiles, there is the risk for the step support to be accidentally removed from the step by bumping against the direction of the clip, so that stable hold is no longer provided.

Furthermore, it has also become known that steps of ladders are metal-formed and that slip resistance is ensured by suitable profiling. This is exemplified in the solution known from DE 20 2004 002 872 U1. DE 200 10 298 U1 shows a ladder, wherein the tread surface of the rungs is divided. A first portion of the tread surface has tread ribs facing upwards and a second portion has an arched plastic insert also comprising tread ribs.

However, all the solutions proposed so far suffer from certain drawbacks. Apart from the above-mentioned durability, slip resistance is not guaranteed in all environments. In particular, muddy environments should be mentioned, but also oil or oily surfaces. In addition, depending on the design of the anti-slip surface used so far, there is a risk for the anti-slip surface to solely be slip-resistant in one horizontal direction but not in the other direction.

Contrary to this, the object of the invention is to provide a ladder, which is more durable, inexpensive to manufacture, but nevertheless providing the slip resistance desired according to the standard even in very different, unfavorable environments.

According to the invention, this object will be solved by claim 1. Advantageous embodiments will arise from the subclaims.

According to the invention, a plastic profile having anti-slip properties is combined with a specific tread surface of the step having embossments, in particular apertures in the step of a ladder according to the invention. Typically, embossments comprising apertures have the advantage that the surface adjacent to the apertures is sharp-edged due to the embossment mechanism. The apertures are generally designed as circular or hexagonal cut-outs, for example.

According to the invention, the plastic profile is provided with a flat surface free of curvature, which is provided with sharp-pointed grains. The grains strongly interact with the sole of a user's shoe, so that the protrusions of the sole's profile first rest on the grain tips and the sharp-edged grain tips then penetrate the sole.

This ensures secure hold even if the surface of the step or rung is daubed with oil.

Specifically, slip resistance is also provided in the lateral direction, as the sharp-edged teeth of the grains are randomly distributed so that some of the teeth extend transversely to the longitudinal direction of the steps and some extend in the longitudinal direction of the steps.

Preferably, at least some of the sharp-edged grains have sharp angles, i.e. angles of less than 90 degrees, such that the respective sharp edges face upwards.

In this context, "facing upwards" is to be understood to mean that the sharp edges protrude from the surrounding surface of the support layer, for example the synthetic resin layer, i.e. they are exposed.

Preferably, the sharp edges with their axes extend at an angle of less than 45 degrees to the vertical.

In this approach, slip resistance is independent of the axis, which means considerable improvement over corrugations which, for example, are slip-resistant when the environment is exposed to oil in the direction of one axis, but are extremely slippery in the other horizontal axis direction.

According to the invention, the anti-slip mechanism is designed as an arrangement of sharp-edged grains embedded in the plastic material. The height of the sharp-edged grains corresponds to the height of the apertures at their upper edge. On the one hand, arranging the apertures and, on the other hand, arranging the surfaces of the grains adjacent and next to each other ensures that the sole of the user will always be at last partially in contact with the two anti-slip elements, and especially will be in contact therewith while being in a loaded condition.

Combination of these features results in a surprisingly safe anti-slip effect, even under very different environmental conditions and corresponding soiling of the user's soles, such as slush, mud, products containing tar and oil, soapy water and other demanding sliding environments.

Surprisingly, this results in slip resistance which is significantly improved compared to that which would be presumed to be obtained when using a combination of sharp-edged embossments and sharp-edged grains: apparently, the sharp-edged grains have a multidirectional fixing effect when hitting and penetrating the sole of a user such that even with smooth soles, the sharp edges of the embossments will be allowed to penetrate the sole of the user. The grains are retained in the quite thin support layer, while the plastic profile itself is always free of grains.

According to the invention, for example, it is provided for mud or earth deposits to be partially pushed through the apertures in the step surface so that contact of the antislip ring at the top of the aperture, which is sharp-edged, with the sole of the user is ensured. This is particularly true when the user's sole is profiled, because in this case, the embossment typically pushes into grooves or recesses of the sole, thus further improving the stability.

Contrary to this, the sharp-edged grains protruding from the surface of the plastic profile pass through and cut through a layer of soiling film which might be applied to the step by the user's shoes. Even if it is oil or, for example, soapy water, safe contact with the user's shoes is assured as the sharp edges become at least partially engaged into a plastic sole of the user's shoes, thus ensuring safe anchoring.

The grains according to the invention can protrude from the plastic surface up to one millimeter. However, they are embedded therein, for example, with half their height to ensure secure anchoring. Preferably, the surface structure of the grains is irregular and randomly distributed, and the burrs and serrations of the grains result in improved slip resistance.

According to the invention, the plastic profile extends over a corresponding recess in the surface of the step, above a step tube which laterally supports the step on the spars. Preferably, the plastic profile is slightly wider than the recess and rests on the tread surface. The support height essentially corresponds to the height of the embossments, so that the surface of the profile and the upper side of the embossments are at the same height.

In order to ensure safe support of the plastic profile, latching tongues are provided, the projections of which facing outwards, i.e. in the forward or backward direction, in relation to the step, and engaging under the tread surface of the step. The latching tongues can bounce inwards, thus allowing the plastic profile to snap into the recess.

Due to the recess being overlapping and extensive covering, there is little tendency of soiling below the plastic profile.

Preferably, the plastic profile is arranged in a certain clearance above the tube. When load is applied to the plastic profile, it slightly bends while complying with the curvature of the user's sole until it abuts the tube. This ensures that a large area of contact between the sole and the plastic profile is possible without too much bending or even loosening the plastic profile.

Preferably, the apertures extend in the rear region of the step. Typically, the front portion of the shoe is the one to be most muddy, so that this portion is best suited for providing stability due to the breakthrough and the push-through functions described above.

As it is well known, the depth of the step is chosen such that it is significantly shorter than the length of a shoe, for example 12 cm. From the middle of the step to the beginning of the second seventh of the step depth, the plastic profile according to the invention extends with the sharp-edged grains on the top.

Preferably, the plastic profile is flocked with the sharp-edged grains, which are pressed into the plastic profile by reheating, making the plastic viscous, thus retaining the grains therein. Before this is done, the surface of the plastic profile may be provided with a layer of adhesive not yet being cured and contacting the sharp-edged grains at the bottom and partially being pressed into the grain accommodation by the grains, such that the tips of the grains do not come into contact with the adhesive layer.

It is to be understood that the plastic profile, including the optional adhesive layer, is sufficiently temperature-resistant in the working region of the ladders. Herein, the preferred working range is -20 0 Celsius to +50 0 Celsius, wherein it is understood that up and down adjustments may be made by selecting suitable plastics and adhesives.

Instead of using the protruding latching tongues of the plastic profile, fastening pins or tongues may as well be provided which engage beneath the tread surface of the step from below. In any case, the flange indicating the tread surface forming the recess is surrounded in a U-shaped manner by the plastic profile which includes the corresponding locking projection.

Preferably, the tube, which can be designed as a rounded square tube, for example, laterally extends beyond the step, so that it passes through the respective spars of the ladder and is crimped thereto in a manner known per se.

In an advantageous embodiment, the step is provided with a rounded shin protection apron. In a modified embodiment, the plastic profile is extended beyond the shin protection apron in the manner of a cover and engages behind it.

The embossments according to the invention essentially extend conically and preferably ending in sharp-edged apertures. Alternatively, the embossment may also be ground off manually, which also results in sharp edges that are particularly suitable for providing stability. According to the invention it is provided for the step to at least comply with the adhesion safety class R 12 and particularly preferred the adhesion safety class R 13. This does not only apply to dry environments, so that the achievable class is R 13B or even R 13C.

Due to the large surface apertures, a comparatively large displacement volumes are also available.

Further advantages, details and features will arise from the following description of an exemplary embodiment of the invention, while reference will be made to the drawing, wherein:

Fig. 1 is a cross section across a ladder according to the invention, i.e. the respective step, in a plane;

Fig. 2 is a cross section according to Fig. 1, but in another plane;

Fig. 3 is a top view of the step of Fig. 1;

Fig. 4 is a perspective view of the step of Fig. 1;

Fig. 5 is a detailed enlargement of a portion of the step according to the following figures; and

Fig. 6 is a cross section according to Fig. 2, but using an improved resolution.

The ladder according to the invention comprises two spars not shown between which a step or rung extends. In the case of the exemplary embodiment shown herein, it is a step 10, which is shown in the cross-section in Fig. 1. Step 10 comprises a tread surface 12 which is profiled in a specific manner.

In the example shown, step 10 is essentially made of metal, for example light metal, such as aluminum. The step surface 12 is divided, and a first portion, the rear portion of the ladder, i.e. the portion facing away from the user, is provided with embossments, wherein three embossments 14, 16 and 18 may be seen in Fig. 1.

The embossments are configured such that raised areas are formed around the embossments. The continuous metal of step 10, which may be designed as an extruded profile, for example, is machined from below with suitable embossment tools such that the embossments protrude from the tread surface 12.

Preferably, the embossments 14 to 18 have apertures 20, 22 and 24, which extend centrally in the embossments 14 to 18. The apertures 20 and 24 are surrounded by sloping conical flanks of the embossments. The aperture 20 and the aperture 24 are surrounded by an annular surface 26 which is flat and preferably ends with a sharp edge at the aperture 20 and also with a sharp edge at the surrounding flank of the embossment 14.

Preferably, the apertures 20 and 22 are produced by a punching movement from the bottom to the top, such that a burr is created inside the annular surface 26 by the punching process. This is at least partially removed to avoid injury to the user, but it is also possible to leave a burr stump, which then obliquely protrudes upwards and inwards in relation to aperture 20, to further improve stability.

Preferably, the extrusion profile of step 10 is first produced by extrusion and then cut to the desired length, which corresponds to the width of the step, followed by the embossments 14 to 18 and apertures 20 to 24.

In an alternative embodiment, it is provided to operate an embossment/punching tool next to the extrusion press during extrusion, which comprises an embossment punching drum, the step extending between said embossment punching drum and a counterpressure drum. This means that both apertures and embossments are produced in one run during the extrusion process.

In the preferred embodiment, the embossments are produced such that they surround the apertures. It is also possible, however, to alternatively provide embossments which are free of apertures and which taper, for example, into tips which also have good adhesive properties.

However, apertures, including the non-oblique aperture 22, also make it possible to remove dirt, which then does not fall onto the next step as the ladder is slightly inclined, but onto the substrate, so that contamination of the ladder itself is minimized. In addition, the apertures allow provision of a sharp annular edge 28, which is arranged at the maximum height of the tread surface 12, resulting in improvement of stability when, for example, plastic shoes are used by the user.

According to the invention, it is essential for the stability in the longitudinal direction of the step and the stability in the transverse direction of the step to be the same. This object may be achieved by realization of circular annular edges 28 on the protruding apertures, whereas it is understood that any other round or angular design of the aperture may also be used, even without destroying the desired effect of the stability being direction-independent.

Following the first portion of the step surface 12, a second portion is provided. This extends in front of the first portion, thus being closer to the user of the step when climbing the step. The second portion comprises a tube 40 which has a load-bearing function and is anchored at the ends in the ladder spars. The tube is designed as a slightly inclined and rounded square tube and is produced in the usual way during the extrusion process of the step. An inclined supporting flank 42 supports the first portion of the tread surface 12 and extends diagonally upwards/backwards at an angle of approximately 45 degrees from tube 40. A second supporting flank 44 extends obliquely forwards/upwards at an almost right angle to the first supporting flank 42. The second supporting flank 44 ends in a front portion 46 of the step surface 12. At the opposite end of the front portion 46, an apron 48 is provided which extends obliquely forwards/downwards and is convex. The apron 48 simultaneously is rounded shin-protectively and ends in a bulge 50. A plastic profile 52 is arranged above the tube 40 in the second portion of the tread surface 12 according to the invention. It covers a recess 54, which is also formed above the pipe 40. The recess 54 is limited by a front support flange 56 and a rear support flange 58. The front support flange 56 is attached to the front portion 46 of the step surface 12 and essentially extends horizontally to the rear. In contrast, the rear support flange 58 is attached to the first portion of the step surface 12 and essentially extends horizontally to the front. The two support flanges 56 and 58 are thus facing to each other enabling a double function for bearing of the plastic profile 52.

On the one hand, end flanges 60 and 62 of the plastic profile 52 each rest on support flanges 56 and 58. On the other hand, the support flanges 56 and 58 are engaged by latching tongues 64 and 66, wherein the front latching tongue 64 on the front support flange 56 is facing forwards and the rear latching tongue 66 on the rear support flange 58 is facing backwards. In this respect, the plastic profile 52 surrounds the ends of the support flanges 56 and 58 in an essentially U-shaped manner. It is firmly retained thereto and may easily be mounted by engaging the latching tongues.

Covering the support flanges 56 and 58 by the end flanges 60 and 62, which are made of plastic, in combination with the essentially U-shaped course of the plastic profile 52 around the front edges of the support flanges 56 and 58 results in moisture-tight sealing of the recess 54.

The plastic profile 52 has a flat surface. This means lack of curvature, while, in detail, it is by no means completely even. It rather comprises sharp-edged grains on the top side thereof, which are embedded therein and protruding from the plastic profile surface. The grains are securely anchored in the surface of the plastic material, but protrude sharply.

The extension of the plastic profile, both in depth and in width, essentially corresponds to the extension of the area of the embossments 14 to 18. This means that essentially there are areas of the same size on the tread surface 12 which together create the desired stability, with different areas of the tread surface 12 acting more strongly than others, depending on the type of soiling.

For example, if the ladder environment is oil-polluted, and oil adheres to the user's shoes accordingly, the sharp-edged grains in the area of the plastic profile 52 will adhere very well, so it is not important whether the first portion of the step surface is less suitable for providing adhesion and stability in oil-polluted and tar-polluted environments.

Surprisingly, the combination of the surface features according to the invention ensures stability of the user to be guaranteed even with very heavy and very different soiling.

This means that the ladder according to the invention can achieve the stability class R13B.

Fig. 2 shows a cross section of a step 10 at a different position, namely position B according to Fig. 3. The section of Fig. 1, on the other hand, is for position A.

As may be seen from Fig. 2, in this position the center embossment 70 is cut, while the front and rear embossment 14 and 18 are cut according to Fig. 1. As may be seen more clearly in Fig. 4, for example, embossment 70 with the associated aperture 72 extending adjacent to it, i.e. in front of and behind it, simple apertures 74 and 76. They have no or almost no adhesive function, but are to remove dirt. This is particularly advantageous because dirt that does not get into the apertures 20 and 24 could otherwise easily remain on the tread surface 12. According to Fig. 1 it is discharged at the aperture 22 and according to Fig. 2 at the apertures 74 and 76.

In an advantageous embodiment, the apertures may even be slightly lowered, i.e. negatively embossed, which further improves the structure.

As it may be seen from Fig. 2, the plastic profile 52 extends in a small distance above the tube 40. The distance is approximately half the thickness of the plastic profile. When contacting step 10, the plastic profile 52 can deform a little, as viewed from the tread surface 12, in a concave direction. This enables minimal counter-curvature which corresponds to the low curvature of soles of shoes and further improves stability due to the large surface area of the system.

According to the invention, it is advantageous for the plastic profile 52 on the step surface 12 to have a straight design or, if necessary, a slightly inwardly curved design, which occurs in particular when load is applied to the step.

As it may also be seen from Fig. 2, the front portion 46 of the step surface 12 may also be provided with a profile 80 in any suitable manner.

It is to be understood that a set of embossments including apertures could also be provided, if necessary.

Fig. 3 shows that the tube 40 laterally projects beyond stage 10. The tube 40 is inserted into the cross beams of the ladder as described above and flanged at the ends in the usual way to ensure the strength of the ladder.

Step 10 ends at its rear end in bevels 82 and 84, reducing the risk of injury from sharp-edged areas of the step.

Fig. 3 and Fig. 4 show that step 10 similarly extends with its tread surface 12 across the entire width, and comprising a first portion with embossments 14 to 18 and a second portion with the plastic profile 52. The front portion 46 is connected to the plastic profile 52 to the front and the apron 48 is connected thereto.

Fig. 5 shows a detail of step 10. Flerein, the same reference numbers as in the other figures indicate the same parts. It may be seen that the latching tongues 64 and 66 are in contact with the support flanges 42 and 44. In addition to supporting the end flanges 60 and 62 on the support flanges 56 and 58, this also supports the plastic profile 52 on the step.

This may also be seen in Fig. 6. In addition, Fig. 6 shows grains 90, which are embedded in the top surface of the plastic profile 52. For reasons of simplicity, those grains are not shown in the other figures.

Claims (13)

A ladder, with two transverse supports, between which extends a step or groove having a tread surface on which the tread surface is divided, and a first part of the tread surface (12) has upwardly facing embossments (14, 18, 70), surrounding breakthroughs (20, 24, 72), and another portion having a plastic profile (52) which is anchored in or on the step or groove and having anti-slip equipment, and wherein the plastic profile (52) has a flat, vault-free surface wherein the planar surface is pierced by sharp-cut grains (90) which are attached to or protruding therefrom and that the plastic profile (52) extends above a tube (40) supporting the step (10) or is part of the sprout. Ladder according to the preceding claim, characterized in that the plastic profile (52) has a support layer, especially of synthetic resin, into which the grains (90) are embedded. Ladder according to one of the preceding claims, characterized in that the flat surface of the plastic profile (52) is formed at the same height level as the surface of at least part of the breakthroughs (20, 24, 72). Ladder according to one of the preceding claims, characterized in that part of the breakthroughs (20, 24, 72) is formed in or on the embossments (14,18, 70) and another part of the breakthroughs (22, 74, 76) is formed in the planar tread surface. Ladder according to one of the preceding claims, characterized in that the plastic profile (52) is accommodated partially recessed in the step or groove, and with respect to its engagement tongues (64, 66) lies at least partially on the tread surface (12), step (10) or spreader and here supported. Ladder according to one of the preceding claims, characterized in that the plastic profile (52) is supported by a tube (40) which extends below the plane of the plastic profile (52) and that the plastic profile (52) in its central center extending substantially above the highest point of the tube (40) and unstressed at a distance of between 0.5 mm and 5 mm, whereby the plastic profile (52) can be bent at this extent with load and then has a concave surface. Ladder according to one of the preceding claims, characterized in that the plastic profile (52) on its front and / or back side is recessed at least partially in the tread surface (12) with a flange (60, 62). Ladder according to one of the preceding claims, characterized in that the step (10) or the spreader extends beyond the plastic profile (52) on both sides up to the transverse supports of the ladder. Ladder according to one of the preceding claims, characterized in that the step or groove has a shin-friendly rounded spherical skirt (48) and that the plastic profile (52) begins at a location which is particularly slightly spaced from the step or the front of the sprayer on which the skirt (48) is formed is particularly preferred at 3% to 30% of the depth of the step. Ladder according to one of the preceding claims, characterized in that the breakthroughs (20, 24) are at least partially, especially by half, provided in embossments (14, 18, 70) which extend substantially cone-shaped towards the tread surface and projecting from it. Ladder according to one of the preceding claims, characterized in that the embossings, in particular the breakthroughs (20, 74, 76), extend between the tread surface (12) and the back of the step or groove, especially over a depth which substantially corresponds to to the depth of the plastic profile and especially preferably to a depth of between 50% and 200% of the depth of the plastic profile (52). Ladder according to one of the preceding claims, characterized in that the breakthroughs (20, 74, 76) are each surrounded by an elevated and sharp-edged ring edge (28) projecting from the tread surface (12). Ladder according to one of the preceding claims, characterized in that the ladder has a step which, in the transverse direction, ie in the direction between the transverse supports, and in addition in the direction towards its depth, corresponds to the standard DIN 51130 for slip inhibition with the slip class R13.