Patent Application
20210381182
The invention relates to a clearing strip for the clearing blade of a snowplow, in particular for use on airfields, having an attachment neck onto which an elongated rubber body is vulcanized, which body has a freely bendable wear section that projects downward, having a wear surface and a wear height.
The challenges regarding the properties of clearing strips for the clearing blade of a snowplow are manifold and depend, above all, on the requirements in the area of use. There is a conflict of goals between rapid clearing, thorough clearing, and gentle clearing. Furthermore, the clearing strips themselves are supposed to have long useful lifetimes, so as to minimize the maintenance effort.
A particular challenge is represented by areas of use having very sensitive surfaces. These include, in particular, airfields at airports as well as historical or valuable ground coverings on market squares or the like. While material damage is a particular threat in the case of the historical or valuable ground coverings, very great safety demands are made on clearing strips used on airfields. Furthermore, rapid clearing is extremely important for adhering to the take-offs and landings of aircraft, which are often closely coordinated. For example, steel clearing strips, in other words clearing strips on which the clearing edge that comes into contact with the surface to be cleared consists entirely or partially of steel, cannot be used due to flying sparks. Known clearing strips having a clearing edge composed of rubber and hard-material bodies composed of ceramic cannot be used, either, since the ceramic is too brittle and small parts that break out represent a hazard on an airfield. Furthermore, the risk exists that the lights recessed into the ground for what are called ground navigation lights could be damaged by the hard-material bodies and therefore fail.
Known rubber strips in which the clearing edge consists only of rubber are also not suitable for use on airfields, because the clearing edge has relatively little ability to slide, i.e. it is blunt. This leads to the result, in particular at higher speeds in interaction with the elasticity of rubber, of bouncing of the clearing strip, and thereby to an insufficient clearing result or an insufficient clearing speed.
Consequently, at present primarily clearing strips composed of a one-piece plastic body are used on airfields. These perform gentle clearing and have a relatively good ability to slide.
However, it is a disadvantage that such clearing strips wear out quickly. The wear is based on the known friction-wear process that occurs in the case of all clearing strips and is particularly intensive in the case of plastic clearing strips. However, a further problem with regard to the useful lifetimes is also based on the fragility of such one-piece plastic clearing strips. The elongated plastic body of the clearing strip is almost entirely inflexible and breaks relatively frequently during use, in particular at the temperatures in the areas of use, which are usually low.
It is therefore the task of the invention, proceeding from a clearing strip of the type mentioned initially, to further develop this strip to the effect that the clearing strip is suitable for areas of use in which the highest demands are made with regard to gentle, rapid, and thorough clearing, and, at the same time, it has the longest possible useful lifetime.
To accomplish this task, the invention proposes, proceeding from a clearing strip of the type mentioned initially, that plastic slide bodies are inserted into the wear section, distributed in it. By means of this measure, the very good wear properties and bending ability of the rubber body are combined with the very good sliding ability of the plastic slide body. The wear section remains movable with regard to the rigid steel attachment neck. Bouncing of the clearing strip at higher speeds is prevented by means of the improved sliding properties resulting from the insertion of the plastic slide bodies. At the same time, particularly gentle clearing is made possible. The rubber body deforms elastically if uneven areas occur during the clearing process, for example caused by ground navigation lights at airports. Also, the plastic slide bodies inserted into the rubber body can escape upward and/or rearward if the clearing strip hits a barrier. Consequently, the clearing strip according to the invention solves the conflict of goals between rapid, thorough, and gentle clearing in areas of use having particularly sensitive surface coverings, in which, furthermore, great safety requirements apply. At the same time, the clearing strip has better wear properties with regard to friction-wear resistance and fragility. Long-term tests with clearing strips according to the invention, in which more rapid, more thorough and more gentle clearing results were achieved, with simultaneously longer useful lifetimes in comparison with purely plastic clearing strips, have confirmed this.
The plastic slide bodies are inserted into the rubber body with material fit, by means of vulcanization. If necessary, bonding agents can also be used, in addition, for the connection.
It is practical if the wear surface has a rubber surface component and a plastic surface component over at least 95% of the wear height. In this way, it is guaranteed that the clearing strip combines the positive properties of pure rubber clearing strips and pure plastic clearing strips, as described above, over its entire useful lifetime. Due to the production process, a thin rubber layer might remain on the wear surface in the case of newly produced clearing strips according to the invention, after the vulcanization process. Furthermore, thin layers can occur, for example, between plastic slide bodies that are arranged in rows, one above the other, in which layers the wear surface has only a rubber surface component. Essentially, however, the clearing strip has both a rubber surface component and a plastic surface component over its entire wear height.
Furthermore, it is practical if the ratio between plastic surface component and rubber surface component is coordinated between the two. By means of this measure, the clearing strips can be further adapted for special requirements. Thus, for example, with a relatively great rubber surface component in areas of use in which the friction-wear resistance of the clearing strip is important, or with a relatively great plastic surface component in areas of use in which particularly good sliding ability is required.
A further development of the invention provides that the ratio between the rubber surface component and the plastic surface component is essentially the same over the entire wear height. Because of the uniform ratio of rubber surface component and plastic surface component, the clearing properties of the clearing strip remain the same over the entire wear height.
It is particularly advantageous if the wear surface has a sandwich-type structure having a front and a rear rubber surface component and a plastic surface component that lies between them. Experiments have shown that such a structure has an extremely positive effect with regard to the clearing result and also with regard to the wear resistance of the clearing strip.
Alternatively to this, it can also be practical if the plastic surface component is arranged in the front in the direction of travel, and the rubber surface component is arranged in the rear in the direction of travel. Because of the plastic surface component in the front, the clearing surface comes into ground contact first with this component, with reference to the direction of travel, and thereby the sliding properties are influenced in particularly advantageous manner.
In areas of use in which the friction-wear resistance is particularly important, it is advantageous if the plastic surface component is arranged in the rear and the rubber surface component is arranged in the front in the direction of travel. Because of the rubber surface component in the front, the clearing surface comes into ground contact first with this component, with reference to the direction of travel, and thereby the friction-wear resistance is influenced in particularly advantageous manner.
A further preferred embodiment of the invention provides that the plastic slide bodies are inserted into the rubber body with shape fit. Shape fit in addition to the material fit anchors the plastic slide bodies in the rubber body even better, so that they are embedded in the rubber body even more securely. The shape fit can be produced by means of design measures during production of the plastic slide bodies. Thus, for example, ribs and saw teeth can be provided on the surface of the plastic slide bodies. During insertion of the plastic slide bodies during the course of vulcanization, shape fit is thereby automatically produced.
The plastic slide bodies can also have a block shape, triangular shape and/or cylindrical shape. The suitable shape can be selected depending on the clearing properties that particularly stand in the foreground in the area of use.
In the following, the invention will be explained in greater detail, using drawings. These show:
a-e show: schematically, clearing strips according to the invention in further embodiments, in a 3D view, in each instance.
In
While in the case of known rubber clearing strips the wear surface has only a relatively blunt rubber component, the wear surface 7 in the case of a clearing strip 1 according to the invention is essentially formed by a rubber surface component 7a and a plastic surface component 7b. Because of the inserted plastic slide bodies 5, the sliding behavior of the clearing strip 1 is massively improved. At the same time, it retains its positive properties with regard to bending ability, elasticity, and friction-wear resistance. While it was known to provide pure rubber clearing strips with hard-material wear bodies, among other things so as to improve the sliding behavior, for decades it was assumed in the technical world that a combination of rubber and plastic could not be implemented. Plastic appeared not to be sufficiently strong for the vulcanization process. Furthermore, it was considered to be impossible to implement a material-fit connection between rubber and plastic. Extensive series of experiments and studies by the applicant have not finally led to a satisfactory result. During the subsequent usage test, the clearing strips 1 according to the invention demonstrate improved sliding ability as compared with pure rubber strips, as well as greater friction-wear resistance and better rupture strength as compared with pure plastic strips.
In this regard, the sandwich-type structure of the clearing strip 1 as shown in
For areas of use in which the sliding ability is particularly important, in other words if clearing is to take place at a relatively high speed, an arrangement of the plastic slide bodies 5 in the rubber body 4 as shown in
For areas of use in which elasticity and friction-wear resistance are particularly important, an arrangement of the plastic slide bodies 5 in the rubber body 4 as shown in
In
It can additionally be advantageous to configure the shape of the plastic slide bodies 5 in such a manner that after the vulcanization process, they are inserted into the rubber body 4 with shape fit, for example by means of a rib-shaped or saw-tooth-shaped surface, not shown.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2018 125 674.4 | Oct 2018 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/077932 | 10/15/2019 | WO | 00 |
