Title of Invention	" LAW FRICTION SLIDING BEARINGS FOR BUILDING CONSTRUCTIONS"
Abstract	This invention affects sliding bearings for the building industry, in particular sliding bearings for bridges, preferably for bridges of magnetic levitation railroads or of high-speed train railways wherein the sliding bearing includes as a sliding bearings material UHMWPE (Ultra High Molecular Weight PolyEthylen).

Full Text

The present invention relates the use as low friction material of a new form of ultra high molecular weight polyethylene (UHMWPE) for sliding bearings for building0020constructions, particularly but not exclusively sliding bearings for bridges, and to low friction sliding bearings manufactured therefrom. The material of the invention evinces particular applicability to and in the manufacture of sliding bearings for the building industry, in particular to gliding bearings for bridges, able to withstand higher loads and/or possessing extended service life. Such bearings find particular use in bridges and under carriage carriers on high speed roads or magnetic levitation railways. Sliding bearings materials for utilization in the building industry and in particular in bridge construction are standardized in the European Norm EN 1337 /Part 2 sliding elements" with regard to their properties and set-up values in design. In accordance with the state of the art, thermoplastics and in particular tefton (PTFE) are also often used for corresponding sliding elements as materials for sliding elements. These materials meet the demands corresponding to the norm. Due to the further technical development in the building industry, and in particular also in the building of bridge structures, however, also the requirements on the material for gliding bearings have increased to a considerable extent in regard to absorbable pressing, resistance to sliding dependent on the environment temperature, on the admissible displacement speed, as well as on glide path and stability against wear that are added up. Notably, a change of these parameters or a break-through beyond certain limit values for these parameters would allow to find different, simpler, and better solutions in design. Particularly high demands are made on materials of sliding bearings, especially in bridge structures of high-speed roads, e.g., high-speed railroads, as well as of magnetic levitation railroads. In bridge structures for such high-speed roads, due to the high speeds of trains going over the bridges, the bearings are often suddenly exposed to high and frequently occurring loads. To meet these demands, it is therefore necessary to manufacture improved materials for sliding bearings. The standards and norms for structural bearings have been laid down by successive Standards of the European Committee for Standardisation. In particular, the two successive norms of June and December, 2000 are considered to set the standards in respect of sliding bearings made from polyethylene. The first of these, European Standard EN 1337 - 1 of June 2000 was followed by an even more demanding European Standard EN 1337 - 2 in December 2000. The present invention is the result of a discovery based on European Standard EN 1337-2 in December 2000 as defined in Appendix D of such Standard whereby the inventors have been successful in establishing a new form of ultra high molecular weight polyethylene (UHMWPE) which has increased efficacy over known forms of UHMWPE. In achieving this, the inventors altered the testing procedure for UHMWPE by amending the test conditions in respect of three essential test parameters. Therefore, it is the object of this invention to provide a sliding bearing or gliding bearing material for it that has an improved profile of properties as compared to gliding bearings materials used to date. In particular, it is necessary to ensure by means of the gliding bearings material a suitable combination of necessary properties for bridge bearings in highspeed roads. This object is solved by using a sliding bearings material in conformity with Patent claim 1 or a sliding bearing in conformity with Patent claim 8. Advantageous arrangements of details are the object of the dependent Patent claims. In conformity with this invention what is suggested as a sliding bearings material in the building industry, especially in bridge sliding materials, preferably for bridges of high-speed roads is the utilization of UHMWPE (Ultra High Molecular Weight PolyEthylen). Namely, based on comprehensive experiments with a variety of sliding bearings materials it was found out that UHMWPE (Ultra High Molecular Weight PolyEthylen) fulfills the necessary properties for utilization in bearings in the building industry, in particular in bridge sliding bearings that meet the aforementioned demands. Due to the very high molecular weight of preferably 3 to 6 million g/mol, the UHMWPE has an extremely high, practically infinitely high melt viscosity and has an outstanding toughness, as well as an excellent stability against cutting and stability against wear. Now it bas been shown that also the other required utilization parameters, such as absorbable surface pressing, resistance to gliding dependent on the environment temperature, admissible displacement speed, as well as admissible gliding path go far beyond what the known gliding bearings materials can achieve for industrial application. In this context, the European Norm EN 1337/ Part 2 is referred to in its currently valid edition and to a corresponding full extent included into the disclosed contents. Namely, it has been shown that it is possible to surpass by far the utilization parameters required in EN 1337/ Part 2 and to be tested in accordance with it both separately and in combination, in particular also at low temperatures. In accordance with this, the utilization of UHMWPE is also in particular foreseen in conformity with the dependent Patent claims for spheres of application where corresponding values occur with regard to surface pressing, to the gliding path, and to the utilization temperatures. In its turn, this offers certain advantages with regard to the design and to the utilization of the sliding bearings, e.g., with regard to the wear of the bearings, to the type of utilization (temperatures) etc. The wear is increased with the product of speed and of pressing, which also has an effect on the service life of the gliding bearings material and hence of the gliding bearing. Preferably the gliding bearings material can be equipped with a filler, in order to improve the dimensional stability. In this respect, in particular glass fibers, glass micro- beads, and ceramics micro- beads have made their proof. In the same manner, it is also possible to add further additives, in order to improve other properties, in particular, to improve the gliding properties. To this end, one utilizes in particular soot, M0S2, or preferably oil. The gliding properties if the gliding bearings material UHMWPE can also be even more improved owing to the fact that in the gliding bearings material that can be available in any form, especially in the form of a plane or curved gliding disk or gliding plate, certain lubrication pockets are foreseen, in order to receive additional lubricants. The gliding bearings material can also have the form of guiding strips. To adjust quite specific defined properties, it furthermore advantageous to mix various UHMWPEs with a different molecular weight in suitable proportions. In a preferred execution example in accordance with the invention, UHMWPE (Ultra High Molecular Weight PolyEthylen) was used as a sliding bearings material in a sliding bearing for a bridge. In this content, the gliding bearing material was taken up in the form of a flat gliding disk by a carrier plate, and in this connection, the gliding disk was up to one half of its sickness sunk-in into the carrier plate. Qualification tests in accordance with the European Norm EN 1337/Part 2 have shown that as compared to PTFE, the UHMWPE allows a surface pressure that is at least by 50% higher and a gliding path that is at least 3 times as long at a 5-fold gliding speed. Furthermore it was found that despite the aforementioned higher loads until the end of the operating time, friction coefficients were measured in accordance with EN 1337/Part 2, whereas these coefficients could also be maintained at environment temperatures until -35°C. According to a preferred execution form for which in accordance with a further aspect of the invention, protection is requested in an independent manner, it has proved to be especially advantageous to combine UHMWPE with lubricating grease on the basis of silicone grease. This combination has turned out to be especially advantageous with regard to the service life and here in particular with regard to the obtainable total gliding path, as well as to the stability against wear. In this context, it was found that the introduction of silicone grease by pressure and/or by rubbing in, as this takes place in particular at the time, when the sliding bearing is worn in, probably brings about a separation of the soapy and of the unctuous ingredients, and in this process the surface layer is favorably modified. Namely, the advantageous gliding properties, or the stability against wear is also observed then, when the lubrication grease has already been removed from the gliding surfaces due to the load. In particular a lithium saponified silicone oil on the basis of methyl phenyl silicone oil has made it proof as a silicone grease. However, it is also conceivable to utilize other silicone greases, if they have one or several of the required properties. In particular, the used silicone greases ought to have a dropping point of > 200° C, in particular of 210° C, in accordance with DIN ISO 2176, a fulling penetration of 20 - 35 mm, in particular of 25 - 30 mm, preferably of 26.5 to 29.5 mm in accordance with DIN ISO 2137, a flow pressure of tion of WE CLAIM: 1. Low friction sliding bearing for building constructions, particularly but not exclusively for bridges, characterized in that the surfaces of said bearing which are in sliding contact are manufactured from ultra high molecular weight polyethylene (UHMWPE), wherein said UHMWPE complies with the friction coefficients in a suitability test as laid down by European Standard EN 1337-2:2000, said suitability test prescribing values for surface pressure, sliding path and/or sliding speed which are larger than the corresponding standard values prescribed, namely a surface pressure greater than 30 MPa, a sliding path greater than 10242 m and a sliding speed greater than 2 mm/s. 2. Low friction sliding bearing as claimed in claim 1, wherein said UHMWPE incorporates therein one or more fillers selected from glass beads, glass micro beads and ceramic micro beads, for improving dimensional stability. 3. Low friction sliding bearing as claimed in claim 1 or 2, wherein, said UHMWPE incorporates one or more additives selected from soot, M0S2 and oil, for improving its sliding properties. 4. Low friction sliding bearing as claimed in any of claims 1 to 3, wherein said UHMWPE forming the surfaces of the bearing in sliding contact is in the form of a plane or curved sliding disk or plate or in the form of guiding strips. 5. Low friction sliding bearing as claimed in any of claims 1 to 4, wherein said surfaces formed from said UHMWPE are provided with a plurality of recesses for receiving lubricants, said recesses comprising lubrication pockets. 6. Low friction sliding bearing as claimed in claim 5, wherein the said lubricant contained in said-recesses is silicone grease. 7. Low friction sliding bearing as claimed in any of claims 4 to 6, wherein said sliding disk or plate is located within a carrier plate into which said sliding disk is sunk up to one half of its depth. 8. Low friction sliding bearing as claimed in any of claims 1 to 7, wherein a film of silicone grease is applied to the surface area of said UHMWPE. 9. Low friction sliding bearing as claimed in claim 8, wherein said silicone grease is incorporated into the surface area of said UHMWPE by pressure or by rubbing it into said surface preferably at the beginning of the operation of said bearing. 10. Low friction sliding bearing as claimed in any of claims 6 to 9, wherein said silicone grease is a lithium saponified silicone oil derived from methyl phenyl silicone oil. 11. Low friction sliding bearing as claimed in any of claims 6 to 10, wherein said silicone grease has: Dropping point: > 200° C in accordance with DIN ISO 2176; Working penetration of 2.0 - 35 mm, in particular 25 - 30 mm, preferably 26.5 to 29.5 mm according to the DIN ISO 2137; Flow pressure of Flow pressure of Oil precipitation of 18 hours according to DIN 51817. 12. Low friction sliding bearings as claimed in any of claims 1 to 11 used for construction of buildings, particularly but not exclusively for construction of bridges.

Documents:

493-delnp-2005-abstract.pdf

493-delnp-2005-claims-(cancelled).pdf

493-delnp-2005-claims.pdf

493-delnp-2005-complete specification (granted).pdf

493-delnp-2005-correspondence-others.pdf

493-delnp-2005-correspondence-po.pdf

493-DELNP-2005-Description (Complete).pdf

493-delnp-2005-form-1.pdf

493-delnp-2005-form-18.pdf

493-delnp-2005-form-2.pdf

493-delnp-2005-form-3.pdf

493-delnp-2005-form-5.pdf

493-delnp-2005-gpa.pdf

493-delnp-2005-pct-210.pdf

493-delnp-2005-pct-409.pdf