Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K1/00—Making machine elements
  • B21K1/02—Making machine elements balls, rolls, or rollers, e.g. for bearings
• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
  • E01D19/00—Structural or constructional details of bridges
  • E01D19/04—Bearings; Hinges
  • E01D19/042—Mechanical bearings
  • E01D19/043—Roller bearings

Definitions

• the invention relates to a roller bearing for structures, in particular bridge structures, consisting of at least one cylindrical roller, which roll between plane-parallel rolling surfaces of an upper and a lower bearing plate within a limited tome area, in which the tome areas of the rollers have a composite material which by way of a an intermetallic boundary layer connecting method between a base material and a work surface material is produced.
• Roller bearings of this type are known, for example from European patent 0 293 648.
• the stress on such roller bearings mainly consists of high pressure and also of corrosion.
• the pressure load is expressed in the so-called Hertzian pressure; corrosion is mainly caused by weather influences, especially at low temperatures, and by chemical attack e.g. caused by sprayed salt or similar chemicals.
• bearings of this type consist of a composite of a base material that must be easy to weld, for example St 52-3 according to DIN 17 100, with a work surface material that Contains 0.20 to 0.35% C and 12 to 18% (Cr + Mo), for example X 40 Cr 13. Bearings of this type are approved for a Hertzian pressure of 1900 N / mm2 (official).
• roller bearings that can withstand higher loads require both a more targeted choice of material and steel treatment processes adapted to the load conditions, in particular the roller body.
• the invention is based on the new finding that the base material is made of a high-strength, tough heat-treatable steel with a tensile strength of about 1000 N / mm2, a minimum elongation of 10% and a notched impact energy of approx. 50 J should exist, while a highly wear-resistant and corrosion-resistant, hardenable steel is suitable for the material of the work surfaces, preferably X 40 Cr 13, X 105 CrCoMo 18 2 or X 190 Cr VW 18 4. In a modification of this, it is the new one Teaching also possible to use a work hardenable steel, such as X 120 Mn 12 or a comparable material for the working layer.
• An essential part of the teaching according to the invention relates to a method for producing the roller bearing.
• the previously known build-up welding and / or hot rolling can be considered, but preferably diffusion welding, because this method reacts very insensitively to the carbon content of the connected steel materials.
• the process according to the invention prescribes in a first process step, starting from the roll diameter and the roll length on the basis of the formulas 1 and 2 and from the graph in FIG. 1, the greatest shear stress (in N / mm2) and its position (in mm below the working surface) to determine and from this to determine the minimum thickness of the layer of the working surface material for the raw diameter of the roll, which should be at least twice the distance of the maximum shear stress from the working surface, from which the raw diameter of the roll is determined, which is made from a high-strength, tough tempered steel with approximately 1000 N / mm2 tensile strength is produced; 34 CrNiMo 6 steel has proven to be well suited.
• the layer thickness of the worktop material should be on average d / 8 to d / 10, where "d" is the final diameter.
• the further manufacturing process can be designed differently according to the invention, and the procedure to be chosen largely depends on the continuous load requirements of the roller bearing.
• the slightest permanent stresses are likely when the layer is applied from the Provide work surface material by build-up welding or by hot rolling or forging, which is subsequently hardened and tempered.
• the steel X 40 Cr 13 is very suitable for welding or hot rolling (or forging).
• the heat treatment problem here is to carry out an optimal heat treatment because the hardening temperature for the base material is approx. 830 to 860 ° C and 1000 to 1050 ° C for the worktop material, while the tempering for the base material is 540 to 680 ° C and for the worktop material at 100 to 200 ° C should take place. Therefore, it does not seem possible to achieve the best possible temperature control for each of the materials for the heat treatment of the roll that has been completed to this extent. As tests have shown, bearings manufactured in this way can, however, be easily loaded with Hertz pressures of 2400 to 2500 N / mm2, which means an increase of 20 to 25% compared to the prior art.
• roller bearings according to the prior art mentioned at the outset tended to crack and break. This is due to the requirement that the base material be weldable, ie must have a low carbon content; therefore only steels with low tensile strength can be considered. In order to keep the shear stresses reduced within the working layer, it should be quite thick. Thick weld layers can have a variety of defects such as air holes, slag inclusions, shrink defects and the like.
• a roll with a diameter of 130 mm is used from the heat-treatable steel 34 CrNiMo 6 in the quenched and tempered state.
• the work surface layer made of X 190 Cr VW 18 4 with a thickness of 15 mm was applied by diffusion welding and hardened by subsequent heat treatment.
• the described manufacturing procedure is also advantageous for the bearing plates, in which the steel grades X 40 Cr 13 and X 105 CrCoMo 18 2 are preferred. Fully hardened bearing plates made of X 40 Cr 13 can also be paired. Experiments with rollers using the manufacturing method described with a working layer made of 105 CrCoMo 18 2 and hardened bearing plates gave the highest load values of around 3600 N / mm2 Hertzian pressure.
• roller bearings with the structure according to the invention made of the proposed steels and in accordance with the intended production method result in stress ranges of Hertzian pressure compared to the prior art compared to the previously known and used bearings, which are up to 150% higher.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Rolling Contact Bearings (AREA)
• Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
• Heat Treatment Of Articles (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6439070

Family Applications (1)

Country Status (2)

Citations (3)

• 1991
  • 1991-08-24 DE DE19914128166 patent/DE4128166A1/de not_active Withdrawn
• 1992
  • 1992-08-18 EP EP92114041A patent/EP0529476A1/fr not_active Withdrawn

Patent Citations (3)

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