DE102008027764A1 - Cage for antifriction bearing i.e. ball bearing, for use in dentistry, has reinforced composite material composed of epoxy resin and ceramic glass fibers, where ceramic glass fibers are provided in form of yarn, fabric or loose short fiber - Google Patents

Abstract

The cage (3) has a reinforced composite material composed of epoxy resin and ceramic glass fibers. The ceramic glass fibers are provided in the form of a yarn, a fabric or a loose short fiber. The reinforced composite material contains sterilization-firm oil as an additive for controlling a friction value of the cage, where the sterilization-firm oil includes mineral oil, silicone oil, ester oil, synthetic hydrocarbons or by-fluoridated polyetherol. The reinforced composite material is made of fluoropolymer i.e. perfluorinated polymer, containing a solid lubricant.

Description

The The present invention relates to a rolling bearing cage or cage for rolling bearings, in particular Ball bearing whose use in a high-speed ball bearing (speed characteristic n × dm> 1,000,000 mm / min), especially for industrial spindle bearing applications and in the medical field, in particular in dental technology.

in the State of the art are composites as suitable cage materials described on a combination of a cotton, paper or Viscose fabric and a thermosetting plastic based. at The application in spindle ball bearings is as a cage material a cotton-reinforced phenolic resin is very widely used. The composite materials described are characterized by a minimal abrasive wear in high speed applications and additionally have one certain oil storage capacity within the tissue, so they also in applications where a lack of lubrication situation prevails, work very well. In the medical field, in particular in dental technology, are sterilization treatments with saturated Superheated steam at approx. 136 ° C, the material damage for all previously known composite materials have as a consequence.

In DE 10 2004 058 518 A describes a cage that is constructed of cotton fabric and epoxy resin and has an additional lubricating additive with polytetrafluoroethylene. Within this combination of materials, epoxy resin has been used instead of phenolic resin to provide thermoset-resistant thermosetting plastic. However, the tear strength of the cotton fine fabric is significantly reduced after about 100 sterilization cycles, so that this material for applications in the medical field does not have completely satisfactory properties.

Other Combinations of thermoplastic materials in conjunction with Synthetic fibers (eg aramide, glass or carbon fiber) can partly this usual in medical technology treatments without However, in terms of damage the required lifetime values due to abrasive behavior not recommended.

Of the The present invention is therefore based on the object, a cage for a rolling bearing, in particular a ball bearing, from a composite material that undergoes a sterilization treatment can be subjected without the strength of the material significantly to deteriorate, and beyond that an improved Lifespan and suitability for use in high-speed rolling or Ball bearings, especially in the medical field, should have.

These The object is characterized by that in the claims Embodiments solved.

The present invention provides a roller bearing cage, in particular ball bearings, comprising a reinforced composite composed of epoxy resin and ramie fibers or mixed fibers derived therefrom. Ramie fibers are linen-like bast fibers which have a comparatively high density of about 1.50 g / cm ³ . By mixed fibers derived therefrom, those fibers are to be understood which have a content of ramie fibers of at least 80%.

In a preferred embodiment of the present invention Ramie fibers or mixed fibers derived from them are used, those with a quality from Ne 30/1 to Ne 70/1, preferably Ne 40/1 to Ne 60/1 are processed. The inventively used Ramie fibers usually have a fineness strength from 4 to 7 cN / dtex. The inventively used Ramie fibers can be in the shape of a yarn, as well used in the form of a fabric or in the form of loose short fibers become. The use of a yarn of ramie fibers is preferred.

optional The reinforced composite material can be used as an additive to reduce of the coefficient of friction contain at least one sterilization-resistant oil.

Of the Cage according to the invention or the inventively provided Cage material is for high speed use Ball bearings, especially for special spindle bearing applications and in the medical field, in particular in dental technology particularly suitable. As an example of such a rolling bearing a ball bearing can be provided, which is usually an inner ring, an outer ring, balls and a cage includes, wherein the balls move on so-called tracks. The task of a ball bearing cage is generally to prevent the rolling elements from rubbing against each other and at a regular distance from each other being held. Ball bearings with speed characteristics n × dm> 1,000,000 mm / min, the as a spindle bearing in industrial applications or in the medical field Range, especially in dental technology, are either made without covers or covered on one or both sides. For the high-speed applications, however, come for reasons the high ball bearing friction torque no sealing washers, but Covers in the form of cover plates made of metal or plastic for use.

1 shows a ball bearing, constructed of In nenring 2 , a coaxially arranged outer ring 1 , where between inner ring 2 and outer ring 1 the balls 6 are arranged by means of a cage 3 guided in accordance with the present invention. The in 1 described cage 3 can be used as a ball bearing cage, for example as a snap cage in deep groove ball bearings (as in 1 shown) or used as a solid cage in angular contact ball bearings / spindle bearings. He relies either against the outer ring shoulder 7 or against the inner ring shoulder 8th (S. 1 ). The following example is intended to illustrate that the cage within the dental turbine bearing represents the crucial component for the lifetime. Assuming that the outer ring 1 for example, is fixed in a dental turbine handpiece and the inner ring 2 rotates at a speed of about 500,000 min ^-1 , so rotate the balls 6 with about 1,000,000 revolutions / minute around its own axis. The cage is driven by the ball set and has a speed of about 200,000 min ^-1 . In the dental turbine, it is aggravating that the rotor shaft and thus also the bearing points tilt due to a radial load component which is transmitted by the dentist to the drilling tool. The balls run out of the ideal circular path at a certain angle. This means that the balls within the ball set assume different speeds of rotation and thereby alternately transfer tensile and compressive stresses to the individual ball pockets of the cage. With the knowledge that this process takes place at ball speeds of 1,000,000 revolutions / minute, the extraordinary loads for the cage are conceivable. The ball pockets wear in the circumferential direction and this may even lead so far that the cage is cut through the ball set practically in the middle. This process is accelerated by the fact that there is already a lack of lubrication situation in the ball bearing after a very short time. In the medical field, especially in dental turbine bearings, the lubricant, which is located in the ball bearing, is transported by the supply air, which is not only passed into the exhaust duct of the turbine handpiece, but also flows through the two ball bearings, out of the rolling contact. In this case, a cage material that is impregnable generates additional runflat properties.

According to the present invention may optionally be provided to reduce the coefficient of friction as an additive, a sterilization-resistant oil, which is preferably based on mineral oil, silicone oil, ester oil, synthetic hydrocarbons (poly-α-olefins) or perfluorinated polyether oil. Such oils usually have a viscosity in a range of up to 100 mm ² / s at 40 ° C. These sterilization-resistant oils generate run-flat properties after discharge of the lubricant from the bearing interior in order to be able to operate the cage with minimal wear even in the boundary friction region. One skilled in the art will be able to select from the above oils one which satisfies the sterilization resistance requirement. Sterilization in the context of the present invention is to be understood that the oil used for a steam pressure sterilization at about 136 ° C is suitable. Furthermore, intended to reduce the coefficient of friction sterilization-resistant oil should be compatible with the introduced into the rolling or ball bearing lubricating oil or with the base oil of the introduced into the rolling or ball bearing grease. Such sterilization-resistant oils are commercially available. By way of example, Turmotempoil 400-02 VAC, available from Lubcon (example of perfluorinated polyether oil), Nye Synthetic Oil 182S, available from Nye (example of poly-α-olefin), Nye Delicate Machinery Oil 154, available from Nye (example of mineral oil ), or Klübersynth D2-46, available from Klüber (example of ester oil).

Of Another can be used as an additive to reduce the coefficient of friction the above sterilization-resistant oil is a fluoropolymer, preferably a perfluorinated polymer, provided as a solid lubricant become. In the context of the present invention is as a solid lubricant Polytetrafluoroethylene (PTFE) particularly preferred, preferably one such having a molecular weight of 500,000 to 10,000,000 g / mol. Copolymers of polytetrafluoroethylene with other suitable fluorine-containing or suitable non-fluorine-containing monomers which are friction-reducing May also be used.

Under an epoxy resin is understood to be commercially available epoxy resins, the essentially liquid, viscous, glassy substances that are before appropriate processing with suitable hardeners and optionally with solvents or reactive diluents be offset. The epoxy described here may be cold, d. H. at about room temperature, or hot cured be, d. H. at about 80 ° C or more. Harder for the epoxy resin processing or hardening Hardeners based on amine for cold and hot curing or acid anhydride based hardener for the hot curing. A cure without the addition of a Hardener exclusively by heat treatment is however also conceivable.

Harder amine-based include polyfunctional aliphatic amines, in particular Diethylenetriamine, dimethylaminopropylamine, isophoronediamine, 4,4'-diaminodiphenylmethane and the corresponding hydrogenated derivatives thereof, however not limited to this.

Acid anhydride hardeners include di However, carboxylic acid anhydrides such as phthalic anhydride, hexahydro- and tetrahydrophthalic anhydride and their alkyl-substituted derivatives used in the presence of conventional basic catalysts are not limited thereto.

epoxy resins include oligomeric compounds having more than one epoxide group per molecule, preferably two epoxide groups per molecule, which are used for the production of thermosets, or the corresponding thermosets themselves. The conversion of the epoxy resins in thermosets carried out by polyaddition reaction with the above described in the art known hardeners.

In Examples of suitable epoxy resins of the present invention are Reaction products of bisphenol A with epichlorohydrin, o-, m- or p-cresol with epichlorohydrin and phenolic novolacs (i.e., methylol group-free Phenolic resins whose aromatic rings are above methylene groups are linked, which have a molecular weight of about 500 to 5000 g / mol) with epichlorohydrin, but are not limited.

Of the Reinforced composite material may also vary depending on the individual Requirements customary excipients known in the art, Fillers and pigments included.

Of the Proportion of the components used for the formation of the invention, reinforced composite required components is hardened according to the required properties Epoxy resin suitably selected. The proportion (in volume percent) to epoxy or ramie fibers is usually in each case 20 to 60% by volume, preferably in each case 40 to 50% by volume. The low-viscosity oil, if provided, is usually only after the mechanical manufacturing in the cage material stored. The proportion of stored oil is then usually included 0.5 to 6, preferably 1.5 to 3 wt .-%, based on the cage material.

Of the used according to the invention, reinforced Composite comprises ramie fibers, preferably in the Form of a yarn that mechanically strengthens the composite material and wear less. The according to the used in the present invention, reinforced composite has the advantage of good thermal stability up to about 180 ° C and is accordingly for a suitable sterilization treatment well suited. The combination of the composite, d. H. the "fiber reinforced Epoxy resin ", gives the cage material the property of even with insufficient lubrication only slightly abrasive too wear out, in contrast to those in medical technology widespread cage materials polyimide (trade name: Vespel (Dupont), Meldin (Saint-Gobain), Sintimid (Ensinger)), Polyamideimide (trade name: Torlon (Solvay Advanced Polymers)) and polyetheretherketone (trade name: Tecapeek (Ensinger)).

1

outer ring

2

inner ring

3

Rolling bearing cage (in particular ball bearing cage)

4

cover disc

5

snap ring

6

roll

7

Outer ring shoulder

8th

Inner ring shoulder

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004058518 A [0003]

Claims (8)

Cage for a rolling bearing, in particular a ball bearing, which reinforced one Composite comprising of epoxy resin and ramie fibers or thereof derived mixed fibers is constructed. Cage according to claim 1, wherein ramie fibers or derived therefrom mixed fibers are used, with a quality from Ne 30/1 to Ne 70/1 are processed. Cage according to claim 1 or 2, wherein the Ramie fibers or mixed fibers derived therefrom in the form of a Yarn, a fabric or in the form of loose short fibers. Cage according to one of the preceding claims 1 to 3, wherein the reinforced composite material as an additive at least one sterilization-resistant oil to reduce the coefficient of friction contains. A cage according to claim 4, wherein the sterilization-resistant oil on mineral oil, silicone oil, ester oil, synthetic Hydrocarbons or perfluorinated polyether oil based. Cage according to one of the preceding claims 1 to 5, wherein the proportion in volume percent of epoxy or ramie fibers each 20 to 60 vol .-%, and wherein the proportion of oil, if present, in an amount of from 0.5% to 6% by weight, based on the cage material, is present. Cage according to one of the preceding claims 4 to 6, wherein the reinforced composite further than Solid lubricant is a fluoropolymer, preferably a perfluorinated Polymer, contains. Use of a cage according to one of the claims 1 to 7 in a high-speed ball bearing with a speed characteristic n × dm> 1,000,000 mm / min, especially for industrial spindle bearing applications and in the medical field, in particular in dental technology.