DE102006051641A1 - Rolling bearing for dry-running or lubricated applications, such as food processing, has bearing rings, which are made of stainless steel and rolling body or bearing rings consists of corrosion resistant titanium alloy - Google Patents

Abstract

The rolling bearing has one or two bearing rings (2,3), which are made of stainless steel and have bearing faces for rolling bodies (6), and rolling bodies which are retained in a cage. The rolling body or the bearing rings consists of a corrosion resistant titanium alloy. The rolling body or bearing ring has titanium-6 percent of vanadium-4 percent aluminium, titanium-10 percent of vanadium-2 percent of iron-3 percent of aluminium, titanium-15 percent of vanadium-3 percent of chromium-3 percent aluminum-3 percent or tin or titanium 4.5percent-iron 1.5 percent-Aluminium 6.8 percent-molybdenum.

Description

Description of the invention

roller bearing for dry running or media-lubricated applications

Field of the invention

The The invention relates to a rolling bearing for dry running or media-lubricated applications, with one or two of stainless Steel formed bearing rings with Wälzkörperlaufflächen and several in one Caged Rolling elements.

Background of the invention

In Many application or production areas are rolling bearings with lubricant lubrication no longer usable, for example in the field of food treatment or processing, in the field of pharmacy or vacuum technology. That's why increasingly roller bearing with minimum quantity lubrication, media lubrication over one to be processed Medium or dry rolling bearings required. Especially from the food sector are increasing Requests for absolute lubricant freedom advanced.

So far were for such applications either rolling bearings made of heat-resistant steels or corrosion resistant and heat-resistant steels manufactured, as far as the bearing rings are concerned. The rolling bearings themselves become particularly with dry rolling bearings made of ceramic in spherical or cylindrical shape. In some Applications are the properties of ceramic bearings, such as the high risk of breakage in the case of repeated impact loads, of Disadvantage. About that can out no needle rollers are made of ceramic materials, so for The above uses and conditions are primarily ball bearings Tobe offered. Cylindrical rollers are only with a ratio length: diameter from about 1: 1 manufacturable and available. Also due to the relatively high price, the use is economical often not justifiable.

Summary of the invention

Of the The invention is thus based on the problem of a rolling bearing specify that for dry running or media lubricated applications is suitable, but nevertheless manages without the use of ceramic rolling elements.

to solution this problem is in a rolling bearing provided according to the invention that the rolling elements and / or the bearing ring or rings consist of a corrosion-resistant titanium alloy.

At the Rolling bearing according to the invention are in place of the Keramikwälzkörper each other current components provided, of which at least a part of a high-strength titanium alloy. Titanium alloys are from home made of corrosion resistant. Furthermore, rolling elements, the are made of a titanium alloy, significantly cheaper as the high-priced ceramic rolling elements, so that in total a rolling bearing is obtained, the - at comparable structure with a rolling bearing with ceramic rolling elements - given the same corrosion resistance Clear and high load capacity is cheaper to produce.

The Rolling bearing according to the invention However, it is not limited to the type in which the rolling elements are made the corrosion resistant are high-strength titanium alloy and the rolling element rings made of corrosion-resistant steels, either in a heat treatment can be embroidered such as X20Cr13, or in the context of steelmaking already inherently enriched with nitrogen, such as. Eg X30CrMoN15-1. Also conceivable is an embodiment in which the rolling elements of commercially available corrosion-resistant toughen of the above type, and the bearing rings are made of high strength Titanium alloy exist. These rolling bearings are also for dry running or media-lubricated applications suitable and inexpensive to produce.

are the rolling elements and the bearing rings made of different materials as described, so the consecutive components of the other also not tend for cold welding, this means, the elements show no pronounced Adhesion. This is because the lattice structure is made of the titanium alloy existing components, so for example, the rolling elements, is different than the grid structure Made of a corrosion resistant usual Steel-made components, such as the bearing rings. While the Titanium alloy components have a hexagonal lattice structure, show the components made of corrosion-resistant steel a cubic body-centered lattice structure. This grid difference reduces the tendency for cold welding, the wear resistance elevated clearly.

As described above, an expedient embodiment of the invention is to make the rolling elements and the bearing rings of different materials, but a material is in any case a high-strength titanium alloy. Such a rolling bearing is as described suitable for the applications in question. But sometimes in addition to the suitability for dry-running or medium-lubricated applications also required non-magnetic properties of the bearing. These are not given in a rolling bearing in which a component made of a conventional corrosion-resistant steel. In order to provide a suitable rolling bearing here as well, an alternative to the invention provides for producing both the rolling elements and the bearing rings from a titanium alloy. Titanium alloys are non-magnetic, so they do not interact with an external magnetic field. After all metallic components made of such an alloy are in this invention embodiment, inevitably shows the entire bearing an amagnetic behavior.

As Described initially, the rolling elements are usually in a cage held. This can for example consist of plastic, so that It is inherently non-magnetic and corrosion resistant for many media. But it can also consist of a stainless steel or especially in the case of a completely non-magnetic rolling bearing also be made of a titanium alloy.

The high-strength titanium alloy can be, for example, Ti-6V-Al4, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Al-3Sn or Ti-4.5Fe-1.5Al-6,8Mo or similar, this list is not exhaustive. Can be used all Titanium alloys of the appropriate quality.

The described rolling bearings are for most claims, which are placed on a dry running or medium use suitable. However, especially in dry running special demands on the Hardness of Running layer of a component, so the rolling elements or the bearing rings, provided, sees an appropriate training invention, the rolling elements and / or the bearing ring or rings in a thermochemical heat treatment process enriched with N and / or B in the surface layer and a diffusion layer or a layer system consisting of diffusion and bonding layer with an at least partially substantially covalent bond character train. For This treatment becomes a diffusion layer in the area of the surface layer or a diffusion and bonding layer system that does not produce metallic Bonding character more, but primarily a covalent bond form has, therefore, a ceramic-like character or edge ceramic-like Features. This is done in a thermochemical heat treatment process Nitrogen and / or boron on the surface side diffused. As a result the einiffunierten elements it comes at the edge layer side in the diffusion layer or the layer system consisting of diffusion and bonding layer to form an intermetallic phase, for example Fe2B or FeB. These formed compounds are border-layer-bound, they have a covalent bonding character, unlike the metal, from the rest Rolling elements formed is. As a result, the already low cold welding tendency, in the corresponding design of the rolling bearing with components different materials - through the structural differences already exists, can be further minimized or can at roller bearings, where the rolling elements and the Bearings made of titanium alloy, the cold welding tendency be significantly reduced. Because by the targeted training of this The boundary layer again results in structural differences between the treated bearing component and the untreated bearing component. Although So so the rolling bearing of the invention due to the low or no lubrication a considerable friction caused Energy input in the or the bearing rings or rolling elements is given, the remains covalent bond structure in the area of the rolling elements of which unaffected does not come to a weld.

By the heat treatment, which takes place within the scope of the thermochemical surface treatment, the surface hardness is inevitably increased, they should have at least 650 HV, with the diffusion zone up to to 0.8 mm thick.

The individual components are preferably produced from a cold strip, in particular, the bearing rings also without cutting, for example by deep drawing or extrusion can be produced.

Brief description of the drawings

Further Advantages and details of the invention are described below of exemplary embodiments described with reference to the figures. The figures are schematic Representations and show:

1 a schematic diagram of a rolling bearing according to the invention, and

2 an enlarged detail view in section from the rolling bearing according to 1 ,

Detailed description the drawings

1 shows an inventive rolling bearing 1 , consisting of an outer bearing ring 2 , an inner bearing ring 3 as well as several on the treads 4 . 5 the two bearing rings 2 . 3 current rolling elements 6 in a cage 7 are held, which cage consists for example of a plastic. A correspondingly enlarged off cut out of the rolling bearing 1 out 1 shows in section 2 ,

The bearing rings 2 . 3 consist in the example shown of a corrosion-resistant, possibly also heat-resistant steel with a C content between 0.15-23%, a Cr content between 13-14% and a maximum proportion of Mo and / or V of 0.2% and Proportions of silicon, manganese, sulfur and / or finely stabilizing elements such as Al and Ni, besides optionally further conventional steel constituents and impurities. As this suitable steels z. X20Cr13, which is embroidered in a heat treatment, or the naturally nitrogen-enriched steel X30CrMoN15-1. In the area of treads 4 . 5 Nitration has produced a nitrogen-enriched edge zone to increase the hardness of the basic material or basic structure of the rolling bearing rings 2 . 3 increase to at least 650 HV and the adhesion and wear properties of the treads 4 . 5 to improve. The bearing rings 2 . 3 may be deep-drawn or extruded from a cold-rolled strip or wire.

Also the rolling elements 6 are made of metal using suitable high-strength titanium alloys such as Ti-6V-Al4, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Al-3Sn, or Ti-4,5Fe-1,5Al-6,8Mo can. Every rolling element 6 is subjected to edge zone treatment in a thermochemical diffusion process to form a diffusion-related edge zone 8th form, which can be produced as a pure diffusion layer, or as a layer system consisting of a diffusion layer and a diffusion-related growing bonding layer. As a diffusion element N and / or B is used, optionally other diffusion elements are used, for example, promote the formation of carbides, mixed crystals or intermetallic compounds. As a result of the introduction of nitrogen and / or boron, mixed crystals, etc., form in the surface layer, etc. The diffusion depth or the entire thickness of the surface layer 8th Whether it is pure diffusion layer or a layer system, is in the range of a few microns to a maximum of about 100 microns.

As a result of the diffusion-dependent change in the microstructure or the formation of bonds, there are no more metal bonds in the region of the surface layer, but instead there are covalent bonding conditions. As a result, lie with the rolling elements 6 and the treads 4 . 5 the bearing rings 2 . 3 Face or edge layers of different bonding type. After unlike two opposing, mutually rubbing metal layers in which the friction-related considerable energy input leads to a layer activation and thus to a cold welding, thus therefore a local edge-side local connection, provides in the given here layer system with different edge layers between bearings and bearing rings the friction-induced energy input is not a problem, the covalent binding character is maintained despite the energy input and it comes as a result of bonded electrons not to cold welding.

While at the described embodiment the rolling elements and the bearing rings are made of different materials, it is Of course also conceivable to form a completely non-magnetic bearing both the rolling elements as also the bearing rings of a titanium alloy to ferti gene, wherein in turn, the rolling elements prefer be subjected to the thermochemical diffusion treatment.

All in all The use of a titanium alloy offers the possibility of corrosion-resistant, for the beginning described applications cost-effective to manufacture bearings, as well as in particular with regard to the geometry of the rolling elements - different as in Keramikwälzkörpern - no restriction is given, that is, it can also very thin needle-shaped roller bearing or elongated cylindrical rollers are produced. Also offers the opportunity when using different materials or when using same materials in connection with the thermochemical surface treatment the wear resistance significantly to increase.

1

roller bearing

2

outer bearing ring

3

internal bearing ring

4

treads

5

treads

6

rolling elements

7

Cage

8th

border zone

Claims (4)

Rolling bearings for dry-running or medium-lubricated applications, with one or two bearing rings made of stainless steel with rolling bearing surfaces and a plurality of rolling elements held in a cage, characterized in that the rolling bodies ( 6 ) and / or the bearing ring (s) ( 2 . 3 ) consist of a corrosion-resistant titanium alloy. Rolling bearing according to claim 1 or 2, characterized in that the rolling bodies ( 6 ) and / or the bearing rings ( 2 . 3 ) of Ti-6V-Al4, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Al-3Sn, or Ti-4,5Fe-1,5Al-6,8Mo. Rolling bearing according to claim 1 or 2, characterized in that the rolling bodies ( 6 ) and / or the bearing ring (s) ( 2 . 3 ) one in a thermochemical heat treatment process by enrichment of N and / or B in the surface layer ( 8th ) have a diffusion layer or a layer system consisting of diffusion and bonding layer having an at least partially substantially covalent bond character. Rolling bearing according to claim 3, characterized in that the hardness of the enriched surface layer ( 8th ) is at least 650 HV.