DE102013205234A1 - Process for the aftertreatment of burnished bearing components - Google Patents

Abstract

The invention relates to a method for the aftertreatment of steel bearing components (1), which are subjected to a browning treatment to form a browning layer (2) on the bearing components (1). The bearing components (1) are treated with a polishing agent (5) in the area of spots (3) that arise on the browning layer (2) during the browning treatment, which contains a first abrasive and a second abrasive, the first abrasive being less Has hardness than the burnished layer (2) and the second abrasive has a higher hardness than the burnished layer (2).

Description

The invention relates to a method for the after-treatment of bearing components made of steel, which are subjected to the formation of a burnishing layer on the bearing components of a burnishing treatment.

A number of properties of bearing components, such as the corrosion and / or wear behavior, can be improved by suitable burnishing methods, in which an oxide layer is formed on the surface of the bearing components. For example, is from the DE 102007061193 A1 a rolling-loaded component is known, whose surface at least partially has an iron oxide layer of a defined composition. This iron oxide layer has a very fine uniform structure, is very dense and has a high resistance to mechanical and chemical agents. Accordingly, the component has good mechanical and chemical properties in the region of the iron oxide layer. In addition, the component in the region of the iron oxide layer has a low surface energy and good wetting properties with respect to lubricants.

The burnishing of the bearing components is usually done with the help of baths, d. H. Containers filled with chemical solutions into which the bearing components are immersed. During the blackening, the chemicals react with the material of the bearing components and form a burnishing layer in the area of the surface of the bearing components. However, not all reaction products firmly adhere to the surface, forming a slurry layer of reaction product precipitated as solids at the bottom of the container, the thickness of which increases more and more over time. The reaction products may be, for example, iron oxides, iron hydrates or iron hydroxides. If the mud layer has become so thick that the burnishing process is adversely affected in an unacceptable manner, it is necessary to drain the bath and remove the mud. Then the bathroom is recalculated. The draining and refilling of the bathroom requires a production interruption and thus additional costs. In order to keep the additional costs as low as possible and to allow economical operation of the burnishing system, an attempt is made to delay the drainage of the bath as long as possible. In general, the release is waited until the sludge layer has almost reached the immersed in the bath bearing components or their goods carrier. However, as the thickness of the sludge layer increases, there is a risk that sludge is swirled up during burnishing and deposits on the bearing components. In addition, burnishing baths are usually operated at the boiling point, and the active and intensive circulation even at lower sludge levels results in scouring and deposition of reaction products on the bearing components, especially on horizontal surfaces, which allow gravitational deposition. The deposited reaction products bond firmly to the surface of the bearing components and cause dull black to gray spots in which the surface of the bearing components is rough and dull. Due to the not precisely predictable flow conditions in the bath, a reliable prognosis of staining is not possible.

The stains can not subsequently be rubbed off with an oily cloth or with solvents. A chemical removal of stains is also eliminated because the stains and the browning have a very similar chemical behavior. Thus, a chemical stain removal, e.g. B. with acid, remove the browning equally or at least damage. A mechanical removal with metal polish would result in the burnishing at the edges of the stains being polished faster than the stains themselves. The use of abrasive particle-containing pastes involves the risk that unacceptable damage to the blackening may occur and that abrasive particles are being carried to the warehouse made from the bearing component. This can lead to premature failure of the bearing.

The object of the invention is therefore to remove any browning resulting stains without damaging the burnishing layer and the bearing component with reasonable effort.

This object is achieved by the feature combinations of the independent claims.

In the method according to the invention for the after-treatment of bearing components made of steel, which are subjected to a burnishing treatment to form a burnishing layer on the bearing components, the bearing components are treated with a polishing agent in the area of spots which arise on the burnishing layer during the burnishing treatment. The polishing agent contains a first abrasive and a second abrasive, wherein the first abrasive has a lower hardness than the burnishing layer and the second abrasive has a higher hardness than the burnishing layer.

The invention has the advantage that with relatively little effort by bleaching the bearing components resulting stains can be removed reliably and without damage to the burnishing layer and without detriment to the camp. It has been found that the burnishing layer is usually properly formed under the stains. This is due to, that the stains in the initial phase of the burnishing treatment are not formed as closed layers and are also not media-tight in the further course. Particularly advantageous is the invention for the treatment of large bearing rings, z. B. with an outer diameter of up to 2 m, as large bearing rings represent a significant financial value and a rejection as a committee high financial damage would result.

The first abrasive and / or the second abrasive may consist of a granular material. In particular, the first abrasive material can have first abrasive particles of a first particle size and the second abrasive material can have second abrasive particles of a second particle size, wherein the first particle size is greater than the second particle size.

The first particle size may be greater than the layer thickness of the burnishing layer and / or the second particle size may be smaller than the layer thickness of the burnishing layer.

The first abrasive may be contained in the polishing agent with a larger volume fraction than the second abrasive. In particular, the volume fraction of the first abrasive to the volume fraction of the second abrasive can be in the ratio of 3: 1 to 10: 1 to each other.

The invention further relates to a method for the after-treatment of bearing components made of steel, which are subjected to the formation of a burnishing layer on the bearing components of a burnishing treatment. The bearing components are treated with a polishing agent which contains polishing earth and polishing chalk in the area of stains which arise during the burnishing treatment on the burnishing layer.

The polish may further contain soap and / or aliphatic hydrocarbons and / or nonionic surfactants. The polishing earth may comprise aluminum silicate. In particular, the polishing agent may be alkaline.

The polishing agent can be applied to the bearing components or to a first tissue and the first tissue in the area of the spots touching the bearing components are guided. The first tissue holds the polishing agent stationary, so that a relative movement between the polishing agent and the stains can be generated by a movement of the first tissue. In this case, the first fabric can be pressed with a predetermined contact pressure against the bearing components. The contact pressure can be distributed very evenly with the first tissue. Another advantage of using the first fabric is that abraded residues are taken up by the fabric structure and thereby a local increase of the contact pressure can be prevented.

Oil, for example mineral oil, can be added to the polishing agent. As a result, a clumping of the polishing agent can be prevented and its abrasive action can be reduced. The oil can be applied to the bearing components or to the first tissue.

The first fabric can be passed several times over the bearing components. This allows a reliable and gentle removal of the stain. In particular, the first fabric can be guided over the bearing components at least 4 times, in particular at least 6 times. Furthermore, the first tissue can be guided a maximum of 20 times over the bearing components. In particular, the first fabric is guided alternately in mutually opposite directions over the bearing components.

In the context of the method according to the invention, a second tissue without polishing agent can be guided touching the bearing components. As a result, residues of the polishing agent can be removed from the burnishing layer.

The bearing components can be treated after preservation with the polishing agent with preservative, such as preservative oil. In this way, the period in which the bearing components are exposed to a risk of corrosion can be kept very short.

The preservative may be applied to the bearing components or to a third tissue and the third tissue may be passed over the bearing components in a contacting manner.

As a first tissue and / or as a second tissue and / or as a third tissue, a cloth can be used. In particular, a microfiber cloth can be used.

The three-step approach, which uses the first fabric with polish, the second fabric without polish, and the third fabric with a preservative in turn, has the advantage of leaving very little foreign matter and polishing residue on the burnishing layer. Another advantage is that possibly remaining polishing agent does not cause any damage to the bearing component, since the first abrasive is very soft and therefore does not damage hardened bearing components. Although the second abrasive particles are relatively hard, the bearing components also do not damage, since the second particle size is very small. The first, second and third tissue can each be so finely structured that it with naked eye appears and chain and shot are not recognizable.

The invention will be explained below with reference to the embodiment shown in FIGS.

Show it:

1 a bearing component 1 before carrying out the process according to the invention in a schematic representation,

2 a snapshot during the implementation of the method according to the invention in one 1 appropriate representation,

3 another snapshot during the implementation of the method according to the invention in one 1 appropriate representation,

4 another snapshot during the implementation of the method according to the invention in one 1 corresponding representation and

5 the bearing component after performing the method according to the invention in a 1 corresponding representation.

1 shows a bearing component 1 before carrying out the process according to the invention in a schematic representation.

The bearing component 1 is made of steel and may be formed, for example, as a bearing ring or as a rolling element. The bearing component 1 has a burnishing layer in the area of its surface 2 on, by dipping the bearing component 1 was trained in a burnishing bath. The presentation of the 1 refers to a time after removal of the bearing component 1 from the Brünierbad. Depending on the residence time and the conditions in the burnishing bath, the burnishing layer can 2 less than 1 micron or up to 2 microns thick. Details about the burnishing process are for example in the DE 102007061193 A1 disclosed.

Over a partial area of the burnishing layer 2 A stain extends 3 , The spot 3 arises during the blackening by addition of precipitated as solids reaction products that are formed during the burnishing in the black bath, on the surface of the bearing component 1 , The reaction products settle as sludge in the burnishing bath and become, for example, during immersion of the bearing component 1 in the Brünierbad or by the circulation of the boiling Brünierbads whirled up and can then on the bearing component 1 deposit. The deposits fused during the burnishing process adherent with the burnishing layer 2 , The stains created in this way 3 are dull black to gray, dull and rough and can be after the removal of the bearing component 1 Do not remove from the bronzing bath with an oily cloth or with a solvent. Rubbing with an oily rag will only cause the stains 3 something smoothed and appear less dull.

2 shows a snapshot during the implementation of the method according to the invention in one 1 corresponding representation.

In addition to the bearing component 1 is in 2 a first tissue 4 shown. On the first tissue 4 is a polish 5 applied. The polish 5 may comprise a mixture of a first abrasive and a second abrasive consisting of different granular materials. The first abrasive may have first abrasive particles of a first particle size. The second abrasive may comprise second abrasive particles of a second particle size.

As the first particle size, an equivalent diameter can be defined, which is determined on the basis of spherical reference particles. The reference particles each have the same volume as the first abrasive particles, d. H. Each first abrasive particle is assigned a volume-equal reference particle. The equivalent diameter can then be defined as a diameter that is exceeded by only 3% of the reference particles. In an analogous manner, an equivalent diameter can be defined as the second particle size, which is exceeded by only 3% of the reference particles, which each have the same volume as the second abrasive particles.

The first abrasive may have a lower hardness than the burnishing layer 2 exhibit. The second abrasive may have a higher hardness than the burnishing layer 2 exhibit. In addition, the first particle size may have a larger value than the second particle size. With a thickness of the burnishing layer of about 1 .mu.m, the first particle size of the first abrasive can be about 1-2 microns. The second particle size of the second abrasive may be less than about 0.25 μm. Such a small second particle size reduces the lifetime when carried over from the bearing component 1 not made bearing. Furthermore, the volume fraction of the first abrasive in the polishing agent 5 greater than the volume fraction of the second abrasive. In particular, the volume fraction of the first abrasive to the volume fraction of the second abrasive can be in the ratio of 3: 1 to 10: 1 to each other.

As abrasives own in particular materials which have a good oil absorption, since they for use with oil, especially mineral oil-based preservative oil, and which are chemically inert.

As the first abrasive z. As chalk (calcite) or kaolin (aluminum silicate) are used with a Mohs hardness of about 2.5. Aluminum silicate has a high oil absorption and a low abrasive polishing effect. A residue remaining on the bearing component of such a first abrasive material adversely affects the service life of a bearing component 1 not produced warehouse.

As a second abrasive z. As polishing earth (low-calcined aluminum hydroxides or aluminum oxides, especially alpha-Al2O3) can be used in a rather plate-shaped blunt structure with a Mohs hardness of up to 8.5. Aluminum oxide is chemically inert and has a good oil absorption. At a low degree of calcination comparatively small primary crystals and small agglomerations are present. The effective hardness is low and there is a slight breakup of the crystal agglomerates.

The polish 5 may further contain cleaning additives having a corrosion-inhibiting effect, in particular alkaline ammonium oleate and phosphoric acid esters. The overall setting of the polish 5 is alkaline to prevent neutralization reactions with alkaline browning residues or to attack the blackening in the acidic area. The pH is preferably at least 9.

When mixing the polish 5 First, a suspension with a low water content is produced with the abrasives and the cleaning additives. The suspension emulsifiers such. For example, fatty acid amide or diethanolamide added as in the application of the polishing agent 5 Oil is added. Kerosene and an oil content, for example paraffin oil, can be added to the suspension for consistency adjustment before use. Likewise, nonionic surfactants, aliphatic hydrocarbons and soaps can be added to aid in the cleaning action. The polish 5 For example, it may contain 15-30% of polishing clay and polish, 5-15% soaps and aliphatic hydrocarbons and a maximum of 5% nonionic surfactants.

The polish 5 is compatible and miscible with Dewatering Fluid and preservative oil.

To remove the stain 3 becomes the first tissue 4 on which the polish 5 is applied, under slight pressure in the area of the spot 3 against the bearing component 1 pressed and parallel to the burnishing layer 2 moved laterally back and forth. The directions of movement are in 2 indicated by a double arrow. To remove the stain 3 are usually 3 to 10 lateral movements of the first tissue 4 required in both directions indicated by the double arrow. After execution of this movement becomes the first tissue 4 from the burnishing layer 2 lifted and followed by another processing step, based on 3 is explained in more detail.

3 shows a further snapshot while performing the method according to the invention in one 2 corresponding representation.

To carry out the in 3 is shown in the process step of the 2 used first tissues 4 , on the polish 5 is applied against a second tissue 6 exchanged, on which no polish 5 and no other material is applied. With the second tissue 6 is once beyond the area of the burnishing layer 2 wiped, previously with the polish 5 was treated. This is the second tissue 6 with a very low contact pressure against the bearing component 1 pressed. The movement of the second tissue 6 relative to the bearing component 1 is in 3 represented by an arrow. The second tissue 6 takes residues of the polish 5 on, after polishing on the burnishing layer 2 remain. When cleaning the burnishing layer 2 with the second tissue 6 finished, becomes the second tissue 6 from the burnishing layer 2 lifted and followed by another processing step, based on 4 is explained in more detail.

4 shows a further snapshot while performing the method according to the invention in one 3 corresponding representation.

To carry out the in 4 is shown in the process step of the 3 used second tissue 6 against a third tissue 7 exchanged with a preservative 8th , For example, a preservative oil, soaked. The third tissue 7 will be in the area previously with the second tissue 6 was treated with a low contact pressure against the bearing component 1 pressed and laterally over the burnishing layer 2 emotional. This movement is in 4 represented by a double arrow. The third tissue 7 takes any on the burnishing layer 2 remaining residues of the polishing agent 5 and wets the burnishing layer 2 with the preservative 8th , The reached after this process step final state of the bearing component 1 after removing the stain 3 with the inventive method is in 5 shown.

5 shows the bearing component 1 after carrying out the process according to the invention in one 1 corresponding representation.

The previously on the burnishing layer 2 existing stain 3 (please refer 1 ) is completely removed. The burnishing layer 2 is completely intact and thus was not damaged by the inventive method.

In a variant of the method according to the invention, the substances for the treatment of the bearing component 1 additionally or alternatively for application to the first tissue 4 or on the third tissue 7 on the bearing component 1 applied. Accordingly, for carrying out the in 2 illustrated process step polishing agent 5 in the spot 3 be applied. In an analogous manner, for carrying out the in 4 illustrated method step preservative 8th on the burnishing layer 2 be applied.

LIST OF REFERENCE NUMBERS

1

 bearing component

2

 Brünierschicht

3

 spot

4

 first tissue

5

 polish

6

 second tissue

7

 third tissue

8th

 preservative

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007061193 A1 [0002, 0030]

Claims (11)

Process for the aftertreatment of bearing components ( 1 ) of steel used to form a burnishing layer ( 2 ) on the bearing components ( 1 ) are subjected to a burnishing treatment, wherein the bearing components ( 1 ) in the area of spots ( 3 ) during the burnishing treatment on the burnishing layer ( 2 ), with a polishing agent ( 5 ), which contains a first abrasive and a second abrasive, wherein the first abrasive has a lower hardness than the burnishing layer (US Pat. 2 ) and the second abrasive has a higher hardness than the burnishing layer (US Pat. 2 ) having. The method of claim 1, wherein the first abrasive has first abrasive particles of a first particle size and the second abrasive second abrasive particles of a second particle size and wherein the first particle size is greater than the second particle size. Method according to claim 2, wherein the first particle size is greater than the layer thickness of the burnishing layer ( 2 ) and / or the second particle size is smaller than the layer thickness of the burnishing layer ( 2 ). Method according to one of the preceding claims, wherein the first abrasive having a larger volume fraction in the polishing agent ( 5 ) is included as the second abrasive. Process for the aftertreatment of bearing components ( 1 ) of steel used to form a burnishing layer ( 2 ) on the bearing components ( 1 ) are subjected to a burnishing treatment, wherein the bearing components ( 1 ) in the area of spots ( 3 ) during the burnishing treatment on the burnishing layer ( 2 ), with a polishing agent ( 5 ) containing polishing earth and polishing chalk. Method according to one of the preceding claims, wherein the polishing agent ( 5 ) on the bearing components ( 1 ) or on a first tissue ( 4 ) and the first tissue ( 4 ) in the area of the spots ( 3 ) touching the bearing components ( 1 ) to be led. Method according to one of the preceding claims, wherein the polishing agent ( 5 ) Oil is added. Method according to one of claims 6 or 7, wherein the first tissue ( 4 ) several times over the bearing components ( 1 ) to be led. Method according to one of the preceding claims, wherein a second tissue ( 6 ) without polishing agent ( 5 ) touching the bearing components ( 1 ) to be led. Method according to one of the preceding claims, wherein the bearing components ( 1 ) after completion of the treatment with the polishing agent ( 5 ) with preservative ( 8th ) be treated. Process according to claim 10, wherein the preservative ( 8th ) on the bearing components ( 1 ) or on a third tissue ( 7 ) and the third tissue ( 7 ) touching the bearing components ( 1 ) to be led.

Images