DE102010053338A1 - Thrust washer, useful for planetary gear, comprises a washer body that exhibits a surface structure at least in sections, produced by shot peening, and a friction-and wear-reducing layer at least in sections, produced by phosphating - Google Patents

Abstract

Thrust washer for planetary gear, comprises: (i) a washer body that exhibits a surface structure at least in sections, produced by shot peening, and; (ii) a friction-and wear-reducing layer at least in sections, produced by phosphating. INDEPENDENCE CLAIMS are also included for: (1) a planetary gearbox (1) comprising at least one planet gear (5) mounted on at least one planet gear carrier (2), where at least one axially arranged thrust washer is located between the planetary gear and the planet carrier; and (2) producing the thrust washer, comprising (a) at least partially shot peening a prefabricated washer body; and (3) (ii) at least partially coating the at least shot peened area of the washer body, to form the friction-and wear-reducing layer, via phosphating.

Description

Field of the invention

The invention relates to a thrust washer of a planetary gear.

Background of the invention

Thrust washers are known to serve the axial starting of the planetary gear of a planetary gear and to protect the planet and the planet from wear. The planet gear runs with an end face against a contact surface of the thrust washer or disk body. Consequently, the thrust washers are to be seen as a sliding partner for the roller bearings, which are generally roller-mounted in particular via needle rings, and the bearing cages associated with the roller bearing, in order to prevent a friction and wear-intensive shrinkage of the components of the planetary gear.

The thrust washers are typically made of a metallic material such. As non-ferrous metal or hardened steel. It is common practice to form the thrust washers by grinding or coating according to the surrounding components friction.

Depending on the application and stress, however, it often leads to signs of wear and damage to the thrust washers, which can lead equally to wear and damage to the surrounding components such as the planetary gears, planetary carriers, etc. To reduce friction and wear, the thrust surfaces of the thrust washers are additionally lubricated or oiled. However, it is difficult to provide all friction-active surfaces sufficiently with a protective lubricating film, which is why it can lead to wear despite lubrication of the thrust washers up to a total failure of the planetary gear.

Summary of the invention

The invention is therefore based on the problem of specifying an improved in particular with regard to friction and wear discs thrust washer for a planetary gear.

The problem is solved according to the invention by a thrust washer of the type mentioned, which is characterized by a disk body having at least partially a surface structuring produced by shot peening, which is at least partially provided with a layer produced by phosphating friction and wear-reducing layer, characterized.

The thrust washer according to the invention has excellent tribological properties, d. H. in particular low tendency to frictional and wear phenomena, which result from carrying out a shot peening treatment of parts, but preferably the entire disk body in the area of the loaded surfaces, and the subsequent phosphating at least the shot-blasted area. Shot peening or shot peening is one of the methods of surface treatment in which one or more blasting agents are directed at a high speed onto a workpiece surface, whereby by shot peening the surface hardness of the workpiece to be machined, i. H. in the present case of the disk body, in the sense of work hardening or its abrasion resistance can be increased.

Phosphating is a process of surface technology in which by chemical reactions of metallic surfaces with aqueous phosphate solutions, a so-called conversion layer on the surface of the starting material consisting of firmly adhering metal phosphate compounds is formed, which significantly improve the friction and wear properties of the thrust washer altogether. Due to the phosphating preceding shot peening of the disk body is a surface activation, which allows the formation of a solid, well-adherent, fine-grained metal phosphate layer.

In this case, the thrust washer according to the invention has a characteristic surface structuring with dome-shaped ball impressions produced by the shot peening, which can serve as a lubricant retention volume when the thrust washer is lubricated, resulting in excellent emergency running properties of the thrust washer with a low tendency to wear.

The layer formed by the phosphating is preferably a manganese phosphate layer. With the formation of a manganese phosphate layer on the shot-peened wheel body, the best results were obtained with regard to the tribological properties of the thrust washer. Of course, in other cases, other phosphatized layers such as zinc or iron phosphate layers are conceivable.

The layer formed by phosphating preferably has a layer thickness in the range of about 1-8 microns, in particular of about 2-6 microns. In exceptional cases, even thinner or thicker layers are conceivable.

Advantageously, the layer formed by phosphating a roughness value R _A, that is an average arithmetic roughness value of not more than 1.5 micrometers, in particular at most 1 .mu.m. In exceptional cases, deviations upwards are conceivable. Basically, the thrust washer according to the invention or the layer formed by phosphating on a low roughness, which positively influences the excellent tribological properties.

In a development of the invention, the disk body is formed of a metallic material, in particular a hardened steel. In that regard, the disk body has inherently a high hardness, wear resistance and possibly surface quality, which improves the tribological behavior of the thrust washer. The disk body may optionally also be formed of other metallic materials such as non-ferrous or light metals or metal alloys.

The invention also relates to a planetary gear, comprising at least one planet gear mounted in at least one planet carrier, wherein between the planet gear and the planet carrier at least one thrust washer axially arranged between them, as described above, is arranged. The planetary gear is protected by the excellent tribological properties of the thrust washer before caused by the axial shrinkage of the planet or other components associated with the planetary gear damage.

In addition, the present invention relates to a novel manufacturing method for friction and wear improved thrust washers for planetary gear. The improved friction and wear properties result from the at least in sections, but preferably complete implementation of a shot peening treatment of a particular punched from a hardened steel strip or the like, thus prefabricated disk body, which can also be referred to as thrust washer blank, and the subsequent phosphating at least the shot-blasted portion of disk body. By shot peening, it is equally possible to remove after the punching process of the disk body protruding burrs, d. H. conventional methods for punching deburring such as grinding or the like may optionally be at least partially eliminated or shortened in their process duration.

In the case of phosphating, a distinction is generally made between non-layer-forming and layer-forming phosphating, in the first case the metal cations involved in the layer formation originating from the base material and in the second case the layer formation being primarily by metal cations from the phosphate solution. Both types of phosphating are conceivable in the production process according to the invention. The friction and wear-reducing layer produced by the phosphating preferably has a layer thickness in the range of 1-8 μm, in particular 2-6 μm. As mentioned above, surface activation takes place by means of shot peening of the disk body preceding the phosphating, which enables the formation of a solid, well-adhering, fine-grained metal phosphate layer.

Both the shot peening and the phosphating of the disk body can be carried out in several steps, thus gradually. After shot peening and phosphating the disk body is a ready-to-use thrust washer before.

For shot peening, balls with a diameter of about 0.1-0.8 mm, in particular of about 0.2-0.5 mm, are preferably used. The balls can be made of any, in particular metallic, d. H. hard metal materials or ceramics are formed and have a higher hardness than the thrust washer on. In exceptional cases, the balls used for shot peening may also have smaller or larger diameters. It is also conceivable that these deviate from a purely spherical shape and, for example, have at least proportionally an elliptical shape.

In a development of the invention, the shot peening of the disk body takes place in such a way that the disk body subsequently has a mean arithmetic roughness R _A of 0.5-5 μm, in particular in the range of 1-2 μm.

The surface treatment of the shot-blasted starting wheel blank by phosphating is preferably carried out in such a way that the starting wheel blank subsequently has a roughness R _A , ie an average arithmetic roughness value of at most 1.5 μm, in particular at most 1 μm.

Both in terms of the roughness of the disk body after the shot peening and the roughness of the friction and wear-reducing layer formed by phosphating are deviations upward conceivable in exceptional cases.

Short description of the drawing

An embodiment of the invention is illustrated in the drawing and will be described in more detail below. Show it:

1 a schematic sectional view through a planetary gear;

2 a schematic representation of a thrust washer according to an exemplary embodiment;

3 a schematic sectional view of a surface profile of a thrust washer; and

4 a schematic plan view of a section of a surface of a thrust washer.

Detailed description of the drawing

1 shows a schematic sectional view through a planetary gear 1 , which is designed for example as a stepped automatic transmission. The planetary gear 1 includes two substantially radially extending planet carrier 2 . 3 , between which one axially on a planetary pin 4 stored planetary gear 5 extends. Here is the planetary gear 5 by means of a rolling bearing arrangement 6 , consisting of z. B. in a cage 7 recorded cylindrical rolling elements 8th on the planet stud 4 stored. The planet wheel 5 respectively its external toothing 9 engages with the external teeth 10 a coaxially arranged sun gear 11 ,

Between the contact zones 12 , which can also be referred to as a contact surface of the planetary gear 5 and the contact zones facing them 13 . 14 the planet carrier 2 . 3 are thrust washers 15 arranged, which is a friction and wear-intensive axial starting of the planetary gear 5 respectively of the rolling bearing assembly 6 associated cage against the planet carrier 2 . 3 prevent.

A schematic representation of a thrust washer 15 is in 2 shown. The formed as a stamped part thrust washer 15 consists of a metallic material, ie, for example, a hardened steel and was made from a die-cut disk body, wherein the disk body preferably at both end faces, ie in particular to the planetary gear 5 respectively the cage 7 respectively the planet carrier 2 . 3 shot-blasting contacting areas and by phosphating with a friction and wear-reducing layer 16 (see. 3 ), preferably a manganese phosphate layer. Accordingly, the thrust washer 15 conditioned by the layer 16 excellent friction and wear properties, as based on the in the 3 and 4 surface profiles shown will be explained in more detail.

3 shows a schematic sectional view of a surface profile of a thrust washer 15 , Obviously, the surface is strongly contoured and has a characteristic of the shot peening structure consisting essentially of depressions 17 due to the guided on the disk body balls. For shot peening of the disk body, for example, silicon carbide balls having a diameter of about 0.3 mm are used. After shot peening, the disk body has a roughness R _A of approximately 2 μm. The roughness R _{A of} the layer formed by phosphating 16 is about 1 micron.

In the 3 shown, obtained by the shot peening characteristic surface structuring of the thrust washer 15 also leads to excellent lubricant and oil absorption properties, as a lubricant or oil or the like in the dome-like depressions 17 the surface of the thrust washer 15 accumulate and can be held there, resulting in very good running or emergency running properties of the thrust washer from a tribological point of view 15 result.

4 shows a schematic plan view of a section of a surface of a thrust washer 15 , For phosphating the thrust washer 15 A manganese phosphate solution was applied to the shot peened surface of the disk body. Optionally, the disk body was cleaned prior to phosphating. In the 3 The structuring by the shot peening shown likewise causes an activation of the surface of the disk body, so that the growth or the formation of viable crystallization nuclei and thus the deposition of the layer 16 , ie preferably a metallic manganese phosphate layer proceeds favorably, as a result of which a solid, well adhering, fine-grained layer results 16 formed.

LIST OF REFERENCE NUMBERS

1

planetary gear

2

planet

3

planet

4

planet shaft

5

planet

6

roller bearing assembly

7

Cage

8th

rolling elements

9

external teeth

10

external teeth

11

sun

12

contact zone

13

contact zone

14

contact zone

15

thrust washer

16

layer

17

deepening

Claims (10)

Thrust washer of a planetary gear, characterized by a disk body having at least partially a surface structuring produced by shot peening, at least in sections with a through Phosphating produced friction and wear-reducing layer ( 16 ) is provided. Thrust washer according to claim 1, characterized in that the layer formed by the phosphating ( 16 ) is a manganese phosphate layer. Thrust washer according to claim 1 or 2, characterized in that the layer formed by the phosphating ( 16 ) has a layer thickness in the range of 1 to 8 microns, in particular 2 to 6 microns. Thrust washer according to one of the preceding claims, characterized in that the layer formed by the phosphating ( 16 ) has a roughness R _A of at most 1.5 .mu.m, in particular at most 1 .mu.m. Thrust washer according to one of the preceding claims, characterized in that the disk body is formed from a metallic material, in particular a hardened steel. Planetary gear ( 1 ) comprising at least one in at least one planet carrier ( 2 . 3 ) stored planetary gear ( 5 ), between the planetary gear ( 5 ) and the planet carrier ( 2 . 3 ) at least one axially arranged between these thrust washer ( 15 ) is arranged according to one of the preceding claims. A method for producing a thrust washer, in particular the thrust washer according to one of claims 1 to 5, characterized in that a prefabricated disk body is shot peened at least in sections and then at least partially coating at least the shot peened portion of the disk body to form a friction and wear-reducing layer Phosphating is performed. A method according to claim 7, characterized in that balls are used for shot peening with a diameter of about 0.1 to 0.8 mm, in particular from about 0.2 to 0.5 mm. A method according to claim 7 or 8, characterized in that the shot peening of the disk body takes place such that the disk body has a roughness R _A in the range of 0.5 to 5 microns, in particular in the range of 1 to 2 microns. The method of any claims 7 to 9, characterized in that the surface treatment of the peened disk body is carried out by phosphating in such a way that the layer has a roughness value R _A of at most 1.5 micron, especially at most 1 micron.

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