METHOD FOR PRODUCING A SLIDING SURFACE ON A MACHINE ELEMENT

Abstract

The invention relates to a method for producing a sliding surface on a machine element, in particular a cam follower, wherein the machine element is first provided with a coating on at least part of the surface of the machine element, into which coating a surface structure is then introduced by laser structuring. In order to be able to introduce a surface structure that does not penetrate the coating even in the case of low layer thicknesses (s1) of the coating, the introduction of the surface structure is performed by laser interference structuring.

Claims

1. A method for producing a sliding surface on a machine element, wherein the sliding surface of the machine element is provided for sliding use in contact with at least one additional machine element that is adapted to slide over the sliding surface in a sliding direction (GR), the method comprising: providing the machine element on at least one part of a surface thereof initially with a coating, forming a surface structure thereon by laser interference structuring, such that the formed surface structure when viewed perpendicular to a coating surface of the coating, comprises a number of closed structure elements.

2. The method according to claim 1, wherein each said closed structure, viewed perpendicular to the coating surface, is constructed in a surface extent of maximum 10% of the sliding surface.

3. The method according to claim 1, further comprising forming the closed structure elements in a linear construction as linear sections or point-shaped as cavities.

4. The method according to claim 1, wherein the coating surface is divided into two halves that extend parallel to the sliding direction (GR) by a virtual center line and the method further comprises orienting said closed structure elements in the form of linear sections at an angle Y≠0 relative to the virtual center line.

5. The method according to claim 4, further comprising forming every two of said linear structure elements in a V-shaped structure, with a tip of said V-shaped structure arranged pointing in the sliding direction (GR).

6. The method according to claim 1, wherein a ratio of a structure depth (s2) of the formed surface structure to a layer thickness (s1) of the coating is 0.5.

7. The method according to claim 1, wherein a CrNi layer or a layer made from amorphous carbon is deposited as the coating.

8. The method according to claim 1, wherein the sliding surface is a surface of a cam follower.

9. The method according to claim 1, wherein the surface structure has a non-uniform construction.

10. The method according to claim 1, wherein a number of the structure elements of the surface structure is greater in areas of the sliding surface the higher a sliding speed of the at least one additional machine element is in said area of the sliding surface.

11. A machine element comprising at least one sliding surface produced according to the method of claim 1.

12. The machine element according to claim 11, wherein the coating of the at least one sliding surface has a layer thickness (s1) of 0.05 to 6 μm in which the surface structure is formed with a structure depth (s2) of 0.15 to 0.4 μm.

13. A sliding contact comprising a machine element according to claim 1 and at least one additional machine element, wherein the sliding surface of the machine element is provided for sliding use in contact with the at least one additional machine element, and the at least one additional machine element is provided for sliding over the sliding surface in a sliding direction (GR), and the sliding surface is provided with an overall liquid lubricant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is not limited to the specified combination of features of the main claim or the claims dependent on this main claim. It is also possible to combine individual features, also those that emerge from the claims, the following description of a preferred embodiment of the invention, or directly from the drawing. The references in the claims to the drawing through the use of reference symbols should not limit the scope of protection of the claims. Shown are:

[0028] FIG. 1 a machine element in a section diagram, and

[0029] FIG. 2 a three-dimensional view of a machine element in the form of a rocker arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] FIG. 1 shows a part of a machine element 1 in a section diagram, wherein this machine element 1 is a cam follower, for example, a bucket tappet, a rocker arm, or the like. On its surface 2, the machine element 1 is equipped with a sliding surface 3 for contact with an additional machine element not shown here, wherein for forming the sliding surface 3, initially a coating 4 was deposited on the surface 2.

[0031] In the present case, the coating 4 that can be a chrome-nickel layer or also a layer made from amorphous carbon has a coating surface 4a and a layer thickness s1 that is in the range from 0.05 to 1.2 μm. Next to the coating 4, a surface structure 5 is then formed into the coating surface 4a, wherein this structuring was produced by laser interference structuring. Here, closed structure elements 5a, 5b, 5c are formed by the interaction of multiple laser beams, wherein a structure depth s2 of the surface structure 5 is in the range of 0.15 to 0.4 μm. In this respect, the coating 4 is not penetrated by the surface structure 5. With the help of the laser interference structuring, this can also be implemented for smaller layer thicknesses s1. The reference symbol 7 designates a virtual center line 7 of the sliding surface 3.

[0032] By a method according to the invention for producing a sliding surface, surface structures can thus be constructed on a coating of a machine element without the coating being penetrated.

[0033] FIG. 2 shows a three-dimensional view of a machine element 1′ in the form of a rocker arm with two sliding surfaces 3a, 3b. The sliding surfaces 3a, 3b of the machine element 1′ are provided for the sliding use in contact with at least one additional machine element not shown here, wherein the at least one additional machine element slides over the sliding surfaces 3a, 3b in a sliding direction GR. The machine element 1′ is provided in each of two areas of its surface 2 (compare FIG. 1) with a coating 4, 4′ in which a surface structure 5 is then formed by means of laser interference structuring comprising linear structure elements 5a, 5b and point-shaped structure elements 5c.

[0034] Here, viewed perpendicular to a coating surface 4a, 4a′ of the coating 4, 4′, the respective coating surface 4a, 4a′ is divided into two halves parallel to the sliding direction GR by a virtual center line 7a, 7b. The surface structure 5 is formed comprising a number of linear structure elements 5a, 5b that are oriented at an angle Y≠0 relative to the virtual center line 7a, 7b. Here, several of the linear structure elements 5a, 5b form, in paired arrangement, a V-shaped structure 6, wherein a tip of this V-shaped structure 6 is arranged pointing in the sliding direction GR.

[0035] Therefore, the hydrodynamic pressure of an overall liquid lubricant that is deposited on the sliding surfaces 3a, 3b, is, in particular, increased, because the lubricant is pressed out from the two linear structure elements 5a, 5b by a machine element sliding over top in the area of the tip of the V and there generates, in an especially effective way, the hydrodynamic lubricant cushion.

LIST OF REFERENCE NUMBERS

[0036] 1, 1′ Machine element [0037] 2 Surface [0038] 3, 3a, 3b Sliding surface [0039] 4, 4′ Coating [0040] 4a, 4a′ Coating surface [0041] 5 Surface structure [0042] 5a, 5b, 5c Structure element [0043] 5 Structure [0044] 7, 7a, 7b Virtual center line [0045] s.sub.1 Layer thickness [0046] s.sub.2 Structure depth