TOOL AND METHOD FOR MECHANICAL SURFACE TREATMENT

Abstract

A tool for mechanical surface treatment includes a housing, a roller body, and a resonator. The housing has a cavity for filling with a hydraulic medium having a basic pressure. The roller body is for rolling on a workpiece surface to be treated and is exposed to the basic pressure of the hydraulic medium. The resonator is arranged for generating targeted pressure pulses in the hydraulic medium. In some example embodiments, the housing has a tubular body with a tip and the roller body is arranged at the tip. In an example embodiment, the roller body is a sphere. In an example embodiment, the tool includes a seal for sealing the roller body to the tubular body.

Claims

1.-10. (canceled)

11. A tool for mechanical surface treatment comprising: a housing comprising a cavity for filling with a hydraulic medium with a basic pressure; a roller body for rolling on a workpiece surface to be treated, the roller body being exposed to the basic pressure of the hydraulic medium; and a resonator arranged for generating targeted pressure pulses in the hydraulic medium.

12. The tool of claim 11, wherein: the housing comprises a tubular body with a tip; and the roller body is arranged at the tip.

13. The tool of claim 12, wherein the roller body is a sphere.

14. The tool of claim 12, further comprising a seal for sealing the roller body to the tubular body.

15. The tool of claim 11, wherein the resonator is built into the housing.

16. The tool of claim 11, wherein the resonator is part of a piezoelectric actuator.

17. A method for mechanical surface treatment, comprising: providing a rotating metallic workpiece with a surface; providing the tool of claim 11 for treating the surface with a pulsating pressure; providing the hydraulic medium with the basic pressure to the tool; and superimposing pressure pulses of the hydraulic medium on the basic pressure to apply the pulsating pressure in a targeted manner.

18. The method of claim 17, further comprising rotating the rotating metallic workpiece at a rotational speed, wherein a frequency of the pulsating pressure is at least 24 times the rotational speed.

19. The method of claim 18, further comprising linearly displacing the tool relative to the rotating metallic workpiece at a linear displacement speed, wherein the linear displacement speed differs from a surface speed of the roller body on the rotating metallic workpiece by at least a factor of 6.

20. The method of claim 17 wherein the rotating metallic workpiece is a roller bearing ring or sliding bearing ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In the following, an exemplary embodiment of the disclosure is explained in more detail by means of two drawings. In the figures:

[0032] FIG. 1 shows a tool for mechanical surface machining in a simplified sectional illustration, and

[0033] FIG. 2 shows an illustration of roller burnishing with pulsating pressure in the rolling contact.

DETAILED DESCRIPTION

[0034] A tool 1 for mechanical surface machining has a housing 2 which, in the exemplary embodiment, is designed as a tubular body. The tool 1 is intended for modified roller burnishing and, for the sake of simplicity, is also referred to as a roller burnishing tool. The tool 1 is used to machine a surface of a workpiece that is intended to function as a sealing surface. For example, it can be a sealing surface of a bearing, e.g., a roller or plain bearing, e.g., a wheel bearing. The sealing surface is formed directly on a bearing ring of the bearing, e.g., a roller bearing ring of a wheel bearing.

[0035] As can be seen from FIG. 1, a resonator 4 is integrated into the housing 2 of the tool 1. The resonator 4 is part of a piezoelectric actuator 3 and adjoins a cavity 5 which extends through the tubular body and is filled with a hydraulic medium. The hydraulic medium is, for example, a hydraulic oil or a cooling lubricant.

[0036] The cavity 5 runs through the entire tubular body, with two portions 7, 8 of narrowed cross section adjoining a central portion 6 with an enlarged cross section. An end portion 9 of the cavity 5 at the tip of the tubular body is widened in relation to the portion 7 and extends as far as a machining ball, which is generally referred to as the roller body 10.

[0037] The machining ball protrudes from the tubular body and is sealed off therefrom by a seal 11. On the opposite side, i.e., the rear side, of the tubular body, an additional seal 12 can be seen, allowing for the sealed connection of the tool 1 to a pressure medium supply.

[0038] A basic pressure p.sub.0 of the hydraulic medium is set in the cavity 5 by the pressure medium supply. A pulsating application of pressure is superimposed on this basic pressure p.sub.0 by the piezoelectric actuator 3, including the resonator 4. The individual pressure pulses or pressure impulses Δ.sub.p ensure that the roller body 10 generates individual depressions in a metallic workpiece surface during the machining process.

[0039] During the machining process, in one embodiment of the disclosure, the workpiece is clamped into a machining device, e.g., a lathe. The workpiece surface to be machined typically has a cylindrical shape. The tool 1 is brought up to the workpiece in the radial direction for machining and is displaced in the axial direction during the machining, i.e., in the longitudinal direction of the workpiece central axis. The frequency at which the machining ball pulsates is many times higher than the surface speed of the workpiece. The contact between the roller body 10 and the workpiece surface is permanently maintained during the machining process.

[0040] FIG. 2 shows an illustration of roller burnishing with a pulsating pressure profile in the area of the rolling contact between the roller body 10 and a metallic workpiece.

[0041] The diagram shows the rolling pressure p plotted against the rolling path l.sub.w covered on the surface of the workpiece. The pressure profile of the roller body 10 on the surface of a workpiece to be roller burnished is shown. Starting from the basic pressure p.sub.0 required for roller burnishing, positive pressure pulses or pressure impulses Δ.sub.p are generated, and a maximum pressure p.sub.0+Δp is achieved, which is transmitted to the workpiece to be machined in a pulsating manner. This results in a permanent surface structure on the metallic workpiece with depressions which, in the area of a sealing surface of such a workpiece for example, has the advantages described above with regard to wear resistance, friction of the seal, and the sealing effect achieved.

[0042] The pulsating pressure profile does not necessarily have to describe a sinusoidal curve, as shown approximately in FIG. 2, but can also show rising, decreasing, repeating, different and also irregular profiles of the maximum pressure distributed over the surface of the workpiece in the course of the rolling path l.sub.w.

REFERENCE NUMERALS

[0043] 1 Tool [0044] 2 Housing [0045] 3 Piezoelectric actuator [0046] 4 Resonator [0047] 5 Cavity [0048] 6 Middle portion [0049] 7 Portion [0050] 8 Portion [0051] 9 End portion [0052] 10 Roller body [0053] 11 Seal [0054] 12 Additional seal [0055] l.sub.w Rolling path [0056] p.sub.0 Basic pressure during roller burnishing [0057] Δp Pressure pulse [0058] T.sub.m Number or pressure pulses per distance unit