METHOD FOR PROCESSING A SURFACE OF A METAL OBJECT SUCH AS A METAL SYNCHRONIZING RING FOR MANUAL TRANSMISSIONS

Abstract

A method includes providing a metal ring and pastelessly slide-grinding at least one surface of the metal ring with grinding bodies, preferably until a predefined surface topography of the metal ring is achieved, which surface topography preferably has an Rsk value that is greater than or equal to 0.25 and/or an Rk value between 0.3 and 1.35 and/or Rpk value between 0.05 and 0.4 and/or an Rvk value between 0.2 and 1.2 and/or an Ra value between 0.1 and 0.4.

Claims

1. A method comprising: providing a metal ring; and pastelessly slide-grinding at least one surface of the metal ring with grinding bodies.

2. The method according to claim 1, wherein the slide-grinding is carried out until a predefined surface topography of the at least one surface of the metal ring is achieved.

3. The method according to claim 2, wherein the predefined surface topography has an Rsk value that is greater than or equal to 0.25.

4. The method according to claim 3, wherein the predefined surface topography has an Rk value between 0.3 and 1.35, an Rpk value between 0.05 and 0.4, an Rvk value between 0.2 and 1.2, and/or an Ra value between 0.1 and 0.4.

5. The method according to claim 4, wherein the slide-grinding is carried out over a period of 0.8 to 1.2 hours.

6. The method according to claim 4, including rinsing the metal ring after the slide grinding.

7. The method according to claim 1, wherein the slide-grinding directly immediately follows a mechanical processing of the metal ring.

8. The method according to claim 5, wherein the metal object is comprised of hardened steel.

9. The method according to claim 4, wherein the slide-grinding comprises placing the metal ring in a container with grinding chips and moving the container to cause a relative movement between the metal ring and the grinding bodies.

10. A steel ring formed according to the method of claim 4.

11. A manual transmission comprising: the steel ring according to claim 9 as a synchronizing ring; and a brass ring mounted adjacent to the synchronizing ring and configured to contact the steel ring.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0020] FIG. 1 is a flowchart showing sequence of a method for processing the surface of a metal object according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0021] In the following, identical or functionally equivalent elements are designated by the same reference numbers.

[0022] FIG. 1 shows a method for processing the surface of a metal object such as a synchronizing ring of a manual transmission. The method includes a first step 101 of a raw processing of a metal object. In this step the metal object receives its coarse shape, for example, as a metal ring. The metal object can be comprised in particular of steel, for example, hardened steel. With use in transmissions, metal rings made of steel, for example, can be used in combination with brass rings. Since brass is softer than steel, a contact between the steel rings and the brass rings leads to wear of the brass rings.

[0023] In order to keep the wear low of the adjacent brass surface, the metal ring is subjected to a slide-grinding in a step 102 directly after a previous mechanical processing, such as, for example, reshaping, hard turning, or grinding, without a previous honing step.

[0024] Here the surface of the metal ring is slide ground. In order to achieve a surface topography that is optimized for an adhesion of lubricant and simultaneously has no peaks that would be initially ground down in use (i.e., would lead to wear of the adjacent surface), the slide-grinding is carried out as pasteless slide-grinding with grinding bodies. This means that the grinding paste is omitted. The peaks of the surface of the metal ring are thereby specifically smoothed; sufficient scoring is simultaneously maintained in the surface structure so that lubricant can adhere. In this way friction values can be optimized in comparison to previous methods over the entire service life in particular with contact of the surface with an uncoated brass surface. Due to such controlled friction values the wear of the contacting brass surface is also reduced.

[0025] The grinding bodies used in slide-grinding can have any desired shapes and can be configured, for example, round, square, or pyramid-shaped. The grinding bodies can be comprised of a ceramic material.

[0026] The pasteless slide-grinding of step 102 is carried out until a predefined surface topography is achieved. For this purpose experience values can be used over the required duration of the slide-grinding. Alternatively the surface topography can be monitored during the slide-grinding, and the process can be stopped as soon as the defined values are achieved. In particular only the peaks of the surface profile are flattened here, however the metal ring is not slide-ground until a completely smooth surface is achieved. In particular the surface topography can have a Rsk value that is greater or equal to 0.25.

[0027] Step 102 can be carried out over a period of 0.8 to 1.2 hours and can include both the grinding itself and a rinsing of the grinding bodies from the metal object. For example, the grinding can be carried out over a period of 0.8 hours, and the subsequent rinsing can be carried out over a period of 0.2 hours.

[0028] In summary a method is provided for processing a surface of a metal object, in particular of a metal ring. Here the processing of the surface is effected by pasteless slide-grinding, whereby a surface structure is obtained, using which an optimized contact of the processed surface with, for example, uncoated brass surfaces, and thus an improved function with simultaneously minimized wear of the surfaces can be achieved in comparison to previous methods.

[0029] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved processing of metal rings.

[0030] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0031] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

[0032] 101 Method step [0033] 102 Method step