Method for machining materials by milling and subsequent brushing

Patent metadata

Field	Value
Publication number	US-9919404-B2
Application number	US-201314415589-A
Country	US
Kind code	B2
Filing date	Jul 15, 2013
Priority date	Jul 27, 2012
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

A method for machining a material, in particular steel, is provided. The material is milled at such a high cutting speed that residual tensile stresses close the surface that exceed a specified value can occur and the residual tensile stresses can be lowered below the specified value by subsequent brushing. A device for performing the method is also provided.

First claim

The invention claimed is:

1. A method for machining a material, comprising:
milling at a high cutting rate such that internal tensile stresses close to a surface which exceed a predetermined value may arise,
subsequent brushing to reduce the internal tensile stresses which exceed the predetermined value so as to be below the predetermined value, and
employing a brushing device in which brushes are present, such that brushing with the brushing device may be simultaneously carried out at a plurality of points.

2. The method as claimed in claim 1 ,
wherein grooves are milled into turbine shafts or into wheel disks.

3. The method as claimed in claim 1 ,
wherein brushing converts the internal tensile stresses into internal compressive stresses.

4. The method as claimed in claim 1 ,
wherein brushing is achieved by a translational and/or rotational movement.

5. The method as claimed in claim 1 ,
wherein the brushes are disposed on the brushing device such that a plurality of regions of a groove may be simultaneously brushed.

6. The method as claimed in claim 1 ,
wherein the brushes and bristles fastened thereon are optimized with respect to a desired reduction of the internal tensile stresses and to a desired service life of the brushing device,
wherein it is considered in the optimization that a reduction of the internal tensile stresses depends on a material of the bristles, a relative position of the bristles, a stiffness of the bristles, a speed of the bristles, a population density, and on internal tensile stresses which are present at a commencement of brushing.

7. The method as claimed in claim 1 ,
wherein the brushes comprise bristles that comprise one of the following: stainless steel, steel, nonferrous metals, plastic, plastic comprising embedded abrasive means, and natural bristles.

8. The method as claimed in claim 1 ,
wherein the brushes comprise bristles that comprise stainless-steel wire, a bristle diameter of 0.15 mm to 0.35 mm, and a tensile strength of 1500 N/mm 2 to 2400 N/mm 2 .

9. The method as claimed in claim 8 ,
wherein the bristles comprise a ratio of bristle length to bristle diameter of 30 to 500.

10. The method as claimed in claim 1 ,
wherein the milling takes place using high-speed steel cutting materials or carbide cutting materials.

11. The method as claimed in claim 1 ,
wherein the milling takes place at a milling feed rate of up to 38 mm/min.

12. A brushing device configured for carrying out a method according to claim 1 .

13. The brushing device as claimed in claim 12 ,
wherein the brushes comprise a contour adapted to grooves to be milled.

14. The method as claimed in claim 1 ,
wherein the material comprises steel.

15. The method as claimed in claim 2 ,
wherein the grooves comprise fir-tree grooves.

16. The method as claimed in claim 8 ,
wherein the tensile strength is 1800 N/mm 2 to 2100 N/mm 2 .

17. The method as claimed in claim 11 ,
wherein the milling feed rate is up to 13 mm/min.

18. A method for machining a material, comprising:
milling at a high cutting rate such that internal tensile stresses close to a surface which exceed a predetermined value may arise, and
subsequent brushing to reduce the internal tensile stresses which exceed the predetermined value to below the predetermined value,
wherein brushes comprising bristles comprising stainless-steel wire are employed, which bristles comprise a bristle diameter of 0.15 mm to 0.35 mm and a tensile strength of 1500 N/mm 2 to 2400 N/mm 2 .

19. A method for machining a material, comprising:
milling at a high cutting rate such that internal tensile stresses close to a surface which exceed a predetermined value may arise, and
subsequent brushing to reduce the internal tensile stresses which exceed the predetermined value to below the predetermined value,
wherein the milling takes place at a milling feed rate of up to 38 mm/min.

Assignees

• Siemens Ag

Inventors

• David Walter
• Knoche Wolfram

Classifications

• B23P9/00 Primary

  Treating or finishing surfaces mechanically, with or without calibrating, primarily to resist wear or impact, e.g. smoothing or roughening turbine blades or bearings (treatment covered by a single other subclass, see the relevant subclass, e.g. B24C, C21D7/00, C22F1/00); Features of such surfaces not otherwise provided for, their treatment being unspecified · CPC title

• Y10T409/303808

  including infeeding · CPC title

• B23P9/02

  Treating or finishing by applying pressure, e.g. knurling (B23P9/04 takes precedence) · CPC title

• B24B39/00 Primary

  Burnishing machines or devices, i.e. requiring pressure members for compacting the surface zone (modifying the physical properties or structure of metal by burnishing C21D7/08, C22F1/00); Accessories therefor · CPC title

• B23C2220/28

  Finishing · CPC title