Method and device for monitoring the wear condition of a tool

• US 6,732,056 B2
• Filed: 05/15/2001
• Issued: 05/04/2004
• Est. Priority Date: 05/15/2000
• Status: Expired due to Fees

• Current Assignee: Prometec GmbH (Sandvik AB)
• Original Assignee: Prometech GmbH
• Inventors: Reuber, Martin Josef, Kluft, Werner Wilhelm, Kratz, Heinz-Hubert
• Primary Examiner(s): NGHIEM, MICHAEL P
• Application Number:
  US09/854,660
• Publication Number:
  US 20020017139A1
• Time in Patent Office: 1,085 Days
• Field of Search: 702/39, 702/54, 702/59, 702/67, 702/75, 702/34, 702/35, 702/105, 702/182, 702/183, 702/185, 700/175, 700/176, 731/04
• US Class Current: 702/39
• CPC Class Codes: B23Q 17/0971 by measuring mechanical vibrations of parts of the machine arrangements for measuring vibrations B23Q17/12
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 2219/50325 As function of measured vibrations

Abstract

The wear condition of a milling tool is determined by detecting vibrations of the milling tool and a metal workpiece and generating wavelet coefficients which are utilized to evaluate the wear condition of the workpiece. The vibrations are detected at several locations along the metal workpiece or upon a different workpiece under comparable conditions and evaluating workpiece wear on the basis of changes in wear condition parameters at different locations and/or comparable cutting engagement between the milling tool and similar or different workpieces.

Claims

1. A method of monitoring the wear condition of a milling tool (2) during the machining of a metal workpiece (4) comprising the steps of

(a) detecting vibrations of both the milling tool (2) and the metal workpiece (4) at varying cutting, engagement and/or contact conditions between the milling tool (2) and the workpiece (4) at different locations along the workpiece (4),

(b) generating measuring signals from the detected vibrations,

(c) transforming the measuring signals into wavelet coefficients through wavelet functions,

(d) calculating wear condition parameters for the milling tool (2) from the resultant wavelet coefficients,

(e) repeating the performance of steps (a) through (c) at at least another location along one of the metal workpiece (4) or a different workpiece and the milling tool (2) under comparable cutting, engagement and/or contact conditions, and

(f) evaluating the wear condition of the workpiece on the basis of changes in the wear condition parameter of step (d) to that resulting from the performance of step (e).

2. The monitoring method as defined in claim 1 wherein step (a) is performed by detecting vibrations in three-dimensional space along at least one space-defining axis.

3. The monitoring method as defined in claim 1 wherein step (a) is performed by detecting vibrations in three-dimensional space along all three space-defining axes.

4. The monitoring method as defined in claim 3 including performing steps (b) through (d) with respect to the detected vibrations of each of the three space-defining axes incident to performing step (f).

5. The monitoring method as defined in claim 3 including performing steps (b) through (d) with respect to the detected vibrations of each of the three space-defining axes to define three wavelet coefficients, and combining the three wavelet coefficients into a single wavelet coefficient incident to performing step (f).

6. The monitoring method as defined in claim 1 wherein step (a) is performed by detecting vibrations of at least one of (a) the milling tool (2), (b) a milling tool holder, (c) a milling machine milling tool holder support, (d) the workpiece and (e) the machine tool workpiece support.

7. The monitoring method as defined in claim 1 wherein step (a) is performed by utilizing one of an acceleration sensor, a vibration velocity sensor, a vibration path sensor, a solid-borne sound sensor and a sound emission sensor.

8. The monitoring method as defined in claim 1 including the step of monitoring the wear condition of the tool (2) during milling cut interruption.

9. The monitoring method as defined in claim 1 including the step of monitoring the wear condition of the tool (2) during milling tool workpiece cutting.

10. The monitoring method as defined in claim 1 wherein the different locations of step (a) are determined from data of a NC production program of the machine tool.

11. The monitoring method as defined in claim 1 wherein the different locations of step (a) are determined from one of (a) workpiece blank geometry, (b) workpiece finished part geometry, (c) workpiece intermediate cut geometry, (d) machining parameters and (e) tool geometry data of a NC production program of the machine tool.

12. The monitoring method as defined in claim 1 including the step of displaying the wear condition of the milling tool by one of (a) two-dimensional and (b) a three-dimensional representation of a cutting edge of the milling tool.

13. A method of monitoring the wear condition of a milling tool (2) during the machining of a metal workpiece (4) comprising the steps of

(a) detecting vibrations of both the milling tool (2) and the metal workpiece (4) at varying cutting, engagement and/or contact conditions between the milling tool (2) and the workpiece (4) at different locations along the workpiece (4),

(b) generating measuring signals from the detected vibrations,

(c) transforming the measuring signals into wavelet coefficients through wavelet functions,

(d) calculating wear condition parameters for the milling tool (2) from the resultant wavelet coefficients,

(e) repeating the performance of steps (a) through (c) at at least another location along a different workpiece and the milling tool (2) under comparable cutting, engagement and/or contact conditions, and

(f) evaluating the wear condition of the workpiece on the basis of changes in the wear condition parameter of step (d) to one of (a) an initial tool parameter and (b) a parameter at comparable cutting, engagement and/or contact conditions of one of a (a) similar and (b) different workpiece (4).

14. The monitoring method as defined in claim 13 including the step of displaying the wear condition of the milling tool by one of (a) two-dimensional and (b) a three-dimensional representation of a cutting edge of the milling tool.

15. A method of monitoring the wear condition of a milling tool (2) during the machining of a metal workpiece (4) comprising the steps of

(a) detecting vibrations of both the milling tool (2) and the metal workpiece (4) at varying cutting, engagement and/or contact conditions between the milling tool (2) and the workpiece (4) at different locations along the workpiece (4),

(b) generating measuring signals from the detected vibrations,

(c) transforming the measuring signals into wavelet coefficients through wavelet functions,

(d) calculating wear condition parameters for the milling tool (2) from the resultant wavelet coefficients,

(e) repeating the performance of steps (a) through (c) at at least another location along one of the metal workpiece (4) or a different workpiece and the milling tool (2) under comparable cutting, engagement and/or contact conditions, and

(f) evaluating the wear condition of the workpiece on the basis of changes in the wear condition parameter of step (d) at the different locations of step (a) with comparable cutting, engagement and/or contact conditions of one of (a) a similar and (b) different workpiece.

16. The monitoring method as defined in claim 15 wherein step (a) is performed by detecting vibrations in three-dimensional space along at least one space-defining axis.

17. The monitoring method as defined in claim 15 wherein step (a) is performed by detecting vibrations in three-dimensional space along all three space-defining axes.

18. The monitoring method as defined in claim 15 including performing steps (b) through (d) with respect to the detected vibrations of each of the three space-defining axes incident to performing step (f).

19. The monitoring method as defined in claim 15 including performing steps (b) through (d) with respect to the detected vibrations of each of the three space-defining axes to define three wavelet coefficients, and combining the three wavelet coefficients into a single wavelet coefficient incident to performing step (f).

20. The monitoring method as defined in claim 15 wherein step (a) is performed by detecting vibrations of at least one of (a) the milling tool (2), (b) a milling tool holder, (c) a milling machine milling tool holder support, (d) the workpiece and (e) the machine tool workpiece support.

21. The monitoring method as defined in claim 15 wherein step (a) is performed by utilizing one of an acceleration sensor, a vibration velocity sensor, a vibration path sensor, a solid-borne sound sensor and a sound emission sensor.

22. The monitoring method as defined in claim 15 including the step of monitoring the wear condition of the tool (2) during milling cut interruption.

23. The monitoring method as defined in claim 15 including the step of monitoring the wear condition of the tool (2) during milling tool workpiece cutting.

24. The monitoring method as defined in claim 15 wherein the different locations of step (a) are determined from data of a NC production program of the machine tool.

25. The monitoring method as defined in claim 15 wherein the different locations of step (a) are determined from one of (a) workpiece blank geometry, (b) workpiece finished part geometry, (c) workpiece intermediate cut geometry, (d) machining parameters and (e) tool geometry data of a NC production program of the machine tool.

26. The monitoring method as defined in claim 15 including the step of displaying the wear condition of the milling tool by one of (a) two-dimensional and (b) a three-dimensional representation of a cutting edge of the milling tool.