Dynamical instrument for machining

• US 20040179915A1
• Filed: 03/10/2003
• Published: 09/16/2004
• Est. Priority Date: 03/10/2003
• Status: Active Grant

• Current Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Inventors: Barck, Bruce N., Hill, Wayne S.
• Granted Patent: US 7,341,410 B2
• Time in Patent Office: Days
• US Class Current: 409/131
• 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 19/406 characterised by monitoring or safety G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/37217 Inspect solder joint, machined part, workpiece, welding result
• CPC Class Codes: G05B 2219/37242 Tool signature, compare pattern with detected signal
• CPC Class Codes: G05B 2219/37402 Flatness, roughness of surface
• CPC Class Codes: G05B 2219/37432 Detected by accelerometer, piezo electric
• CPC Class Codes: G05B 2219/37435 Vibration of machine
• CPC Class Codes: Y10T 408/76 Tool-carrier with vibration-damping means
• CPC Class Codes: Y10T 409/101113 Gear chamfering or deburring
• CPC Class Codes: Y10T 409/303752 Process
• CPC Class Codes: Y10T 409/304312 with means to dampen vibration
• CPC Class Codes: Y10T 409/307224 with infeed control means energized in response to activator stimulated by condition sensor
• CPC Class Codes: Y10T 409/30952 with cutter holder
• CPC Class Codes: Y10T 82/2595 with noise or vibration dampener

Abstract

A dynamical instrument for machining comprising a sensor responsive to a non-rotating part of a machine proximate the tool of the machine for outputting a vibration signal, and a processor responsive to the sensor output configured to calculate a plurality of signature quantities which characterize the dynamics of the vibration signal and correlate the signature quantities to detect parameters associated with the operation of the machine.

Claims

1. A dynamical instrument for machining comprising:

a sensor responsive to a non-rotating part of a machine proximate the tool of the machine for outputting a vibration signal; and

a processor responsive to the sensor output and configured to calculate a plurality of signature quantities which characterize the dynamics of the vibration signal and correlate said signature quantities to detect parameters associated with the operation of the machine.

2. The dynamical instrument for machining of claim 1 in which said machine is a lathe.

3. The dynamical instrument for machining of claim 1 in which said machine is a milling machine.

4. The dynamical instrument for machining of claim 1 in which the non-rotating part of the machine is a tool holder.

5. The dynamical instrument for machining of claim 1 in which the non-rotating part of the machine is a spindle assembly.

6. The dynamical instrument for machining of claim 1 in which said tool is a machine bit.

7. The dynamical instrument for machining of claim 1 further including a computer subsystem with a device for outputting the detected parameters associated with the operation of the machine.

8. The dynamical instrument for machining of claim 7 in which the device for outputting the detected parameters includes an electronic console.

9. The dynamical instrument for machining of claim 7 in which the device for outputting the detected parameters includes an auditory device.

10. The dynamical instrument for machining of claim 1 further including a signal conditioner circuit for converting and digitizing the vibration signal output by the sensor to obtain a computer code representation of the sensor time series.

11. The dynamical instrument for machining of claim 1 in which the detected parameters include a measurement of the surface finish of a workpiece as the workpiece is machined.

12. The dynamical instrument for machining of claim 11 in which the measurement of the surface finish of a workpiece includes the average absolute value deviation in the height from a mean line of the surface finish of the workpiece.

13. The dynamical instrument for machining of claim 11 in which the measurement of the surface finish of a workpiece includes the difference in height between the highest peak above a mean line of the surface finish of the workpiece and the lowest valley below the mean line of the workpiece over a sampling length of the workpiece.

14. The dynamical instrument for machining of claim 13 in which the measurement of the surface finish of a workpiece includes the average peak-to-valley height above the mean line of the surface of the workpiece over the sampling length of the workpiece.

15. The dynamical instrument for machining of claim 1 in which the detected parameters include an indication of the status of lubricant flow in the machine.

16. The dynamical instrument for machining of claim 1 in which the detected parameters include an indication if the machine tool is worn or damaged.

17. The dynamical instrument for machining of claim 1 in which the detected parameters include an indication of the remaining life of the machine tool.

18. The dynamical instrument for machining of claim 1 in which the detected parameters include an indication how secure a workpiece is in a clamp of the machine as the workpiece is being machined.

19. The system of claim 8 in which said electronic console outputs a visual display of the detected parameters associated with the operation of the machine.

20. The dynamical instrument for machining of claim 8 in which a said console outputs a visual alarm of the detected parameters associated with the operation of the machine.

21. The dynamical instrument for machining of claim 9 in which said auditory device outputs an auditory alarm of the detected parameters associated with the operation of the machine.

22. The dynamical instrument for machining of claim 1 in which said sensor is an accelerometer.

23. The dynamical instrument for machining of claim 1 in which said sensor is an acoustic sensor.

24. The dynamical instrument for machining of claim 22 in which the sensor includes a charge amplifier for outputting a signal with reduced influence of external noise.

25. The dynamical instrument for machining of claim 23 in which the acoustic sensor includes an amplifier and a narrow band pass filter for outputting a carrier wave with varying amplitude.

26. The dynamical instrument for machining of claim 25 in which calculating the number of signature quantities includes determining variations in the amplitude of the vibration signal.

27. The dynamical instrument for machining of claim 1 in which the processor further includes a neural network trained to correlate said signature quantities to detect parameters associated with the operation of the machine.

28. The dynamic instrument for machining of claim 26 in which a said signature quantity is the average value of the amplitude of the vibration signal.

29. The dynamical instrument for machining of claim 26 in which a said signature quantity is the standard deviation of the amplitude of the vibration signal.

30. The dynamical instrument for machining of claim 26 in which a said signature quantity is the characteristic auto-correlation time of the vibration signal.

31. The dynamical instrument for machining of claim 26 in which a said signature quantity is the average absolute value difference of the amplitude of the vibration signal.

32. The dynamical instrument for machining of claim 26 in which a said signature quantity is the average crossing waves variable of the vibration signal.

33. The dynamical instrument for machining of claim 32 in which a said signature quantity is the root mean square difference of the average crossing waves variable of the vibration signal.

34. The dynamical instrument for machining of claim 32 in which a said signature quantity is the duration of the average crossing waves variable of the vibration signal.

35. The dynamical instrument for machining of claim 32 in which a said signature quantity is the root mean square value of the duration of the average crossing waves variable of the vibration signal.

36. The dynamical instrument for machining of claim 26 in which a said signature quantity is the period of the standard deviation crossing waves of the vibration signal.

37. The dynamical instrument for machining of claim 36 in which a said signature quantity is the duration of crossing waves of the vibration signal.

38. The dynamical instrument for machining of claim 26 in which a said signature quantity is the root mean square duration of standard deviation crossing waves of the vibration signal.

39. The dynamical instrument for machining of claim 26 in which a said signature quantity is both the average value of the amplitude of the envelope and the standard deviation of the average value of the amplitude of the envelope of the vibration signal.

40. A dynamical instrument for machining comprising:

a sensor responsive to a non-rotating part of the machine proximate the tool of the machine for outputting a vibration signal; and

a processor responsive to the sensor output for calculating a number of signature quantities which characterize the dynamics of the vibration signal and correlates said signature quantities to detect parameters associated with the operation of the machine, the processor including an output connected to the machine for varying a machine operating parameters.

41. The dynamical instrument for machining of claim 40 further including a controller connected to the output of the processor and the machine for varying the machine operating parameters.

42. The dynamical instrument for machining of claim 41 in which said controller is connected to a motor of the machine.

43. A dynamical method for machining comprising:

coupling a sensor to a non-rotating part of a machine proximate the tool of the machine for outputting a vibration signal; and

calculating, in response to the vibration signal, a plurality of signature quantities which characterize the dynamics of the vibration signal and correlating said signature quantities to detect parameters associated with the operation of the machine.

44. The method of claim 43 in which the detection of parameters associated with the operation of the machine includes using a neural network trained to calculate the parameters in accordance with the plurality of signature quantities representative of a known parameters associated with the operation of the machine.

45. The method of claim 43 in which calculating the parameters includes determining variations in the amplitude of the amplitude envelope of the vibration signal.

46. The method of claim 45 in which a said signature quantity is the average value of the amplitude of the vibration signal.

47. The method of claim 43 in which a said signature quantity is the standard deviation of the amplitude of the vibration signal.

48. The method of claim 43 in which a said signature quantity is the characteristic auto-correlation time of the vibration signal.

49. The method of claim 43 in which a said signature quantity is the average absolute value difference of the amplitude of the vibration signal.

50. The method of claim 43 in which a said signature quantity is the average crossing waves variable of the vibration signal.

51. The method of claim 43 in which a said signature quantity is the root mean square difference of the average crossing waves variable of the vibration signal.

52. The method of claim 43 in which a said signature quantity is the duration of the average crossing waves variable of the vibration signal.

53. The method of claim 43 in which a said signature quantity is the root mean square value of the duration of average crossing waves variable of the vibration signal.

54. The method of claim 43 in which a said signature quantity is the period of standard deviation crossings of the vibration signal.

55. The method of claim 43 in which a said signature quantity is the root mean square duration of standard deviation crossing waves of the vibration signal.

56. The method of claim 43 in which a said signature quantity is the root mean square duration of standard deviation crossing waves of the vibration signal.

57. The method of claim 43 in which a said signature quantity is both the average value of the amplitude of the envelope and the standard deviation of the average value of the amplitude of the envelope of the vibration signal.

58. The method of claim 43 further including displaying numerical indicators on an electronic console which represent the parameters associated with the operation of the machine.

59. The method of claim 43 further including displaying sounding an audio alarm to indicate if the parameters associated with the operation of the machine are outside a predetermined range.