Thread forming fasteners for ultrasonic load measurement and control

• US 20060130590A1
• Filed: 01/31/2006
• Published: 06/22/2006
• Est. Priority Date: 01/29/2001
• Status: Active Grant

• Current Assignee: Innovation Plus, LLC
• Original Assignee: Innovation Plus, LLC
• Inventors: Kibblewhite, Ian E., Molsbergen, Robert
• Granted Patent: US 7,467,556 B2
• Time in Patent Office: Days
• US Class Current: 73/761
• CPC Class Codes: F16B 2031/022 using an ultrasonic transducer
• CPC Class Codes: F16B 25/10 Screws performing an additional function to thread-forming, e.g. drill screws or self-piercing screws
• CPC Class Codes: F16B 31/02 for indicating the attainment of a particular tensile load or limiting tensile load apparatus for, or method of, determining value of torque or twisting moment for tightening a nut or other member similarly stressed G01L5/24
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

An ultrasonic load measurement transducer is mated with a thread-forming fastener to provide a load indicating thread-forming fastener that can be used for the precise and reliable assembly of critical bolted joints, such as those in the automobile and aerospace industries, among others. Steps can then be taken to accurately measure and control the load in the thread-forming fastener during tightening, and to inspect the load in the thread-forming fastener after assembly. A similar result can be achieved for a thread-locking fastener by mating an ultrasonic transducer with the thread-locking fastener assembly.

Claims

1. An apparatus comprising:

a thread-forming fastener including a head for engagement by a tool for applying a torque to the fastener, and a body portion extending from the head and including thread-forming portions; and

an ultrasonic transducer coupled with the fastener, for making ultrasonic load measurements in the fastener.

2. The apparatus of claim 1 wherein the ultrasonic transducer is coupled with the head of the fastener.

3. The apparatus of claim 1 wherein the ultrasonic transducer is permanently attached to the fastener.

4. The apparatus of claim 3 wherein the ultrasonic transducer is comprised of a piezoelectric polymer film permanently attached to the head of the fastener.

5. The apparatus of claim 3 wherein the ultrasonic transducer is comprised of an oriented piezoelectric thin film, vapor deposited directly on the head of the fastener.

6. The apparatus of claim 1 wherein the ultrasonic transducer is temporarily attached to the fastener.

7. The apparatus of claim 1 which further includes an identifying element applied to the apparatus, wherein the identifying element includes data associated with the fastener.

8. The apparatus of claim 7 wherein the identifying element is a permanent mark applied to the apparatus.

9. The apparatus of claim 8 wherein the permanent mark is a bar code.

10. The apparatus of claim 9 wherein the bar code is applied to the ultrasonic transducer.

11. The apparatus of claim 9 wherein the bar code is applied to the fastener, and the ultrasonic transducer is applied over the bar code.

12. The apparatus of claim 11 wherein the ultrasonic transducer is formed of a translucent material.

13. The apparatus of claim 8 wherein the permanent mark is an indentation formed in a surface of the fastener.

14. The apparatus of claim 8 wherein the permanent mark is applied to an end surface of the fastener.

15. The apparatus of claim 7 wherein the identifying element is a non-volatile memory device applied to the ultrasonic transducer.

16. The apparatus of claim 15 wherein the non-volatile memory device has a top surface and a bottom surface, and an exposed conductive layer on portions of the top surface which is electrically connected to a conductive layer on the bottom surface, and wherein the conductive layer on the bottom surface is in close proximity to an active element of the ultrasonic transducer so that the bottom conductive layer functions as an electrode.

17. The apparatus of claim 16 wherein the conductive layer on the top surface is electrically connected to the non-volatile memory device, for writing information to and for reading information from the memory device.

18. The apparatus of claim 15 wherein the non-volatile memory device is a radio frequency identification device.

19. The apparatus of claim 18 wherein the portions of the conductive layer on the top surface and the conductive layer on the bottom surface function as an antenna for communicating with a transponder associated with the radio frequency identification device.

20. The apparatus of claim 18 wherein the radio frequency identification device has an antenna, and wherein the antenna provides a non-contact coupling with the ultrasonic transducer for performing ultrasonic load measurements.

21. The apparatus of claim 18 wherein the ultrasonic transducer and the radio frequency identification device each operate at a defined frequency, and wherein the frequency for the ultrasonic transducer is the same as the frequency for the radio frequency identification device.

22. A method of making a load indicating, thread-forming fastener, comprising the steps of:

providing a fastener having a first end including a surface for receiving an ultrasonic transducer, for making ultrasonic load measurements in the fastener, a shank extending from the first end and including thread-forming portions for tapping a hole, and a second end, opposite the first end and including a surface for reflecting an ultrasonic wave back to the first end; and

attaching an ultrasonic transducer to the first end of the fastener.

23. The method of claim 22 which further includes the step of attaching the ultrasonic transducer to a head associated with the first end of the thread-forming fastener, for engagement by a tool for applying a torque to the fastener.

24. The method of claim 22 which further includes the step of permanently attaching the ultrasonic transducer to the fastener.

25. The method of claim 24 which further includes the step of permanently attaching an ultrasonic transducer comprised of a piezoelectric polymer film to the first end of the fastener.

26. The method of claim 24 which further includes the step of vapor depositing an ultrasonic transducer comprised of an oriented piezoelectric thin film directly onto the first end of the fastener.

27. The method of claim 22 which further includes the step of temporarily attaching the ultrasonic transducer to the fastener.

28. The method of claim 22 which further includes the step of applying an identifying element to the fastener, wherein the identifying element includes data associated with the fastener.

29. The method of claim 28 which further includes the step of applying a permanent mark to the fastener.

30. The method of claim 29 which further includes the step of applying a bar code to the fastener.

31. The method of claim 30 which further includes the step of applying the bar code to the ultrasonic transducer.

32. The method of claim 30 which further includes the steps of applying the bar code directly to the fastener, and applying the ultrasonic transducer over the bar code.

33. The method of claim 28 which further includes the step of forming an indentation in a surface of the fastener.

34. The method of claim 28 which further includes the step of applying the identifying element to an end surface of the fastener.

35. The method of claim 28 which further includes the step of applying a non-volatile memory device to the ultrasonic transducer.

36. The method of claim 35 which further includes the steps of providing an exposed conductive layer on portions of a top surface of the non-volatile memory device, and electrically connecting the exposed conductive layer to a conductive layer on a bottom surface of the non-volatile memory device, placing the conductive layer on the bottom surface in close proximity to an active element of the ultrasonic transducer so that the bottom conductive layer functions as an electrode.

37. The method of claim 36 which further includes the step of electrically connecting the conductive layer on the top surface to the non-volatile memory device, for communicating with the memory device.

38. The method of claim 35 which further includes the step of applying a radio frequency identification device to the ultrasonic transducer.

39. A method of measuring a load in a fastener, comprising the steps of:

providing a thread-forming fastener including a head for engagement by a tool for applying a torque to the fastener, and a body portion extending from the head and including thread-forming portions;

coupling an ultrasonic transducer with the fastener, for making ultrasonic load measurements in the fastener;

electrically connecting an apparatus to the ultrasonic transducer for supplying signals to the ultrasonic transducer and for receiving signals from the ultrasonic transducer;

monitoring the signals received from the ultrasonic transducer, providing an accurate measurement indicative of the load in the fastener; and

adjusting the measurement indicative of the load to compensate for effects of heating of the fastener resulting from forming a thread in a mating component during installation.

40. The method of claim 39 which further includes the step of imparting torque to the fastener and removing torque from the fastener in response to the measurement of the load in the fastener.

41. The method of claim 39 which further includes the step of determining a zero-load ultrasonic measurement, using the measurement indicative of the load in the fastener.

42. The method of claim 41 which further includes the step of measuring a torque in conjunction with the measurement indicative of the load in the fastener to determine the zero-load ultrasonic measurement.

43. The method of claim 41 which further includes the step of measuring an angle of rotation of the fastener in conjunction with the measurement indicative of the load in the fastener to determine the zero-load ultrasonic measurement.

44. The method of claim 41 which further includes the step of measuring time in conjunction with the measurement indicative of the load in the fastener to determine the zero-load ultrasonic measurement.

45. The method of claim 41 which further includes the step of taking measurements for determining the zero-load ultrasonic measurement prior to a load-inducing stage of the installation.

46. The method of claim 41 which further includes the step of taking measurements for determining the zero-load ultrasonic measurement during a load-inducing stage of the installation.

47. The method of claim 39 which further includes the step of placing an identifying element on the fastener which contains data associated with the fastener.

48. The method of claim 47 wherein the identifying element is a permanent mark applied to the ultrasonic transducer, and wherein the method further includes the step of directly reading the permanent mark applied to the ultrasonic transducer.

49. The method of claim 47 wherein the identifying element is a permanent mark applied to the fastener, wherein the ultrasonic transducer is applied over the permanent mark, and wherein the method further includes the step of reading the permanent mark applied to the fastener through the ultrasonic transducer.

50. The method of claim 47 wherein the identifying element is a non-volatile memory device applied to the ultrasonic transducer, and wherein the method further includes the step of directly reading the non-volatile memory device applied to the ultrasonic transducer.

51. A method of measuring a load in a fastener, comprising the steps of:

providing a thread-locking fastener assembly including a bolt having a head for engagement by a tool for applying a torque to the fastener assembly and a body portion extending from the head, and a nut for cooperating with the body portion of the bolt, wherein portions of the fastener assembly include resistance-inducing threads;

coupling an ultrasonic transducer with the bolt, for making ultrasonic load measurements in the fastener assembly;

electrically connecting an apparatus to the ultrasonic transducer for supplying signals to the ultrasonic transducer and for receiving signals from the ultrasonic transducer;

monitoring the signals received from the ultrasonic transducer, providing an accurate measurement indicative of the load in the fastener assembly; and

adjusting the measurement indicative of the load to compensate for effects of heating of the fastener assembly resulting from prevailing torque associated with the thread-locking fastener assembly.

52. The method of claim 51 which further includes the step of imparting torque to the bolt and removing torque from the bolt in response to the measurement of the load in the fastener assembly.

53. The method of claim 51 which further includes the step of determining a zero-load ultrasonic measurement, using the measurement indicative of the load in the fastener assembly.

54. The method of claim 53 which further includes the step of measuring a torque in conjunction with the measurement indicative of the load in the fastener assembly to determine the zero-load ultrasonic measurement.

55. The method of claim 53 which further includes the step of measuring an angle of rotation of the fastener in conjunction with the measurement indicative of the load in the fastener assembly to determine the zero-load ultrasonic measurement.

56. The method of claim 53 which further includes the step of measuring time in conjunction with the measurement indicative of the load in the fastener assembly to determine the zero-load ultrasonic measurement.

57. The method of claim 53 which further includes the step of taking measurements for determining the zero-load ultrasonic measurement prior to inducing the load in the fastener assembly.

58. The method of claim 53 which further includes the step of taking measurements for determining the zero-load ultrasonic measurement while inducing the load in the fastener assembly.

59. The method of claim 51 which further includes the step of placing an identifying element on the fastener assembly which contains data associated with the fastener assembly.

60. The method of claim 59 wherein the identifying element is a permanent mark applied to the ultrasonic transducer, and wherein the method further includes the step of directly reading the permanent mark applied to the ultrasonic transducer.

61. The method of claim 59 wherein the identifying element is a permanent mark applied to the fastener assembly, wherein the ultrasonic transducer is applied over the permanent mark, and wherein the method further includes the step of reading the permanent mark applied to the fastener assembly through the ultrasonic transducer.

62. The method of claim 59 wherein the identifying element is a non-volatile memory device applied to the ultrasonic transducer, and wherein the method further includes the step of directly reading the non-volatile memory device applied to the ultrasonic transducer.