Ultrasonic tire testing method and apparatus

• US 5,095,744 A
• Filed: 07/30/1990
• Issued: 03/17/1992
• Est. Priority Date: 04/12/1989
• Status: Expired due to Fees

• Current Assignee: Vulcan Vulcap Industries, Inc.
• Original Assignee: Vulcan Equipment Company Limited
• Inventors: Allan, Dave J., Macecek, Mirek, Bubik, Leslie
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/559,163
• Time in Patent Office: 596 Days
• Field of Search: 73/146, 73/600, 73/618
• US Class Current: 73/146
• CPC Class Codes: G01M 17/025 using infrasonic, sonic or ultrasonic vibrations

Abstract

A method and apparatus for non-destructive ultrasonic testing of tires is disclosed wherein an ultrasonic transmitter is positioned outside of the tire and applies pulses of ultrasound to the tire at a plurality of locations around the tire'"'"'s circumference for transmission through the tire wall and receipt by an ultrasonic receiver located within the tire. The ultrasonic receiver generates signals in response to the received ultrasonic transmissions and a computer processes these signals to generate characterizing data from which defects in the tire may be determined. Signals representative of the defects are then processed to generate a graphic display illustrating the location of the defects with the tire.

Claims

1. A non-destructive method for testing a tire employing pulses of ultrasound transmitted from an ultrasonic transmitter located on one side of a tire wall to an ultrasonic receiver located on the opposite side of the tire wall, the tire wall having an outer surface and an inner surface which when sealed may be pressurized, said method comprising the steps of:

generating characterizing data from the transmission of ultrasound through the tire wall at a plurality of locations around the circumference of the tire by successively applying a series of pulses of ultrasound to the tire wall with the ultrasonic transmitter, sensing the ultrasound emanating from the tire wall with the ultrasonic receiver, and processing a signal produced by the ultrasonic receiver in response to said ultrasonic emanations;

accumulating said characterizing data for said plurality of locations distributed circumferentially around the tire;

determining a repetitive pattern present in the accumulated data; and

identifying defective areas in the tire using the repetitive pattern in searching the accumulated data for such defective areas.

2. The method of claim 1, further including the following steps prior to generating said characterizing data from the transmission of ultrasound through the tire wall:

disposing the ultrasonic transmitter at a pre-established distance from the outer surface of the tire; and

disposing the ultrasonic receiver at a pre-established distance from the inner surface of the tire.

3. The method of claim 2, wherein a plurality of ultrasonic receivers are arranged into an array shaped to conform to a cross-section of the inner surface of the tire wall and wherein the following steps are carried out prior to disposing the ultrasonic receiver at a pre-established distance from the inner surface of the tire wall:

inserting the array of ultrasonic receivers into the tire toward the inner surface of said tire wall; and

rotating the array to dispose the ultrasonic receivers across the tire between sidewalls thereof.

4. The method of claim 1, further including the steps of:

measuring the diameter of the tire; and

determining from the measured diameter the number of locations at which the pulses of ultrasound will be applied.

5. The method of claim 1, further including the steps of:

sealing the inner surface of the tire; and

pressurizing the sealed interior of the tire.

6. The method of claim 5, further including the steps of:

processing signals from the ultrasonic receiver for a plurality of locations over the tire wall to locate air leakage through the tire wall from the pressurized interior of the tire; and

moving the tire to a position for conveniently inspecting a location where said leakage has been identified.

7. The method of claim 1 wherein said characterizing data is generated around at each location around the circumference of the tire by measuring a maximum amplitude of the signal produced by the ultrasonic receiver.

8. The method of claim 7 wherein the amplitude of the signal produced by the ultrasonic receiver is measured during a time interval that continues after the ultrasonic transmitter ceases applying ultrasound to the tire wall.

9. The method of claim 7 wherein the amplitude of the signal produced by the ultrasonic receiver is measured several times per cycle of the ultrasound applied to the tire wall by the ultrasonic transmitter.

10. The method of claim 9 wherein the amplitude of the signal produced by the ultrasonic receiver is measured at least 10 times per cycle.

11. The method of claim 1 wherein the repetitive pattern present in the accumulated data is determined by finding a length for such pattern.

12. The method of claim 11 wherein the length of the repetitive pattern present in the accumulated data is found by:

determining the magnitude of the difference between pairs of characterizing data for a plurality of pairs of locations which are all separated by a first specified distance;

counting the number of such differences whose magnitude exceeds a threshold value;

counting the total number of such differences;

determining a ratio of the number of differences whose magnitude exceeds the threshold value to the total number of differences;

determining if the ratio thus determined is less than other ratios obtained for other specified distances different from the first specified distance; and

assigning as the pattern length the specified distance that has the lowest ratio of the number of differences whose magnitude exceeds the threshold value to the total number of differences.

13. The method of claim 1 wherein the repetitive pattern is used in searching for defective areas by selecting for comparison pairs of the accumulated data that have the same location with respect to the repetitive pattern.

14. The method of claim 1 further comprising the step of presenting a graphic display that depicts locations on the tire at which defects have been identified.

15. In a non-destructive method for testing tires employing pulses of ultrasound transmitted from a plurality of ultrasonic transmitters located on one side of a all of a tire to a plurality of ultrasonic receivers located on the opposite side of the tire'"'"'s wall, the plurality of ultrasonic receivers being arranged into an array shaped to conform to a cross-section of the inner surface of the tire, the wall of the tire having an outer surface upon which the tire may roll and an inner surface which when sealed may be pressurized, an improvement comprising the steps of:

inserting the array of ultrasonic receivers into the tire toward the inner surface thereof;

after the array of ultrasonic receivers is within the tire rotating the array bout an axis to dispose the ultrasonic receivers across the tire between sidewalls thereof; and

disposing the ultrasonic receivers at a pre-established distance from the inner surface of the tire.

16. The method of claim 15 further comprising the steps of:

sealing the inner surface of the tire; and

pressurizing the sealed inner surface of the tire.

17. The method of claim 16 further comprising the steps of:

processing signals from an ultrasonic receiver for a plurality of locations distributed over the wall of the tire to detect ultrasound generated by leakage through the tire'"'"'s wall from the pressurized inner surface thereof; and

moving the tire to position in which it is disposed for conveniently inspecting a location where ultrasound is generated by leakage through the wall of the tire.

18. A nondestructive tire testing apparatus, comprising:

encoder means for producing an electronic signal indicative of rotation of a tire;

a plurality of electronic transmitters for producing ultrasound upon excitation by an electronic signal;

transmitter exciting means responsive to the electronic signal from said encoder means for periodically exciting said ultrasonic transmitters to produce pulses of ultrasound at various locations around a circumference of a tire;

said transmitter exciting means including transmitter selection means for selecting said ultrasonic transmitters for excitation one after another thereby causing said ultrasonic transmitters to produce a series of ultrasound pulses, said series of ultrasound pulses being produced periodically in response to the electronic signal from said encoder means at various locations around a circumference of a tire;

a plurality of ultrasonic receivers equal to said plurality of ultrasonic trasmitters for receiving ultrasound and producing an electronic signal in response thereto, said transmitters and receivers being grouped into pairs, and said ultrasonic receivers being spaced from said ultrasonic transmitters to permit a single wall of a tire to pass there between;

signal processing means for receiving the electrical signal from said ultrasonic receivers, for measuring values of the received electronic signal which characterize the transmission of ultrasound through a wall of a tire, and for storing said measured values;

data processing means for retrieving the measured values stored by said signal processing means, for determining characteristics of the transmission of ultrasound through a wall of a tire from said measured values at a plurality of locations distributed circumferentially about a tire, and for identifying defective locations on a tire from the characteristics of the ultrasound transmitted through a wall of a tire; and

receiver signal multiplexing means, coupling the electronic signal from said ultrasonic receivers to said signal processing means and operating in synchronism with said transmitter selection means, for selectively coupling to said signal processing means the electronic signal from that ultrasonic receiver which is paired with the ultrasonic transmitter selected for excitation by said transmitter selection means.

19. A nondestructive tire testing apparatus, comprising:

encoder means for producing an electronic signal indicative of rotation of a tire;

a plurality of electronic transmitters for producing ultrasound upon excitation by an electronic signal;

transmitter exciting means responsive to the electronic signal from said encoder means for periodically exciting said ultrasonic transmitters to produce pulses of ultrasound at various locations around a circumference of a tire;

said transmitter exciting means including transmitter selection means for selecting said ultrasonic transmitters for excitation one after another thereby causing said ultrasonic transmitters to produce a series of ultrasound pulses, said series of ultrasound pulses being produced periodically in response to the electronic signal from said encoder means at various locations around a circumference of a tire;

a plurality of ultrasonic receivers for receiving ultrasound and producing an electronic signal in response thereto, said ultrasonic receivers being arranged into an array shaped to conform to a cross-section of an inner surface of a tire and spaced from said ultrasonic transmitters to permit a single wall of a tire to pass there between;

receiver positioning means for retracting said array of ultrasonic receivers out of a tire during tire removal or installation and for inserting said array of ultrasonic receivers into a tire toward the inner surface thereof during tire testing, said receiver positioning means rotating said array of ultrasonic receivers about an axis after said array is within a tire to dispose said ultrasonic receivers across such tire between sidewalls thereof;

signal processing means for receiving the electrical signal from said ultrasonic receivers, for measuring values of the received electronic signal which characterize the transmission of ultrasound through a wall of a tire, and for storing said measured values; and

data processing means for retrieving the measured values stored by said signal processing means, for determining characteristics of the transmission of ultrasound through a wall of a tire from said measured values at a plurality of locations distributed circumferentially about a tire, and for identifying defective locations on a tire from the characteristics of the ultrasound transmitted through a wall of a tire.

20. A nondestructive tire testing apparatus, comprising:

encoder means for producing an electronic signal indicative of rotation of a tire;

an ultrasonic transmitter for producing ultrasound upon excitation by an electronic signal;

transmitter exciting means responsive to the electronic signal from said encoder means for periodically exciting said ultrasonic transmitter to produce pulses of ultrasound at various locations around a circumference of a tire;

an ultrasonic receiver for receiving ultrasound and producing an electronic signal in response thereto, said ultrasonic receiver being spaced from said ultrasonic transmitter to permit a single wall of a tire to pass there between;

signal processing means for receiving the electrical signal from said ultrasonic receiver, for measuring values of the received electronic signal which characterize the transmission of ultrasound through a wall of a tire, and for storing said measured values;

data processing means for retrieving the measured values stored by said signal processing means, for determining characteristics of the transmission of ultrasound through a wall of a tire from said measured values at a plurality of locations distributed circumferentially about a tire, and for identifying defective locations on a tire from the characteristics of the ultrasound transmitted through a wall of a tire;

tire sensing means for contacting an outer surface of a tire to measure a diameter thereof; and

pulse location control means operative in conjunction with said transmitter exciting means to establish the locations around a circumference of a tire at which said ultrasonic transmitter will be excited.

21. A nondestructive tire testing apparatus comprising:

encoder means for producing an electronic signal indicative of rotation of a tire;

an ultrasonic transmitter for producing ultrasound upon excitation by an electronic signal;

transmitter exciting means responsive to the electronic signal from said encoder means for periodically exciting said ultrasonic transmitter to produce pulses of ultrasound at various locations around a circumference of a tire;

an ultrasonic receiver for receiving ultrasound and producing an electronic signal in response thereto, said ultrasonic receiver being spaced from said ultrasonic transmitter to permit a single wall of a tire to pass there between;

signal processing means for receiving the electrical signal from said ultrasonic receiver, for measuring values of the received electronic signal which characterize the transmission of ultrasound through a wall of a tire, and for storing said measured values;

data processing means for retrieving the measured values stored by said signal processing means, for determining characteristics of the transmission of ultrasound through a wall of a tire from said measured values at a plurality of locations distributed circumferentially about a tire, and for identifying defective locations on a tire from the characteristics of the ultrasound transmitted through a wall of a tire; and

tire mounting means adapted to seal a tire so it may be pressurized, said tire mounting means including a hub on each side of a tire together with rings which may be of various different outer diameters to adapt said tire mounting means for use with various different sizes of tires, one such ring being respectively juxtaposed about each of said hubs and sealed therewith to prevent leakage between said hub and said ring when a tire is pressurized.

22. A nondestructive tire testing apparatus, comprising:

encoder means for producing an electronic signal indicative of rotation of a tire;

an ultrasonic transmitter for producing ultrasound upon excitation by an electronic signal;

transmitter exciting means responsive to the electronic signal from said encoder means for periodically exciting said ultrasonic transmitter to produce pulses of ultrasound at various locations around a circumference of a tire;

an ultrasonic receiver for receiving ultrasound and producing an electronic signal in response thereto, said ultrasonic receiver being spaced from said ultrasonic transmitter to permit a single wall of a tire to pass there between;

signal processing means for receiving the electrical signal form said ultrasonic receiver, for measuring values of the received electronic signal which characterize the transmission of ultrasound through a wall of a tire during a time interval that continues after the ultrasonic transmitter ceases applying ultrasound to the wall of a tire, and for storing said measured values; and

data processing means for retrieving the measured values stored by said signal processing means, for determining characteristics of the transmission of ultrasound through a wall of a tire from said measured values at a plurality of locations distributed circumferentially about a tire, and for identifying defective locations on a tire form the characteristics of the ultrasound transmitted through a wall of a tire.