RESONANCE TIRE INSPECTION METHOD AND APPARATUS

• US 3,815,407 A
• Filed: 01/22/1973
• Issued: 06/11/1974
• Est. Priority Date: 01/22/1973
• Status: Expired due to Term

• Current Assignee: Adelbert L. Lavery
• Original Assignee: Adelbert L. Lavery
• Inventors: Lavery, Adelbert L.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US05/325,392
• Time in Patent Office: 505 Days
• Field of Search: 73/67,67.2,67.5,146
• US Class Current: 73/582
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01M 17/025 using infrasonic, sonic or ultrasonic vibrations

Abstract

The non-destructive testing of tires to determine the presence of structural defects is accomplished by measuring imbalance in the transmission characteristics of a tire from the tread area to a pair of oppositely disposed points on the side walls as a test tire is rotated and contacted on the tread area by a vibrator which is caused to track a resonant frequency of the tire. Variations in resonant frequency as well as variations in transmission characteristics which do not unbalance the symmetry of the tire are also measured and the information collected permits identification of both the presence and nature of hidden defects.

Claims

1. A method for the non-destructive testing of tire casings comprising the steps of:

rotating the casing about its axis;

causing the casing to vibrate at a resonant frequency thereof during rotation;

varying the frequency of the vibrations imparted to the exterior of the casing in the tread region to compensate for changes in resonant frequency caused by physical variations in the casing; and

simultaneously detecting lack of symmetry in the transmission characteristics in the region of the casing by a pair of receiver transducers positioned on opposite casing sidewalls in the same radial cross-section of the casing at which the vibrations are imparted to the casing.

2. The method of claim 1 wherein the step of causing the casing to vibrate comprises:

applying a vibrating source transducer to the casing tread area by roller means positioned such that the vibrating force remains in contact with the casing as the casing is rotated circumferentially.

3. The method of claim 1 wherein the step of detecting symmetry imbalance comprises:

applying a pair of receiver transducers respectively to the opposite side walls of the casing at points equally spaced from the point of application of the source transducer.

4. The method of claim 1 further comprising the step of:

measuring the frequency and changes thereof at which the casing is vibrating as the casing is rotated circumferentially.

5. The method of claim 4 further comprising the step of:

continuously measuring the output frequency of the source transducer as the frequency of operation thereof is varied to maintain resonance.

6. The method of claim 5 wherein the step of detecting symmetry imbalance further comprises:

comparing the output signals generated by the receiver transducers.

7. The method of claim 6 further comprising the step of:

comparing the output of one of the receiver transducers with the results of the comparison of the outputs of both receiver transducers.

8. Apparatus for use in the non-destructive testing of tires comprising:

vibratory source transducer means for application to the tread area of a tire casing to be tested;

means for causing said source transducer means to track a resonant frequency of the test tire;

first receiver transducer means for application to a first side wall of thE test tire, said first receiver transducer means generating an output signal commensurate with the magnitude of vibrations transmitted thereto through the tire casing from said source transducer means;

second receiver transducer means for application to the second side wall of the test tire at a position oppositely disposed to said first receiver transducer means, said second receiver transducer means generating an output signal commensurate with the magnitude of vibrations transmitted thereto through the tire casing from said source transducer means, said first and second receiver transducer means and said source transducer means being intended for positioning in a plane defined by a tire cross-section; and

means for comparing the output signals generated by said receiver transducer means to provide an indication of a transmission symmetry imbalance.

9. The apparatus of claim 8 further comprising:

means for measuring the source transducer means operating frequency and for providing an output signal commensurate therewith.

10. The apparatus of claim 9 wherein said means for comparing the receiver transducer means output signals comprises:

comparator means responsive to the transducer output signals for providing an output signal commensurate with variations therebetween indicative of symmetry imbalances; and

means responsive to a symmetry imbalance signal for providing an indication thereof.

11. The apparatus of claim 10 wherein the output of said frequency measuring means is applied to said indication providing means for display and wherein said apparatus further comprises:

means delivering the output of one of said receiver transducers to said indication providing means for display.