Ultrasonic tire testing apparatus

• US 4,337,660 A
• Filed: 03/09/1981
• Issued: 07/06/1982
• Est. Priority Date: 08/29/1979
• Status: Expired due to Term

• Current Assignee: Arnold A Weiss
• Original Assignee: AMFM Incorporated
• Inventors: Weiss, Arnold A.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/242,109
• Time in Patent Office: 484 Days
• Field of Search: 73/599, 73/600, 73/626, 73/618
• US Class Current: 73/600
• CPC Class Codes: G01M 17/025 using infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 2291/2692 Tyres
• CPC Class Codes: G01N 29/27 by moving the material relative to a stationary sensor
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/449 Statistical methods not provided for in G01N29/4409, e.g. averaging, smoothing and interpolation

Abstract

An ultrasonic, non-destructive inspection system for detecting separations and/or holes in vehicle tires. The system employs a through transmission method at ultrasonic inspection in which the ultrasonic transmitter array and the ultrasonic receiver array are both mounted in air and in a non-contacting, non-critical relationship with the tire undergoing inspection. The inspection is performed in one revolution of the tire.

The ultrasonic transmitters are pulsed and the receivers are sampled during predetermined time intervals which are related to the transmitter/receiver/tire geometry. This eliminates the problems of talk-around and standing waves. The problem of transmitter--transmitter interference is eliminated by transmitter frequency separation and transmitter array pointing geometry. The problem wherein tread pattern fluctuations in the received signal interfere with flaw detection is eliminated by the use of a finite sampled data filter whose period is adjusted to the period of the tread pattern.

Claims

1. An electronic system for use in ultrasonic inspection apparatus comprising:

(a) a plurality of transmitters for producing directional beams of pulsed ultrasonic energy, the transmitters being physically arranged so that the beams focus on a predetermined area of the product to be inspected;

(b) a plurality of receiving channels, each having

3. The system as in claim 1 wherein said stored program digital computing means controls the pulse repetition rate of said pulsed ultrasonic energy from said plurality of transmitters, the sampling rate of said integrate and hold circuit means and the connection of said plurality of input lines of said multiplexer means to its output line.

5. The apparatus as in claim 3 wherein said digital computing means includes an arithmetic logic unit for performing computations on digital information entered from said storage means in accordance with instructions comprising a stored program, whereby said electrical signals characteristic of said received ultrasonic energy may be classified.

7. Apparatus as in claim 1 wherein said plurality of transmitters comprise:

(a) an array of piezoelectric crystal transducers;

(b) oscillator means coupled to said output means of said digital computing means for receiving triggering pulses at times determined by said digital computing means and producing pulses of a predetermined frequency at an output;

(c) a monostable multivibrator circuit having an input connected to the output of said oscillator means and an output;

(d) power amplifier means connected to the output of said oscillator means and said monostable multivibrator circuit means for producing pulsed bursts of electrical signals of said predetermined frequency; and

(e) means coupling said pulsed bursts of electrical signals from said power amplifier means to said piezoelectric transducers.

8. An electronic system as in claim 1 wherein said digital computing means is coupled to receive said electrical signals characteristic of said received ultrasonic energy and programmed for performing a finite sampled data filter function on said discrete signals, the length of said filter being determined, either adaptively or nonadaptively, by the periodicity of irregularities in said product being inspected.

2. an ultrasonic receiver transducer adapted to receive ultrasonic energy transmitted through said product from at least one of said plurality of transmitters and producing an electrical signal characteristic of said received ultrasonic energy;

2. a bandpass filter coupled to said receiver transducer for attenuating frequency components of said electrical signal above and below a predetermined center frequency;

3. demodulator means coupled to the output of said bandpass filter;

4. an integrate and hold circuit means for periodically integrating the electrical output from said demodulator during a predetermined time interval and holding said integrated, signal;

(c) multiplexer means having a plurality of input lines, an output line and a control line, the output from said integrate and hold circuits of said plurality of receiving channels being coupled individually to said plurality of input lines of said multiplexer means;

(d) an analogue-to-digital converter circuit having its input coupled to said output line of said multiplexer means; and

(e) a stored program digital computing means having input means and output means, said input means being coupled to the output of said analogue-to-digital converter circuit, said output means being coupled to said transmitter means, said integrate and hold circuit means and said control line of said multiplexer means.

4. Apparatus as in claim 2 wherein said digital computing means further includes storage means coupled to said input means and said output means for storing digital signal representations of the sampled values of said electrical output from said demodulator means of each of said plurality of receiving channels.

6. Apparatus as in claim 4 and further including a display device connected to said output means of said digital computing means for providing an indication of the classification into which said electrical signals characteristic of received ultrasonic energy fall.