Acoustic detection of cracks in metal pieces
First Claim
1. A device for detecting a crack in a metal piece comprising:
- anvil means;
means for producing an impact between the metal piece and the anvil means, said impact generating an acoustic wave formed of a plurality of components, one of said components being produced by vibrations of said metal piece and having a frequency indicating a cracked or uncracked state of the metal piece;
means for sensing and measuring the energy of said one component of said generated acoustic wave within a predetermined time gate and within a predetermined frequency bandwidth; and
means for determining if said metal piece is cracked or uncracked in accordance with said measured energy;
said anvil means being designed so that its vibrations generated by the impact produce no acoustic wave component at a frequency located within said predetermined frequency bandwidth in order to prevent influence on said energy measurement of any component of said generated acoustic wave produced by the anvil means.
2 Assignments
0 Petitions
Accused Products
Abstract
An acoustic crack detection method and device in which an impact is produced between an actually tested metal piece and an anvil. This impact generates an acoustic wave formed of a plurality of components, one of these wave components being produced by vibrations of the metal piece and having a frequency indicating a cracked or uncracked state of this piece. A microphone senses the acoustic wave generated by the impact and a measuring circuit receives the signal from the microphone for measuring the energy, within a predetermined time gate and within a predetermined frequency bandwidth, of the wave component of interest. The measured energy is compared with a reference level in order to determine if the actually tested metal piece is cracked or not. Of course, the anvil is designed so that its vibrations produced by the impact generate no wave component at a frequency included within the predetermined frequency bandwidth, whereby the crack detection is not disturbed by any acoustic wave component generated by the anvil. The detecting device may be used in an apparatus for sorting cracked and uncracked metal pieces.
10 Citations
24 Claims
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1. A device for detecting a crack in a metal piece comprising:
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anvil means; means for producing an impact between the metal piece and the anvil means, said impact generating an acoustic wave formed of a plurality of components, one of said components being produced by vibrations of said metal piece and having a frequency indicating a cracked or uncracked state of the metal piece; means for sensing and measuring the energy of said one component of said generated acoustic wave within a predetermined time gate and within a predetermined frequency bandwidth; and means for determining if said metal piece is cracked or uncracked in accordance with said measured energy; said anvil means being designed so that its vibrations generated by the impact produce no acoustic wave component at a frequency located within said predetermined frequency bandwidth in order to prevent influence on said energy measurement of any component of said generated acoustic wave produced by the anvil means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for detecting a crack in a metal piece comprising the steps of:
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producing an impact between the metal piece and anvil means, said impact generating an acoustic wave formed of a plurality of components, one of said components being produced by vibrations of said metal piece and having a frequency indicating a cracked or uncracked state of the metal piece; sensing and measuring the energy of said one component of said generated acoustic wave within a predetermined time gate and within a predetermined frequency bandwidth, and determining if said metal piece is cracked or uncracked in accordance with said measured energy; said anvil means being designed so that its vibrations generated by the impact produce no acoustic wave component at a frequency located within said predetermined frequency bandwidth in order to prevent influence on said energy measurement of any component of said generated acoustic wave produced by the anvil means. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification