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Ultrasonic crack detection in glass bottles

  1. Mar 10, 2015 #1
    I'm working on a project for a bottling plant that is trying to make a vision-based machine to detect cracked glass bottles before they attempt to fill them.

    It seems that the vision & backlight approach is the standard way to do this in the industry, but the shape of the bottle in this application makes this a tricky/expensive machine.

    I'm wondering if anyone has any experience with some type of ultrasonic crack detection methodology? I'm just going on a hunch here, but I think that at least some cracks should change the resonate frequency of a bottle enough to detect the change..
     
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  3. Mar 10, 2015 #2

    NascentOxygen

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    Staff: Mentor

    Can you provide a pic of the bottle's shape?
     
  4. Mar 11, 2015 #3

    Bystander

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    Shows a lot of flaws --- laser plus beam expander (cylindrical lens in front of laser level light source) and a diode array looking for reflections, or reduced transmission.
     
  5. Mar 11, 2015 #4

    Baluncore

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    Support a bottle by one point, say by the cap, then tap the bottle so it rings like a bell at a fundamental frequency. If there is a fracture in a bottle it will sound dull and generate a short burst of harmonics of the fundamental frequency. I expect the harmonics generated to be even because the crack opens for part of the cycle but is closed on the other half cycle. With a good bottle the ringing will continue for longer at the fundamental frequency and there will be less 2'nd harmonic generated.
     
  6. Mar 11, 2015 #5
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