I need to make a special measuring timer

etpm · 2013-04-21T20:34:33+00:00

Greetings All, I have a customer that I make an assembly for that he uses in another assembly to stake parts. By staking parts I mean dents are put in the first part to retain a second part that fits in a hole in the first part. Anyway, two dents are put in the part and they need to be done simultaneously to prevent shifting of the parts. The parts I make work perfectly but when the customer assembles everything the staking process sometimes doesn't work because the punches that do the staking don't hit the parts at the same time and they need to be adjusted. The punches first contact the parst, holding them in place with spring pressure, then the punches are struck by a spring loaded hammer that is actuated by a cam. So, after this long description what needs to be done is the timing of the punches being struck needs to be measured. I'm thinking of maybe using a piezo disc under each punch and then cycling the machine and looking for a voltage spike with both channels of a 'scope. I'm not sure how much voltage the disc would generate though and if it would damage the 'scope. I have a TEK 465B oscilloscope but I'm not sure it would be best suited for this job. I can buy a cheap 4 channel DSO that I think would work, see this link: I think it would measure the timing of the voltage spikes to a fine enough interval for what the customer needs. I think the timing of the strikes can be measured to within at least 1 millisecond which would be plenty fine enough. Then the machines can be adjusted. Any thoughts anyone? Thanks, Eric

Apr 21, 2013 22 Replies

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etpm 13 years ago

Greetings Bob, I like the mike idea too. Thanks. I need to see if I can use two and separate the sound coming from the punches. I may be able to bond the mikes to the punches or something that the punches hit. Thanks also for the offer of help with your software. Eric

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Bob Masta 13 years ago

Again, try this first with a single equidistant microphone before you consider the hassles of using two. If you see two distinct peaks you not only know it's going to work, but you can probably do the whole job with that one mic.

If you only see one peak, or it's too messy to tell, it may still be worth watching what happens as you tweak the hammer timing... if the single peak becomes stronger, you can assume you are moving toward coincident hits. When it becomes broader or breaks up into separate peaks, you are going the wrong way.

Best regards,

Bob Masta DAQARTA v7.21 Data AcQuisition And Real-Time Analysis

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Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, Pitch Track, Pitch-to-MIDI FREE Signal Generator, DaqMusic generator Science with your sound card!

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etpm 13 years ago

Thanks Bob, I'll try the single mic first. Eric

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