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Old July 31st, 2020, 06:41 AM   #16
drforsythe
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I agree with the use of a laser product. I use ultrasonic sensors with good luck, but only on flat surfaces larger than the cone of the sensor (level in liquid tanks). Ultrasonics can be sensitive to reflection, and change in material.
I have used Balluff lasers in the past with good luck. Their website has a good search and filter feature. www.balluff.com. The BOD001W sensor has a range of 200 to 10,000 mm. It has 4-20mA output as well as two NPN/PNP selectable outputs. They have 0-10V available on a different model. This is just one option from one manufacturer.
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Old July 31st, 2020, 05:50 PM   #17
alexbeatle
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The wheel rims have holes, which is why laser signal may shoot through it depending on the orientation and give wrong readings.
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Old July 31st, 2020, 05:51 PM   #18
alexbeatle
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Quote:
Originally Posted by Bit_Bucket_07 View Post
I suspect you're getting false echoes that bounce around inside the wheel prior to being reflected back to the transducer. I've had that problem with enclosed vessels sometimes when using ultrasonics. Seems that laser would be a better choice, but I understand that it would miss the presence of the wheel were it aimed at a hole in the wheel. Perhaps a capacitive distance sensor would work?
I believe capacitive sensors are only for very short distances.
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Old July 31st, 2020, 07:23 PM   #19
drbitboy
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Quote:
Originally Posted by alexbeatle View Post
The wheel rims have holes, which is why laser signal may shoot through it depending on the orientation and give wrong readings.



maybe the holes are affecting the ultrasonic signal as well.


when you say erroneous values, how far out are they? can the bad readings be removed by an algorithm?
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Old August 1st, 2020, 06:52 AM   #20
bara_hence
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As poster before pointed out maybe a software algorithm can do the job.. take x values over y time sort values min to max delete z values in both ends and then use the average of the remaining values..
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Old August 1st, 2020, 10:49 AM   #21
I_Automation
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I worked on stamping presses with coils of steel feeding into them. The steel had to form a loop as the straightener fed at a constant rate (hopefully) and the feeder for the press pulled in the needed amount in one quick pull. The higher the loop got the faster the straightener fed steel. When the loop was at the low limit the straightener stopped.

Other than one off-brand unit (I can't remember the name of) all the ultrasonic sensors to measure the loop, which then controlled the speed of the straightener, were either Waddington or Banner.

If you were near a Waddington sensor and jiggled a keyring the noise would start the straightener moving at a fast speed.

If there was an air leak, or someone with a blow gun, near a Banner sensor that straightener would take off full speed. On that note if an air leak opened during lunch by the time everyone got back the entire coil of steel would have been fed and now a nice pile (that could be 10 to 12 feet tall for thicker steel) would be behind the press, and everybody grab a cutting torch.

For safety I either put BOTH makes together and monitored for a concurrent reading or tied the straightener into the feeder's Feeding signal to the press and if there was no Feeding signal within the past 15 seconds the straightener wouldn't move.

EDIT: For the OP - is anyone around that tire using an air impact, blow gun, another air tool or air chuck? If it is a tire installer then there usually is a ring of air nozzles around the rim opening to blow air into the tire to get it to swell and seat on the rim.

Last edited by I_Automation; August 1st, 2020 at 10:52 AM.
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