Sensor - Bran /wheat bread factory

Ramil · Jul 9, 2003

I am working for a bread manufacturing plant.
We face one problem. I need a sensor to solve this problem.

Our dows are carried in small buckets like conveyor and some time this bucket contains two or more dows. We need to make sure that only one Dow is present at all time in the bucket.
Now suppose two dows are present in one bucket and if that enters oven without our notice . then we have a big problem to remove it as it is backed and becomes big sized.

We put an ordinary diffuse type photo sensor. But the problem is that it some time detects the bucket itself.(i mean the bucket edge). So if i adjust the sensivity then it does not detect the second dow.
our dow (Bran bread mostly - so white brown color) and some time wheat bread (white color).

Can you please suggest some idea on which sensor would be suitable for this kind of applicaiton

Thanking you all

seppoalanen · Jul 9, 2003

Sounds trainable 'form-detector' f.e. Omron ?

RoTaTech · Jul 9, 2003

a capacitive sensor would detect the dough.
You may need a second sensor, or your current photoeye, to trigger it when to look, so it does not see the edges of your bucket.
Have you tried triggering your current sensor, to only look as the dough is passing it, rather than all the time the bucket is passing? That should work, as you said you can adjust the sensitivity and make it work sometimes.

mrdegold · Jul 9, 2003

I would try to find a spot on the conveyer area where the loaded bucket would pass over a scale and be weighed. At which point you could compare the weight of the loaded bucket with a known weight and if it is not within an acceptable tolerance reject the bucket for inspection.
Then all you would need to do when you change products is adjust the compared weight to the known weight of the new product.
hope this helps

Jim Dungar · Jul 9, 2003

Color sensing

If your dough and bucket are two different colors (colours, for our non-US friends), you can use a "full color detector" photo sensor.

http://www.squared.com/us/products/sensors.nsf/DocumentsByCategory/2D2AD6684A37205C852567080051951F

Tom Jenkins · Jul 9, 2003

Really wierd idea

Have the bucket move past an air hose. Use a prox to detect the bucket and turn on the air with a solenoid valve. Use another prox switch to detect how far the bucket swings. A double filled bucket should not swing as far as a single filled bucket.

SLaubach · Jul 9, 2003

Cognex or DVT make cameras realtivly cheap that can pick that up without issue.

panic mode · Jul 9, 2003

just a tought

If you use photoeye now, maybe all you need is to get
better photoeye for example one with background suppression.

Vetteboy · Jul 9, 2003

Cheapest method yet........

Since the edge of a bucket is so small, have a tiny time delay that will ignore it, looking for a second dow a fraction of a second after it's first blocked. If you are using bit shifting look for a group of bits larger than a bucket edge.

Goody · Jul 9, 2003

And another of a thousand suggestions - can you place the sensor above and over the bucket so that it only see's double filled ones

Ramil · Jul 10, 2003

Many thanks

Many thanks for all your suggestions.
Here are some more details about our line.

6 buckets are chained together. none of them could be seperated.
The distance or gap between each bucket is 15mm.
Bucket is around 120mm high. dough hieght will be approx 60mm.
If two doughs are present it will exactly cover one bucket hieght.

Right now we have placed the diffused photo sensor above the bucket. Around 150 mm above dough (assuming only one dough).

Bucket material is steel. (color of bucket = aluminium color)
Dough color - white brown and little dark white brown.

Thanking you all

ed · Jul 10, 2003

Ramil:
Hang two sensors above the buckets, sensors should be spaced at half the diameter of the bucket. Wire them in series, adjust sensitivity to trigger when height is higher than one dough. If both trigger at same time there are two doughs in bucket. If only one triggers (bucket edge) nothing happens.

Eric Nelson · Jul 10, 2003

Normally, I'd be all for the 'non-contact' approach (photoelectric, capacitive, laser, ultrasonics, camera, etc., etc.), but in THIS case, why NOT just use a simple limit switch?...

Mounted over the bucket, the actuator can hang like a pendulum. The bucket edge will actuate the limit switch, but as the bucket passes, the actuator will swing down into the bucket. At this point, you check the limit switch. If it remains actuated, there is extra dough present.

A simple (albeit crappy) drawing might help clarify what the heck I'm talking about...
[attachment]
Actually, this WOULD qualify as a non-contact sensor, since during normal operation, the limit switch never contacts the dough!...

That is, if I understood the applicaton correctly...

beerchug

-Eric

Ramil · Jul 10, 2003

Thanks again

Thanking you all for your suggestion.

I now have so many suggestion. All are equally good. I should be successfull with one of the above .

I donot know how to thank you all for spending your valuable time.

I realy liked that drawing by Eric.Thanks Eric. I even thought of putting a rough drawing of our line.
If possible i will take a snap of our line and would put it here.

SLaubach · Jul 10, 2003

Eric wins! Good idea, sometime we tend to put too much thought into simple problems....

Sensor - Bran /wheat bread factory

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