Oven chain switch

[richm1]

I have a chain in an oven that does not exit the oven that I need to sense the chain links. The oven is 400+F degrees. The atmosphere in the oven is smokey with formeldehyde and oil. I've tried a high temperature inductive switch and fiber optics but neither worked well. Has anyone created a flipper arm or other mechanical device so that a typical inductive or photo proximity switch can be used outside the oven environment - the arm or flipper would actuate when ever a chain link passed it?

 

[IRstuff]

Why do you need to sense the links? Aren't the links driven by a sprocket wheel?

You can attach stuff to the sprocket wheel or there may already be sensors that sense the sprocket wheel rotation.

TTFN

 

[richm1]

The sprockets are out of the question. They are totally embedded in the bed of the oven and can't be seen.

 

[SolderingGunslinger]

The sprockets are out of the question. They are totally embedded in the bed of the oven and can't be seen.

Is the motor which drives the sprocket also imbedded in the floor of the oven? If not, any number of sensor types could be used.

I remain,

The Old Soldering Gunslinger

 

[richm1]

The only problem with the drive is that it's around 50' away from where the chain must be read - this is on a lubrication system that can't be relocated. There is too much chain stretch in 50' to maintain shot-to-point lubrication.

 

[TurboXS]

Can you add an idler sprocket to the chain? If so then the idler sprocket could have holes in it to allow the photo/proximity sensor to work or the shaft could be taken out of the oven and the sensor attached so that it is outside the oven in a lower temperature area.

regards
Pete
(TurboXS)

 

[richm1]

I'm looking for something similar to that. The chain pitch is 6" on one chain and only 3" on the other - it may be too tight of an area for a sprocket. A flipper arm of some sort may work - has anyone used something similar to this to actuate a prox switch?

 

[IRstuff]

The holely sprocket could be interfaced to a fiberoptic cable interface to an external photocell sensor.

TTFN

 

[buzzp]

Seems the inductive or capacitve prox would work. When you tried this how did you set it up? I would think it work good (other than temp and smoke, etc) if you shot it up through the linkage rather than trying to shoot the chain sideways and pick up on the small peaks on the linkage.
Your little device to ride on the links sounds feasible but it is mechanical.

 

[richm1]

The switches that I've tried have been looking down through the linkage and yes, I'm picking up on the chain pins or rolls. The problem with fiber optics is once the face is oily it stops working, the inductive worked semi well but the chain has a 1/2" side to side movement that ended up causing problems. I may have to use a smaller 12mm high temp inductive switch if I can find one in npn.

 

[buzzp]

Well I can see why the problem then with the side to side movement of the chain. What about a magnet on the sprocket detected with a prox switch (capacitive, inductive, or hall-effect)?