Limit Switch Dilemma

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Thread Starter

Tim A. Herman

We specified proximity switches for a conveyor line that will transport ton-containers in an environment that will have water and caustic
washdown at 3000 psig and 194 F (NEMA 4X). The problem is that the sensing distance is now found to be too small due to irregularities in
the dimensions of the containers, and we need to find some other method of detecting the container as it moves down the line. We are trying
to stay away from mechanical means, and the environmental conditions are such that optics would not be suitable. Any suggestions would be
welcome. Thank you.
 
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Ted Boerding

Assuming you're using roller conveyor, you might try putting a deprssable roller in the path of the container. This would look much like an
accumulator roller on a conveyor unit. When the container depresses the roller, a flag on the roller assembly could pass in front of the prox. switch to give you a signal that will always be within range of the sensing area.

Another way to mount the prox switch would be to thread it into a piece of 1" steel welded to the frane of the conveyor such that when the roller comes down on the steel block, the prox sitch would be protexcted from impact with the face of the roller tab.

I hope this rather inadequate desciption helps.

Good luck,
 
T

Ted Boerding

Assuming you're using roller conveyor, you might try putting a deprssable roller in the path of the container. This would look much like an
accumulator roller on a conveyor unit. When the container depresses the roller, a flag on the roller assembly could pass in front of the
prox. switch to give you a signal that will always be within range of the sensing area.

Another way to mount the prox switch would be to thread it into a piece of 1" steel welded to the frane of the conveyor such that when the roller comes down on the steel block, the prox sitch would be protexcted from impact with the face of the roller tab.

I hope this rather inadequate desciption helps.

Good luck,
 
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Gabriele Corrieri

A simple suggestion, have you try with a SONAR switches? Look at Siemens Bero Sonar,there is a various model from a simple switch to analog version. We have used this version for maintain the distance between two mobile trolley: one have mounted the Bero, the other had one surface face to sensor. We have get an PID loop on this sensor for moving the two trolley at same distance between them. The sensor (diameter 18mm) sensing distance from
20 cm up to 1 meter.
 
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