optical range finder

[easypilot]

Our production line is destroying hall effect sensors. They are temporarily mounted on an axle to sense a steel wheel position as it is pressed on to the axle. When in range, the two wire switching sensor simply halts the hydraulic press cycle. The close proximity of this sensor to the wheel, its wiring, and mounting are proving cumbersome and time consuming for the operator to install and remove.

I would like to reposition an image sensor to the press anvil about ten feet away and be able to program 4 different ranges. The sensor must have an accuracy +/- .020 inches and a response time of >100 mSec. Although the wheels are rusty, the area reflecting the light source could be sanded clean or could accept a temporary magnetic reflector target if necessary. Working within the constraints of an off the shelf product would obviously be my first choice. Does anyone know where I might find one with a fast response and a ten foot range?

 

[nbucska]

Can you give more detail? <nbucska@pcperipherals.com>

 

[easypilot]

nbucska --

Thank you for your response.

We place a large steel axle on rests built onto the bed of our 200 ton horizontal hydraulic press.

I am currently using a 2 wire hall effect sensor affixed to the thimble of an inside micrometer. A long steel rod, precisely cut to our required wheel to wheel distance is affixed to the micrometer's anvil. This assembly is attached to a v-block which is then velcro strapped to the axle by the press operator. After the axle shaft ends are prep'd with anti-galling lubricants, a large steel wheel whose inside diameter will provide an interference fit to the axle is placed in the press. The operator will check the overall length of the sensor assembly with a standard, adjust the micrometer thimble to correct any out of tolerance limits, and start the press cycle. When the sensor assembly detects wheel presence, it energizes a stop circuit which halts the press cycle.

This process has worked quite well over the years except when the operator accidently drops the sensor assembly, or negligently tangles the 2 wire cord in the press structure breaking the plug or cord strain relief, which in turn shorts out fuses in the hydraulic control circuitry.

If I can eliminate the delicate handling requirement of the sensor, by permanently mounting an optical range sensor on the press structure, then I can eliminate downtime due to sensor damage.

It is not economically feasible to modify the press so the wheel could merely break a light beam. I need to accurately measure distance between the sensor and the reflecting surface of the wheel. We press 4 different dimensions. I would therefore like to program 4 different ranges to trigger the stop circuitry.

I hope this will clarify your understanding and provide enough detail. Can you direct me to a supplier of optical range sensors?

 

[nbucska]

Could you send me a sketch ? <nbucska@pcperipherals.com>