Rotary encoder

I am having a problem with losing the rotary encoder on a flying shear at our plant. Mainly due to shock and vibration, I was wondering what brands or types of encoders you guys might be using for a high shock application?

My favorite position sensor for high shock environments is the HT-20 resolver from AMCI. You can beat on them with a ball peen hammer and they won't break.

The resolver signal must be decoded by a remote device. We used them with PLC5 cards and with SLC cards also made by AMCI. These were also very reliable. It is also an absolute position signal, so homing was not required.

If you need a quadrature encoder signal, check out their duracoder line which is based on resolver technology with onboard ruggedized decoding.

Paul

Make sure you get an encoder that has high resolution. My customers have used several brands that seem to work just find. Danaher, BEI, Stegmann come to mind.

Now think about this. If the encoder that in monitoring the line speed is subject to that much shock, what do you think that is doing to the encoder readings. The output of the encoder must be accurate and smooth since it is what the rest of the system is geared to. The motion controller should have some way of monitoring and graphing the lines speed and the speed should not have noise on it.

Another issue is that the shear does not match the line speed. This can cause the encoder to stall or pull which then affects the shear speed. The problem amplifies itself.

The same effect can be seen to a lesser degree caused by the shear pushing the metal down while shearing. When the metal is pushed down it pulls on the up and down stream material. This in turn affects the encoder rotation and the speed of the shear.

The point is that you must make sure the mechanical part are right.

The encoder is mounted on the blade shaft that is engaged with a clutch/brake mechanism. The TIR on the stub shaft for the encoder is .002. I am using avtron m685 encoders right now and ranging from about 3-7 days before the pickup is rubbing the wheel and causing loss(double/triple cuts, swing with no cut, lost home). The line speed is 250 - 300 fpm. The blade rpm goes from 0-1400-0 in about 1.8 seconds.

Something I have looked at but not yet had a chance to play with are high resolution non contact magnetic encoders. Typically have a look here.
http://www.phoenixamerica.com/products/encoders/default.html

Bryan