Hi Prahlad,

Yes your topic is a common one in hot rolling mills and in general steel plants.

There are two varieties:

Continous material like hot rolled coils - computing the weight of these is quite easy : At the unloading platform after being wound and strapped; An on line electronic integrator that uses the thickness inputs ( from the mill mainstand AGC ) and pulse inputs from a rotary encoder down the line; or very simply by a weight indicator attached to the overhead crane hook !( some of these can remotley transmitt the weight to a networked PC also )

Discontinuous material like bars, angles etc . This is a bit convoluted. One option is an in-motion weighing platform that is interposed in the line after the rolling is over;

Other option is a light curtain ( not IR !)with the transmitter and reciever placed on either side of the conveyor. Of course in this method you should get a break between the bars / angle or whatever. Once you get the count data, computing the weight is easy with a user entered value of gm/cm input. I have seen practical implementation of this in a cut-to-length line.

If in case you dont have a break between items, then the only ( cool) option would be to use the velocity information that you already have ( integrate it ) and then compute the weight with the user data input of gm/cm.

HTH

Raghu