In flat rolling what is a screw down and a top roll balancing mechanism?

Answer 1

In a rolling mill, the screw down (usually electrically operated in big mills) is the mechanism for setting up the spacing between the rollers, called the roll gap. The top roll balancing mechanism is a mechanical (rods, springs) or hydraulic setup to hold the top roller up in contact with the screw down. The larger mills we see in operation have massive rollers, and they have considerable weight. The whole of the upper roll mechanism will be set in heavy chocks to to stabilize it and distribute the loads of the rolling operation. Additionally, we often see mills with backup rollers, and the top work roller and backup roller pair will be held in contact with the screw down by the top roll balancing mechanism. There is a bit more to this when we consider the dynamic operation of the biggest rolling mills, but the basics remain the same. The thickness of the product, the "indexing" of the roll gap, will be set by the screw down. And the the top roller is held up against the screw down by the top roll balancing mechanism.