Leveling, AutoFlat Shape Correction & Flatness Level

AutoFlat Automatic Shape Correction

AutoFlat is a patented leveler control system that takes automation to the next level. The system reads the shape of the strip as it leaves the leveler and by closed loop control automatically adjusts roll bending to achieve and maintain flat strip. The system works on the fly and provides a dynamic readout of strip shape.

AutoFlat will seek the correct flight positions automatically, and dynamically controls work roll bending even when the incoming strip changes shape.

The AutoFlat system relieves the operator from adjusting the roll bending on the leveler. Results are consistent flat strip regardless of operator expertise and training.

To correct shape and configure a leveler we need to know the physical properties of the material. These properties are thickness, width, yield strength, and the modulus of elasticity.

Yield strength is how much stress or force it takes to permanently deform the material. In other words the point at which after stretching or deforming the material it will no longer spring back to its original dimension. This number is normally stated in units of PSI or a metric equivalent.

Shape defects

Virtually all shape defects are cause by non uniform dimensions and most can be corrected.
When flat metal strip is really flat all the dimensions of the strip are equal. This means that thickness is uniform; the length of the strip is uniform from edge to edge and in line with the strip. If any of these dimensions are not uniform the strip tends to have bad shape. An easy way to understand this is consider a short length of tube; obviously the OD is larger than the ID. If you would cut open the tube and try to bend it flat it will spring back to it’s curved form because of non uniform dimensions.

	COIL SET Top side is longer than the bottom side in line with the length of the strip.
	CROSS BOW Top or bottom side is longer than the other side, Length differential can be in line with the strip or from edge to edge.
	EDGE WAVE Edges are longer than the center across the width and in line with the strip.
	CENTER BUCKLE Center is longer than the edges across the width and in line with the strip.
	CAMBER From edge to edge the strip gradually gets longer, basically a large arc Can be improved but very difficult to impossible to completely correct with a leveler
	CROWN Thickness is greater in the center than the edges cannot be corrected with a leveler
	INTERNAL STRESS Strip appears flat but apposing internal deformities are present but cancel each other out until released. Internal stress is a shape defect usually in the form of coil set, edge wave, or center buckle that is not apparent until the material is cut or processed later.