Steel plate rollers (whether there are two or three bottom rollers) have a top roller. The size of the top roller can be adjusted to roll the board into a cylinder or cylinder segment so that its radius is close to the diameter of the top roller. However, the relatively small top roller will deflect in the center under the pressure of the bent steel plate. Alternatively, larger diameter upper rolls have less deflection, but limit the machine to rolling only larger diameter rolls.
Bending machines and rollers, equipment specially used to bend steel plates in other steel products, are required to roll steel plates of various widths, lengths and thicknesses. Some possibilities will cause the top roll to deform during the rolling process. The result will be a plate cylinder with a cylindrical shape with non-parallel ends.
For plate rollers with longer top rollers and smaller diameters, you will see greater deflection. Imagine standing between 6 x 4 wooden beams supported at both ends. As the length of the wooden beam becomes longer, the deflection of your standing position will further decrease. The same concept also applies to steel plate rolling.
To compensate for this deflection of the plate roller, the top roller is "crowned". "Top crown" refers to the barrel shape of the top roller, which is required to obtain an even distribution of the pressure required for steel plate rolling. Both ends of the plate roller are supported. When the plate moves, the top roller is offset in the middle. This will affect the parallelism of the rolled part edges.
A Crown on the Top Roll of a Steel Plate Roll
Convexity on top roll of steel plate rollThe crowning process can be achieved by grinding or cutting on a large, modern CNC lathe. The program will use the deflection formula or list value to generate the correct shape to balance the contraction pressure.
It is recommended to crown the top roller of the material used in most cases. For example, if you always run a ½ inch thick, 3 foot wide steel plate to make a 30 inch diameter cylinder, you can make the top rolled convex surface meet these specifications. However, if you pass a 2 inch thick board through the machine with the same width to the same radius, you will see a barrel-shaped final product. If you roll a 1 / 8-inch thick plate with the crowned top roller over the same roll, you will see an hourglass-shaped final product.
Bending machines and rollers not only run plates of uniform thickness, width and diameter, so they cannot crown their top rollers to full size. Thick plate rolling companies usually use many different thick plate rolls to increase the thickness, width and diameter of thick plates.
If you need to use the wrong convexity plate roller to roll the plate, you can use the shim to artificially increase the thickness to correct the convexity. The most common gasket is cardboard, but you can also use metal and wood gaskets. To correct the barrel effect, the machine operator can place a shim in the center of the board. To correct the hourglass effect, the machine operator can place the shims on each corner of the top of the board while rolling.
Then, according to your requirements, you should consider convex processing of the plate roller to produce high-quality steel cylinders and cylinder blocks.
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