URUGUAY JOBS GIS

3. Stay within ideal operating parameters of the machine.

It is recommended that manufactures identify what material and what thickness represent their highest volume of work. Then (a company) can deliver a machine that will camber to that specification, thus conserving valuable production hours and eliminating large amounts of scrap.

1. Quality rolling machines are usually cambered at 50 percent of the full-rated value of the machine. Hence, a 1-inch machine is cambered to roll 1/2-inch plate at a nearly perfect edge.
2. Disregarding this important fact can result in out-of-spec product that the customer will not accept. Problems most commonly arise when rollers attempt to push the upper limits of their plate roll. If 5/8-inch plate is rolled through a 1-inch-rated machine, a small degree of barrel effect will likely occur. This may or may not be an acceptable margin for error. However, when plate thickness approaches the upper end of a machine's rating, then severe defects can occur. Unless corrected with a shim, it will not be sellable. Conversely, when very thin material is rolled through a machine rated for very thick plate, the finished product may come out tighter in the center than at the ends. Again, time consuming shimming is necessitated to correct for this "hourglass" effect.

4. Carefully consider bending diameters. The tighter the diameter, the more bend pressure required. For instances where thick material must be rolled into tight inside diameters (ID), the diameter of the top roll and the layout of the machine can make the difference between a product whose cylindrical edges meet and one that won't close.

As a rule of thumb, most machines can roll plate at 1 1/2 times the upper roll diameter. Hence, given a 10-inch-diameter top roll, inside diameters as tight as 15 inches can be obtained. However, new machines that incorporate planetary guides are able to keep approximately 50 percent more area of the plate under bend-pressure during the rolling operation, thereby achieving ratios of 1.1 times the upper roll diameter. This creates a 30 percent advantage on tight diameters.

All machines achieve precise measurements at 50 percent of the full-rated value. Therefore, given a 1.1 roll geometry, a 3/8-inch machine with a 10-inch top roller can consistently roll 3/16-inch plate to 11-inch ID without any barrel defect.