| Unfortunately, many buyers end up purchasing | | | | 70, Hardox 400/500 series and AR 200/300 |
| equipment that lacks the capability and | | | | series, for example. And these different |
| flexibility to meet production volumes and | | | | steels require varying pressures to roll.3. |
| tolerances, simply because they don't | | | | Carefully consider bending diametersAll |
| understand all available options and | | | | machines achieve precise measurements at 50 |
| considerations.Between diminishing factory | | | | percent of the full-rated value. Therefore, |
| orders and increasing labor and energy costs, | | | | given a 1.1 roll geometry, a 3/8-inch machine |
| companies that use plate metal in their | | | | with a 10-inch top roller can consistently |
| fabricating processes are finding their | | | | roll 3/16-inch plate to 11-inch ID without |
| profit margins increasingly pinched.Yet, | | | | any barrel defect.As a rule of thumb, most |
| manufacturers must still invest in new | | | | machines can roll plate at 1 1/2 times the |
| production equipment -- whether to replace | | | | upper roll diameter. Hence, given a |
| obsolete equipment or to take advantage of | | | | 10-inch-diameter top roll, inside diameters |
| new business opportunities -- in order to | | | | as tight as 15 inches can be obtained. |
| remain competitive.Manufacturers must make | | | | However, new machines that incorporate |
| careful assessments when evaluating the | | | | planetary guides are able to keep |
| addition of new plate-rolling equipment. Debt | | | | approximately 50 percent more area of the |
| capital is still available to purchase new | | | | plate under bend-pressure during the rolling |
| machinery, but paying back the loan will not | | | | operation, thereby achieving ratios of 1.1 |
| yield a satisfactory return on investment | | | | times the upper roll diameter. This creates a |
| unless the equipment adds value to the | | | | 30 percent advantage on tight diameters.The |
| production.In an effort to help manufacturers | | | | tighter the diameter, the more bend pressure |
| optimize plate rolling operations, 5 key | | | | required. For instances where thick material |
| considerations are offered in order to choose | | | | must be rolled into tight inside diameters |
| a proper plate bending machine.1. Work with | | | | (ID), the diameter of the top roll and the |
| an equipment dealer that is willing to | | | | layout of the machine can make the difference |
| discuss your specific plate-rolling | | | | between a product whose cylindrical edges |
| needsCustomers must know the correct | | | | meet and one that won't close.4. Incorporate |
| questions to ask, in order to get the correct | | | | both side and vertical supports to prevent |
| answers. Each manufacturer faces unique | | | | unwanted bendsWhen rolling a cylinder, once |
| challenges, and through systematic querying | | | | the inside diameter is more than 200 times |
| an astute sales representative can determine | | | | greater than the thickness of the material, |
| exactly what equipment will work best for | | | | the weight of the material becomes sufficient |
| their process.Customers need to discuss | | | | to bend the cylinder as it exits the top roll |
| issues such as inside diameters, material | | | | and gets further away from the machine. |
| type, tolerances and the desired shape of the | | | | Without proper support, unwanted radii |
| finished product. As an example, some | | | | result.Purchasing a machine with both side |
| products, such as those found in the pressure | | | | and vertical roller supports easily solves |
| vessel industry, demand a maximum of 1 | | | | this problem.Some manufacturers attempt to |
| percent out-of-round on their diameters or | | | | skimp on this ancillary equipment by |
| they are considered defective. By using an | | | | resorting to "makeshift" support such as a |
| underpowered plate roller, too much of a | | | | forklift or overhead crane. However, this |
| barrel effect can render such a product | | | | shortcut ties up the use of equipment that |
| useless and quickly erase any potential | | | | can best be utilized elsewhere. Because it |
| profit margin.Manufacturers must also | | | | cannot adequately support the material, |
| carefully consider whether they wish to roll | | | | unforeseen bends can still appear.Adequate |
| conical or parabolic shapes to take advantage | | | | support requires both side and vertical |
| of a broader market. Hydraulically operated | | | | roller-supports, as designed by the |
| four-roll machines are ideal for this type of | | | | manufacturer of the plate-rolling machine. |
| work by eliminating surface scarring, thereby | | | | Once employed, plate rolling becomes a |
| decreasing the need for grinding the | | | | one-man job instead of two. This frees up |
| lamination (bullnosing) on the minor diameter | | | | valuable manpower that can be re-routed to |
| edge of a cone.Accurate conical rolling is | | | | other jobs.5. Stay within ideal operating |
| further achieved through features such as | | | | parameters of the machineIt is recommended |
| torsion bar parallelism, as opposed to | | | | that manufactures identify what material and |
| electronic systems or proportional value | | | | what thickness represent their highest volume |
| systems that merely maintain a theoretical | | | | of work. Then (a company) can deliver a |
| balance. Finite parallelism allows the | | | | machine that will camber to that |
| machine to be adjusted to its full conical | | | | specification, thus conserving valuable |
| tilt and back to parallel in only five | | | | production hours and eliminating large |
| seconds.Matching plate-rolling equipment to | | | | amounts of scrap.Quality rolling machines are |
| the specific needs of a manufacturer requires | | | | usually cambered at 50 percent of the |
| attention to detail. It is imperative that | | | | full-rated value of the machine. Hence, a |
| the dealer you work with is willing to sit | | | | 1-inch machine is cambered to roll 1/2-inch |
| down with you and discuss the specific needs | | | | plate at a nearly perfect edge.Disregarding |
| of your business. There are many issues that | | | | this important fact can result in out-of-spec |
| need to be addressed, many of which a | | | | product that the customer will not accept. |
| purchasing manager may not initially | | | | Problems most commonly arise when rollers |
| foresee.2. Factor in the properties of the | | | | attempt to push the upper limits of their |
| material to be rolledA metal's temper and | | | | plate roll. If 5/8-inch plate is rolled |
| yield strength must be matched with the | | | | through a 1-inch-rated machine, a small |
| customer's application to correctly determine | | | | degree of barrel effect will likely occur. |
| the specifications of the plate roller. This | | | | This may or may not be an acceptable margin |
| is especially important since steel | | | | for error.However, when plate thickness |
| characteristics have changed drastically over | | | | approaches the upper end of a machine's |
| the past couple of decades. What was once | | | | rating, then severe defects can occur. Unless |
| known as mild steel no longer exists.Even | | | | corrected with a shim, it will not be |
| though drawings call for a plate to be rolled | | | | sellable. Conversely, when very thin material |
| down to the same dimensions, a tougher | | | | is rolled through a machine rated for very |
| material will require a much higher-rated | | | | thick plate, the finished product may come |
| rolling machine. In absence of such | | | | out tighter in the center than at the ends. |
| considerations, defects will result and the | | | | Again, time consuming shimming is |
| manufacturer will end up with excessive | | | | necessitated to correct for this "hourglass" |
| scrap.Today's steel is much stronger and | | | | effect.Robert E. Heller is the current |
| requires more strength to bend. Thanks to | | | | President of E.G. Heller's Son, Inc. For more |
| detailed classifications by the American | | | | information about the proper selection of |
| Society of Mechanical Engineers, countless | | | | metal fabrication equipment contact, E.G. |
| varieties of steel abound: A36, A516 grade | | | | Heller's Son, Inc. |