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