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