Precision, versatility, and efficiency are key attributes needed by any business wanting to be competitive in the metal fabrication industry. In the plate rolling sector specifically, advancements in technology have transformed the hand-crank machines of yesteryear into hydraulic marvels that can build sections of space rockets with accuracies unheard of less than a decade ago. If you are looking to buy or upgrade the metal rolling machines of your shop, there are several plate roll options that you should consider incorporating into your current and future plate rolls.
Build the Right Roll
While many options certainly can be added to your existing plate rolls to help increase productivity, your best-bet as a shop owner is to make sure that you look closely at all optional accessories that can be included when custom-ordering a new plate roll directly from the factory.
You may feel like starting off small and upgrading later, but some improvements may require major rebuilds that would lead to additional costs (not to mention downtime) that could be avoided by building the right roll right off the bat. No matter how trivial each of the “bells and whistles” may seem, review each one carefully with your managers, operators, and other shop personnel to determine the added value they might bring to your upcoming scheduled and potential jobs.
A significant consideration when ordering a plate roll is the roll configuration. If you are buying a new three-roll machine, you likely won’t be getting a traditional pyramid roll, where the top roll moves up and down, but the bottom two rolls are stationary—forming a symmetrical pyramid shape between the three rolls when viewed end-on—as such machines are seldom manufactured these days in favor of more versatile designs.
The most common three-roll machine is the initial pinch asymmetrical plate roll, since such “IP” rolls have two rolls on top of each other that pinch the material as it is being loaded, and a back roll that is adjustable up and down. Double pinch plate rolls resemble pyramid rolls at first glance, but they have a stationary top roll and two bottom rolls that move down and away from the top roll, for greater control over the workpiece. Variable geometry plate rolls have a vertically moving top roll and horizontally moving bottom rolls.
While all the different arrangements of three-roll machines have their uses, it is worthwhile for serious metal benders to instead look at obtaining a four-roll plate roll for their shops. In these machines, the plate is securely kept in place between the top and bottom rolls while the side rolls independently move vertically to form the bend. Their design and operation make these plate rolls extremely accurate machines, especially when it comes to prebending. They are also extremely fast, since the operator doesn’t need to remove the material to prebend the trailing edge—the plate is loaded, the leading edge is pre-bent, the rolling operation then takes place in its entirety, with the trailing edge getting bent after the cylinder has been rolled.
Plate Roll Options to Improve Productivity
Here are some of the more commonly requested options for plate rolls that metal fabricators should consider:
- Cone Bending. If you roll cones, see if your brake can be built or upgraded with equipment to make this task easier. Some manufacturers will use angular contact bearings that shift in the bearing housings to allow the bottom and/or side rolls to be tilted to establish a tight cone. A cone shoe (or snubber) at the end of a top roll in 4-roll machines can rotate into position to keep the part in position while cone rolling.
- Control Unit. All plate rolls will have at least a DRO (digital readout), though many machines on the market will come with a simple PLC (programmable logic controller) to balance and direct the movements of the rolls. Upgrading the control unit to an NC (numerical control) or CNC (computer numerical control) will make machine management much more efficient. A mobile control panel and/or a wired or wireless remote control can be added to allow the operator to view the part from any angle during the operation.
- Crowning Compensation. Getting an optimal crown—or special roll crowning—machined into your rolls can help you avoid distorted parts due to deflection. Some 4-roll machines may have an option of adjustable hydraulic pressure on the bottom roll to help with crowning compensation.
- Lubrication. If you hate manually lubricating your plate roll, see if an automatic central lubrication system is an available option.
- Part Handling. A plate rolling job might need loading tables (idle or motorized), infeed conveyors, hydraulic drop ends, and part ejectors, not to mention side and/or overhead supports to help prevent distortion in large cylinders.
- Preventative Maintenance Program. While not a physical option for a plate roll, contracting with a machinery service company to provide regularly scheduled maintenance and inspections of your machine can be a very cost-effective add-on to keep you running at peak performance.
- Rolls. Hopefully your plate roll features highly durable carbon steel rolls, such as AISI 1050, but you may want to think about upgrading to high strength alloy steel rolls (such as AISI 4140). Getting rolls that are induction hardened will also help them hold up to wear and tear during rolling processes. In addition, you can order rolls that are ground or even polished if you need a mar-free finish on your rolled parts. You may also want an option of a changeable top roll to accommodate smaller diameter workpieces.
- Roll Drive System. Examine what drive systems are available for your choice in plate rolls. You may be able to get multiple powered rolls for better control of your workpiece, especially if a high-torque drive system is offered.
- Safety Features. All plate rolls sold today should have an emergency stop button on the control panel and safety wire surrounding the machine that will stop operations if triggered. Ensure that these are fully working on any new roll that you buy and that you know how to reset them. Any moving parts not directly contacting the workpiece may require safety covers to protect operators and bystanders. Electrical and hydraulic overload protection is also an important feature that can mitigate harm to operators and equipment.
- Temperature Control. For better performance, you may want to examine getting an oil cooler and/or an oil heater for your plate roll. Some manufacturers can also provide air conditioning for electrical panels.
- Variable Speed Control. Dual speed control (through an NC control) or variable speed control (through a CNC) may be available for some or all axes, giving the operator greater control of the workpiece during rolling.
- Welding Options. If welding will be performed on the cylinder while it is still in the machine, great care needs to be taken. If welding is performed near the plate roll’s controls, the welding power source could damage or destroy them. Fabricators need to ensure that the welding ground is always on the part, never on the machine. Options will usually exist to upgrade the plate roll to a shielded electronic system just to be safe.
Talk to your metalworking machinery provider right away to see what aids to productivity can be upgraded on your existing plate rolls or added to your next new plate roll investment.
