Although the number of three-roll plate bending machines on the market is increasing today, 4-roll plate bending machines are gradually gaining a dominant position in the sheet and sheet metal manufacturing industry due to their universal advantages.
While the three-high asymmetric initial pinch roll is still the first choice for rolling light-duty sheet metal, the four-high roll is a better choice for rolling plates from 10-gauge steel to several inches thick.
Due to the advanced mechanism and larger capacity of 4-roll plate rolling machines, most manufacturers can add a variety of options and accessories to make these 4-roll plate rolling machines even more efficient. Higher quality components such as hardening and grinding rolls are often available if not included in the standard features. An automatic feeding station can keep the rolls turning by preloading the next plate while the current plate is being rolled. Hydraulic side supports and overhead supports help plate rolls accommodate larger diameter finished parts. The design of the four-roll rolling machine makes the workpiece very safe, allowing the addition of NC and CNC units. Combined with a 30% investment in machine cost, manufacturers can have a plate roll that can increase productivity by 70%.
The 4-roll plate rolling machines offer greater precision primarily due to their unique material-holding capabilities, which are not found in their 3-Roll plate rolling machines cousins. This constant squeezing and driving of the workpiece mean accurate tracking throughout the bending cycle, from the initial loading of the metal to the removal of the finished part. Using a rotary encoder to track the exact position of the plate allows the addition of an optional CNC unit for very precise control of each stage of the rolling process. The side rollers are on their own independent axes, allowing for greater precision.
The extra rolls on the 4-roll plate rolling machine make cone rolling easier. Manufacturers often use angular contact bearings that move in chocks to allow the bottom and side rollers to tilt to create a tight cone. Four-roll plate rolling machines are usually equipped with a cone shoe (buffer) that rotates to the end of the upper roll and holds the part in place while rolling the cone.
Because they are used for more demanding jobs, good 4-roll plate rolling machines are built with heavier reinforced steel frames and feature top-of-the-line components. The best manufacturers will use industry-approved parts that can be easily replaced off-the-shelf from local suppliers around the world, rather than having their customers wait for factory-specific replacement parts to ship.
Easy to operate
Most operators consider the 4-roll plate rolling machine to be the easiest to learn and the easiest to use. Because the sheet is firmly clamped during the straightening process and held in place throughout the operation, newer manufacturers can perform functions such as pre-bending and tapering with the precision of an experienced coil operator rolling.
Most modern pyramid plate rolling machines have side rolls that move up and toward a fixed top roll. They are driven by “planetary” or “linear” guides, hence the name for the way the rollers move. Planetary guides move in an arc toward the upper roller (much like the curved orbit of a planet), while linear guides move in a straight diagonal line toward the upper roller. Some manufacturers will choose the other, but high-end producers of 4-roll flat rolls often offer both machines, usually with planetary systems and larger rolls for the smaller rolls (top roll size 17 inches or smaller). Large rollers and straight ones. Some even build custom machines to the buyer’s preferences, so it’s good to know the pros and cons of both systems. Linear guides can provide greater power to pre-bend and roll thick plates.
Four-roll coilers are “dual initial pinch” machines, which means they can be fed from either direction. Plates are loaded horizontally into 4 roll plate rolling machines – even when pre-bending is taking place – which allows the use of roller tables to support the plates. For a three-roller machine, if pre-bending is required, the plate must be fed downward at an angle, which is a tedious process. Since the bottom roller on the 4-roller can be raised to support the plate during loading, the “back” roller (the one furthest from the loading point) can be moved up to act as a kind of backstop to accurately adjust the printing plate. the orientation of the version. The plates are properly aligned. This squaring capability eliminates the need for additional human assistance during loading. The constant clamping of the upper and lower rollers on the workpiece ensures the safety of the workpiece from the loading process to the end of the operation.
Once the material has been at right angles to the side rolls furthest from the loading point, and the bottom roll has been raised to clamp it firmly to the top roll, the workpiece is set back slightly so that its edge is exactly on the centerline of the top and bottom roll. The side roll closest to the loading location is then lifted to create a fairly tight pre-bend in the material. When the plate is rolled into a cylinder, the side rollers can be raised and lowered as needed. Unlike 3-roll, after pre-bending the leading edge, there is no need to immediately remove the board from the 4-roll to pre-bend the trailing edge—the process happens at the end of the bending cycle, while the part is still sandwiched between the top and Bottom roll, usually all in one operation.
4-roll plate rolling machines are more productive in the workshop compared to 3 rolls. Spend your precious time pre-bending both ends of the sheet before the actual rolling cycle of 3 rolls. With 4 rolls, once the sheet is loaded and sandwiched between the upper and lower rolls, the sheet never leaves the machine, and some bending cycles are done only once. By keeping the workpiece in the machine during operation, efficiency can be increased by up to 50%. This also reduces the need for additional personnel to assist the operator. Loading steel plates horizontally eliminates the need for a crane, and using a feed table for material handling allows for pre-loading of the next steel plate while the current steel plate is being rolled.
Four-roll plate rolling machine is the safest rolling machine. Horizontal charging is safer than the angle charging required by most three-rollers. Even with just one operator, the ability of the board side makes loading foolproof. The continuous pressing of the material by the upper and lower rollers not only keeps the workpiece firmly in place throughout the bending process but also the position of the plate can always be tracked very precisely with constant feedback to the PLC or other controls. No need to remove, Pre-bending the second edge by rotating and right-angling the board again removes many of the potential hazards of the material handling portion of the operation.
The ability to upgrade the 4-roll plate rolling machine to a CNC machine not only adds better control and accuracy to the bending operation but also makes coiling more versatile. The CNC plate bending machine can easily bend challenging contours such as rectangular, oval, or polycentric shapes, an important feature for creating non-cylindrical tanks. The 4-roll is convenient in workshops with limited floor space because the workpiece is rolled up and turned over immediately after the first prebend, so the machine can be placed very close to the wall (and since it can be fed from either side) 4 rolls, it doesn’t matter which direction the machine is facing if it’s close to the wall)
The definition of the direction axis of the bending machine is slightly different from that of the bending machine. The diagonal movement of the outer rollers is generally considered to be the X and Y axes, while the vertical movement of the machining center is the Z axis. The 4-roll plate rolling machine’s additional lower roll is capable of moving up and down the Z-axis to clamp material on the upper roll, providing incredible plate control. This allows for better prebend and tighter part diameters than the previous use of 3-roll sheet rolls that lacked Z-axis clamping.