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Top 10 benefits of 4 roll plate rolling machines

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The 4-roll plate bending machine is a metal plate bending device with a digital display, allowing users to see side rolls. The 4-roll plate roller has electro-hydraulic calibration and safety equipment all around. The 4-roll machine can make a metal fabricator’s day at work much easier and improve business efficiency.

In spite of the continued proliferation of three-roll bending machines in the market today, four-roll plate rolls are steadily becoming more dominant in the plate and sheet metal fabrication industry because of their general superiority.

Here’s a guide to the top 10 benefits of a 4-roll plate rolling machine:

Easy-to-operate 4 roll machines

Because the plate is clamped securely during the squaring process and held throughout the operation, newer fabricators can perform various functions such as pre-bending and cone rolling with the precision of seasoned plate roll operators.

4 roll plate roller machines are advanced bending and rolling machines as they are more precise, productive, versatile, faster, safer, and easier to operate than 3 roll plate rolling machines as they are less dependent on operator competence.

A four-roll machine is easier to operate for anyone new to plate rolling. First, it’s easier to load the plate into the machine than in a three-roll machine because the rear bending roll can be used like the back gauge of a shear.

The operator lifts the rear bending roll as the plate is being loaded into the machine and moves the material until it hits the rear bending roll in the center, squaring it up like a press brake operator would do with a workpiece and the back gauge. The bottom roller is then brought up to pinch the material. With this four-roller arrangement, the material is held by the rollers for the entire bending sequence.

Abundant accessories to enhance plate rolling efficiency

Because of the advanced mechanisms and larger capacities available in 4-roll machines, most manufacturers have a wide range of options and accessories that can be added to give these machines even greater efficiency. Higher quality components, like a changeable top roll for small diameters, are usually available, if not included as standard features.
Special rolls with contour, grooves, etc, to allow bending plates with flanges and/or ribs. Side supports and top support with electric or hydraulic operation help plate rolls accommodate larger diameter finished parts. The design of a 4-roll plate roll keeps a workpiece very secure, allowing NC and CNC units to be added. With an additional 30% investment over the cost of the machine, fabricators can own a plate roll that can give them up to 70% more productivity.

Accuracy and bending of difficult shapes

4-roll plate rolling machines can effectively make use of NC and CNC controls because of the constant clamping and driving of the material during all steps of rolling, this constant pinching and driving of the workpiece from the initial loading of the metal to the removal of the finished part means that accurate tracking is available throughout the bending cycle. Can give very precise control of each stage of the rolling process and bending difficult shapes like polycentric or elliptic workpieces can be easily done with CNC four-roll plate rolling machines. The side rolls move vertically to create an accurate bend easily, intuitively, and quickly.

Cone rolling is much easier

Cone rolling is easier on a 4 roll plate rolling machine. The side rolls can be tilted to establish the cone angle and the bottom roll can also be tilted to clamp and drive the plate. 4-roll plate rolling machines will usually feature a cone shoe (snubber) that can rotate into position at the end of the top roll and keep the part in position while rolling cones. Through superior construction and design, a massive heavyweight body and the ability to angle bottom and side rolls the 4 roll plate roller can bend wide angle and small diameter conical parts with ease, with minimal effort from the operator.

Rectilinear and planetary guides

Planetary guides move in arcs toward the top roll (much like the curving orbits of planets), while rectilinear guides move in a straight diagonal line towards the top roll. Some manufacturers will opt for one over the other, but higher-end producers of 4-roll machines will usually offer both, often outfitting smaller plate rolls (those with a top roll size of 17″ or smaller) with planetary systems and larger rolls with rectilinear ones.

  • The linear guide’s design is the only system that can grant the necessary machine stiffness and the perfect geometry for all kinds of bending operations.
  • The linear design allows a compact geometry of the machine (“minimum centerline distance between the two side rolls” impossible to obtain with the swinging design) that it is essential for the bending precision and accuracy.
  • The linear design allows working in the best and ideal geometrical conditions when rolling high yield strength materials, reducing the shell spring back reopening effect and also allows to obtain much smaller bending diameters when compared with the swinging design.

Rectilinear guides can provide more power to prebend and roll heavy plates, while planetary guides with their curved paths reduce spring back, create near-perfect pre-bending, and allow tighter diameters in lighter material.

Basis of good 4 roll machine

The good 4 rolls use a unique machine frame, with extended design for added rigidity and strength, are welded fabrication. After welding, all frames are stress relieved and then machined on CNC milling.

Heavily gusseted massive steel frames form the basis of 4 roll plate roller, to be used for more demanding jobs.

The best manufacturers will use industry-recognized parts that can be easily replaced off-the-shelf from local suppliers worldwide, rather than holding their customers hostage waiting for factory-specific replacement parts to be shipped.

Easy Material Loading

4-roll plate rollers are “double initial pinch” machines, meaning they can be fed from either direction.

Pre-bending on a 3-roll bending machine requires that plates be tilted down as they are being fed, which is a cumbersome process. In contrast, metal plates are loaded horizontally at the feed level for pre-bending on a 4 roll bending machine, which allows the use of horizontal motorized roller tables to help feed the plate.

Plate feeding can take place on either side of a 4-roll bending machine. If fed from only one side, they can even be placed close to a wall to save floor space.

Since the bottom roll on a 4-roll can be raised to support the plate during loading, the “back” roll—the one furthest from the point of loading—can be moved up to function as a sort of back gauge to accurately square the plate for proper alignment. This squaring function removes the necessity of having an extra person assist during loading. The constant clamping of top and bottom rolls on the workpiece keeps it secure from the loading process through to the end of the operation.

Excellent per-bending effect

The use of the extra bottom roll on 4 roll bending machines greatly minimizes the flat area on plate edges during pre-bending.

Four roll machines do not require the operator to remove, flip, and then try to square and reposition the plate a second time after pre-bending, as is the case with 3-roll plate rollers. Keeping the material in the machine makes four rolls 50% more efficient than 3-roll plate rolling machines, and allows a cylinder to be rolled to the required diameter immediately following pre-bending.

Pre-bending process

Once the material has been squared against the side roll furthest away from the loading point and the bottom roll has been raised to firmly pinch it against the top roll, the workpiece is backed out slightly so that its edge is just at the centerline of the top and bottom rolls. The side roll closest to the loading position is then raised to create a fairly tight prebend in the material. The side rolls can then be raised and lowered as needed as the plate is rolled to form a cylinder.

Bending the back edge takes place after the cylinder is rolled, for a one-direction, single-pass operation(often with everything done in a single-pass operation).

Higher productivity

Four roll plate rolls are more precise, productive, versatile, faster, safer, and easier to operate than three roll machines. They are less dependent on operator competence.

With a 4-roll, the plate never leaves the machine once it’s been loaded and pinched between the top and bottom rolls, and some bending cycles can be completed in just one pass.
Valuable time is spent pre-bending both ends of a plate prior to the actual rolling cycle on a 3-roll bending machine. Keeping the material in the machine makes the 4-roll plate bending machine 50% more efficient than 3-roll plate bending machines, and allows a cylinder to be rolled to the required diameter immediately following pre-bending.

Loading plates horizontally can eliminate the necessity of a crane and using an infeed table for material handling allows the next plate to be preloaded while the current plate is being rolled.

Safer Plate Roller

4-roll plate bending machines are more productive, precise, safer, versatile, and easier to operate than the rest.
Horizontal material loading is safer than the angle loading required of most 3-roll plate bending machines, the ability to square the plate makes loading foolproof, even with one operator.
Once the material is set and pinched the two rolls on either side of the pinched roll do all the work without having to remove the plate and rotate it for pre-bending both ends, eliminating many potential hazards from the material handling portion of the operation.