Both 4-roll and 4-roll plate rolling machines are popular sheet processing equipment in the market, and when your shop needs a new plate rolling machine, you may be wondering, which one should I choose, three-roll and four-roll after all It’s not like the accelerator and brake functions in a car are very different.
When choosing what type of machine, it is important to understand what type of output each machine is capable of creating and what finishing processes need to be done manually.
Choosing the right plate roller for your machine shop or metal fabrication business requires understanding their differences and their unique features, uses and benefits. Here we provide the detailed differences between three-roll and four-roll plate bending machines for your reference.
The 11 Differences Between The 3-Roll and 4-Roll Plate Rolling Machine
Pre-bending on a 3-roll plate rolling machine requires tilting the sheet down while feeding, which is a tedious process. In contrast, metal sheets are loaded horizontally at the feed level for pre-bending on a 4-roll plate bending machine, allowing horizontal motorized roller tables to help feed the sheets.
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 appropriately aligned. This squaring capability eliminates the need for additional human assistance during loading. The continuous 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.
The 3-roll plate rolling machine is manual unloading, and the processed workpiece needs to be unloaded manually. The 3-roll plate rolling machine is controlled by buttons, which is convenient and quick to unload and is much safer than the three-roll plate rolling machine.
The three-roll symmetric plate rolling machine is symmetrical with one roll on the top and two rolls on the bottom. The three-roll asymmetric plate rolling machine is asymmetric with two rolls on one side and one roll on the other side.
The difference from the 3-roll plate rolling machine is that the upper roller of the 4-roll plate rolling machine is the main drive, and is connected to the upper roller through a reducer and a cross-slide coupling to provide torque for the rolled plate; The machine worm and worm gear (bevel gear) is obtained by attaching the threaded mother screw to clamp the plate for mechanical transmission; there are side rollers on both sides of the lower roller and make a tilting movement along the rack guide rail, through the threaded worm screw and worm wheel (or bevel gear) transmission.
The four-roll plate bending machine can effectively utilize NC and CNC control, and the bending of complex shapes such as multi-center or oval workpieces can be easily accomplished with the CNC four-roll plate bending machine. Side rollers move vertically to create accurate bends easily, intuitively, and quickly.
Degree of automation
The three-roller plate bending machine has simple control with buttons; the four-roller plate bending machine has a touch screen, and the CNC system can be programmed.
The four-roller plate bending machine is digitally controlled, one-time rolling, and the touch screen supports visual input, editing rolling plate process steps, and storing 500 sets of data. EPS electronic balance system keeps the rollers moving parallel within 0.15mm. Support man-machine dialogue, fault self-diagnosis, the intelligent judgment of operation errors, drum-shaped roller shaft, good rolling roundness, and high straightness.
The working principle of the three-roll and four-roll plate rolling machines is the same, and the three-point circle principle is used for rolling with different radii. However, the straight edge pre-bending and the roundness of the rounding of the four-roll plate rolling machine are better than those of the three-roll plate rolling machine.
Most of the three-roll plate bending machines are mechanical plate bending machines, and of course, there is hydraulic plate bending machines, but all four-roll plate bending machines are hydraulic plate bending machines.
Because most of the three-roll plate bending machines are mechanical plate bending machines, the processing efficiency of the motor is also low, and many processes require manual cooperation, so the work efficiency will be relatively low.
Because the four-roll plate rolling machine is a hydraulic plate rolling machine and is controlled by numerical control, the processing efficiency of the motor is high, so the overall work efficiency is also much higher, and the workpiece output rate is much higher than that of the three-roll plate rolling machine.
With 4 roll plate rolling machine, 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.
Valuable time is spent pre-bending both ends of the sheet before the actual rolling cycle on the 3-high press brake. Keeping the material in the machine makes the 4-roller 50% more efficient than the 3-roller and allows the cylinder to be rolled to the desired diameter immediately after pre-bending.
The processing accuracy of the three-roll plate rolling machine is general, which can meet the basic needs of most factories. The four-roll plate rolling machine has higher processing accuracy, and can also process workpieces with special shapes such as cones, this allows for better prebend and tighter part diameters than previously used 3-roll plate rollers that lacked Z-axis clamping.
The higher precision offered by the 4-roll plate rollers is mainly due to their unique material-holding capabilities, which their 3-roll bending machines do not have. This constant squeezing and driving of the workpiece means 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.
4-roll Sheet Metal Rolling Machine horizontal loading is safer than the angular loading required on most three-roll plate bending machines, and the ability to square the plate makes loading foolproof, even with only one operator.
Once the material is set and clamped, the two rollers on either side of the clamping roll do all the work without removing the plate and rotating it to pre-bend the ends, eliminating many of the potential hazards of the material handling part of the operation.
Under the same rolling capacity, the price of the three-roll plate bending machine is necessarily lower than that of the four-roll plate bending machine, because the accuracy and working efficiency of the three-roll plate bending machine are lower than those of the four-roll plate bending machine. If the frequency of use of the machine is not high and the accuracy requirements of the workpiece are not high, you can choose a three-roll plate rolling machine with a lower price; but if the product requirements are high, a more cost-effective four-roll plate rolling machine is recommended.
Read More: Bending Machine Wikipedia
4 rolls vs. 3 rolls
- Four roll bending machines are more precise, productive, versatile, faster, safer, and easier to operate than three roll machines. They are less dependent on operator competence.
- The fastest and most accurate bends are made by four roll machines. The 4 roll machines have a slight advantage in cycle time because they permit pre-bending of the leading edge, rolling the cylinder body, and finishing off the trailing prebend, all while rolling in the same direction.
- The bottom roll moves up to hold the workpiece securely against the top roll while the side roll is raised to form an accurate pre-bend, minimizing the flat zone on the workpiece edge. Pre-bending on a 3-roll bending machine requires that workpieces be tilted down as they are being fed. In contrast, workpieces are loaded horizontally at the feed level for pre-bending on a four-roll machine, which allows the use of horizontal motorized roller tables to help feed the workpiece.
- The side rolls are positioned to the right and left of the bottom roll and are on their own axes. The independent axis of each roll helps make a perfect bend.
- The workpiece is kept square without slipping during both pre-bending and rolling because of the constant secure clamping of the top and bottom rolls.
- Cone rolling is easier on a four-roll 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 workpiece.
- 4-roll benders are better suited to have CNC controls since the material is held between two pinch rolls and the position can be controlled. Because of the constant clamping and driving of the material during all steps of rolling, bending difficult shapes like polycentric or elliptic workpieces can be easily done with 4 roll bending machines.
Who is the best three-roller or four-roller bending rolls?
4 roll plate rolling machine are more precise, productive, versatile, faster, safer and easier to operate than 3 roll plate bending machines. They are less dependent on operator competence. One of the main decision factors you should consider is not only the type of rolling machine that will meet your current needs, but possibly future business needs as well.