Lower roll pressurized → Feeding work and edge bending → Roll rotates → Lower roll move down and complete
The steel cylindrical bending process by urethane roll is using the performing of lower urethane roll by pressurizing from upper roll (steal). by work is pressed and rotate between urethane roll and upper roll wtih pressure for processing. For changing work diameter size, it required to change upper roll diameter or installing the forming ring.
Urethane, Two Roll
These rolls tend to work well in high-volume environments with thin-sheet applications, usually 3⁄16 in. and less. In this setup, a mandrel (also called a spindle pipe) mounted on roll A determines the cylinder radius, so if you need to roll a different radius, you need to change out the mandrel. Once set up, though, operation is simple. You raise roll B against roll A, square the plate against the two rolls, and then execute the rotation.
Driven roller Ⅱ, Ⅲ is driven by motor and reducer, which rotates in the same direction at the same speed (or in the opposite direction).
Because of the friction between the roller and the plate, the plate is driven forward and the roller is rotated.
Adjust the position of the upper roller properly, and the roll of different curvature of the plate can be made.
If the workpiece cannot meet the desired curvature after a rolling process, the upper roller can be reduced properly, and then make the reverse rolling again and again until it is rolled into the desired shape.
As can be seen from the above figure, the three rolls of the symmetrical three roller bending machine are arranged in an isosceles triangle, so in the rolling process, the two ends of the workpiece are bound to leave a straight line.
The length of the straight-line segment is about half the distance of the center of the two lower rollers. This part of the straight line is the place where the roller cannot roll, which is the biggest disadvantage of the symmetrical three-axis roller.
Despite the disadvantages of the symmetrical three roller plate bending machine, it has been widely used because of its simple structure, convenient operation and low cost.
As for the problem of eliminating the straight-line segment, it can be solved by different methods in combination with the specific situation, as shown in the table below.
|Elbow pre-bending||This method uses the die to prebend two ends of the steel plate at the pressure machine to achieve the desired curvature.|
|Keep allowance||Add appropriate plate allowance at plate ends. After the two ends roll out a certain length, then cut off the remainder (also known as the straight-line segment).|
|Add base plate for pre-bending||This method is performed on the roll machine, as shown in figure 3b.|
However, when this method is adopted, the ability of the rolling machine should be fully considered, that is, the sum of the bending force of the work and the required gasket should be less than that of the roll plate machine.
Initial Pinch, Three Roll
One of the most common plate rolling configurations, the initial-pinch system entails introducing the plate to the rolls so that roll A and B grip the part, while roll C performs the first prebend. Next, you turn the material 180 degrees and insert the plate to prebend the other edge. Then, you use all three rolls to close the cylinder.
Double Pinch, Three Roll
In this setup, you first lower roll C and raise roll B, then introduce the plate between A and B. Once the plate is gripped, you raise roll C to form the first prebend. Next, you pass the roll through the machine so that the plate is gripped between rolls A and C, then raise roll B to perform the second prebend. Finally, you position the rolls in a standard pyramid configuration and roll the cylinder.
Double Pinch, Variable Geometry
Unlike any other plate roll type, the variable-geometry variety offers a top roll that is not fixed, but instead moves up and down. In this arrangement, you introduce the plate, and then move rolls B and C horizontally so that roll B is almost directly under roll A. You bring roll A down to form the first prebend on one plate edge, then feed the plate through and move the bottom rolls horizontally so that now roll C is almost completely under roll A. Roll A descends to perform the second prebend. Finally, you position the rolls in a standard pyramid to roll the cylinder.
The steel plate is placed between the upper and lower rolls, and the upper and lower rolls sandwich the steel plate.
The one side roll is raised and the steel plate is placed against the side roll to align the sheets.
The roller rotates to bring the steel plate to the pre-bending position, and the end of the plate is at the center line of the upper and lower rolls.
The side roller rises to bend the end of the sheet.
The end curvature is measured, several times, and pre-bent to the desired curvature.
Adjust the side roller position, one side of the roller is lowered, and the other side of the roller is adjusted to the plate.
The roller is rotated and rolled, and the position of the side roller should be adjusted during the winding.
In this position, the other end of the plate is pre-bent and the barrel is formed
Double Pinch, Four Roll
These machines are known for their speed, mainly because the workpiece doesn’t have to be removed before rolling to perform the second prebend.
You introduce the plate, and the machine grips it between rolls D and C. Roll A then moves up for the first prebend.
The system then forms the cylinder, after which roll B raises up to perform the second prebend.
copyright © Borisbang Industrial Technology (BIT) 2019