the 4 roll plate bending machine is the easiest one, thanks to a frame designed to satisfy every kind of needs. Advantages are various :
Pre-bending is highly reduced because the material gets pinched by in between the two central rolls.
Working can be made in one only pass, following the steps here below:
4. Closing pre-bending
The plate is fed into the machine horizontally thanks to the support of the lower roll (B) with the side roll (D).
The plate is automatically squared thanks to the position that the side roll (C) takes.
The space to the limit of the machine reduces to one side only, thanks to the possibility of
squaring and bending in one only step.
We advise a 4 roll plate bending machine:
For a high and massive production
For the possibility to control by CNC
For the possibility to make conical bends
Because it’s easy to use
When the machine is endowed of conical bending device, it would not allow the finished shell to be taken off. MG uses a unique system called contrast to eject the pipe. This particular system is composed of a piston mounted on the back side of the roll. This piston monitors the yoke position, when it’s completely down, the piston moves and lifts the top roll to let the operator eject the pipe without problems.
The monitoring is made by a valve, called sequence valve that “feels” the pressure increasing in the hydraulic circuit when the yoke opens, transferring it to the contrast piston that, consequently, lifts the roll.
In case the machine is CNC controlled, a pressure gauge is mounted on the sequence valve having the task of monitoring the pressure when the yoke closes. Reaching the set pressure by CNC, the pressure gauge will block the oil flow, stopping the pressure in the system.
If the choice of the machine has been made attentively, the minimum flat part you get will be 1,5 or twice the plate thickness. Even in this case, the plate thickness and its yield point, relating to the machine capability, make the difference.
Conical bending with a conicity over 4 degrees reduce machine performances. This is due to the unbalanced load on the top roll and its bearings. The more is the cone tilting the more the machine performance will decrease, till a maximum of a 50% in length and in bending thickness.