Technical Instructions: 
The traditional three - roll bending machine usually adopts the method of lower row double-roll feeding and upper roll hydraulic cylinder controlling diameter adjustment.
This method is limited by small feeding friction, and it is not suitable for bending with small diameter. During the bending process of raw materials , it is difficult to ensure the consistency of forming diameter due to uneven stress.
The four - roll bending machine adopts a set of oppositely clamped feeding roller for feeding the pipes. This feeding form ensures that the pipe can bear sufficient and uniform friction during the spiral forming process. Especially in the manufacturing process of multi - coil spiral coil , the consistency of each coil diameter can be maintained to the maximum calibration of finished parts is extent, and the not required.