The roller leveller is a machine that uses two rows of straightening rollers arranged in opposite directions to repeatedly bend and straighten the rolled material to correct its curvature. It is mainly used to straighten steel pipes and eliminate defects such as longitudinal curvature and non-circular cross section after the formation and welding of the steel pipes, as well as to eliminate the organization stress of the steel tube weld seam caused by welding high temperature.
The principle of the roller levellers is that the size and direction of the original curvature of the metal is different. The roller levellers repeatedly bend the metal to eliminate the unevenness of curvature, so that the curvature becomes smaller and the metal becomes straight. In the roller levellers, there are two correction schemes based on the deformation amount (pressing amount) generated by each roller on the metal: small deformation correction scheme and large deformation correction scheme.
The small deformation correction scheme assumes that each roller on the upper row of working rollers of the straightening machine can be adjusted separately, and the adjustment principle of the pressing amount of each roller is that after the metal entering the roller, the maximum original curvature of the metal should be completely eliminated by rebound and bending, so that the metal in this position becomes straight.
The large deformation correction scheme is often used in production due to the changes in the original curvature of the metal and the difficulty in accurate determination.
According to the different purposes and structures, the roller levellers can be divided into plate straightening machine, section steel straightening machine, and oblique roller levellers for pipes and bars. The roller leveller is mainly composed of components such as electric motor, reducer, gear seat, connecting shaft, and straightening roller work seat.
Plate straightening machine: According to the arrangement method and adjustment method of the straightening rollers, there are various types such as parallel roller levellers, adjustable straightening roller deflection straightening machine, and inclined roller levellers.
Parallel roller levellers: The upper and lower rows of straightening rollers of the parallel roller levellers are arranged in parallel, and the lower rollers are fixed while the upper rollers can be adjusted independently.
Inclined roller levellers: The lower row of rollers of this roller leveller is fixed, and the upper row of rollers is installed in an adjustable upper frame, and the upper rollers can be adjusted to be inclined at the same angle as the lower rollers.
Oblique roller levellers for pipes and bars: The roller leveller for straightening pipes and bars is usually called an oblique roller leveller. The straightening rollers of the oblique roller levellers are inclined, and when the pipes or bars enter the straightening machine, they not only move forward but also rotate. The pipes or bars undergo repeated bending and deformation by several rollers to become straight. The oblique roller levellers can be classified according to the number of rollers, such as three rollers, five rollers, six rollers, and seven rollers, etc.