On the Forming Load and the Forming Torque in Forming a Groove with Wide Flanges by Cold Roll Forming

Abstract

The effect of forming conditions on the forming load and the forming torque of sheet steel in forming a circular arc groove with wide flanges has been experimentally investigated by changing several factors. It is found that both the forming load and the forming torque are in proportion to the (2+n) power of the thickness of the specimen (n＝index of work hardening of the specimen) ; and they increase with the increase in the width of the specimen, ranging from the length measured along the roll profile to twice this length. Also, they have constant values for a width of specimen over twice the length measured along the roll profile, and increase symmetrically with the increase in the absolute value of the inlet angle of the specimen, ranging from -4° to +4°. Finally, they have proportional relations mutually. The forming load is hardly affected by the ratio of surface velocities of the flat parts of rolls and the ratio of maximum convex to minimum concave roll diameters. However, the forming torque is greatly affected by the ratio of surface velocities of the flat parts of rolls. On the basis of the experimental results mentioned above and the theory of the plastic bending of plate, an equation for estimating the forming load was experimentally formulated. The calculated forming load from this equation is in good agreement with the experimental results, and the difference between both loads is at most 10%.Furthermore, the forming load of sheet steel in forming a trapezoidal groove with wide flanges by a tandem roll forming was estimated by a die pressing method with sufficient accuracy.