The vertical side roll located at the outside of the bend is the outer side roll. The forming force from the outer side roll has the same direction as the bending action. It forms a better-quality bend than the conventional rolls in Figure 1. The vertical side roll located at the inside of the bend is the inner side roll. The function of the inner side roll is forming the desired radius at the bend.
The single roll design in Figure 3A cannot control the radius dimension because tooling cannot reach the inner corner. The double side roll design in Figure 3B forms the profile and the dimension more accurately than the roll design in 3A.
The side rolls, which are mounted in the same central line plane as the conventional rolls, are called stationary side rolls, as shown in Figure 3A and Figure 3B. The stationary side rolls and conventional rolls form a rotational extrusion head that squeezes the formed section from all directions: up, down, left, and right. This extrusion process provides strict control over the profile and dimension.
Single side rolls and double side rolls can be mounted before the conventional roll station (see Figure 3C). This arrangement allows more space for large side rolls.
