Bending Galvanized Steel Tubing
In compression bending, the work piece is clamped to a bend die (or radius block). A wipe shoe (or slide block) is then brought into contact with the work piece. As the wipe shoe rotates around the static bend die, it forces the work piece to assume the radius of the bend die. This type of bending represents certain advantages for bending of open extrusions and shapes.
A ram die with the desired radius of bend is fitted to the press arm. The arm forces the tubing down against the opposing two wing dies. The wing dies, with resisting pressure, pivot up, forcing the tube to bend around the ram. Press bending is very fast and may bend more miles of tubing than any other method. Since the tubing cannot be internally supported, considerable distortion can occur.
Rotary Draw Bending
Rotary draw bending may be the most versatile, precision system of bending. It certainly produces high quality bends on the tightest radius within thin wall tubes. With a heavy walled tube on a generous radius, only a three piece family of tools is required. The work piece is locked to the bend die by the clamp die. As the bend die rotates the follower type pressure die advances with the tube. As the wall of the tube becomes thinner and/or the radius of bend is reduced, a mandrel and a wiper are required.