EFFECTS OF MANDREL SHANK POSITIONS AND THE GAP VALUES BETWEEN THE MANDREL BALLS AND THE TUBE ON THE THINNING AND THE OVALITY IN ROTARY DRAW BENDING

Tube and tube systems are very critical components to fulfill the design requirement of applications. Especially the bending radius is most important factor in a tube bending process. Therefore, as the bend ratio (bending radius/outer diameter of tube) and the wall thickness of the tube material decrease, the risk of encountering defects such as wrinkles, ovality, wall thinning, and crack increases. Rotary draw bending process is generally preferred for bending tubes with a small bend ratio and thin wall thickness. In this process, tools such as bend die, clamp die, clamp insert, pressure die, wiper die, and mandrel are used. For the minimum bending radius value can be accomplished considering the processes parameters such as material properties and geometry of tube, die geometries, position and geometry of mandrel, wiper die angle, pressure value of pressure die and bending speed. Bending of different tube materials by trial and error method results manufacturing cost and time increases. In this study, effects of mandrel shank positions and the gap values between the mandrel balls and the tube on the thinning and the ovality are investigated by commercially available PAM-STAMP program for AA6061-W condition material. The results are compared with available results in the literature.