Research Of6061Aluminum Alloy Porthole Die Mandrel Stability

Porthole die plays a vital role in extrusion processing industry. The quality and service life of extrusion die are key factors that to determine the feasible of extrusion process and development of new product. And its structural parameters directly affect the quality of the products.In this paper,6061aluminum alloy pipe is analyzed. The porthole die are designed by using CAD software UG NX and the process of extrusion are simulated by FEM software Deform-3D. How the strain and stress of porthole die change in the process of extrusion under the different geometrical and technology factors was been obtained. Also the relationship between welding chamber depth and hydrostatic pressure, the relationship between mandrel stability and welded chamber depth, the extrusion speed, bearing length can concluded from the simulation.(1) In the welding surface, closer to the welding chamber edge, hydrostatic pressure is greater. With the depth of welding chamber increase, the hydrostatic pressure increase, and the growth rate slowed down gradually. The displacement of mandrel in extrusion direction decrease firstly and then increase when the depth of welding chamber increase. Different dimensions of the welding chamber has its proper depth.(2) With the extrusion speed increasing, the displacement of mandrel in extrusion direction will became more and more severe. Unsuitable extrusion speed can cause distribution of equivalent stress disorder, appear concentration of stress, result in the failure of die.(3) the displacement of mandrel in extrusion direction will became larger under the action of bearing length increase. The smaller working length will affect the stability of the hydrostatic pressure in welding chamber, and the bearing with itself is easy to abrasion. Both too long and too short length of bearing can cause the concentration of equivalent effective stress.