Study On The Extrusion Process Of Bimetal Tube With Middle Or Small Caliber And Thin Wall Thickness

Bimetal tube can satisfy the demand of more than one performance because it hasproperties of two metals. So it is widely used in the field of automobiles, electric equipment,electric power, metallurgical equipment, shipbuilding and so on. Aluminum-copper cladcomposite tube is largely used as condenser in the electric field such as refrigerator and airconditioning because it has the corrosion-proof property of aluminum and the conductive,thermal property of copper.In this paper, the extrusion process of bimetal tube has been simulated based on thestructure of traditional extrusion die. From the simulation results, we verified the die structureand proposed the die structure with 1/4 tangent arc occurred at the end of cone angle ofconcave and the die structure with contact angle occurred in the punch. The equivalent stressand equivalent strain of the billets in the extrusion process have been analyzed. It canconclude that the reason the inner billet happen to crack is not the large lateral extrusionpressure to the inner billet from the outer one in extrusion process. The reason may be theresults of the smaller hardening of the inner billet or the velocity deviation of the two billets.Through the reverse thinking, the die structure with a cone angle of mandrel and a holeconcave is proposed. It is found that the inner billet still generates the fracture when thethickness ratio of two billets is 1:1 by FEM. But the good bimetal tube is obtained when thewall thickness of inner billet is increased. Based on the velocity deviation of two billets,another structure is proposed. The structure is that both the concave and the mandrel have thecone angles. The velocity field, equivalent strain distribution, the scheme of load and strokeare also analyzed.In this paper, the die equipment structure is provided. The physical experiment has beenoperated. The problems occur in the extrusion process have been analyzed.