A Study on the Welding Pressure of Extrusion Processing of Hollow Tube Using the Porthole Die with the Different Chamber Shape

포트홀 다이를 이용한 중공튜브 압출 제품의 다이 챔버 형상에 따른 결합력에 대한 연구

The welding pressure in porthole die extrusion is affected by the shape of welding chamber. It is very important to increase the welding pressure when the tube is used particulary as the materials of hydroforming processing. The high circumferential stress of the tube would make the welding pressure increase during the porthole die extrusion. In order to increase the circumferential stress, it is necessary to make the billets pass through the narrow gap between the conical die and the conical mandrel. This paper describes the welding pressure by the experiments with the two types of the chamber. One of them is the chamber between the flat die and straight mandrel, and the other one is the chamber between the conical die and conical mandrel. The result of the experiments show that the conical chamber makes the welding pressure increase by the effect of the reducing the diameteres of tube.