Patent ID: 8956559
Filing Date: 2015-02-17
Classification: B29C,B29K,B29L

Abstract:
1. A method for forming an extruded tubular member having a three-dimensionally curved shape and two or more different radiuses of curvature, which comprises: introducing a material into an extrusion die having an extrusion orifice, the extrusion orifice having an inner circumferential surface that is disposed at an opening-side of the extrusion orifice and has a circular section, and a core-side die disposed concentrically with the extrusion orifice, the core-side die having a distal end portion terminating in an inclined plane which results when a circular cylinder is cut obliquely through an entire cross-sectional area of the circular cylinder; continuously extruding a tube of the material through an extrusion passage defined between the inner circumferential surface and an outer circumferential surface of the core-side die; and bending the extruding tube material by changing contact areas where the extruding tube material contacts the inner circumferential surface and the outer circumferential surface in a circumferential direction and setting velocities at which the tube material is extruded through the extrusion orifice to different values in the circumferential direction while adjusting positions of the inclined plane of the distal end portion of the core-side die in rotating and axial directions relative to the extrusion orifice using a die position control mechanism.