Scalping manner and scalping device null of hollow billet for metal extrusion

摘要

PURPOSE:To exactly and quickly scalp the inside and outside circumferential surfaces of a heated hollow billet and to decrease the off-centering of the inside and outside diameter by scalping the inside and outside circumferential surfaces of the billet in the longitudinal direction in the same scalping stage. CONSTITUTION:The hollow billet 34 is heated by a heater 50 and thereafter the outside circumferential surface thereof is scalped in the longitudinal direction of the billet by means of a pressurizing stem 24 for scalping and a scalping die 36. The billet is then charged into a container 51. A pressurizing stem 53 made into a cylindrical construction is provided via a push plate 52 to one side of the container 51 and a die device 54 for setting the outside surface shape of a pipe material is provided on the other side, respectively on the center line of extrusion. A mandrel 49 which is advanced and retreated by a cylinder device is inserted into the stem 53. The inside circumferential surface of the billet 43 is scalped by the chip part 55 of the mandrel 49 in the container 51.