EXTRUSION MOLDING DEVICE FOR ANNULAR BILLET

摘要

PURPOSE:To prevent the wear of a punch for extrusion molding by dividing said punch to an outer punch and inner punch, inserting slidably the inner punch into the outer punch and bouncing upward the inner punch by means of a spring so that the inner punch is acted with the downward force and slides against the spring force in the stage of molding. CONSTITUTION:The inner punch 3b is inserted into the bore of a billet 1 and the outer punch 3a contacts with the annular top surface of the billet 1 when the punch 3 is moved downward. The billet 1 is pressed by the outer punch 3a and the molding is started when the punch 3 moves further downward. The inner punch 3b descends first at the speed V of the outer punch 3a but the downward force acts on the inner punch 3b when a speed difference (mu-V) from the speed mu of the outflowing billet 1 is generated. The inner punch is thereby slid with the outer punch 3a by overcoming the force of the spring 4. The molding load is thus decreased and the wear of the inner punch 3b is lessened.