| 摘要 |
<p>643,857. Extruding. COMPAGNIEGENERALE DU DURALUMIN ET DU CIUVRE. Jan. 23, 1947, No. 2090. Convention date, Feb. 15, 1946. [Class 83 (iv)] A press for extruding tubes having a uniform internal diameter and an external diameter varying along the length of the tube comprises a circular die 10, and a mandrel having a conical part 4 adapted to be advanced through the die as extrusion proceeds, thereby causing an increase in the wall thickness of the tube which is expanded to a constant internal diameter by a cylindrical end portion 5 of the mandrel. The inner end of the mandrel is screwed into a piercing ram or mandrel holder 6 extending through a hollow pressing ram 7 or, alternatively may be fixed to the pressing ram. An oppositely tapered portion 3 facilitates the extraction of the mandrel from the residue of the billet.</p> |
