GB837126A - Hydraulic metal extrusion press with movable mandrel - Google Patents

Abstract

837,126. Extruding. LOEWY ENGINEERING CO. Ltd. July 12, 1957, No. 22237/57. Class 83 (4). An hydraulic metal-extrusion press has a movable mandrel 34 actuated by a piston 31 working in a cylinder 30 built into the main press ram 11 and an hydraulic mandrel-arresting device 40 comprising at least one cylinder 41 connected by conduits 45, 46 with the return space of the cylinder 30 and containing a piston 42 which projects out of the cylinder 41 and is engageable by a stop 43. Preferably a pair of mandrel-arresting cylinders 41 are carried in a crosshead 15 secured to the main ram 11 which actuates the pressing stem 14 and press disc 16. The stops 43 are adjustable and are mounted on a holder 21 for the billet container 20 or alternatively on the press bolster or on the main cylinder 10. Alternatively the stops 43 may be carried by the crosshead 15. In operation a hollow billet is pushed into the container by the stem 14 and disc 16. The mandrel 34 is then advanced through the billet into the orifice of die 22 by pressure-fluid admitted to the rear of piston 31. This forces fluid from the front of piston 31 into cylinders 40 whereby pistons 42 move forwardly until they engage stops 43. The main ram is then advanced to extrude the billet whereby the cylinders 40 move over the now stationary pistons to force pressure fluid to the front end of cylinder 30, thus keeping the mandrel stationary during extrusion. An excess pressure relief valve is provided for the hydraulic cylinders 30, 41 and means are included for replenishing the fluid therein. After extrusion the mandrel and pressing stem are retracted by return piston-rods 50 and the discard is severed by a saw. The die assembly is then replaced.