GB919520A - Improvements in hydraulic metal-tube extrusion presses - Google Patents

Abstract

919,520. Extruding. SCHLOEMANN A.G. Oct. 28, 1960 [Nov. 16, 1959], No. 37080/60. Class 83 (4). An hydraulically-operated metal tube extrusion press has a billet-piercing mandrel 11 passing through the press ram 5 and actuated hydraulically in both directions, and a throttle valve D is provided in the exhaust pipe 28, 27, 32 of the mandrel retraction cylinder 13 to restrict the independent forward movement of the mandrel during the actual extrusion. The press ram 5 is carried by a platen 6 guided on the press columns 10 or on a bottom track and actuated by a hollow main piston 7 in a stationary hydraulic cylinder 8 supplied through pipe 20. Mandrel 11 is secured to a cross-head 12 actuated in the forward direction by a piston 15 working in a cylinder 16 formed in the main piston 7. Cylinder 16 is supplied with highpressure liquid, for piercing purposes, through pipes 21, 22, 23, valve LE and pipe 24 or with low-pressure liquid through valve LA from an air-loaded reservoir 25 charged by a pump 26 and fitted with an overflow 40. Mandrel crosshead 12 has a pair of retraction cylinders 13 joined by duct 30 and working over pistons 14 mounted in the platen 6. These cylinders 13 are connected by flexible pipe 28 or alternatively by telescopic tubes, and pipe 27, with a pressure inlet valve RE, or an exhaust valve RA, or a manually-operated throttle valve DV in series with a manually or automatically adjustable throttle member D in an exhaust pipe 32. In operation, a billet is charged into container 4, pressure liquid is supplied to cylinder 8 for advancing the ram 5, and valve LE is then opened for high-pressure liquid to enter cylinder 16 and press the piercing mandrel 11 through the billet. The piercing movement is terminated by cross-head 12 engaging a contact 35 which closes valves LE and RA and opens valves LA and DV whereby the ram 5 then advances to extrude the billet between die 3 and mandrel 11, low-pressure liquid being supplied to the mandrel cylinder 16 and the advance of the mandrel being restricted by throttling the exhaust from cylinders 13. When the platen 6 engages a limit switch or succession of switches 38, the throttling member D is adjusted automatically to widen the throttle. A pump may be used instead of the reservoir 25. Specification 131,181 is referred to.