Patent GB-941621-A (GB)
Title: Four-column press
Inventor: ROSENTHAL SALI ALFRED
IPC: B21C23/21
Filed: 1960-01-15
Abstract: 941,621. Extruding; forging. LOEWY ENGINEERING CO. Ltd. April 17, 1961 [Jan. 15, 1960; March 11, 1960], Nos. 1638/60 and 8640/60. Headings B3H and B3P. [Also in Division B5] An extrusion, forging, or other press haying four tension columns connecting its two platens has these columns arranged at the corners of a parallelogram having diagonals of unequal length with the working axis of the press passing through the point of intersection of the diagonals. Fig. 4 shows the columns 13, 14, 15, 16 located at the corners of a parallelogram a, b, c, d having diagonals intersecting at e. In the embodiment of Fig. 8 one pair of columns 130, 132 is contained in a vertical plane and the other pair, 131, 133, in a horizontal plane; the diagonals in the arrangement of Fig. 4 are also mutually perpendicular. In a tube-making extrusion press the main ram 23, Fig. 3, comprises a cylindrical front portion 43 having the extrusion stem 24 rigidly secured thereto, a cross-head 44, a cylindrical intermediate portion 45 having side " windows '' 46, a cross-head 38 and a cylindrical rear portion 47 slidable in the rear platen 11. The four main hydraulic cylinders are mounted in the platen 11 in pairs of large and smaller diameter units, 25, 26 and 27, 28 respectively arranged in relation to the extrusion axis and the tension columns as shown in Fig. 7. A cylindrical mandrel 33 and its holder 34 extend rearwardly through the stem 24 and the main ram 23; its operating cylinder 35 is secured to the platen 11 by ties 62, Fig. 3. A cross-head 63 is secured to an intermediate portion of the holder 34 and extends laterally through the windows in the main ram 23 and carries hydraulic cylinders 64, 65 at its ends, the associated pistons 66, 67 being fixed to the main ram front cross-head 44. Thus, at the forward limit of movement of the mandrel holder 34 relative to the ram 23 the piston 60 of the mandrel-actuating cylinder 35 may supplement the thrust of the main cylinders on the cross-head 38; rearward movement of the mandrel and holder relative to the main ram is effected by applying pressure to pistons 66, 67. The front platen 10, mounted on a base 12 and rigidly connected to the rear platen 11 by the tension member 13, 14, 15, 16 and a bolster 19 are apertured for discharge of the tube extruded through a die 18, Fig. 4, mounted in an arm of a rotary carrier 17 which is axially movable relative to the adjacent face of the bolster 19, the carrier being gear-driven by a motor 117 on the platen 10 to bring a pair of dies successively into alignment with the bolster 19, the stem 24 and a billet container 21 being similarly carried in an arm of a rotary carrier 20, which is also motor-driven and is axially slidable towards and away from the die-carrier 17. The containers 21 are successively moved into alignment with the die opposite the bolster and into engagement therewith by a sealing head 22 supported, for sliding thereon, by the tension members 14 and 16, axial movement of the head being effected by hydraulic units 74, 77, carried by frames 75, 78 slidable on tension columns 13, 14 and 15, 16 respectively and additionally supported by the frame 12 through slideways 80, 81. The cylinders of the units 74, 77 are fixed to members 84, 86 which extend rearward through the cross-head 38 coaxially with the pistons 29, 30 of the main ram actuating units 25, 26 to form plungers operating as pistons 84, 86 within the pistons 29, 30 which are concentrically bored to provide cylinders 85, 87. Sealing of a container 20 against a die 17 is effected by feeding liquid under pressure to the cylinders 74, 77 and 85, 87, the latter being fed from a pressure accumulator (not shown). The container carrier 20 rotatably mounted on the tension column 16, comprises two arms carrying diametrically opposed containers 21. Movement of the carrier away from the die 17 is effected by two hydraulically-operated pushrods 106 carried by the front platen 10. In the embodiments disclosed the tension columns are of equal diameter but, as the pair 14, 16 are closer to the extrusion axis and take a larger proportion of the load, they may be of larger diameter than the other pair, or of higher grade material, or both. Pre-stressing of the more heavily loaded pair of columns may also be used to prevent unequal stretching of the columns. The invention is also applicable to vertical presses.