Patent GB-730062-A (GB)
Title: Method for the production of tubes on extrusion presses, and tube extrusion presses therefor
IPC: B21C23/21
Filed: 1952-12-23
Abstract: 730,062. Billet-piercing; extruding. SCHULER AKT.-GES., L. Dec. 23, 1952 [Dec. 24, 1951], No. 32618/52. Class 83 (4). A tube is produced in an extrusion press by first piercing a blank 25, housed in a receiver 23, by a mandrel 16 which, after passing through the extrusion die 24, then remains stationary whilst the blank is extruded by a press punch 21; the mandrel and punch are retracted together with the press ram 2 and the extruded tube is finally separated from the discard remaining in the die. The punch 21, Fig. 4, is mounted on a leading ram or crosshead 3 operatively connected through rods 5<SP>1</SP>, cross-head 37, link 36 and lever 33, 32 with a cam 31 on a crank-shaft 30. In Operation the punch is first allowed to fall until it engages the blank 25. The piercing mandrel 16, which is mounted on a piston or carrier 15 slidable in a cylinder in the press ram 2, is then pressed downwards by pressure liquid admitted from an accumulator 13 through a spring-loaded valve 19 controlled by a solenoid 42. In the accumulator 13 the liquid is stored under air pressure. During the downward movement of the piercing mandrel the press ram 2 is also moved downwards by a crank-pin 38 through a link 39. Movement of the mandrel continues until rods 20 on the piston 15 engage the top of the receiver 23. The ram 2 having then engaged the cross-head 3 moves the punch 21 to extrude the blank through the die and during this movement the liquid above the piston 15 is returned to the accumulator. The mandrel and punch are retracted together during the upward movement of the ram 2. A pair of receivers 23, 23<SP>1</SP> are mounted on a slide 44 which is movable across the press table 22 by a hydraulic piston 60 to position one of the receivers under the press whilst the other is charged with a new blank. Pressure liquid is supplied to either side of piston 60 through a valve 61 controlled automatically from the crank-shaft 30 through a gear train 74, 73, 72, 70, cam 68 and linkage 65, 62. The valve 61 may alternatively be controlled by electrical or hydraulic means operated from the crankshaft 30 or it may be moved manually by a handle 77. When the extrusion has been completed, the slide is moved and this movement causes the extruded tube to be severed from the unextruded discard remaining in the die. A piston 79 is pressed upwards by pressure liquid 80 and forms a hydraulic cushion for the extrusion die which acts thereon through a separating die 78. A safety valve 81 permits liquid to escape under excessive pressure. The solenoid 42, actuating the valve 19, is controlled by limit switches 47, 53 engaged by the slide 44; alternatively the solenoid may be controlled by manually operated switches 75, 76, or the valve 19 may be controlled mechanically. In another embodiment, Fig. 1, the cross-heed 3 is operated by a pair of hydraulic pistons 5 movable in cylinders 6 in the main ram 2. These cylinders together with the cylinder of the piston 15 operating the piercing mandrel 16 are supplied with pressure liquid from the accumulator 13 through valves 9, 19 respectively actuated by solenoids 40, 42 respectively which may be controlled automatically by the movement of the slide 44. In this embodiment the punch 21 is pressed downwards by hydraulic pressure to engage the blank 25. During the downward movement of the main ram 2, the pressure liquid above the pistons 5, 15 is forced back through the valves 9, 19 into the accumulator 13. Upon the subsequent upward movement of the main ram, the punch 21 and the mandrel 16 are retracted simultaneously with the main ram by the partial vacuum created above their respective pistons 5, 15 upon closing of the valves 9, 19.