| 摘要 |
<p>1,094,132. Extrusion presses. LOEWY ENGINEERING CO. Ltd. Feb. 23, 1965 [Feb. 27, 1964], No. 8115/64. Heading B3P. [Also in Division B5] An hydraulic press, suitable for backwardly extruding workpieces, includes platens 2 and 4 which are connected by a framework 6 and between which move independent crossheads 32 and 38. To the crosshead 32 are attached piston rods 28 and the main ram 18 of a removable tool 20. The piston rods move in fixed cylinders 22 and in cylinders 30 on the crosshead 38, bores 27 in the piston rods hydraulically interconnecting the cylinders. A workpiece B is mounted within dies 14 and 8 on the platen 2 and is adjustable horizontally and vertically by fluid pressure cylinder assemblies 56 and 58. In operation, fluid is introduced by a valve 66 to both the upper sides of pistons 24 to depress simultaneously the pistons, due to their differential area, the crossheads 32 and 38, and the tool 20. When a ring 40 co-operates with the fixed surface 43 of the die 8, the crosshead 38 halts and the crosshead 32 and tool increase in speed downwardly due to the bores 27 connecting the cylinders 22 and 30. A micro switch then opens valve 70 to introduce pressure fluid above ram 18, to commence extrusion. The space above the ram was previously filled with low pressure fluid from a reservoir 60. On completion of the operation the cylinders 16 and 22 are vented by valves 72 and 68, the residual pressure fluid in the cylinders 22 below the pistons 24 causing the crosshead 32 to rise to its original position. A stripper ring 42 prevents the extruded workpieee from sticking to the tool. The crosshead 38 is returned to its original position, and the workpiece is removed to allow the operation to be repeated.</p> |
