Patent GB-717603-A (GB)
Title: Improvements in or relating to die mechanism for extruding compressed powder rods
IPC: B22F3/20
Filed: 1952-02-07
Abstract: 717,603. Hydraulic machines. CLIMAX MOLYBDENUM CO. Feb. 7, 1952 [Feb. 23, 1951], No. 3250/52. Class 69 (2). [Also in Group V] Relates to die mechanism for extruding compressed powder rods by compressing successive increments of powder against previously formed rods by a reciprocating plunger (see Group V) and comprises a die having an elongated passage for receiving the compressed powder rod and forming a chamber to receive an added charge of loose powder, part of the die being split longitudinally to permit radial expansion, retaining means normally holding the split portion against radial expansion to clamp the compressed rod and thereby prevent movement thereof during compression of loose powder against the end of the rod and hydraulic means controlled by the axial compressive force on the rod for releasing the retaining means when the axial compressive force has reached a predetermined value to permit the radial expansion of the die and consequent movement of the compressed rod. The hydraulic operation, Fig. 9, is started by opening a valve 135, which operates pressure-regulating valves 89, 107 through part of a pilot system (shown dotted throughout) and allows hydraulic fluid to flow from two pumps 85, 86 into a conduit 95, the valve 89 being set to deliver a higher pressure than the valve 107. The ram cylinder 79 has a chamber 99 above the ram 12 and a lower chamber 124. Fluid enters a ram cylinder valve 94 which at the beginning connects the conduit 95 with a conduit 96 which leads fluid into the chamber 99 through two branches, in One of which is a restriction 98 and in the other a oneway valve 103 which closes when its arm 105 is depressed. The chamber 99 is thus supplied from two pumps and a rapid initial movement of the ram 12 results. At this point the die piston 51 is forced to hold the die segments closed by the admission of fluid to the die cylinder 49 from a third pump 87 which also .supplies hydraulic pressure to the pilot system through a pressure regulating valve 112, a further pressure reducing valve 113 being placed in the conduit to the die cylinder valve 114. The valve 114 is controlled by a valve 118, the setting of which is dependent on whether the pressure in a conduit 125 leading from the lower ram chamber 124 is more or less than the pressure in a conduit 122 leading from the upper ram chamber 99 through a relief valve 123. At the beginning of the ram stroke the valve 123 is closed and the pressure in the conduit 125 is greater, in which case the setting of the valve 118 is such that hydraulic pressure is transmitted through the pilot conduit 127 and the die cylinder valve 114 is thus set to connect the pump 87 to the cylinder 49. As the ram 12 descends the fluid supply to the chamber 99 is reduced in two stages, firstly by the operation of the pressure regulating valve 107 due to the pressure in the conduit 109 rising above the valve setting, with the result that supply from the pump 86 is cut off ; secondly by the closing of the valve 103 as the arm 105 is depressed by a cam 106 on the descending ram, with the result that hydraulic fluid can only flow to the chamber 99 through the restriction 98. As the charge of powdered metal is compressed to greater density the pressure in the chamber 99 increases, and when the required density is reached the pressure is high enough to open the relief valve 123 (which has previously been suitably set) at which the pilot conduit 122 is connected to the chamber 99 and the pressure therein exceeds that in the conduit 125, with the result that the valve 118 is operated to alter the setting of the die cylinder valve 114 so that hydraulic pressure in the cylinder 49 is relieved, so allowing the die to expand. When the ram 12 reaches the bottom of its stroke a cam 134 thereon operates a valve 121 which controls the ram cylinder valve 94, and this valve 94 is reversed so that the conduit 125 is put in communication with the conduit 95 and the conduit 96 with the tank. Thus the pressure drops in the chamber 99 and the relief valve 123 therefore closes ; the higher pressure in the conduit 125 moves back the valve 118 which in turn causes the die cylinder valve 114 to restore hydraulic pressure in the cylinder 49; the ram rises, fluid passing from the chamber 99 back to the tank, until the cam 134 moves the pilot valve 121 back to its original position and so initiates a repetition of the cycle, repetitions following automatically until the valve 135 is closed.