Patent GB-537870-A (GB)
Title: Method and apparatus for making bodies of compacted powdered material
IPC: B22F3/02
Filed: 1940-01-09
Abstract: 537,870. Moulding powdered substances. WELLMAN CO., S. K. Jan. 9, 1940, No. 493. Convention date, Jan. 9, 1939. [Class 87 (ii)] A method of making a briquette composed of powdered materials which are predominantly metallic and which, when compressed to form the briquette, impart to it a tendency to expand along its major dimensions when the compacting pressure is released, comprises the steps of:- providing a mould having a peripheral cavity wall and two mutually opposite walls both of which are disposed transversely to the peripheral cavity wall and one of which is movable towards the other to exert pressure on powdered metallic material surrounded by the peripheral wall; charging the aforesaid powdered material into the mould cavity ; moving one of the opposite mould walls towards the other and thereby compacting and forming the powdered material into a coherent briquette; effecting removal of the peripheral cavity wall from restraining contact with the peripheral portions of the briquette and meanwhile clamping at least the peripheral portions of the latter between the opposite walls of the mould under a pressure sufficiently great to prevent substantial expansion of the peripheral boundary of the briquette, said clamping pressure being not less than 1,000 pounds per square inch and not more than the compacting pressure used in forming the briquette; thereafter releasing said briquette from said clamping pressure to allow it to expand, and removing it in its expanded condition from between said opposite mould walls. An apparatus for carrying out the method is shown in Figs. 1 and 2, and comprises a stationary piston 4 on which is guided the main hydraulic cylinder 5 carrying the stripping head 6 within which are positioned the hydraulically operable pistons 7, 8. A forming die comprises an outer ring 11 and a core member 13, spaced by a bottom compression ring 16. A stationary compression ram 17 is secured to the press head 2. The annular chamber 12 is filled with powdered metal mixture 14 distributed alternately between spacer rings 15, the whole being covered by a heavy compression ring 16. When fluid under pressure is admitted to the space 19, the die assembly is forced upwards, the ram 17 compressing the charge. The valve 22 is then opened to allow fluid to actuate the pistons 7, 8, and the die members 11, 13 are thus stripped from the charge, which latter is, however, still held under full compression pressure. A pin is then inserted through the holes 27, 28, 29, fluid pressure is released, and the charge lowered and removed. In the modification shown in Fig. 3, the charge is first compressed, the die 40 secured in raised position by members 38, and the cylinder 5 lowered. The stripping head 45 is then placed upon the cylinder, which is again raised, the fingers 36 stripping the die 40 while the charge is held under compression by the rubber pad 35. Figs. 7 and 8, show a further device in which, after the charge has been compressed and while it is still under compression, clamps 44 are knocked off the lugs 43a, and the die sections 41a, 42a, are knocked away from the charge.