Patent GB-705955-A (GB)
Title: Method of and means for the removal of air from finely divided material before consolidation under pressure
IPC: B28B7/44
Filed: 1951-10-15
Abstract: 705,955. Presses for consolidating finely divided material. CLARK, F. H., and LEES, C. A. Jan. 12, 1953 [Oct. 15, 1951], No. 23930/51. Class 87 (2) Relates to the application to compression moulding machines of means for the removal of air from finely divided material before consolidation under pressure in which a hollow sealing box, slidably mounted on the ram and surrounding the die is adapted to come into sealing engagement with the mould before the mould is closed and is then connected to a source of vacuum, and comprises a press in which the sealing box is mounted on the lower end of a flanged sleeve axially slidable on the ram and a head which is axially movable with the ram relative to the sleeve against spring loading houses positively operated valves adapted to connect alternatively to atmosphere and to a source of vacuum a passage or passages in the ram leading into the space within the box around the die. The head 20, from which a skirt 21 depends and fits over the sleeve 14, is forced downwards against the pressure of springs 23 by the main press ram 25, being guided by rods 26. A chamber 28 is formed in the head 20 and can be put in communication with the atmosphere through a housing 33 and with a source of vacuum through a housing 34 and passage 37, and it is in permanent communication through a vertical passage 29 and inclined bores 30 with the inside of the sealing box 12. As the head 20 moves downwards lugs 19 thereon slide on pillars 18,-on which are the springs 23, and these pillars have cam surfaces which engage rollers 46 on the ends of horizontal tappets 45 housed in the lugs. In this way a valve 31 first closes the chamber 28 to atmosphere and a valve 32 opens it to vacuum as soon as the sealing box 12 makes airtight engagement with the upper end of the mould. The motion of the tappets 45 is communicated to the valves 31, 32 through rockers 42, and the valves are normally held closed by a common spring 39, the valve 31 being also loaded by a spring 40. On the return stroke the valve 32 is first closed and the cam surface on the other pillar opens the valve 31 to restore the interior of the sealing box 12 to atmospheric pressure. On the sides of the pillars 18 opposite the cam surfaces are flats which are engaged by rollers 47 mounted in the lugs 19 to resist side thrust. To prevent the bottom ejecting die 52 from moving upwards prematurely when suction is applied to the contents of the mould it may be mounted on a plunger 54 which has a vertical passage 58 communicating with the space below the die 52 through inclined bores 57 and with the chamber 28 through a flexible pipe 60, vacuum and atmospheric pressure thus being applied below the die in synchronism with their application to the mould. The edge of the wall of the sealing box 12 houses a sealing strip 15 which seats on the upper surface of the mould, and piston rings or packing are fitted where it is necessary to provide sealing means between moving surfaces. The stroke of the head 20 may be adjusted by nuts 24. The passages 57, 58 may be used for electrical heating wires 61. Specification 669,835 is referred to.