Improvements relating to apparatus for subjecting objects to high pressures

摘要

In high pressure apparatus wherein a plurality of inwardly movable pressure-multiplying anvils (21, 22, 23, 24) are arranged around and define a space (11) for an object to be compressed, an anvil retaining structure (50) is provided having an inclined surface (51) in contact with the rear faces of all except one of said anvils, the arrangement being such that when pressure is applied to the unique anvil (21), the remaining anvils are forced inwardly to compress said object by wedge action. The numerals refer to Figs. 2 and 6 which illustrate an embodiment wherein a tetrahedral object is to be compressed. The anvils are arranged in an anvil receiving block 15 which may be made of an insulator such as methyl acrylate resin and each comprises a hard end piece 25, e.g. of tungsten carbide, of smaller cross-section than a pressure disc 27. The rear surface of the latter is machined to have a curvature corresponding to that of the area of the retaining ring surface 51 which is contacted when the object, and its enclosing pyrophillite block 11, is removed. The hard end pieces are supported by bearing rings 26 (Fig. 2, for anvil 23) and 68 (Fig. 6, for anvil 21). The anvils may be locked in position when desired by set screws 35 (Fig. 2) and 65 (Fig. 6). The assembly described is placed between bolsters 52, 60 attached between plates 54, 61 respectively of a hydraulic press and located therebetween by means of stem 40 and pins 41, 42, 43 projecting into corresponding bores in the bolsters. The upper bolster bears directly on the upper plane face of anvil 21. Friction at the surface 51 is overcome by the use of polytetrafluoroethylene sheets such as 70, 71 and by making the inclination of surface 51 slightly steeper than that of a surface perpendicular to the face of the tetrahedral pyrophillite block. Alternative lubricants are oil, graphite, molybdenum disulphide, lead or indium foil sheets coated with a lubricant, e.g. glycerine and graphite. The block 15 may be omitted if desired and replaced by nylon buttons inserted in the caps between the chamfered faces of the four anvils. Specification 847,067 is referred to.