| 摘要 |
781,982. Compacting powders. PRODUCTION TOOL ALLOY CO., Ltd. June 15, 1955 [June 22, 1954], No. 18307/54. Class 87(2). In a method of compacting powder by the application thereto of pressure in a closed space, a reversible lyophilic gel is interposed between the powder and the source of pressure, or between the powder and the containing walls of the closed space. The gel is such that if it is deformed under pressure it will, on release of the pressure, return to its original shape and dimensions. The object of the invention is to achieve even compacting. As shown in Fig. 1, a spherical metal ball is made from powder by the stages A ... E. In A a spherical pattern 4 is supported on a bottom plunger 2 in a die 1, and molten " Vinamold " (Registered Trade Mark-plasticized P.V.C.) is poured into the die and allowed to set to form a compressible mould 5. The flexible mould thus made is removed from the die, the pattern is withdrawn and the mould is inverted and replaced in the die (stage B). Metal powder 7 is then filled into the mould, a separately-produced " Vinamold " plug 6 (stage C) is placed on top of the powder within the mould, and a pressure of 10 tons p.s.i. is applied to the powder by means of a plunger 3 (stage D) or plunger 2 or both plungers. The mould is thereby compressed and the metal powder is compacted and made smaller in volume. The pressure is then released, a small metal ball compact remaining in the mould cavity (stage E). Fig. 2E illustrates a modification for making a cylinder 7, the cylinder being shown after it has been compacted in the space between the die 1, a " Vinamold " core 5 and a " Vinamold " cap 6. Fig. 3E illustrates another modification for making a tube 7, the tube being shown after it has been compacted between the mould 5, 6 and a steel core 9. In modifications which are not illustrated, (a) a mandrel or core may itself be made of compressed but unsintered powder not necessarily of the same composition as the powder around it, so that an article of varied composition may be produced, and (b) a cylindrical tungsten carbide body pointed at one end is made. The material placed in the mould may have been initially partly compacted. Instead of " Vinamold " the mould may be made of organo gels in general, soft vulcanized rubber or lyophilic gels such as gelatin, agar agar, egg albumin or alginic acid gels. |
