| 摘要 |
A method for compacting articles made of powder material at a constant density, or at a density within a range. An example of apparatus for practicing the method of the invention takes the form of a hydraulic piston-cylinder assembly, defining a chamber which is filled with an uncompressible hydraulic fluid, disposed in the coupling between the actuating member of a mechanical press ram and the ram. The hydraulic fluid is pressurized by a compressed compressible fluid, such as air, acting on a large area piston directly coupled to a small area piston disposed in a small diameter cylinder filled with the uncompressible hydraulic fluid and in communication with the chamber, the ratio in the areas of the pistons determining the pressure amplification rate or gain. When the press ram meets a resistance to its travel which is large enough to overcome the pressure of the hydraulic fluid in the chamber, the volume of the chamber is decreased with the result that hydraulic fluid is introduced in the small diameter cylinder, thus displacing the small area and the large area pistons against the pressure of the compressible fluid, cushioning the impacts and shocks to which the ram is subjected in operation, and effecting compaction at constant pressure, or at a pressure within a range.
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