| 摘要 |
Disclosed is a method and an apparatus for extruding a powder material to form a pellet. The method includes the steps of: preparing a semicompacted powdered material for temporary placement in a die cavity with a constricting passage for receiving a charge of the powdered material; charging the die cavity containing the semicompacted powdered material with a predetermined amount of the powdered material; and pressing the charged powder material into the die cavity against the semicompacted material and extruding the semicompacted material from the die cavity through the constricting passage, whereby the semicompacted material is completely compressed to form a pellet, and the charged powdered material is incompletely compressed into a semicompacted form. The charging and pressing steps are repeated to successively form the powdered material into pellets via the semicompacted material. In the apparatus, a longitudinal die cavity passes through a die, and includes a first passage and a constricting passage subsequently connecting to the first passage, in which the lateral sectional dimension of the first passage is substantially uniform and the lateral sectional dimension of the constricting passage is gradually reduced. A punch is movable relative to the die in the longitudinal direction of the die cavity for slidable insertion into the die cavity, and regulated so that, when the punch is inserted into the die cavity, the punch does not substantially reach the constricting passage.
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