| 摘要 |
A method and an apparatus for making a reconstituted coherent metal strand from scrap metal is disclosed, the strand being severed into suitable lengths to provide an intermediate product for subsequent processing such as into bar stock. The intermediate product has at least the outer periphery thereof fully dense so as to eliminate or minimize interior oxidation. The method comprises conversion of the scrap metal to "regularized" chips or blocks which are force-fed generally vertically downwardly through a fixed aperture to define a stream of metal pieces having a minimum density of 15-30% and which stream forms a column of said chips generally supporting itself, the stream is rapidly heated by a combination of electrical inductive energy and percolating hot gases produced by the combustion of fossil fuel (the fossil fuel is burned in a controlled manner to provide a self-generated reducing atmosphere permeating said stream). The heating is controlled to achieve a high temperature in the outer peripheral zone of the stream so as to be readily influenced by pressure to achieve welding, the core of said stream is at a lower temperature effective to permit molding but offer resistance against which the outer peripheral zone may be properly welded. The outer heated zone of the stream is subjected to relatively minimal compaction forces (800-10,000 psi) at low equivalent strain rates (operationally less than 7 sec. -1 but preferably less than 4 sec. -1) a composite strand having an impervious outer shell. A variety of starting materials may be used with this process and when selected with an appropriate combination of stream temperature, compacting pressure and time dwell during heating and compaction, a selected level of chemical or physical quality in the intermediate product may be achieved.
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