To manufacture a high strength, high hardness aluminum or its alloy easily without using an expensive drawing die by applying a twisting processing to an aluminum or aluminum alloy bar in one direction and after then twisting it back to a reverse direction.
An aluminum or aluminum alloy bar is prepared as a raw material. This bar may be an extrusion bar, a continuous cast rolling bar, a drawing bar and, also, any one thereof for which annealing or stability treat heating is applied. As an aluminum, an industrial pure aluminum, for example, 1060, 1050 and the like may be used. When a higher strength is required, it is preferable that an Al-Mg system alloy is selected out of the aluminum alloy. For these bars, a twisting processing is applied first in one direction. Then, the same number of twisting back is applied in a reverse direction. Thus, the status of a surface roughness and a metal flow are restored to almost the same level as before the twisting in a manner that it becomes hardly distinguishable from appearance.
SAJI SHIGEOKI
TANAKA IWAO
FURUKAWA ELECTRIC CO LTD
WASHIN KOGYO CO LTD
TOYAMA SUMITOMO DENKO KK