48 巻 (2007) 553 号 p. 135-139
The formability and the occurrence of surface cracks in the hot shear spinning of cast aluminum alloys were investigated. To eliminate their coarse microstructure and shrinkage holes, cast aluminum alloys were generally processed by hot shear spinning. The effects of ironing ratio, forming temperature, roller feed speed and tip radius on the formability and microstructure of and surface cracks in the alloys were examined. The occurrence of fractures was prevented by heating the alloys above 400 °C. The coarse microstructure of and shrinkage holes in the alloys were successfully eliminated by hot shear spinning. Surface cracks caused by a large shear deformation were reduced by decreasing roller feed speed and increasing roller tip radius. It was found that hot shear spinning is effective in improving the formability of cast aluminum alloys and the strength of the formed products.