| 摘要 |
PURPOSE:To reduce remarkably a cost for a die, by forging roughly a blank material of a specified temperature by use of a projected die and a recessed die, and thereafter, replacing only the projecting die with a finishing die, executing size-working at a normal temperature, and using a forging recessed die for a finish sizing recessed die. CONSTITUTION:A blank material is put into a recessed die 1, is forged by use of the first projecting die 2, and a rough forged part 3 is foremed. In this case, a temperature range is set to 600-800 deg.C, deformation resistance is lowered, and high carbon steel or a hard forming material can be extruded backward. Also, by use of induction heating, the blank material is subjected to surface treatment, generation of scale is prevented, also decarbonization is prevented, and abrasion of the recessed and projecting dies is reduced, by which the rough forged part 3 having uniform dimensions is obtained. Subsequently, when the forged part 3 is returned to a room temperature, it is brought to thermal contraction uniformly. It is annealed and is subjected to surface treatment, and thereafter, the forging recessed die 1 is used as it is, and the forged part 3 is put into said die. As a result, the thermal contraction quantity becomes a clearance C of cold finish sizing, the size-working is executed by ironing it by use of the second projecting die 4, and the inside face is finished precisely. |
