| 摘要 |
PURPOSE:To extend life of a metallic die and a machine, by constituting so that pressing force of the metallic die and a punch against a body to be forged, in each up set process becomes suitable for each process, when upsetting the body to be forged by pressing force of the metallic die and the punch. CONSTITUTION:When a body to be forged is upset-worked and is forged to a prescribed shape by the first-forth processes by use of a metallic die and a punch 30, 3-port 3-position type electromagnetic changeover valves 55, 56 are provided between the first relief valve 46 and th second, third, fourth and fifth relief valves 51, 52, 53 and 54. The first changeover valve 55 freely feeds and stops pressurized oil of the relief valve 46 to the second and third relief valves 51, 52, and the second changeover valve 56 freely feeds and stops the oil to the fourth and fifth relief valves 53, 54, selectively. By operating these valves, pressing force of the metallic die and the punch against the body to be forged is controlled to force being suitable for each upset process. In this way, it is possible to obtain a forged product having no burr, etc. without flawing the metallic die and the machine, by use of a material billet whose dimension accuracy is low. |
