Apparatus for forming a blank for finish forging for a forged crankshaft

An apparatus for forming a blank for finish forging for a forged crankshaft, the apparatus configured to form, in a process of manufacturing a forged crankshaft for a multiple cylinder engine, a blank for finish forging to be subjected to finish forging by which a final shape of the forged crankshaft is obtained,

• the apparatus configured to form the blank for finish forging from a preform blank having a crankshaft shape, the preform blank including:
• rough journal portions having an axial length equal to an axial length of journals of the forged crankshaft;
• rough crank pin portions having an axial length equal to an axial length of crank pins of the forged crankshaft and having a smaller amount of eccentricity in an eccentric direction perpendicular to the axial direction than an amount of eccentricity of the crank pins of the forged crankshaft;
• and rough crank arm portions having an axial thickness greater than an axial thickness of crank arms of the forged crankshaft,
• the apparatus, comprising:
• stationary journal dies disposed at locations corresponding to a location of one rough journal portion of the rough journal portions, the stationary journal dies configured to hold and retain the rough journal portion therebetween in the eccentric direction perpendicular to the axial direction, the stationary journal dies configured to be in contact with side surfaces of corresponding ones of the rough crank arm portions, the corresponding ones of the rough crank arm portions connecting with the rough journal portion;
• movable journal dies disposed at locations corresponding to locations of the rough journal portions excluding the rough journal portion to be held by the stationary journal dies, the movable journal dies configured to hold and retain the rough journal portions therebetween in the eccentric direction perpendicular to the axial direction, the movable journal dies configured to move axially toward the stationary journal dies while being in contact with side surfaces of corresponding ones of the rough crank arm portions, the corresponding ones of the rough crank arm portions each connecting with a corresponding one of the rough journal portions;
• and
• crank pin dies disposed at locations corresponding to locations of the rough crank pin portions, the crank pin dies configured to be brought into contact with the respective rough crank pin portions at inner sides thereof, the crank pin dies configured to move axially toward the stationary journal dies and in the eccentric direction perpendicular to the axial direction while being in contact with side surfaces of corresponding ones of the rough crank arm portions, the corresponding ones of the rough crank arm portions each connecting with a corresponding one of the rough crank pin portions,
• wherein, in a state where the rough journal portions are held and retained by the stationary journal dies and the movable journal dies and the rough crank pin portions are contacted by the crank pin dies, the movable journal dies are moved axially, and the crank pin dies are moved axially and in the eccentric direction, thereby compressing the rough crank arm portions in the axial direction so as to reduce the thickness thereof to the thickness of the crank arms of the forged crankshaft, and pressing the rough crank pin portions in the eccentric direction so as to increase the amount of eccentricity thereof to the amount of eccentricity of the crank pins of the forged crankshaft.