Abstract: A method for producing a forged crankshaft includes a die forging step, a trimming step, and an excess projecting portion bending step. The die forging step forms a finish forged blank with flash, the finish forged blank including a shape of the crankshaft, in which crank arms have excess projecting portions at outer peripheries of side portions thereof near a crank pin, the excess projecting portions projecting from the outer peripheries. The trimming step removes the flash from the finish forged blank formed in the die forging step. The excess projecting portion bending step bends the excess projecting portions of the crank arms toward a journal-side surface of the crank arm by pressing the crankshaft using a pair of first dies, the crankshaft being obtained by removing the flash in the trimming step.

Abstract: A method for producing a forged crankshaft includes a die forging step, a trimming step, and an excess projecting portion crushing step. The die forging step forms a finish forged blank with flash, the finish forged blank including a shape of the crankshaft, in which crank arms have excess projecting portions at outer peripheries of side portions thereof near a crank pin, the excess projecting portions projecting from the outer peripheries. The trimming step removes the flash from the finish forged blank formed in the die forging step. The excess projecting portion crushing step crushes the excess projecting portions of the crank arms by pressing the crankshaft using a pair of first dies, the crankshaft being obtained by removing the flash in the trimming step.

Abstract: A method for producing a forged crankshaft includes a die forging step, a trimming step, and an excess projecting portion bending step. The die forging step forms a finish forged blank with flash, the finish forged blank including a shape of the crankshaft, in which crank arms have excess projecting portions at outer peripheries of side portions thereof near a crank pin, the excess projecting portions projecting from the outer peripheries. The trimming step removes the flash from the finish forged blank formed in the die forging step. The excess projecting portion bending step bends the excess projecting portions of the crank arms toward a journal-side surface of the crank arm by inserting a first die having a U-shape from a direction of eccentricity of the crank pin to the crankshaft obtained by removing the flash in the trimming step.

Abstract: In a forming apparatus, movable journal dies and stationary journal dies retain rough journal portions of a preform blank therebetween, and reference crank pin die and movable crank pin dies contact rough crank pin portions thereof, and in this state, the movable journal dies and the movable crank pin dies are moved axially toward the reference crank pin die and the reference crank pin die and the movable crank pin dies are moved in a direction perpendicular to an axial direction. With this, weighted rough arm portions are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.

Abstract: An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

Abstract: An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

Abstract: In a forming apparatus, stationary journal dies (10U, 10B) and movable journal dies (11U, 11B) each hold and retain rough journal portions (Ja) of a preform blank (4) therebetween, and crank pin dies (12) contacts rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (11U, 11B) are moved axially toward the stationary journal dies (10U, 10B) and the crank pin dies (12) are moved in the same axial direction and in an eccentric direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the eccentric direction to increase the amount of eccentricity to that of the crank pins of the forged crankshaft.

Abstract: In a forming apparatus, movable journal dies and stationary journal dies hold and retain rough journal portions of a preform blank therebetween, and movable crank pin dies contact rough crank pin portions thereof, and in this state, the movable journal dies and the movable crank pin dies are moved axially toward the stationary journal dies and the movable crank pin dies are moved in a direction perpendicular to an axial direction. With this, rough arm portions are axially compressed to reduce their thickness to that of arms of a forged crankshaft, and the rough crank pin portions are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.

Abstract: A forged crankshaft manufacturing apparatus processes a forged blank with no flash. The forged blank includes at least one rough crank arm having an excess portion protruding from an outer periphery of a side portion thereof. The manufacturing apparatus includes a first die and a second die paired with each other, a retaining device, and a moving device. The first die and the second die bend or crash the excess portion. The retaining device retains at least one of the rough journals or at least one of the rough pins such that a rough pin decentering direction is perpendicular to a reducing direction in which the first die and the second die apply force for reduction. The moving device supports the retaining device such that the retaining device is movable in the reducing direction.

Abstract: A crankshaft includes journals serving as a central axis of rotation, crank pins decentered from the journals, and crank arms connecting the journals and the crank pins. Some or all of the crank arms have counterweights integrated therewith. At least one of the crank arms has a recess in a crank pin facing surface. The crank arm includes ribs formed respectively in two side portions of the recess along a periphery of the crank arm.

Abstract: An apparatus for manufacturing a forged crankshaft includes a pair of upper and lower dies and a first tool. The pair of dies deforms first excess portions and thereby thickens both side portions of a rough crank arm, in a region near a rough pin adjacent thereto. The first tool is fitted in an open space made in the pair of dies, and is capable of coming into contact with a rough-journal-facing surface of the rough crank arm, except the side portions in the region near the adjacent rough pin. The first pair of dies and the first tool have first guides to guide the first tool from a retracting position to a contacting position. The first guides include a first guide disposed on at least one of an upper surface and a lower surface of the first tool.

Abstract: An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

Abstract: The disclosed production method includes a rough forging step of performing die forging to obtain a rough forged blank with flash having a crankshaft shape, and a finish forging step of applying die forging by use of a first pair of dies to the rough forged blank to obtain a finish forged blank with flash. In the rough forged blank, at least one of the rough crank arms have, in a region near an adjacent rough pin, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm. During the die forging in the finish forging step, the first excess portion is deformed by the first pair of dies to bulge toward an adjacent rough journal.

Abstract: An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

Abstract: A method for producing a forged crankshaft includes a die forging step of forming a forged blank having a crankshaft shape by die forging, and a pressing step of pressing the forged blank by a first dies. The forged blank includes first excess portions attached to some or all of crank arms each incorporating a counterweight, each of the first excess portions protrudes from a side portion of the crank arm, in a region near a journal. In the pressing step, the first excess portions are deformed by the first dies such that each of the first excess portions bulges toward a pin. This facilitates the production of a forged crankshaft with a reduced weight and assured stiffness.

Abstract: A forged crankshaft production method includes a first preforming step, a second preforming step, and a final preforming step. The first pair of dies includes web processing parts to come into contact with portions to be formed into arms and portions to be formed into weights integrated with the arms. Each of the web processing parts includes an arm processing part and a weight processing part. The arm processing part and the weight processing part form a recessed portion, and the width of the open side of the weight processing part becomes greater with increasing distance from the bottom of the recessed portion. Accordingly, in the blank, volume can be distributed between a portion to be formed into an arm and a portion to be formed into a weight integrated with the arm, and the material yield rate can be improved.

Abstract: A forged crankshaft production method includes a first preforming step, a second preforming step, and a final preforming step. In the first preforming step, sectional areas of portions to be formed into pins and sectional areas of portions to be formed into journals are decreased, whereby flat portions are formed, and the portion to be formed into the pin located at a second position is decentered. In the second preforming step, a portion to be formed into the pin located at a first position is decentered, and a portion to be formed into the pin located at a third position is decentered to a side opposite to the portion to be formed into the pin located at the first position. In a blank obtained thereby, portions to be formed into pins have been reduced and decentered, and the material yield rate can be improved.

Abstract: The disclosed production method includes a die forging step of obtaining a forged blank with flash having a crankshaft shape, and a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies. In the forged blank, at least one of the rough crank arms have, in a region near an adjacent rough pin, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm. When the forged blank is nipped with the pair of holding dies, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent rough journal.

Abstract: In a forming apparatus, journal dies hold and retain rough journal portions of a preform blank therebetween, and reference crank pin die and movable crank pin dies contact rough crank pin portions thereof. In this state, the journal dies and the movable crank pin dies are moved axially toward the reference crank pin die and the reference crank pin die and the movable crank pin dies are moved perpendicular to an axial direction. With this, rough crank arm portions are axially compressed to reduce their thickness to that of crank arms of a forged crankshaft, and the rough crank pin portions are pressed perpendicular to the axial direction to increase an amount of eccentricity to that of the forged crankshaft crank pins. Consequently, it is possible to form a blank for finish forging having a shape generally in agreement with a shape of the forged crankshaft for a three-cylinder engine.

Abstract: A method for producing a forged crankshaft includes: a preforming step of forming a preformed blank with no flash, the preformed blank including a shape of the crankshaft, wherein the crank arm have excess projecting portions at an outer peripheries of side portions of the crank arm near the crank pin; a die forging step of forming a forged blank with flash by pressing the preformed blank with a pair of first dies; and a trimming step of removing the flash from the forged blank. In the die forging step, while a second die is abutted against a journal-side surface of the crank arm and holds the surface, the excess projecting portions of the crank arm are deformed by the first dies so as to increase the side portions of the crank arm in thickness.