Abstract: In a pressing step, a first forged product is pressed by a first die, and thereby, a second forged product including a rough flange having a thickness-changing portion is produced. The thickness-changing portion includes a front part protruding frontward from a side of a rough web part and a rear part protruding rearward from the side of the rough web part. Each of the front part and the rear part includes a first part, and a second part that is thicker than the first part and is located farther from the rough web part than the first part. In the pressing step, at least a part of the rough flange that is above or below the web part (thick part) is pressed by the first die, whereby the material of the first forged product in the part is caused to flow frontward and rearward, and the thickness-changing portion is formed.

Abstract: The production method disclosed is a method for producing a front axle beam. The production method includes a die forging step and a bending step. The die forging step is a step of forging a steel material with dies to produce a forged product including a rough web part, which is to be formed into a web part, and four plate-shaped rough flange parts protruding frontward and rearward from an upper side and a lower side of the rough web part, respectively. The bending step is a step of pressing at least one specified rough flange part, which is at least one of the four rough flange parts, with a first die to form a bent portion in the specified rough flange part such that the bent portion is bent inward in an up-down direction of the forged product.

Abstract: A support beam includes a first supporting portion, a second supporting portion, and an arm connecting the first supporting portion to the second supporting portion. The arm includes a web and a flange. The flange includes a first end, a second end, and a center portion. The center portion of the flange is connected to an end of the web. The flange includes bent portions at which the center line of the thickness of the flange is bent outward in the extending direction of the web in the region between the first end and the second end in a transverse cross section of the arm.

Abstract: A production method includes a forging step, a flash-trimming step, and a pressing step. In the forging step, a finish-forged product with flash is formed by an upper forging, die and a lower forging die. In the forging step, an excess portion is formed on at least one crankarm which is connected to a first or third pin, in a portion near the first or third pin, on an outer periphery of a lateral part near the upper forging die, such that the excess portion protrudes from the outer periphery. In the pressing step, the excess portion is pressed by an upper die such that the excess portion bulges toward a journal. This method allows production of a forged crankshaft with a reduced weight and a sufficient rigidity in a simple facility.

Abstract: The production method disclosed is a method for producing a front axle beam. The production method includes a die forging step and a bending step. The die forging step is a step of forging a steel material with dies to produce a forged product including a rough web part, which is to be formed into a web part, and four plate-shaped rough flange parts protruding frontward and rearward from an upper side and a lower side of the rough web part, respectively. The bending step is a step of pressing at least one specified rough flange part, which is at least one of the four rough flange parts, with a first die to form a bent portion in the specified rough flange part such that the bent portion is bent inward in an up-down direction of the forged product.

Abstract: The production method includes a first step, a second step and a third step. In the first step, a steel material is forged by dies, whereby a forged product including a rough web part and four plate-shaped rough flange parts is produced. In the second step, at least one specified rough flange part, which is at least one of the four rough flange parts, is pressed by a first die, whereby a first bent portion bending outward in an up-down direction is formed in the specified rough flange part. In the third step, the edge of the first bent portion is pressed by a second die inward in the up-down direction, whereby the edge is deformed and a second bent portion is formed. In the third step, the edge of the specified flange part is deformed while the edge is kept from deforming in a front-rear direction.

Abstract: In a pressing step, a first forged product is pressed by a first die, and thereby, a second forged product including a rough flange having a thickness-changing portion is produced. The thickness-changing portion includes a front part protruding frontward from a side of a rough web part and a rear part protruding rearward from the side of the rough web part. Each of the front part and the rear part includes a first part, and a second part that is thicker than the first part and is located farther from the rough web part than the first part. In the pressing step, at least a part of the rough flange that is above or below the web part (thick part) is pressed by the first die, whereby the material of the first forged product in the part is caused to flow frontward and rearward, and the thickness-changing portion is formed.

Abstract: A disclosed front axle beam includes a beam section. The beam section includes a first flange part, a second flange part, and a web section connecting the first flange part and the second flange part. The web section includes a varying-slope section that includes a plurality of first slope sections and a plurality of second slope sections. Each of the plurality of first slope sections inclines in one direction with respect to the vehicle-height direction in a cross section perpendicular to the longitudinal direction. Each of the plurality of second slope sections inclines in the opposite direction to the one direction with respect to the vehicle-height direction in a cross section perpendicular to the longitudinal direction. The first slope section and the second slope section are located in an alternate manner along the longitudinal direction. In this way, the rigidity of the front axle beam can be increased.

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: 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: 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: When each of the crank arms is divided by the crank arm centerline-into a right arm portion and a left arm portion, an area moment of inertia of one of the right and the left arm portions that is in a side that is subjected to the maximum load is greater than an area moment of inertia of the other arm portion that is in a side opposite to the side that is subjected to the maximum load, and, the area moment of inertia of the arm portion that is in the side opposite to the side that is subjected to the maximum load is greater than the area moment of inertia of the arm portion that is in the side that is subjected to the maximum load.

Abstract: A load due to combustion pressure is applied to each of the crank pins via a connecting rod in a direction from the axis of a piston pin to the axis of the crank pin. Each of the crank arms includes a recess in a surface adjacent to the journal, in a region inward of a peripheral region along the edge of the surface. The recess extends along the peripheral region, and is asymmetric with respect to a crank arm centerline connecting the axis of each of the crank pins to the axis of each of the journals. Each of the crank arms has a maximum flexural rigidity at a point of time when the load onto each of the crank pins due to the combustion pressure reaches a maximum. The crankshaft has a reduced weight and an increased torsional rigidity in combination with an increased flexural rigidity.

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.

Abstract: A crankshaft includes journals that define a central axis of rotation; crank pins that are eccentric with respect to the journals; crank arms connecting the journals to the crank pins; and counterweights integrated with the crank arms. Each of the crank arms has recesses in a surface adjacent to the crank pin. The recesses are disposed inward of peripheral regions in both sides along an edge of the surface, and are disposed along the peripheral regions. The crankshaft has a reduced weight, an increased torsional rigidity and an increased flexural rigidity.

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: 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: A crankshaft includes: journals that define a central axis of rotation; crank pins that are eccentric with respect to the journals; and crank arms for connecting the journals and the crank pins, wherein each of the crank arms or at least one of the crank arms integrally includes a counterweight. The crank arms have a recess in a surface adjacent to a corresponding one of the journals, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region. With this configuration, it is possible to provide a crankshaft which has reduced weight and increased torsional rigidity in combination with increased flexural rigidity.