Abstract: Provided is a production method, including a first preforming process for obtaining a first preform from a billet, a second preforming process for obtaining a final preform from the first preform, and a finish forging process for forming the final preform into a finishing dimension of a forged crankshaft. In the first preforming process, a plurality of flat parts are formed by pressing pin-corresponding parts and journal-corresponding parts in a direction perpendicular to an axial direction of the billet. The second preforming process includes: a process of pressing regions to be a plurality of journals with a width direction of the flat part as a pressing direction by using a pair of first dies; and a process of, after starting pressing by the first dies, decentering regions to be a plurality of pins with the width direction of the flat part as a decentering direction by using second dies.

Abstract: An optical unit includes: a first optical device holding body that is sleeve-shaped and includes a first holding portion configured to hold therein at least one first optical device, and a first fitting portion extending from the first holding portion; a second optical device holding body that is sleeve-shaped and includes a second holding portion configured to hold therein at least one second optical device, and a second fitting portion extending from the second holding portion; and a welded portion that is melted and solidified over the first fitting portion and the second fitting portion in an overlapping portion between the first fitting portion and the second fitting portion. A first welding width at a center of the first fitting portion and a second welding width at a center of the second fitting portion are substantially identical in the optical axis direction of the optical unit.

Abstract: Provided is a production method, including a first preforming process, a second preforming process, and a finish forging process. In the first preforming process, while a plurality of flat parts are formed, a region to be a second pin is decentered. The second preforming process includes: a process of pressing each region to be a plurality of journals in a pressing direction corresponding to a width direction of the flat part by using a pair of second dies; and a process of, after starting the pressing by the second dies, decentering a region to be a first pin and to be disposed in a first position and a region to be a third pin and to be disposed in a third position from each other in opposite directions with a width direction of the flat part being as a decentering direction by using third dies.

Abstract: Disclosed is a method for producing a forged crankshaft. This production method includes: a pressing step of pressing a part in a longitudinal direction (first region) of a bar-like member with a pair of first dies, thereby decreasing a cross sectional area of the first region; and a decentering step of decentering a second region of the bar-like member with a second die with the first region being held. The second region is at least a part of the region of the bar-like member excepting the first region. The decentering direction by the second die is a direction perpendicular to each of the pressing direction by the first dies and the longitudinal direction of the bar-like member.

Abstract: Provided is a production method, including a first preforming process for obtaining a first preform from a billet, a second preforming process for obtaining a final preform from the first preform, and a finish forging process for forming the final preform into a finishing dimension of a forged crankshaft. In the first preforming process, a plurality of flat parts are formed by pressing pin-corresponding parts and journal-corresponding parts in a direction perpendicular to an axial direction of the billet. The second preforming process includes: a process of pressing regions to be a plurality of journals with a width direction of the flat part as a pressing direction by using a pair of first dies; and a process of, after starting pressing by the first dies, decentering regions to be a plurality of pins with the width direction of the flat part as a decentering direction by using second dies.

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: Provided is a production method, including a first preforming process, a second preforming process, and a finish forging process. In the first preforming process, while a plurality of flat parts are formed, a region to be a second pin is decentered. The second preforming process includes: a process of pressing each region to be a plurality of journals in a pressing direction corresponding to a width direction of the flat part by using a pair of second dies; and a process of, after starting the pressing by the second dies, decentering a region to be a first pin and to be disposed in a first position and a region to be a third pin and to be disposed in a third position from each other in opposite directions with a width direction of the flat part being as a decentering direction by using third dies.

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: A production method includes a preforming process, a forming process and a finish forging process. In the preforming process, an intermediate preform is formed from a billet. In the forming process, while each of a plurality of rough journals of the intermediate preform is held and pressed vertically by a pair of holding dies, rough pins are decentered in directions perpendicular to the pressing direction by the holding dies and an axial direction of the intermediate preform, and the intermediate preform is pressed in the axial direction of the intermediate preform. In the finish forging process, a final preform is placed such that the directions in which the rough pins are decentered are parallel to a horizontal direction, and the thus placed final preform is pressed vertically by a pair of pressing dies. The production method reduces the risk of occurrence of seams on a forged crankshaft.

Abstract: A production method includes a preforming process, a forming process and a finish forging process. In the preforming process, an intermediate preform is formed from a billet. In the forming process, while each of a plurality of rough journals of the intermediate preform is held and pressed vertically by a pair of holding dies, rough pins are decentered in directions perpendicular to the pressing direction by the holding dies and an axial direction of the intermediate preform, and the intermediate preform is pressed in the axial direction of the intermediate preform. In the finish forging process, a final preform is placed such that the directions in which the rough pins are decentered are parallel to a horizontal direction, and the thus placed final preform is pressed vertically by a pair of pressing dies. The production method reduces the risk of occurrence of seams on a forged crankshaft.

Abstract: Disclosed is a method for producing a forged crankshaft. This production method includes: a pressing step of pressing a part in a longitudinal direction (first region) of a bar-like member with a pair of first dies, thereby decreasing a cross sectional area of the first region; and a decentering step of decentering a second region of the bar-like member with a second die with the first region being held. The second region is at least a part of the region of the bar-like member excepting the first region. The decentering direction by the second die is a direction perpendicular to each of the pressing direction by the first dies and the longitudinal direction of the bar-like member.

Abstract: A method for producing a forged crankshaft includes: a clumping step of holding a first region by clumping a first region of a bar-like material by a pair of first dies, and a decentering step of decentering a second region of the bar-like material with second dies while the first region is held. The second region is a pin-corresponding part which is to be the pin. The first region is a crank arm-corresponding part which is to be the crank arm. The decentering direction by the second die is a direction perpendicular to each of the clumping direction of the first dies and the longitudinal direction of the bar-like material, and is the same direction as the decentering direction of the corresponding pin. This improves material yield while suppressing increase in the facility cost.

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: An optical unit includes: a first optical device retaining body including a first retainer, and a first fitting margin; a second optical device retaining body including a second retainer, and a second fitting margin; and a weld portion melted and solidified across the first fitting margin and the second fitting margin, the weld portion being provided in an edge surface located outside a region in an optical axis direction of the optical unit, the region being sandwiched by: a first retaining surface passing through the first retainer and perpendicular to the optical axis of the optical unit; and a second retaining surface passing through the second retainer and perpendicular to the optical axis, wherein ends of the first fitting margin and the second fitting margin in the optical axis direction in the overlapping portion are substantially aligned at the edge surface.

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: 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: An optical unit includes: a first optical device holding body that is sleeve-shaped and includes a first holding portion configured to hold therein at least one first optical device, and a first fitting portion extending from the first holding portion; a second optical device holding body that is sleeve-shaped and includes a second holding portion configured to hold therein at least one second optical device, and a second fitting portion extending from the second holding portion; and a welded portion that is melted and solidified over the first fitting portion and the second fitting portion in an overlapping portion between the first fitting portion and the second fitting portion. A first welding width at a center of the first fitting portion and a second welding width at a center of the second fitting portion are substantially identical in the optical axis direction of the optical unit.

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.