To provide a technique capable of realizing an appropriate wear resistance in a resin coating layer. The sliding member of the present invention is a sliding member including a base layer and a resin coating layer formed on the base layer, wherein the resin coating layer is formed of a polyamide-imide resin as a binder, barium sulfate particles, molybdenum disulfide particles, and unavoidable impurities, wherein the resin coating layer is composed of a plurality of overcoated application layers, and wherein the plurality of application layers are different from each other in content of hard particles.

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.

The present invention provides a steel material which is excellent in both of the strength (particularly, fatigue strength) and the manufacturability (particularly, bending straightening properties), and thus can be used as an automobile component such as a crankshaft by being formed into a product shape, being subjected to a high strength treatment such as a nitrocarburizing treatment, and then being subjected to the bending straightening.

A non-thermal refined nitrocarburized component with excellent bending straightening and fatigue strength, includes a base metal steel material having a composition consisting of: (mass %), C: 0.35 to 0.50%; Si: 0.10 to 0.35%; Mn: 2.3 to 2.8%; S: 0.01% or less; N: 0.0030 to 0.0250%; Cu: 0 to 1.0%; Mo: 0 to 0.3%; Ni: 0 to 0.5%; Ti: 0 to 0.020%, the balance: Fe, impurities, and 3.10 £ (0.316 C+0.122).Math.(0.7 Si+1).Math.(5.1 Mn−1.12).Math.(0.364 Ni+1).Math.(2.16 Cr+1).Math.(3 Mo+1) £ 6.00. Impurities include P: 0.08% or less, Al: 0.05% or less, and Cr: less than 0.20%. In a stress concentrated region, an HV hardness 0.05 mm from a surface is 410 to 480, an HV hardness 1.0 mm from the surface is 200 or more, a compound-layer depth is 5 mm or less, and a base metal micro-structure is bainite.

A non-thermal refined nitrocarburized component with excellent bending straightening and fatigue strength, includes a base metal steel material having a composition consisting of: (mass %), C: 0.35 to 0.50%; Si: 0.10 to 0.35%; Mn: 2.3 to 2.8%; S: 0.01% or less; N: 0.0030 to 0.0250%; Cu: 0 to 1.0%; Mo: 0 to 0.3%; Ni: 0 to 0.5%; Ti: 0 to 0.020%, the balance: Fe, impurities, and 3.10 £ (0.316 C+0.122).Math.(0.7 Si+1).Math.(5.1 Mn−1.12).Math.(0.364 Ni+1).Math.(2.16 Cr+1).Math.(3 Mo+1) £ 6.00. Impurities include P: 0.08% or less, Al: 0.05% or less, and Cr: less than 0.20%. In a stress concentrated region, an HV hardness 0.05 mm from a surface is 410 to 480, an HV hardness 1.0 mm from the surface is 200 or more, a compound-layer depth is 5 mm or less, and a base metal micro-structure is bainite.

A method of manufacturing a crankshaft assembly includes configuring a crankshaft with a crankpin journal having a cavity extending at least partially from a first axial side to a second axial side of the crankpin journal, and opening at at least one of the first axial side and the second axial side. The method includes disposing a core plug in the cavity. The crankshaft has a first density and the core plug may have a second density which may be less than the first density. A crankshaft assembly includes the crankshaft and the core plug.

A method of manufacturing a crankshaft assembly includes configuring a crankshaft with a crankpin journal having a cavity extending at least partially from a first axial side to a second axial side of the crankpin journal, and opening at at least one of the first axial side and the second axial side. The method includes disposing a core plug in the cavity. The crankshaft has a first density and the core plug may have a second density which may be less than the first density. A crankshaft assembly includes the crankshaft and the core plug.

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.

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.

It is common for crankshafts of internal combustion engines to have main bearing journals provided between each of the conrod bearing journals. However, to reduce engine friction, the fewest main bearing journals that can be used while still meeting the design targets is preferred. A crankshaft for an in-line, four-cylinder engine, according to an embodiment of the disclosure, has three main bearing journals. Bridges, one each located between first and second conrod bearing journals and between third and fourth conrod bearing journals. The bridges have a cross-section with at least two concavities to improve the strength of the bridge compared to, for example, a cylindrical bridge, without greatly increasing the mass of material used in the bridge. Furthermore, a locus of a centroid of cross sections through the bridge are not coincident with an axis of rotation of the crankshaft, but instead is displaced toward the nearer conrod bearing journal.