Abstract: The present invention relates to a mechanical part, which is obtained by: processing a steel into a shape of a part, the steel having an alloy composition containing, by weight percent, C: 0.10 to 0.30%, Si: 0.50 to 3.00%, Mn: 0.30 to 3.00%, P: 0.030% or less, S: 0.030% or less, Cu: 0.01 to 1.00%, Ni: 0.01 to 3.00%, Cr: 0.20 to 1.00%, Al: 0.20% or less, N: 0.05% or less, and the remainder of Fe and inevitable impurities, and the alloy composition satisfying the following condition: [Si %]+[Ni %]+[Cu %]?[Cr %]>0.50, in which [Si %], [Ni %], [Cu %] and [Cr %] represent the concentration of Si, the concentration of Ni, the concentration of Cu and the concentration of Cr in the alloy composition, respectively; subjecting the steel to a carburizing treatment in a vacuum, followed by gradually cooling the steel; and subsequently subjecting the steel to a high-frequency hardening to thereby harden a surface of the steel.

Abstract: A steel component formed by carburizing and then induction-hardening of a steel consisting essentially of, by mass, C: minimum 0.08% and less than 0.3%; Si: maximum 2.0%; Mn: from 0.2% to 3.0%; P: maximum 0.03%; S: from 0.005% to 0.05%; Ni: maximum 1.5%; Cr: maximum 3.0%; Mo: maximum 1.0%; O: maximum 0.0025%; and N: from 0.005% to 0.03%; and further including either or both of, by mass, Al: from 0.005% to 0.05%, and Ti: from 0.005% to 0.05%; and still further including either or both of, by mass, V: maximum 0.3%, and Nb: maximum 0.3%; and a balance including Fe and unavoidable impurities. The hardness of the surface layer is at least 55 HRC and the hardness of the core portion is from 20 to 50 HRC. The core portion does not include a martensite structure.

Abstract: The present invention provides a method for induction hardening of a steel member having an outer ring portion and, more specifically, for induction hardening of an outer circumferential surface of the outer ring portion. The method uses two pressing members, each of which includes a flat basal surface and a projecting portion projecting therefrom. Each of the projecting portions has a cross-section in the shape of a perfect circle. Also, the projecting portions have, on the outer circumferences thereof, respective pressing surfaces. While gaps are maintained between axial end faces of the outer ring portion and the basal surfaces of the pressing members, the pressing members are pressed against the outer ring portion so that the pressing surfaces each abut against the inner circumference side of the outer ring portion. While a biasing force is applied to the pressing members, the induction hardening process is applied to the outer circumferential surface.

Abstract: A method of manufacturing a sheave member for a belt-type continuously variable transmission includes a forming step wherein an intermediate product having a sheave surface is formed by forging a steel material; a carburization step wherein the intermediate product is heated in a carburization gas; a gradual cooling step wherein the cooling speed is equal to or less than 20° C./sec, at least until the temperature of the intermediate product has passed through the transformation point; a high-frequency electrical heating step wherein a selected portion(s) of the intermediate product is heated; a water quenching step wherein the selected portion is quenched by contact with water; and a finishing step wherein a grinding process is applied to the intermediate product to attain the final shape. In the cooling step, preferably, the intermediate product is contacted with a cooling gas at a pressure lower than atmospheric pressure.

Abstract: A steel component formed by carburizing and then induction-hardening of a steel consisting essentially of, by mass, C: minimum 0.08% and less than 0.3%; Si: maximum 2.0%; Mn: from 0.2% to 3.0%; P: maximum 0.03%; S: from 0.005% to 0.05%; Ni: maximum 1.5%; Cr: maximum 3.0%; Mo: maximum 1.0%; O: maximum 0.0025%; and N: from 0.005% to 0.03%; and further including either or both of, by mass, Al: from 0.005% to 0.05%, and Ti: from 0.005% to 0.05%; and still further including either or both of, by mass, V: maximum 0.3%, and Nb: maximum 0.3%; and a balance including Fe and unavoidable impurities. The hardness of the surface layer is at least 55 HRC and the hardness of the core portion is from 20 to 50 HRC. The core portion does not include a martensite structure.

Abstract: A method of carburizing and quenching a steel member includes: a reduced pressure carburization step in which a steel member is contacted with carburization gas under reduced pressure, a slow cooling step in which the steel member is then slowly cooled in a cooling gas, and a quenching step of heating a selected portion of the cooled steel member using high-density energy and subsequently subjecting the selected portion to rapid cooling. The steel member subjected to the low-pressure carburization step includes a first portion in which a diffusion rate of carbon taken therein during carburization is high because of its shape and a second portion in which the diffusion rate of carbon is lower than that of the first portion. The reduced-pressure carburization step is controlled to give a carbon concentration at the surface of the first portion in a range of 0.65±0.1 weight % after diffusion.

Abstract: The present invention provides a method for induction hardening of a steel member having an outer ring portion and, more specifically, for induction hardening of an outer circumferential surface of the outer ring portion. The method uses two pressing members, each of which includes a flat basal surface and a projecting portion projecting therefrom. Each of the projecting portions has a cross-section in the shape of a perfect circle. Also, the projecting portions have, on the outer circumferences thereof, respective pressing surfaces. While gaps are maintained between axial end faces of the outer ring portion and the basal surfaces of the pressing members, the pressing members are pressed against the outer ring portion so that the pressing surfaces each abut against the inner circumference side of the outer ring portion. While a biasing force is applied to the pressing members, the induction hardening process is applied to the outer circumferential surface.

Abstract: The present invention relates to a mechanical part, which is obtained by: processing a steel into a shape of a part, the steel having an alloy composition containing, by weight percent, C: 0.10 to 0.30%, Si: 0.50 to 3.00%, Mn: 0.30 to 3.00%, P: 0.030% or less, S: 0.030% or less, Cu: 0.01 to 1.00%, Ni: 0.01 to 3.00%, Cr: 0.20 to 1.00%, Al: 0.20% or less, N: 0.05% or less, and the remainder of Fe and inevitable impurities, and the alloy composition satisfying the following condition: [Si %]+[Ni %]+[Cu %]?[Cr %]>0.50, in which [Si %], [Ni %], [Cu %] and [Cr %] represent the concentration of Si, the concentration of Ni, the concentration of Cu and the concentration of Cr in the alloy composition, respectively; subjecting the steel to a carburizing treatment in a vacuum, followed by gradually cooling the steel; and subsequently subjecting the steel to a high-frequency hardening to thereby harden a surface of the steel.

Abstract: A method of manufacturing a sheave member for a belt-type continuously variable transmission includes a forming step wherein an intermediate product having a sheave surface is formed by forging a steel material; a carburization step wherein the intermediate product is heated in a carburization gas; a gradual cooling step wherein the cooling speed is equal to or less than 20° C./sec, at least until the temperature of the intermediate product has passed through the transformation point; a high-frequency electrical heating step wherein a selected portion(s) of the intermediate product is heated; a water quenching step wherein the selected portion is quenched by contact with water; and a finishing step wherein a grinding process is applied to the intermediate product to attain the final shape. In the cooling step, preferably, the intermediate product is contacted with a cooling gas at a pressure lower than atmospheric pressure.

Abstract: A carburizing and hardening method enhances strength while sufficiently reducing hardening strain, without increasing the production cost, and a carburized and hardened member produced thereby. The raw material is an alloy steel which contains Fe as a main component, 0.10 to 0.50 wt. % C and 0.50 to 1.50 wt. % Si and having a hardenability J, based on an end quenching test, in a range of 35 to 50 (at 12.5 mm). After the raw material is formed into the desired shape, a carburized layer is formed by carburizing in an oxidation inhibiting atmosphere. After the carburizing, quenching is performed with cooling, uninterrupted by temperature rise, from a pearlite transformation point (A1 point) to a martensite transformation start point (Ms point), and with a severity of quenching H in a range of 0.01 to 0.08 (cm?1).

Abstract: A planetary carrier supports pinion gears of a planetary gear set via pinion shafts. Each hole in which a pinion shaft is mounted has a shallow hardened wall surface that is hardened by very-high-frequency induction heating and quenching. Therefore, the durability of the pinion shaft-supporting holes of a cold-forged piece or a pressed piece can be improved without thermal strain.

Abstract: A cutting tip has a cutting face and a flank face. A compression face for plastically deforming a workpiece is provided between the cutting face and the flank face. The cutting tip allows work-hardening to be easily performed by plastic deformation of the cut-finished surface during cutting, without adding a separate process step.

Abstract: In a method for performing a finish machining on a tooth surface of a gear to be machined, in the state that at least one counter gear 2 is meshed with the gear 1 to be machined, both gears are rotated while supplying water or an aqueous solution 4 which contains no abrasive grains to meshing portions of both gears so that a surface having a small surface roughness is formed on the tooth surface of the gear 1 to be machined.

Abstract: A planetary carrier supports pinion gears of a planetary gear set via pinion shafts. Each hole in which a pinion shaft is mounted has a shallow hardened wall surface that is hardened by very-high-frequency induction heating and quenching. Therefore, the durability of the pinion shaft-supporting holes of a cold-forged piece or a pressed piece can be improved without thermal strain.

Abstract: In a steel member surface treatment method, only a surface layer portion of the steel member is heated to its melting point or higher to form a melt, by high density energy-beam irradiation. Subsequently, the melted portion is rapidly cooled to a martensitic transformation region, to form a martensitic structure. The temperature increasing rate in irradiation of the surface layer of the steel member is preferably 7500° C./second or greater. Thereby, thermal strain and quenching failure are reduced even if the steel member is a thin plate component and a high production efficiency can be achieved.

Abstract: A surface hardening method, in which a surface layer on a thin steel plate member is stably melted and solidified to provide a high surface resistance against wear includes irradiation with a high density energy beam to melt a process surface portion of the steel member followed by rapid cooling. The melted surface portion includes a fully melted layer and an adjacent imperfectly or partially melted layer. At least the cooling to solidify the molten steel is performed in a short time period less than an austenitic transformation completion time at temperatures below melting, e.g., one-twentieth of the normal austenitic transformation time, and preferably both heating to melt the surface layer and cooling to solidify and harden the surface layer are performed in a time period less than the normal austenitic transformation completion time period. The high density energy beam can be divided to irradiate plural regions to melt the surfaces of the plural regions at the same time.

Abstract: A bainite forming process for treating a steel material reduces the time required for a complete thermal treatment as well as the cycle time for the thermal treatment device without necessitating any special means for handling the steel material. The steel material is heated to a temperature higher than the austenitic transformation point, and temporarily quenched to an intermediate point temperature higher than the martensitic transformation point. Then, the temperature of the steel material is again raised towards the range corresponding to bainitic transformation to form a bainitic structure. The reheating is discontinued before the temperature corresponding to the austenitic transformation point is reached, and the steel material is then quenched. In the heating steps, only the portion to be treated by the bainite forming process is locally irradiated with a high-density energy beam.

Abstract: A lockup clutch for torque converter which prevents engaging and disengaging shock when a transmission torque suddenly changes, includes a lockup clutch assembly, a lockup clutch piston operating the lockup clutch assembly, and a damper device disposed between the lockup clutch piston and an output member for absorbing changes of transmission torque occurring in association with the operation of the lockup clutch assembly. The lockup clutch piston is made of steel and has a thermally treated portion placed at a surface in contact with springs of the damper device wherein the thermally treated portion is hardened by rapid local melting with high density energy radiation such as electron beam followed by rapid cooling.