Abstract: This manufacturing method for a link part is a method of manufacturing a link part having one end portion having a connecting hole and provided on one side in one direction from an intermediate part which is long in the one direction and has a first side wall and a second side wall each having a pilot hole at least at one end portion and disposed to face each other and a connecting wall connecting one side edge of the first side wall and one side edge of the second side wall, and the other end portion provided on the other side therefrom in the one direction. The method includes a reinforcing process of inserting a metal core into the pilot hole, and an O-bending process of O-bending the first side wall and the second side wall so that the other side edge of the first side wall and the other side edge of the second side wall are brought into contact with each other after the reinforcing process.

Abstract: There is provided a method of manufacturing a variable wall thickness steel pipe with a hollow tubular raw pipe. The method of manufacturing a variable wall thickness steel pipe includes locking the raw pipe in a die by thrusting a plug into the raw pipe from an one end side, so as to expand an outer shape on the one end side in a state, where the raw pipe is disposed inside the die and movement of the raw pipe in a longitudinal direction is restricted; and performing ironing in which an inner shape of the raw pipe is expanded while the outer shape is maintained so that a thin portion is formed by further thrusting the plug toward the other end side of the raw pipe while the locked state of the raw pipe is maintained, whereas the restriction on the raw pipe is relaxed.

Abstract: This torsion beam manufacturing method is for manufacturing a torsion beam including a central portion of which a cross-section orthogonal to a longitudinal direction is a closed cross-section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the central portion and including a closed cross-section having a shape different from the shape of the closed cross-section of the central portion. This torsion beam manufacturing method has a compression step of thickening at least the connection region through application of a compression force in the longitudinal direction to at least the connection region of a torsion beam material to obtain the torsion beam, the torsion beam material being formed with the central portion and the shape changing portion.

Abstract: This manufacturing method for a link part is a method of manufacturing a link part having one end portion having a connecting hole and provided on one side in one direction from an intermediate part which is long in the one direction and has a first side wall and a second side wall each having a pilot hole at least at one end portion and disposed to face each other and a connecting wall connecting one side edge of the first side wall and one side edge of the second side wall, and the other end portion provided on the other side therefrom in the one direction. The method includes a reinforcing process of inserting a metal core into the pilot hole, and an O-bending process of O-bending the first side wall and the second side wall so that the other side edge of the first side wall and the other side edge of the second side wall are brought into contact with each other after the reinforcing process.

Abstract: This torsion beam manufacturing method is a method for manufacturing a torsion beam which is provided with a uniformly shaped closed cross-sectional portion in which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape with a pair of ear portions, and a shape changing portion which leads to the uniformly shaped closed cross-sectional portion and in which a shape of the closed cross section changes progressively away from the uniformly shaped closed cross-sectional portion, the torsion beam manufacturing method comprising: thickening to form a pair of thickened portions in at least the shape changing portion by pressurizing each of the pair of ear portions from outside against swelling of the pair of ear portions in a slate where both outer surfaces of each of the pair of ear portions are supported.

Abstract: A method of manufacturing a flaring-processed metal pipe from a hollow shell including a plurality of portions having different deformation resistances in a circumferential direction is provided, the method includes: among the plurality of portions, specifying a portion having a relatively small deformation resistance as a low deformation resistance section, and a portion having a relatively large deformation resistance as a high deformation resistance section; and press-fitting a pipe expansion punch into the hollow shell such that a thickness reduction rate of the low deformation resistance section is smaller than a thickness reduction rate of the high deformation resistance section.

Abstract: This torsion beam manufacturing method is for manufacturing a torsion beam including a central portion of which a cross-section orthogonal to a longitudinal direction is a closed cross-section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the central portion and including a closed cross-section having a shape different from the shape of the closed cross-section of the central portion. This torsion beam manufacturing method has a compression step of thickening at least the connection region through application of a compression force in the longitudinal direction to at least the connection region of a torsion beam material to obtain the torsion beam, the torsion beam material being formed with the central portion and the shape changing portion.

Abstract: This torsion beam manufacturing method is a method of manufacturing a torsion beam that includes a uniformly shaped closed cross-sectional portion of which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the uniformly shaped closed cross-sectional portion and including a closed cross section having a shape different from the shape of the closed cross section of the uniformly shaped closed cross-sectional portion. The torsion beam manufacturing method includes pulling process of applying a tensile force in the longitudinal direction to at least the connection region of a torsion beam material including the uniformly shaped closed cross-sectional portion and the shape changing portion, to obtain the torsion beam.

Abstract: In the present invention, in a piercing punch and a burring punch which are shaft members having a first axis line as the center axis lines and are provided so as to be movable along the first axis line, first, after prepared holes having the first axis line as the center axis lines with respect to the first wall portion and the second wall portion are formed using the piercing punch, burring holes having the first axis line as the center axis lines with respect to the first wall portion and the second wall portion are formed using the burring punch.

Abstract: A metal pipe having a thickened end portion, the metal pipe includes: when viewed in a longitudinal direction of the metal pipe, a thin portion which has a thickness t0; a first thickened portion which is provided on one end and has a thickness T which is larger than the thickness t0; and a first taper portion which is provided between the thin portion and the first thickened portion and has the thickness which gradually increases from t0 to T; when a hardness of an inner surface of the first thickened portion is measured in a circumferential direction and the hardness is plotted with respect to a position in the circumferential direction, in which a waveform representing a high hardness portion having a hardness which is 95% or more of a maximum hardness in the circumferential direction and a waveform representing a low hardness portion having a hardness which is less than 95% of the maximum hardness alternately appear, and a plurality of combinations of the waveform representing the high hardness portion an

Abstract: The present invention provides a new bending apparatus and bending method of a tube material which makes it possible to achieve all of bending by a large bending radius not requiring large scale equipment or die, bending resistant to wrinkling and buckling at an inner side of the bending, and bending with a high productivity, that is, a ram bending apparatus using a punch 12 and a set of rolls 13, 13 for three-point bending of a tube material wherein the punch 12 has a groove 12a of a width of the width of a circular tube 11 or more and wherein the set of rolls 13, 13 are supported by a frame 14. The rolls 13, 13 can freely move on the frame 14 in directions away from each other in a state contacting the punch 12. The frame 14 has a hollow space 14a enabling free movement of the descending punch 12 and the circular tube 11 bent along with this during the bending of the circular tube 11.

Abstract: A coupling structure includes a hollow rod section formed of a metal pipe and fastening sections formed by plastic deformation of the metal pipe so as to be connected with end sections of the hollow rod section. The fastening section includes a pair of base end sections which are each connected with a peripheral wall section forming a closed cross-section at the end section of the hollow rod section, and are separated from each other, and a bottom wall including a flat surface connected with the pair of the base end sections, and a pair of front end sections including a pair of side walls curving inwards from at least widthwise end sections of the bottom wall on a base end section side.

Abstract: A coupling structure includes a hollow rod section formed of a metal pipe and fastening sections formed by plastic deformation of the metal pipe so as to be connected with end sections of the hollow rod section. The fastening section includes a pair of base end sections which are each connected with a peripheral wall section forming a closed cross-section at the end section of the hollow rod section, and are separated from each other, and a bottom wall including a flat surface connected with the pair of the base end sections, and a pair of front end sections including a pair of side walls curving inwards from at least widthwise end sections of the bottom wall on a base end section side.

Abstract: This torsion beam manufacturing method is a method for manufacturing a torsion beam which is provided with a uniformly shaped closed cross-sectional portion in which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape with a pair of ear portions, and a shape changing portion which leads to the uniformly shaped closed cross-sectional portion and in which a shape of the closed cross section changes progressively away from the uniformly shaped closed cross-sectional portion, the torsion beam manufacturing method comprising: thickening to form a pair of thickened portions in at least the shape changing portion by pressurizing each of the pair of ear portions from outside against swelling of the pair of ear portions in a slate where both outer surfaces of each of the pair of ear portions are supported.

Abstract: There is provided a method of manufacturing a variable wall thickness steel pipe with a hollow tubular raw pipe. The method of manufacturing a variable wall thickness steel pipe includes locking the raw pipe in a die by thrusting a plug into the raw pipe from an one end side, so as to expand an outer shape on the one end side in a state, where the raw pipe is disposed inside the die and movement of the raw pipe in a longitudinal direction is restricted; and performing ironing in which an inner shape of the raw pipe is expanded while the outer shape is maintained so that a thin portion is formed by further thrusting the plug toward the other end side of the raw pipe while the locked state of the raw pipe is maintained, whereas the restriction on the raw pipe is relaxed.

Abstract: A coupling structure includes a hollow rod section formed of a metal pipe and fastening sections formed by plastic deformation of the metal pipe so as to be connected with end sections of the hollow rod section. The fastening section includes a pair of base end sections which are each connected with a peripheral wall section forming a closed cross-section at the end section of the hollow rod section, and are separated from each other, and a bottom wall including a flat surface connected with the pair of the base end sections, and a pair of front end sections including a pair of side walls curving inwards from at least widthwise end sections of the bottom wall on a base end section side.

Abstract: This torsion beam manufacturing method is a method of manufacturing a torsion beam that includes a uniformly shaped closed cross-sectional portion of which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the uniformly shaped closed cross-sectional portion and including a closed cross section having a shape different from the shape of the closed cross section of the uniformly shaped closed cross-sectional portion. The torsion beam manufacturing method includes pulling process of applying a tensile force in the longitudinal direction to at least the connection region of a torsion beam material including the uniformly shaped closed cross-sectional portion and the shape changing portion, to obtain the torsion beam.

Abstract: A camshaft-manufacturing method includes: a split die group preparation step; a processing preparation step of preparing a cam including a through-hole, a cam body which is smaller than each of the cam accommodation portions, and ribs which are provided on both sides in a thickness direction of the cam body and configured to be fitted into the rib accommodation portions, and a hollow shaft, accommodating the cam body in the cam accommodation portion and fitting the ribs in the rib accommodation portion, and inserting the hollow shaft into the through-hole of the cam; and a processing step of performing hydroform processing, and fixing the cam to the hollow shaft by expanding the hollow shaft.

Abstract: A method for manufacturing a tubular member has: a step of disposing a steel pipe which is a material in an outer the having an inner surface having the same shape as an outer form of the tubular member with at least a part of the steel pipe being separated from the inner surface; and a step of compressing the steel pipe in the axial direction by decreasing a relative distance between a pair of pressurizing dies that respectively abut both end surfaces of the steel pipe in the axial direction in a state where a core the portion having an outer surface shape that is the same as inner surface shapes of the both end portions of the tubular member in the axial direction is inserted between the pair of pressurizing dies with at least a pan of the core the portion being separated from the inner surface of the steel pipe.

Abstract: Provided is a plastic working method of steel including austenite, the method including: analyzing a strain ratio ?x of an estimated breaking point which is specified during plastic deformation of the steel; heating a steel such that a local temperature Tlocal is within a temperature range indicated by the following expression 1, when T?x represents a strain-induced-transformation-maximum-ductility-temperature in the unit of ° C. for the strain ratio ?x, ?L?x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio ?x on a lower temperature side than T?x, ?H?x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio ?x on a higher temperature side than T?x, and Tlocal represents a local temperature in the unit of ° C. of the estimated breaking point; and plastically deforming the steel after heating: T?x?2×?L?x?Tlocal?T?x+1.25×?H?x??(Expression 1).