Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Sumitomo Pipe & Tube Co., Ltd.

Hiroaki Kubota

Atsushi Tomizawa

Yuri Toda

Hiroyuki Kawata

Daisuke Maeda

Nobuhiro Okada

Masaaki Mizumura

Naoaki Shimada

Akihiro Sakamoto

Saburo Inoue

Shinjiro Kuwayama

Kazuo Uematsu

Masahiko Abe

This frame member includes a corner section extending along the longitudinal direction; a first wall section extending from an end portion of the corner section in a direction orthogonal to the longitudinal direction; and a second wall section extending from an opposite end portion of the corner section, wherein the corner section is formed with a deformation starting portion from which a deformation starts when a load is input to the frame member in the longitudinal direction, the deformation starting portion having a shape protruding to an inner bending side or an outer bending side of the corner section, and an average hardness value Hat a first region is equal to or greater than 330 Hv in Vickers hardness, and a 3-sigma range of a standard deviation σ in a frequency distribution of the hardness at the first region is equal to or greater than 60, the first region being located at a portion outwardly apart from an end portion of the deformation starting portion in the longitudinal direction by 10 mm in the longitudinal direction, at a depth of ¼ thickness of the frame member from a surface.

Frame member and vehicle body structure

This vehicle body structure includes a frame member with a first top section, a corner section, a vertical wall section, and a second top section, and a first support section and a second support section provided at the second top section. L/h≤6.7 is satisfied where the h represents a length between an outer surface of the first top section and an outer surface of the second top section, and the L represents a length between the first support section and the second support section.

Vehicle body structure

In a frame member, the hardness of a sheet-thickness-direction central section in a portion where a softening layer is provided is greater than or equal to 400 Hv, the softening layer has hardness smaller by at least 10 Hv than the hardness of the sheet-thickness-direction central section in the portion where the softening layer is provided, the thickness of the softening layer is greater than or equal to 2% of the sheet thickness but smaller than 20% of the sheet thickness, the hardness of the softening layer at the surface is greater than or equal to 0.5 times the hardness of the sheet-thickness-direction central section but smaller than 0.9 times the hardness of the sheet-thickness-direction central section, the softening layer has a first hardness changing area and a second hardness changing area, an absolute value &#x394;Hv1 of a change in hardness of the first hardness changing area in the sheet thickness direction is greater than an absolute value &#x394;Hv2 of a change in hardness of the second hardness changing area in the sheet thickness direction, and R/t&#x2264;2.5 is satisfied, where R represents the bending radius of the corner section, and t represents the sheet thickness of the corner section.

Frame member

The frame member has a flat sheet portion with a recessed portion having a pair of wall portions and a bottom portion extending between tip portions in an extending direction of the pair of wall portions, in which a Vickers hardness of a region of the flat sheet portion excluding the recessed portion is 330 Hv or more, a depth of the recessed portion is 5 mm or more, when a width of the recessed portion is Land a cross-sectional length of an inner peripheral wall of the recessed portion consisting of the pair of wall portions and the bottom portion is L, a value of (L&#x2212;L)/Lis 0.18 or more and 2.8 or less, and a Vickers hardness of a ridgeline portion extending between the flat sheet portion and the recessed portion is 1.06 times or more and 1.20 times or less the Vickers hardness of the region of the flat sheet portion excluding the recessed portion.

A heat treatment apparatus of one aspect of the present disclosure includes: a feed device that feeds a heat treatment workpiece downstream in a feed direction along a heat treatment workpiece pass-line; a heating device that includes a heating coil disposed downstream of the feed device in the feed direction and encircling the pass-line; a cooling device that is disposed adjacent to the heating coil, downstream of the heating coil in the feed direction, and encircling the pass-line; and a gas supply device that is disposed upstream of the heating coil in the feed direction, directly connected to the heating coil and encircling the pass-line, and that includes a plurality of gas compartments configured by internally partitioning the gas supply device in the feed direction.

Heat treatment apparatus, heat treatment method for steel workpiece, and hot bending method for steel workpiece

A manufacturing method for a bent member of the present invention includes a holding step of holding one end portion of a long steel material having an opening end in a longitudinal direction by a chuck, a feeding step of feeding the steel material in the longitudinal direction with the one end portion as a head after the holding step, a heating step of performing high-frequency induction heating on a portion of the steel material in the longitudinal direction to form a heated portion, a bending step of moving the chuck in a three-dimensional direction to apply a bending moment to the heated portion, and a cooling step of injecting a cooling medium to the heated portion to cool the heated portion after the bending step. When the heating step is started, the chuck is cooled by the cooling medium in a state where a heating amount applied to the one end portion when the heated portion is formed on the one end portion is greater than that of an upstream side adjacent portion adjacent to the upstream side of the one end portion as seen along a feeding direction of the steel material.

Manufacturing method for bent member and hot-bending apparatus for steel material

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 t; a first thickened portion which is provided on one end and has a thickness T which is larger than the thickness t; 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 tto 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 and the waveform representing the low hardness portion appear.

Metal pipe having thickened end portion, and method of manufacturing same

A method for manufacturing a bent member, the method includes feeding an elongated steel material in a longitudinal direction with one end portion of the steel material as a head, performing high-frequency induction heating to one portion of the steel material in the longitudinal direction by being supplied high-frequency power to form a high-temperature portion, bending the steel material by applying a bending moment in an arbitrary direction to the high-temperature portion to form a bent portion, and injecting a cooling medium to the bent portion to cool the bent portion. The bending includes forming the bent portion having a ratio R/W which is equal to or lower than a predetermined value, where the ratio R/W is a ratio obtained by dividing a bending radius R [mm] of the bent portion on a centroid line of the steel material by a dimension W [mm] in a bend direction in a cross-section of the steel material orthogonal to the centroid line, slowing down a feeding speed of the steel material less than V, where the Vis the feeding speed of the steel material while forming the bent portion having the ratio R/W which is more than the predetermined value, and reducing the high-frequency power supplied while forming the high-temperature portion less than Q, where the Qis the high-frequency power supplied while forming the bent portion having the ratio R/W which is more than the predetermined value.

Method for manufacturing bent member, and hot-bending apparatus for steel material

Provided is a high frequency induction heating apparatus capable of quenching a workpiece having an outward flange, over the whole circumference by means of a frequency with which a penetration depth of an electromagnetic wave is larger than a sheet thickness of the workpiece The high frequency induction heating apparatus includes a high frequency induction heating coil used for heating a long hollow steel workpiece having a closed cross section and an outward flange, in 3DQ in which a bending member is manufactured from the workpiece The high frequency induction heating coil includes a magnetic material core facing each other between which both faces of the outward flange are interposed, having a distance from both faces, and an induction heating coil connected to the magnetic material core and arranged surrounding an outer circumference of a general portion where the outward flange is excluded from the workpiece.

High frequency induction heating apparatus and processing apparatus

A lightweight hollow member having a high strength such as at least 780 MPa, a complicated shape which can be applied to automotive parts, a high stiffness, and excellent impact properties, and a manufacturing apparatus and method which can form the hollow member by simple steps and which use relatively small and inexpensive forming equipment are provided. The manufacturing apparatushas a feed unitwhich feeds a hollow steel material being workedhaving a closed transverse cross-sectional shape in its lengthwise direction, a support unitwhich supports the material being workedwhile it is being fed at a first position A, a heating unitwhich heats the material being workedat a second position B, a transverse cross-sectional shape modifying unitwhich carries out working to modify the transverse cross-sectional shape of the material being workedat a third position C, and a cooling unitwhich cools the material being workedat a fourth position D.

Hollow member and an apparatus and method for its manufacture

A bent member having a bent portion with an extremely small bend radius is manufactured by supporting a rectangular tube by a first support means disposed at a first position A while performing relative feeding of the rectangular tube in its lengthwise direction, locally heating the rectangular tube by a heating means disposed at a second position B, cooling the rectangular tube by a cooling means disposed at a third position C, and at the time of working, applying a shear force to the heated portion of the rectangular tube with a shear force applying meansdisposed in a downstream region D by moving the devicetwo-dimensionally or three-dimensionally simultaneously in the feed direction of the rectangular tube and in a direction generally parallel to a transverse cross section in the lengthwise direction of the rectangular tube which was heated by the heating means.

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Toyota, Japan

Hiroaki Kubota