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 V1, where the V1 is 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 Q1, where the Q1 is the high-frequency power supplied while forming the bent portion having the ratio R/W which is more than the predetermined value.

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.

A value stream process or method for forming vehicle rails from extruded aluminum tubes includes the steps of extruding an aluminum tube and hydroforming the extruded aluminum tube into a vehicle rail. More specifically, the method includes extruding the aluminum tube, bending the aluminum tube, preforming the aluminum tube, hydroforming the aluminum tube into a vehicle rail, trimming the vehicle rail to length and then artificially aging the rail followed by batch chemical pretreatment. In an alternative embodiment the artificial aging and batch chemical pretreatment processes are performed in reverse order. In either of the embodiments, localized induction annealing to recover formability may be performed between bending and preforming, between preforming and hydroforming or both.

Not only a reduction in the load resistant performance of a structural member in a vehicle body having a quenched portion with a tensile strength of 1,470 MPa or greater, but also a reduction in the shock absorbing performance associated with the HAZ softening by welding are suppressed. In a joining structure (10) for a member in a vehicle body in which a first member (11) that is made of steel, has a closed hollow cross-section having no outward flange, and is provided with a quenched portion having a tensile strength of 1,470 MPa or greater, a base material portion having a tensile strength of less than 700 MPa, and a transition portion (17) between the quenched portion (16) and the base material portion (18) in a longitudinal direction thereof, and a second member (12) that is made of steel and overlaps the first member (11) are welded to each other in an overlapping portion, the overlapping portion exists over the base material portion (18) from the quenched portion (16) of the first member (11) through the transition portion (17), and a welding portion (13) formed by welding exists in the transition portion (17) or the base material portion (18) in the first member (11).

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.

A method for warm forming an aluminum beam, such as an aluminum component for a vehicle, includes providing an extruded aluminum beam with a hollow cross-sectional shape. A portion of a forming die is heated to a desired temperature, so as to heat a portion of the aluminum beam in the die to a temperature below the artificial aging temperature of the aluminum beam. The heated aluminum beam is deformed to a desired shape with the die in a direction transverse to a length of the aluminum beam.

A method for induction bend forming of a compression-resistant pipe (1) having a large wall thickness and a large diameter, in particular, for use in power plants and pipelines, comprises: horizontal placement of the unprocessed pipe (1); feeding the pipe (1) to the passage of a front pipe section through an annular inductor (20) of an electrical induction unit; clamping the front pipe section in a bending lock (31) that is mounted on a bending arm (30), which is pivotable around a vertical axis of rotation (32) arranged laterally to the pipe; current supply to the induction unit for heating a pipe section; and deflecting the bending arm (30) by longitudinal feeding of the pipe (1) until the completion of the pipe bend (3).

The pipe (1) is compressed vertically in a pressing unit (50) prior to introduction into the inductor (20), such that a cross-section of the pipe (1) is forced into the shape of a lying oval, and a temperature profile with a lower temperature at an outer side of the bend (3.2) and with a higher temperature at an inner side of the bend (3.1) is set at least during a portion of the pipe bending process by means of a transverse movement of the inductor (20) relative to the pipe (1).

The invention relates to a method for induction bend forming a compression-resistant pipe (I) having a large wall thickness and a large diameter. According to said method, in an initial phase t1, an initial tangent (3) of the pipe (I) is heat-treated by pushing the initial tangent (3) through the inductor (20) without the intervention of the bending lock (31). At the end of the initial tangent (3) the advance of the pipe is stopped at a time t2, and the inductor (20) is moved along the pipe (I) counter to the advance direction while the bending lock (31) is closed on the pipe (I). In order to induce the bending process in a phase t3, the movement speed of the inductor (20) is reduced to zero and the latter is moved to its bending position. At the same time, the advance of the pipe (I) is started. In a phase t4, a pipe bend (4) is produced at a constant process advance speed of the pipe (I). In a phase t5, the advance speed of the pipe (I) is reduced and the inductor (20) is accelerated counter to the advance direction while the bending lock (31) is opened. In a phase t6, a final tangent (5) is heated by further advancing the inductor in the opposite direction.

Not only a reduction in the load resistant performance of a structural member in a vehicle body having a quenched portion with a tensile strength of 1,470 MPa or greater, but also a reduction in the shock absorbing performance associated with the HAZ softening by welding are suppressed. In a joining structure (10) for a member in a vehicle body in which a first member (11) that is made of steel, has a closed hollow cross-section having no outward flange, and is provided with a quenched portion having a tensile strength of 1,470 MPa or greater, a base material portion having a tensile strength of less than 700 MPa, and a transition portion (17) between the quenched portion (16) and the base material portion (18) in a longitudinal direction thereof, and a second member (12) that is made of steel and overlaps the first member (11) are welded to each other in an overlapping portion, the overlapping portion exists over the base material portion (18) from the quenched portion (16) of the first member (11) through the transition portion (17), and a welding portion (13) formed by welding exists in the transition portion (17) or the base material portion (18) in the first member (11).

An induction heating coil for stably heating a steel tube which is being fed in its axial direction without rotating, the heating being uniform in the circumferential direction and in a narrow range in the axial direction has at least two 1-turn coils in the form of a first turn coil body and a second turn coil body. The inner peripheral length Ln (the non-effective coil length) where the effective number of coil turns is less than the total number of coil turns when the coil is projected in the axial direction and the inner peripheral length L0 of the projected coil bodies (the inner coil length) satisfy Ln/L0<0.05. First and second coil bodies have insulating portions on their connecting portions, and the insulating portions are present in locations separated by a central angle of 5-45 measured from the center of the coil bodies.