Abstract: A direct resistance heating simulation method is provided. In this method, a welding region and its peripheral region of steel sheets to be welded by a pair of electrodes are divided into a plurality of elements. A coupled analysis is performed such that a temperature, a metal structure, stress and strain at each element are determine in a mutually associated manner based on Joule loss obtained through a current analysis and a magnetic field analysis for each element. The coupled analysis is repeated to predict an effect of one or more parameters, including at least one of a frequency, a magnitude and an application time of electric current to be applied to the electrodes, a cooling time, a pressure applied from the electrodes to the steel sheets and a shape of the electrodes, on welding quality after a post-heating by direct resistance heating and to improve weld strength.

Abstract: A wire inserting device, an elongated workpiece winding apparatus having the wire inserting device, and a wire inserting method are provided to insert a wire in a bundle of an elongated workpiece at an intermediate point in the bundle. The wire inserting device includes a detector arranged at a position corresponding to the intermediate point, and a wire holder configured to releasably hold the wire. The detector is configured to move when pushed by the elongated workpiece placed at the intermediate point during a formation of the bundle of the elongated workpiece. The wire holder is configured to move in synchronization with the detector to insert the wire in the bundle at the intermediate point.

Abstract: A method and an apparatus for manufacturing a stepped member are provided. An intermediate portion of a shaft workpiece is radially enlarged while being compressed in an axial direction by applying alternating load to the intermediate portion in a direction intersecting the axial direction in a state in which pressure that compresses the shaft workpiece in the axial direction is applied to both ends of the shaft workpiece. The enlarged intermediate portion of the shaft workpiece is cat in a direction perpendicular to the axial direction so that the shaft workpiece is divided into two stepped members. Each of the stepped members has a shaft portion and a head portion provided at an axial end of the shaft portion, and the head portion has a larger diameter than the shaft portion.

Abstract: According to an embodiment, an induction heating coil includes a heating conductor portion which is formed of a conductor member and has a zigzag shape in which a bent portion opened to one side in a first direction and a bent portion opened to the other side in the first direction are alternately continuously arranged in opposite directions along a second direction crossing the first direction.

Abstract: A method for manufacturing a rack bar includes joining axial end portions of first and second bar members to each other, and forming a power transmission section on the second bar member. The first bar member has a toothed portion. When the second bar member is hollow, the method may further include thickening a wall of a portion of the second bar member along the axial direction so as to be coaxial with the first bar member. When the second bar member has a greater diameter than the first bar member, the method may further include cutting an outside diameter of a portion of the second bar member in the axial direction so as to be coaxial with the first bar member. The power transmission section is formed on the portion of the second bar member where the wall has been thickened and/or the outside diameter has been cut.

Abstract: A heating method, a heating apparatus, and a method of manufacturing a press-molded article using the heating method are provided. A pair of electrodes is arranged on a workpiece along a first direction. Each electrode has a length extending across a first heating area of the workpiece in the first direction. At least one of the electrodes is moved in the first heating area and along a second direction intersecting the first direction at a constant speed while applying electric current between the pair of electrodes to heat the first heating area by direct resistance heating. The electric current applied between the pair of electrodes is adjusted such that a heating temperature is adjusted for each segment into which the first heating area is divided so as to be side by side in the second direction.

Abstract: A heating coil is configured to inductively heat an inner surface of a tubular workpiece. The heating coil includes a head portion configured to be inserted into the workpiece and to inductively heat the inner surface of the workpiece, and a pair of lead portions connected to one end of the head portion and the other end of the head portion respectively. The head portion and the lead portions are configured as pipe members forming a series of flow channels through which coolant flows. A cross-sectional area of the flow channel inside each of the lead portion is greater than a cross-sectional area of the flow channel inside the head portion.

Abstract: A method of fabricating a rack, the method includes: supporting a first rack bar having a first toothed part on a shaft of the first rack bar; supporting a second rack bar having a second toothed part on a shaft of the second rack bar such that an axial center line of the second rack bar coincides with an axial center line of the first rack bar; supporting a joint member between the first and second rack bars such that an axial center line of the joint member coincides with the axial center lines of the first and second rack bars; rotating the joint member about the axial center lines of the first and second rack bars relative to the first and second rack bars; and bringing an end of the first rack bar and an end of the second rack bar into friction pressure welding with the joint member.

Abstract: A heating coil includes a pair of linear lead portions adapted to be connected to a power supply, and a ring-shaped or coil-shaped head portion having end portions connected to the lead portions respectively. A flow path through which a cooling medium flows is formed inside the lead portions and the head portion. An outer circumferential surface of the head portion has a circular or elliptical cross section and is configured to face a heating target portion of an inner circumferential surface of a work extending, the heating target portion extending in a circumferential direction of the work. Each of the lead portions has a straight side portion in a plane intersecting a longitudinal direction of the lead portions, the straight side portions of the lead portions being arranged in proximity to each other.

Abstract: A rack bar includes a shaft member having a toothed section. The toothed section has a plurality of rack teeth, and extends over a portion of an entire length of the shaft member along a longitudinal direction of the shaft member. The shaft member has a grinding-finished outer peripheral surface extending over the entire length of the shaft member including the toothed section. A method for manufacturing the rack bar includes forming the toothed section by plastic working and grinding the outer peripheral surface to improve shape accuracy.

Abstract: A method for manufacturing a rack bar includes joining axial end portions of first and second bar members to each other, and forming a power transmission section on the second bar member. The first bar member has a toothed portion. When the second bar member is hollow, the method may further include thickening a wall of a portion of the second bar member along the axial direction so as to be coaxial with the first bar member. When the second bar member has a greater diameter than the first bar member, the method may further include cutting an outside diameter of a portion of the second bar member in the axial direction so as to be coaxial with the first bar member. The power transmission section is formed on the portion of the second bar member where the wall has been thickened and/or the outside diameter has been cut.

Abstract: A heat treatment apparatus is configured to perform a heat treatment on a workpiece while rotating the workpiece. The heat treatment apparatus includes a rotary shaft configured to support the workpiece and on which a discharge nozzle is provided to spray cooling liquid toward the workpiece, a fixing base having a supply port and a discharge port for the cooling liquid, a coupling section coupling the fixing base and the rotary shaft to each other in a relatively rotatable manner, and a detector configured to detect a flow of the cooling liquid discharged from the discharge port. A supply passage and a discharge passage are formed inside the fixing base, the rotary shaft and the coupling section. The supply passage extends from the supply port and to the discharge nozzle. The discharge passage branches from the supply passage inside the rotary shaft and leads to the discharge port.

Abstract: Provided is a hollow rack bar including a rack portion that is engaged with a pinion gear and faces supported by a yoke. The hollow rack bar includes: the rack portion engaged with the pinion gear; and the supported faces provided on a back side of teeth of the rack portion and supported by the yoke. The rack portion is formed by locating a toothed mold on an outer face of a circular tube material, and inserting a cored bar into the circular tube material to pressurize an inner face, thereby transferring a shape of the toothed mold. The supported faces are formed by removal processing or deformation processing of a back side of the teeth rack portion of the circular tube material.

Abstract: A heating method, a heating apparatus, and a method for manufacturing a press-molded article using the heating method are provided. Electrodes are placed on a workplace to extend across a heating target region in a first direction. At least one of the electrodes is moved in a second direction perpendicular to the first direction over the heating target region while applying electric current to the electrodes. A distribution of contact pressure between at least one of the electrodes and the workpiece along the first direction is adjusted, with a plurality of segment regions being defined by dividing the heating target region such that the segment regions are arranged side by side in the first direction, and in accordance with a length of each of the segment regions between the electrodes, to adjust a healing temperature of each of the segment regions of the heating target region.

Abstract: A method for manufacturing a rack bar having a first rack and a second rack is provided. The first and second racks have an angular positional difference around an axis of the rack bar. The method includes forming a first flat surface and a second flat surface on an outer circumference of a single hollow shaft member, with the angular positional difference being provided between the first and second flat surfaces, and forming the first rack on the first flat surface and the second rack on the second rack surface by press-fitting one or more mandrels into the hollow shaft member in a state in which one or more teeth dies corresponding to the first rack and the second rack is pressed against the first flat surface and the second flat surface.

Abstract: An object of the present invention is to provide, as a simple method, a surface nitriding treatment method of a titanium material, forming a hardened nitrided layer excellent in abrasion resistance on the surface of a titanium material in a shorter time. In order to achieve the object, the present invention adopts a surface nitriding treatment method of a titanium material, wherein a hardened nitrided layer is formed on the surface of the titanium material, by blowing nitrogen gas at a flow rate of 10 L/min or more to the surface of the titanium material while the titanium material is being heated to 800° C. to 1000° C. in an inert gas atmosphere.

Abstract: A direct resistance heating method includes placing a first electrode and a second electrode such that a space is provided between the first electrode and the second electrode and such that each of the first electrode and the second electrode extends across a heating target region of a workpiece, moving at least one of the first electrode and the second electrode with an electric current being applied between the first electrode and the second electrode, and adjusting a time during which the electric current is applied for each segment region of the heating target region, the segment regions being defined by dividing the heating target region and are arranged side by side along a direction in which the at least one of the first electrode and the second electrode is moved.

Abstract: Heating coils are opposed to a portion of an annular workpiece having a continuously provided recessed surface, and the heating coils and the annular workpiece are moved relative to each other to heat the recessed surface by induction heating. The heating apparatus includes a first heating coil having a first corner conductor portion to be opposed to a first corner portion of the recessed surface and a first bottom conductor portion connected to the first corner conductor portion to be opposed to the bottom portion, and a second heating coil having a second corner conductor portion to be opposed to a second corner portion of the recessed surface and a second bottom conductor portion connected to the second corner conductor portion to be opposed to the bottom portion.

Abstract: An apparatus is provided to measure a depth of a hardened layer formed at a surface layer of a quenched workpiece. The apparatus includes an exciting coil configured to generate a magnetic flux to magnetize the workpiece and a detecting coil configured to detect the magnetic flux generated by the exciting coil. The exciting coil has a U-shaped excitation core portion and an excitation coil portion wound on the excitation core portion. The excitation core portion is arranged such that distal ends of magnetic poles of the excitation core portion face the workpiece. The detecting coil has a detection core portion and a detection coil wound on the detection core portion. The detection core portion is arranged between the magnetic poles of the excitation core portion and along a surface of the workpiece.

Abstract: Provided are a method of manufacturing a hollow rack bar including a rack portion that is engaged with a pinion gear and faces supported by a yoke easily and accurately, and the hollow rack bar. The hollow rack bar (10) includes: the rack portion (21) engaged with the pinion gear (29); and the supported faces (23) provided on a back side of teeth of the rack portion (21) and supported by the yoke (31). The rack portion (21) is formed by locating a toothed mold (39) on an outer face of a circular tube material, and inserting a cored bar (41) into the circular tube material to pressurize an inner face, thereby transferring a shape of the toothed mold (39). The supported faces (23) are formed by removal processing or deformation processing of a back side of the teeth rack portion (21) of the circular tube material.