An induction hardening apparatus and methods are provided. The induction hardening apparatus includes a feed line having first and second ends. A coil assembly is positioned between the first and second ends. The feed line includes a support arrangement for supporting two workpieces against one another and transferring the workpieces simultaneously through the coil assembly along a feed axis defined by the feed line.

A method and apparatus for manufacturing a part. The part may be positioned in a chamber. The part may be comprised of a metal and may be a positioned part. A gas containing nitrogen may be sent into the chamber. An electromagnetic field may be generated in the chamber with the gas. The electromagnetic field may heat a portion of the metal in the positioned part to a temperature from about 60 percent to about 99 percent of the melting point of the metal such that the portion of the metal has a desired hardness. The portion of the metal may extend from a surface of the positioned part to a selected depth from the surface.

A method and apparatus for manufacturing a part. The part may be positioned in a chamber. The part may be comprised of a metal and may be a positioned part. A gas containing nitrogen may be sent into the chamber. An electromagnetic field may be generated in the chamber with the gas. The electromagnetic field may heat a portion of the metal in the positioned part to a temperature from about 60 percent to about 99 percent of the melting point of the metal such that the portion of the metal has a desired hardness. The portion of the metal may extend from a surface of the positioned part to a selected depth from the surface.

The present invention is steel for surface hardening for machine structural use which contains, by mass %, C: 0.3 to 0.6%, Si: 0.02 to 2.0%, Mn: 0.35 to less than 1.5%, and Al: 0.01 to 0.5%, is restricted to B: less than 0.0003%, S: 0.0001 to 0.021%, N: 0.003 to 0.0055%, P: 0.0001 to 0.03%, and O: 0.0001 to 0.0050%, has a ratio Mn/S of Mn and S satisfying 70 to 30,000, has a balance of Fe and unavoidable impurities, and, when nitrided, then induction hardened, has a surface hardenability of a Vicker's hardness when tempered at 300° C. of 650 or more.

The present invention is steel for surface hardening for machine structural use which contains, by mass %, C: 0.3 to 0.6%, Si: 0.02 to 2.0%, Mn: 0.35 to less than 1.5%, and Al: 0.01 to 0.5%, is restricted to B: less than 0.0003%, S: 0.0001 to 0.021%, N: 0.003 to 0.0055%, P: 0.0001 to 0.03%, and O: 0.0001 to 0.0050%, has a ratio Mn/S of Mn and S satisfying 70 to 30,000, has a balance of Fe and unavoidable impurities, and, when nitrided, then induction hardened, has a surface hardenability of a Vicker's hardness when tempered at 300° C. of 650 or more.

Disclosed is a heating system for molten metal handling devices, examples of which are troughs, launders and other vessels. The heating system may include a refractory containment body, heater assembly, a containment shell and a thermal inducing interface between the heater assemblies and the containment shell and/or refractory body.

Disclosed is a heating system for molten metal handling devices, examples of which are troughs, launders and other vessels. The heating system may include a refractory containment body, heater assembly, a containment shell and a thermal inducing interface between the heater assemblies and the containment shell and/or refractory body.

To reduce the roughening of a surface of a workpiece whose hardness is increased by heat treatment. In a workpiece such as a guide plate (11), not a surface (11a1) of a groove (11a) that is a desired part for hardening (hardening target position) but a surface (11a2) opposite the surface (11a1) is heat-treated as a surface to be heated that is to be directly heated by an induction heating device. This can inhibit the surface (11a1) of the hardening target position from being roughened by the heat treatment and becoming lower in surface precision than before the heat treatment. Further, according to the present invention, the use of the induction heating device makes it possible to heat-treat only a necessary part.

An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

The invention relates to a method for the induction hardening of a workpiece, in particular a toothed and/or corrugated and/or ribbed workpiece such as a gear or saw blade, wherein a matchingly shaped induction loop is guided or set over the workpiece surface to be hardened, the induction loop being formed layer-by-layer by the additive application of material, and the induction loop being shaped to match the surface to be hardened.