Quenching of working surfaces of various shafts, such as straight shaft, variable diameter shaft, camshaft, crankshaft, gear shaft, machine tool lead screw, etc.; quenching of working surfaces of gears, etc.; surface quenching of workpieces such as sleeve, ring and disk, quenching of machine tool guide rail and plane, surface heat treatment of various mechanical parts such as ball head (such as various parts of automobiles and motorcycles), automatic heat treatment of steel bars and bars, and guiding workpieces such as Quenching and tempering of anchor chain, etc