Development of induction heat treatment process for typical parts

(1) Crankshaft crankshaft heat treatment intensification technology, from nitriding intensification to induction hardening, table quenching inductor from the split crankshaft journal inductor to half ring inductor rotary quenching, to solve the problem of oil hole quenching and round corner hardening area narrow.

American Yingda company recently developed the crankshaft static quenching technology successfully, using the collector principle to achieve the shaft diameter of the static heating quenching, which is characterized by high production efficiency and low equipment cost. However, this technology is only limited to shaft diameter quenching and has not been widely used in China.

(2) Vertical shaft parts using rectangular tube heating quenching step shaft using longitudinal heating quenching method (induced current direction and inducing current in the same direction) of the stepped shaft surface quenching, artifacts become part of the sensor, the workpiece surface by high frequency current and the induced current heating at the same time, heating speed (usually only 0.5 s), since the cold hardening. A continuous surface hardening layer can be obtained on the workpiece surface at the same time. There is no overheating at the step, and the deformation is small, which greatly improves the torsional fatigue strength of the shaft. Faw, DONGqi, and so on have been used in semi – shaft production.

(3) Gear people have a long history of research and application of gear induction quenching, but the application in the automobile gear is very limited, automobile parts in the engine flying gear ring generally used induction quenching, some other transmission gear or carburizing nitriding treatment. This is because the automobile gear induction quenching process does not adopt the single tooth quenching process along the tooth groove but mainly adopts the whole heating quenching process. Germany ELDE company developed the SDF, that is, to the automobile gear at the same time double frequency profile induction quenching. This induction quenching method makes the gear have a good copy hardening layer, high fatigue strength, and reduce quenching deformation.SDF gear quenching instead of gear carburizing treatment, to improve productivity and energy saving has practical significance.

(4) Double frequency induction quenching of rolls requiring high hardness and deep hardening layer develops from single-frequency quenching to double frequency quenching. A dual-frequency sensor consists of two side-by-side sensors that supply current at different frequencies. The lower frequency is applied to the upper inductor, and the workpiece moves so that the heating depth is deeper (low frequency). At a higher frequency, the workpiece moves to a shallower heating depth, equivalent to the required thickness of the hardened layer. Compared with single frequency quenching, double frequency quenching can obtain better performance of workpiece (surface hardness, cross-section hardness gradient, hardening depth), improve work efficiency, and reduce energy consumption. In China, we can make our own dual-frequency power supply and quenching equipment. The dual-frequency quenching of rolls has been produced in many metallurgical plants. The technology of the quench spray ring has been improved and the actual effect has been achieved.

(5) Rail induction quenching USES full-length quenching to improve rail surface hardness and realize rail toughening, thus solving the deformation problem of rail heat treatment; This technology has been applied to other parts of the railway, such as a switch, wing rail, etc.

(6) Induction annealing of steel pipe weld is mainly used to eliminate welding residual stress and improve the structure so that the weld and its heat-affected area have the same structure, toughness, and strength as the base material. Domestic enterprises have been engaged in this industry, the vast majority of all equipment is domestic technology. Widely used in oil pipe, large diameter steel pipe, stainless steel pipe weld line annealing, and other high quality steel pipe manufacturing industries.

(7) The 124mm, up to 3000mm tube hole scanning quenching full set of equipment and technology has been successfully developed in China and put into production.

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