Local induction heating process of large spur gear

Gear is one of the most widely used parts in mechanical transmission. Its quality and service life directly affect the operation of the whole equipment. With the development of economic construction, the demand for large heavy-duty gears is increasing. Improving the quality and service life of spur gears can make the heavy machinery industry obtain great economic benefits. One of the failure forms of spur gears is tooth breakage caused by bending stress, and the other is tooth surface fatigue pitting, peeling, plastic deformation and wear caused by contact stress. Moreover, a large number of failures of large spur gears are tooth surface damage under the action of contact stress. The service life of spur gears is lower when the geometric meshing relationship is damaged due to the wear of working surface. The heat treatment of spur gear is an important process of spur gear machining. Among them, the local induction heating strengthening of large spur gear can strengthen the parts that are easy to fail.

In order to improve the quality of induction heating treatment, many scholars at home and abroad have carried out finite element simulation analysis of induction heating process. Zhang Xuebiao and Zhang Jixiang established a multi field coupled finite element model of workpiece moving induction heating process, and obtained the distribution law of temperature field and stress field under the influence of end effect in the heating process of steel plate. Gao et al. Studied the influence of the size of the guide magnet on the local induction heating process through numerical simulation and experimental verification, and found the influence law of the size of the guide magnet which can obtain the best heating rate and the size of the guide magnet on the temperature uniformity; Huy Tien et al. Conducted finite element simulation and experimental verification on the induction heating process of induction coil with guide magnet of injection mold. It was found that the temperature uniformity of the inner surface of the workpiece was the highest when the distance between guide magnets was 8mm. The progress of induction heating heat treatment technology promotes its application in the induction heat treatment process of large transmission parts such as large spur gear, rack and ring gear. Many scholars have simulated the heat treatment process, Du Guojun and others have simulated the quenching process of carburized spur gear, and obtained the distribution law of quenching temperature field and residual stress field under different carburized layer thickness, which provides a guiding basis for the actual quenching process. Song Sheng and others simulated three different quenching processes of large rack, obtained the distribution of temperature field and residual stress field, and compared with the test, found that gas quenching and water quenching can effectively avoid the quenching cracking of rack, and obtained the microstructure distribution of different quenching areas of rack. Wen et al. Simulated the induction heating process of the inner gear ring of wind power generation, compared the temperature field of the inductor at different inlet positions and moving speeds, and found that the appropriate inlet position and moving speed can effectively reduce the temperature difference rate and improve the temperature uniformity.

(1) The change trend of surface and internal temperature and thermal stress of spur gear in the two schemes are obtained by ANSYS simulation. The temperature first rises sharply and then tends to be stable; The thermal stress first increases, then decreases, and finally tends to be stable; The maximum thermal stress on the tooth profile surface of the two schemes are 354.16mpa and 355.11mpa respectively, which appear at point O when heated for 0.4s.

(2) The temperature uniformity first decreased, then increased and then stabilized. The temperature uniformity of the two schemes were 92.62% and 90.28% respectively at the 5th s; The variation of thermal stress uniformity is complex, and the uniformity is better after heating for 4 s. at the 5th s, the thermal stress uniformity of the two schemes is 91.78% and 97.9% respectively. The changes of temperature uniformity and thermal stress uniformity are not synchronous.

The induction heating process of spur gear is simulated by using ANSYS finite element software, which not only simulates and calculates the temperature field and temperature uniformity of two different placement modes of inductors, but also simulates and calculates the thermal stress field and uniformity of spur gear, which provides a reference for the application of the new induction heating device in the local quenching strengthening of spur gear.

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