| dc.description.abstract | Gear system is one of most common mechanical parts for machinery, such as mechanical press machine. Wear resistance and fatigue resistance of the teeth are the most critical factors influencing gear life and can be improved using heat treatment process. To improve wear resistance, the achievement of desired hardenability is the main goal. Therefore, the steel hardening technique such as induction hardening (commonly used in gear) and quenching process takes an important role for this treatment. However, traditional physical testing for optimizing heat treatment techniques must be obtained at the expense of large amounts of labor and materials. Numerical simulation, an economic alternative technique which is based on some physical models and by combining with some numerical calculation methods can become breakthrough solution for those numerous heat treatment tests.
A numerical method is built to simulate the induction hardening-heat treatment process of the spur gear. The evolution of temperature, phase transformation, and residual stress distribution of gear tooth have been studied according to the simulation results. The hardness experimental validation is also conducted to analyze the accuracy of the numerical method. As the results, the numerical method is not too accurate in predicting the real hardness distribution due to some issues such as measurement error, parameter data mismatch between simulation and real case, and skin depth phenomenon in induction hardening which is difficult to be implemented in numerical method. Cooling time during quenching takes a big role on the distribution of martensite evolution and the hardening depth, the higher heat transfer coefficient of quenchant does not increase the maximum hardness value, but shorten the quenching time to reach it, quenching process leaves massive compressive residual stresses in the root of gear teeth and tensile residual stresses in the tip of gear teeth, design of gear influence the distortion in the gear geometry. | en_US |