After optimizing the process, the effective hardened layer depth of the tooth root is 1.4mm, as shown in Figure 1. The optimized and improved gear hub successfully passed the 1200 hour bench durability life test.
1) Optimization and improvement of drawings: technical requirements are added, and the hardened layer depth of tooth root shall not be less than 0.7mm. Specify the heat treatment requirements for the spline root to ensure that the heat treatment process can meet the design requirements.
2) Optimization and improvement of heat treatment process: change to medium frequency induction heating equipment to increase the induction ring to the spline root, ensure that the hardness of the inner spline core is 45hrc and the surface hardness is 48 ~ 56hrc, and ensure that there is a deep 0.7mmm min hardening layer at the spline root.
It can be seen from the two figures in Figure 2 that the overall appearance and spline of the gear hub are normal, and the flaw detection spline and spline root are normal. Therefore, the optimization of the heat treatment process of the gear hub enhances the hardness of the spline root, improves the durability and service life of the whole part, so as to achieve the design service life value, and effectively solves the fault problem of the central transmission of the bulldozer. At present, the improved parts have been applied to the whole machine for more than 7000 hours without fault feedback.