Abstract: In order to reduce the vibration excitation caused by the fluctuation of loaded transmission error, an optimization design of linear triangular end relief of double helical gears based on form grinding is proposed. According to the ISO definition of triangular end relief, the helix angle of starting line of modification at the tooth top and tooth root on the rotating projection plane is calculated, the modification curve is designed as linear, and the tooth surface equation of triangular end relief is determined by giving the maximum modification amount. Based on tooth contact analysis(TCA) and loaded tooth contact analysis(LTCA), the loaded transmission error of double helical gears under working load is calculated. The optimization objective was to minimize the fluctuation of the loaded transmission error, and triangular end relief parameters are optimized by genetic algorithm. The objective function is established to minimize the sum of squares of normal deviation of the modified target tooth surface. The helix angle, modulus and pressure angle are taken as design variables, and the tooth top and tooth root modification regions are approximated by genetic algorithm respectively, so as to realize the form grinding of triangular end relief. The results show that the fluctuation of loaded transmission error can be reduced to 36.65% by linear triangular end relief of double helical gears. The theoretical error of form grinding with three-section grinding wheel is controlled within 1 μm, and high accuracy is obtained. The test results of pinion for the double helical gears are controlled within grade 4 accuracy, and the contact patterns rolling test of gear pair is also performed, which verify the effectiveness of the proposed method.

Key words: double helical gears, triangular end relief, form grinding, loaded transmission error, genetic algorithm