When different processing methods are selected, the z-direction stress nephogram of the upper surface of straight bevel gear blank is shown in Figure 1. According to the characteristics of the initial stress inside the material before machining, the stress of the straight bevel gear blank in the Z direction before machining is 0. It can be seen from the figure that the upper surface of the straight bevel gear blank is subjected to a tensile stress of about 1.5MPa at the beginning of machining. With the continuation of machining, the tensile stress on the upper surface of the straight bevel gear blank gradually decreases, and the stress on the upper surface after machining is close to 0. After the straight bevel gear blank with two processing methods is processed, the stress distribution on the upper surface of the straight bevel gear blank is the same. The bottom of the processed tooth groove is subject to about 2MPa tensile stress, the position near the tooth top on both sides of the tooth groove is subject to about 4MPa tensile stress, the position near the tooth root is subject to about 2MPa tensile stress, and the middle part of the side is subject to about 3.5Mpa compressive stress.
When different processing methods are selected, the z-direction stress nephogram of the bottom surface of straight bevel gear blank is shown in Figure 2. It can be seen from the figure that the bottom surface of straight bevel gear blank processed in two ways is almost free of stress before processing. At the beginning of processing, the bottom surface of rear wheel blank is subject to about 1.5MPa tensile stress, and then the tensile stress on the bottom surface gradually decreases, and the stress on the bottom surface is almost zero after processing.
Cut the straight bevel gear blank along the length direction. The stress nephogram of the straight bevel gear blank section before machining is shown in Figure 3. The stress of the straight bevel gear blank section during machining is shown in Figure 4. It can be seen from the figure that the z-direction stress in the straight bevel gear blank before processing is basically 0. After different processing methods are selected, most areas of the straight bevel gear blank are internally under the action of tensile stress first. The maximum tensile stress in the processed tooth center area can reach about 4MPa, the yellow green area on the side of the tooth groove is under the compressive stress of about – 3.5Mpa, and the tensile stress at the bottom of the tooth groove is about 2MPa; When the processing continues, the range of the maximum tensile stress on the straight bevel gear blank gradually decreases. After the processing is completed, the central position of the internal material of each processed tooth is subjected to a tensile stress of about 4MPa. The orange area between the tooth top of each tooth and the lower surface of the straight bevel gear blank is subjected to a tensile stress of about 2MPa, and the yellow area inside the spur bevel gear blank is basically not subjected to stress, The left and right ends of the straight bevel gear blank are subjected to a compressive stress of about – 3.5Mpa.
After processing in mode 1, the straight bevel gear blank is cut along the width direction, and the z-direction stress nephogram of the section is shown in Figure 5. Among them, figure a shows the stress nephogram of the section of the straight bevel gear blank before machining, and figure B shows the sectional stress nephogram from the top of the tooth. It can be seen from the figure that the inner core of the straight bevel gear blank is subject to tensile stress, and most of the areas close to the surface are not subject to stress, and the red area in the figure is subject to a maximum tensile stress of about 4MPa. Figure C shows the sectional stress nephogram from the bottom of the tooth groove. The bottom of the tooth groove of the straight bevel gear blank is subjected to a tensile stress of about 2MPa, the front and rear ends of the straight bevel gear blank are displayed as a green area with a compressive stress of about -3.5mpa, and the inner core is basically not subjected to stress.
After processing in mode 2, the straight bevel gear blank is cut along the width direction, and the stress nephogram in the Y direction of the section is shown in Figure 6. Comparing Figure 6 with figure 5, the stress distribution of straight tooth section and cogging section in the two figures are basically the same.
From the above analysis, it can be concluded that the initial stress in Z direction of split straight bevel gear blank before machining is basically 0, but the stress in Z direction will be generated on the surface and inside the material of straight bevel gear blank during machining. No matter which processing method is adopted, the material inner core and surface of straight bevel gear blank will be subject to small tensile stress in the processing process. After processing, the stress on the surface of straight bevel gear blank disappears, the processed tooth inner core material is subject to small tensile stress, the middle position of the side of the tooth groove is subject to small compressive stress, and the bottom of the tooth groove is subject to tensile stress. In the whole machining process, the stress of straight bevel gear blank is relatively small.
