弧齿锥齿轮磨削表面烧伤建模仿真与实验验证

Modeling Simulation and Experimental Validation of Grinding Surface Burn of Spiral Bevel Gear

采用理论推导、数值仿真法和实验手段相结合的方法,首先以SG砂轮对20CrMnTi弧齿锥齿轮的成形磨削建立了温度场的有限元模型,选用了矩形分布热源的移动加载方法并用ANSYS软件进行了温度场的仿真分析,发现不同磨削参数对磨削温度场的影响规律,即随着径向进给量的增大,工件磨削区表面温度升高;砂轮速度越高,磨削温度升高;随着展成速度的增大,磨削温度呈现先减少后增加的趋势。然后观察弧齿锥齿轮大轮烧伤区的金相组织,检查齿部截面硬度梯度。发现当工件磨削表面出现轻微烧伤时,表面组织出现了屈氏体;当出现中度烧伤时,最外表面为二次淬火马氏体,下层为回火马氏体或索氏体;严重时,表面组织有索氏体。最后发现当齿轮发生轻微烧伤时,表面显微硬度明显低于磨削前的硬度,此时变质层深度大于0.2mm;严重烧伤时,表面发生了退火烧伤,表面显微硬度下降较多,变质层深度增大,且烧伤越严重,表面显微硬度下降越多。得出:当变质层深度大于0.2mm时,产生不同程度的磨削烧伤。

By using the theoretical derivation, the method of combining numerical simulation method with modern experimental means, firstly, through SG grinding wheel, the finite element model of temperature field of 20CrMnTi spiral bevel gear tooth form grinding is established, the temperature field simulation analysis is carried out by using rectangular distribution of heat source method of moving load and ANSYS software. The influence law of different grinding parameters on the distri- bution of temperature field of grinding process is got. Namely with the increase of grinding depth, the temperature of workpiece surface temperature in the grinding zone rises, grinding wheel linear velocity is higher, the grinding temperature rises. With the increment of generating speed, the graph showed a trend of increasing after the first reducing of the grinding temperature and maximum temperature are located around grinding are center. Then, the color and morphology of spiral bevel gear wheel burns surface is observed. By observing the microstructure of burn area, the organization on the surface of quenching burn area is troostite. When moderate burn of the burn area, the organization at the outer surface of the secondary quenching martensite, the bottom of quenching burn area is tempered mar- tensite or sorbite. When serious burn of the burn area, the organization at surface is sorbite. Finally, it is found that when the gear in slight burns, the surface microhardness significantly below the hard- ness before grinding, the metamorphic layer depth is greater than 0. 2 mm, when severe burns, an- nealing burn surface and surface hardness drop more, the metamorphic layer depth increased, and the more severe burns, the more fall of surface micro hardness. It is concluded that, when the metamor- phic layer depth is greater than 0. 2 mm, different degree of grinding burn is produced.