凹坑减阻表面拓扑磨削几何形状变异机理的研究

Study on the Variation Mechanism of Geometric Shape of Dimple Surface on Topological Grinding

为了揭示结构化凹坑减阻表面的拓扑磨削过程中,被磨削出的表面与设计表面之间的几何变异规律,通过对磨粒间相对运动状态分析,确定拓扑磨削形成凹坑长度及中间截面形状并通过仿真验证。首先,建立球冠凹坑数学模型并将中间截面拓扑变换得到磨粒簇中间截面;其次,确定影响砂轮磨粒簇长度的两个参量—砂轮基体半径、砂轮转速与工件进给速度之比,在砂轮基体半径确定的条件下,建立凹坑长度和磨粒簇长度间的精确的数学表达;最后,设计仿真实验,分别改变速比和磨削深度进行磨削得到凹坑表面,并提取中间截面数据拟合曲线与设计凹坑曲线对比。结果表明,定半径条件下满足磨粒簇长度与速比对应关系时,其形成的凹坑表面形状与设计形状相比几乎不存在变异,误差远小于其他速比所形成表面,而磨削深度略浅会使凹坑按比例缩小。

In order to reveal the geometric variation between the ground surface and the designed surface during the topological grinding process of the structural dimple drag reduction surface,the length of the dimple formed by topological grinding and the shape of the intermediate section were determined through the analysis of the relative motion state between the abrasive grains and verified by simulation.Firstly,the mathematical model of the spherical crown dimple was established and the middle section topology was transformed to obtain the intermediate section of the abrasive cluster.Secondly,the two parameters that affect the length of the grinding wheel abrasive grain cluster are determined,namely the radius of the grinding wheel matrix,the ratio of the grinding wheel speed to the workpiece feed rate,and the accurate mathematical expression between the dimple length and the abrasive grain cluster length is established under the condition that the radius of the grinding wheel matrix is determined.Finally,the simulation experiment was designed,the speed ratio and grinding depth were changed to grind to obtain the dimple surface,and the intermediate section data were extracted to fit the curve and compare with the design dimple curve.The results show that under the condition of constant radius,when the correspondence between the length of the abrasive cluster and the speed ratio is satisfied,the surface shape of the dimple formed by the abrasive cluster is almost unchanged compared with the design shape,and the error is much smaller than that of the surface formed by other speed ratios,while the grinding depth is slightly shallow will reduce the dimple proportionally.