眼镜镜片尖边轮廓的五轴数控加工

Five-axis CNC machining method for eyeglass lens edge profile

为了改善和优化眼镜镜片的加工流程,避免镜片尖边加工过程中刀轴矢量变化剧烈、影响工件表面的加工质量,提出了一种基于UG NX的五轴数控加工路径。利用智能镜框扫描仪对镜框边缘进行扫描,获得镜框凹槽点云数据文件,编写相应程序对符合眼镜片加工标准的OMA文件中的球坐标数据进行坐标及格式转换等处理。基于NURBS曲线拟合算法,实现刀路轨迹的连续性并保证拟合曲线的精度。设计和建立一种控制刀轴矢量平滑变化的刀轴驱动约束方法,依靠曲线驱动刀轴及镜片曲面法向量约束刀轴使刀头平滑进给,并将刀轨文件经过后处理转换为NC文件。最后,对加工后的镜片进行误差测量,结果表明,通过点云数据拟合刀路曲线的方法提高了加工面的精确度和光滑性,有效缩减了加工流程,提高了加工效率。

To enhance the eyeglass lens manufacturing process and mitigate issues stemming from abrupt changes in tool axis vectors during lens edge processing,which could degrade surface quality,this study introduces a five-axis numerical control machining path strategy using UG NX(Unigraphics NX).Initially,an intelligent frame scanner captures the eyeglass frame edges,generating point cloud data of the notches.A program is then crafted to convert the spherical coordinate data from OMA files,adhering to eyeglass lens processing standards,into the required coordinates and formats.Furthermore,employing the NURBS curve fitting algorithm enables continuous tool path trajectories,ensuring curve fitting accuracy.The NC(numerical control)machine tool,fitted with a specialized conical milling cutter for lens edge pro-cessing,thus improves the precision and efficiency of lens production.In addition,a technique is devel-oped to ensure the tool axis vector changes smoothly,utilizing curve-driven tool axis motion and normal vector constraints of the lens surface for steady tool feeding.The tool path file undergoes post-processing to be converted into NC code.Upon manufacturing,lens error measurement reveals that the proposed method,focusing on curve fitting and tool axis control,significantly enhances machining surface accuracy and smoothness,reduces the manufacturing timeline,and boosts machining efficiency.