曲面激光熔覆由于搭接率变化,易导致熔覆层厚薄不均。提出了一种自由曲面激光熔覆等搭接率熔道的轨迹生成算法。采用深度相机采集曲面的点云数据,确定一条点云束,对其拟合后作为初始熔道轨迹并根据等距离步长法得到加工点集。采用求交切片法获得垂直熔覆方向的曲面轮廓,在轮廓上搜寻加工点集的等距点。由等距点集拟合出后一道熔覆轨迹,从而保证搭接率相等。重复上述步骤直到轨迹遍历曲面。按加工点的法矢量方向确定熔覆喷头的运动姿态,使喷头轴线始终垂直加工表面。对半球形封头表面进行熔覆实验,结果表明:等间距轨迹规划算法结合喷头的变姿态适配,可获得搭接率一致的曲面熔道;得到的自由曲面激光熔覆层厚度均匀,硬度较高,无明显的道间隆起或凹陷等缺陷。

The thickness of cladding layers on free-form surface tends to be nonuniform owing to an instable overlapping ratio in the laser cladding process. In this paper, a trajectory generation algorithm for a laser cladding with an equivalent overlapping ratio on a free-form surface is proposed to solve this problem. A depth camera was used to collect the point cloud data on the whole surface. A point cloud beam was fitted as initial cladding layer, and a processing point set was obtained using the equidistant step method. The contour along the vertical direction of the cladding layer was identified by cross-section slicing, and equidistant points of processing points were fitted for ensuring the equality of the overlapping ratio. The next processing trajectory was fitted from the obtained equidistant point set until it traversed the entire surface. The posture of a cladding nozzle was determined along the normal vector direction of the processing points to keep the axis of the nozzle perpendicular to the machined surface. The results of the surface cladding experiment conducted on a hemispherical end socket reveal that cladding layer with equal overlapping ratios can be obtained by combining the equidistant trajectory algorithm and posture adaptation of the nozzle. In addition, the cladding layer on the free-form surface exhibit uniform thickness and high microhardness and have no obvious defects such as inter-channel bulging or depression.