五轴数控加工3D刀具补偿及其后置处理方法
Method on five-axis CNC machine 3D cutter compensation and post-process

为解决五轴数控加工过程中，由于刀轴矢量不断变化，刀具补偿方向无法确定引起刀具在三维空间中无法补偿的问题，提出一种基于前置与后置处理的五轴数控加工3D刀具补偿方法。针对具备3D刀具补偿功能的数控系统，推导出五轴数控加工3D刀具补偿的补偿矢量与补偿后刀位点坐标的矢量计算方程，并基于前置三维软件（UG）的前置处理，建立了控制刀位文件格式的函数，实现了UG前置处理在五轴数控加工模块下输出包含切触点在内的刀位文件。根据SIEMENS 840D数控系统实现3D刀具补偿的数字控制（NC）指令格式要求，以非正交摆头转台五轴数控机床为例，通过逆向运动学变换提出具体的后置处理方法。基于智能制造软件IMSpost（后处理程序编辑器）平台和所提出的后置处理方法开发了专用后置处理器，自动获取了具有3D刀具补偿矢量信息的NC程序，基于仿真软件VERICUT平台对不同工况下整体叶轮仿真加工的结果进行对比。结果表明：当刀具因磨损发生尺寸变化时，采用提出的方法和开发的具有3D刀具补偿功能的后置处理器所获取的NC程序，可以将加工表面的欠切误差控制在0.1 mm以下，且无过切现象，有效地提高了五轴数控加工的精度和效率，避免了刀具磨损后发生刀具尺寸改变必须返回计算机辅助制造（CAM）系统重新生成刀位文件，以及再次进行后置处理的繁琐过程，验证了所提出的前置处理与后置处理方法的正确性和有效性。
In five-axis machining, as the tool axis vector changes, the tool compensation direction can not be determined resulting in the problem that the tool can not be compensated in the three-dimensional space. In order to solve this problem, a 3D tool compensation method for five-axis CNC machining was proposed based on pre-processing and post-processing. For numerical control systems with the 3D tool compensation function, the vector calculation equation about compensation vector and cutter location point coordinates after compensation in five-axis 3D tool compensation was derived. By creating the function which controls the cutter location file format in UG pre-processing, achieved that in the five-axis CNC machining module, the UG pre-processing could output the cutter location file including the contact point coordinates. According to the NC instruction format that SIEMENS 840D CNC system requests to achieve 3D cutter compensation function, a five-axis CNC machine tool with non-orthogonal table/spindle-tilting type was used as an example, and the specific post-processing method based on the inverse kinematic transformations was proposed. Based on IMSpost platform and post-processing method, a dedicated post-processor was developed. Then the NC code with 3D cutter compensation vector information could be auto-obtained. By using the VERICUT software, simulation results of integral impeller in different operating conditions were compared. The results show that when the tool size changes due to wear, adopting the proposed pre-processing method and the NC code obtained by the developed post-processor with 3D cutter compensation, the undercutting error can be controlled less than 0.1 mm without over-cutting phenomenon. It effectively improves the accuracy and efficiency of five-axis CNC machining, and avoids the complicated process that the programmer must return to CAM system to generate new tool paths and post-process cutter location data again because of tool size change due