A High-Efficiency Impeller Channel Quasi-Triangular Tool Path Planning Method Based on Template Trajectory Mapping

基于模板轨迹映射的叶轮流道拟三角型高效路径规划方法

Received: 16 January 2018

Abstract

The manufacturing technology of an integral impeller is an important indicator for measuring the manufacturing capability of a country. Its manufacturing process involves complex free-form surface machining, a time consuming and error-prone process, and the tool path planning is considered as a critical issue of free-form surface machining but still lacks a systematic solution. In this paper, aiming at the tool path planning of the impeller channel, a quasi-triangular tool path planning method based on parametric domain template trajectory mapping is proposed. The main idea is to map the template trajectory to physical domain by using the mapping model of parametric domain to the physical domain to obtain the actual machining path. Firstly, the trajectory mapping model of parametric domain to physical domain is established using the morphing technique, and the template trajectory mapping method in the parametric domain is given. Secondly, the clean-up boundary of the impeller channel is determined in the parametric domain, and the quasi-triangular template trajectory of the impeller channel is defined. Finally, taking a certain type of impeller as an example, the quasi-triangular tool path of the impeller channel is calculated, and the tool path calculation time of this method is compared with that of the traditional isometric offset method. The result shows that the computational efficiency is improved by 45% with this method, which provides a new method for the rapid acquisition of NC machining tool path for impeller channels. In addition, the simulation and actual machining are carried out, the results show that the shape of actual cutting traces on the surface of the impeller channel is quasi-triangular, showing that this method is effective and feasible.

摘要

整体叶轮的制造技术是衡量一个国家制造能力的重要标志，其制造过程涉及复杂自由曲面加工，而刀具路径规划是自由曲面加工的关键问题之一。针对整体叶轮流道加工的刀具路径规划，提出一种基于参数域模板轨迹映射的拟三角型高效路径规划方法。核心思想是通过在参数域定义模板形式的加工轨迹，借助参数域到物理域的映射模型，将模板轨迹映射到物理域来计算实际加工的走刀路径。首先，利用变形映射技术，建立参数域到物理域的映射模型，并给出参数域模板形式走刀轨迹的映射方法；然后，在参数域中确定叶轮流道的清根边界，并定义叶轮流道的拟三角型模板轨迹；最后，以某叶轮为例，计算了叶轮流道加工的拟三角型刀具路径，并将该方法的刀具路径计算时间与传统的等距偏置方法进行对比，结果表明提升了45%的计算效率，为叶轮零件数控加工刀具路径的快速获取提供了一种新方法。此外，进行了仿真与实际加工验证，结果表明叶轮流道表面的实际切痕形状呈拟三角型形状，说明所提出的走刀轨迹规划方法是有效可行的。