环形刀型面加工时行距优化及无干涉刀具轨迹规划

发布时间：2019-03-11 17:29

【摘要】：随着我国现代化制造行业的高速发展,汽车已经普遍融入到日常生活当中,汽车的销售和生产数量日益增长,因此对汽车覆盖件模具的表面质量要求越来越严格,相应的数控加工技术受到了广泛地重视。汽车覆盖件多数为自由曲面,考虑到球头刀加工自由曲面的局限性,环形刀的应用越来越广泛,但环形刀加工曲面时,时常发生干涉的现象,因此,如何规划刀具轨迹来避免干涉现象的发生,是数控编程时应主要考虑的问题。基于上述问题,本文针对两种自由曲面进行加工参数优化后,根据所得最优参数的数学模型,进行工件姿态的调整及刀具轨迹的重新规划。首先,对环形刀加工汽车覆盖件模具进行行距优化研究,分别对4种代表性型面建立了行距与刀具几何参数、残留高度之间的数学模型;针对两种常用的型面建立了基于刀位点的行距数学模型;基于所建立的数学模型,分别对4种型面进行了铣削加工实验,验证了模型的准确性。其次,针对环形刀加工凹曲面汽车覆盖件时产生的欠切干涉现象进行了研究。分析了刀触点处刀具与曲面的微分几何关系,根据所建立的行距数学模型,得出了刀轴的最优倾角;对凹曲面进行了轨迹仿真及加工效率的分析,得出了最优走刀方向后,确定了坐标系之间的转换关系,从而将工件姿态调整到最优;针对凹曲面型面,分别用传统方法和本文方法进行了对比实验,从而验证了本文方法的正确性。最后,针对环形刀加工凸曲面汽车覆盖件时产生的过切干涉现象进行了研究。通过分析干涉产生的原因,确定了消除干涉的方法;进行了凸曲面加工实验,确定干涉发生点的位置;将刀具调整到最优姿态后,应用轨迹密化法重新规划刀具轨迹,达到消除干涉的目的。针对凸曲面型面,分别用传统方法和本文方法进行了对比实验,从而验证了本文方法的可行性。
[Abstract]:With the rapid development of the modern manufacturing industry in China, the automobile has been integrated into the daily life, and the sales and production quantity of the automobile is increasing day by day. Therefore, the surface quality requirements of the automobile panel die are becoming more and more strict. The corresponding NC machining technology has been paid more and more attention. The automobile covering parts are mostly free-form surfaces. Considering the limitation of ball-head knife in machining free-form surfaces, the application of ring-shaped knives is more and more extensive. However, interference often occurs when machining surfaces with ring-shaped knives, so, How to plan tool path to avoid interference phenomenon is the main problem to be considered in NC programming. Based on the above problems, after optimizing the machining parameters of two kinds of free-form surfaces, according to the mathematical model of the optimal parameters, the adjustment of workpiece attitude and the re-planning of tool path are carried out. Firstly, the optimization of line spacing for automobile panel die with ring cutter is studied. The mathematical models of line spacing, tool geometry parameters and residual height are established respectively for four typical profile surfaces. A line spacing mathematical model based on tool point is established for two kinds of common profile surfaces, and milling experiments are carried out to verify the accuracy of the model based on the established mathematical models. Secondly, the undercutting interference caused by ring cutter machining concave surface automobile panel is studied. The differential geometric relationship between tool and surface at tool contact point is analyzed. According to the mathematical model of line spacing established, the optimal inclination angle of tool axis is obtained. The trajectory simulation and machining efficiency analysis of concave surface are carried out. After the optimal direction of cutting tool is obtained, the transformation relationship between coordinate systems is determined, and the attitude of workpiece is adjusted to the optimum. Compared with the traditional method and the method in this paper, the correctness of the method is verified by comparing the concave surface with the traditional method and the method in this paper. Finally, the phenomenon of over-cut interference in the machining of convex surface automobile panel with ring cutter is studied. Through the analysis of the causes of interference, the method of eliminating interference is determined, and the machining experiment of convex surface is carried out to determine the position of interference point. After the tool is adjusted to the optimal attitude, the tool path is re-programmed by the method of path densification to eliminate the interference. Compared with the traditional method and the method in this paper, the feasibility of this method is verified by comparing the convexity surface with the traditional method and the method in this paper.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG659

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