【作者】 王涛；

【导师】 王敏杰； 蔡玉俊；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 模具是工业生产的基础工艺装备,高精度、短工期、低成本是其必然发展方向。模具工业必须广泛应用数字化制造技术以缩短模具的生产工期。模具数控加工作为数字化制造的一种重要手段,是影响模具生产工期长短和质量的主要因素,而模具型腔数控加工是模具数控加工中难度最大、最耗时的部分。但是传统的模具型腔数控加工中常采用恒定、保守的进给速度,从而导致加工效率大大降低。因此,如何在保证加工质量的前提下,提高模具型腔的数控加工效率成为一个亟待解决的难题。 针对模具型腔数控加工中常用的球头铣刀,本文进行了基于瞬时铣削力模型的数控加工进给速度优化研究,具体内容如下: 在工件Z-Map表示模型和刀刃离散点表示模型的基础上,针对球头铣刀铣削运动轨迹,提出了球头铣刀加工复杂曲面的表面形貌微观几何仿真算法。微观几何仿真提供了精确切屑几何轮廓,为后续铣削力预测模型的建立提供必要的几何参数。 在微观几何仿真的基础上,建立了考虑剪切力和犁切力双重效应的球头铣刀铣削力预测模型。通过正交切削实验回归出其中的犁切力系数和剪切力系数,将几何仿真得到的几何参数输入铣削力预测模型,即可预测出球头铣刀的瞬时铣削力。 以球头铣刀瞬时铣削力模型预测的铣削力为依据,针对不同刀位点处的切削载荷,求出相应的进给速度,然后将进给速度相近的刀位点进行分段,每段的进给速度选取该段的最低值并圆整,最后将优化的进给速度值反写回原始NC程序的相应刀位点处,即可得到高效而合理的NC程序。 实践证明,本文提出的进给速度优化方法高效而合理,在保证加工质量的前提下,有效地提高了模具型腔数控加工的效率。更多还原

【Abstract】 Die & Mould is the basic technical equipment for industrial manufacturing. High accuracy, short manufacturing cycle and lower cost are its necessary developing direction. So digitized manufacturing technology must be widely used in Die & Mould industry in order to shorten the manufacturing cycle. As a significant machining means of mould, NC machining is one of the most important factors which influences the mould manufacturing cycle and quality. Further more, NC machining of mould cavity is the most difficult and time-consuming part. But the traditional NC machining always adopts a constant, conservative feedrate, which results in a very low machining efficiency. Therefore, how to improve the NC machining efficiency of mould cavity without losing machining quality has become an urgent problem to be solved.This paper researches on the optimization of NC machining feedrate based on the milling force prediction model of the ball-end mill which is popular in NC machining of mould cavity. The main research contents are as follows:According to the Z-Map model for workpiece and the discrete points model for cutter and the dynamic track of ball-end mills, an algorithm for micro-geometric simulation of sculptured surface machining with ball-end mill is presented. The micro-geometric simulation provides the precise profile of the chip, which becomes the most important geometric parameter for subsequent milling force prediction.Based on the micro-geometric simulation, a milling force prediction model for ball-end mill considering ploughing force and shearing force is presented. The ploughing coefficients and the shearing coefficients are regressed from orthogonal cutting tests. Then the instantaneous milling force can be predicted by inputting the geometric parameters from geometric simulation to the milling force prediction model.According to the instantaneous milling force from the milling force prediction model, the relevant federates on different cutter-location points are evaluated by its cutting load. Then the cutter-location points are divided into pieces due to close feedrates. The lowest feedrates of each piece are adopted and rounded up to be the whole piece’s feedrates. Finally, an efficient and rational NC program can be gained by rewriting the optimized feedrates back to the original NC program.Experiments have proved that the feedrate optimization means presented in this paper is efficient and rational, which effectively improves the NC machining efficiency of mould cavity without losing machining quality.更多还原