飞机蒙皮数字化制造技术应用研究

随着科学技术的迅猛发展,以数字化为核心的制造技术给航空工业带来了史无前例的变革和飞跃。在飞机蒙皮制造领域,逐步形成了以数字量传递为核心,基于可重构柔性多点模具的蒙皮数控拉形技术、基于离线测量闭环形状控制的柔性模具数控拉形工艺优化技术以及可重构柔性夹持数控切边技术的飞机蒙皮数字化制造技术体系,成功实现了从蒙皮零件三维数模设计、工艺仿真和优化、数控成形、数字化检测到最终零件的柔性化、数字化和精确化制造。     

面向飞机蒙皮柔性夹持数控切边的定位仿真系统及应用

针对切边过程中有效定位点动态变化的特征,提出＂X-2-1＂动态定位原理。基于几何约束关系实现了柔性工装对曲面零件的虚拟装夹,精确计算出柔性工装的调形参数。通过协调单元生死顺序和铣削力加载,实现了切边过程有限元仿真分析。选择典型飞机蒙皮零件进行了集成验证试验,试验分析结果表明加工精度满足制造要求。     

一种面向数控工艺参数优化的铣削过程动力学仿真系统研究

针对当前国内数控加工过程中工艺参数选择和优化存在的问题,在对国内外铣削过程动力学建模、仿真和优化进行深入研究的基础上,开发了一套面向数控铣削加工过程的动力学仿真优化系统。该系统以Matlab-GUIDE为软件开发平台,可以快速、有效地预测铣削加工过程中刀具的瞬时铣削力、主轴功率、主轴转矩等物理量,预测加工表面的形貌与刀具的振动情况。同时,借助于实验模态分析结果,可以准确地计算出整个系统的稳定切削区域,为数控机床工艺参数的合理、有效选择提供了有益的指导和理论依据。整个仿真系统的主要功能在多台数控加工中心上得到了成功的验证。     

基于加工过程动力学仿真的CNC机床工艺参数选择与应用研究

针对当前数控加工过程中工艺参数选择的不确定性,以实验室已有的数控加工系统FANUC11M-MODEL A为实验研究对象,开发出一套铣削加工过程动力学仿真优化系统.利用该系统,可以在实际数控加工前有效地预测出刀具铣削力、主轴功率、主轴转矩、工件与刀具的振动等物理量的变化.同时,基于实验模态分析,可以准确地计算出整个CNC系统的稳定切削区域,为CNC机床的工艺参数的合理、有效的选择提供了有益的指导.     

数控铣削加工过程动力学仿真技术研究与应用进展

数控加工过程动力学仿真技术越来越受到国内外制造业和学术界的重视与研究,是工艺参数选择和优化的前提和基础.本文以数控铣削加工过程为研究对象,对动力学仿真技术的发展和研究现状进行了论述,重点介绍了本实验室开发出的一套铣削加工过程动力学仿真优化系统.利用该系统可以对数控切削加工中的动态铣削力、主轴功率、主轴转矩、工件与刀具的振动变形等变量进行计算与仿真,基于仿真系统分析,可以准确地计算出整个加工过程的稳定切削区域,为数控切削过程工艺参数的合理有效选择提供依据和指导.     

数控铣削加工过程动力学仿真技术研究与应用进展

数控加工过程动力学仿真技术越来越受到国内外制造业和学术界的重视与研究，是工艺参数选择和优化的前提和基础。本文以数控铣削加工过程为研究对象，对动力学仿真技术的发展和研究现状进行了论述，重点介绍了本实验室开发出的一套铣削加工过程动力学仿真优化系统。利用该系统可以对数控切削加工中的动态铣削力、主轴功率、主轴转矩、工件与刀具的振动变形等变量进行计算与仿真，基于仿真系统分析，可以准确地计算出整个加工过程的稳定切削区域，为数控切削过程工艺参数的合理有效选择提供依据和指导。     

模具平面铣削加工动态仿真研究

在平面铣削颤振产生机理的基础上,简单论述了一种更精确有效的动态铣削力理论模型的建立过程,该模型充分考虑瞬态切屑的厚度及有效前角对动态铣削力的影响。在此基础上,运用数字仿真技术在频域内建立起动态铣削力和刀具-工件系统的相对振动位移的计算机仿真模型。利用该仿真模型,可以实时显示不同工艺参数和加工参数状态下动态铣削力的数值及其功率谱密度图形以及刀具-工件系统的动态振动位移图形。仿真结果将为预测和消除铣削过程的颤振现象,保证加工质量和加工效率,延长刀具使用寿命提供可靠的依据。     

蒙皮铣削镜像顶撑技术研究

通过分析飞机蒙皮零件的结构特性、加工难点以及传统蒙皮加工方法的缺陷,介绍了满足新一代蒙皮零件加工精度需求及绿色制造发展趋势的新型蒙皮加工技术、蒙皮镜像铣削技术。蒙皮镜像铣技术是集减薄、切边、开口、钻孔于一体化的多功能铣削技术。本章通过阐述蒙皮镜像数控编程、刀轨自适应调整及厚度精确控制3个关键技术详细介绍了蒙皮镜像铣加工工艺。通过加工、检测、监测的有效集成精确控制蒙皮加工厚度及变形,在提高加工效率的同时,保证加工质量,降低加工成本。     

球头刀铣削过程动力学模型

建立了考虑刀杆柔性的球头铣刀铣削振动模型,探讨了交变轴向力对刀杆固有频率的影响。考虑刀具动态变形和工件表面波纹对切削厚度的再生反馈,建立了球头刀铣削动力学模型,对铣削中的动态铣削力和刀杆振动进行了仿真,证明了离线仿真可以对铣削过程动特性做出预测。     

基于数值模型的数控加工中切削力与稳定域仿真

针对数控铣削加工工艺参数选择存在的问题,以球头铣刀高速铣削过程为研究对象,建立了考虑机床-刀具-工件系统振动的非线性动力学模型,分析了铣削力中的动态分量对切削颤振的影响,在考虑再生颤振的基础上建立非线性动力学模型.基于动态铣削力建模和颤振稳定域分析计算,提出了机床切削系统稳定性极限预测方法,并对其进行仿真分析,为铣削加...     

Feedrate optimization for variant milling process based on cutting force prediction

Machining process modeling, simulation and optimization is one of the kernel technologies for virtual manufacturing (VM). Optimization based on physical simulation (in contrast to geometrical simulation) will bring better control of a machining process, especially to a variant cutting process – a cutting process so complex that cutting parameters, such as cutting depth and width, change with cutter positions. In this paper, feedrate optimization based on cutting force prediction for milling process is studied. It is assumed that cutting path segments are divided into micro-segments according to a given computing step. Heuristic methods are developed for feedrate optimization. Various practical constraints of a milling system are considered. Feedrates at several segments or micro-segments are determined together but not individually to make milling force satisfy constraints and approach an optimization objective. After optimization, an optimized cutting location data file is outputted. Some computation examples are given to show the optimization effectiveness. This revised version was published online in October 2004 with a correction to the issue number.     

圆柱铣刀铣削力过程的物理建模

密切结合先进制造技术的需要,以虚拟制造技术作为研究课题,运用金属切削理论等,对铣削力建模进行了系统深入的研究.该模型中考虑了前刀面上作用的正压力和摩擦力,给出了适用于圆柱螺旋刃铣刀的三维单元铣削力模型.论文为丰富虚拟制造建模理论体系、开发实用的铣削加工过程物理仿真系统奠定了坚实的基础.     

铣削加工表面几何特征的仿真研究

基于坐标矩阵的齐次变换和矢量运算法则,建立了铣削加工过程中刀具的运动轨迹方程,并在工件离散、刀具离散和加工过程离散的基础上,设计了铣削表面形貌仿真算法,并基于MATLAB的GUI功能开发了铣削加工表面形貌仿真系统。验证结果表明,仿真结果与实验结果一致性程度高,可应用于实际铣削加工表面几何形貌的预测和分析之中。     

带再生反馈的柔性立铣刀铣削过程模型

精确合理的铣削过程模型是研究铣削加工表面形貌的关键。首先根据线性弹性体基本假设,将铣削过程中刀杆所受的力和产生的变形均分解为动、静两部分;然后运用微分几何理论,考虑实际切削过程中的再生效应,导出动态铣削力集度表达式,进而建立刀杆的动态变形模型,并构造出一套与之相应的高效快速数值仿真算法,同时还给出刀杆静态变形量的计算方法;最后通过仿真实例说明该模型的合理性。     

基于LS-DYNA的铣削过程三维仿真研究

金属铣削是一个弹塑性变形和断裂的复杂过程，基于LS-DYNA对铣削加工系统建模，对系统进行动态三维仿真，并对7075铝合金材料进行铣削力动态实验测试，将其与仿真结果进行比较，验证仿真计算可靠性，对铣削温度分布进行了分析，通过调整仿真铣削模型的参数，对铣削过程进行优化，降低铣削力的大小，保证铣削过程的稳定和加工的质量，提高切削效率。     

A novel chatter stability criterion for the modelling and simulation of the dynamic milling process in the time domain

The modelling of the dynamic processes in milling and the determination of chatter-free cutting conditions are becoming increasingly important in order to facilitate the effective planning of machining operations. In this study, a new chatter stability criterion is proposed, which can be used for a time domain milling process simulation and a model-based milling process control. A predictive time domain model is presented for the simulation and analysis of the dynamic cutting process and chatter in milling. The instantaneous undeformed chip thickness is modelled to include the dynamic modulations caused by the tool vibrations so that the dynamic regeneration effect is taken into account. The cutting force is determined by using a predictive machining theory. A numerical method is employed to solve the differential equations governing the dynamics of the milling system. The work proposes that the ratio of the predicted maximum dynamic cutting force to the predicted maximum static cutting force can be used as a criterion for the chatter stability. Comparisons between the simulation and experimental results are given to verify the new model.     

基于MATLAB的铣削加工颤振稳定域仿真算法及实现

针对国内数控铣削加工工艺参数选择存在的问题,基于动态铣削力建模和颤振稳定域分析计算,以MATLAB为开发工具,实现了铣削加工颤振稳定域仿真算法.通过模态锤击实验获得的频响函数,仿真出了整个加工系统的颤振稳定域图形,为进行铣削加工切削参数选择和优化提供了理论依据.验证实验证实了仿真算法的有效性和准确性,仿真方法在工厂得到了实际应用并取得了良好的应用效果.     

基于密度函数的三维复杂槽型铣刀片物理场分析

以哈尔滨理工大学开发的波形刃(前刀面为波形曲面)铣刀片为例,在铣削力数学模型基础上,通过铣削力试验以及切屑与前刀面接触面积试验,建立了三维复杂槽型铣刀片前刀面的受力密度函数;基于该函数,对波形刃铣刀片进行了应力场分析。在铣削温度数学模型基础上,运用传热学理论,建立了波形刃铣刀片表面受热密度函数;基于该函数,对波形刃铣刀片进行了温度场分析。这些研究结果可为槽型优选技术的研究打下理论基础。     

Modeling and Analytical Solution of Chatter Stability for T-slot Milling

T-slot milling is one of the most common milling processes in industry. Despite recent advances in machining technology, productivity of T-slot milling is usually limited due to the process limitations such as high cutting forces and stability. If cutting conditions are not selected properly the process may result in the poor surface finish of the workpiece and the potential damage to the machine tool. Currently, the predication of chatter stability and determination of optimal cutting conditions based on the modeling of T-slot milling process is an effective way to improve the material removal rate(MRR) of a T-slot milling operation. Based on the geometrical model of the T-slot cutter, the dynamic cutting force model was presented in which the average directional cutting force coefficients were obtained by means of numerical approach, and leads to an analytical determination of stability lobes diagram(SLD) on the axial depth of cut. A new kind of SLD on the radial depth of cut was also created to satisfy the special requirement of T-slot milling. Thereafter, a dynamic simulation model of T-slot milling was implemented using Matlab software. In order to verify the effectiveness of the approach, the transfer functions of a typical cutting system in a vertical CNC machining center were measured in both feed and normal directions by an instrumented hammer and accelerators. Dynamic simulations were conducted to obtain the predicated SLD under specified cutting conditions with both the proposed model and CutPro?. Meanwhile, a set of cutting trials were conducted to reveal whether the cutting process under specified cutting conditions is stable or not. Both the simulation comparison and experimental verification demonstrated that the satisfactory coincidence between the simulated, the predicted and the experimental results. The chatter-free T-slot milling with higher MRR can be achieved under the cutting conditions determined according to the SLD simulation.