Tricept型并联机床曲面加工的刀轨规划

研究了Tricept型并联机床采用平底刀加工曲面时的刀轨规划问题. 首先简要地介绍了机床的结构组成,并对机床的逆运动学及其位姿作业空间进行了分析. 在此基础上,给出了刀具干涉检验及刀具位姿作业空间检验的有效算法. 借助于传统五坐标数控机床曲面加工的等残高刀轨路径生成方法,提出了适用于Tricept型并联机床的刀轨规划算法.     

基于特征的汽轮机叶片参数化设计软件

为了给叶片专用加工软件提供可用的叶片基础模型,开发了基于特征的叶片参数化设计软件.针对汽轮机叶片的结构特点,将叶片分为叶根、根面、叶冠、冠面和叶身5个特征,而叶身又可以分成背弧曲面、进汽边圆弧曲面、内弧曲面和出汽边圆弧曲面4个特征.软件可根据用户输入的叶片参数,对各个特征分别造型,生成可用于开发叶片专用加工软件的叶片三维模型.仿真结果表明:用该方法生成的叶片模型,可分别对叶身的不同部分赋以不同的切削速度和进给量,从而避免过切.基于特征的叶片参数化模型可为叶片加工提供实用的基础模型.     

基于NN与GA的曲面加工适应学习控制研究

提出了适用于曲面加工条件的适应学习控制方法,在回避加工振动的前提下以实现高效效率加工为目的,将遗传算法（GA）的优化机能与神经网络（NN）的学习机能相融合,建立了由开放式CNC加工机床,多维传感器,实时控制器,学习模型及优化模型组成的曲面加工适应学习控制系统、切削实验结果表明所提出的加工条件适应控制系统可有效地抑制曲面切削振动,提高了切削加工效率。     

基于遗传算法的电火花加工电参数优化模型

电火花加工中电参数的选择对加工结果有很大影响，其影响程度难以用精确的数学模型来表示，针对这种情况，提出了一个基于遗传算法的电火花加工电参数的优化模型；它模仿熟练操作者的决策过程，利用遗传算法从工艺数据和加工实例中抽取出反映电参数和加工结果之间关系的模糊产生式规则，当有新的加工要求时，基于这些模糊产生式规则，通过模糊推理就可以提供一组合适的电参数，从而实现了电参数的优化。     

Circular Interpolation Algorithms of 5-Axis Simultaneous CNC System

Spatial circular arc can be machined conveniently by a 5-axis NC machine tool.Based on the data sampling method,circular interpolation in two-dimensional plane is discussed briefly.The key is to solve the problem of circular center ex- pressed in the workpiece coordinate system by means of the transformation matrix.Circular interpolation in three-dimensional space is analyzed in detail.The method of undetermined coefficient is used to solve the center of the spatial circle and the method of coor- dinate transformation is used to transform the spatial circle into the XY-plane.Circular arc in three-dimensional space can be ma- chined by the positional 5-axis machining and the conical surface can be machined by the continuous 5-axis machining.The velocity control is presented to avoid the feedrate fluctuation.The interpolation algorithms are tested by a simulation example and the inter- polation algorithms are proved feasible.The algorithms are applied to the 5-axis CNC system software.     

NURBS自由曲线、曲面的等距算法及其在数控加工中的应用

推导了NURBS曲线、曲面的各阶导矢、等距曲线曲面的各阶导矢及其曲率的计算公式，分析了参数曲线曲面线性插值误差，讨论了插值等距曲线曲面上点的采样原则，B样条形式表达的插值曲线曲面的求解方式以及减少B样条形式表达的插值曲线曲面的数据冗余的方法，最后将上述理论应用于两轴联动行切加工的刀位计算。     

Decomposition and reconstitution principle for complex surfaces and its applications

Though there are already a variety of models for complex surfaces, they are not so convenient as needed in practice. A hierarchical model and the principle of decomposition and reconstitution for complex surfaces have been proposed, which have the potential to enhance the support of automated design systems on creative work intelligently Then the progress made is discussed involving the applications of the new principle in the following three areas:conjugation surface calculation, tool path generation in numerically controlled machining, and machining process innovation by re-recognition     

成形刀在模具数控加工中的应用

论述了在模具过渡曲面数控加工中采用成形刀代替球头刀的可能性及其优点，并对成形刀加工中的一些问题及其解决方法进行了研究。     

适于高速加工的五次参数样条曲线插补及其速度生成算法的研究

为适应高速高精加工,针对传统插补算法和速度控制方式在进给过程中存在柔性冲击的问题,提出了一种五次参数样条曲线插补方法及其速度生成算法.该算法采用二阶连续可导的五次样条和近弧长样条参数提高了进给运动的连续性;速度控制算法保证机床在高速运行过程中加加速度(加速度的变化率)的二次连续、加速度、速度和位移与时间关系的高阶连续变化,并且保证在各自的约束范围内,从而使机床的运动平稳,避免产生大的冲击和振动,同时有利于提高加工质量,减少加工时间.通过仿真验证,表明了这种算法能有效地保证高速加工机床运行过程中进给速度的连续性和运动轮廓的平滑性.     

Adaptive compensation of sculptured surface machining errors by open architecture manufacturing system

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基于k-均值聚类算法的模具型腔曲面分片加工研究

为了提高复杂曲面的加工效率,解决编程人员凭经验分片导致加工特征遗漏和区域参数不合理的问题,提出了一种基于k-均值聚类的模具型腔曲面分片方法.首先,将型腔曲面根据曲面加工特点进行分类;然后,根据k-均值聚类分析原理,将型腔曲面上加工特性相似且相邻的点归集到一个加工区域内;进而,型腔曲面被分割成若干具有不同加工特性的曲面片;最后,针对每个曲面片的特性规划刀具路径实施分片加工,将接刀痕迹控制在曲面片的交接处,以达到提高效率及加工表面质量的目的.结果表明,此方法能明显减少加工轨迹的长度,提高加工的效率及质量.     

Continuity control method of cutter posture vector for efficient five-axis machining

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.     

Research on Manufacturing Technology Based on Machine Vision

The concept of machine vision based manufacturing technology is proposed first,and the key algorithms used in two-dimensional and three-dimensional machining are discussed in detail.Machining information can be derived from the binary images and gray picture after processing and transforming the picture.Contour and the parallel cutting method about two-dimen- sional machining are proposed.Polygon approximating algorithm is used to cutting the profile of the workpiece.Fill Scanning al- gorithm used to machining inner part of a pocket.The improved Shape From Shading method with adaptive pre-processing is adopted to reconstruct the three-dimensional model.Layer cutting method is adopted for three-dimensional machining.The tool path is then gotten from the model,and NC code is formed subsequently.The model can be machined conveniently by the lathe, milling machine or engraver.Some examples are given to demonstrate the results of lmageCAM system,which is developed by the author to implement the algorithms previously mentioned.     

工程陶瓷引弧微爆炸加工过程的高速摄像

为了研究工程陶瓷引弧微爆炸加工的工作原理,建立了高速摄像试验系统对微爆炸等离子体射流的产生过程、外观形态进行了观测,得到了微爆炸等离子体射流的产生原理.对氮化硅陶瓷和氧化铝陶瓷冲击蚀坑的形成过程进行了高速摄像观测,并利用扫描电镜观察了冲击蚀坑的截面形貌,得到了陶瓷加工的材料去除机理.实验结果表明,等离子体射流的形成过程可分为火花放电和稳定等离子体射流2个阶段,等离子体射流的直径随着电流值的增大而增大,冲击蚀坑直径随着加工时间逐渐扩展.氮化硅陶瓷加工时升华分解,蚀坑表面覆盖一层结构疏松的变质组织,在亚表面上有横向裂纹形成;氧化铝陶瓷加工时直接熔化,表面变质层成分为非晶体玻璃相.     

ZA22／Al_2O_3f复合材料的机械加工与表面粗糙度

通过对ＺＡ２２／Ａｌ２Ｏ３ｆ复合材料机械加工表面粗糙度的研究，得知合理选择切削参数是提高加工表面质量、降低表面粗糙度的重要手段。高的切削速度、小的进给量及小的切削深度对提高该复合材料的表面质量有益。在同一车削条件下，该复合材料表面质量优于ＺＡ２２合金及４５＃钢，且表面粗糙度随着ＺＡ２２／Ａｌ２Ｏ３ｆ短纤维体积含量的增加而降低。表明了该复合材料具有良好的加工性     

Influence and Optimization of Surface Roughness on Surface Integrity during Turning Using Grey Relational Analysis

Current machining studies have reported effects of prevalent and common factors, while ultra-high finish requires holistic approach to identify all factors and investigate their effects on machining of hard to machine materials. In this work, a less investigated yet important factor, roughness of the uncut surface, was studied, and its effects on the individual response, i.e., surface finish of the machined part, were found to be significant. AISI 316, which is mainly applied in strategic areas, was selected and three effective turning factors, cutting speed (A), feed rate (B), and roughness of the uncut surface (C) on three output responses including surface roughness of the machined surface (R_a), microhardness(HV), and material removal rate (MRR), were reported. Further, single response optimization of the individual output response and multi-response optimization of all the three responses were carried out. Taguchi L₉ orthogonal array based signal-to-noise (S/N) ratio method was used for individual response optimization, and grey relational analysis (GRA) was employed for multi-response optimization. Effects of the process factors on the output responses were evaluated through inclusive statistical analyses. The individual response optimization revealed that there was a considerable effect of roughness of the uncut surface on the machining performance. Results of the GRA illustrated that the speed during the cutting process and the feed rate had substantial trace on the surface integrity (indicated by R_a and HV) and production rate (indicated by MRR), while roughness of the uncut surface did not have a significant effect.     

汽车覆盖件模具的非球头刀宽行加工方法

汽车覆盖件模具型面一般是由大面积平坦面和一定陡立面结合的构成的自由曲面.针对汽车覆盖件模具粗加工及半精加工中球头刀效率低的问题,将非球头刀的宽行加工应用于汽车覆盖件模具粗加工与半精加工过程,在工艺上使用环形刀加工陡立面,高进给铣刀加工平坦面的组合加工方式来代替普通球头刀加工,论述了高进给铣刀在加工平坦类曲面中的优势,提出了平底类刀具铣削平坦凹曲面的最小曲率半径判定原则,并对环形刀和高进给铣刀铣削区域内的刀路轨迹进行优化.最后,在三轴数控机床上进行了实验验证,实验结果表明:宽行加工工艺与球头刀加工相比可提高加工效率44.75%.     

曲面加工中进刀策略的自适应研究

通过对自由曲面数控加工中残留高度的分析,得出结论：用球铣刀加工曲面时,理论粗糙度与铣刀半径、表面曲率、参数曲线斜率等有关。在此基础上, 提出了基于参数曲线曲率的自适应进刀方法和全面曲面的等误差、均匀粗糙度加工概念,建立了能实现这种加工的进刀策略模型及其算法。分析表明：该模拟所确定的进刀路径,在一定精度下效率高于等步距方法。     

螺旋桨叶片曲面数控加工几何模型研究

目前在螺旋桨叶片曲面数控加工中,普遍存在着加工效率太低的现象,如何在保证加工精度的前提下提高加工效率已成为急待解决的问题。难过给出一般螺旋桨叶片工作面的方程,应用微分几何理论推导了数控加工所用球头铣刀的最大允许半径计算公式、走刀步长以及切削行距的计算公式,给出了根据刀具运动包络面计算实际加工误差的方法,最后通过实例验证了所建立模型的可行性和可靠性,为提高螺旋桨叶片曲面的加工效率提供了有效途径。     

复杂曲面铣削加工参数双神经网络优化方法研究

针对复杂曲面加工效率低、能耗高、表面质量难控制的问题,以及加工参数和目标之间关系确定的难题,建立了考虑复杂曲面特征的双神经网络优化方法。首先,用曲率表示复杂曲面加工复杂度来描述曲面特征,以曲面加工复杂度、主轴转速、进刀量、进给速度和路径间距为设计变量,以加工时间、能量消耗和表面粗糙度为目标函数,建立了复杂曲面加工参数的优化数学模型;其次,采用BP神经网络以黑箱法建立加工参数与优化目标的非线性关系,结合ALM神经网络方法对加工参数进行了优化。该方法解决了复杂曲面加工参数的优化问题,对提高复杂曲面加工效率和质量有一定的理论指导作用。