Three-dimensional process stability prediction of thin-walled workpiece in milling operation

High-speed machining of thin-walled workpiece is widely used in aerospace industry. To optimize the machining parameters in milling operations, the related process stability is required to be predicted. Compared to the existing two-dimensional (2D) milling stability model, a more completed three-dimensional (3D) regenerative process stability prediction model of thin-walled workpiece is presented based on the newly developed dynamic model. The efficiency and accuracy of the regenerative milling stability can be improved in the presented 3D model. The analysis procedure of the stability of flexible dynamic milling is developed in details. The 3D stability lobes are calculated according to the full discretization method and direct integration scheme. To verify the accuracy of presented 3D stability model, the thin-walled workpiece milling sound pressure signal and surface quality are determined in experiments.     

铣削加工粗糙度的智能预测方法

提出了一种基于最小二乘支持向量机的铣削加工表面粗糙度智能预测方法.首先进行了铣削工艺参数对工件表面粗糙度影响的正交实验,再通过对主轴转速、进给速率和切削深度三因素,以及各因素之间交互三水平实验的数据分析,找出了铣削工艺参数对工件表面粗糙度影响的一些规律.利用最小二乘支持向量机算法建立了铣削预测模型,通过该模型能在有限实验基础上利用工艺参数方便地得到粗糙度预测值.实际预测表明,在相同情况下,该模型构造速度比反向传播神经网络建模预测方法高2个～3个数量级,预测精度高10倍左右.     

Optimal fixture design in peripheral milling of thin-walled workpiece

In order to optimize the positions of the locators in peripheral milling of a thin-walled workpiece, a finite element model along with an accurate cutting forces model is proposed in this paper. The finite element model takes into account the thickness variations of the workpiece in peripheral milling. The locators on the secondary locating surface directly influence the surface errors in peripheral milling of thin-walled workpiece, so this paper deals with the optimization of the positions of the locators on the secondary locating surface. A method including two steps is presented. In the first step, the initial positions of the locators are determined by adding the locators at the position with the maximum deformation. In the second step, a heuristic algorithm is proposed to optimize the positions of the locators. Finally, a simulation example is used to illustrate the method.     

微细精密铣削表面粗糙度DRSM研究

DRSM方法具有序贯性、可旋转性、模型的稳健性以及试验次数少等优点,近年来逐渐运用在微细精密车铣加工运用中,笔者着重对微细精密铣削表面粗糙度进行DRSM分析,得出了微细精密铣削条件下工艺参数对表面粗糙度的影响规律,并进行了表面粗糙度的预测,有较强的理论实践和现实意义。     

薄壁零件的高速铣削稳定性研究

薄壁结构零件在加工过程中极易发生变形和切削振动,这对提高加工质量和加工效率十分不利.在考虑刀具和工件两个方向自由度的基础上,分析了薄壁零件的动态铣削模型.针对2A12铝合金薄壁结构零件,利用MIKRON UCPDUR0800 高速加工中心和相关仪器、软件,通过铣削力辨识实验和模态实验,进行了高速铣削薄壁零件的稳定域分析和实验验证.     

微铣金属表面微沟槽结构的粗糙度及形貌分析

为了提高和改善微沟槽表面质量,设计了高速微铣削实验,研究了微沟槽底面表面粗糙度和侧壁残留毛刺的变化规律。从理论角度引入了已加工表面的形成机理,建立了微观表面粗糙度理论模型,提出了刀具跳动对侧壁形貌变化影响的规律。利用三轴联动精密微细铣削机床加工微细直沟槽,并选取主轴转速、轴向切深、进给速度、刀具跳动量和材料组织结构为研究因素。采用多因素正交实验和极差分析法,对表面粗糙度值进行数值分析。铝合金,钢和钛合金三类微沟槽底面对应的最佳表面粗糙度值变化范围分别为1.073~1.481 μm,0.485~0.883 μm,0.235~0.267 μm;无刀具跳动钛合金微沟槽壁毛刺的最大高度为7.637 μm,而当刀具存在0.3 μm的径向综合跳动量时对应的微槽壁毛刺的最大高度为21.79 μm。铣削参数对表面粗糙度值的影响按从大到小依次为进给速度、主轴转速、轴向切深,且随着进给速度和轴向切深的增大,表面粗糙度值增大;随着主轴转速的增大,表面粗糙度值先减小后增大;在相同加工条件下,若微圆弧刀刃无磨损,微刀具的跳动量对微直沟槽侧壁表面质量有较大影响。同时,不同金属材料特性也是影响微沟槽表面质量的潜在因素。     

A dynamic surface roughness model for face milling

This paper presents a newly developed mathematical model for surface roughness prediction in a face-milling operation. The model considers the static and the dynamic components of the cutting process. The former includes of cutting conditions as well as the edge profile and the amount of runout of each insert set into a cutter body. The latter introduces the dynamic characteristics of the milling process. It is verified that such a model predicts the maximum or the arithmetic mean surface roughness value through the cutting experiments. The model can evaluate the surface texture of the precision parts machined with face milling.     

Modeling and evaluating of surface roughness prediction in micro-grinding on soda-lime glass considering tool characterization

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 ~tm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5x 107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass.     

基于粗糙度形成机理的曲面高速铣精加工参数选用

为在曲面精加工中获得理想的表面粗糙度,通过分析表面粗糙度的形成机理,建立了粗糙度与走刀行距、进给率关系的数学模型;通过实验,建立了高速曲面铣削时粗糙度与加工倾角、主运动线速度关系的图谱,实现了在生产过程中按照加工目标的表面粗糙度确定相应的走刀行距、进给率、加工倾角、主运动线速度等加工参数.研究结果表明,该研究对提高加工...     

薄壁件加工变形控制快速仿真平台开发

为控制薄壁件装夹变形和加工变形,建立了集装夹优化、加工变形预测、切削参数优化及误差补偿功能为一体的快速仿真平台.在平台实现中,装夹方案的优化采用基于形位公差控制的方法,通过多种装夹方案的比较,确定优化方案.加工变形预测时考虑了前-层变形对后-层切削深度的影响,并使切削力和加工变形达到动态平衡.为获得优化切削参数,建立了以变形控制为目标的优化模型.采用有限元法计算加工变形,采用遗传算法求解优化模型.为解得优化补偿量,仿真时考虑了变形与力的耦合效应.完成了基于ABAQUS的快速仿真平台开发.以镜座零件为例进行仿真,求得了优化的装夹方案和切削参数,验证了平台的可行性.     

Comprehensive model for predicting surface roughness of ground workpieces considering the plowing effect

Due to the stochastic nature of grinding process, a probabilistic model is considered to be the most appropriate solution for predicting the surface roughness of ground workpiece. However, the existing probabilistic models in the literature do not systematically take into account the contribution of plowing effect. As such, this work incorporates the pile-up ridges from plowing phenomenon and their overlapping effect into a probabilistic model. When the distance between two neighboring grooves left on the workpiece surface by the abrasive grains varies, the ridges will pile upon each other or the grooves will intersect with each other. These different interaction modes of grooves or ridges are discussed in the probabilistic model to predict the surface roughness. The improved Powell method is used to perform the prediction. A series of grinding experiments were performed to validate the proposed model and the result shows that the predicted values agree very well with the measured values with an average prediction accuracy of 90.4%.     

基于 IDRSN-BiLSTM 的铣削加工表面粗糙度预测方法

针对传统的表面粗糙度预测方法过度依赖人工提取特征以及预测精度较低的问题,提出一种基于 Inception 模块改进 的深度残差收缩网络( IDRSN) 和双向长短时记忆网络(BiLSTM) 的表面粗糙度预测方法。 首先,利用深度残差收缩网络 (DRSN)中软阈值化结构和注意力机制对输入信号进行降噪处理。 其次,引入 Inception 模块构建 IDRSN 以提升网络的多尺度 信息获取能力,实现自适应多尺度特征提取。 然后,引入反向长短期记忆(LSTM)构建 BiLSTM 预测网络,利用正反两个 LSTM 提高网络捕捉历史和未来完整信息的能力。 最后,进行实验验证,分别对比 IDRSN、DRSN、BiLSTM 和人工提取特征 4 种方法的 提取特征效果,以及 BiLSTM、卷积神经网络(CNN)、DRSN 和 CNN-LSTM 4 种表面粗糙度预测模型的预测精度。 结果表明所提 方法具有较高的预测精度,为铣削加工表面粗糙度预测奠定了方法基础。     

矩形薄板侧铣加工变形预测与补偿技术研究

针对目前薄壁件加工的高精度要求与铣削加工变形之间的矛盾,基于ABAQUS建立了2Al2铝合金薄壁板侧铣加工变形的有限元预测模型,得到2Al2薄壁板的加工变形曲线,并据此提出一种通过在进给方向上刀心位置偏置和刀具轴向方向偏摆来同时进行补偿的方案.最后,用试验验证了有限元预测变形的可靠性和补偿策略的有效性.     

0Cr18Ni9不锈钢焊缝高速铣削表面粗糙度试验研究

采用正交试验方法进行0Cr18Ni9不锈钢焊缝高速铣削试验,分析铣削参数对表面粗糙度的影响规律,并建立表面粗糙度的经验预测模型。结果表明:随着主轴转速的增大,表面粗糙度值减小,而随着进给速度、切削深度的增大,表面粗糙度值增大,进给速度对表面粗糙度的影响较为明显;较高的主轴转速和较低的进给速度的交互作用有利于减小表面粗糙度值,提高表面质量。     

Influence of eccentricity on roughness distributions in side milling

In this paper, a numerical model was used based on the tool-piece geometric intersection, which enables the determination of a roughness profile as a function of feed, tool radii and tool eccentricity in side milling processes. Average roughness R_a and peak-to-valley roughness R_t were obtained for a group or family of tools, defined by an average radius value and a standard deviation value of all tool radii. The Monte Carlo method was used to generate N random combinations of radius values for each family, according to a normal distribution. The model was validated by means of experimental tests. For each family of tools, roughness distributions were obtained at different feed values and for different eccentricity values. It was found that the higher eccentricity, the more asymmetrical roughness distributions become.     

复杂形状工件的端铣切削力模型

以传统的端铣切削力模型为基础，提出了一种新的端铣加工中静态切削力的预报模型。该模型考虑了复杂的工件形状和不同的铣刀进给轨迹。给出了一种新的工件和铣刀接触算法。     

Influence of minimum quantity lubrication parameters on tool wear and surface roughness in milling of forged steel

The minimum quantity of lubrication (MQL) technique is becoming increasingly more popular due to the safety of environment.Moreover,MQL technique not only leads to economical benefits by way of saving ...     

球头立铣刀铣削加工表面粗糙度仿真技术研究

铣削加工表面粗糙度的形成与铣刀和工件振动、主轴偏心、刀具磨损、刀具变形等物理和几何因素有关。多年来中外学者针对各种影响因素建立了“相对单一”的数学模型。这些数学模型只考虑了一种或两种影响因素,还没有建立起描述物理和几何变化过程的综合数学模型,为此对这些相关因素进行了深入研究,建立了基于球头立铣刀的铣削加工表面粗糙度仿真的整体数学模型。从而为虚拟数控加工仿真提供技术支撑。     

铝合金薄壁件铣削加工变形有限元分析

提出一种预测汽车主模型检具复杂薄壁件铣削加工变形的方法,将有限元技术应用于薄壁件铣削加工变形的研究中.以简单薄壁件为例,建立有限元模型,预测铣削过程中薄壁件的加工变形,并通过铣削实验对有限元分析结果进行验证,为汽车主模型检具制造工艺的技术改进提供理论依据.