Development of practical postprocessor for 5-axis machine tool with non-orthogonal rotary axes

In order to develop a practical postprocessor for 5-axis machine tool,the general equations of numerically controlled(NC) data for 5-axis configurations with non-orthogonal rotary axes were exactly expressed by the inverse kinematics,and a windows-based postprocessor written with Visual Basic was developed according to the proposed algorithm.The developed postprocessor is a general system suitable for all kinds of 5-axis machines with orthogonal and non-orthogonal rotary axes.Through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment,the effectiveness of the proposed algorithm is confirmed.Compatibility is improved by allowing exchange of data formats such as rotational total center position(RTCP) controlled NC data,vector post NC data,and program object file(POF) cutter location(CL) data,and convenience is increased by adding the function of work-piece origin offset.Consequently,a practical post-processor for 5-axis machining is developed.

Flame image recognition of alumina rotary kiln by artificial neural network and support vector machine methods

Based on the Fourier transform, a new shape descriptor was proposed to represent the flame image. By employing the shape descriptor as the input, the flame image recognition was studied by the methods of the artificial neural network(ANN) and the support vector machine(SVM) respectively. And the recognition experiments were carried out by using flame image data sampled from an alumina rotary kiln to evaluate their effectiveness. The results show that the two recognition methods can achieve good results, which verify the effectiveness of the shape descriptor. The highest recognition rate is 88.83% for SVM and 87.38% for ANN, which means that the performance of the SVM is better than that of the ANN.

ACCURATE MEASUREMENT OF ROTARY MACHINE AXIS CENTER TRACE

Four methods aiming at measuring rotary machine axis center trace arediscussed in detail. The comparative analysis is made on some aspects such as measurement accuracy,on-machine characteristics, feasibility, practical operation convenience and the integrity ofmeasurement information. In order to simplify measurement, the axis profile error is ignored intraditional condition, while the measurement accuracy will be reduced. The 3-point method that theaxis profile error is firstly separated has better real time character, at the same time, not onlythe axis motion error but also the axis profile error can be measured. All of those information canbe used to diagnose the fault origin. The analysis result is proved to be correct by the experiment.

Fault Diagnosis of a Rotary Machine Based on Information Entropy and Rough Set

There exists some discord or contradiction of information during the process of fault diagnosis for rotary machine. But the traditional methods used in fault diagnosis can not dispose of the information. A model of fault diagnosis for a rotary machine based on information entropy theory and rough set theory is presented in this paper. The model has clear mathematical definition and can dispose both complete unification information and complete inconsistent information of vibration faults. By using the model, decision rules of six typical vibration faults of a steam turbine and electric generating set are deduced from experiment samples. Finally, the decision rules are validated by selected samples and good identification results are acquired.

Analysis of Machinable Structures and Their Wettability of Rotary Ultrasonic Texturing Method

Tailored surface textures at the micro- or nanoscale dimensions are widely used to get required functional performances. Rotary ultrasonic texturing （RUT） technique has been proved to be capable of fabricating periodic micro- and nanostructures. In the present study, diamond tools with geometrically defined cutting edges were designed for fabricating different types of tailored surface textures using the RUT method. Surface generation mechanisms and machinable structures of the RUT process are analyzed and simulated with a 3D-CAD program. Textured surfaces generated by using a triangular pyramid cutting tip are constructed. Different textural patterns from several micrometers to several tens of micrometers with few burrs were successfully fabricated, which proved that tools with a proper two-rake-face design are capable of removing cutting chips efficiently along a sinusoidal cutting locus in the RUT process. Technical applications of the textured surfaces are also discussed. Wetting properties of textured aluminum surfaces were evaluated by combining the test of surface roughness features. The results show that the real surface area of the textured aluminum surfaces almost doubled by comparing with that of a flat surface, and anisotropic wetting properties were obtained due to the obvious directional textural features.

Active vibration control of spindle in ultra-precision turning machine

In order to minimize vibration and improve rotary precision of spindle, we apply active vibration control technique to ultra-precision turning machine based on the analysis of vibration characteristic of aerostatic bearing spindle. Using aerostatic bearing itself as actuator, the vibration of spindle is controlled by adjusting admission pressure respectively and by changing pressure distribution in the bearing. The experiments and simulations prove that this method can minimize the vibration of spindle effectively.

A Wavelet Spectrum Technique for Machinery Fault Diagnosis

Rotary machines are widely used in various applications. A reliable machinery fault detection technique is critically needed in industries to prevent the machinery system’s performance degradation, malfunction, or even catastrophic failures. The challenge for reliable fault diagnosis is related to the analysis of non-stationary features. In this paper, a wavelet spectrum (WS) technique is proposed to tackle the challenge of feature extraction from these non-stationary signatures;this work will focus on fault detection in rolling element bearings. The vibration signatures are first analyzed by a wavelet transform to demodulate representative features;the periodic features are then enhanced by cross-correlating the resulting wavelet coefficient functions over several contributive neighboring wavelet bands. The effectiveness of the proposed technique is examined by experimental tests corresponding to different bearing conditions. Test results show that the developed WS technique is an effective signal processing approach for non-stationary feature extraction and analysis, and it can be applied effectively for bearing fault detection.

精密镗床旋转轴几何误差完备性测量与辨识

针对四轴卧式镗床旋转轴需测几何误差的数目不统一与完备性缺失的问题,提出了基于形状创成函数的四轴卧式镗床旋转轴PIGEs形成机理分析方法与旋转轴完备几何误差测量辨识方法。基于形状创成机理构建了卧式镗床几何误差创成函数,确定了旋转轴可通过误差补偿进行调整的最少与位置无关的几何误差(Position-independent geometric error, PIGEs)数目。建立了卧式镗床旋转轴4项PIGEs、6项与位置有关的几何误差(Position-dependent geometric error, PDGEs)、6项安装误差(Setup error, SEs)与球杆仪(Double ball bar, DBB)测量轨迹半径之间的完备性函数模型,设计了基于DBB的四轴联动Viviani曲线测量轨迹,构建了旋转轴6项PDGEs的NURBS表征与PIGEs、SEs辨识方法。开展了误差补偿对比实验验证,结果表明,利用几何误差完备性测量与辨识结果进行误差补偿,较仅单一补偿6项PDGEs可提升圆轨迹测量精度40.69%。

参数优化的IZOA-SVM机械设备故障诊断方法

在复杂的工作环境中,机械设备振动信号的复杂性常常会导致机械设备故障诊断的准确性不高,为解决设备运行中因信号复杂性引发的故障诊断难题,提出了一种参数优化的斑马优化算法优化支持向量机(IZOA-SVM)的故障诊断方法。首先,引入了柯西变异和反向学习的改进策略到斑马优化算法(ZOA)中,提出了改进的斑马优化算法(IZOA),旨在改善原有斑马优化算法在迭代后期容易陷入局部极值等问题,从而有效增强了其全局搜索能力;其次,利用IZOA优化支持向量机(SVM)的核参数g和惩罚参数c以寻找SVM最优参数组合[c,g],并构建了IZOA-SVM模型;然后,计算了样本的13个时域特征以构成特征向量,并将特征向量分别输入到IZOA-SVM模型、斑马优化算法优化支持向量机(ZOA-SVM)模型、粒子群算法优化支持向量机(PSO-SVM)模型、遗传算法优化支持向量机(GA-SVM)模型和支持向量机模型,进行了故障分类;最后,通过旋转机械振动及故障模拟试验验证了该方法的有效性。研究结果表明:IZOA-SVM模型在分类准确率方面得到了明显的提高,达到了98.33%;该模型能够精准而稳定地识别故障类型,提高故障识别的准确性,在准确率方面相较于其他对比方法表现出更为显著的优势。因此,该方法在全局搜索和故障分类准确性方面都取得了明显的改进,为复杂环境下的故障诊断提供了可参考的解决方案。

面向切削力修正的机床主轴回转精度预测实验分析

为了提高机床控制精度,设计一种可以精确预测面向切削力修正的主轴回转精度分析方法。为验证回转精度预测准确性,建立一套不需要通过标准球实现的主轴回转精度分析系统,可以针对具体切削工况开展主轴回转精度测试。研究结果表明:随着进给速率和切削深度改变,形成了具有规律性的同步误差,切深受到同步误差因素的影响程度最大,而进给速度次之。受切削载荷影响,主轴回转精度显著改变,同步误差和切削载荷具有正相关关系。在变进给及变切宽条件下,测试结果与仿真结果相近,最大误差为0.2μm。设定切宽12 mm与进给速度1200 mm/min时,分离得到的圆度误差与100 r/min空转时圆度误差相比相吻合。

陶瓷基复合材料超声振动辅助加工技术研究现状

陶瓷基复合材料具有高硬度、高强度、高耐磨性和耐腐蚀性等一系列优点,在航空航天、特种防护等领域具有极大的应用前景,同时陶瓷基复合材料的高精度高效率加工依靠传统机械生产方式难以实现。超声振动辅助加工技术在陶瓷基复合材料的深小孔、薄壁和复杂型面加工等领域应用日益广泛,并形成了特有的行业体系,是精密、超精密制造领域发展的重要方向。针对近年来陶瓷基复合材料的超声振动辅助加工技术的发展状况,概述了陶瓷基复合材料和超声振动系统的研究现状,系统介绍了陶瓷基复合材料加工领域超声振动辅助磨削、钻削以及旋转超声加工和微细超声加工的应用和研究现状,并对超声振动辅助加工技术的应用趋势进行了总结和展望。

超声辅助铣削钛合金工艺研究

由于钛合金的可加工性较差,采用传统机械加工技术难以实现高精度加工。超声加工通过对工具头施加振动来改善加工效果,将其引入钛合金加工可提高钛合金的加工性能。为提高钛合金的加工性能,分别以侧面铣削和端面铣削两种形式开展了超声辅助铣削钛合金工艺试验,探究了不同切削参数与切削形式的旋转超声加工对钛合金铣削加工的影响,并测量加工过程的切削力、加工后的工件表面粗糙度及其表面微观结构。结果表明:在侧面铣削时,超声辅助可减少加工过程中的振动、降低切削力及提高工件表面质量;在端面铣削时,超声辅助会降低加工过程的切削力,但在加工中由于超声振动作用于工件表面形成了微织构,虽然提高了工件表面形貌的均匀性,却也增大了工件的表面粗糙度值。

卧式加工中心转台回转夹具定位销连线的数学建模及实例应用研究分析

卧式加工中心转台回转夹具的典型结构是通过在卧式加工中心工作台上配置转台、尾座和夹具体,进而构成摇篮式转台,该种方式可以使加工工序集中化,进一步提高零件的加工质量和加工效率。在基于摇篮式转台回转夹具构成型式分析的基础上,以定位销连线为研究对象,通过讨论定位销连线与转台回转轴线及机床坐标系三者之间平行关系的几种情况,进而建立数学模型,并通过实例的方式解决生产过程中遇到的实际问题。

深度超圆盘分类器及其在旋转机械故障诊断中的应用

几何模型分类器具有坚实的几何统计基础和良好的泛化能力,因此在旋转机械故障诊断中取得了较高的分类精度。与仿射包和凸包相比,超圆盘(Hyperdisk,HD)对样本分布区域的估计更加合理。但超圆盘模型属于浅层学习模型,对复杂函数的表示能力有限,存在学习能力和泛化能力差等缺点。针对这个问题提出一种深度超圆盘分类器(Deep Hyperdisk Large Margin Classifier,DHD),该方法通过模块叠加的方式将超圆盘分类器深度化,利用特征提取公式从每层模块的输入样本中自主提取新的特征值,并将其应用在下一层模块的训练学习中。将所提方法应用到旋转机械故障诊断当中,实验结果表明该方法对故障样本的分类准确率高于其他模型算法,且对不均衡样本和强噪声背景下的故障样本均具有良好的分类能力。

种子破损率快速检测方法研究

旋耕播种机推广鉴定时,需要人工检测种子的破损率。为提高检测效率,以小麦种子为例,对种子破损率快速检测方法进行研究。设计种子破损率自动检测平台,可一次性采集50 g小麦种子图像,基于图像处理技术和机器学习方法,提取小麦种子图像13个形状特征和8个纹理特征,建立基于特征的种子破损识别模型;识别的破损种子图像与种子质量的关系,建立基于图像的破损种子质量预测模型,按照鉴定大纲要求实现小麦种子破损率的快速检测。对江苏省“丹阳001”“A888”“泰州014”“无锡004”4个品种的小麦种子破损率进行试验测试,每个品种3次取样测定。结果表明:4个品种小麦种子破损率自动检测的平均相对误差分别为0.08%、0.07%、0.06%、0.08%,检测的相对均方根误差为0.08%,检测平均时长为5.216 s。该研究实现小麦种子破损率自动、快速检测,节省农机鉴定时间,推动农机鉴定过程的标准化和智能化。

基于新型旋转-直线往复机构的切片机设计分析及参数优化

针对现有糕点切片机切片效率和质量低下的问题,进行基于新型旋转-直线往复机构的切片机设计分析及参数优化。首先对切片机构型设计及椭圆导轨长短径比和转速进行计算,然后进行运动学和静力学分析,接着分别在不同长短径比和转速动力学仿真分析基础上,构建切刀的加速度均值和均方根值三次多项式拟合方程作为目标函数,利用NSGA-Ⅱ遗传算法进行长短径多目标参数优化及转速择优,最后搭建样机完成不同转速对比实验及玉米饼切片性能测试。结果表明,最优长短径和转速分别为190 mm、120 mm和20 r/min,优化后切刀效率提高75%,切刀进刀加速度的最大和平均误差分别减小26%和49%,退刀加速度的最大和平均误差分别减小60%和63%,玉米饼切面整齐美观,验证了设计的可行性。

玉米精量播种复合作业机具设计及试验

针对现有玉米播种机播种精度以及播种合格指数较低的问题,设计一种玉米精量播种复合作业机具。阐述播种复合作业机具的工作原理以及主要技术参数,一次进地可同时完成苗带旋耕、施肥、精量播种、覆土和镇压等工作。选用苗带旋耕,并对旋耕机构作业运动状态进行理论分析,确定旋耕刀周向排列,来达到保护性耕作和提高播种精度的要求。确定平行四连杆仿形机构的总体结构,并对其进行受力和尺寸参数分析,通过计算得到仿形机构的杆长,使播种单体有足够的仿形量,保证播深一致性。选用气吸式排种器,确定气吸式排种器结构,计算得出排种器最高转速,可达到精量播种的目的。在黄淮海地区进行田间试验,结果表明:当播种机作业速度为4 km/h,苗带旋耕机构转速为280 r/min时,机具通过性良好,苗带宽度合格率为93.5%,播深合格率为93.1%,粒距合格率为93.5%,重播率为5.9%,漏播率为3.3%,合格粒距变异系数为15.64%。各项性能指标满足农艺要求。

超磁致伸缩旋转超声加工系统研究进展

旋转超声加工是集传统旋转机加工方式和超声振动于一体的新型特种加工方法,在加工硬脆材料时具有切削力小、切削效率高、工件表面质量高、刀具寿命增长等优势。超磁致伸缩旋转超声加工系统具有相同功率条件下伸缩系数大、能量密度高等优点,在大功率、大振幅研究方面的前景广阔,是目前广受关注的一种新型旋转超声系统。因此,总结了超磁致伸缩旋转超声加工系统的核心功能部件和关键设计技术,综述了当下的超磁致伸缩旋转超声加工系统振幅控制研究现状,并展望其未来发展趋势。

自带动力式秸秆还田联合作业机设计及试验

针对新疆地区小麦秸秆还田作业时,现有耕整设备集成化低、作业质量差、周期长、需配套大功率拖拉机等问题,设计了一种自带动力式秸秆还田联合作业机.分析了整机结构并计算了所需配套动力、牵引力大小、旋耕刀辊直径,利用EDEM离散元仿真软件,建立土壤-秸秆-旋耕刀辊仿真模型,对螺旋形排列刀辊秸秆还田率、平整度、碎土率进行分析,以刀辊转速、作业速度、旋耕深度为试验因素,以秸秆还田率、旋耕扭矩为评价指标,开展三因素三水平正交试验,对试验结果进行方差分析和二次回归拟合得到最优旋耕刀辊作业参数,采用田间试验对理论设计和仿真模型进行验证.该机具在刀辊转速为268 r/min、作业速度为0.85 m/s和旋耕深度为10.0 cm作业条件下,碎土率为90.77%、秸秆还田率为91.38%、地表平整度为1.04 cm.结果表明:所设计的自带动力式秸秆还田联合作业机,一次作业可实现深松、细碎、秸秆还田、平整、镇压功能,使土壤达到待播状态,作业性能出色,各项性能指标均优于相关农艺要求和技术标准.

链箅机布料厚度和回转窑填充率自动化控制研究

目前,链箅机—回转窑是我国氧化球团生产的主要工艺,由于其连续、封闭的高温特性,生产过程中部分参数无法进行实时检测,会给工艺的自动化和运行改善带来困难,并会使生产线长期处于被动控制状态。鉴于链箅机布料厚度和回转窑填充率的自动化控制在实现球团自动化生产中起着重要的作用,本文以某企业典型的球团生产工艺为对象,基于现场运行数据和控制方法优选,建立链箅机布料厚度和回转窑填充率自动化控制方法。结果表明:采用基于生球堆比重K值计算的机速值可以与实际运行计算值较好地吻合,基于理论计算来获得填充率具有很好的参考意义,为实现7%~8%填充率的稳定运行,给料速率和转速之比值需控制在1.27~1.45。研究结果可为球团生产的自动化控制提供指导和借鉴。