Experimental Study on Entropy Features in Machining Vibrations of A Thin-Walled Tubular Workpiece

In machining processes,chatter vibrations are always regarded as one of the major limitations for production quality and efficiency.Accurate and timely monitoring of chatter is helpful to maintain stable machining operations.At present,most chatter monitoring methods are based on the energy level at specified chatter frequencies or frequency bands.However,the spectral features of chatter could change during machining operations due to complexity and time-varying dynamics of the physical machining process.The purpose of this paper is to investigate the time-varying chatter features in turning of thin-walled tubular workpieces from the perspective of entropy.The airborne acoustics was selected as the source of information for machining condition monitoring.First,corresponding to the distinguishing surface topographies relevant to machining conditions,the features of the sound signal emitted during turning of the thin-walled cylindrical workpieces were extracted using the spectral analysis and wavelet packet transform,respectively.It was shown that the dominant vibration frequency as well as the energy distribution could shift with the transition of the machining status.After that,two relative entropy indicators based on the spectrum and the wavelet packet energy were constructed to identify chattering events in turning of the thin-walled tubes.The experimental results demonstrate that the proposed indicators could accurately reflect the transition of machining conditions with high sensitivity and robustness in comparison with the traditional FFT-based methods.The achievement of this study lays the foundations of the online chatter monitoring and control technique for turning of the thin-walled tubular workpieces.

Torsional vibration analysis of lathe spindle system with unbalanced workpiece

For the purpose of analyzing the torsional vibration caused by the gravitational unbalance torque arisen in a spindle system when it is machining heavy work piece,a 10-DOF lumped parameter model was made for the machine tool spindle system with geared transmission.By using the elementary method and Runge-Kutta method in Matlab,the eigenvalue problem was solved and the pure torsional vibration responses were obtained and examined.The results show that the spindle system cannot operate in the desired constant rotating speed as far as the gravitational unbalance torque is engaged,so it may cause bad effect on machining accuracy.And the torsional vibration increases infinitely near the resonant frequencies,so the spindle system cannot operate normally during these spindle speed ranges.

Humanoid Based Intelligence Control Strategy of Plastic Cement Die Press Work-Piece Forming Process for Polymer Plastics

The plastic cement belongs to a sort of polymer material, the chemical composition is very complex, and the plastic cement work-piece is generally manufactured by die press forming. Aimed at being difficult to control in parameters of forming process, the paper explored the humanoid based intelligence control strategy. In the paper, it made the anatomy in control puzzle resulted in uncertainty such as chemical component of plastic cement etc., summarized up the characteristic of cybernetics in forming process, researched on the humanoid based intelligence control strategy, and constructed the control algorithm of forming process in plastic cement work-piece. Taking the process experiment of temperature and pressure control as an example, it validated the good dynamic and static control quality through simulation of control algorithm constructed in this paper. The experimental results show that the control algorithm explored in this paper is reasonably available.

背压扰动平衡盘对涡旋压缩机黏性内流压力影响研究

在变转速工况下,电动涡旋压缩机背压腔中润滑油产生的背压力无法准确平衡轴向气体力。针对这一问题,提出了一种带有扰动片的背压扰动平衡盘,研究了背压扰动平衡盘对涡旋压缩机黏性内流压力的影响。首先,对背压扰动平衡盘作用原理进行了分析,使用贝塞尔曲线构建了扰动片型线,对润滑油被扰动后的静压增量进行了公式推导,计算了扰动片出口安装角和扰动片数对润滑油静压的影响;然后,建立了含背压扰动平衡盘的背压腔模型,将流体域分为旋转域和静止域,采用旋转坐标系的方法进行了数值模拟,研究了背压腔内润滑油的压力场;最后,根据理论计算,模拟了润滑油在不同出口安装角和扰动片数下的润滑油静压,对润滑油静压与压缩机所需最佳背压进行了对比分析。研究结果表明:采用背压扰动平衡盘可以使润滑油静压增加21%,且静压增量随主轴转速的增加而增大,适当增大扰动片出口安装角可使润滑油静压增加0.032 MPa;对比最佳背压可知,扰动前润滑油静压与最佳背压相差26%,而合理设计扰动片后的润滑油静压与最佳背压相差仅为9%,极大改善了电动涡旋压缩机在变转速下的轴向平衡。

“数字泰勒主义”影响下的外卖平台“计件工资制”研究

对工业生产中“计件工资制”的研究表明,薪酬制度不仅从经济维度影响劳动者的行为,更是形塑劳动者从纯劳动力意识向纯劳动意识转变的重要机制,是劳动力过度商品化的重要基础。本文通过对外卖平台“计件制”中的派单、奖励、惩罚等规则的梳理,提出平台“计件工资制”虽然在形式上承继了工业生产“计件制”“多劳多得”的简单累积逻辑,但根本上已经变成了高投入、高回报和高风险的企业家式博弈,以及本质上的加速积累逻辑。同时,通过对骑手个体经营意识、过渡意识、自由意识、平等意识等被薪酬制度所形塑的企业家式劳动主观意识的呈现,进一步提出外卖平台薪酬制度的变迁意味着平台劳动中的“数字泰勒主义”并非工业劳动经典“泰勒制”的自然延续,而是具备了主客观方面的独特特征。

work on sth.与work at sth.

work on sth.与work at sth.的含义是不同的。一、work on sth.的意思主要有: 1.从事(某工作),致力于(做某事) 1)Green is working on(busy writing)a new novel. 2)He took out a piece of chalk and wrote his problem on theblackboard.Then started to work on it.

品管圈活动在中药饮片质量管理中的应用效果

目的探讨开展品管圈(QCC)活动在降低中药饮片质量变异率中的应用效果。方法选取2020年5月至2021年5月广东省英德市人民医院中药房采取常规管理期间102 kg中药饮片以及同期11名药房工作人员作为对照组;另选取2021年6月至2022年6月广东省英德市人民医院中药房采取QCC活动期间102 kg中药饮片以及同期11名药房工作人员作为观察组。比较两组中药饮片质量变异率、工作人员工作能力以及患者满意度。结果观察组中药饮片质量变异率低于对照组,差异有统计学意义(P<0.05);观察组干预后工作人员解决问题能力、工作积极性、团队凝聚力、沟通能力、责任感、自信心、品管手法和团队合作性评分均高于对照组,差异有统计学意义(P<0.05);观察组患者对工作人员工作效率、服务态度、安全管理、工作质量以及工作效果满意度评分均高于对照组,差异有统计学意义(P<0.05)。结论开展QCC活动可降低中药饮片质量变异率,有效保障中药饮片用药安全,促进工作人员工作能力提升,使患者对药房服务更加满意。

Study of Optimal Parameters of Improved 1RX Regenerator

In this article, researches on improvement of 1RX regenerator used in cleaning processes of cotton ginning enterprises were carried out. The effect of changing the parameters of the new working body—rubber-plate drum and machine inlet on the efficiency of cotton separation was studied in the research, and the maximum level of efficiency of separation was determined. In this paper work, the main factors affecting the efficient operation of the regenerator were identified, their value limits were determined, and research was conducted using the mathematical planning method. As a result, effective operation of the improved 1RX cotton regenerator was observed at the value of the given factors, that is, the separation efficiency was 99.5%, the cleaning efficiency was higher than 88.7%, and the amount of seed cotton in the waste was reduced lower than 2.5%.

Precision Work-piece Detection and Measurement Combining Top-down and Bottom-up Saliency

In this paper, a fast and accurate work-piece detection and measurement algorithm is proposed based on top-down feature extraction and bottom-up saliency estimation. Firstly, a top-down feature extraction method based on the prior knowledge of work- pieces is presented, in which the contour of a work-piece is chosen as the major feature and the corresponding template of the edges is created. Secondly, a bottom-up salient region estimation algorithm is proposed, where the image boundaries are labelled as background queries, and the salient region can be detected by computing contrast against image boundary. Finally, the calibration method for vision system with telecentric lens is discussed, and the dimensions of the work-pieces are measured. In addition, strategies such as image pyramids and a stopping criterion are adopted to speed-up the algorithm. An automatic system embedded with the proposed detection and measurement algorithm combining top-down and bottom-up saliency （DM-TBS） is designed to pick out defective work-pieces without any manual auxiliary. Experiments and results demonstrate the effectiveness of the proposed method.

电磁感应高温空气加热特性试验研究

将电磁感应加热技术应用到空气加热领域,研制新型高温空气加热装置。在电磁感应磁场中依靠加热装置内部感应加热件所产生的感应热对空气进行加热。在高温空气加热试验装置上,进行加热功率、空气流量、加热件初始温度对空气加热特性的影响规律的试验研究。结果表明:电磁感应高温空气加热装置能够快速方便地产生高温空气,空气终温可达900℃以上;通过改变电源功率或进入加热装置的空气流量,可以产生不同终温的高温空气。

FANUC弧焊机器人系统标定研究与实现

在多传感器信息应用的前提下,针对马鞍型焊缝工件首次提出了工件坐标系的三点标定方法.利用从机器人控制柜获取实际工件上的3个特殊点位置,通过VB编程完成了工件坐标系标定.在此基础上,采用FANUC公司的六点标定方法,对工具坐标系进行了标定,从而为机器人离线编程的进行提供了前提条件.试验表明,通过以上的系统标定,机器人的定位精度达到了±0.5 mm,满足了工厂的实用要求.

金属圆柱工件缺陷的光电检测

针对金属工件外观缺陷检测存在光学照明不均、检测缺陷种类繁多、检测系统识别率不高等问题,研究了检测金属圆柱工件缺陷的方法。分析了局部二元模式(LBP)与局部图像方差强度(LVAR)的基本原理,研究了两者在金属纹理表面缺陷检测中的具体实现方法。采用LBP反应局部图形空间纹理模式,LVAR突出图像强度对比信息,然后用LVAR计算结果作为权重值来调整LBP的局部纹理提取和度量结果,实现了金属圆柱工件的自动缺陷检测。实验中采用步进电机控制工件旋转,配合线阵相机采集圆柱工件的展开图像。实验结果显示,这种方法有效克服了金属材质光照不均的缺点,对大量缺陷种类具有较高的鲁棒性,其检出率高达95.1%,漏检率为0%,满足了工业检测要求。

淬火过程数值模拟技术的研究进展

淬火是使工件获得预期的组织和性能的一种重要热处理工艺。由于淬火试验存在高温作业、在线测量困难、成本高等问题,淬火过程的数值模拟成为目前淬火技术研究的重要手段。综述了淬火过程数值模拟技术的发展历程,分阶段地介绍了淬火过程中工件、冷却介质、工件和冷却介质耦合的数值模拟技术的研究现状,提出了今后一段时间内淬火过程数值模拟技术的发展方向。

方盒件拉深摩擦状况的分析与控制

摩擦状况是评定拉深成形难易甚至成功与否的重要指标之一 ,而法兰部分又是拉深时的主要变形区域。鉴于上述原因 ,本文通过探针法来获取各种情况下不同部位的摩擦系数 ,进而分析出方盒件的成形特点 ,并分析出各种工艺参数与材料参数对成形时摩擦的影响规律 ,以便在实际生产中能对摩擦状况进行控制。

面向工件随机到达的机床节能运行方法

为提高机床运行阶段的能量利用率,针对目前机床加工间隔节能方法缺乏考虑工件随机到达的现状,提出一种面向工件随机到达的机床节能运行方法。基于机床运行状态制定了一种机床在加工间隔中的节能运行策略,以计算机床在采用该节能运行策略后的一个加工间隔中所消耗的预期能量。通过对该预期能量的优化,实现对节能运行策略中机床运行参数的优化,得到节能运行方法。将该机床节能运行方法应用到具体实验中进行分析,比较使用节能运行方法前后机床在加工间隔中消耗的能量,结果显示,机床应用所提节能运行方法后能适应工件的随机到达,并提高其在加工间隔中的能量利用率。

一种基于SIFT特征匹配的工件识别方法

为了解决平移、旋转、缩放和部分遮挡等复杂环境下的工件图像匹配识别问题,给出了一种基于SIFT(尺度不变特征变换)特征匹配的工件识别算法。该算法采用SIFT特征作为匹配特征,引入欧氏距离作为图像匹配的相似性度量,并采用设定阈值的方法剔除误配点。实验结果表明,该算法能有效解决具有平移、旋转、缩放和部分遮挡等情况下的工件匹配识别问题。

基于二次阈值分割的方向倒脚匹配工件识别

为提高机器人在复杂背景下利用模板匹配对工件的识别率,提出基于二次阈值分割的方向倒脚匹配(orientation chamfer matching)方法。利用大津法对复杂背景的目标图像进行第一次图像阈值分割,使用迭代阈值法对目标图像进行第二次图像阈值分割,运用方向倒脚匹配的方法对工件目标进行识别。对选取的40张复杂背景下的工件图片进行测试与分析,工件的平均识别率达到72.75%,误检测降低到0.75%。实验结果表明,该改进算法与传统方向倒脚匹配相比性能有较大提升,在复杂背景下对工件识别有效可行。

一种新的二维CT扫描方式及其重建算法

介绍了一种二维CT扫描方式及其重建算法。它是一种利用近轴X光线,针对大型回转试件的二维CT检测方法。被扫描试件依次绕与探测器平行的多个旋转中心各旋转一周。在旋转过程中,射线源在周向均布的多个角位置发射射线,同时探测器接收射线并记录投影数据。同传统的二代CT相比,对一个具体例子的计算表明,它可以节约3/4的扫描时间。计算机仿真表明了这种扫描方式和重建算法的可行性。

加工工件位置和姿态的自动检测、识别与校正方法(英文)

加工工件在数控机床工作台上位置的精确确定是数控系统研究中必须仔细考虑的问题。以数控机床为对象 ,提出了一种对有定位基准平面或工艺基准平面类工件位置和姿态精确确定的新方法 ,并论述了测量所用传感器的工作原理和实验考核。该方法可实现将工件粗略安装在工作台的合适位置上 ,使用自行研制的高精度检测传感器和有效的算法进行加工工件位置和姿态的自动测量、识别和校正 ,而无需夹具的精确定位 ,而且在测量系统上设置有自动减速单元以提高测量效率。通过实验证明了该方法是正确的、可行的。