直线式压电垂直驱动振动给料机设计

目的 为了满足现代电子工业领域中对微小电子元器件高速送料的需要,采用环形压电双晶片,设计一种直线式压电垂直驱动振动给料机。方法 首先对给料机结构进行设计,阐述其工作原理,通过对环形压电双晶片进行模态分析,确定双晶片工作振型。然后利用小挠度的弹性薄板理论,推导压电双晶片输出力的表达式,利用Matlab软件,探究压电陶瓷和基板的厚度与出力系数的关系,以及压电陶瓷和基板的弹性模量与出力系数的关系。最后制作振动给料机样机,并对其进行实验测试。结果 测试结果表明,系统有效工作频率为184～190 Hz,当驱动电源电压为220 V,频率186.8 Hz时,对3.2 mm×2.8 mm的发光二极管(LED)给料速度可达到22.6个/s,比市场上同型号的矩形压电双晶片驱动给料机速度提升了14.7%。结论 在精密电子元件高速输送的自动化包装或自动化检测线上具有良好的应用前景。     

含金属芯压电纤维的纵向振动研究

建立了悬臂杆结构含金属性芯电纤维的纵向振动模型和动态测试模型。基于第一类压电方程,推导了外加简谐激励电压时,悬臂杆结构含金属芯压电纤维的等效纵向外力;基于纵向振动理论,推导出纵向振动模型;并由电位移,得到表面电荷、电流、导纳,建立了动态测试模型,通过测量共振频率fr、反共振频fa率和低频电容,计算出压电纤维的几个主要参数：弹性柔顺系数 、机电耦合系数 、介电常数 和压电常数 。详细叙述了纵向振动模型和动态测试模型的建立过程,并给出了具体的测试方法,提供了一个实际试样的测试结果。测试结果表明,根据纵向振动模型所建立的动态测试方法可以快速、准确地测量含金属芯压电纤维的主要参数。     

用于超声电机的压电陶瓷的探讨

在测试了国外超声电机用压电陶瓷晶片的性能以后,提出超声电机用压电晶片必须具备五高一低的特性,并制备出适用的压电晶片,经过多种振动模式超声电机的实际试用达到良好的效果。并进一步讨论了超声电机用陶瓷晶片深入研究的方向。     

微振动输送中圆盘型压电振子的动力学分析

目的研究压电陶瓷振动给料器的双晶片压电振子,求出其力学表达式,为振动给料器的双压电晶片的优化设计奠定理论基础。方法以螺旋式压电振动给料器的圆盘型压电振子为例,对圆盘型压电双晶片进行动力学分析,建立振动模型及动力学方程,对激振力进行求解。结果运用Rayleigh-Ritz法推导出在简支边界条件下,双压电晶片振子的弯曲振动的共振频率以及激振力表达式,得出最大误差出现在160 V处,理论计算与实验验证数据的误差为10%左右,有限元分析与实验验证数据的误差为5%左右。结论通过实验可以看出在实际应用中,要综合考虑其电压输入与压电陶瓷层的变形程度,选择最佳的电能输入,才能使压电双晶片获得最大的激励位移。     

大位移压电陶瓷驱动器的设计与试验

针对大位移压电陶瓷驱动器,研究了压电陶瓷双晶片的驱动效能。基于压电陶瓷材料的逆压电效应,应用压电陶瓷双晶片在机械自由、电学短路状态下,一片加正向电压缩短另一片加反向电压伸长共同作用产生弯曲变形,通过组合设计将压电陶瓷双晶片的弯曲变形位移叠加起来,实现了压电陶瓷驱动器的大位移输出。在相同电压的条件下,此压电陶瓷驱动器的输出位移量比叠层驱动器有较大的增加,达200μm,结构尺寸也大大减小。该驱动器不需要位移放大机构,可直接应用于有大位移要求的机构驱动。     

新型压电直线式振动送料器设计

目的为了满足现代工业领域中对轻、薄、小产品平稳输送的要求,设计一种利用压电双晶片振子惯性力作为驱动源的新型直线式振动送料器。方法在对振动送料器的工作原理进行分析的基础上,建立压电振子动力学模型,利用Matlab软件分析振子长度和质量对冲击力与变形量的影响,研制送料器样机并进行性能测试。结果当振动频率为209.5～214.5Hz时,送料器具备输送物料的能力;当系统共振时,输送速度最快,随着电压的增加,送料速度呈线性关系增加。结论与同型号的电磁振动送料器相比,研制的压电直线式振动送料器消耗电流仅为其14%,工作噪音下降了17 dB。与同型号日本压电送料器相比,输送速度提高了10%。     

准静态法测量纵向压电常数及其校准

纵向压电应变常数是压电材料的关键参数之一,准静态法是最常用的压电常数测量方法,而不同准静态压电测量仪的测试结果常存在一定差异.基于动态力传感器建立了可直接溯源的准静态法测量系统,研究准静态法压电常数测量的影响因素,包括预紧力、交变大小和电极形状等.PZT4和PZT5的测试结果表明:预紧力需达到10 N,交变力超过0.1...     

PZT含量对PZT-PZN-PNN压电陶瓷材料电性能的影响

采用传统固相法制备了xPb（Zr0.52Ti0.48）O3-（1-x）{Pb（Zn1/3Nb2/3）O3-Pb（Ni1/3Nb2/3）O3}（简称PZT-PZN-PNN）四元系压电陶瓷，研究了不同PZT含量对PZT-PZN-PNN陶瓷的相结构、显微结构、压电性能和介电性能的影响。结果表明：材料的压电常数（d33）、机电耦合系数（％）和介电常数（曲随着PZT含量的增加先增大，后减小，当PZT含量为0.83时，其值达到最大值；随着PZT含量的增加，材料的机械品质因数（Qm）逐渐增大，谐振电阻僻（Rf）和介电损耗（tanδ）逐渐减小。当PZT含量为0.83时，四元系PZT-PZN-PNN压电陶瓷在较低的烧结温度（1000℃）下烧结，其主要的电性能参数如下：d33=477pC/N，Kp=0.71，Qm=98，εf=2228，tanδ=0.0070，Tc=325℃，根据双晶片对压电陶瓷材料的性能要求，该纽份可作为纺织机械中选针器用压电双晶片的侯选材料。     

排列–浇铸法制备柔性压电纤维复合驱动器

设计了该压电纤维复合驱动器的结构,包括叉指电极板、粘结层和压电纤维复合层三部分。采用排列–浇铸法制备了柔性的层状压电纤维复合驱动器。测试了铌锌锆钛酸铅(PZN-PZT)陶瓷的电学性能及力学性能,理论推导了压电纤维复合材料的压电性能,并采用基于LabVIEW的动态应变系统测试了驱动器的应变性能。结果表明,PZN-PZT陶瓷的压电常数d33为520 pC/N,居里温度Tc为320℃,弹性柔顺系数s33为20.5×10–12m2/N。压电纤维复合材料的理论压电常数d33为509 pC/N,d31为–156 pC/N。在300 V正弦交变电压作用下,驱动器可以产生100με的纵向应变和58με的横向应变,即纵横向伸缩分别可达3.6和1.7μm,说明该驱动器具有较高的机电性能。     

逆压电效应的压电常数和压电陶瓷微位移驱动器

本文介绍了由过压电效应的应变-电场曲线测得弱场和强场下的压电常数d₃₃、d₃₁．测量发现S～E曲线上呈现应变和压电系数突增的阈值场强E_b,用铁电陶瓷固有的90°畴转向对应变的贡献进行了分析和讨论．该方法与以往常用的正压电效应的压电常数测试相比,方便、简单,尤其对过压电效应的压电微位移驱动器应用更具有实际意义．     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.