Targeted suppression of vibration in deep hole drilling using magneto-rheological fluid damper

Under the concept of precision or targeted vibration suppression, a novel approach is developed to reduce the vibration of drilling tool system in deep-hole drilling process. The concept is to suppress the dominant vibration upon its emergence by variable damping or to force the harmful vibration morph into less harmful by different damper position. A magneto-rheological (MR) fluid damper is designed with adjustable damping capability to counteract emerging vibration. A series of experimental investigations are carried out on the BTA deep hole drilling process. The experimental results show that the adjustable MR damping brings down the vibration in all applications with different suppression effect. A relative optimal suppression can always be found. The suppressed vibration experiences a frequency shift which sheds light on the possible avoidance of matching of unwelcome frequency. Different damper locations have different but consistent suppression results which foresee a possibility of forcing the mode of vibration into less harmful one. A potential precision or targeted suppression of vibration upon its emergence is thus possible.     

电永磁夹紧方法及其影响因素

介绍了一种可用于夹紧或吸附工件的电永磁磁极结构,及其充磁、退磁的工作原理。对电永磁磁极进行了建模和有限元分析,计算了磁极的磁吸附力。模拟分析了磁极在充磁和退磁后的磁场分布情况,以及铷铁硼磁体、铝镍钴磁钢等的磁感应强度。分析了影响磁场强度的主要因素,并给出设计参数的选取方法或建议。有限元计算得到的磁吸附力与实验测试数据相吻合,表明,采用电永磁建立的吸盘可以满足压力机上的模具夹紧力要求。     

MRF和MRE磁流变夹层梁振动控制性能测试分析

分别设计了中间层结构为磁流变液(MRF)和磁流变弹性体(MRE)的两种磁流变夹层梁结构;搭建振动响应性能测试台,在外加局部磁场和不同磁场区域的条件下对MRF夹层梁和MRE夹层梁的固有频率和动态响应特性进行了测试及对比分析。实验结果表明,随着外加局部磁场强度的增大,MRF和MRE夹层梁的固有频率均呈下降趋势;随着磁场区域从夹层梁的固定端移动到自由端的过程中,MRF和MRE夹层梁的固有频率同样呈趋势下降;且MRE夹层梁的固有频率下降幅度比MRF夹层梁的要大。     

滚筒飞剪机剪刃侧隙自动调节装置

滚筒机构飞剪机是高速连轧机组中的关键设备,其剪刃侧隙对剪切断面的质量、调节精度起着重要的作用.本文介绍了滚筒机构飞剪机剪刃侧隙自动调节装置的结构设计、计算方法,并给出了相关数据.该装置用于梅钢1420 mm飞剪机.     

一种新型减振器自动焊夹紧装置的设计

在汽车减振器贮油缸总成的批量生产中,要实现总成的自动化焊接,定位夹紧装置是非常重要的.为此,笔者在原有成熟技术基础上研制了一种新型定位夹紧装置,它不但适用于精轧管贮油缸总成的焊接,而且适用于焊管贮油缸总成的焊接,适用范围更大.本夹具装卸工件方便,保证了焊缝质量、降低了成本、提高了生产效率.     

Vibration suppression of boring bar by piezoelectric actuators and LR circuit

This paper presents the vibration suppression of a boring bar using piezoelectric actuators installed in the boring bar, and an inductor-resister (LR) circuit, which acts as a mechanical dynamic absorber. The frequency response function of the compliance was designed so that its real part is constrained to suppress regenerative chatter. The designed boring bar with an optimally tuned LR circuit was set on a lathe to evaluate its dynamic characteristic, and it was found that the chatter vibration was successfully suppressed in the cutting test.     

冷轧带钢切边圆盘剪装置的优化与改进

针对冷轧带钢切边后产生的边部梗压印缺陷,结合切边圆盘剪的剪切原理,设计了一种圆盘剪复合衬套,其采用100Cr钢质内圈和MC尼龙外圈复合结构组成,取代原纯钢质衬套,使圆盘剪在剪切带钢过程中由钢性接触转变为弹性接触,从而避免了带钢边部梗压印缺陷的产生,提高了切边质量与剪切里程数,降低了圆盘剪备件成本,提高了生产效率。     

螺旋阻尼器的分析与应用

介绍了一种应用液压控制油路的螺旋阻尼带。分析了三角形过流断面的螺旋阻尼器的特点及主要参数的近似计算公式,将新的螺旋阻尼器应用于抽油杆检测台液压系统的压力继电器的控制油路中,起到了良好的阻尼缓冲作用,避免了由压力冲击引起的压力继电器误动作。     

基于自适应滤波的超声杂波抑制方法

在超声衍射时差(time of flight diffraction,TOFD)法检测获取的回波中,作为固定存在的侧向直通波信号会导致近表面缺陷信号不易于识别. 针对这一问题,提出一种基于自适应滤波技术的杂波信号抑制方法. 该方法通过迭代滤波器自身参数,调节参考信号以满足待处理回波中杂波的时基抖动变化要求,并予以去除,从而分离出与其混叠的近表面缺陷信号. 阐明了基于自适应滤波技术的杂波信号抑制原理,并利用所提方法对计算机仿真信号及人工缺陷检测回波进行了杂波抑制处理. 结果表明,所提方法可有效滤除超声TOFD法检测回波中具有时基抖动特性的杂波信号,并提取近表面缺陷信号.     

Tool edge honing using shear jamming abrasive media

Nature is replete with fascinating landscapes sculpted through interactions with moving fluids. Drawing inspiration from such, this research investigated intriguing mechanisms underlying the novel application of abrasive non-Newtonian media for rounding sharp edges of cutting tools. Through appropriate deformation, these media may be forced to correspond to rapid and reversible variations in viscosity that span several orders of magnitude, which render them particularly suited to this application. The innovative process is demonstrated to be uniquely capable of honing tools of a complex macrogeometry, generating edges that are symmetric/asymmetric and those that comprise a gradient in microgeometry along the edge length.     

磁流变阻尼器阻尼力建模及实验分析

结合理论分析与实验数据,提出了关于磁流变液的非线性正弦曲线粘滞环阻尼力模型,并给出了模型中参数的确定方法。该模型能较好地反映磁流变液的滞回特性,与自行设计的阻尼器的实验数据有较高的拟合精度。该力学模型方便计算与控制研究,有较高的实用价值。     

Milling force prediction using a dynamic shear length model

Modelling of cutting forces in milling is often needed in machining automation. In this paper, a new method for the determination of the cutting forces in face milling is presented, which applies a predictive machining theory originally developed for orthogonal cutting to milling operations, with a dynamic shear length model developed and incorporated. The proposed dynamic shear length model is developed based on the analysis for the true tooth trajectories of a milling cutter, taking into account of the characteristic wavy surface effects in milling. The prediction for the cutting forces is carried out at each step of the angular increment of cutter rotation from input data of fundamental workpiece material properties, tool geometry and cutting conditions. Cutting forces at a cutter tooth can be predicted once the shear angle, shear length, shear plane area, and the shear flow stress along the shear length have been determined. The milling force prediction using the dynamic shear length model is verified through milling experimental tests. The sensitivity of the difference between the static and dynamic shear length models with respect to the feed per tooth and the cutter diameter is discussed.     

Organic light-emitting device using new distyrylarylene host materials

Novel distyrylarylene-based blue host materials, 4,4′-bis(1,2-diphenylvinyl)-p-terphenyl (2), 4,4′-bis[1-phenyl-2-(p-tolyl)vinyl]-p-terphenyl (3) and 4,4′-bis[1-phenyl-2-(4,4′-biphenyl)vinyl]-p-terphenyl (4) were successfully synthesized using 4,4′-bisbenzoyl-p-terphenyl (1) through Wittig–Hornor reaction and a blue organic light-emitting diode (OLED) was made from them. The structure of the blue device is ITO/DNTPD/NPB/Host:DSA-Ph/Alq₃/Al-LiF. Here, NPB is used as a hole transport layer, DNTPD as the hole injection layer, DSA-Ph as the blue dopant, Alq₃ as the electron transport layer and Al as the cathode. The blue device doped with 5%-DSA-Ph shows a blue EL spectrum at 463 nm and a high efficiency of 4.14–5.13 cd/A.     

Weld defect detection using PPM EMAT generated shear horizontal ultrasound

Austenitic welds are inspected using PPM EMAT generated shear horizontal (SH) waves. Results are compared to measurements taken using a 1D piezoelectric phased array using the total focusing method (TFM). For the first time there is clear experimental evidence of the SH wave method demonstrating higher sensitivity to defect detection. SH waves suffer less beam steering in a weld than either compression or SV waves, which can miss defects due to weld microstructure anisotropy and attenuation. All defects were identified from every side of the weld/plate using the SH waves, but this was not possible using the piezoelectric transducer.     

Damping characteristics of an impact damper and its application

In this stuffy, in order to improve the damping capability of long, thin cutting tools, such as boring tools or drills, an impact damper with the following features was developed: small and simple in construction; easy to mount on the main vibratory systems; and no need to adjust parameters of an impact damper to the vibratory characteristics of the main vibratory systems. Using this impact damper, the characteristics of the impact damper were investigated in detail when the main vibratory system was vibrated in the direction of gravity and perpendicular to it. Furthermore, application of the impact damper to improve the damping capability of drills was attempted.     

Thermomechanical treatment of the elinvar alloy 44NKhMT using plain shear

Conclusions To increase the hardness of products with large cross sections (elastic sensitive elements, parts of measuring apparatus) made of alloy 44NKhMT, while at the same time reducing the temperature coefficient of the modulus of elasticity (to Y_E 9·10^-6 deg^-1), thermomechanical treatment using plain shear strain may be recommended.Physicotechnical Institute, Academy of Sciences of the BSSR; Bardin Central Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 30–33, October, 1982.     

Vibration monitoring of high speed spindles using spectral analysis techniques

A significant source of noise and vibration in precision high speed machine tool spindles is bearing induced vibration, which is caused by inherent geometrical characteristics, as well as out-of-balance assembly and interactions between rolling mating members with surface irregularities. The multitude of causes often makes a diagnostic approach quite arduous, particularly due to insufficient information obtained from frequency domain analysis alone. Furthermore, the averaging nature of Fourier analysis and its poor frequency resolution make the task in complex vibration spectra more difficult. The paper presents a new approach in use of auto-correlation analysis with good frequency resolution, combined with windowing capability to isolate significant causes for subsequent remedial actions. The method is applied to a routing spindle with special reference to primary induced bearing frequencies.     

Numerical analysis of shear deformation localization using a double-variable damage model

A double-variable damage model was introduced into the constitutive equations to demonstrate the effect of the material damage for the isotropic elastic, hardening, and damage states, and for the isothermal process. The shear damage variable D _s and the bulk damage variable D _b may be, respectively, used to describe the effect of shear damage and bulk damage for material properties without the superfluous constraint, D _b=D _s, that is found in the single-variable damage model. The double-variable damage model was implemented to form the finite element code for analyzing the effect of shear damage and bulk damage. In this article, two numerical simulation examples were completed to model the whole process of initiation and propagation of shear bands in an aluminum alloy. The numerical computational results are coincident with the experimental results.     

采用热焓平衡旋转磁场装置制备半固态浆料

在旋转磁场驱动金属液高速运动过程中,应用循环冷却水和金属液进行热交换控制金属液的热焓平衡生产A356铝合金半固态浆料,然后分别进行金属型和砂型浇铸,并对浆料在冷却过程中每隔5 min淬火取样浆料的平均冷却速度约为3℃/min。结果表明:热焓平衡旋转磁场装置作用下的金属液温度降至液固两相区内,瞬间产生大量均匀分布在金属液内的初生相α(Al)晶核,采用该方法制备的半固态浆料浇铸的铸件的微观组织呈现等轴球晶形貌,610℃时淬火试样的初生相晶粒平均直径为29μm,同时在缓慢冷却程中初生相α(Al)晶粒趋向于圆整并粗化。     

Non-contact measurement of spindle stiffness by using magnetic loading device

The radial stiffness of a rotating spindle is investigated in this research. A magnetic loading device (magnet loader) that attracts a dummy tool attached to the spindle is developed for this investigation. The dummy tool is designed so that the eddy current generated at higher rotational speed is suppressed. The spindle stiffness was measured with the developed device and compared with the calculated value. From the measurement results, speed and thermal effects on the stiffness were clarified quantitatively.