复合型超声马达纵-扭振动固有频率简并研究

纵、扭振动固有频率简并是提高纵-扭复合型超声马达输出力矩的关键问题。然而同一弹性体内的纵振固有频率远高于扭振固有频率．目前对两种振动固有频率的简并缺乏深入的理论研究。纵一扭复合型超声马达振动分析模型都基于一维理论。在此提出了一种纵、扭振动固有频率简并的新方法。通过将纵一扭复合型超声马达设计成双定子对称结构．在定子上附加一个调整环改变定子的力学边界条件。实现纵、扭振动同频共振。应用Hamilton原理建立了考虑泊松效应的定子纵、扭振动理论模型，分析了定子的纵振与扭振第一阶固有频率随调整环质量和位置的变化规律，通过优化马达的几何结构参数获得了纵振与扭振的同频谐振点。     

纵-扭复合超声振动加工系统设计及频率简并研究

纵-扭复合超声振动加工技术在硬脆性材料的加工中受到越来越多的重视,针对该种需求,设计了一种纵-扭复合超声振动加工系统,基于有限元方法对该类系统普遍存在的频率简并问题进行了研究。利用数值解析方法设计出超声换能器和超声变幅杆,之后在变幅杆上做出螺旋槽,一部分纵向振动转换为扭转振动;以目标频率附近的纵、扭谐振频率尽量接近为原则,利用有限元软件分析系统的结构参数对纵、扭谐振频率的影响规律,实现频率简并;在此基础上对系统进行模态分析和瞬态动力学分析,结果表明系统可以实现纵-扭复合超声振动,验证了此种频率简并方法的有效性和实用性。     

径向-扭转振动复合型超声波电机的理论与实验研究

纵扭复合型超声波电机比其他超声波电机更具低速大力矩的特点,可以直接驱动负载,适合航空航天领域的应用.不过由于纵、扭振动在定子中的传播速度不一样,其纵、扭两相谐振频率的调谐一直是个难题.提出一种新型的中空结构的径向-扭转振动复合型超声波电机,采用一对纵振压电陶瓷和一对扭振压电陶瓷的组合方式,利用了径向一阶振动模态和扭振一阶振动模态,并通过电机定子的中空结构和尺寸的调整,使径向和扭转两相基频一致.首先从理论上分析了此方案的可行性,即提出了两相调谐的方法,并对以前的模型加以改进,然后根据理论分析制作了Φ60 mm的样机,经过试验,发现其性能满足设计要求,样机的最高转速为40 r/min,堵转力矩为3.2 N·m.研制的超声波电机较其他电机具有轴向尺寸小和重量轻等特点,可以减小质量40%.     

超声驻波马达耦合振子研究

Ｆ４超声驻波马达耦合振子研究彭军宇，周铁英（清华大学物理系北京·１０００８４）１９８５年Ｋｕｍａｄａ提出一种纵弯扭耦合超声驻波马达，该马达定子是由一个单梁纵弯扭耦合振子及与其相匹配的朗之万型换能器组成，文章没给计算方法。１９９３年我们用有限元方法计算...     

新型纵扭压电电机接触模型研究

提出一种新型贴片式纵扭压电电机,包含定子,转子和预压力系统等。电机定子经过特殊的开槽处理形成多振子结构,振子由金属基体和粘贴在其外表面的压电陶瓷构成,益于简化电机结构。通过合理的参数调整,使定子的一阶纵振模态和二阶扭转模态频率尽可能相同,并且振子均工作在共振状态,提高了电机效率。为评估设计电机的整体性能,建立了定子和转子的有限元接触模型,并对电机的接触特性进行分析研究。通过接触静态和瞬态求解,得到空载情况下接触区的压力分布、接触状态及滑动距离等参数,同时得到电机的转速变化曲线和输出性能等。分析结果表明该纵扭电机为多面接触,接触压力不存在局部高度集中的情况,且接触区域存在滑动。最后,根据设计的电机参数,加工原理样机,对理论分析进行实验验证。     

A1 功率超声发展近况和展望

Ａ１功率超声发展近况和展望林仲茂（中国科学院声学院研究所北京·１０００８０）近１０年来大功率超声的产生、基本效应和技术应用的研究有较大的进展。大功率超声换能器除常用的纵振模式外，发展了扭转和弯曲振动模式以及纵扭、纵弯等复合振动模式换能器，扩展了新的应...     

纵-扭复合超声对滚齿面强化机理及表面特性研究

为了强化齿面,提高齿轮表面的使役性能,使用一种新的纵-扭复合强化加工方法对齿轮进行强化。首先,基于赫兹接触理论和齿轮啮合理论,建立了纵-扭超声滚压齿面等效应力的理论模型;其次采用有限元仿真技术对该加工方式进行了模拟;最后利用已经搭建好的试验平台进行了一系列的纵-扭超声对滚齿面强化试验。通过对比仿真与理论结果对比,施加纵-扭超声后可以有效的提高接触应力,中有无超声振动接触应力提高约1.7倍～2倍,致使齿轮表面材料发生屈服进而完成。试验结果进一步表明纵-扭超声滚强化压改善了齿面的表面特性。当施加纵-扭复合超声振动时,齿面残余应力随阻尼力矩增大而增加,沿齿廓方向残余应力呈现先增大后减小趋势,在节圆处残余应力值最大。齿面的显微硬度HV_1.0数值沿齿廓呈现时变特性,超声滚压强化加工可以改善齿面表面形貌。与传统滚压相比,超声滚压强化后表面峰谷间距加宽,粗糙度降幅可达45%～55%。因此,纵-扭超声对滚强化加工可以实现齿面强化、改善齿面特性,提高残余压应力和显微硬度、降低表面粗糙度并提高齿面质量。     

U型变截面薄板面内复合模态驱动的直线超声电机

提出一种U型变截面薄板结构驱动的压电直线超声电机,选定U板两纵杆的一阶反对称纵振和二阶对称弯振为工作模态。阐释了电机驱动机理,推导了定子驱动端椭圆运动轨迹;基于纵、弯工作模态频率一致性模型,优化了电机结构尺寸;通过谐响应分析及激光测振试验,证实了定子工作模态的存在及其纯正性;设计出电机装配结构,制作出其原型样机;构建电机驱动控制平台,驱动电机运转,验证电机原理的可行性。通过速度特性试验发现:当驱动频率为78.11 kHz且电压幅值为240 V时,电机最大运动速度可达125.6 mm/s。     

基于梳状扇形孔周期性结构的纵-扭复合模态超声振动系统

纵-扭超声振动系统可以提高加工效率与精度、增加表面强度,因而日益受到青睐,但是现有的纵-扭振动系统存在扭转分量较小,转化效率低等问题,基于此,论文对基于周期性结构的复合模态超声振动系统进行了研究,通过有限元仿真对复合模态周期性结构换能器的振动模态、谐振频率等特性进行分析验证。研究结果表明,两维梳状扇形孔周期和斜槽结构,可以增大纵、扭振振幅,位移旋度和剪切应力以及法向应力等,从而提高纵-扭转化能力。     

单激励纵扭复合超声铣削系统研究

针对切削、焊接过程中超声复合振动能获得较高加工质量、效率及有助于延长刀具使用寿命,研究分析纵扭复合超声铣削系统运动特性及切削轨迹特征;基于斜梁振动原理,提出加工工艺简单、制造成本低的斜梁式超声变幅杆,并利用有限元软件ANSYS进行结构动力学分析, 证实通过单向激励可产生纵扭复合振动;应用研制的纵扭复合超声振动铣削系统对碳纤维复合材料进行切削试验,获得较好加工效果,从而验证理论分析与数值模拟结果的正确性。     

Piezoelectric ultrasonic motor using longitudinal-torsional composite resonance vibration

A piezoelectric ultrasonic motor, which uses longitudinal and torsional composite vibration, is examined in order to obtain high torque characteristics with small diameter. Piezoelectric ceramic elements, oscillating in both longitudinal and torsional modes, respectively, are used as piezoelectric stiffened modes having high electromechanical coupling factors k(33) and k(15), respectively. It is found that the resonant frequencies for longitudinal mode and torsional mode could coincide with each other in the ultrasonic motor, according to finite element method analysis and experimental measurement. The motor operating in both resonant vibrations indicated good performance. The 20-mm diameter motor exhibited 4 kgfcm maximum torque, 450 r/min maximum rotational speed, 40% maximum efficiency, and quick responsiveness, within 2.5 ms.     

Development of a radial-torsional vibration hybrid type ultrasonic motor with a hollow and short cylindrical structure

A longitudinal-torsional hybrid-type ultrasonic motor has larger torque and lower revolution speed compared with other kinds of ultrasonic motors. It drives devices directly and precisely, so it is adaptable to many fields, especially aeronautics and astronautics, as a servo actuator. Due to the different sound propagation speeds of longitudinal and torsional vibrations in the stator, it is difficult to match resonant frequencies of longitudinal and torsional vibrations. In this paper, a new radial-torsional vibration hybrid-type ultrasonic motor is put forward, which utilizes longitudinal vibration derived from radial vibration by the Poisson effect. The short, hollow cylindrical structure easily makes resonant frequencies of first-order radial and torsional vibrations into degeneracy. First, the new structure of the motor is presented. Second, the principle of matching the resonant frequencies is developed, and the motor geometry is optimized by ANSYS software. Finally, a 60-mm diameter prototype is fabricated, which performs well. The no-load velocity and maximum torque are 25 r/min and 5 N·m, respectively. This kind of motor is small, light, and noiseless.     

Improvement of the longitudinal vibration system for the hybrid transducer ultrasonic motor

This paper presents a symmetric hybrid transducer ultrasonic motor designed to produce large longitudinal vibration stress in the rotor/stator contact interface for high-torque operation. The nodal plane of the longitudinal vibration mode was adjusted to match the rotor/stator contact interface, and the piezoelectric ceramic disks for the longitudinal vibration were installed at the nodal plane of the longitudinal vibration mode for effective excitation. An experimental motor, 20 mm in diameter, using the first torsional vibration mode and the second longitudinal vibration mode was manufactured. A maximum torque of 0.8 N.m was achieved in the prototype, an improvement over previous versions.     

Sandwiched piezoelectric ultrasonic transducers oflongitudinal-torsional compound vibrational modes

Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound vibrational modes were studied. The transducers consist of coaxially segmented, longitudinally and tangentially polarized piezoelectric ceramic rings, a back metal cylinder, and a front exponential solid metal horn. Based on the plane-wave approximation, the equivalent circuits of the longitudinal and torsional vibrations in the sandwiched transducer were obtained and the resonance frequency equations of the transducer in longitudinal and torsional vibrations were derived. By means of choosing the radius decay coefficient of the front exponential horn, the longitudinal and torsional vibrations are made to resonate at the same frequency in the transducer. Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound modes were designed and fabricated according to the frequency equations. It is demonstrated that the measured resonance frequencies of the transducers are in good agreement with the theoretical results, and the measured resonance frequencies of the transducers in longitudinal and torsional vibration modes are also in good agreement with each other. Theoretical and experimental results show that this kind of transducer can be used in ultrasonic welding, ultrasonic machining, ultrasonic motors, and other ultrasonic applications which need large displacement amplitudes     

A U-shaped linear ultrasonic motor using longitudinal vibration transducers with double feet

A U-shaped linear ultrasonic motor using longitudinal vibration transducers with double feet was proposed in this paper. The proposed motor contains a horizontal transducer and two vertical transducers. The horizontal transducer includes two exponential shape horns located at the leading ends, and each vertical transducer contains one exponential shape horn. The horns of the horizontal transducer and the vertical transducer intersect at the tip ends where the driving feet are located. Longitudinal vibrations are superimposed in the motor and generate elliptical motions at the driving feet. The two vibration modes of the motor are discussed, and the motion trajectories of driving feet are deduced. By adjusting the structural parameters, the resonance frequencies of two vibration modes were degenerated. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 854 mm/s and maximum thrust force of 40 N at a voltage of 200 V(rms).     

Numerical analysis of the symmetric hybrid transducer ultrasonicmotor

In this paper, operation of a symmetric hybrid transducer ultrasonic motor with output produced by two rotors connected together via a drive shaft is numerically analyzed and compared with the traditional asymmetric hybrid transducer motor design that produces its output from only one rotor. A one-dimensional finite element model for torsional vibration in the stator and a Coulomb friction model for rotor/stator contact associated with the longitudinal vibration of the motor are introduced. The calculation results demonstrate that the symmetric design is capable of performance comparable with the traditional asymmetric design when an optimum static spring force in the rotor/stator contact interface is applied during operation     

Ultrasonic motors using piezoelectric ceramic multimode vibrators

The development is reported of an ultrasonic motor using piezoelectric ceramic multimode vibrators consisting of circular or annular plates in which degenerate horizontal vibration modes of the same or different form are used. Two orthogonal nonaxisymmetric vibration modes were used in the same-form case, and the combination of a nonaxisymmetric vibration mode and a radial vibration mode was used in the different-forms case. Some details of the motor design and its experimental characteristics are presented. The ultrasonic motor presented here has a special advantage in its thin construction.