GH4169高温合金轴向超声振动钻削加工实验研究

针对GH4169高温合金材料钻削加工困难、表面质量和加工精度要求高等难题,基于在普通车床上实现超声振动钻削加工的思想,设计了一套轴向超声振动钻削加工系统。利用该系统对GH4169高温合金材料做了轴向超声振动钻削与普通钻削的对比实验。结果表明:在不同的转速和振幅下,轴向超声振动钻削相对于同一实验条件下的普通钻削,可明显提高孔的加工质量,且在切屑形态和孔表面形貌等方面均有较大改善。     

深孔超声轴向振动钻削装置的设计与研究

根据振动切削机理对超声振动钻削和普通钻削进行了分析和比较,设计出一种在摇臂钻床上加工小直径深孔的超声轴向振动钻削装置.并分析了超声振动钻削装置设计中的一些关键技术问题,为在摇臂钻床上加工小直径深孔提供了一种新的工艺方法.     

超声复合电加工振动参数检测控制与试验研究

利用高速、高精激光微位移传感器及高频数字示波器进行超声及其复合加工的振动参数(振幅与频率)在线测量,其结果具有高精度和实时性。设计了控制软件,为保持超声振动的稳定及复合电加工参数的在线实时调节与优化建立了基础条件,同时通过数学处理得到了超声振幅与超声激振电压之间的关系。利用分析与测试结果合理选择加工参数,对陶瓷、硬质合金等硬脆性难加工材料进行了超声及其复合电加工试验,超声振动系统工作稳定可靠,试验结果验证了超声及其复合电加工技术对硬脆难加工材料的加工优势。     

复合超声振动镗削声振系统的研究

超声振动加工在难加工材料方面的应用越来越广,而在镗削中的应用不多。声振系统性能的好坏直接影响到超声加工质量,而实验表明单激励振动仍不能满足不断提高的加工要求。针对超声镗削加工,设计一种实现纵扭复合振动的变幅杆,阐述了振型转换原理,进行了结构计算和运动分析,借助有限元分析软件ANSYS对模型进行模态分析、瞬态动力学分析和谐响应分析,为二维超声镗削声振系统的结构设计和性能优化提供了理论依据。     

超声加工技术的研究现状及其发展趋势

结合近年来超声加工技术的发展状况,综述了超声振动系统的研究进展和超声加工技术在深小孔加工、拉丝模及型腔模具研磨抛光、难加工材料的加工、超声振动切削、超声复合加工等方面的最新应用,并阐述了超声加工技术的发展趋势.     

轴向功率超声振动珩磨颤振的稳定性分析

功率超声振动珩磨颤振是影响零件加工表面质量的主要因素之一,其稳定性研究具有重要意义.利用解析法和作图法对建立的轴向超声振动珩磨非线性动力学模型分别从轴向和径向进行了稳定性分析,得出刚度非线性因素对轴向稳定性影响不明显,超声激振频率对轴向响应幅值有较大影响,推导出径向系统稳定性方程,得出加工参数与响应幅值的关系,对抑制颤振方法提供了理论基础.     

超声加工技术研究进展

超声加工技术依靠瞬时高频振动撞击对工件断续加工,具有极强切削能力的同时,具有较小的宏观切削力,主要用于硬脆材料的精密加工,能提高加工精度和表面质量。首先,阐明了超声加工技术的基本原理及其基本应用范围。其次,综述了超声辅助切削加工技术的研究进展,着重论述了超声辅助铣削净切削时间模型的建立以及模型正确性验证,总结了加工参数对刀具运动轨迹、工件表面质量的影响,阐明了椭圆振动切削能有效抑制切削颤振带来不利影响的原因;探讨了超声辅助磨削技术在加工非金属和金属材料时,对表面质量以及工件表面温度分布的影响;综述了超声辅助钻削技术的切削力和进给速度与普通钻削参数的比较。再者,介绍了超声波加工技术的新发展方向,包括三维椭圆超声振动切削技术、超声ELID复合磨削技术、超声EDM复合加工技术、超声辅助抛光的工作原理及最新研究趋势和能实现的试验效果。最后,总结了目前对超声加工技术及超声辅助或复合技术的研究。     

微小孔加工超声电火花系统设计

在难切削材料的微小孔电火花加工中,电火花机床的电极丝一般由机床电主轴端部引入导向套中定位,基于此设计一种通孔式超声系统。所设计的指数过渡阶梯形变幅杆能将两种单一形变幅杆的优势结合起来,且便于电极丝的放入。结合所购置的超声发生器和换能器将此变幅杆的谐振频率设计为43 kHz,大端面设计为20 mm,小端面设计为12 mm。计算其余参数后使用ANSYS进行有限元分析、参数优化,并对加工后的超声系统进行阻抗分析试验,再安装于电火花机床上对不同材料进行微孔加工,观测入口形貌。计算与试验表明：仿真优化后的超声系统的频率与实际频率相差很小,稳定性较高;添加超声加工微孔,不论是加工效率还是孔的表面形貌,都比普通电火花加工质量好。试验结果验证了该超声系统符合初始设计要求。     

夹心式换能器设计中节面位置的选择与分析

夹心式压电换能器是功率超声加工系统的重要组成部分,在其设计过程中,不同的节面位置选择会对换能器的尺寸和性能参数产生不同的影响,同时,对整个功率加工系统也产生影响.针对3种节面位置进行分析,得出其在换能器尺寸、前后振速比和有效机电耦合系数方面的3种特殊位置公式,并进行对比分析,为换能器设计初期进行节面位置选择提供了一定的依据.     

薄壁盘类零件超声振动车削实验研究

薄壁盘是典型的弱刚度轻量化零件,其壁厚很薄(最薄处仅0.3 mm),型面面积较大,故刚性较差。在切削过程中,切削力导致的型面变形是薄壁盘类零件加工的主要难题,传统加工方法很难得到高精度和高质量的产品。利用超声振动切削技术尝试进行弱刚度薄壁盘加工,在自行搭建的实验平台上对超声振动车削和普通车削加工薄壁盘进行对比实验。结果表明:与普通车削相比,超声振动车削可显著减小切削力和切削变形,大幅提高加工质量,同时具有断屑特性,是加工薄壁盘类零件的有效方法。     

Nd-Fe-B烧结永磁材料超声辅助磨削试验研究

对Nd-Fe-B烧结永磁材料普通磨削和径向超声振动辅助磨削的工艺进行了对比试验,系统分析了在两种工艺条件下磨削用量对法向磨削力的影响;深入研究了超声振动和磨粒切削的复合过程,指出超声振动形成的断续磨削机制是降低法向磨削力的主要原因.径向超声振动的辅加改善了磨削加工效果,在一定程度上避免了脆崩现象,保证了Nd-Fe-B烧结永磁材料加工表面的完整性.     

B样条曲线拟合在数控内孔曲线磨床加工中的应用

为了改善定子曲线(列表曲线)的平滑性及使曲线曲率变化更加均匀,从而使定子曲线径向速度、加速度变化率无突变,不产生激振,使机床加工出的定子轮廓误差更小、表面粗糙度更小,提出采用B样条曲线拟合法对列表曲线进行拟合后再加工的方法。在用QMK003数控内孔曲线磨床加工定子时,应用了上述方法,并测试加工后的定子,结果表明:泵的噪声降低,效率提高。说明该方法是可行的,具有很强的推广价值。     

Modeling the machining stability of a vertical milling machine under the influence of the preloaded linear guide

The prediction of machining stability is of great importance for the design of a machine tool capable of high-precision and high-speed machining. The machining performance is determined by the frequency characteristics of the machine tool structure and the dynamics of the cutting process, and can be expressed in terms of a stability lobe diagram. The aim of this study is to develop a finite element model to evaluate the dynamic characteristics and machining stability of a vertical milling system. Rolling interfaces with a contact stiffness defined by Hertz theory were used to couple the linear components and the machine structures in the finite element model. Using the model, the vibration mode that had a dominant influence on the dynamic stiffness and the machining stability was determined. The results of the finite element simulations reveal that linear guides with different preloads greatly affect the dynamic behavior and milling stability of the vertical column spindle head system. These results were validated by performing vibration and machining tests. We conclude that the proposed model can be used to accurately evaluate the dynamic performance of machine tool systems designed with various configurations and with different linear rolling components.     

Improvement strategy for machine tool vibration induced from the movement of a counterweight during machining process

The objective of this study is to propose and execute an improvement strategy for machine tool vibration induced from the movement of a counterweight balance system during the machining process. The elastic jump due to the effects of the inertia of a counterweight and of the potential energy released from the connected chain is investigated, firstly by using the dynamic analysis numerical software, Nastran, when the machine tool head makes a sudden stop during different motion types in the machining process. In turn, the vibration energy absorber, such as spring and damper, is assembled together in parallel manner, which is then connected to the counterweight in series, attempting to reduce the phenomenon of induced vibration to the utmost. The design and fabrication of a vibration reduction system for machine tool head during the machining process is performed based on the absorber parameters obtained from the simulation calculations. Milling experiment on aluminum alloy is undertaken in conjunction with various CNC cutting-path planning, such as moderate steps and vertical steps under different feed-rate cutting conditions. No concentric-strip-like waviness was detected on machined surface during the former cutting path. But such kinds of waviness marks left on the machined surface around the corner area between the subsequent steps are very obvious with the vertical-step path. This induced tool vibration phenomenon is remarkably improved through the strategies proposed and implemented in this study.     

旋转超声辅助加工装置及其工艺研究

基于传统超声振动理论,提出了一种新型旋转超声辅助加工装置。该装置将超声振动与负载匹配二者相结合,具备旋转超声辅助加工硬脆材料的能力。利用该装置对微波铁氧体材料进行旋转超声辅助钻削加工试验研究,验证了旋转超声辅助磨削可有效降低加工过程中的切削力。同时,在保证刀具和材料安全的前提下,探索了旋转超声辅助加工装置对加工效率的影响。     

某型镗铣床主轴系统结构设计

主轴系统是镗铣床的核心部件,合理地设计结构,能够提高主轴系统的刚性和切削性能,降低振动和噪声.通过对某型镗铣床主轴系统的设计阐述了镗铣类机床主轴系统设计的方法和原则,并以切削试验证明所设计的主轴系统具有良好性能.     

Active vibration control in palletised workholding system for milling

This paper presents the development implementation and testing of an active controlled palletised workholding system for milling operations. The traditional approach to controlling vibration in a machining system is to develop control systems for cutting tools or machine spindles as in the case of milling machines. This work is a deviation from the traditional approach and targets a workholding system for the control of unwanted vibration. Palletised workholding systems, due to their compact design, offer an opportunity to design active control systems that are economical and easier to implement in the case of milling machines. The active control system developed here is based on an adaptive filtering algorithm, the filtered X-LMS, and employs piezo-actuators for dynamic control force. The system has been tested experimentally to demonstrate the reduction in dynamic force due to vibration. Extensive testing has been carried out to validate the performance of the system in terms of parameters of practical importance such as improvement in surface finish and increase in tool life.     

工作液超声振动辅助电火花小孔加工装置设计与试验

电火花加工小孔存在电蚀产物排出效率低导致加工效率低、电蚀产物排除导致二次放电现象影响加工精度等问题,而超声振动在工作液中产生空化效应和泵吸作用,能大幅提高电火花的排屑和消电离能力,进而在很大程度上减少上述问题的发生。设计一套工作液超声振动辅助电火花小孔加工装置,主要包括主轴系统、微三维运动平台、超声振动工作液槽和数据采集系统,其中主轴系统包括NSK电主轴、引电结构、工具电极装夹结构,可以实现工具电极的高速旋转;基于LabVIEW开发了电火花小孔加工控制系统,主要包括初始化模块、粗定位模块、恒电压对刀模块、实时电压分段控制加工模块和实时显示模块。开展了工作液超声振动辅助电火花小孔加工试验研究,试验结果表明：随电火花加工电压的增加,工件材料去除率和电极损耗率都趋于增大。     

超声椭圆振动切削技术及装置应用研究现状及进展

首先,阐述了超声椭圆振动切削技术、原理及其装置特点,着重论述了装置各构成部分的特点及其主要应用类型与材料。其次,分析了国内外学者在双激励、单激励方式下实现纵弯、纵扭、双弯曲和弯扭等复合超声振动装置结构设计及其优化方面的研究成果与进展,并且比较了超声椭圆振动切削与传统加工在加工性能、工件表面质量和加工精度等方面的加工优势与适用范围,以及不同超声振动装置在各切削加工中所能获得的加工效果。最后,对超声椭圆振动切削装置的发展趋势进行了总结和展望,指出该装置发展将朝着结合能场的方向发展。     

A theoretical and experimental investigation into five-DOF dynamic characteristics of an aerostatic bearing spindle in ultra-precision diamond turning

In ultra-precision diamond turning (UPDT), spindle vibration has great influence on machining precision of high precision optical components. However, the spindle-vibration mechanism has not been fully understood. In this study, mathematical solutions for a proposed five-degree-of-freedom (FDOF) dynamic model of an aerostatic bearing spindle are derived to explore natural mechanisms of spindle vibration. Thus, the potential benefits of the solutions are to be applied for the prediction and optimization of the effects of spindle vibration on surface generation. Its dynamic characteristics possess three translational frequencies along the radial and axial directions, a spindle rotational frequency (SRF), and a pair of coupled tilting frequencies (CTFs) around the radial directions influenced the SRF. The theoretical results are identified by the frequency characteristics of thrust cutting forces, and the periodic, concentric, spiral, radial and two-fold patterns (PCSRPs) of the machined and simulated surface topographies, respectively.