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。     

金和田青玉超声波振动深孔钻削试验研究

基于和田玉特殊的物理性能,采用金刚砂钻头和高速钢麻花钻在附加超声波振动和不附加超声波振动的条件下进行了和田青玉的钻削试验,在加工工件的刀具损坏、出口毛刺、孔表面微观质量3个方面进行对比分析,超声振动波钻削能获得更好的加工质量和效率,并能减少刀具的磨损和破坏,为和田玉精密加工提供了一种新的深孔加工工艺方法。     

和田玉超声波振动深孔钻削特性分析

基于和田玉超声波振动深孔加工工作和结构原理,构建和田玉超声波振动深孔钻削模型;通过和田玉超声波振动深孔钻削模型分别建立和田玉超声波振动深孔钻削钻削厚度和钻削动力学模型,通过分析计算结果,钻头在一个圆周内的钻削过程中出现空钻现象,出现空钻现象与钻削进给量参数与振动的振幅有关系,钻削进给量小于振动的振幅就会出现空钻现象;振幅的损失量与超声振动钻削系统的刚度有密切关系;在保持阻尼不变的情况下,系统刚度值减小,则振幅损失增大。     

大孔径和田玉超声波振动深孔钻削系统设计

根据和田玉材料高硬度、高韧性的特点,设计一种大孔径内排屑超声波振动深孔钻削系统。重点介绍了加工系统主要部件钻头、振动系统的设计。研究了大孔径、内排屑方式超声波深孔振动钻削理论,为后期研究和田玉超声波深孔加工机制及其裂纹预防策略提供了理论依据。     

和田青玉超声波深孔高速钢麻花钻钻削试验研究

基于和田玉特殊的物理性能,采用直径为2、1.5、1 mm的高速钢麻花钻,在其主轴转速为700、1500、1800r/min;进给量为3μm/r和5μm/r的情况下;分别进行附加超声波振动和不附加超声波振动加工试验;在钻削加工过程刀具磨损,扩孔量、孔内表面粗糙度三个方面进行对比分析,超声振动波钻削能获得更好的加工质量和效率,并能减少钻头的磨损和破坏,为和田玉精密加工提供了一种新的深孔加工工艺方法。     

超声波椭圆振动装置设计及其振动特性控制

基于PZT-8陶瓷晶片的压电效应和超声波声学特性,设计制造了超声波换能器和变幅杆。根据椭圆轨迹形成机理,搭建了超声波椭圆振动装置,分析了两相激励电压值和相位差与椭圆形状的关系。实验与测试结果表明:超声振子的谐振频率符合设计要求,单向振动轨迹为正弦谐振曲线,两振动系统运动叠加形成椭圆轨迹;根据特定加工条件调整装置激励电压和相位差,可控制椭圆振动轨迹的形状。     

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。     

超声波镗削复合振型变幅杆的设计与分析

超声振动加工在难加工材料方面的应用越来越广,而在镗削中应用的不多。大量的实验证明复合振动加工效果优于普通振动加工效果,而如何在超声镗削加工中实现"复合"是一个棘手的问题。针对复合超声镗削,设计一种实现纵扭复合振动的变幅杆。阐述振型转换原理,进行结构计算,借助有限元软件ANSYS分析结构各项参数对性能的影响并总结规律,为复合超声镗削变幅杆的设计和优化提供了参考。     

椭圆振动研磨光整技术研究

针对平面光整问题,给出椭圆振动研磨的加工机理,进行了椭圆振动研磨实验.结果表明:椭圆振动、研磨精度高,达到平面光整的效果,并且研磨效率高,操作简便,椭圆振动研磨技术具有较高的实际应用价值.     

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。     

A new two-dimensional ultrasonic assisted grinding (2D-UAG) method and its fundamental performance in monocrystal silicon machining

A new two-dimensional (i.e., elliptical) ultrasonic assisted grinding (UAG) technique is proposed to achieve high material removal rate and high surface quality in the machining of hard and brittle materials such as monocrystal silicon. In this method, the workpiece attached on an elliptical ultrasonic vibrator is ground with a resin bond diamond grinding wheel under the presence of elliptical ultrasonic vibration. The elliptical ultrasonic vibrator is produced by bonding a piezoelectric ceramic device (PZT) on a metal elastic body (stainless steel, SUS304) and its detailed structure/dimensions are determined by FEM (finite element method) analysis. When two alternating current voltages with a phase difference are applied to the PZT at the same frequency that is close to the resonant frequency of the longitudinal mode and bending mode of vibrator, two ultrasonic vibrations are generated simultaneously, and the synthesis of the vibrations results in an elliptical motion on the end face of the vibrator. If the phase difference is set at 0° or 180°, two kinds of one-dimensional ultrasonic vibrations, i.e., axial or vertical vibrations, can be obtained. Grinding experiments are carried out involving monocrystal silicon to confirm the performance of the proposed elliptical UAG. In addition, grinding experiments under the presence of the axial and vertical ultrasonic vibrations and the absence of ultrasonic vibrations, i.e., conventional grinding, are also carried out for comparison. The obtained results show that: (1) compared with conventional grinding, the axial ultrasonic vibration results in greatest improvement in the work surface quality and a slight reduction in the grinding forces; (2) under the vertical ultrasonic vibration, the grinding forces are decreased significantly but the surface roughness is increased slightly; (3) elliptical ultrasonic vibration leads to the significant reduction of both the surface roughness and grinding forces. These indicate that the high efficiency and high-quality grinding of monocrystal silicon can be performed with the proposed two-dimensional ultrasonic assisted grinding technique.     

Study of machining accuracy in ultrasonic elliptical vibration cutting

The cutting speeds of the tool, the rake angle and clearance angle through the cycles of elliptical vibration cutting for separating type ultrasonic elliptical vibration cutting are defined initially in the present paper. Subsequently, a theoretical model of the thrust cutting force in ultrasonic elliptical vibration cutting is proposed, and the reason of the machining accuracy improvement by applying ultrasonic elliptical vibration is clarified theoretically. Finally, the effect of ultrasonic elliptical vibration cutting on machining accuracy is verified experimentally by utilizing an ultrasonic elliptical vibration cutting system.     

Experimental study on brittle–ductile transition in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire using single diamond abrasive grain

This study is carried out to investigate the material removal characteristics in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire using single diamond abrasive grain. The scratching experiments are performed to develop a fundamental understanding of the ductile–brittle transition mechanism during EUAG of monocrystal sapphire. An elliptical ultrasonic vibrator attached with a sapphire substrate was set up on a multi-axis CNC controlled machining center equipped with a single point diamond tool. The vibrator was constructed by bonding a piezoelectric ceramic device (PZT) having two separated electrodes on a metal elastic body, and an elliptical ultrasonic vibration was generated on the end-face of the metal elastic body when two phases of alternating current (AC) voltages with a phase difference are applied to their respective electrodes on PZT. In scratching experiments, the effects of ultrasonic vibration on the critical depth of cut a_c for the ductile–brittle transition region and the material removal ratio, i.e., the ratio of the removed material volume to the machined groove volume, f_ab, are investigated by the examination of the scratching groove surfaces with SEM and AFM. The obtained results show that the critical depth of cut in EUAG is much larger than that in conventional grinding without vibration (CG), and even the bigger vibration amplitude leads to a greater improvement. Although the values of f_ab in the ductile–brittle transition region in both EUAG and CG are less than 1, that in EUAG is bigger than that in CG. Furthermore, as the vibration amplitude increases, the value of f_ab is increased to eventually be close to 1. These show that it is prone to achieve a ductile mode grinding in greater vibration amplitude. It was also found that in the process there are two kinds of material removal modes, i.e., continuous cutting and discontinuous cutting modes, which are determined by the relationship between values of vibration amplitude and depth of cut. This study validates that the elliptical ultrasonic assisted grinding method is highly effective in ductile mode machining of hard and brittle materials.     

超声振动辅助加工表面微结构及其特性研究进展

针对超声振动复合加工方法种类繁多且表面微结构指征复杂等问题,阐述了表面微结构的内容和研究现状,论述了国内外超声切削、磨削、表面强化等方法的加工原理及超声振动加工表面微结构特性的试验研究方法,归纳了超声振动条件下表面粗糙度、表面微观形貌的建模方法及其特点,讨论了实验回归建模、数值解析建模和神经网络建模的研究进展,并预测了国内外超声振动表面加工的新技术领域和发展方向,对改善高性能难加工材料的表面微结构特性具有重要意义。     

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.     

超声振动磨削放电复合加工SiCp／Al试验研究

针对SiCp／Al的加工,提出一种超声振动磨削放电复合加工的方法．从加工效率、加工稳定性及表面质量等方面与电火花加工进行了对比试验研究。分析了两种加工方法的脉冲宽度和峰值电流对加工速度和表面粗糙度的影响,结果表明：电火花加工的表面粗糙度平均值为尺04．5μm,超声振动磨削放电复合加工的表面粗糙度平均值为Ra2μm：超声振动磨削放电复合加工的稳定性比电火花加工好,但加工速度较低。通过扫描电镜对两种加工方法下零件表面形貌和重熔层进行了观测,对试件表面进行了X射线衍射分析,表明采用超声振动磨削放电复合加工SiCp／Al复合材料可获得较好的表面质量。     

金刚石钻磨头超声振动钻磨硬脆材料表面质量的试验研究

硬脆材料以其优良的性能在生产实践中得到了广泛应用，但其低塑性、易脆性及不导电性等使得加工十分困难，尤其是超精密表面制作更加困难。为此，本文将超声振动引入普通钻磨中，介绍了超声振动切削原理，通过超声与普通两种方式下的表面粗糙度试验和微观形貌观察得出以下结沦：1）不同加工参数时，超声振动钻磨时的工件表面粗糙度值均低于普通钻磨时的表面粗糙度值；2）随着进给量、工件转速和输入功率的增加，超声和普通钻磨时的表面粗糙度均呈上升趋势；3）普通钻磨加工后孔壁表面有宽度和间距不均匀的沟槽，并且沟槽较宽，而超声钻磨加工后表面沟槽（划痕）较浅且均匀。     

Fundamental investigation of ultra-precision ductile machining of tungsten carbide by applying elliptical vibration cutting with single crystal diamond

This paper presents essential investigations on the feasibility of ductile mode machining of sintered tungsten carbide assisted by ultrasonic elliptical vibration cutting technology. It lays out the foundations toward efficient application of elliptical vibration cutting technology on tungsten carbide. Tungsten carbide is a crucial material for glass molding in the optics manufacturing industry. Its grain size and binder material have significant influence not only on the mechanical and chemical properties but also on the machining performance of tungsten carbide. In order to investigate the influence of material composition on tungsten carbide machining, a series of grooving and planing experiments were conducted utilizing single crystal diamond tools. The experimental results indicated that as compared to ordinary cutting where finished surface deteriorates seriously, ductile mode machining can be attained successfully by applying the elliptical vibration cutting technique. It was also clarified that the binder material, the grain size, cutting/vibration conditions as well as crystal orientation of the diamond tool have significant influence on the tool life and the machined surface quality. Based on these fundamental results, feasibility of micro/nano-scale fabrication on tungsten carbide is investigated. By applying amplitude control sculpturing method, where depth of cut is arbitrary changed by controlling the vibration amplitude while machining, ultra-precision textured grooves and a dimple pattern were successfully sculptured on tungsten carbide in ductile mode.