滚压加工中工件表层微塑性变形深度的解析分析和有限元验证

在简要介绍滚压工艺的基础上,对目前滚压技术的一些新发展进行了总结,并分析由此带来的对滚压加工机理研究的要求.得出了滚压过程中工件表层发生微塑性变形的深度与滚压力关系的解析公式.通过有限元分析方法采用lohnson-Cook流动应力模型就AISI 1045钢和IN718耐热合金两种典型材料的滚压进行了验证,比较结果表明推理假设和解析公式的准确性,为进一步更深入研究滚压机理特别是残余应力和冷作硬化的产生提供了一定的理论依据.     

超声滚压中颤振对零件表面质量的影响

基于超声波滚压加工,研究了超声滚压加工过程中颤振的产生机理。通过改变加工参数,进行超声滚压加工实验,采用HV-50A型维氏硬度计对超声滚压加工前后试样表面硬度进行测量,总结了重叠系数、主轴转速和滚压次数对超声滚压的影响规律,阐明了抑制颤振的方法和途径,为提高超声滚压系统的表面加工质量提供可靠指导。     

基于冷滚压工艺的谐波减速器柔轮疲劳寿命分析

依据冷滚压工艺产生的初始残余压应力对裂纹萌生,裂纹扩展的抑制机理,以冷滚压谐波减速器柔轮为研究对象,采用SWT方法和断裂力学理论对冷滚压柔轮分别进行裂纹萌生寿命、裂纹扩展寿命理论分析,并运用疲劳分析软件nCode Design-Life仿真分析进行相互验证。结果表明,冷滚压柔轮疲劳寿命在各阶段均优于机加工柔轮,能够有效延长谐波减速器使用寿命,验证了柔轮冷滚压工艺的优越性,并对延长柔轮的使用寿命提供了参考价值。     

球铁曲轴滚压伸长的分析与研究

对球轶曲轴滚压伸长做了研究,从晶相组织变化方面分析曲轴滚压伸长机理,并结合生产实际统计,分析其内在的分布规律.     

超声波滚压光整加工技术机理研究

超声表面滚压光整加工是一种新兴超声辅助表面改性技术,能够促使表面层晶粒纳米化,可显著降低材料的表面粗糙度值,改善表面应力分布,增强其耐磨、耐腐蚀性。研究了超声滚压加工机理及并建立力学模型。对超声加工系统各关键组成部分进行剖析,重点对超声变幅杆的结构进行了理论上的分析及设计,利用ANSYS有限元分析软件对变幅杆进行了模态与谐响应分析,验证了理论设计的合理性。确定了满足超声波滚压加工模式的本构模型,利用ABAQUS对超声滚压冲击过程做有限元模拟分析。     

滚压强化技术在铁路车轴表面处理中的应用

针对铁路车轴的表面损伤问题,提出了表面滚压技术应用于提高铁路车轴疲劳性能的可行性,综述了滚压强化技术的原理,详述了机械滚压技术、超声滚压技术、温滚压技术以及激光辅助滚压技术在铁路车轴表面处理中的应用现状,并指出完善滚压强化技术使得其能适应零件形式的多样性,优化获得高效稳定的滚压强化工艺,组织强化机理的实验和理论研究以及滚压后材料内部及深度方向残余应力的分布规律研究是未来的研究重点,为拓展其应用提供理论基础。     

曲轴滚压变形分析与滚压校直专家系统研究

分析曲轴圆角滚压强化和滚压校直的工作机理,研究曲轴滚压校直专家系统.     

磁力滚压技术及试验研究

磁力滚压技术是依据磁力驱动原理完成对非导磁管类工件内表面滚压加工的一种新型加工工艺。基于异性磁极相吸原理,其外部旋转磁场带动内部滚压工具同步转动,从而完成对工件内表面的光整加工。研究其加工机理,确定影响磁力滚压的主要因素;进行磁力滚压加工试验,确定了最佳工艺参数:当变频器输入频率为20Hz、轴向进给速度为0.4m/min、加工行程为5个时,工件内表面加工质量和效益达到最佳,验证了磁力滚压技术可有效提高不锈钢管工件内表面质量。     

根部圆角滚压强化的高精度钛合金螺栓疲劳失效研究

为研究根部圆角滚压强化处理后高精度螺栓的疲劳失效特征,开展根部圆角滚压强化的高精度钛合金螺栓疲劳失效断口的检测与研究。分析螺栓根部圆角滚压强化工艺的特点;对比螺栓滚压表面处理工艺对螺栓疲劳断裂的影响,对高精度螺栓疲劳试验后的外观和断口进行宏观形貌和微观显微特征研究;探讨涂铝钛合金螺栓的裂纹源特征。研究结果表明：根部圆角滚压螺栓的疲劳断裂断口呈现显著的韧性断裂特征;涂铝、喷丸或抛光处理能够增强其断口的等轴韧窝特征,证实了以韧性断裂为主的断裂机理,同时研究发现了铝涂层的界面剥离特征。     

飞机起落架活塞杆滚压加工工艺研究

活塞杆镀铬层的气密性质量问题,是航空企业飞机零件加工长期存在的问题.采用滚压器对活塞杆零件表面进行滚压加工是提高零件气密性和生产效率的最经济的手段.详细介绍了滚压加工的机理、装置、加工方法、工艺参数及其试验.试验证明,滚压达到了提高零件气密性和生产效率的目的.     

The relationship between surface roughness and burnishing factor in the burnishing process

This investigation examines burnishing using a microscopic perspective and elucidates the mechanism of surface roughness improvement by asperity deformation. This study uses tribology theory to propose a burnishing factor L _b to explain why the same burnishing result can be obtained in different burnishing conditions. The burnishing factor was determined by appropriate experiments, and the results demonstrated that a quadric curve relationship exists between surface roughness and burnishing factor and is analogous to the Stribeck curve in lubrication regimes.     

Editorial preface for special issue of FAIM 2015 published in IJAMT

Machining of critical components such as turbine compressor and pump parts is required to generate compressive residual stress on the surface layer in order to obtain high fatigue life. As an effective method to generate and improve the compressive residual stress of machined parts, burnishing has been widely used in industry. Despite its importance, few studies have investigated the mechanism of burnishing on surface residual stress. In this paper, the interference effects due to nearby burnishing points were revealed and investigated in the context of an elastic burnishing tool. The interference effects during the burnishing process help to enhance the compressive residual stress and improve the distribution of compressive residual stress on the burnished surface layer. In order to analyze the mechanism behind the interference effect more clearly, a 2D finite element model of the burnishing process was developed. It was found that the interference effect exists and becomes stronger as the feed rate is decreased. Small feed rates show a more apparent effect on the enhancement of interference effects. The results indicate that the interference effect of the workpiece surface is mainly created by the influence of the preceding burnishing points on the future burnished surface.     

Unique regenerative chatter in wiper-turning operation with burnishing process Part 1: Prediction and analytical investigation of generation mechanism,critical stability,and characteristics

The purpose of this paper is to understand the generation mechanism and to propose an analytical model of a unique regenerative chatter with the burnishing process in wiper-turning operations. The authors have found a unique chatter when using wiper inserts, which cannot be explained by the existing chatter theory found in the literature. The authors believe that this occurs because of the burnishing process of the wiper insert, which is the only difference from ordinary turning. At first, the burnishing process, which accompanies wiper inserts, is explained, and the turning operation with this process and the well-known regenerative effect in the cutting process is discussed. Then, the stability of the turning process with the regenerative effects in the cutting and burnishing processes are investigated, and an analytical model is proposed to evaluate the critical stability. Finally, the stability analysis of this unique chatter is conducted, and its generation mechanism and characteristics are examined clearly.     

Unique regenerative chatter in wiper-turning operation with burnishing process Part 2: Experimental verification of predicted generation mechanism,critical stability,and characteristics

In this paper, the predicted generation mechanism, chatter stability, and characteristics of the unique regenerative chatter with the burnishing process in wiper-turning operations are verified experimentally. It was found in the first part of the paper that the vibration regenerates in the burnishing process by the wiper part of the insert causing a novel type of chatter. In this second part, this chatter phenomenon is investigated in an experimental manner to verify its mechanism. The specific burnishing force, which is a gain factor characterizing the burnishing process, is determined by the Hertzian contact law. In addition, the specific cutting force is measured by a cutting test, the compliance of the flexible structure is measured by a hammering test, and the residual compliance is measured by a static indentation test. Then, experiments are conducted where the tilt angle and the feed rate are varied to find the critical stability. The conducted chatter experiments prove that the predicted generation mechanism, critical stability, and characteristics are true.     

金属材料超声表面强化技术的研究与应用进展

简要回顾几种传统的表面机械强化技术及其特点。对近年来得到迅速发展和应用的金属材料超声表面强化技术进行介绍和评述。这包括超声冲击处理技术、超声喷丸强化技术和超声深滚强化与滚光技术。介绍以上几种技术在国内外的研发和应用的历史和现状,对比几种技术在不同应用中的特点与限制,并与传统的表面机械强化技术进行比较。展望金属材料超声表面强化技术的发展与应用前景。在总结归纳的基础上,从强化机理、强化工艺、工程应用和技术规范等方面提出金属材料超声表面强化技术的研究和应用发展建议。为相关技术领域的研究机构、研究人员和工程应用单位提供有关金属材料超声表面强化的较为全面的信息。     

Developing and investigating of elastic ball burnishing tool

Burnishing, a plastic deformation process, is becoming more popular in satisfying the increasing demands of machine component performance and reliability. Thus, investigating the burnishing parameters in order to improve the product quality is especially crucial. The objective of this research is to evaluate the effect of different burnishing conditions on surface microhardness, surface roughness, and form accuracy. Orthogonal central composite experiment design was used to select the input parameters making them into the right order. Optimum burnishing parameters were established to minimize roughness and/or maximize surface hardening. Emperical formulas were developed to predict the surface microhardness and roughness of leaded brass obtained by burnishing under lubricated conditions.     

On the surface and tribological characteristics of burnished cylindrical Al-6061

Surface treatment is an important aspect of all manufacturing processes to impart specific physical, mechanical and tribological properties. Burnishing process is a post-machining operation in which the surface irregularities of the workpiece are compressed by the application of a ball or roller. In the present study, simple and inexpensive burnishing tools, with interchangeable adapter for ball and roller were designed and fabricated. Ball burnishing processes were carried out on aluminium 6061 under different parameters and different burnishing orientations to investigate the role of burnishing speed, burnishing force and burnishing tool dimension on the surface qualities and tribological properties. The results showed that burnishing speed of 330 rpm and burnishing force of 160 N produce optimum results. Meanwhile, a decrease in the burnishing ball diameter leads to a considerable improvement in the surface roughness up to 75%. On the other hand, parallel burnishing orientation exhibits lower friction coefficient compared to cross-burnishing orientation. Furthermore, ball burnishing process is capable of improving friction coefficient by 48% reduction and weight loss by 60-80% reduction of burnished surface of aluminium 6061. These findings are further supplemented by the surface features as seen in SEM photomicrographs.     

ENHANCEMENT OF SURFACE QUALITY AND TRIBOLOGICAL PROPERTIES USING BALL BURNISHING PROCESS

Surface treatment is an important aspect of all manufacturing processes to impart specific physical, mechanical and tribological properties. Burnishing process is a post-machining operation in which the surface of the workpiece is compressed by the application of a ball or roller to produce a smooth and work-hardened surface by plastic deformation of surface irregularities. In the present study, simple and inexpensive burnishing tools, with interchangeable adapter for ball and roller were designed and fabricated to meet the requirements of the present study. Then, ball burnishing processes were carried out on aluminium 6061 under different parameters and different burnishing orientations to investigate the role of burnishing speed, burnishing force and burnishing tool dimension on the surface qualities and tribological properties. The results showed that burnishing speed of 330 rpm and burnishing force of 160 N produce optimum results. Meanwhile, a decrease in the burnishing ball diameter leads to a considerable improvement in the surface roughness up to 75%. On the other hand, parallel burnishing orientation exhibits lower friction coefficient compared to cross burnishing orientation. Furthermore, ball burnishing process is capable of improving friction coefficient by 48% reduction and weight loss by 60–80% reduction of burnished surface of Aluminum 6061. These findings are further supplemented by the surface features as seen in SEM photomicrographs.     

Surface Texture Analysis after Hydrostatic Burnishing on X38CrMoV5-1 Steel

Ball burnishing is a plastic deformation process used as a surface smoothing and surface improvement finishing treatment after turning or milling processes. This process changes the surface stereometrics of the previously machining surface. Burnishing with hydrostatic tools can be easily and effectively used on both conventional and Computer Numeric Control(CNC) machines. The existing research of the burnishing process mainly focuses on the functional surface characterization, for example, surface roughness, wear resistance, surface layer hardness, etc. There is a lack of references reporting a detailed analysis of 3D parameters calculation with a mathematical model to evaluate the results of the ball burnishing. This paper presents the effect of ball burnishing process parameters with hydrostatic tools on the resulting surface structure geometry. The surface topography parameters were calculated using the Taly Map software. Studies were conducted based on Hartley's static, determined plan. Such a plan can be built on a hypersphere or hypercube. In this work, a hypercube was used. In the case of Hartley's plan makes it possible to define the regression equation in the form of a polynomial of the second degree. The input process parameters considered in this study include the burnishing rate, applied pressure, and line-to-line pitch. The significant influence of these parameters was confirmed and described as a mathematical power model. The results also showed a positive effect of hydrostatic burnishing on the roughness and geometric structure of the surface.     

Analysis and optimization of the ball burnishing process through the Taguchi technique

In the present study, the analysis and optimization of the ball burnishing process has been studied. The Taguchi technique is employed to identify the effect of burnishing parameters, i.e., burnishing speed, burnishing feed, burnishing force and number of passes, on surface roughness, surface micro-hardness, improvement ratio of surface roughness, and improvement ratio of surface micro-hardness. Taguchi tools such as analysis of variance (ANOVA), signal-to-noise (S/N) ratio and additive model have been used to analyse, obtain the significant parameters and evaluate the optimum combination levels of ball burnishing process parameters. The analysis of results shows that the burnishing force with a contribution percent of 39.87% for surface roughness and 42.85% for surface micro-hardness had the dominant effect on both surface roughness and micro-hardness followed by burnishing feed, burnishing speed and then by number of passes.