Prediction of Surface Topography at the End of Sliding Running-In Wear Based on Areal Surface Parameters

Running in is a complex process, and it significantly influences the performance and service life of wear components as the initial phase of the entire wear process. Surface topography is an important feature of wear components. Therefore, it is reasonable to investigate the running-in process with the help of surface topography for improvement. Because the surface roughness after running in is independent of the nature of initial roughness, it is difficult to predict the surface topography after running in based on unworn surface topography. Aiming to build a connection of surface topographies before and after the running-in process, a black-box model predicting surface topography after the running-in process was established based on least-squares support vector machine (LS-SVM), and the areal surface evaluation parameters were adopted as model variables. To increase the adaptability of the predictive model, the main factors of the work condition were also taken into consideration. The prediction effect and sensitivity of the model were tested and analyzed. The analysis indicates that the hybrid property of surface topographies before and after running in is closely related. Moreover, the surface topography after running in is influenced more by the initial surface topography than by the work condition.     

Changes of Surface Topography during Wear for Surfaces with Different Height Distributions

Surface topography is one of the leading factors affecting wear processes. This study investigated topographical changes of mechanical components with non-Gaussian surfaces under sliding wear. The Johnson translatory system of distributions was applied to describe different surface height distributions. A wear model that has been experimentally confirmed for sliding wear was used to describe changes of surface heights. Based on different wear particle size distributions generated during wear, variations of surface height distribution were investigated. Relationships between topographical change and original surfaces were established. Finally, the results predicted were compared with the results using a truncation wear model     

微细铣削表面形貌形成分析

基于最小切削厚度的概念,提出了微细铣削过程槽底表面几何形貌仿真模型。通过微细铣削表面形貌的仿真和表面粗糙度Ra值的计算以及微细铣削实验,对微细铣削表面粗糙度随着每齿进给量变化的规律进行了分析和描述。     

绿色加工中刀具磨损对表面粗糙度影响的研究

在切削镍基高温合金材料过程中,由于不稳定因素造成已加工表面粗糙度很难控制,尤其是刀具磨损直接影响着表面粗糙度。通过对冷风油雾、冷风和常温油雾等不同冷却切削条件下刀具磨损和工件表面粗糙度微观形貌的实验,研究了高速切削镍基高温合金材料时,在不同冷却切削条件下刀具磨损对工件表面粗糙度的影响,揭示了用冷风高速切削提高表面加工质量的规律。     

Wear and wear particles—some fundamentals

Each of the various processes by which material can be lost from a surface in service leaves its fingerprint both in the topography of the worn surface and in the size, shape and number of the particles which make up the wear debris. To use debris examination as a diagnostic aid in assessing the health of operating plant, which may contain many tribological contacts, requires not only careful and standardised procedures for debris extraction and observation but also an appreciation of the mechanisms by which wear occurs and the regimes in which each of the contacts of interest operates when displayed on an appropriate operational map.     

金属切削刀具后刀面的切削热研究

在以往的金属切削热研究中,认为刀具后刀面处产生的切削热很小而被忽略。文章应用平面热源法,建立了刀具后刀面与工件摩擦面的切削热模型,推导了该摩擦面的切削热分配和切削温度理论计算公式,对影响后刀面切削热的主要因素进行了分析。研究结果表明,当刀具后刀面磨损带宽度达到一定程度时,则刀具后刀面处产生的切削热不能忽略。     

多功能摩擦磨损实验机的研制

介绍了用于超硬材料工具性能参数检测分析的多功能摩擦磨损实验机的研制,该实验机通过分析金刚石工具在不同转速、压力、转矩下的磨损量,进行其工艺、配方的优化,为揭示超硬材料制品的工作机理和失效原因提供科学的实验数据,有助于开展更深层次的研究。     

Effect of Thermochemical Treatments on the Sliding Wear Mechanisms of Steels Under Boundary Lubrication

The effect of heat treatment, carburizing and plasma nitriding on the material-removal mechanisms and wear behavior of steels under boundary-lubricated conditions has been studied. A controlled procedure using mild abrasives under a light load was adopted in order to avoid long-term effects from severe wear in the running-in stage of pin-on-disc testing. Electron microscopy of the sliding surfaces showed that wear of the untreated steel took place by abrasive and adhesive mechanisms. Heat treatment by austenitizing, quenching and tempering (through-hardening) reduced the wear rate and carburizing produced a further reduction. The principal wear mechanisms in the both through-hardened and carburized steels was abrasive and delamination wear with adhesive wear being unimportant. Electron microscopy on cross-sections through the sliding surfaces of the carburized and through hardened steels showed extensive plasticity, cracks, and delaminated wear phenomena. The elimination of adhesive wear as a major wear mechanism is attributed to the influence of hardness on junction growth and the emergence of delamination wear to the effect of nano-crystalline carbides on fatigue life. Plasma nitriding resulted in an additional reduction in wear rate and the effective elimination of delamination wear. Electron microscopy on the plasma-nitrided steel revealed the presence of a dispersion of white layer regions, which raised the yield strength but also - resulted in micro-pitting due to a deformation mismatch with the matrix.     

The Effect of Argon-Enriched Environment in High-Speed Machining of Titanium Alloy

A major factor hindering the machinability of titanium alloys is their tendency to react with most cutting tool materials, thereby encouraging solution wear during machining. Machining in an inert environment is envisaged to minimize chemical reaction at the tool-chip and tool-workpiece interfaces when machining commercially available titanium alloys at higher cutting conditions. This article presents the results of machining trials carried out with uncoated carbide (ISO K10 grade) tools in an argon-enriched environment at cutting conditions typical of finish turning operations. Comparative trials were carried out at the same cutting conditions under conventional coolant supply. Results of the machining trials show that machining in an argon-enriched environment gave lower tool life relative to conventional coolant supply. Nose wear was the dominant tool-failure mode in all the cutting conditions investigated. Argon is a poor conductor of heat; thus, heat generated during machining tends to concentrate in the cutting region and accelerate tool wear. Argon also has poor lubrication characteristics, leading to increasing friction at the cutting interfaces during machining and an increase in cutting forces required for efficient shearing of the workpiece.     

车铣复合加工的刀具磨损强度分析

在车铣复合加工中心上,进行了车铣加工高强度钢工件材料的刀具磨损强度实验,分析了车铣切削用量对刀具磨损强度的影响.研究表明,在影响车铣刀具磨损的切削用量中,切削速度对车铣刀具的磨损强度影响最大.并以车铣刀具的磨损实验为基础,以切削速度为变量,建立了车铣高强度钢的刀具磨损强度分析模型.     

基于切削力的铣刀磨损在线监测研究

以实验方法研究了高速钢立铣刀后刀面磨损和铣削力之间的关系,建立了表征后刀面磨损和铣削力之间关系的数学模型,并提出了基于切削力的铣刀磨损监测算法。     

钛合金切削加工表面残余应力有限元仿真

采用Johnson- Cook失效准则,建立了钛合金的二维正交切削热-机械应力耦合有限元仿真模型,分析计算了不同切削条件下已加工表面残余应力的分布规律.结果表明:已加工表面层残余应力为拉应力,沿着深度方向由拉应力逐渐过渡到压应力.表面残余应力随着切削速度的增大而增大,在一定的前角变化范围内,随着刀具前角的增大,表面残余拉应力先增大后减小,而随着刀具后角的增大却减小.各加工参数对残余应力层的厚度影响都很小.     

钛合金切削加工表面残余应力有限元仿真

采用JobnSOn—Cook失效准则,建立了钛合金的二维正交切削热一机械应力耦合有限元仿真模型,分析计算了不同切削条件下已加工表面残余应力的分布规律。结果表明：已加工表面层残余应力为拉应力,沿着深度方向由拉应力逐渐过渡到压应力。表面残余应力随着切削速度的增大而增大,在一定的前角变化范围内,随着刀具前角的增大,表面残余拉应力先增大后减小,而随着刀具后角的增大却减小。各加工参数对残余应力层的厚度影响都很小。     

The Effect of Belt Finishing Process Variables on the Topography of Finished Surfaces

The high performance of industrial applications requires increasingly technical functional surfaces, particularly from the point of view of topography and micro texture. Belt finishing is one of the finest machining processes widely used to improve surface texture and to increase wear resistance and fatigue life. It modifies the surface topography in a wide range of roughness and waviness scales, and consequently modifies the functionality of the surface in terms of the bearing area, local plasticity, and durability. In this paper, the topographic signature of the belt finishing process on a wide range of wavelengths of surface topography is analyzed to track the effect of each working parameter, and makes it possible then to understand the principal physical mechanisms activated during the super finishing operations (cutting, ploughing, and friction). To this aim, a multiscale decomposition of the surface topography before and after finishing by using a 2D continuous wavelet transform is introduced.     

精密切削刀具磨损监控系统设计

设计了刀具磨损检测控制系统,采用EPF10K10TC144-4主控芯片、位移传感器,采用分布式算法编制了控制软件并进行了系统仿真。将数据输入到CNC系统,修改刀具参数,并在数控车床上进行了切削实验。对比研究结果表明,该系统避免了人工检测误差、机床频繁停机,减少了换刀次数和重新对刀引入的二次误差,延长了刀具有效使用时间,且加工效率、加工精度、产品合格率都有明显提高。     

新型陶瓷刀具材料的耐磨损性能

研究了近几年来所研制成功的几种新型陶瓷刀具材料切削加上高强钢、高温镍基合金、淬硬钢与铸铁时的耐磨性能。结果表明:加工不同材料时刀具的耐磨损能力不同,在实际应用时可根据需要选用合适的刀具材料。     

基于声发射技术的微切削加工表面形貌监测

采用声发射技术对工件材料为A16061-T6的微切削表面轮廓进行了实时测量.采集监控微切削加工表面时产生的声发射均方根信号,并与表面轮廓仪测得的结果进行对比.研究表明,声发射均方根信号与微切削表面形貌很好的相对应,因此,声发射技术适于微切削表面形貌的监测.研究了切削用量(每齿进给量和主轴转速)与表面形貌之间的关系,微切削的每齿进给量对表面粗糙度影响较大.     

硬质合金刀具铣削Ti6Al4V时刀具磨损及切削力研究

对硬质合金刀具在干切削状态下铣削Ti6Al4V磨损机理和切削力进行了试验研究,切削速度分别为40、80、120、160m／min。分析了切削力与切削方式、切削速度、切削路程的关系。最后,对刀具的磨损形态和磨损机理进行了探讨。结果表明粘结、扩散是硬质合金铣刀的主要磨损机理。     

磨损自补偿的载荷效应研究

通过载荷对磨损自补偿添加剂的性能的影响研究,发现在磨损自补偿添加剂ＳＷ４的作用下,钢－铜摩擦副的磨损量与载荷无关;而且载荷越大,钢－铜摩擦副的磨损自补偿效应越显著,这些结果不同于传统的摩擦学理论。因此。磨损自补偿添加剂ＳＷ４特别适合于重载工况下运行的钢－铜摩擦副,如轧钢厂压下系统的丝杆－螺母副,为提高这类重载钢－铜摩擦副的寿命和可靠性提供了一条有效途径。     

The Effect of Pulsed Laser Annealing on Wear and Corrosion Properties of Electroless Ni-P Plating

Electroless nickel-phosphorous alloy was plated onto quenched and hardened stainless steel. Laser surface treatments by YAG laser beams were carried out with the objective of improving -both the wear and the corrosion resistance of the platings. The friction and wear properties of the laser-treated platings were compared to unplated, untreated plated, and 400°C heat-treated plated substrates in pin-on-disc tests under unlubricated conditions. It was shown that laser treatments gave about a ten percent reduction in the friction coefficient compared with unplated substrates, and that controlled laser-treated plating improved the wear resistance of untreated plating to a level equivalent to 400°C heat-treated plating. It was found that the salt-spray corrosion resistance of the laser-treated platings was much greater than the unplated material and the 400°C heat-treated plating. The laser treatment is capable of improving both wear and corrosion resistance; and the wear resistance is externally governed by the hardness of the plating, and the corrosion resistance is governed by the crystal structure, especially the amount of amorphous nickel.