二次碳化物对基体三体磨粒磨损特性珠影响

选用三种不同碳，铬含量的耐磨钢，通过热处理获得不同数量的二次碳化物和马氏体基体、研究了二次碳化物对基体三体磨粒磨损特性的影响。试验结果表明，当切削磨损机理占主导地位时，二次碳化物对基体磨粒磨损能力提高有利；当低周塑变疲劳磨损占主恃位时，二次碳化物对基体抗     

二次碳化物对基体三体磨粒磨损特性的影响

选用三种不同碳、铬含量的耐磨钢，通过热处理获得不同数量的二次碳化物和马氏体基体。研究了二次碳化物对基体三体磨粒磨损特性的影响．试验结果表明；当切削磨损机理占主导地位时，二次碳化物对基体抗磨粒磨损能力提高有利；当低周塑变疲劳磨损占主导地位时，二次碳化物对基体抗磨粒磨损能力提高不利。     

新型高温磨粒磨损测试装置及方法

为研究涂层等表面工程零件的磨损性能,介绍了一种新型的高温磨粒磨损测试装置和方法,可以模拟研究高温氧化腐蚀和磨粒磨损交互作用,并研究了测试温度、测试载荷、测试时间和三种磨料对涂层磨粒磨损测试结果的影响.结果表明,这种高温磨粒磨损测试方法可以评价不同温度和载荷条件下涂层的耐磨粒磨损性能;高温磨粒磨损测试装置结构简单,运行稳定,所测试的数据准确、重现性好;当温度和载荷变化时,涂层的耐磨粒磨损性能也会变化.     

配副对耐磨钢磨粒磨损特性的影响

讨论了在动载三体磨粒磨损条件下，马氏体钢配副变化对磨粒磨损系统耐磨性的影响。结果表明，对给定的下试样，随着上试样耐磨材质的不同，磨粒的存在方式、运动方式发生变化，改变了磨粒对材料的作用方式，使磨损机理发生了变化，引起配副下试样耐磨性呈不同的变化特征。     

基于单颗磨粒切削的CBN铰珩工具磨粒磨损研究

采用单颗磨粒试验方法,以4Cr13不锈钢为修整材料,研究大长径比CBN铰珩工具修整过程中的磨粒磨损特性。试验结果显示:与普通切削相比,超声切削时的平均切削力降低60%～80%,但磨粒在短时间内大块破碎,磨削比严重下降。超声切削时的磨粒?工件接触比在0.6～0.8,磨粒主要处于断续切削过程,其最大切削宽度比普通切削时的增加2.7倍,且磨粒受到的最大瞬时切削力增加。根据点云信息对磨粒进行逆向建模,并对建立的单颗磨粒切削仿真模型的瞬时切削力进行定量分析。仿真结果显示:超声切削时的最大切向力比普通切削时的增加20%以上,且力的波动幅度超过80%。      

铸造高钼高速钢的显微组织与磨粒磨损性能

采用铸造法制备了钼含量为10wt%的高钼高速钢,利用SEM、XRD、EDS分析了显微组织,并利用ML-100型销盘式磨损试验机测试了磨粒磨损性能。结果表明:高钼高速钢中的碳化物为M_2C型碳化物,经过热处理后,其基体组织为马氏体和奥氏体。磨粒尺寸与载荷对高钼高速钢的磨损性能有显著影响,随着磨粒尺寸或载荷增大,磨损量显著增加。磨损失效形式为磨粒对高速钢的显微切削。当磨粒尺寸及载荷较小时,M_2C型碳化物能有效地发挥作用而抵抗磨粒的显微切削,反之,当磨粒尺寸及载荷较大时,磨粒经过碳化物时会对其耕犁而掀起碳化物,碳化物不能有效的保护基体,导致磨损较为严重。     

硬质涂层的微磨粒磨损评价方法

微磨粒磨损试验是最近发展起来的评价涂层耐磨性的方法。比较了通过微磨粒磨损试验和球（销）盘磨损试验评价硬质涂层耐磨性的差别,论述了涂层耐磨性评定结果与涂层零件使用性能之间的关系。被测试的涂层为CrN和CrSiN,工件为高速钢钻头。研究结果表明,用微磨粒磨损试验测得的微粒磨损系数（ka）与镀层钻头的钻孔寿命之间存在一定关系,也即当后。小于某一数值时,镀层钻头的钻孔寿命较高。而用球（销）盘磨损试验法测定的比磨损率则与钻头的钻孔寿命无内在联系。     

钎焊金刚石磨削石材过程中磨粒磨损状态研究

通过数字视频采集系统跟踪观察钎焊金刚石砂轮磨削过程中磨粒表面形貌变化.研究了钎焊金刚石砂轮在磨削花岗石材料过程中,金刚石磨粒的出刃高度和磨损状态的变化规律.结果表明,钎焊金刚石工具在加工过程中,钎焊金刚石磨粒可分为六种磨损状态:完整晶形、微观破碎、宏观破碎、磨平、折平和脱落.磨粒磨损路径主要是以完整→微观破碎→宏观破碎→脱落的方式进行.金刚石磨粒在磨损过程中,可分为初期磨损、正常磨损和剧烈磨损三个阶段.     

Experimental investigation into cutting forces and active grain density during abrasive flow machining

It is important to know cutting force components and active grain density during abrasive flow machining (AFM) as this information could be used to evaluate the mechanism involved in AFM. The results show that cutting force components and active grain density govern the surface roughness produced during AFM process. In this paper, an attempt has been made to study the influence of these two parameters, namely cutting force and active grain density, on the surface roughness. This study will help in developing a more realistic theoretical model.The present paper highlights a suitable two-component disc dynamometer for measuring axial and radial force components during AFM. The influence of three controllable variables (extrusion pressure, abrasive concentration and grain size) on the responses (material removal, reduction in surface roughness (R_a value), cutting forces and active grain density) are studied. The preliminary experiments are conducted to select the ranges of variables by using single-factor experimental technique. Five levels for abrasive concentration and six levels for extrusion pressure and abrasive grain size were used. A statistical 2³ full factorial experimental technique is used to find out the main effect, interaction effect and contribution of each variable to the machined workpiece surface roughness. The machined surface textures are studied using a scanning electron microscope.     

磨料微粉粒度检测与数据处理系统设计

针对目前沉降管测定微粉粒度普遍存在数据记录和处理过程中人为因素较大,影响测试结果的准确性等问题,利用斯托克丝定律和新一代微处理器的特点,设计了磨料微粉粒度检测与数据处理系统。论文介绍了沉降法基本原理和计算数学模型、沉降液的密度和黏度与温度修正关系,给出了系统软硬件电路。通过对相关样品进行实际测量和数据处理分析,结果表明:数据记录和处理稳定、操作方便、曲线显示美观,易于扩展等特点,具有广泛的应用前景。     

工艺参数对NM500耐磨钢力学性能和三体冲击磨损性能的影响

对一种含0.27%C的工程机械用低合金高强度耐磨钢NM500进行轧制及两相区热处理试验,研究了普通高温轧制+空冷、高温控制轧制+空冷、高温控制轧制+层流冷却以及低温控制轧制+层流冷却工艺参数对实验钢两相区热处理后力学性能和三体冲击磨料磨损性能的影响。结果表明,轧制及轧后冷却工艺参数对试验钢两相区热处理后的性能影响较大,低温控制轧制+层流冷却较好的细化了原始铁素体晶粒,在经过适当的两相区热处理后得到保留,有利于提高实验钢的低温冲击韧性和耐磨性能。     

航发钛合金叶片金刚石砂带磨削的磨粒磨损研究

金刚石砂带精密磨削航空发动机钛合金叶片时,砂带磨损对加工精度及表面质量一致性影响很大。针对这一问题,利用ABAQUS软件开展单颗磨粒磨削过程仿真研究,进而进行航发钛合金叶片金刚石砂带磨削试验。仿真及试验结果表明:在磨削速度为10～20 m/s时,摩擦接触点的温度达700 K以上,且随磨削速度的增大而升高;砂带磨损程度随磨削速度的增大而升高,与磨削速度对摩擦接触点磨削温度的影响规律一致。M10/20金刚石砂带的磨损形式为磨粒损耗和磨粒脱落,磨屑的黏结加剧了砂带的磨损。      

单颗磨粒的平面磨削三维动态有限元仿真

将磨粒简化为圆锥形,利用Deform-3D软件,进行了单颗磨粒的平面磨削的三维动态有限元仿真。分析了砂轮与工件表面之间的摩擦系数相同而磨削速度不同时对磨削力产生的影响,以及磨削速度相同而摩擦系数不同时对磨削力产生的影响。结果表明：未变形磨屑厚度不变时,单位磨削力随着砂轮速度的增加而增大,在砂轮速度的低速区,单位磨削力增加较快,而在砂轮速度的高速区,单位磨削力增加得较慢;在磨削速度不变时,单颗磨粒的磨削力随着摩擦系数的增加而增加。     

单颗磨粒划擦SiCf/SiC陶瓷基复合材料的试验研究

为研究SiC纤维(SiC_f)增强SiC陶瓷基复合材料(SiC_f/SiC)的磨削损伤机理,搭建试验平台开展单颗磨粒划擦试验,测量划擦力并观察其表面损伤形式,研究磨粒形状、划痕深度和SiC_f取向对复合材料磨削机理的影响。试验结果表明:SiC_f/SiC陶瓷基复合材料的划擦损伤形式主要有基体崩碎、纤维裂纹、断裂和拔出等。在SiC_f/SiC陶瓷基复合材料划擦过程中,尖锐状磨粒的划擦力更小,且整条划痕的表面损伤范围较扁平状磨粒的小。用扁平状磨粒划擦但纤维取向γ= 0°时,划痕形貌中纤维断裂、纤维拔出等损伤形式出现较少。      

大颗粒形状对半固着磨粒磨具"陷阱"效应影响的离散元仿真

本文基于离散元的方法研究了不同顶角的大颗粒对半固着磨粒磨具"陷阱效应"的影响,在研究的过程中应用了PFC2D离散元软件,分别模拟了90°、120°和150°顶角的大颗粒,采集到大颗粒压入半固着磨粒磨具时受到的法向作用力和竖直位移之间的曲线图.由于半固着磨粒磨具内部布满了空隙,使得大颗粒能比较容易的陷入磨具中,减少了大颗粒对工件表面的损伤.通过以上大颗粒离散元模拟可知,半固着磨粒磨具"陷阱"效应持续的时间和大颗粒顶角大小成反比关系,即大颗粒的顶角越小,磨具"陷阱"效应持续时间越长,所以大颗粒的顶角大小是影响半固着磨粒磨具"陷阱"效应发挥的重要因素.     

基于DEFORM的单颗磨粒对零件表面冲击仿真与实验

磨削加工过程中,工件表面材料的去除是磨粒冲击、切削、划擦等综合作用的结果。为了研究磨削过程中的冲击现象,针对45~#钢工件,运用DEFORM-3D软件对单颗磨粒对工件表面的冲击强化过程进行有限元仿真,获得了工件内部应力场的分布情况,对磨削过程中工件表面等效应力与应变率进行了分析,得到了磨削参数对磨削过程的影响规律。对等效应力的分析表明:磨削过程中,工件受力是由很多脉冲力合成的。对应变率的分析表明:磨粒对工件表面的冲击强化效应显著。实验研究结果验证了理论与仿真分析结果的正确性,采用的仿真方法可有效分析与预测工件表面强化层指标。     

On ultrasonic assisted abrasive flow finishing of bevel gears

Finishing of bevel gears is an important requirement in many machining shop floors. Variants of abrasive flow machining (AFM) could be plausible solutions for finishing such parts with intricate geometries. In the present work, a relatively new variant of AFM called ultrasonically assisted abrasive flow machining (UAAFM) technique was employed to finish bevel gears made of EN8 steel. An analysis of the process has been presented with suitable illustrations. A finite element simulation of the behavior of the medium during finishing of bevel gears using the UAAFM process has been presented. A 3D model was constructed to simulate the flow of medium through the outer wall of the gear tooth surface using computational fluid dynamics (CFD) approach. The velocity, pressure and temperature values along the length of the workpiece were computed for both UAAFM and the conventional AFM processes. Further, the effectiveness of the process was investigated through experimental trials by conducting a comparison study between classical AFM and UAAFM. Ultrasonic frequency, extrusion pressure, processing time and the media flow rate were considered as the input variables while improvements in surface finish and material removal were considered as the monitored outputs. Results confirm that improvements in surface roughness and material removal are significantly higher than those obtained with conventional abrasive flow machining. The study further reveals that, the applied high frequency (ultrasonic) vibration to the workpiece has the maximum influence on the process responses among the variables considered.     

Simulation of surface grinding process, part 2: interaction of the abrasive grain with the workpiece

This paper is the second part of the two-part series, which describes the kinematic simulation of the grinding process. The complex wheel–workpiece interaction is taken into consideration in the generation of the workpiece surface. An algorithm is proposed to identify the active abrasive grains and their attack angles from the wheel topography. Based on the critical values of the attack angle, the abrasive grain is determined either to cut, plough or rub the workpiece. A numerical example is used to validate the approach.