平面研磨过程中磨具均匀磨损的研究

固着磨料平面研磨加工中磨具的均匀磨损对于保证磨具和工件的加工面形精度具有极为重要的意义。根据固着磨料平面高速研磨中磨具均匀磨损的概念，通过力学和运动学分析，探讨了磨具均匀磨损的条件。分析表明，通过合理地选择偏心距，同时确定对应的磨具内外环中心线半径，并调整磨具的结构参数，可使磨具与镜盘接触区压强均匀分布，从而实现磨具的均匀磨损。     

平面固着磨料研磨机偏心距自动控制

研磨是精密和超精密加工中的一种重要加工方法。随着科学技术的进步,人们对加工精度的要求日益提高,对研磨加工的需求也越来越多。平面研磨是研磨中一种应用较广的加工,如:集成电路芯片、显示板、磁盘等,而且这些产品的应用十分广泛,因此,平面研磨的研究受到了高度重视。 由于传统的慢速散料研磨存在许多缺点,所以开发了采用固着磨料的高速研磨方法,使加工效率、加工成本等都有很大改善。特别是根据工件、磨具间相对运动轨迹密度分布和磨具磨损强度分布,设计磨具磨料密度分布,使磨具磨损均匀,这一技术的开发,把固着磨料高速研磨技术进一步推向实用化。 固着磨料研磨就是将磨料团结在磨盘上,制成专用磨具在高速研磨机上研磨,其原理如图1所示。在研磨时磨具由电机通过变速箱带动旋转,工件置于磨具之上。工件上面的压头通过压盖将工件压向磨具,向工     

不锈钢半固着磨具加工的工艺研究

为获得SUS440不锈钢的低／无损伤加工表面,实现高效加工,本文采用了一种半固着磨具。该磨具能够有效地阻止加工过程中大颗粒磨料对工件表面造成的异常深划痕,实现效率与加工质量平衡。本文使用了800。碳化硅磨料的半固着磨具对SUS440不锈钢进行研磨试验,研究了不同的加工参数对工件表面粗糙度和材料去除率的影响。试验结果显示在27kPa压力、60r／min转速下加工12min后,工件表面粗糙度Rn从250nm下降到50nm,材料去除率保持在1μm／min,实现了高精、高效的加工性能。     

半固着磨粒加工工艺参数对"陷阱"效应影响的离散元模拟

半固着磨粒加工以"陷阱"效应来降低加工质量和效率对磨粒尺寸分布均匀程度的敏感性,可提高精密、超精密加工的生产效率.对半固着磨具的"陷阱"效应进行离散元模拟,选取多种不同粒径大颗粒,分析加工载荷、工件与磨具的相对速度,以及工件摩擦因数三个加工工艺参数对"陷阱"效应的影响.仿真结果表明:加工载荷越大,半固着磨具"陷阱"效应发挥越好;而工件与磨具的相对速度和工件摩擦因数对半固着磨具"陷阱"效应影响不大;大颗粒尺寸越接近磨具中磨粒的尺寸,半固着磨具的"陷阱"效应发挥越好.     

抛物面研磨的材料去除率及表面粗糙度研究

固着磨料抛物面研磨是一种新型的抛物面加工方法,文中从单个磨粒的角度出发,讨论了研磨工艺参数对材料去除率和表面粗糙度的影响,建立了理论预测模型,然后利用计算机辅助软件对不同硬度工件材料的材料去除率和表面粗糙度进行了数值模拟仿真,最后用实验验证了模型的正确性,并得出结论:理论预测模型仅能预测材料去除率和表面粗糙度的变化趋势,并不能代替实验得出具体的实验数值,即固着磨料抛物面研磨的材料去除率与主轴转速、研磨压力的5/4次方成正比,与磨粒浓度的1/4次方成反比;表面粗糙度随磨粒尺寸和研磨压力的增加而增加,随磨粒浓度的增加而减小。     

工程陶瓷的游离磨料研磨加工工艺

通过PTC的研磨实验 ,研究了研磨时间、研磨速度、磨料种类和粒度以及研磨盘材料等工艺参数对PTC研磨效果的影响 ,并分析其研磨机理。研究结果表明 ,研磨质量主要受磨粒粒度的影响 ;为了提高研磨效率 ,同时保证表面质量 ,减少游离磨料对工件脆性断裂破坏 ,可采用固着磨料弹性研磨磨具进行研磨     

基于DEHPHI语言实现高速研磨机变速控制的一种方法

通过对固着磨料加工工艺的研究,提出了一种通过控制磨具转速来控制工件与磨具之间的相对运动速度,提高加工精度和效率的有关固着磨料高速研磨工艺研磨速度控制的技术方法.运用计算机的信息处理能力,应用以DELPHI语言编写的程序通过计算机与变频器的串行通讯实现对高速研磨机的变速控制.     

论光学玻璃的硬度

本文综合论述了几种常用的光学玻璃的硬度测量方法。对各类牌号的光学玻璃提出了在各该硬度测量方法中所表示的硬度。并从光学玻璃的结构以及光学玻璃磨削机理的角度进行了解释。本文提出了“固着磨料研磨相对硬度”的新概念,解释了为什么散粒磨料的研磨相对硬度不同于固着磨料研磨相对硬度的原因。光学玻璃的硬度是影响光学零件加工效率与表面光洁度的重要因素。本文着重对于各种硬度的表示方法作一简要叙述,并提出金刚石加工光学玻璃时的固着磨料研磨相对硬度。     

半固着磨具“陷阱”效应影响因素分析

以抛光后无表面损伤的单晶硅片为试件,以表面粗糙度Ra为指标,对半固着磨具的“陷阱”效应进行试验分析,讨论大颗粒浓度及尺寸、磨具硬度、加工载荷、磨具转速对“陷阱”效应的影响。研究结果表明：对一定尺寸的大颗粒,当大颗粒数量不超过临界值时,大颗粒可全部陷入,“陷阱”效应发挥;当大颗粒尺寸较大、磨具硬度较高、加工载荷较大时,不利于“陷阱”效应发挥。‘     

固着磨料研磨对机械密封表面耐磨性的影响

本文探讨了固着麻料研磨机械密封中,一些主要研磨参数,如产粒度,研磨压力和研磨速度等对工件已加工表面磨耐磨性的影响规律,为合理选择研磨参数提供依据。     

蜂窝状结构半固结磨料研磨盘的制备及应用

针对传统半固结研磨盘由于盘面较软使得加工衬底面形精度难以保证的问题,提出一种蜂窝状结构的半固结磨料研磨盘的设计与制备方法。该研磨盘采用环氧树脂蜂窝结构作为支撑“骨架”,减小研磨盘的变形,以保证研磨衬底的面形精度,同时采用含有金刚石磨粒的凝胶体作为半固结研磨介质实现对衬底的研磨加工,获得了较好的衬底表面质量。基于该原理制备了一套新型研磨盘,并用于蓝宝石衬底的双面研磨加工。试验结果表明,研磨后衬底表面粗糙度较小,表面划痕和裂纹少,能够获得较好的表面质量;相应地,研磨后蓝宝石衬底的面形精度不仅没有变差,反而得到很大的改善,研磨后衬底的翘曲度、弯曲度和总厚度偏差均大幅减小。另外,研磨效率也相对较高,材料去除率可达0.3～0.4 μm/min。试验结果证明了该新型结构研磨盘不仅可以获得较好的表面质量和较高的研磨效率,同时还可提高衬底的面形精度,可用于面形精度要求较高的薄片衬底零件的精密研磨加工。     

Sliding wear of an unlubricated frictional combination of ductile metal and brittle abrasive

The concept of determining wear from hypotheses concerning shear effects in metal surface regions was applied to the sliding wear of a smooth elastoplastically deformable metal substance and a rough brittle abrasive. Interfacial layers or lubricating depositions on either surface were neglected. The form of the contact was modelled using random fields for the roughness profiles. The resulting intensities of wear may be compared with published experimental results. The wear intensity level was quantitatively determined. Dependence on the nominal pressure and properties of the rough abrasive is thus explained. Instead of hardness the compressive strength of abrasive peaks is the dominant characteristic parameter.     

泥水盾构机密封用O形圈静态接触应力分析

利用ANSYS软件对泥水盾构机密封用O形圈进行建模,分析静态接触下接触应力与压缩率、流体压力、摩擦因数、硬度之间的变化规律,并拟合接触应力与压缩率和流体压力之间的函数关系。结果表明:随着硬度、压缩率、流体压力和摩擦因数的增大,主接触应力、Von-Mises应力和剪切应力均增大,其中摩擦因数整体上对O形圈应力影响很小;O形圈硬度越大,应力随压缩率的变化率越大;当O形圈承受较小流体压力时,应选用硬度较小的O形圈,使得Von-Mises应力、剪切应力均较小,O形圈产生裂纹、剪切失效的概率减小;当O形圈承受较大流体压力时,应选用硬度大的O形圈,以保证产生的主接触应力大于流体压力。接触应力与压缩率和流体压力之间满足正比例的关系,通过接触应力与压缩率和流体压力关系的拟合式,可计算得到不同流体压力下O形圈的合适压缩率。     

Wear behaviour of Al/(Al2O3p+SiCp) hybrid composites

In this study, dry sliding metal–metal and metal–abrasive wear behaviours of the aluminium matrix hybrid composites produced by pressure infiltration technique were investigated. These composites were reinforced with 37 vol% Al₂O₃ and 25 vol% SiC particles and contained up to 8 wt% Mg in their matrixes. While matrix hardness and compression strength increased, amount of porosity and impact toughness decreased with increasing Mg content of the matrix. Metal–metal and metal–abrasive wear tests revealed that wear resistance of the composites increased with increasing Mg addition. On the other hand, abrasive resistance decreased with increasing test temperature, especially above 200 °C.     

Investigation of the effect of diffusion bonding parameters on microstructure and mechanical properties of 7075 aluminium alloy

In the present study, diffusion bonding of aluminium alloy (AA7075) sheet materials which are used especially in the automobile and aerospace industry has been investigated at temperatures of 425 and 450 °C and pressures of 2 and 3 MPa for 180 min in argon atmosphere. The microstructural and mechanical properties of bonding have been characterized with different welding parameters such as bonding temperature and pressure. The microstructure was characterized by light optical microscope, scanning electron microscope and energy dispersive spectroscopy, while the mechanical properties were determined by tensile-shear tests and microhardness tests. The results obtained are discussed from both the microstructural and mechanical points of view. It was observed in the microstructural investigations that the interfacial oxide layer decreased with increasing of the bonding temperature and pressure. The maximum shear strength was found to be 131 MPa for the Al 7075 sample bonded at 450 °C and 3 MPa for 180 min. It is shown that in certain extent, the bonding temperature and bonding pressure have great effect on the joint shear strength. With the increasing of bonding temperature and pressure, the shear strength of the joints increases due to diffusion of atoms in the interface. The strength achieved after bonding were dependent on interface grain boundary migration and on grain growth during the bonding process. The maximum hardness value of the Al 7075 sample bonded at 450 °C, 3 MPa for 180 min is 92.5 HV_0.2. Increasing hardness with increasing temperature can be attributed to the formation of metallic bond at high temperatures and pressures.     

树脂结合剂含量对单晶硅片减薄加工用砂轮性能的影响规律研究

通过磨削实验,研究了树脂结合剂含量对用于单晶硅片减薄加工的金刚石砂轮的力学特性和磨削性能的影响,对砂轮的硬度、抗压强度、气孔率、磨削比、堵塞现象等进行了对比分析.结果表明,随着树脂结合剂含量增加,砂轮的硬度、抗压强度逐渐增大,气孔率变化不大.在单晶硅片的磨削实验中,随着树脂结合剂含量增加,砂轮的磨削比逐渐增大;树脂结合...     

金属O形环力学性能仿真分析与试验验证

金属O形环的力学性能对于密封系统的强度设计、密封性、可靠性等有着直接影响。为研究金属O形环的力学性能,以核反应堆压力容器用金属O形环为研究对象,考虑密封环的复合结构、材料弹塑性特征和工况条件,采用有限元方法建立O形环力学性能仿真模型,分析密封环的压缩回弹特性、应力应变特征、接触特性以及银层的作用,并进行相关试验验证。结果表明:该有限元模型计算结果与试验结果具有良好的一致性;压缩率过大或过小都将导致其密封性能下降;整个压缩回弹过程可分为弹性变形、塑性变形、法兰接触及回弹4个阶段,O形环的回弹补偿性能由其压缩率决定;镀银层对于O形环接触压力分布起到了均化作用,而对总体的压缩回弹特性影响不大。     

Eutectic bonding of austenitic stainless steel 316L to magnesium alloy AZ31 using copper interlayer

The eutectic bonding of magnesium alloy (AZ31) to austenitic stainless steel alloy (316L) was performed using pure Cu interlayers. The effect of hold time on the microstructural developments across the joint region and the related effect on bond shear strength were studied at a bonding temperature of 530°C. The bonding process took place through a sequential occurrence of solid-state diffusion of Cu into the magnesium alloy, eutectic phase formation, interlayer dissolution, and isothermal solidification. A (Mg–Cu–Al) ternary intermetallic phase formed within the joint and concentrated into the center of the bond during the solidification stage increasing the hardness value to a maximum average of VHN313 while the maximum recorded bond shear strength was 57 MPa achieving 69% of the AZ31 shear strength and about three to four times of the adhesive joints.