碳纤维增强复合材料螺旋铣孔切削力及加工质量研究

针对传统钻孔方法加工复合材料时易导致分层、撕裂等缺陷的问题,采用螺旋铣作为新的制孔技术,根据飞机装配现场的实际加工条件,构建以机器人为移动载体、螺旋铣孔终端执行器为加工单元、螺旋铣孔专用刀具为切削工具的加工系统,采用该加工系统对碳纤维增强复合材料(CFRP)螺旋铣孔关键工艺参数进行正交试验,并讨论了刀具主轴转速、每齿进给量和轴向切削深度等工艺参数对切削力的影响规律;通过对加工缺陷的监测,探讨了切削力与CFRP分层、撕裂等缺陷之间的关系;最后对工艺参数进行优化,经试验验证,优化后轴向切削力较优化前降低26%以上,孔入口及出口处均无撕裂、毛刺,加工质量最优。     

叠层滑移工艺对M21C层压板力学性能的影响

针对复合材料长桁毛坯制备的新工艺—叠层滑移工艺，考虑叠层滑移工艺的极限参数规划相关的力学性能试验矩阵，研究叠层滑移工艺对M21C层压板拉伸性能、压缩性能、弯曲性能、短梁剪切性能、开孔压缩性能和面内剪切性能的影响。试验结果表明:叠层滑移工艺对M21C层压板的开孔压缩性能无影响，拉伸性能、压缩性能、弯曲性能、短梁剪切性能和面内剪切性能均会有一定程度的下降。      

碳纤维复合材料超声辅助磨削加工表面质量影响因素及交互作用研究

碳纤维复合材料属于典型的难加工材料。为了改善超声辅助磨削加工碳纤维复合材料的表面质量,选取表面粗糙度(Ra)与磨削力(Fz)作为研究对象,主轴转速(A)、进给速度(B)、磨削深度(C)、工具粒度(D)这几个关键的工艺参数作为优化变量进行超声辅助磨削试验。结合响应面分析法,建立能够较好反映各优化变量对Ra和Fz的预测回归模型。通过方差分析和建立的响应面3D图,得出各参数及其交互作用对响应变量影响的显著性及其影响规律。借助Design Expert软件优化后得到在考虑这些交互作用下的最优工艺参数组合为:A=4500 r/min,B=8 mm/min,C=0.1 mm,D=275 um。     

设计杠杆零件的机械加工工艺规程及钻Φ12孔的专用夹具

本设计是杠杆零件的加工工艺规程及钻孔的专用夹具设计。杠杆零件的主要加工表面是平面、孔及键槽。并将孔、平面与键槽的加工明确划分成粗加工和精加工阶段以保证孔的加工精度。     

碳纤维增强树脂基复合材料制孔技术研究现状与展望

碳纤维增强树脂基复合材料(CFRP)具有优越的物理和力学性能,已在航空制造工业中得到大量应用。在主承力结构中,CFRP与金属材料的连接通常为机械连接。然而,CFRP的各向异性严重影响了其制孔质量。由于CFRP和金属具有截然不同的材料属性,CFRP/金属叠层结构制孔技术成为飞机装配过程中的一大难题。本文首先阐述了CFRP及其叠层结构在切削过程中的切屑形成机制、钻削力和钻削热的研究现状;其次,剖析了钻削过程中典型加工损伤,如毛刺与撕裂、分层缺陷及孔壁表面损伤的产生原因和影响因素;然后,介绍了CFRP制孔刀具材料和几何结构的优化设计研究进展,并综述了螺旋铣孔、变工艺参数钻削、"以磨代钻"和振动辅助制孔等多种CFRP及其叠层结构加工新技术及钻削过程的仿真研究。最后,借鉴钎焊工具和超声振动技术的独特优势,提出了磨粒有序排布钎焊金刚石工具的超声振动加工构想,以达到CFRP及其叠层结构的精密高效制孔加工这一目的。     

碳纤维机织物增强热塑性树脂复合材料热冲压叠层模型

针对碳纤维增强热塑性树脂复合材料(CFRTP)在热冲压成型过程中涉及到大变形、各向异性和多场耦合的现象,为了表征CFRTP在成型中的力学特征,基于有限元方法与连续介质力学理论提出了一种热塑性树脂基体与碳纤维机织物的叠层模型。与单独采用碳纤维机织物超弹性本构模型预测CFRTP成型性能的方法相比,提出的叠层模型能够表征成型温度、压边力和纤维取向对CFRTP成型缺陷的影响,并能优化热冲压成型工艺参数。这一叠层模型具有简单实用和材料参数容易确定的优点,为碳纤维机织物增强热塑性树脂复合材料成型的数值模拟和成型工艺优化奠定了理论基础。     

长轴深孔加工工艺优化

长轴是海下管道的关键零件之一,本文介绍了长轴深孔加工在研制过程中所遇到的技术难题,通过大量的试验研究,运用理论和实际相结合的方法,解决首件加工时间长、质量需提高的现状,经过对深孔加工的分析,找出了解决深孔加工的有效方法,解决了如下问题:(1)长轴深孔加工因系统刚性差,强度低,切削易产生振动、波纹,影响深孔加工精度,刀具耐用度和切削效率的问题;(2)在原长轴深孔加工工艺的基础上,提出了新的优化工艺路线;(3)从加工余量、加工参数、定位夹紧、刀具的选择、排屑方式等不同的角度进行了研究,提出了控制方案。     

SiCp/Al复合材料制孔崩边缺陷及其评价方法

对中高体积分数碳化硅颗粒增强铝基（SiCp/Al）复合材料制孔崩边缺陷进行了三维试验观测和统计分析,建立了制孔崩边缺陷模型,提出了一种基于崩边体积的SiCp/Al复合材料崩边缺陷程度评价方法。研究结果表明：崩边缺陷是SiCp/Al复合材料制孔的主要缺陷,且崩边缺陷主要产生在制孔出口处。采用该方法能够对不同参数下的制孔崩边缺陷程度进行客观真实的评价,对优化制孔工艺参数具有一定的指导意义。     

芳纶纤维增强树脂复合材料液氮冷却钻孔试验

芳纶纤维增强树脂（AFRP）复合材料是一种公认的难加工材料,加工中极易出现毛刺、烧蚀等缺陷,目前缺乏对其有效的加工工艺方法。为提高其加工质量,研究了液氮作为冷却介质的AFRP复合材料钻孔试验。在相同切削参数下进行了干式切削和超低温加工对比试验,测量了切削过程中的轴向切削力和孔临近区域的温度,并计算了孔的进出口毛刺面积和分层因子,分析了AFRP复合材料缺陷的成因,探讨了不同加工条件下缺陷的变化规律。结果表明:与干式切削相比,采用液氮超低温冷却加工的切削力升高了约15.2%,切削温度降低了约141.6℃,毛刺面积减少了约24.7%,因切削热产生的烧蚀现象得到抑制,明显改善了AFRP复合材料的加工质量。      

钢球挤压精加工内孔

内孔精加工的传统方法采用铰削、磨削和抛光等。若采用钢球挤压精加工内孔,则加工效率较高且成本低廉。虽然挤压加工工艺问世已有四十多年了,但在机械制造业中尚未广泛使用。     

Nano-second UV laser processed micro-grooves on Ti6Al4V for biomedical applications

Laser surface texturing can be used to produce well defined micro-grooves on biomedical materials such as Ti-6Al-4V. Such micro-grooves can be optimized to improve the integration with surrounding tissue. This paper examines the effects of Gaussian shaped beam profiles for nano-second laser processing on the laser micro-groove geometry, topography, and micro-structure of Ti-6Al-4V under atmospheric conditions. Laser and machining parameters such as pulse rate, scan speed, wavelength, groove width and pitch are shown to affect the resulting micro-groove geometries. In contrast to prior micro-groove studies using top-hat beam profiles with ultra-violet (UV) Excimer lasers or large area masking techniques, grooves produced with Nd:YVO₄ exhibit improved roughness parameters and reduced heat-affected zones. Initial processing parameters are established for the fabrication of micro-groove geometries on flat geometries that are relevant to biomedical implants and devices.     

Influences of processing parameters and heat treatment on microstructure and mechanical behavior of Ti-6Al-4V fabricated using selective laser melting

Selective laser melting (SLM) has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features. Therefore, this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM. The influences of various process parameters on the relative density, tensile properties, impact toughness, and hardness of Ti-6Al-4V alloy parts were studied. By employing parameter optimization, a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM. A relative density of 99.45%, a tensile strength of 1 188 MPa, and an elongation to failure of 9.5% were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters. The effects of annealing and solution aging heat treatment on the mechanical properties, phase composition, and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied. The ductility of the heat-treated Ti-6Al-4V alloy was improved. By applying a heat treatment at 850 ℃ for 2 h, followed by furnace cooling, the elongation to failure and impact toughness were found to be increased from 9.5% to 12.5%, and from 24.13 J/cm² to 47.51 J/cm², respectively.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00389-y     

TI-6Al-4V合金置氢-除氢组织与力学性能

为研究除氢处理对置氢钛合金组织与性能的影响,对Ti-6Al-4V合金在不同参数条件下进行了置氢与除氢处理,采用光学显微镜分析了置氢-除氢处理过程中Ti-6Al-4V合金微观组织的演化规律,通过室温拉伸试验研究了置氢-除氢处理后Ti-6Al-4V合金的力学性能,探讨了Ti-6Al-4V合金置氢-除氢组织与力学性能之间的相...     

Ti-6Al-4V合金表面超声振动滚压强化研究

采用超声振动滚压加工技术对Ti-6Al-4V合金表面进行处理,探究该项技术对Ti-6Al-4V合金表面质量的影响。通过对该工艺加工前后的Ti-6Al-4V合金进行表面粗糙度参数、XRD图谱、截面微观形貌、表层残余应力及显微硬度的对比分析,结果表明:经该工艺处理后的合金表面各项粗糙度参数皆有明显降低;加工后的合金表面XRD图谱的衍射峰减弱且宽化,衍射角向高角度方向偏移;加工后的合金表层β相组织相较加工前明显细化,且随着深度增加β相组织逐渐增大;在距离表面约50μm位置的残余应力值最大可达到-967 MPa;加工后的合金表面显微硬度可达到421HV,且在0~140μm的深度范围内,显微硬度随着深度的增加逐渐减小至与基体硬度一致。经超声振动滚压加工后的Ti-6Al-4V合金表面质量显著提高,有利于提高其零部件的使用性能。     

神经网络预测搅拌摩擦加工TC4超塑性行为

目的 研究搅拌摩擦加工工艺改性的Ti–6Al–4V双相钛合金的超塑性变形行为。方法 对360 r/min、30mm/min工艺条件下搅拌摩擦加工处理的TC4钛合金在不同的变形条件下进行超塑性拉伸实验,在实验数据的基础上构建以变形温度、应变速率和晶粒尺寸为输入参数且以峰值应力为输出参数的3–16–1结构的BP人工神经网络模型。应用所构建的BP人工神经网络模型对不同变形条件的Ti–6Al–4V钛合金的超塑性行为进行预测。结果 BP人工神经网络预测的精准度较高,实验应力值与预测应力值吻合度较高,相关系数R=0.991 3,相对误差为1.91%～12.48%,平均相对误差为5.92%。结论 该模型预测的准确性较高,能够客观真实地描述Ti–6Al–4V合金的超塑性变形行为。     

退火热处理对等径角挤压回收Ti-6Al-4V合金微观结构和显微硬度的影响

采用等径角挤压法回收Ti-6Al-4V合金切屑,并研究了回收样品和退火处理样品的微观结构和显微硬度。结果表明:在回收样品中,切屑之间的边界依然存在,而由于剧烈塑性变形,超细晶结构和较强的纤维织构得以形成。退火处理后,切屑边界部分消失,超细晶组织部分再结晶;而与此同时,退火处理样品展现出更宽泛的织构,再结晶晶粒并不存在择优取向。值得注意的是,退火处理样品的显微硬度较回收样品略有升高。     

Notch effects on high-cycle fatigue properties of Ti-6Al-4V ELI alloy at cryogenic temperatures

Notch effects on the high-cycle fatigue properties of the forged Ti-6Al-4V ELI alloy at cryogenic temperatures were investigated. Also, the high-cycle fatigue data were compared with the rolled Ti-5Al-2.5Sn ELI alloy. The one million cycles fatigue strength (FS) of the smooth specimen for the forged Ti-6Al-4V ELI alloy increased with a decrease of test temperature. However, the FS of each notched specimen at 4 K were lower than those at 77 K. On the other hand, the FS of the smooth and the notched specimens for the forged Ti-6Al-4V ELI alloy at 4 K were lower than those for the rolled Ti-5Al-2.5Sn ELI alloy. This is considered to be the early initiation of the fatigue crack in the forged Ti-6Al-4V ELI alloy compares with the forged Ti-5Al-2.5Sn ELI.     

Analysis of Beam Material Interaction in Welding of Titanium with Fiber Lasers

Ti-6Al-4V is one of the most widely used titanium alloy in industrial applications because of its lightweight and corrosion resistance. The new generation of high power fiber lasers presents several benefits, namely, high power, low beam divergence, and compact size. These lasers can be used in a diversity of materials as the low wavelength that characterizes them allows absorption by almost all metals and alloys. This article presents a research about the weldability of the Ti-6Al-4V alloy using a fiber laser. Weld beads produced with different processing parameters were morphologically characterized under optical microscopy and the microstructures obtained were investigated.     

选区激光熔化工艺参数对Ti-6Al-4V成形质量的影响

选区激光熔化是一种利用高能束选择性熔化金属粉末进而直接制造复杂几何形状产品的增材制造技术。采用选区激光熔化成形Ti-6Al-4V样品,分析影响选区激光熔化成形质量的主要因素,采用体式显微镜、金相显微镜、扫描电子显微镜(SEM)、显微硬度计系统研究了不同工艺参数对Ti-6Al-4V合金选区激光熔化成形样品的表面形貌、致密度、组织、显微硬度的影响规律。研究得出Ti-6Al-4V合金选区激光熔化成形的优选工艺参数为:扫描功率450W,扫描速度2 500mm/s,扫描间距0.07mm,该工艺参数下打印出的样品具有较为优良的成形质量,致密度高达97.8%,显微硬度平均值为446HV。     

EDM of Ti-6Al-4V: Electrode and polarity selection for minimum tool wear rate and overcut

Titanium and its alloys especially Ti-6Al-4V are being widely used numerous application areas. In addition to have iconic properties, Ti-6Al-4V is considered as challenging material in machining perspective that is why it has captured global research focus. In this research, electric discharge machining of Ti-6Al-4V has been carried out by employing four different types of electrode materials (graphite, aluminum, copper, and brass) assigned with two alternate polarities (positive and negative). Selection of the most appropriate tool material and electrode polarity is the important aspect needed to be explored for this alloy. In addition to polarity, discharge current, and pulse time ratio have been considered as process variables owing to have their direct influence in electric discharge machining. Taguchi L9 array has been employed for each of the four electrodes with positive polarity and similarly L9 with negative polarity. Thus, a total number of 72 experiments have been conducted. Tool wear rate and overcut (OC) around the machined surfaces are the response characteristics to be investigated in order to achieve minimum amounts of both of these two responses. Selection of the most suitable tool with common tool polarity has been carried out meeting the decision criteria of minimum tool wear and minimum OC.