超声辅助磨削加工碳纤维复合材料的磨削力分析

针对碳纤维复合材料采用普通磨削时存在磨削力大、刀具磨损快、工件加工效率低等问题。在国内首次基于超声辅助磨削对航空碳纤维复合材料进行磨削力研究,选择主轴转速、超声振幅、进给速度和磨削深度主要的磨削工艺参数,深入开展航空碳纤维复合材料的超声辅助磨削力对比研究。研究结果表明:加工碳纤维复合材料工件时,超声辅助磨削能明显降低磨削力,即使在最差的加工条件下,即较低的主轴转速、较高的进给速度、较大的磨削深度的条件下,超声辅助磨削对磨削力的降低作用越显著。超声辅助磨削无论在航空碳纤维复合材料的粗加工还是在精加工中,都能达到更好的加工效果,在改善航空碳纤维复合材料的加工条件、增加工具使用寿命和提高加工效率上都有明显的作用。     

碳纤维增强树脂基复合材料加工表面粗糙度对疲劳性能的影响

采用磨削和铣削(顺铣、逆铣)加工工艺获得不同表面粗糙度Sa的碳纤维增强树脂基(CFRP)复合材料试样并进行拉-拉疲劳试验,基于刚度退化模型分析了加工表面粗糙度对疲劳性能的影响.结果表明:磨削、顺铣和逆铣试样的Sa分别为1.2,3.2,5.9μm;磨削试样0°纤维铺层表面纤维缺失,存在空隙,铣削试样在45°纤维铺层表面存...     

C/SiC复合材料组织对磨削力与加工表面质量的影响

采用树脂结合剂金刚石砂轮对C/SiC复合材料与SiC陶瓷进行了平面磨削加工试验,通过对比两种材料的磨削力及磨削加工表面质量,分析了C/SiC复合材料组织与其磨削加工特性的 关系。研究结果表明,C/SiC复合材料中碳纤维及SiC基体皆以脆性断裂方式实现材料去除;与SiC陶瓷的加工表面(其表面粗糙度值Ra为0.2~0.3μm)相比,C/SiC复合材料磨削时由于碳纤维层状断裂、拔出及其与SiC非同步去除现象导致其加工表面粗糙度值较高, Ra为0.8~1.0μm;C/SiC复合材料磨削力较小,是相同工艺参数下SiC陶瓷材料磨削力的35%~76%。     

碳纤维复合材料数控钻磨工艺及装备研究

针对传统的碳纤维复合材料钻孔加工工艺易产生缺陷的问题,开展了"以磨代钻"新工艺的研究,并研制了新型电镀超硬磨料刀具.采用西门子802D数控系统实现对碳纤维复合材料构件数控钻磨工艺装备的控制,阐述了数控系统的组成及主要参数的设计.实践证明,应用"以磨代钻"新工艺的钻磨装备可获得较高的加工精度及表面质量,满足当前碳纤维复合材料构件孔加工的工业要求.     

碳纤维复合材料超声辅助磨削机理研究

针对碳纤维复合材料超声辅助磨削机理开展工艺实验研究,第1步对超声辅助磨削工具开展堵塞试验,第2步研究超声辅助磨削的去除机制与碎屑形貌。最后得出超声辅助磨削方法在碳纤维复合材料的加工中有明显的优越性,不管是零件粗加工,还是零件精密加工,均能够在很大程度上减少工具磨损度,延长刀具使用期、优化表面质量等。     

不同体积分数SiCp/Al复合材料精密磨削试验研究

对体积分数为40%和60%的SiC_p/Al复合材料进行ELID精密磨削试验。分析了体积分数对加工材料物理化学性能的影响;运用正交试验和极差分析方法探究了磨削深度、砂轮线速度、电解电流及占空比对磨削加工表面质量和精度的影响规律,并得到优化工艺参数。采用相同优化工艺参数,对不同体积分数SiC_p/Al复合材料进行ELID精密平面磨削试验,对所得到的加工样件表面质量、形貌和机械加工性能进行分析研究。试验结果表明:SiC_p/Al复合材料ELID精密磨削加工表面质量和机械加工性能随着体积分数的增加而降低。采用ELID磨削技术可以实现对SiC_p/Al复合材料的精密加工,加工样件的表面粗糙度为95nm和106nm。     

纤维方向对单向C/SiC复合材料磨削加工性能的影响

为了研究碳纤维编织复合材料的去除机理,探明纤维编织方向对磨削加工性能的影响,设计并制备了单向复合材料C/SiC,并沿纤维典型方向进行了磨削实验。结果表明,单向复合材料磨削时,切向磨削力和法向磨削力均呈如下规律：法向磨削＞纵向磨削＞横向磨削;磨削加工过程中表面粗糙度值呈如下规律：纵向磨削＞法向磨削＞横向磨削。对加工表面显微形貌的分析,揭示了陶瓷基复合材料微观多向去除机理。     

碳纤维复合材料车体地板长大型材粘接工艺研究及装备设计

碳纤维复合材料应用于轨道车辆车体地板结构,较铝合金车体地板减重33%。碳纤维复合材料长大型材结构采用拉挤成型工艺,连接方法以粘接为主。本文优化设计了碳纤维复合材料车体地板长大型材的榫槽粘接接头,并通过剪切拉伸试验验证了该接头形式的可靠性。在此基础上研发了一套由定位系统、控制系统、执行系统组成的柔性化粘接工艺装备,该工艺装备通过更换仿形支撑尼龙模板来实现不同车型和不同型材连接的柔性化切换,满足车体地板用碳纤维复合材料长大型材粘接工艺要求。     

复合材料磨削切边关键技术及装置研究

提出了一种双锯片磨削加工复合材料的切边方法。通过对复材的切削机理进行研究,设计了一种可安装在数控机床上的磨削切边机构,在复材切边中不产生使材料分层的拉应力。试验结果表明,采用双锯片磨削加工的方法,可以高质量、高效率完成对碳纤维复合材料的切边加工。     

超声辅助加工中磨削热模型的建立与验证

对超声振动辅助磨削碳纤维复合材料过程中产生的磨削热进行研究。在特定的条件下,建立了相应的磨削热传递模型并对此模型进行了有限元仿真;在相同的条件下,通过工件上布置的光纤光栅传感器测量超声振动辅助磨削碳纤维复合材料在实际加工中产生的磨削温度。对比仿真与实验结果,验证了磨削热传递模型的正确性。结果表明:磨削热传递模型可以很好地预测磨削过程中热量的传递状态,为后续优化实验参数、提高工件表面质量提供了理论依据,具有较高的实用价值。     

汽车弧形石棉制动片的砂带磨削

介绍了用周边固定砂带或砂布的磨头，加工石棉制动片的工艺方法、设备结构和加工特点。实践证明这种方法具有加工设备简单，工艺灵活性大，适应性强，工效高、工艺成本低等特点。     

New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness(Ra) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid solidification presented can significantly improve the finishing performance and service life of magnetic abrasive, and provide a more practical approach for large-scale industrial production of magnetic abrasive.     

圆柱滚子外圆精密加工技术综述

圆柱滚子外圆精密加工技术作为圆柱滚子制造流程的终加工手段,对保证圆柱滚子的形状精度、尺寸精度、表面质量及其一致性起到关键作用。目前,依据加工原理不同,圆柱滚子加工方法主要分为无心磨削和无心超精研的工业主流传统加工方法,以及定心往复超精研、电化学机械光整、磁流体研磨、双平面方式超精研抛等非传统加工方法。介绍了上述不同加工方法的基本加工原理和研究现状,在加工精度、表面质量、生产效率等方面讨论了各加工方法的优缺点;展望了圆柱滚子外圆精密加工技术未来的发展方向,包括超精密工件和设备、高效自动化生产、高柔性生产、微小型零件、复合工艺、智能装备等。     

超高速磨削砂轮技术发展

高速超高速磨削加工是先进制造方法的重要组成部分,集粗精加工于一身,达到可与车、铣和刨削等切削加工方法相媲美的金属磨除率,而且能实现对难磨材料的高性能加工。本文主要论述了高速超高速磨削工艺技术的特点;分析了超高速砂轮用电镀或涂层超硬磨料(CBN、金刚石)的特点以及修整方法,介绍了广泛应用于高速及超高速磨床的德国Hofmann公司砂轮液体式自动平衡装置。     

行星式双平面多工件研磨盘设计

行星式研磨是在传统研磨机构的基础上,通过改变行星结构获得理想研磨轨迹,从而来提高研磨精度和效率的一种研磨方式。以实现多工件双平面同时研磨为需求．设计了对其运动轨迹做了具体分析,根据加工要求设计出具体的行星式研磨盘结构,并进一步对该研磨盘进行了运动几何学仿真以验证其可用性。这种研磨机在保证研磨加工精度和加工品质的同时,还可在一定尺寸范围内实现不同截面、多个工件的同时研磨,提高了加工效率,降低了加工成本。     

磨料水喷嘴的优化设计

为提高磨料水射流加工设备中磨料水喷嘴加工性能,通过实验研究了磨料水喷嘴几何形状对喷嘴磨损的影响,并研究了磨料水喷嘴机械结构和加工性能,最终确定优化加工条件.     

太阳能硅片游离磨料电解磨削多线切割表面完整性研究

游离磨料多线切割是目前加工太阳能硅片的主要方法。然而,该方法切痕较深,损伤层较厚,进一步增大硅片尺寸、减小硅片厚度难度很大。游离磨料电解磨削多线切割,复合了机械磨削和电化学加工方法,通过在加工过程中给硅锭和切割线施加电场产生阳极钝化或腐蚀,可以有效降低切割负载,提高切割效率,改善硅片的表面质量。以156 mm×56 mm(8寸)、电阻率(1~3?·cm)P型多晶硅片切割为例,初步试验结果表明,采用相同的切割参数和原材料,相对于游离磨料多线切割,电解磨削多线切割硅片的弯曲度降低了3μm,分布区间集中在0~9μm之间;采用20%的Na OH溶液腐蚀硅片,表面的隐裂和深沟槽较少出现,说明硅片的表面损伤程度减轻,有利于减少后续制绒减薄量。该方法和现有游离或固结磨料多线切割技术兼容性好,设备改造成本低,工程应用前景十分广阔。     

Research on chemo-mechanical grinding of large size quartz glass substrate

Finishing process of quartz glass substrate is meeting great challenges to fulfill the requirements of photomask for photolithography applications. For the final finishing of the substrate surface, chemical mechanical polishing (CMP) is often utilized. Those free abrasive processes are able to offer a great surface roughness, but sacrifice profile accuracy. On the other hand, the fixed abrasive process or grinding is known as a promising solution to improve accuracy of profile geometry, but always introduces damaged layer. Chemo-mechanical grinding (CMG) is potentially emerging defect-free machining process which combines the advantages of fixed abrasive machining and CMP. In order to simultaneously achieve high surface quality and high profile accuracy, CMG process has been applied into machining of large size quartz glass substrates for photomask use. Reported in this paper are CMG performances in finishing of quartz glass substrates including material removal rate (MRR), surface roughness, flatness and optical characteristics.     

Grinding-aided electrochemical discharge machining of particulate reinforced metal matrix composites

A grinding-aided electrochemical discharge machining (G-ECDM) process has been developed to improve the performance of the conventional ECDM process in machining particulate reinforced metal matrix composites (MMCs). The G-ECDM process functions under a combined action of electrochemical dissolution, spark erosion, and direct mechanical grinding. The tool electrode has a coating containing a hard reinforcement phase of diamond particles. The MMC employed in this study was Al₂O₃ particulate reinforced aluminum 6061 alloy. The material removal mechanism of this hybrid process has been analyzed. The results showed that the grinding action can effectively remove re-cast material deposited on the machining surface. The surface roughness (R _a) measured for the G-ECDM specimen was ten times smaller than that of the specimen machined without grinding aid (i.e., ECDM alone). Moreover, the material removal rate (MRR) of G-ECDM was about three times higher than that of ECDM under the experimental conditions of this study. The voltage waveform and crater distribution were also analyzed, and the experimental results showed that the G-ECDM process operates in a stable condition. The relative importance of the various processing parameters on MRR was established using orthogonal analysis. The results showed that MRR is influenced by the machining parameters in the order of duty cycle?>?current?>?electrolyte concentration. This study showed that the G-ECDM process is superior to the ECDM process for machining particulate reinforced MMCs, where a higher machining efficiency and a better surface quality can be obtained.     

硬脆材料旋转超声加工技术的研究现状及展望

旋转超声加工是一种复合特种加工技术,它复合了传统超声加工和普通磨削加工的材料去除方式,在提高硬脆材料去除效率、减小切削力、提高加工精度和表面完整性等方面具有显著优势。自旋转超声加工技术发明至今,国内外学者开展了大量的有关旋转超声加工装备及工艺的研究工作,并且已在几乎所有主要的硬脆难加工材料中得到实际应用。本研究在简要概述旋转超声加工技术的基本原理和发展过程基础上,总结国内外学者在材料去除机理、工艺特性、加工新形式以及装备研发等几方面的主要研究成果,并对旋转超声加工技术的发展趋势及值得关注的问题进行展望。