SiCp/Al复合材料旋转超声辅助磨削的试验研究

铝基碳化硅颗粒增强复合材料(SiCp/Al)有许多优异的特性,但其加工非常困难,限制了该种材料在工程中的应用。旋转超声辅助磨削加工非常适合中、高体分SiCp/Al复合材料的加工。针对增强体体积分数45%、增强颗粒尺寸3μm、基体材料A12的SiCp/Al复合材料进行了实验研究,分析了加工表面形貌、表面粗糙度和切削力随切削参数的变化规律。实验结果表明,工件加工表面质量较高,表面粗糙度Ra值在0.131~0.340μm之间;切削过程平稳,轴向切削力Fz值在23.33~51.31N。     

SiCp/Al轴向超声振动微铣削的切削特性试验研究

针对SiCp/Al复合材料微铣削刀具易磨损、难以获得高质量加工表面的问题,对40%体积分数的SiCp/Al复合材料采用轴向超声振动进行辅助微铣削,根据轴向超声振动微铣削的切削特点,通过试验研究铣削力信号的幅频特性,三向切削力随主轴转速、切削深度和每齿进给量的变化规律,并与普通微铣削进行和对比。结果表明:采用轴向超声振动辅助微铣削,三向铣削分力都呈现出随主轴转速先增大再缓慢减小的趋势,可使3个方向的铣削力减小10%～50%。     

SiCp/Al复合材料铣削加工工艺参数的优化实验研究

SiC颗粒增强铝基复合材料(SiCp/Al复合材料)因具有优良的力学性能而在航天航空、汽车等领域应用广泛.现采用硬质合金立铣刀在五轴联动加工中心对SiCp/Al复合材料进行铣削加工,通过正交试验,分析了主轴转速、进给量、切削深度对铣削力、表面粗糙度的影响;从材料去除率、加工表面质量等方面考虑,得到了所选参数范围内较优的铣削加工工艺参数组合:主轴转速5000 r/min,切削深度1 mm,进给量0.02 mm/z.     

旋转超声钻削的切削力数学模型及试验研究

通过分析硬脆材料脆性断裂去除机理和旋转超声加工特点,确定旋转超声加工时单颗磨粒的切削时间、切削深度、切削速度及切削轨迹长度,建立旋转超声恒进给率钻削硬脆材料的切削力数学预测模型。光学玻璃加工试验研究表明,切削力随进给速度的增大而增大,随主轴转速的提高而减小;在高进给速度条件下,切削力对主轴转速的变化更为敏感,在低主轴转速条件下,切削力对进给速度的变化更为敏感;从而很好地验证了已建立的切削力数学预测模型。旋转超声加工和普通加工的对比试验表明,旋转超声钻削加工可以有效降低切削力,一定程度上减小出孔崩边尺寸,从而提高加工效率、降低加工成本。根据旋转超声加工的表面粗糙度值略高于普通加工,提出硬脆材料脆性断裂去除时磨粒实际切削深度决定加工表面粗糙度的判断。     

SiCp/Al复合材料在常规与超声振动辅助条件的切削过程和表面形成的有限元分析

SiCp/Al复合材料是一种典型的难加工的材料,由于其基体中颗粒增强导致常规切削中加工质量差、切削阻力高、加工损伤高,机械加工性差,常规切削已不能满足加工要求。通过切削仿真,对比分析常规与超声振动辅助切削条件下复合材料的切削过程、SiC颗粒的损伤特性、工件的表面形貌与亚表面损伤。结果表明,相比于常规切削,超声振动辅助切削可以提高复合材料的表面完整性,减少复合材料的亚表面损伤,并且能够提高工件的表面质量。     

PCD纤维刀具切削碳化硅颗粒增强铝合金的试验研究

碳化硅颗粒增强铝基复合材料(SiCp/Al复合材料)因其优良的综合性能,在航天航空、汽车等领域应用广泛,然而硬质颗粒的加入给加工带来了很大困难.现采用PCD纤维刀具进行SiCp/Al复合材料的切削实验,通过Kister测力仪对切削力作在线测量,采用扫描电镜对加工表面形貌进行了显微观察,分析了进给速度、切削深度对切削力、表面质量的影响.结果表明:由于PCD纤维刀具加工最大未变形切削层厚度小,因而切削力小;当切削深度小于0.5 mm,进给量小于75 mm/s时,能获得较好的加工表面质量.     

高体分SiC/Al复合材料微磨削表面粗糙度试验研究

SiC/Al复合材料是一种以铝为基体,碳化硅为增强颗粒的复合材料。由于材料的高硬度特性,导致已加工表面出现裂纹和磨损等现象,采用PCD刀具对SiC/Al2024进行微磨削试验,基于响应曲面法,设计实验数据,根据试验结果,建立主轴转速、进给速度和切削深度的回归方程。通过响应曲面图,分析主轴转速、进给速度和切削深度交互作用对表面粗糙度的影响程度,其从大到小依次为:主轴转速、切削深度和进给速度。主轴转速和进给速度交互影响显著,获得最小粗糙度为0.51μm。     

超声振动铣削陶瓷基复合材料切削力模拟研究

针对陶瓷基复合材料在加工过程中易出现毛刺、分层、崩边等加工问题,提出超声振动切削方法加工陶瓷基复合材料并进行了铣削过程的有限元模拟分析。给出了主轴转速、进给速度对铣削过程中各向切削力的影响,对比分析了超声振动铣削加工与普通铣削加工的切削力波形曲线。结果表明,两种加工方法各向切削力均随主轴转速的增大而减小,进给速度的增大而增大,但当主轴转速达到4000r/min时,超声作用消失,超声振动切削力与普通铣削切削力相当;同时,超声振动铣削加工条件下各向切削力峰值都明显低于普通铣削切削力,平均切削力更是有大幅度降低,超声振动切削方法更适合加工陶瓷基复合材料。     

石英玻璃旋转超声铣削表面质量研究

探索了高频旋转超声铣削石英玻璃的工艺规律与材料去除机理,检测分析了加工表面粗糙度与表面形貌,借助Matlab平台建模仿真了进给速度和主轴转速对磨粒运动轨迹的影响规律,研究了进给速度、主轴转速、切削宽度以及切削深度对加工表面质量的影响规律与机理。进给速度增大会导致刀具上的单颗金刚石磨粒的切削速度增大,参与切削的摆线平面投影运动轨迹变长,使表面粗糙度随进给速度增加先增大后减小;表面粗糙度值随主轴转速的增大总体上呈现出先减小后增大的趋势,主轴转速为3 000 r/min时铣削表面粗糙度最小;表面粗糙度值随切削宽度增大先增大后减小,切削宽度直接决定相邻刀具路径对应加工区域重叠范围,进而产生不同的磨粒划刻加工叠加效果;随切削深度增大,表面粗糙度值呈现出先增大后减小再增大的趋势,铣削过程中超声振动与切削深度配合产生的近成形表面材料去除模式对表面质量具有关键性作用。研究工作可为石英玻璃旋转超声铣削加工提供一定的工艺基础。     

SiC_p/Al复合材料高速铣削加工表面质量及切屑形成机制

使用聚晶金刚石(PCD)刀具,对碳化硅颗粒增强铝基复合材料(SiCp/Al)进行高速铣削加工,研究了加工表面质量及切屑的形成机制。结果表明:刀具进给波纹、工件材料塑性侧流、刀具-工件相对振动和增强颗粒去除过程留下的孔洞、微裂纹、基体撕裂等是SiCp/Al复合材料高速铣削加工表面的主要形成机制;增大切削速度、使用冷却液、降低增强颗粒体积分数、减小增强颗粒尺寸均有助于提高加工表面质量;切屑形态为不均匀锯齿状,增强颗粒体积分数、热处理状态等对切屑形成有显著影响,绝热剪切、孔洞/微裂纹动态形成和扩展是切屑的主要形成机制。     

超声振动钻削SiC颗粒增强铝基复合材料时的切削力研究

采用超声振动钻削的方法对金属基复合材料进行孔加工。在自行研制的超声钻削设备的基础上使用不同材质的硬质合金麻花钻,对不同含量的SiC颗粒增强铝基复合材料(SiCp/Al)进行了普通钻削与超声振动钻削的对比试验,并分析比较了加工中切削力的变化规律。试验表明,超声振动钻削可以降低切削力,在一定程度上改善钻削机理。     

Effect of machining parameters on the milling process of 2.5D C/SiC ceramic matrix composites

Abstract

The C/SiC ceramic matrix composites are widely used for high-value components in the nuclear, aerospace and aircraft industries. The cutting mechanism of machining C/SiC ceramic matrix composites is one of the most challenging problems in composites application. Therefore, the effects of machining parameters on the machinability of milling 2.5D C/SiC ceramic matrix composites is are investigated in this article. The related milling experiments has been carried out based on the C/SiC ceramic matrix composites fixed in two different machining directions. For two different machining directions, the influences of spindle speed, feed rate and depth of cut on cutting forces and surface roughness are studied, and the chip formation mechanism is discussed further. It can be seen from the experiment results that the measured cutting forces of the machining direction B are greater than those of the in machining direction A under the same machining conditions. The machining parameters, which include spindle speed, feed rate, depth of cut and machining direction, have an important influence on the cutting force and surface roughness. This research provides an important guidance for improving the machining efficiency, controlling and optimizing the machined surface quality of C/SiC ceramic matrix composites in the milling process.     

金刚石磨头刀具磨铣加工对高体份SiCp/Al复合材料加工表面质量的影响

针对高体份SiCp／Al复合材料,采用佥刚石磨头刀具磨铣切削的加工方法,研究了高速磨铣加工中机床主轴转速、工件进给速度及背吃刀量对材料加工表面形貌损伤以及表面粗糙度的影响规律。研究表明,机床主轴转速的提高、工件进给速度的减小都能够减小材料表面形貌的损伤情况,改善加工表面粗糙度质量：背吃刀量的改变对材料表面形貌损伤以及表面粗糙度的影响不大。     

第一切削变形区中SiC增强相的重定向研究

介绍了切削SiC非连续增强铝基复合材料时第一切削变形区的材料变形情况,推导了SiC增强相的转角公式,并用试验结果验证了SiC增强相的重定向现象。结果表明,第一切削变形区中的SiC增强相发生了重新定向运动,转向了铝基体的纤维化方向,转角大小会因SiC增强相在第一切削变形区中的具体位置和原位向的不同而存在差异。SiC增强相重定向后并不与剪切面重合,而是成一定角度。第一切削变形区的宽度与切削铝基体材料相比要大。     

ROTARY ULTRASONIC MACHINING OF CARBON FIBER-REINFORCED POLYMER: FEASIBILITY STUDY

Carbon fiber-reinforced polymer (CFRP) has been widely used in aircraft components, automotive parts, and sporting goods. Hole machining is the most frequently employed operation of secondary machining for fiber-reinforced composites. However, challenges (delamination, splintering, burr, short tool life, low machining precision, and low surface quality) still remain for their widespread applications. Rotary ultrasonic machining (RUM) is a non-conventional machining process that has been used to drill holes in composite materials. However, it has not been used to drill this type of CFRP. In this article, RUM is introduced into drilling holes in this type of CFRP for the first time. The feasibility to machine carbon fiber-reinforced epoxy using RUM is investigated experimentally. Chips, edge chipping, surface roughness, tool wear, and thrust force were measured. Effects of RUM process variables (rotation speed, vibration amplitude, and feedrate) on thrust force and surface roughness were studied. Results showed that RUM could be used to drill holes in CFRP with high productivity and low tool wear. A better surface was produced by higher rotation speed and lower feed rate.     

Prediction of cutting force, tool wear and surface roughness of Al6061/SiC composite for end milling operations using RSM

The results of mathematical modeling and the experimental investigation on the machinability of aluminium (Al6061) silicon carbide particulate (SiCp) metal matrix composite (MMC) during end milling process is analyzed. The machining was difficult to cut the material because of its hardness and wear resistance due to its abrasive nature of reinforcement element. The influence of machining parameters such as spindle speed, feed rate, depth of cut and nose radius on the cutting force has been investigated. The influence of the length of machining on the tool wear and the machining parameters on the surface finish criteria have been determined through the response surface methodology (RSM) prediction model. The prediction model is also used to determine the combined effect of machining parameters on the cutting force, tool wear and surface roughness. The results of the model were compared with the experimental results and found to be good agreement with them. The results of prediction model help in the selection of process parameters to reduce the cutting force, tool wear and surface roughness, which ensures quality of milling processes.     

PCD刀具超声振动车削SiC_p/Al复合材料时的切削力特性研究

用PCD刀具对SiCp/Al复合材料进行了超声振动车削与普通车削的对比试验 ,探讨了切削速度、进给量和切深三种切削参数在两种切削状态下对切削力的影响规律 ,得出了超声振动车削SiCp/Al复合材料的主切削力经验公式。     

Face Grinding Surface Quality of High Volume Fraction SiCp/Al Composite Materials

The existing research on SiCp/Al composite machining mainly focuses on the machining parameters or surface morphology.However,the surface quality of SiCp/Al composites with a high volume fraction has not been extensively studied.In this study,32 SiCp/Al specimens with a high volume fraction were prepared and their machining parame-ters measured.The surface quality of the specimens was then tested and the effect of the grinding parameters on the surface quality was analyzed.The grinding quality of the composite specimens was comprehensively analyzed taking the grinding force,friction coefficient,and roughness parameters as the evaluation standards.The best grinding parameters were obtained by analyzing the surface morphology.The results show that,a higher spindle speed should be chosen to obtain a better surface quality.The final surface quality is related to the friction coefficient,surface roughness,and fragmentation degree as well as the quantity and distribution of the defects.Lower feeding amount,lower grinding depth and appropriately higher spindle speed should be chosen to obtain better surface quality.Lower feeding amount,higher grinding depth and spindle speed should be chosen to balance grind efficiently and surface quality.This study proposes a systematic evaluation method,which can be used to guide the machining of SiCp/Al composites with a high volume fraction.     

Cusp error reduction under high speed micro/meso- scale milling with ultrasonic vibration assistance

In the conventional use of vibration assisted machining, vibratory motion is mostly applied to the continuous machining processes such as turning where the cutting speed is much lower than the vibration speed. Even the recent articles on vibration assisted milling processes are also quite limited to low spindle speed less than 3k RPM. This study investigates vibration assistance that is applied to the workpiece in a high speed micro/meso-scale intermittent milling system where the cutting speed is much higher than the vibration speed. In addition to this, the vibration effect is analyzed considering feed and cross-feed directional application separately, which gives an idea of a right vibration assistance direction for surface quality improvement. To validate this, a one-directional ultrasonic vibration assisted milling system with ultrasonic frequency at 40 kHz and with amplitudes of a few microns is designed and its effect on the machined surface quality is investigated at high spindle RPMs over 15k. As a result, cusp heights are found to be reduced with ultrasonic vibratory motion of cutting edge in high cutting speed. Furthermore, the machined surface quality clearly tells that feed directional vibration assistance is able to generate better surface quality with reduced wavy burrs than cross-feed directional vibration assistance.