微铣削切削力特性及表面质量的实验研究

为了研究微铣削加工过程中切削用量对切削力的影响规律及加工质量,采用直径150μm的硬质合金微铣刀进行了微铣削加工实验.一方面,采用单因素实验方法,研究了铣削微槽时主轴转速、轴向切削深度和每齿进给量对切削力的影响规律,实验发现主轴转速和轴向切削深度是影响切削力的重要因素,而每齿进给量的影响最小.以每齿进给量与切削刃刃口半径的比值fz/Re为变量,研究了切削比能的尺寸效应现象,发现随着fz/Re的减小,切削比能增大,当fz/Re1.0以后,切削比能急剧增大.另一方面,从毛刺宽度和表面粗糙度两个方面研究了fz/Re对微铣削加工质量的影响规律,其结果表现出明显的尺寸效应现象,随着每齿进给量的的减小,毛刺宽度和表面粗糙度均先减小后增大.当fz/Re=0.5时毛刺最小;当fz/Re=1.0时,表面粗糙度最小.本研究可以为实际加工中合理选择切削用量以及分析微铣削尺寸效应现象提供理论依据.     

微观状态SiCp/Al复合材料铣削残余应力模拟分析

为了获得更高精度的高体积分数SiCp/Al复合材料铣削加工表面残余应力数据,采用有限元分析软件ABAQUS建立了基于正交切削的微观平面应变模型。复合材料两相材料属性被分别定义,改善了在宏观状态下整体定义材料属性的精度缺陷,并对其微观状态切削残余应力产生过程进行模拟分析。分析并得出了不同切削参数对工件加工表面残余应力的影响规律以及沿工件层深方向的残余应力分布情况。结果表明切削速度和每齿进给量对SiCp/Al复合材料已加工表面残余应力有着相似的影响规律,但每齿进给量的影响作用较为显著。     

多齿铣刀侧铣加工多层CFRP铣削力的建模与仿真

由于碳纤维增强树脂基复合材料(CFRP)的层间结合强度较低,进行切削加工时在切削力的作用下容易出现分层和毛刺等质量缺陷。因此,通过对切削力的预测与控制可以有效提高加工质量。采用瞬时刚性力模型对多齿铣刀侧铣多层CFRP材料的加工过程进行铣削力建模与仿真,分析了多齿铣刀特有的几何结构对切削力的影响。试验中保持切削速度恒定,以不同进给速度分别对45°、0°、-45°和90°这4种典型纤维方向的单向CFRP进行侧铣加工,通过测得的切削力数据计算各自的铣削力系数。根据力学矢量叠加原理得到了多向CFRP铣削力系数的简化计算表达式,最后将计算结果代入铣削力模型得到了各时刻的铣削力仿真值。在同样的试验条件下对该多向CFRP进行侧铣加工验证试验,试验结果表明: 该模型能较好地预测铣削力,最大相对误差小于9%,平均相对误差小于5%,可为铣削参数优化和刀具结构优化提供理论基础。     

300M超高强度钢车削加工性能仿真模拟分析研究

目的研究不同切削参数对300M超高强度钢切削性能的影响。方法通过单因素试验法,采用Advant Edge切削仿真软件,建立300M钢三维有限元模型,对不同切削参数下车削300M钢的切削力、刀片温度、刀片应力及切屑形状进行分析。结果在300M钢车削过程中,刀片温度随着切削速度增大而增大,但切削力和刀片应力反之;背吃刀量和进给量越小,切削力、刀片应力及刀片温度越小;切削刃半径越小,切削力越小,但小的切削刃半径使得刀片应力变大,容易导致刀片磨损。车削300M钢的切屑呈锯齿螺旋状,切屑温度为带状分布,切削速度越高,进给量、背吃刀量越大,切削刃半径越小,切屑温度越高。结论在300M钢车削加工中,应选用较高的切削速度,适中的切削刃半径,较小的进给量和背吃刀量。     

高温合金GH4169铣削力试验

高温合金是材料加工中典型的难加工材料,在加工过程中,铣削力大,刀具破损严重,给加工生产造成很大影响。本次试验主要针对高温合金GH4169的铣削力进行研究,对正交试验所得数据进行线性回归分析,得到了适用于本次试验设备条件的铣削力经验公式;对试验结果进行极差分析,结果表明:各向铣削力随切深和进给量的增加而增大,随切削速度的增加而减小,并且在铣削参数组合为v=400m/min,ap=0.9mm,fz=0.05mm/z时,各向铣削力取得最小值。     

涂层硬质合金刀具对奥氏体不锈钢的切削特性

为了深入探究涂层硬质合金刀具切削奥氏体不锈钢的切削机理,试验采用确定的进给量和背吃刀量,只改变切削速度的单因素法,来研究切削速度对奥氏体不锈钢工件加工表面质量的影响以及涂层刀具的切削机理。采用JEOL JSM-6360LV扫描电子显微镜和EDS能谱仪对工件加工表面及磨损刀片进行表面微区磨损形貌的观察分析与组成成分分析,采用X射线衍射仪对工件表面物相组成进行分析,采用激光扫描显微镜LSM对工件表面三维形貌进行观察分析。研究表明,切削速度较低时,不锈钢材料因材质较软,断屑性能较差;速度较高时,切削过程中粘着现象严重,致使摩擦剪应力较大,摩擦表面发生形变,进而诱发不锈钢的马氏体相变。因此,宜选用中速V=85m/min进行切削,在此速度下,被加工件获得的表面质量较好,表面粗糙度Ra=3.679μm。刀具磨损主要发生在前刀面靠近刀尖的部位,磨损机理主要表现为粘着磨损。研究发现,涂层硬质合金刀具在体现出一定的良好切削性能的同时也不可避免地发生了磨损,所以深入研究其切削机理能够丰富涂层刀具的切削理论,为提高涂层刀具在切削难加工材料时的刀具寿命以及拓展其在实际切削加工中的应用范围提供试验依据。     

高体积分数SiCp/Al复合材料铣削残余应力有限元模拟

高体积分数碳化硅颗粒增强铝基(SiCp/Al)复合材料具有优良的综合物理力学性能,其难加工性制约着该材料的应用与发展,切削加工产生的表面残余应力严重影响了工件的结构和尺寸精度稳定性。为了研究高体积分数SiCp/Al复合材料的铣削加工表面残余应力,采用有限元分析软件ABAQUS建立了基于正交切削的平面应变模型,并对建立的宏观等效模型进行模拟分析。在模拟结果中,分析并得出了不同切削速度和每齿进给量对工件加工表面残余应力的影响规律以及沿工件层深方向的残余应力分布情况。     

SiCp/Al复合材料薄壁件钻削加工的有限元仿真

本文基于ABAQUS有限元仿真软件,对比研究了SiCp/Al复合材料薄壁件和厚壁工件的钻孔过程及切削力的变化特点,提出了薄壁钻孔的3个特征阶段;同时,通过改变切削参数,对薄壁件的钻削力及最大变形量的变化规律进行了研究。结果表明:在切削速度(或进给量)一定的条件下,随着刀具进给量(或切削速度)的增加,轴向力和钻削扭矩大体呈线性增加趋势;切削速度对薄壁钻孔变形影响不大,进给量对薄壁钻孔变形的影响较切削速度显著,薄壁件的最大变形量随进给量的增加而增大。     

SiCP/2024复合材料切削力与刀具磨损的试验研究

本文通过SiC_P/2024复合材料的车削试验,得出了刀具材料、切削用量及SiC_P含量对切削力和刀具磨损的影响规律。并认为K类硬质合金可用于粗加工和半精加工,而且要采用较低切削速度和较大进给量,但SiC_P含量较高时会出现切深分力大于主切削力。SiC_P含量越高差值越大;PDC是精加工最佳刀具材料,也不会出现切深分力大于主切削力现象     

高速铣削22SiMn2TiB高强度钢的铣削力建模与试验研究

通过涂层硬质合金刀片对22SiMn2TiB高强度钢进行四因素四水平的正交铣削试验,采集切削力信号,对试验数据进行方差分析(ANOVA),得到了切削参数对铣削力影响的规律.通过多元线性回归建立了两个铣削力预测经验模型——二次模型和指数模型,并进行了模型的显著性分析,发现二次模型优于指数模型,指数模型对Fz的拟合效果差.     

Studies on Machining Parameters While Milling Particle Reinforced Hybrid (Al6061/Al2O3/Gr) MMC

In this article, response surface methodology has been used for finding the optimal machining parameters values for cutting force, surface roughness, and tool wear while milling aluminum hybrid composites. In order to perform the experiment, various machining parameters such as feed, cutting speed, depth of cut, and weight (wt) fraction of alumina (Al₂O₃) were planned based on face-centered, central composite design. Stir casting method is used to fabricate the composites with various wt fractions (5%, 10%, and 15%) of Al₂O₃. The multiple regression analysis is used to develop mathematical models, and the models are tested using analysis of variance (ANOVA). Evaluation on the effects and interactions of the machining parameters on the cutting force, surface roughness, and tool wear was carried out using ANOVA. The developed models were used for multiple-response optimization by desirability function approach to determine the optimum machining parameters. The optimum machining parameters obtained from the experimental results showed that lower cutting force, surface roughness, and tool wear can be obtained by employing the combination of higher cutting speed, low feed, lower depth of cut, and higher wt fraction of alumina when face milling hybrid composites using polycrystalline diamond insert.     

Experimental Study of Cutting Force,Microhardness, Surface Roughness,and Burr Size on Micromilling of Ti6Al4V in Minimum Quantity Lubrication

In the present study, the effects of various cutting conditions on the surface integrity of titanium parts (Ti6Al4V) have been investigated during the micromilling process. In addition, to have a better understanding of the results, the cutting force was measured. The experiments were performed in the Minimum Quantity Lubrication condition using the tungsten carbide microtool with 0.5 mm in diameter. Micromilling parameters including feed rate, spindle speed and axial depth of cut were considered as process inputs, each in three levels, and their effects on the surface roughness, burr width, surface and in-depth microhardness as well as mean cutting force were evaluated. In the range of experimental parameters and according to the results, cutting speed and feed per tooth had the highest impact on the surface integrity characteristics of this alloy, respectively. While most research works concentrated on the feed per tooth as the main parameter in the micromilling process, the result of the study showed that the variation of cutting speed as one of the influential factors could also be used in order to decrease cutting forces and to improve surface quality.     

Residual Stress and Affected Layer in Disc Milling of Titanium Alloy

Disc milling is used in manufacturing, especially for difficult-to-machine material such as titanium alloy, because of its strong force and high machining efficiency. However, research on the cutting mechanism of the disc-milling technique is still lacking in the literature. In the present study, first, a disc-milling grooving experiment was designed and carried out to test the milling temperature correlated to the milling force for titanium alloy samples. After machining, residual stress, microstructure and microhardness were investigated. Residual compressive stress was found on the milling surface, which changes to tensile stress gradually with the increase of depth. The impact of cutting factors on residual stress was also analyzed numerically and the results showed that with the increase of speed of the mainshaft, the residual stress reduced gradually. For the factors of depth of cut and feed speed, increasing them had the opposite effects on residual stress. Next, the microstructures of lattice tensile deformation and lattice fracture were observed under different cutting conditions. The metallographic structure changed on increasing the milling temperature, progressing from an initial equiaxed microstructure to an α + β duplex microstructure, and then formed a lamellar microstructure later. The microhardness in the plastic deformation zone was also taken into account, which showed that the hardness increased under the combined effect of the milling temperature and force.     

Experimental Analysis of Cutting Forces in Microdrilling of Austenitic Stainless Steel (X5CrNi18-10)

This article presents an experimental investigation on microdrilling of austenitic stainless steel which is a difficult material for machining because of its properties like high strain-hardening rate, low thermal conductivity, and high fracture toughness. Microholes are produced on X5CrNi18-10 austenitic stainless steel workpiece using 0.5 mm diameter solid carbide microdrills. Two factors (cutting speed and feed) and three levels (low–center–high) full-factorial design of experiment are performed. Response surface methodology is used to developed mathematical models (quadratic and bilinear regression models) for cutting forces in microdrilling. The experimental analysis shows that feed affects the cutting force components (radial and thrust) significantly. Additionally, it also shows that there are only minor effects from cutting speed, square of cutting speed, square of feed and product of speed, and feed on the cutting forces. Finally, the optimized cutting conditions are proposed for minimum cutting forces.     

Milling performance of stone-plastic composite with diamond cutters

In order to meet the requirements of cutting efficiency and economy in the processing of stone plastic composite, milling tests of the stone plastic composite were conducted using straight tooth diamond tools. Cutting forces and temperature were measured under different cutting parameters. Response surface methodology was used to analyze the variation of cutting forces and temperature and to determine the significant contribution of each variable and its two-level interaction. The correlation between actual and predicted results was found by building mathematical models of cutting forces and temperatures, which can be used to make accurate predictions. At last, the optimal cutting parameters for stone plastic composite straight-tooth milling with low cutting forces and cutting temperatures were found to be 10° front angle, 37.9 m/s cutting speed, 0.32 mm feed per tooth, and 0.5 mm milling depth. It is possible to improve processing efficiency and reduce production costs by using these parameters in industrial processing.     

Experimental study on the meso-scale milling of tungsten carbide WC-17.5Co with PCD end mills

Tungsten carbide is a material that is very difficult to cut, mainly owing to its extreme wear resistance. Its high value of yield strength, accompanied by extreme brittleness, renders its machinability extremely poor, with most tools failing. Even when cutting with tool materials of the highest quality, its mode of cutting is mainly brittle and marred by material cracking. The ductile mode of cutting is possible only at micro levels of depth of cut and feed rate. This study aims to investigate the possibility of milling the carbide material at a meso-scale using polycrystalline diamond (PCD) end mills. A series of end milling experiments were performed to study the effects of cutting speed, feed per tooth, and axial depth of cut on performance measures such as cutting forces, surface roughness, and tool wear. To characterize the wear of PCD tools, a new approach to measuring the level of damage sustained by the faces of the cutter's teeth is presented. Analyses of the experimental data show that the effects of all the cutting parameters on the three performance measures are significant. The major damage mode of the PCD end mills is found to be the intermittent micro-chipping. The progress of tool damage saw a long, stable, and steady period sandwiched between two short, abrupt, and intermittent periods. Cutting forces and surface roughness are found to rise with increments in the three cutting parameters, although the latter shows signs of reduction during the initial increase in cutting speed only. The results of this study find that an acceptable surface quality (average roughness R_a<0.2 μm) and tool life (cutting length L>600 mm) can be obtained under the conditions of the given cutting parameters. It indicates that milling with PCD tools at a meso-scale is a suitable machining method for tungsten carbides.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00298-y     

Experimental Study of Surface Roughness and Tool Flank Wear during Hybrid Milling

Two advanced machining methods such as thermally enhanced machining and ultrasonic-assisted machining are recently considered in many studies. In this article, a new hybrid milling process is presented by gathering the characteristics of these two methods. In order to determine the axial depth of cut and engagement in the process, three-dimensional thermal finite-element analysis is applied to determine the dimensions of softened materials. Finite-element modal analysis is used to determine the dimensions and clamping state of the workpiece while cutting area has the highest vibration amplitude. Full factorial experimental design is applied to investigate the effect of hybrid machining parameters on the surface roughness and tool wear. Tool flank wear was investigated under the condition of constant cutting speed during different period of times. Hybrid milling process with an amplitude of 6 µm and a temperature of 900°C creates a surface with 42% lower roughness in comparison to conventional milling in feed 0.08 mm/tooth. In a study of tool flank wear, the results show that application of TEUAM decreases flank wear at least 16% in comparison to all other processes.     

Surface Defects in Groove Milling of Hastelloy-C276 Under Fluid Coolant

This study aims to investigate surface integrity in groove milling of Hastelloy-C276 using coated carbide end mills under the application of water-based fluid coolant using different cutting parameters. Surface integrity was assessed by measuring surface roughness, using focus variation microscope, and investigating surface defects, using scanning electron microscope. Micro-chips re-deposition and long grooves dominated the machined surface at low cutting speed (24–50 m/min). While cracked and fractured re-deposited materials, grooves, large debris, and plastic flow dominated the machined surface at high cutting speed (70–120 m/min), consequently surface roughness increased with cutting speed. Nucleated cavities appeared at all cutting speeds but with different densities. Shallow depth of cut at low cutting speed gave negative effect on surface roughness due to the effect of the hardened layer. Overall, the best surface finish, with average roughness below 50 nm and minimum surface abuse, was obtained in the speed range of 24–50 m/min at feed rate of 1 µm/tooth and depth of cut deeper than 0.1 mm.     

Prediction of cutting force based on machining parameters on AL7075-T6 aluminum alloy by response surface methodology in end milling

Cutting forces modeling is the basic to understand the cutting process, which should be kept in minimum to reduce tool deflection, vibration, tool wear and optimize the process parameters in order to obtain a high quality product within minimum machining time. In this paper a statistical model has been developed to predict cutting force in terms of geometrical parameters such as rake angle, nose radius of cutting tool and machining parameters such as cutting speed, cutting feed and axial depth of cut. Response surface methodology experimental design was employed for conducting experiments. The work piece material is Aluminum (Al 7075-T6) and the tool used is high speed steel end mill cutter with different tool geometry. The cutting forces are measured using three axis milling tool dynamometer. The second order mathematical model in terms of machining parameters is developed for predicting cutting forces. The adequacy of the model is checked by employing ANOVA. The direct effect of the process parameter with cutting forces are analyzed, which helps to select process parameter in order to keep cutting forces minimum, which ensures the stability of end milling process. The study observed that feed rate has the highest statistical and physical influence on cutting force.     

镍基铸造高温合金K24的切削温度实验研究

通过实验,分析了使用YW1刀具切削K24时,切削用量对切削温度的影响。对切削温度影响最大的是切削速度,但是,随着切削速度的增加切削温度的增加量是下降的。这是因为在切削过程中,速度的增加使得副后刀面磨损加剧,切削深度减小,切削力减小,切削温度也随着相对降低。切削用量对切削温度的影响其次是进给量,影响最小的是切削深度。通过实验所得的切削用量与切削温度的经验公式,将这3个公式合并可得到切削用量对切削温度的总的经验公式。