润滑条件对TC4钛合金切削加工影响的实验研究

为了研究冷却润滑条件及切削参数对TC4钛合金的切削力和表面粗糙度的影响,分别开展CMQL、冷风、浇注式冷却润滑条件的TC4钛合金高速切削实验、四种不同润滑环境的粗/半精/精加工实验以及CMQL条件下TC4钛合金正交切削试验,通过单因素分析和正交试验法研究冷却润滑条件及切削参数对切削加工性的影响。研究表明：CMQL冷却润滑条件可在TC4钛合金高速切削时有效降低切削阻力和改善表面粗糙度,并在高速精车削阶段体现出降低切削阻力的优势。考虑CMQL条件下高速精车TC4钛合金加工效率,最佳参数组合为较高的切削速度、较小的精加工余量和合适范围内较大的进给量。     

钛合金车削切削力及表面粗糙度优化分析

采用TC11钛合金车削正交试验研究了各车削参数对切削温度和切削力的影响规律,进一步分析车削参数和表面粗糙度的内在联系。结果表明：切削温度与切削力相互影响,当切削速度在50～100m/min时,切削速度越高,刀具对工件挤压越剧烈,且切削温度升高并使工件软化,导致切削力减小。通过极差分析发现,影响切削力的切削参数依次为切削深度>进给量>切削速度,影响切削温度的切削参数依次为切削速度>进给量>切削深度;对于表面粗糙度各切削用量影响程度大小依次为进给量>切削速度>切削深度。在本次试验参数内,得到了最优切削力的切削参数和最优表面粗糙度的切削参数。研究结果对于加工钛合金的切削参数优化提供一定指导。     

基于DEFORM-3D的钛合金切削过程有限元仿真

为研究钛合金TC4的切削机理,建立了三维切削有限元模型并对切削过程进行了仿真,获得了不同每齿进给量、切削速度和切削深度下切削力、切削温度的变化规律。仿真结果表明：在各因素中,对切削温度而言,切削速度影响最大,切削深度影响最小;对切削力而言,切削速度影响最小,切削深度影响最大。     

液氮冷却下大进给铣削TC4钛合金的试验研究

钛合金是现代飞行器的主要结构材料之一,是一种典型的难加工材料。针对切削加工钛合金时刀具磨损快、表面质量不易控制等难题,将TC4钛合金作为研究对象,以液氮作为冷却介质,进行了TC4钛合金的大进给铣削试验,测试了液氮冷却条件下大进给铣削TC4钛合金的铣削力、铣削温度以及刀具磨损等,并与乳化液和低温冷风条件下的测试结果进行了对比分析。结果表明:在以较大的切削速度和每齿进给量铣削TC4钛合金时,采用液氮冷却比使用乳化液能更有效地降低切削力和切削温度;比采用低温冷风冷却能更有效地延长刀具寿命。     

[刀具及切削工艺]典型钛合金TC17车削过程鳞刺生成规律及其抑制措施

为研究钛合金车削过程中鳞刺生成规律及有效抑制措施,分析了影响鳞刺生成的主要因素,采用弯矩法解析了鳞刺折断规律,进而建立了切削参数、刀具几何参数与刀尖弯矩的数学描述模型;通过MATLAB对模型进行求解,获知切削速度对刀尖弯矩的影响最小,而切削深度、进给量、刀尖圆弧以及刀具主偏角4个因素决定了刀尖弯矩的大小。为验证描述模型的正确性,进行了典型钛合金TC17外圆周断续切削实验,采集在恒定切削速度、不同切削深度、不同进给量、不同主偏角及不同刀尖圆弧条件下的鳞刺样本数据,并获得鳞刺折断规律曲线。实验结果表明：在小于临界切削深度和大于临界进给量条件下,实验结果与数学描述模型整体趋势一致,证明了数学描述模型的正确性。研究结果可为钛合金的高品质加工提供工艺技术及刀具优选方面的数据支撑。     

密齿硬质合金涂层刀具铣削TC4钛合金试验研究

利用单因素试验方法进行了密齿硬质合金涂层刀具铣削TC4钛合金试验,研究每齿进给量和切削速度对切削力、切削温度、加工表面粗糙度以及切屑形态的影响。结果表明:切削方向分力F_x、刀轴方向分力F_z随每齿进给量的增大而增大,进给方向分力F_y随每齿进给量的增加变化不大;切削速度小于75m/min时切削力随切削速度的增加下降较为明显;切削速度超过75m/min时切削力变化不大;切削温度受每齿进给量影响较大,且影响程度随进给量的增加而逐渐减小;随着每齿进给量f_z的增大,加工表面粗糙度值先减小后增大;在每齿进给量高于0.04mm/z时,密齿铣刀铣削TC4钛合金得到的切屑为螺卷状,且随每齿进给量的增加,切屑的曲率半径减小,随切削速度的增大,螺卷状切屑的螺距减小。     

典型钛合金TC17车削过程鳞刺生成规律及其抑制措施

为研究钛合金车削过程中鳞刺生成规律及有效抑制措施,分析了影响鳞刺生成的主要因素,采用弯矩法解析了鳞刺折断规律,进而建立了切削参数、刀具几何参数与刀尖弯矩的数学描述模型;通过MATLAB对模型进行求解,获知切削速度对刀尖弯矩的影响最小,而切削深度、进给量、刀尖圆弧以及刀具主偏角4个因素决定了刀尖弯矩的大小。为验证描述模型的正确性,进行了典型钛合金TC17外圆周断续切削实验,采集在恒定切削速度、不同切削深度、不同进给量、不同主偏角及不同刀尖圆弧条件下的鳞刺样本数据,并获得鳞刺折断规律曲线。实验结果表明:在小于临界切削深度和大于临界进给量条件下,实验结果与数学描述模型整体趋势一致,证明了数学描述模型的正确性。研究结果可为钛合金的高品质加工提供工艺技术及刀具优选方面的数据支撑。     

基于干切削与MQL的稀土镁合金铣削性能对比研究

本文在干切削与微量润滑(MQL)条件下对GW63K稀土镁合金开展铣削试验，分析不同铣削参数与冷却条件对GW63K镁合金铣削力和铣削温度的影响规律，并对已加工表面的形貌与表面质量进行研究。结果表明：在两种冷却条件下，增大切削速度和每齿进给量都会导致GW63K镁合金的铣削合力增加，且每齿进给量的影响更为显著；在MQL条件下，镁合金铣削合力较干切削有所上升；稀土镁合金的铣削温度亦随切削速度与每齿进给量的增大而上升；在干切削条件下，稀土镁合金的铣削温度较高。此外，每齿进给量对GW63K镁合金的已加工表面质量影响显著，而MQL有助于降低已加工表面粗糙度，提高表面质量。综上所述，采用MQL冷却方式，同时选取较低的每齿进给量与较高的切削速度，有助于提高GW63K镁合金的铣削性能。     

基于ABAQUS的钛合金铣削力的模拟分析

为了研究钛合金在铣削过程中切削力随着切削参数的变化规律,建立了三维斜角切削有限元模型。通过对材料本构模型,刀—屑接触摩擦模型和切屑分离准则等关键环节建模,采用通用有限元求解器ABAQUS/Ex-plicit对钛合金Ti6Al4V的斜角切削过程进行了模拟,获得了切削速度v、切削深度ap和每齿进给量fz对切削力的变化趋势及影响程度。模拟结果表明:切削力随着切削深度ap和每齿进给量fz的增大而增大,而随着切削速度增大切削力波动很小。切削深度对切削力的影响最大,进给量次之,切削速度对切削力的影响最小。该模型可以为切削参数的合理选择提供参考。     

TC4铣削中超临界CO2混合油膜附水滴的冷却润滑性能

在干切削、超临界CO2（scCO2）以及scCO2与油膜附水滴(OoW)混合三种绿色切削方式下对钛合金进行了铣削试验。通过单因素试验分析了铣削参数和冷却润滑方式对切削力、切削温度、表面粗糙度的影响规律,研究了scCO2与OoW混合冷却方式在钛合金铣削中的冷却润滑性能。结果表明,三种冷却润滑方式下,随着切削速度、每齿进给量和径向切宽的增大,切削力和切削温度均呈现增大趋势;当切削速度进一步增大时,依据高速切削加工理论,切削力和温度有增长变缓和下降的趋势;不同加工参数下,相比干切削和scCO2,scCO2与微量油膜附水滴混合冷却方式能有效减小切削力和降低切削温度,并获得良好的加工表面,具有良好的冷却润滑性能。     

Effect of turning parameters on surface roughness of A356/5% SiC composite produced by electromagnetic stir casting

In the present investigation, A356 alloy 5 wt% SiC composite is fabricated by electromagnetic stir casting process. An attempt has been made to investigate the effect of CNC lathe process parameters like cutting speed, depth of cut, and feed rate on surface roughness during machining of A356 alloy 5 wt% SiC particulate metal-matrix composites in dry condition. Response surface methodology (Box Behnken Method) is chosen to design the experiments. The results reveal that cutting speed increases surface roughness decreases, whereas depth of cut and feed increase surface roughness increase. Optimum values of speed (190 m/min), feed (0.14 mm/rev) and depth of cut (0.20 mm) during turning of A356 alloy 5 wt% SiC composites to minimize the surface roughness (3.15μm) have been find out. The mechanical properties of A356 alloy 5 wt% SiC were also analyzed.     

Modeling and analyzing the effects of air-cooled turning on the machinability of Ti–6Al–4V titanium alloy using the cold air gun coolant system

This study provides the mathematical models for modeling and analyzing the effects of air-cooling on the machinability of Ti–6Al–4V titanium alloy in the hard turning process. A cold air gun coolant system was used in the experiments and produced a jet of compressed cold air for cooling the cutting process. The air-cooling process seems to be a good environment friendly option for the hard turning. In this experimental investigation, the cutting speed, feed rate and cutting depth were chosen as the numerical factor; the cooling method was regarded as the categorical factor. An experimental plan of a four-factor (three numerical plus one categorical) D-optimal design based on the response surface methodology (RSM) was employed to carry out the experimental study. The mathematical models based on the RSM were proposed for modeling and analyzing the cutting temperature and surface roughness in the hard turning process under the dry cutting process and air-cooling process. Tool wear and chip formation during the cutting process were also studied. The compressed cooling air in the gas form presents better penetration of the lubricant to the cutting zone than any conventional coolants in the cutting process do. Results show that the air-cooling significantly provides lower cutting temperature, reduces the tool wear, and produces the best machined surface. The machinability performance of hard turning Ti–6Al–4V titanium alloy on the application of air-cooling is better than the application of dry cutting process. This air-cooling cutting process easily produces the wrinkled and breaking chips. Consequently, the air-cooled cutting process offers the attractive alternative of the dry cutting in the hard turning process.     

PCBN刀具高速切削钛合金切削性能研究

采用PCBN刀具对钛合金TC4进行了高速车削试验,从切削力、工件表面粗糙度和刀具寿命等方面分析了PCBN刀具加工钛合金的切削性能,并与未涂层硬质合金刀具、涂层硬质合金刀具作了比较,证明了在高切削速度、低进给量和小背吃刀量的条件下,PCBN有着较长的刀具寿命。     

SiCp/Al复合材料薄壁件车削力的仿真研究

应用有限元分析软件ABAQUS对Si Cp/Al复合材料薄壁件车削力进行了仿真研究,得到了切削用量对切削力的影响规律,并结合文献的实验成果对相应规律进行了分析。仿真结果表明:在Si Cp/Al复合材料薄壁件车削过程中,随切削速度的增大,三向切削分力(轴向力Fx、径向力Fy、切向力Fz)均增大,但径向力Fy增幅很小;随进给量的增大,三向切削分力都有增大的趋势;随背吃刀量的增大,三向切削分力均显著增大;背吃刀量是影响切削力的主要因素。     

基于DEFORM的整体CBN刀具切削钛合金的有限元分析

利用DEFORM-3D有限元软件对整体CBN刀具车削钛合金进行了三维仿真,采用单因素试验法模拟分析CBN刀具车削钛合金时切削速度、背吃刀量和进给量对切削力和切削温度的影响。仿真结果表明:对切削力影响最大的是背吃刀量,其次是进给量,切削速度的影响最弱。切削温度方面,切削速度对其影响最大,背吃刀量最小。     

绿色切削SiCp／Al复合材料的刀具温度研究

采用嵌埋人工热电偶的方法,通过正交试验研究了干切削SiCp／Al复合材料时切削参数对刀具前、后刀面切削温度的影响。选定切削参数,实验研究了干式切削、压缩空气风冷、油液浇注和MQL等冷却方式对前、后刀面切削温度的影响。试验结果表明,对于车削SiCp／Al复合材料,后刀面温度高于前刀面温度,进给量对刀具温度影响最显著,MQL切削条件下刀具温度最低。     

Experimental investigation of surface roughness and cutting ratio in a spraying cryogenic turning process

Abstract

Surface roughness is one of the most common criteria indicating the surface finish of the part, which depends on various factors including cutting parameters, geometry of the tool, and cutting fluid. One of the goals of using cutting fluids in machining processes is to achieve improved surface finish. In addition to high costs, commonly used cutting fluids cause dermal and respiratory problems to the operators as well as environmental pollution. The present article aims at investigating the effect of spray cryogenic cooling via liquid nitrogen on surface roughness and cutting ratio in turning process of AISI 304 stainless steel. Through conducting experimental tests, the effects of cutting speed, feed rate, and depth of cut on surface roughness and cutting ratio have been compared in dry and cryogenic turning. A total number of 72 tests have been carried out. Results show that cryogenic turning of AISI 304 stainless steel reduces surface roughness 1%–27% (13% on the average), compared to dry turning. The obtained results showed that the cutting ratio in cryogenic turning is averagely increased by 32% in comparison with dry turning, also that chip breakage is improved in cryogenic turning.     

钛合金TC4高速切削温度场数值仿真

利用专用有限元切削仿真软件,对钛合金TC4高速铣削温度场进行数值仿真。研究切削参数与刀具几何参数对刀具前、后刀面温度及其分布的影响规律。在设定的切削条件下,仿真结果表明:前刀面和后刀面随主轴转速、每齿进给量和径向切深的增加而有不同程度的温升,而轴向切深几乎不对切削温度产生影响;切削温度随刀具直径的增加而增加,但是随着刀具前、后角的增加,切削温度呈先增后减的趋势。     

Experimental investigation on finish intermittent turning of UNS M11917 magnesium alloy under dry machining

An experimental investigation on finish intermittent turning of UNS M11917 magnesium alloy under dry machining is presented. The objective of the study is the analysis of the chip morphology, surface quality and temperature when varying cutting conditions. The intermittent cutting process is analysed using three different workpieces (one continuous and two discontinuous). The experimental plan is based on full factorial designs. Main results of the investigation include the identification of the feed rate as the most important parameter to explain the surface roughness, while no clear influence was found for the cutting speed and slot width. The maximum temperature measured on the tool during the tests was below 50 °C in all of the tests. These low temperature values are explained by the low machining times, depths of cut and cutting speeds used. Thus, for the range of the cutting parameters tested, finish operations can be performed using dry machining under safe conditions. In addition, it was identified that the increase of the depth of cut and feed rate led to higher maximum temperatures, while the increase of the slot width led to lower values. Finally, the morphology of the chips can be classified as segmented chips, including the arc, elemental and spiral chips. Thus, in terms of machining, these chips can be considered as favourable, but, in terms of ignition, these chips are more likely to ignite.