可调节安装角的弹簧刀排

在车削丝杠或蜗杆时,需要选用合适的刀具侧隙角来解决车削螺纹和蜗杆的干涉现象。例如,导程为20mm,中径为50mm丝杠的螺旋升角为7°15′;模数为6mm,中径为50mm的蜗杆螺旋升角为6°15′,则刀的侧隙角应大于10°。所以,加工不同规格的丝杠和蜗杆时应备有各种相应的刀具,而且侧隙角过大还会影响刀具的寿命,降低刀具的强度。     

基于双刀对称车削工艺的杆件加工变形量控制研究

为解决LF6铝合金杆件车削变形量大的问题,提出双刀对称车削工艺,并对杆件进行受力分析,锁定加工参数和加工刀具几何形状作为控制杆件变形的突破口。基于空间填充法对8个变量进行试验设计,通过对试验结果进行机理分析和极差分析,确定切削速度、进给量和刀具前角是控制杆件变形的主要因素,利用单因素试验法得出最优刀具前角为26°。基于中心复合法对切削速度和进给量进行试验设计,通过响应面法建模和哈里斯鹰群算法优化计算,得出最优切削速度为104m/min,最优进给量为0.28mm/r,并对优化结果进行实际加工验证。结果表明：采用双刀对称车削工艺并选取最优参数可有效实现杆件变形量的精准控制,满足实际工程要求。     

7075铝合金切削有限元分析

基于金属切削机理,通过有限元软件建立了二维车削加工有限元仿真模型.经分析可知,在切削速度一定时,随着刀具前角增大,切削力逐渐降低,但刀具前角增大会导致强度降低,最终取前角为10°.在最佳切削刀具前角时,切削速度在一定范围内增加,切削力逐渐降低.经有限元分析得出,切削7075铝合金时选取的最佳切削速度为3000 mm/s...     

金刚石刀具几何参数对已加工表面残余应力的影响

针对微米级切削深度的超精密车削中金刚石刀具几何参数对已加工表面残余应力的影响,采用有限元的方法,建立超精密车削的有限元仿真模型,对硬铝合金的超精密车削过程进行模拟。对车削过程的切削力和切削温度进行分析。采用不同的刀具几何参数进行有限元仿真,得到刀具前角、后角和钝圆半径对已加工表面残余应力的影响和分布规律,为超精密车削中残余应力的控制提供仿真依据。     

采用试验设计法优化铝合金超精密车削加工参数

采用试验设计法对5083铝合金超精密车削的加工参数进行研究和优化,通过部分析因设计和响应曲面方法确认显著影响铝合金超精密车削的加工参数,应用JMP数据统计分析软件对试验结果进行回归分析。试验结果表明,在使用天然金刚石刀具的条件下,影响5083铝合金超精密车削的主要加工参数是进给量和切削速度。当进给量为0.06 mm/r、切削速度为1 010 m/min时,超精密车削加工得到的铝合金表面粗糙度Ra仅为0.03μm,刀具的有效加工距离为34 km,使用寿命明显提升。     

基于AdvantEdge的6061铝合金高速铣削刀具结构参数优化研究

高速铣削过程中,刀具结构参数对刀具的切削性能有非常重要的影响。本文利用专用切削加工有限元分析软件AdvantEdge对6061铝合金高速铣削刀具进行了有限元分析。采用等效二维有限元仿真方法,结合单因素寻优设计方法,分析了硬质合金和高速钢刀具主要的宏、微观参数(包括刀具刃口钝圆半径、前角和后角等)对铣削加工过程中的温度、应变、切削力等参数的影响趋势。仿真结果显示,为获得较好的切削效果,铣刀取较小的刃口钝圆半径(即0.04mm左右);可取较大的前角和后角,前角为12°-15°,后角为15°-20°。     

基于Inconel 718车削过程有限元仿真的刀具刃口几何参数优化

基于Third Wave Advant Edge建立二维有限元模型,对镍基高温合金Inconel 718的车削过程进行数值仿真分析,并通过直角车削试验验证仿真模型的精准度;提出了刃口几何参数的优化流程,获得了不同刃口几何参数下的切削温度和应力分布,研究了刀具刃口几何参数对刀具应力及刀具温度的影响,进而对加工镍基合金的刀具刃口参数进行优化。仿真结果表明:在选定后角7°时,粗加工镍基合金Inconel 718的最优前角为6°,最优刃口钝圆半径为60μm;随着刀具前角的增加(0°~10°),切削温度逐渐增加,刀具应力先减小后增加,切屑的高温区逐渐减小,刀具的高应力区逐渐向后刀面扩展;随着刃口钝圆半径的增加(30μm~80μm),刀具温度逐渐增加,温度分布无明显变化,刀具应力先减小后增加,切削刃附近应力集中现象减弱。     

基于热—力耦合理论的刀具结构设计

本文提出一种基于热—力耦合理论的刀具结构设计方法,基于DEFROM 2D/3D软件设计通过硬质合金平头倒角立铣刀,并进行高速铣削7075合金钢的仿真实验,在主轴转速为4000r/min、进给速度为2000mm/min、切削深度为0.1mm的参数下,对影响切削力和切削热的主要刀具结构参数(前角、后角、螺旋角及刀具刃数)进行了仿真研究。研究表明,在此工艺环境下,当结构参数为前角15°、后角10°、螺旋角35°及四刃的刀具齿数时,设计刀具相较于普通刀具的最大切削力下降4.1%,平均切削力下降5%,切削热下降7.4%。     

PCD刀具几何参数对铝合金切削力的影响

研究了不同几何参数的PCD刀具车削铝合金时切削力的变化规律。分别改变刀具的前角、后角和刀尖圆弧半径三个几何参数进行单因素切削试验,通过Kistler测力仪获取三向切削力,通过所获试验数据分析了金属切削过程和PCD刀具几何参数对切削力的影响。     

基于H62黄铜的大直径菲涅尔透镜模具加工工艺实验研究

以振动法和声发射技术为基础,采用超精密金刚石车削加工技术对H62黄铜模具材料进行大直径菲涅尔透镜模具加工工艺的实验研究。实验表明:刀尖角、刀具后角和切削液是影响加工表面质量的主要因素。当刀尖角54°、刀具后角3°、切削液采用微乳化液时,切削状态最佳,可以有效地提高刀具耐用度和加工表面质量。     

Finite element simulation and experimental investigation of tool temperature during ultrasonically assisted turning of aerospace aluminum using multicoated carbide inserts

This paper summarizes the results of thermal finite element simulation and experimental studies of tool temperature in ultrasonic-assisted turning (UAT) of aerospace aluminum using multicoated carbide inserts. At first, mathematical models were developed in order to study the effects of tool coating, rake angle, cutting speed, and feed rate on the friction coefficient. Then with respect to the kinematics of the process, the cutting velocity model would be presented. This velocity model is used in combination with the mathematical model to define the friction coefficient during UAT. The mentioned frictional model is used to write a user subroutine to incorporate the effect of friction coefficient as a function of cutting parameters in the finite element program Abaqus. The results of this simulation make it possible to determine cutting temperature patterns accurately. It is also used to study the effect of cutting parameters (cutting speed, feed rate, rake angle, and vibration amplitude) on UAT. Finally, the simulation results are compared with experimental measurements of cutting temperatures from ultrasonic-assisted turning tests. The results show that ultrasonic-assisted turning is able to lower the maximum cutting temperature in cutting tool, about 29 %, in low feed rates (≈0.14 mm/rev), with a vibration amplitude of ≈10 μm and work velocity of ≈0.5 m/s.     

FUZZY CLUSTERING MODELLING FOR SURFACE FINISH PREDICTION IN FINE TURNING PROCESS

ABSTRACT

In this paper, fuzzy subtractive clustering based system identification and Sugeno type fuzzy inference system are used to model the surface finish of the machined surfaces in fine turning process to develop a better understanding of the effect of process parameters on surface quality. Such an understanding can provide insight into the problems of controlling the quality of the machined surface when the process parameters are adjusted to obtain certain characteristics. Surface finish data were generated for aluminum alloy 390 (73 BHN), ductile cast iron (186 BHN), and inconel 718 (BHN 335) for a wide range of machining conditions defined by cutting speed, cutting feed rate and cutting tool nose radius. These data were used to develop a surface finish prediction fuzzy clustering model as a function of hardness of the machined material, cutting speed, cutting feed rate, and cutting tool nose radius. Surface finish of the machined part is the output of the process. The model building process is carried out by using fuzzy subtracting clustering based system identification in both input and output space. Minimum error is obtained through numerous searches of clustering parameters. The fuzzy logic model is capable of predicting the surface finish for a given set of inputs (workpiece hardness, cutting speed, cutting feed rate and nose radius of the cutting tool). As such, the machinist may predict the quality of the surface for a given set of working parameters and may also set the process parameters to achieve a certain surface finish. The model is verified experimentally by further experimentation using different sets of inputs. This study deals with the experimental results obtained during fine turning operation. The findings indicate that while the effects of cutting feed and tool nose radius on surface finish were generally consistent for all materials, the effect of cutting speed was not. The surface finish improved for aluminum alloy and ductile cast iron but it deteriorated with speed for inconel.     

FUZZY CLUSTERING MODELLING FOR SURFACE FINISH PREDICTION IN FINE TURNING PROCESS

In this paper, fuzzy subtractive clustering based system identification and Sugeno type fuzzy inference system are used to model the surface finish of the machined surfaces in fine turning process to develop a better understanding of the effect of process parameters on surface quality. Such an understanding can provide insight into the problems of controlling the quality of the machined surface when the process parameters are adjusted to obtain certain characteristics. Surface finish data were generated for aluminum alloy 390 (73 BHN), ductile cast iron (186 BHN), and inconel 718 (BHN 335) for a wide range of machining conditions defined by cutting speed, cutting feed rate and cutting tool nose radius. These data were used to develop a surface finish prediction fuzzy clustering model as a function of hardness of the machined material, cutting speed, cutting feed rate, and cutting tool nose radius. Surface finish of the machined part is the output of the process. The model building process is carried out by using fuzzy subtracting clustering based system identification in both input and output space. Minimum error is obtained through numerous searches of clustering parameters. The fuzzy logic model is capable of predicting the surface finish for a given set of inputs (workpiece hardness, cutting speed, cutting feed rate and nose radius of the cutting tool). As such, the machinist may predict the quality of the surface for a given set of working parameters and may also set the process parameters to achieve a certain surface finish. The model is verified experimentally by further experimentation using different sets of inputs. This study deals with the experimental results obtained during fine turning operation. The findings indicate that while the effects of cutting feed and tool nose radius on surface finish were generally consistent for all materials, the effect of cutting speed was not. The surface finish improved for aluminum alloy and ductile cast iron but it deteriorated with speed for inconel.     

Machinability issues in turning of Al-SiC (10p) metal matrix composites

The paper presents the results of an experimental investigation on the machinability of fabricated aluminum metal matrix composite (A356/SiC/10p) during continuous turning of composite rods using medium grade polycrystalline diamond (PCD 1500) inserts. MMC’s are very difficult to machine and PCD tools are considered by far, the best choice for the machining of these materials. Experiments were conducted at LMW-CNC-LAL-2 production lathe using PCD 1500 grade insert at various cutting conditions and parameters such as surface roughness, specific power consumed, and tool wear were measured. Machining was continued till the flank wear land on the tool crossed 0.4 mm. The influences of cutting speed on the insert wear and built-up edges (BUEs) formation were studied. The present results reaffirm the suitability of PCD for machining MMCs. Though BUE formation was observed at low cutting speeds, at high cutting speeds very good surface finish and low specific power consumption could be achieved.     

Development of a programmable vibration cutting tool for diamond turning of hardened mold steels

There are two drawbacks in the performance of the resonant vibration cutting tools currently available. One is that the vibration frequency cannot be changed arbitrarily and the other is that the cutting force is low. It is impossible to turn mirror plates with many kinds of materials using these resonant vibration cutting tools because they cannot match the desirable turning speeds that correspond to the machined materials and the vibration frequency needs to be increased or decreased to obtain the desired surface roughness. Resonant vibration cutting tools do not allow the vibration frequency to be set arbitrarily. The small cutting force of these tools also causes some difficulties in diamond turning of metals other than soft metals such as aluminum and copper. In this research, we developed a vibration cutting tool that can generate two-dimensional vibration shapes without distortion by placing two piezoelectric actuators at right angles. This tool can machine the many kinds of mirror plates with different materials to the desired surface roughness. It is also possible to machine hard materials such as mold steels because the amplitudes of the vibrations do not decrease, even when large cutting forces are required. In this paper, we describe the design of the nonresonant vibration cutting tool, and show by the diamond turning of oxygen-free copper and aluminum that our nonresonant vibration cutting tool can machine desired shapes. Finally, it is verified by actual machining experiments that the proposed vibration cutting tool can machine hardened mold steels such as STAVAX with HRC 54.     

碳化硅增强颗粒含量和尺寸对铝基复合材料超精密车削表面的影响

用聚晶金刚石刀具(PCD)研究了增强颗粒的含量、尺寸等对SiC颗粒增强铝基复合材料超精密车削表面的影响.结果表明:SiC增强颗粒的去除方式主要有拔出、破碎和切断等,SiC颗粒的含量和平均尺寸越大,其拔出和破碎现象就越多,复合材料获得的加工表面粗糙度值也越大;当SiC颗粒主要以切断方式被去除时,可望获得含有较少坑洞和裂纹等加工缺陷的超精密切削表面.     

A MACHINING PERFORMANCE STUDY IN DRY CONTOUR TURNING OF ALUMINUM ALLOYS WITH FLAT-FACED AND GROOVED DIAMOND TOOLS

This paper presents the results from an experimental study of dry contour turning operations on aluminum alloys (6061B and 2011-T3) using PCD flat-faced and diamond coated grooved tools. The machining performance is assessed on the basis of cutting forces, chip flow, chip-form and surface roughness observed during contour turning operations. The constantly varying cutting conditions (especially effective depth of cut due to varying geometry of the contour surface) and effective tool geometry cause a wide fluctuation in cutting forces and the ensuing chip flow. The chip flow angle is measured along the contour geometry using high-speed filming techniques and these results are compared with predicted chip flow values from the measured experimental cutting forces (which are measured along the entire contour geometry). The resultant surface roughness at different locations along the contour profile is measured and correlated with the chip flow and chip-form variations. Machining performance issues specifically relevant to dry contour turning of aluminum (such as problems due to poor chip flow and the resultant poor surface roughness) are studied and the effectiveness of selective work-tool (both tool material and tool geometry) pairs is illustrated.     

金刚石厚膜刀具切削性能的研究

制备了机夹式金刚石厚膜刀具 ,通过切削试验研究了金刚石厚膜刀具精密车削LY12铝合金时切削用量 (进给速度vf、切削速度v和切削深度ap)对切削表面粗糙度的影响     

PCD刀具车削超硬铝合金的切削性能研究

以Al7075-T6为加工对象,通过车削试验对PCD刀具车削超硬铝合金的三向动态切削力和表面粗糙度展开研究,建立基于BP神经网络的切削力和表面粗糙度预测模型。结果表明:随着切削用量三要素的变化,切削力变化显著;对于表面粗糙度而言,背吃刀量、进给量和切削速度之间无交互作用;基于L-M优化算法的BP神经网络对样本的拟合度高,且对切削力和表面粗糙度的预测精度高。     

Performance improvement of hard turning with solid lubricants

Product quality is one of the most important criteria for the assessment of hard turning process. However, in view of the high temperatures developed in hard turning process, the surface quality deteriorates due to the tool wear. Because of the strict environmental restrictions on the use of cutting fluids, new cutting techniques are required to be investigated to reduce the tool wear. In the present work, the use of solid lubricants during hard turning has been explored while machining bearing steel with mixed ceramic inserts at different cutting conditions and tool geometry. Results show considerable improvement in the surface finish with the use of solid lubricants. Due to the presence of solid lubricants, there is a decrease of surface roughness values from 8 to 15% as compared to dry hard turning.