可转位车刀切削过程三维有限元集成仿真

利用三维有限元方法对金属的切削加工过程进行了模拟仿真。按照实际加工条件建立了切削模拟模型,模拟中按照国家标准建立的硬质合金可转位刀片的三维模型不仅考虑了真实的刀片几何形状,而且考虑了刀片安装时的角度参数。利用成熟的商业软件DEFORM3D对金属切削过程中切屑的流动状态及过程中的温度场和应力场进行了有限元模拟并对模拟结果进行了分析。     

斜角切削过程的三维热—弹塑性有限元分析

基于大变形理论和虚功原理,建立了斜角切削加工过程的三维热一弹塑性有限元模型.分析和研究了涉及切削加工有限元模拟的关键技术.采用通用有限元求解器ABAQUS/Explicit对斜角切削过程进行了有限元模拟,分析了切削过程中切屑的形成过程及其形貌、三维切削力的变化情况,以及应力、应变、切削温度和已加工表面残余应力的分布规律.通过与试验数据的比较,证明了所建立有限元模型的正确性.斜角切削过程的三维热一弹塑性有限元模拟研究为铝合金高速切削加工的工艺参数优化、刀具几何参数的合理选择提供了参考.     

高速硬态切削参数影响的有限元分析

研究了切屑分离、刀屑摩擦等关键技术,建立了轴承钢GCrl5高速切削的有限元模型.根据实际切削加工状况选择适当的切削参数,建立了正交试验表,利用有限元软件进行了有限元模拟,研究了刀具负前角和切削参数对切削力、温度、应力应变等的影响程度和趋势.该有限元模型可以用于分析切削参数对切削过程的影响,为下一步参数优化研究奠定了基础.     

PCBN刀具磨损对切削过程影响的有限元仿真研究

在实际切削加工中,随着切削的进行,刀具的磨损会越来越严重,这种磨损会严重影响切削过程,对切削力、切削温度等影响极大。本文通过有限元仿真软件ABAQUS模拟了不同磨损程度的PCBN刀具切削高强度钢Cr12Mo V的过程,揭示出了刀具磨损量对切削过程的影响规律,并通过试验进行了验证。     

基于热力耦合模型的切削加工残余应力的模拟及试验研究

航空精密薄壁零件具有复杂的型腔结构,切削加工残余应力是薄壁零件精度稳定性的重要影响因素,因此必须对切削加工残余应力进行研究。根据热—弹塑性有限元理论,建立切削加工三维有限元模型,对航空铝合金材料Al2A12进行切削加工非线性弹塑性有限元模拟分析,对切削加工表面残余应力进行预测和计算。通过有限元分析,得到不同切削参数、刀具参数条件下的已加工表面残余应力的模拟结果,并对结果进行比较分析,得到各个因素对工件已加工表面残余应力的基本影响规律;进行不同加工工序条件下的切削加工残余应力的有限元模拟,在加工表面已有一次切削加工残余应力分布的情况下,进行二次切削加工有限元模拟,得到二次切削加工对工件已加工表面残余应力的影响规律;并且进行不同切削参数对残余应力影响的试验研究,验证有限元模型的正确性。     

基于有限元法的二维正交切削刀具应力分析

运用有限元方法对二维正交切削加工刀具内部应力进行模拟分析。基于刚塑性有限元方法建立了切削加工过程仿真模型,通过模拟获得了切削加工过程中刀具应力的分布和变化情况。通过对不同切削工艺参数条件下的切削过程进行模拟,分析了刀具几何参数以及切削用量对切削加工过程中刀具应力的影响,为正确选择刀具及切削参数提供了参考。     

薄壁件立铣切削力的有限元模拟与实验研究

薄壁件铣削加工中铣削力是导致加工变形的直接原因,是加工误差的主要影响因素.在考虑刀具变形、工件及刀具材料性能参数的基础上,建立了三维斜角切削力有限元模型,利用有限元分析软件ABAQUS对薄壁件斜角切削过程进行了仿真模拟.其次,针对铣削过程进行了切削力测试,结果表明本文提出的切削力有限元模拟方法具有较高的精度,对切削参数的优化提供了理论依据和便利工具.     

镍基高温合金切削过程有限元仿真及刀具参数研究

为了准确模拟高温合金GH4169的切削过程,深入研究了GH4169的有限元建模技术,如有限元模型的建立、材料本构模型、切屑分离准则及接触摩擦模型等。采用Johnson-Cook本构关系模型对GH4169的加工过程进行二维正交切削有限元模拟,获得了不同刀具前角下的切屑形态和切削力曲线图,进一步分析了刀具前角对切屑形态和切削力变化规律的影响,为镍基高温合金的实际切削加工中刀具的选择提供了参考。     

基于变形有限元仿真的薄壁套筒加工参数优选

为了实现薄壁件加工中的最小形变,利用UG NX软件的有限元仿真模块,对薄壁件车削加工参数优选进行了研究。通过建立有限元仿真模型,分析某一加工瞬时薄壁件受力变形情况,并通过切削实验对比仿真结果,实验结果表明:仿真模拟数据与实际测量数据具有较高一致性。最后设计了基于有限元仿真模拟的正交实验,优选最佳切削参数组合。     

模具淬硬钢高速铣削加工的有限元模拟

研究了高速铣削加工数值模拟所涉及的切削层等效简化铣削加工模型,分析了工件材料的流动应力模型与刀屑接触面的摩擦模型和热传导控制方程等关键技术.并根据等效简化模型平面应变特征的特点,建立了铣削加工数值模拟的2-D有限元模型.基于此模型对高速铣削加工淬硬钢P20的切削力、应力和温度进行了有限元模拟.通过铣削力切削加工实验测得了相同条件下的铣削力值.结果表明:实验铣削力值与数值模拟在一定的误差范围内结果一致.由此可见,采用具有平面应变特征的有限元模型进行应力和温度的模拟切削过程是可信的.高速铣削加工有限元模拟研究为淬硬钢切削加工的工艺参数优化、刀具的优选和工艺规划奠定了基础.     

锯齿形切屑的计算机仿真

采用有限元方法仿真了不同切削速度下加工45钢的切屑形成过程。结果表明，较低切削速度下形成连续带状切屑，而高速切削时形成锯齿形切屑。通过对工件和切屑应力及温度分布的分析，探讨了锯齿形切屑的形成机理及影响因素。     

Adiabatic Shear Mechanisms for the Hard Cutting Process

The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimen...     

NANOSCALE CUTTING OF MONOCRYSTALLINE SILICON USING MOLECULAR DYNAMICS SIMULATION

It has been found that the brittle material, monocrystalline silicon, can be machined in ductile mode in nanoscale cutting when the tool cutting edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to better understand the mechanism of ductile mode cutting of silicon, the molecular dynamics (MD) method is employed to simulate the nanoscale cutting of monocrystalline silicon. The simulated variation of the cutting forces with the tool cutting edge radius is compared with the cutting force results from experimental cutting tests and they show a good agreement. The results also indicate that there is silicon phase transformation from monocrystalline to amorphous in the chip formation zone that can be used to explain the cause of ductile mode cutting. Moreover, from the simulated stress results, the two necessary conditions of ductile mode cutting, the tool cutting edge radius are reduced to nanoscale and the undeformed chip thickness should be smaller than the tool cutting edge radius, have been explained.     

内冷式高压冷却车刀切削性能的研究

研究中对关于切削温度和切屑折断方面新型内冷式高压冷却车刀的切削性能进行了仿真和实验分析。研究结果表明,在切削过程中喷射的高压冷却液可以最大限度地带走刀-屑-工件系统中的热量,使冷却更高效,还可以通过改变润滑摩擦条件和剪切角度(剪切性能)来改善切削状况,迫使切屑卷曲折断并强烈控制切屑的形成。最终在高压射流的热效应和机械效应的综合作用下,改善切削温度的同时得到较小弯曲半径的碎屑,从而增强了切削过程中的工艺稳定性和加工安全性。     

航空铝合金7075-T7451三维铣削过程有限元仿真

采用有限元分析软件AdvantEdge建立反映金属切削过程高温、大应变及高应变率状态的切削模型,模拟了航空铝合金7075-T7451铣削加工过程,获得了两个铣削周期内的铣削力变化曲线,并预测了工件及刀具上的温度分布;模拟了铣削过程中切屑的形成,获得了与实际切屑相似的切屑形状。通过铣削力实验获得了相同铣削条件下的铣削力值,与模拟铣削力值比较,发现两者具有较好的一致性,从而证明了有限元模型的正确性。     

45钢高速切削过程中切屑形成的数值模拟

为了研究45钢高速加工中切屑形成机理,建立了高速加工的正交切削有限元模型,研究了45钢高速切削有限元建模过程中的Johnson-Cooks材料模型,刀屑接触模型及切屑分离准则等关键技术.利用建立的有限元模型对45钢的高速切削过程中的切屑成形进行了数值模拟,并研究了不同切削速度对切屑锯齿化程度的影响规律,得到了不同切削速度下的切屑锯齿化程度.     

2D FEM estimate of tool wear in turning operation

Finite element method (FEM) is a powerful tool to predict cutting process variables, which are difficult to obtain with experimental methods. In this paper, modelling techniques on continuous chip formation by using the commercial FEM code ABAQUS are discussed. A combination of three chip formation analysis steps including initial chip formation, chip growth and steady-state chip formation, is used to simulate the continuous chip formation process. Steady chip shape, cutting force, and heat flux at tool/chip and tool/work interface are obtained. Further, after introducing a heat transfer analysis, temperature distribution in the cutting insert at steady state is obtained. In this way, cutting process variables e.g. contact pressure (normal stress) at tool/chip and tool/work interface, relative sliding velocity and cutting temperature distribution at steady state are predicted. Many researches show that tool wear rate is dependent on these cutting process variables and their relationship is described by some wear rate models. Through implementing a Python-based tool wear estimate program, which launches chip formation analysis, reads predicted cutting process variables, calculates tool wear based on wear rate model and then updates tool geometry, tool wear progress in turning operation is estimated. In addition, the predicted crater wear and flank wear are verified with experimental results.     

NUMERICAL SIMULATION OF TITANIUM ALLOY DRY MACHINING WITH A STRAIN SOFTENING CONSTITUTIVE LAW

In this study, the commercial finite element software FORGE2005®, able to solve complex thermo-mechanical problems is used to model titanium alloy dry machining. One of the main machining characteristics of titanium alloys is to produce a special chip morphology named “saw-tooth chip” or serrated chip for a wide range of cutting speeds and feeds. The mechanism of saw-tooth chip formation is still not completely understood. Among the two theories about its formation, this study assumes that chip segmentation is only induced by adiabatic shear band formation and thus no material failure occurs in the primary shear zone. Based on the assumption of material strain softening, a new material law was developed. The aim of this study is to analyze the newly developed model's capacity to correctly simulate the machining process. The model validation is based on the comparison of experimental and simulated results, such as chip formation, global chip morphology, cutting forces and geometrical chip characteristics. A good correlation was found between the experimental and numerical results, especially for cutting speeds generating low tool wear.     

高速切削锯齿状切屑的有限元模拟

采用合理的断裂准则对高速硬切削条件下锯齿状切屑的形成进行了有限元模拟 ,并分析了切削过程中的应力场、应变场及温度场 ,探讨了锯齿状切屑的形成机理及影响因素。     

Finite element simulation for burr formation near the exit of orthogonal cutting

A coupled thermo-mechanical model of plane-strain orthogonal metal cutting including burr formation is presented using the commercial finite element code. A simulation procedure based on Normalized Cockroft–Latham damage criterion is proposed for the purpose of better understanding the burr formation mechanism and obtaining a quantitative analysis of burrs near the exit of orthogonal cutting. The cutting process is simulated from the transient initial chip formation state to the steady state of cutting, and then to tool exit transient chip flow by incrementally advancing the cutting tool. The predicted burr profile is compared with experimental data and found to be in reasonable agreement. The effect of the tool conditions and cutting conditions on the burr formation process was also investigated.