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预应力切削镍基高温合金的试验研究 总被引:5,自引:0,他引:5
针对镍基高温合金在切削后加工表面分布严重的残余拉应力等问题,提出采用预应力切削方法,以实现在加工过程中主动控制加工表面残余应力分布状态;通过研制轴类零件的车床专用预拉伸装置,在0 MPa、150 MPa和300 MPa三种预应力条件下对高温合金轴件进行预拉伸处理;通过硬质合金刀具预应力切削镍基高温合金的对比试验,对三种预应力条件下的切削力、切屑形态以及表面完整性包括已加工表面残余应力、加工表面粗糙度、表面形貌和显微硬度等指标进行对比。结果表明:在一定范围内,采用预应力切削方法可省去加工后续的残余应力调整工序,并能在加工表面获得合适的残余压应力;残余压应力的值可通过调整施加的预应力大小来进行主动控制;与普通切削相比,预应力切削可得到均匀的锯齿形切屑,切削力没有显著增加;预应力切削可获得良好的表面完整性,且不会引来额外的加工硬化。 相似文献
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为研究预应力条件对镍基高温合金切削加工的影响,采用Abaqus/Explicit软件建立了预应力切削镍基高温合金的三维有限元模型,研究了不同预应力状态下的切削力和加工表面各向应力的分布规律,分析了预应力条件对切屑形状、切削力和表面残余应力的影响,并与实验结果进行对比。研究结果表明:预应力作用对切削力和切屑形状的影响不显著;预应力作用对与预应力加载方向相同的已加工表面应力影响最大,并随着预应力的增大此方向上应力的分布层深显著增大,而对其他方向上的应力分布影响不显著;在一定范围内,随着预应力的增大已加工表面残余压应力值大小和分布层深都显著增大。 相似文献
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钛合金Ti-6Al-4V高压冷却车削过程有限元分析 总被引:1,自引:0,他引:1
随着钛合金的广泛应用,改善其切削加工性、提高加工表面完整性的试验研究也已得到广泛重视,但对该过程的仿真分析尚不成熟。通过Deform 3D仿真软件建立有限元仿真模型,模拟钛合金Ti-6Al-4V在干切削、普通冷却及高压冷却环境下的车削过程,研究切削环境对切削力、切削温度等加工过程量的影响,获取已加工工件距离加工表面不同深度的残余应力分布,分析高压冷却对钛合金Ti-6Al-4V加工表面残余应力的影响规律。通过钛合金Ti-6Al-4V车削试验测量切削力及刀具表面切削温度,并与有限元仿真模型对比,以验证其可靠性。仿真结果表明:随着切削液压强的增加,切削力增加,刀具表面切削温度降低,高压冷却可有效增强切削液的冷却作用。干切削时,已加工表面(d2=0)为残余拉应力;随着切削液压强的增加,已加工表面残余应力状态逐渐由残余拉应力向残余压应力转变,当切削液压强为200 bar时,已加工表面残余应力为残余压应力,且此时已加工表面残余压应力为最大值。随着测量深度的增加,残余应力值增大,在所有切削试验中,最大残余压应力值均在距离已加工表面相同距离。仿真结果与试验结果的对比证明了有限元仿真模型的可靠性,为钛合金Ti-6Al-4V高压冷却加工热力耦合分析和优化设计提供了理论依据。 相似文献
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数控车削刀具圆弧半径对切削过程影响的数值分析 总被引:2,自引:0,他引:2
数控车削加工中刀具的圆弧半径对切削力,切屑的断屑,切屑的形状,加工表面质量、加工变形以及已切削表面的残余应力的大小,状态,分布有着很大的影响.本文采用有限元分析方法,利用有限元增量理论,建立了二维金属切削仿真模型,分析中采用网格自适应准则,模拟了典型零件车削二维切削过程中切屑的形成,得到了加工后已加工表面的残余应力的大小,状态以及分布状况,对于工程中的实际应用具有重要的意义. 相似文献
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切削用量对钛合金已加工表面残余应力的影响 总被引:1,自引:0,他引:1
《工具技术》2013,(10):33-37
为了得到切削用量对钛合金加工表面残余应力的影响,本文根据金属切削有限元分析相关理论,建立了三维斜角切削有限元模型,对钛合金Ti6Al4V的铣削加工进行了模拟分析,得到了切削速度和切削深度对工件加工表面残余应力的影响。由模拟结果得出:残余应力随切削速度的增大而逐渐增加,切削速度对加工表面残余应力的影响较大,同时随着切削速度的改变,表面残余应力层的厚度有上升趋势;残余应力在已加工表面外表面表现为拉应力,沿深度方向由拉应力逐渐过渡到压应力;切削深度对残余应力及残余应力层的影响都较小。 相似文献
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基于Doelle—Hauk方法测量了铣削加工铝合金工件表面的残余应力状态,结果表明,应力主平面与试样表面基本平行,说明铣削加工铝合金表面的残余应力近似处于二维平面应力状态。在分析了织构对残余应力测试影响的基础上,采用X射线衍射法中的回摆法测量了铣削加工工件表面不同切削几何位置、不同转速下残余应力的分布规律。为了对残余应力的分布作出解释,采用Kisterler测试仪测试了不同主轴转速下切削力的变化规律;建立了双刃斜角切削有限元模型,得到了单个切屑形成时已加工工件表面的切削温度场。最后,从热力耦合的角度对残余应力的形成机理进行了研究。 相似文献
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Qin Meng-yang Ye Bang-yan Jia Xiong He Ai-dong 《The International Journal of Advanced Manufacturing Technology》2013,65(1-4):355-361
This paper presents an analysis and experimental study on the formation and distribution of machined surface residual stress in pre-stress cutting. In the first component of the paper, the mechanical and thermal effect on residual stress is analysed. The results show that machined harden layer and cutting heat transfer conditions are crucial to form residual stress in a machined surface. Residual stress has three kinds of distributions in different mechanical and thermal conditions: tensile stress, compressive stress and tensile–compressive stress. If pre-stress is applied, it would facilitate residual compressive stress in the machined surface effectively; its action is analysed with an experimental study. The experiment is carried out by hardened 40Cr alloy steel turning with different tool rounds and pre-stress loading; the results obtained in this study indicate that the tool round would redound to generate residual compressive stress in the machined surface and affect the residual stress distribution significantly, whilst pre-stress load can affect the magnitude of residual stress actively, but does not for its distribution. It is found that the experimental results of residual stress distribution are consistent with the theoretical analysis. 相似文献
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钛合金关节轴承是航空发动机的重要部件之一,但由于其润滑条件较差,极易产生磨损从而导致失效事故。采用超声滚压工艺对钛合金试件表面进行强化试验,以有效增强试件表面耐磨性能和抗疲劳特性,并着重研究静压力、滚压次数和主轴转速等超声滚压强化工艺参数对钛合金表面残余压应力与剪切应力的影响规律。试验结果与理论分析结果表明,残余压应力随着静压力、滚压次数和主轴转速的提高而增大,剪切应力随着静压力、滚压次数和主轴转速的提高而总体减小;滚压后试件表面可获得-2 000~-500 MPa的残余压应力和-600~-300 MPa的剪切应力。超声滚压技术可以有效提高钛合金材料表面的残余压应力,并有效降低表面的剪切应力。 相似文献
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Disc milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on the difficult-to-cut material. The processing efficiency of machined components thus can be tremendously improved with the application of disc milling. However, the fundamental research of the mechanisms of disc milling on cutting metal materials, especially on titanium alloys, is lacking in the literature. In this study, the milling force and temperature were inspected in disc milling grooving experiment, and the effect of thermal-mechanical coupling on surface integrity of titanium alloy, including surface roughness, surface topography, surface and subsurface residual stress, microstructure, and microhardness, was analyzed. The results showed that a better surface quality can be obtained at the center of the surfaces compared to the marginal regions on the same machined surface. Residual compressive stress was generated on the machined surface and subsurface and gradually reduced to zero with an increase in depth. The microstructure of lattice tensile deformation was emerged along feed direction, while the phase transition was not produced. A hardened layer was found on the machined surface and subsurface, mostly causing by the mechanical loads and oxidation reaction. 相似文献
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A thermo-elastic–viscoplastic model using explicit finite element code Abaqus was developed to investigate the effect of sequential cuts and tool–chip friction on residual stresses in a machined layer. Chip formation, cutting forces and temperature were also examined in the sequential cuts. The affected layer from the first cut slightly changes the chip thickness, cutting forces, residual strain and temperature of the machined layer, but significantly affects the residual stress distribution produced by the second cut. Residual stress is sensitive to friction condition of the tool–chip interface. Simulation results offer an insight into residual stresses induced in sequential cuts. Based on simulation results, characteristics of residual stress distribution can be controlled by optimizing the second cut. 相似文献
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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. 相似文献