共查询到19条相似文献,搜索用时 453 毫秒
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切削SiCp/Al复合材料刀尖圆弧半径对棱边缺陷的影响 总被引:2,自引:0,他引:2
运用有限元软件ABAQUS建立了二维切削有限元模型,模拟了碳化硅颗粒增强铝基(SiCp/Al)复合材料的切削过程。通过切削过程中等效应力的变化分析了棱边缺陷的形成过程,进而研究刀尖圆弧半径对切削时出口棱边缺陷的影响。结果表明,在其他切削条件相同的情况下,棱边缺陷随刀尖圆弧半径的增加而逐渐增大。 相似文献
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《机械科学与技术》2016,(6):896-900
在不同的切削条件下工件的棱边会形成毛刺与亏缺两种不同的形态。亏缺的形成同样影响着工件的精度与使用性能。基于Normalized CockroftLatham断裂准则建立了毛刺与亏缺形成的有限元热-力耦合模型,通过模拟结果分析,得出毛刺的形成主要由工件终端部材料的大塑性变形而产生,亏缺的形成主要由工件已加工面材料的大塑性变形造成的韧性断裂产生。并通过不同的切削条件模拟,得出了形成亏缺的界限条件。切削实验结果表明:模拟结果中的界限条件与实验结果接近。毛刺、亏缺形成有限元模型的建立为进一步深入研究其形成机理提供了一条有效的途径,其模拟结果为工件棱边质量的控制提供参考。 相似文献
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为研究径向超声振动参数及切削参数对车削6061铝合金表面残余应力、表面粗糙度以及表面形貌的影响,采用与普通车削进行对比的方法对6061铝合金进行纵向超声振动切削试验。结果表明:与普通车削相比,径向超声振动辅助车削能显著提高零件加工表面的残余压应力;在两种切削方式下,表面残余压应力均随切削速度的增加而增大;在相同切削参数下,随着径向超声振幅的增加,6061铝合金加工表面的残余压应力变大;与普通车削相比,径向超声振动车削使工件表面的粗糙度变大,并且伴随振幅的增加,表面粗糙度呈上升趋势;通过对加工表面的三维形貌进行观测发现,超声振动辅助车削能有效抑制传统车削加工中的积屑瘤和鳞刺等表面缺陷,并显著提高加工表面质量。 相似文献
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CFRP/Al叠层材料各组分的材料力学性能迥异,采用传统的基于单组分材料制孔加工方法极易出现孔口孔径超大、孔口毛刺、孔壁表面损伤等加工缺陷。因此在深孔啄钻加工工艺的基础上,提出一种分层变参数的加工工艺,并与两种啄钻方案进行实验对比研究,从切削断屑效果、制孔质量两个维度分析可得:分层变参数的加工工艺对控制切屑形态和抑制制孔缺陷具有一定优势。 相似文献
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运用有限元软件AdvantEdge对7050铝合金材料进行了切削加工仿真模拟,采用单一变量法得到了工件表面残余应力与切削温度随切削参数改变而发生变化的规律。结果表明:工件表层为残余压应力,亚表层为残余拉应力,切削参数对最大残余应力所在深度影响较小,进给量对工件表面的残余应力影响最大,切削速度次之,背吃刀量最小,切削温度随着切削参数的改变也呈现出一定的规律。 相似文献
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Influence of size effect on burr formation in micro cutting 总被引:3,自引:1,他引:2
Tao Zhang Zhanqiang Liu Chonghai Xu 《The International Journal of Advanced Manufacturing Technology》2013,68(9-12):1911-1917
Burr is an important character of the surface quality for machined parts, and it is even more severe in micro cutting. Due to the uncut chip thickness and the cutting edge radius at the same range in micro cutting process, the tool extrudes the workpiece with negative rake angle. The workpiece flows along the direction of minimum resistance, and Poisson burr is formed. Based on the deformation analysis and experiment observations of micro cutting process, the factor for Poisson burr formation is analyzed. It is demonstrated that the ratio of the uncut chip thickness to the cutting edge radius plays an important role on the height of Poisson burr. Increasing the uncut chip thickness or decreasing the cutting edge radius makes the height of exit burr reduce. A new model of micro exit burr is established in this paper. Due to the size effect of specific cutting energy, the exit burr height increases. The minimum exit burr height will be obtained when the ratio of uncut the chip thickness to the cutting edge radius reaches 1. It is found that the curled radius of the exit burr plays an important role on the burr height. 相似文献
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Li Zhou Ning Hou Shutao Huang Lifu Xu 《The International Journal of Advanced Manufacturing Technology》2014,72(9-12):1407-1414
In this study, orthogonal cutting of SiCp/Al composites with a polycrystal diamond tool has been carried out. The influences of cutting velocity, cutting depth, and tool rake angle on the cutting force and edge defects near the exit of orthogonal cutting were analyzed in detail. The research results show that the influence of the cutting depth on cutting force is most obvious, and there is a close relationship between the cutting force and the size of edge defects. At the same time, the fractographs indicated that the brittle fracture mode corresponds to the dominant failure mode during machining of SiCp/Al composites with higher volume fraction and larger SiC particle. Therefore, in the precision and super-precision manufacturing of SiCp/Al composites, with a proper tool rake angle, adopting higher cutting velocity and lower cutting depth not only can reduce the cutting force effectively but also can ensure cutting edge quality. 相似文献
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Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production. 相似文献
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Y.J. Kim J.H. Kim S.L. Ko B.K. Kim 《The International Journal of Advanced Manufacturing Technology》2006,29(9-10):879-884
The exit burr generated in the face milling operation at the edge of the workpiece usually requires deburring processes to enhance the level of precision of the parts. This paper is to geometrically understand the formation of the exit burr in the face milling operation on the arbitrary shaped workpiece with multiple feature such as hole, spline, and arc so that we can suggest the cutting conditions and tool path to minimize the burr formation on the given workpiece in the early design stage. The burr formation mechanism in each type of burr is classified based on the experimental results. A database is developed to store and predict burr formation results. A Windows based program is developed with the algorithm including three steps, i.e., the feature identification, the cutting condition identification, and the analysis on exit burr formation. We can predict which portion of the workpiece would have the exit burr in advance so that we can manage to find a way to minimize the exit burr formation in an actual cutting. Here, the idea of critical burr length is introduced as a criterion in optimization. 相似文献
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A large number of drilling have been performed to assemble aircraft parts of carbon fiber reinforced plastic (CFRP). Although high quality is required in machining the holes with high productivity in terms of reliability of parts, delamination often occurs around the holes in drilling. This paper presents a novel drilling method with variable feed rate to machine the delamination-free holes at a high machining rate. In the drilling, the holes are machined at the standard feed rates when the chisel moves in material; and are finished with the negative thrust at higher feed rates after the chisel exits from the workpiece. Orthogonal cutting tests were conducted to measure the cutting forces and the friction angles for the uncut chip thicknesses and the rake angles. The negative thrusts were measured in large uncut chip thicknesses at large rake angles of the lips. Then, the drilling tests were conducted to verify the change in the cutting force in the variable feed rate drilling up to 100 holes. Negative thrust component appears consistently to raise the workpiece up in the exit process even though the tool wear progresses with repeating drillings. As a result, the variable feed rate drilling remarkably controls delamination compared to the constant feed rate drilling in the 100th drilling. The cutting process in the variable feed rate drilling is compared with the constant feed rate drilling in a cutting force model based on the minimum cutting energy. The negative thrust is verified when the friction angle becomes smaller than the effective rake angle with increasing the feed rate. 相似文献
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W. J. Zong D. Li K. Cheng T. Sun Y. C. Liang 《The International Journal of Advanced Manufacturing Technology》2007,32(7-8):666-674
In this paper, a coupled thermo-mechanical plane-strain large-deformation orthogonal cutting FE model is proposed on the basis
of updated Lagrangian formulation to simulate diamond turning. In order to consider the effects of a diamond cutting tool’s
edge radius, rezoning technology is integrated into this FE based model. The flow stress of the workpiece is modeled as a
function of strain, strain rate, and temperature, so as to reflect its dynamic changes in physical properties. In this way,
the influences of cutting-edge radius, rake angle, clearance angle, depth of cut, and cutting velocity on the residual stresses
of machined surface are analyzed by FE simulation. The simulated results indicate that a rake angle of about 10° and a clearance
angle of 6° are the optimal geometry for a diamond tool to machine ductile materials. Also, the smaller the cutting edge radius
is, the less the residual stresses become. However, a great value can be selected for cutting velocity. For depth of cut,
the ‘size effect’ will be dependent upon it. Residual stresses will be reduced with the decrement of depth of cut, but when
the depth of cut is smaller than the critical depth of cut (i.e., about 0.5 μm according to this work) residual stresses will
decrease accordingly. 相似文献
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Xizhi Sun Kai Cheng 《The International Journal of Advanced Manufacturing Technology》2010,47(9-12):891-901
Molecular dynamics (MD) simulation and the finite element (FE) method are two popular numerical techniques for the simulation of machining processes. The two methods have their own strengths and limitations. MD simulation can cover the phenomena occurring at nano-metric scale but is limited by the computational cost and capacity, whilst the FE method is suitable for modelling meso- to macro-scale machining and for simulating macro-parameters, such as the temperature in a cutting zone, the stress/strain distribution and cutting forces, etc. With the successful application of multi-scale simulations in many research fields, the application of simulation to the machining processes is emerging, particularly in relation to machined surface generation and integrity formation, i.e. the machined surface roughness, residual stress, micro-hardness, microstructure and fatigue. Based on the quasi-continuum (QC) method, the multi-scale simulation of nano-metric cutting has been proposed. Cutting simulations are performed on single-crystal aluminium to investigate the chip formation, generation and propagation of the material dislocation during the cutting process. In addition, the effect of the tool rake angle on the cutting force and internal stress under the workpiece surface is investigated: The cutting force and internal stress in the workpiece material decrease with the increase of the rake angle. Finally, to ease multi-scale modelling and its simulation steps and to increase their speed, a computationally efficient MATLAB-based programme has been developed, which facilitates the geometrical modelling of cutting, the simulation conditions, the implementation of simulation and the analysis of results within a unified integrated virtual-simulation environment. 相似文献
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钛合金切削加工表面残余应力有限元仿真 总被引:2,自引:0,他引:2
采用Johnson- Cook失效准则,建立了钛合金的二维正交切削热-机械应力耦合有限元仿真模型,分析计算了不同切削条件下已加工表面残余应力的分布规律.结果表明:已加工表面层残余应力为拉应力,沿着深度方向由拉应力逐渐过渡到压应力.表面残余应力随着切削速度的增大而增大,在一定的前角变化范围内,随着刀具前角的增大,表面残余拉应力先增大后减小,而随着刀具后角的增大却减小.各加工参数对残余应力层的厚度影响都很小. 相似文献
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应用DEFORM 3D软件对钛合金高速车削进行仿真研究,分析了不同切削参数下切削力和切削温度的规律,研究发现背吃刀量和进给量对主切削力的影响较大,切削力与主切削力变化基本一致,切削速度对主切削力的影响不明显,但后者对切削温度具有显著影响;研究了工件和刀具温度场的变化规律以及工件所受应力和刀具的磨损情况,发现最高温度出现在切削刃邻近2mm区域内,且温度最高处刀具磨损程度最大,工件最大应力在第一变形区和工件接触区邻近。 相似文献