不同侧向间隙下圆盘剪剪切数值模拟与实验研究

以Q235钢为例,运用DEFORM-3D软件,模拟了圆盘剪上下剪刃的侧向间隙分别为0.5mm、1 mm、1.5 mm、2 mm情况下的剪切20 mm厚钢板过程,分析了不同侧向间隙对剪切后的剪切力、钢板断面质量及剪切后钢板应力分布的影响,模拟结果表明过大和过小的侧向间隙会增大剪切力、造成应力分布不均匀并对剪切断面质量有不利的影响,得出了在剪切20 mm厚钢板时最佳侧向间隙为1 mm,并通过现场设定侧向间隙为1 mm对钢板进行剪切,实验结果表明当侧向间隙为1 mm时剪切后的钢板断面质量良好,证明了有限元模拟结果及侧向间隙对剪切过程影响规律的准确性。     

金属板高速剪切断裂数值模拟的研究

针对目前国内常用金属板在剪切过程中剪切效率低、剪切断面质量差及高能耗等问题,提出了一种带有上剪刃几何参数的高速滚切剪剪切方法。重点分析了该种剪切方法对等效剪切应力分布、剪切断面质量和剪切力的影响,并利用DEFORM-3D有限元软件对金属板高速剪切的断裂过程进行了数值模拟研究。模拟结果表明,优化后的高速剪切可以使等效剪切应力比较均匀地分布于剪切区域,并获得了良好的钢板剪切断面质量;与普通滚切剪进行对比,其最大剪切力在切入阶段和滚切阶段均有一定程度的减小,实现了节能剪切的目的。     

剪切速度对棒料剪切断面质量的影响

棒料剪切工艺是多工位冷镦机的第1步工序,坯料的断面质量对后续挤压工序有着重要影响。研究径向不夹紧条件下的棒料剪切工艺,将棒料剪切分为4个过程:初始阶段、棒料倾斜、弹塑性变形和裂纹产生及扩展,分析了每个过程的特点。以20Cr为试验材料,在剪切速度分别为200,400,600和800 mm·s~(-1)的条件下进行棒料剪切试验。定性分析各剪切速度条件下的坯料端断面和棒料端断面的断面形貌,发现随着剪切速度的增大,坯料端光亮带比例逐渐减小,棒料端断面不平度明显减小;定量比较各剪切速度条件下的坯料端断面和棒料端断面的椭圆度与断面倾角,发现随着剪切速度的增大,断面椭圆度逐渐减小,棒料端断面倾角基本不变。     

双切剪剪切过程有限元分析

冷轧连续产线中激光焊机双切剪剪切带钢断面质量对焊缝质量具有重要影响,而焊缝质量的好坏直接影响产线的稳定运行。为此,以某镀锌线激光焊机双切剪为研究对象,通过三维软件对双切剪进行建模,利用有限元软件对剪切过程进行数值模拟,并对比分析了带钢实际剪切断面情况与仿真断面情况、理论剪切力与仿真剪切力、不同剪刃间隙条件下的带钢剪切断面质量。结果表明：带钢仿真剪切断面与实际剪切断面一致;对比2、4、6 mm厚度DP980带钢数值模拟剪切力与诺莎里剪切力公式计算的剪切力,结果相差在5%之内,满足工程实际应用,验证了数值模拟的有效性;通过设定0.05、0.1、0.15 mm 3种不同的剪刃间隙对带钢剪切断面质量进行对比分析,当剪刃间隙为0.05 mm时,带钢剪切断面中剪切带占比最大为42%,毛刺高度最小为0.05 mm,剪切断面质量满足激光焊机对剪切断面的要求,因此在满足工程实际的情况下,剪刃间隙为0.05 mm时带钢剪切断面质量最好。     

马钢CSP取样剪剪切能力分析

首先计算出取样剪在剪切12 mm厚度钢板的总剪切力,然后对剪切机构的位置、剪切机构提供的的剪切力与液压缸行程关系以及剪切过程进行了分析,得到剪切过程的剪切力变化情况。经过比较,证明原取样剪无需改造,即可剪切12 mm厚度的钢板。     

连铸钢方坯液压剪的参数控制及有限元仿真北大核心CSCD

针对传统的液压剪切容易造成连铸钢坯断面质量不佳的问题,提出使用一种45°斜切液压剪进行剪切。首先,建立钢坯和剪刃的剪切模型,利用ANSYS/LS-DYNA软件对45°钢坯液压剪的剪切过程进行了有限元分析,模拟钢坯在弹性变形阶段、塑性变形阶段和断裂分离阶段时所受的等效应力;其次,采取单一变量的研究方法,分别探究了剪切间隙、剪切温度、钢坯厚度及剪切速度等因素对45°钢坯液压剪剪切质量的影响。结果表明,随着剪切间隙的增加,剪切力先减小后增大;钢坯尺寸每增加5 mm,最大剪切力约增加40~50 kN;钢坯剪切速度增加,最大剪切力随之增加,由此获得了最佳的剪切参数,为钢坯的剪切提供了稳定的剪切力,保证了良好的剪切质量,避免材料的损耗,提高了剪切效率。     

φ407mm冷轧圆盘剪切机间隙和重合度对剪切质量的影响分析

针对国内某钢铁企业冷轧线上φ407 mm双边圆盘剪切机剪切厚度为2.82 mm的带钢时出现切边不齐现象,本文利用有限元分析软件对该剪切系统(剪刃和带钢)进行了CAE分析,以此得出了带钢在被剪切位置的应力分布情况,并根据得出的仿真数据结合力学知识,分析了剪刃间隙和重合度对剪切力大小变化的影响以及剪切过程所产生的边界应力对剪切质量的影响.最后通过经验公式证明了数据的可靠性,并提出了改进剪切质量的措施.     

圆盘剪剪切工艺优化研究

基于ANSYS/LS-DYNA有限元模拟软件, 以南京钢铁联合有限公司中板厂Q235钢板剪切过程为研究对象, 研究了在不同工艺参数条件下, 钢板的剪切力和侧向力的变化情况, 分析了不同工艺参数对Q235钢板的剪切力和侧向力的影响。结果表明: 22 mm厚的Q235钢板, 最佳侧向剪切间隙为1.0 mm左右; 随着剪切钢板厚度的增加, 最佳侧向剪切间隙值为钢板厚度的4.55%; 重叠量为-4.5 mm处, 侧向力达到最小值, 为12.893 kN; 剪切力和侧向力也随着剪切速度的增大而增大, 增大幅度为5%～8%。     

双切剪剪切过程有限元分析

以激光焊机双切剪为研究对象,对双切剪的剪切过程进行了简化,建立了双切剪有限元模型;对该模型进行剪切过程模拟,分析了剪切过程中的剪切参数;提取剪切过程4个点,将4个剪切点的剪切参数(包括剪切力,剪切力作用点,作用方向等)提取出来对上下剪进行有限元分析,得出上下剪的应力和变形量。     

大直径薄壁铝合金封头剪切旋压成形研究

应用ABAQUS/Explicit软件平台建立了大直径薄壁铝合金封头剪切旋压成形过程的有限元数值模型,通过数值模拟对大直径薄壁铝合金封头在剪切旋压过程中的应力应变分布进行了分析,获得了工艺参数对成形质量的影响规律为:随旋轮圆角半径R、旋轮进给比f及芯模转速n的增大,旋压件的不均匀变形度呈增大趋势;随旋轮圆角半径、旋轮进给比的增大,旋压件壁厚极小值逐渐减小;随芯模转速提高,壁厚极小值增大,旋压件壁厚极大值对工艺参数的变化不敏感。在此基础上确定了优化工艺参数为:R=12 mm,f=1 mm·r~(-1),n=40 r·min~(-1),并进行剪切旋压成形试验,获得了质量合格的Ф2600 mm大直径薄壁铝合金封头样件。     

Modelling of dynamic cutting coefficients in three-dimensional cutting

A new theory to determine the dynamic cutting coefficients from steady state cutting data for three dimensional cutting has been developed. It is based on direct measurements of cutting forces, without any hypothesis relating to the steady state cutting. The experimental results show fairly good coincidence with the theoretical prediction of the stability limit.     

Three-dimensional cutting process analysis with different cutting velocities

This paper uses the large deformation large strain finite-element theory, the updated Lagrangian formulation and the incremental theory approach to develop a 3D elastic-plastic analytical model that examines metal cutting on the tool tip and twin nodes on the machined face. The geometric position and the critical value of strain energy density, combined with twin node treatment, are also introduced to serve as the continuous chip separation criterion.

Finally, the 3D low-velocity cutting condition of mild steel was explored to analyze changes in the appearances of the workpiece and the chip, the distribution of stress and strain, and the progress of changes in the cutting force. The impact of different cutting velocities and the initial conditions of the residual stress were studied to understand the impact of various cutting conditions on the machined workpiece. The numerical average cutting forces are compared with the experimental cutting forces with the different low-cutting velocities to verify that the 3D cutting model that has been developed is reasonable.     

陶瓷刀具在干切削加工中的应用

文章论述了陶瓷刀具的特点和切削性能,对陶瓷刀具在干切削中的使用进行了分析.     

Identification of the specific cutting force for geometrically defined cutting edges and varying cutting conditions

Cutting force modeling is a major discipline in the research of cutting processes. The exact prediction of cutting forces is crucial for process characterization and optimization. Semi-empirical and mechanistic force models have been established, but the identification of the specific cutting force for a pair of tool and workpiece material is still challenging. Existing approaches are depending on geometrical idealizations and on an extensive calibration process, which make practical and industrial application difficult. For nonstandard tools and five axis kinematics there does not exist a reasonable solution for the identification problem.In this paper a co-operative force model for the identification of the specific cutting forces and prediction of integral forces is presented. The model is coupled bidirectionally with a multi-dexel based material removal model that provides geometrical contact zone information. The nonlinear specific forces are modeled as polynomials of uncut chip thickness. The presented force model is not subjected to principal restrictions on tool shape or kinematics, the specific force and phase shift are identified with help of least square minimization. The benefit of this technique is that no special calibration experiments are needed anymore, which qualifies the method to determine the specific forces simultaneously during the machining process. In this paper, experiments with different cutting conditions are analyzed and systematically rated. Finally, the method is validated by experiments using different cutting conditions.     

The effect of vibration cutting on minimum cutting thickness

In the ultra-precision diamond cutting process, the rake angle of the tool becomes negative because the edge radius of a tool is considerably larger compared to the sub-micrometer depth of the cut. The effects of plowing due to the large negative rake angle result in an unstable cutting process without continuous chip. For this reason, it is important to determine minimum cutting thickness in order to enable greater machining accuracy to be obtained by fine and stable machining. It was previously reported that the critical depth of cut with a continuous chip was determined by the tool sharpness and the friction coefficient between a workpiece and a tool [S.M. Son, et al., Effects of the friction coefficient on the minimum cutting thickness in micro cutting, International Journal of Machine Tools and Manufacture 45 (2005) 529–535]. For the same edge radius of a tool, the higher the friction coefficient of the tool–workpiece, the thinner the minimum cutting thickness becomes. Therefore, it is believed that increasing the friction coefficient by a physical method would be effective to achieve thinner stable cutting. In this study, the possibility of reducing the minimum cutting thickness was investigated through changing the friction coefficient of a tool–workpiece. The vibration cutting method is applied to increase the friction coefficient. Experimental results show that the cutting technology is efficient for increasing the friction coefficient and decreasing the minimum cutting thickness. The minimum cutting thickness was reduced by about 0.02–0.04 μm depending on materials and vibration conditions.     

切削温度与切削力综合测量的虚拟仪器

介绍了综合测量切削平均温度和三向切削力并对其进行分析处理的虚拟仪器.利用PCI-1 200卡采集热电偶测温仪和电阻应变式测力仪传输的数据.利用LabVIEW平台开发.具有显示 力和温度波形曲线、热电偶标定和测力仪刻度标定、确定切削温度和切削力指数公式的能力 .提出了基于切削力和切削温度信息的切削状态判定方法.     

自动切管机切割路径的运动学分析

切管机是管材加工及应用行业的专用加工设备,管材的管-板相贯的几何特点给切割一次成形带来了很大的困难,基于一次成形的考虑,提出了管-板相贯求交的一个通用算法,根据这一算法设计的数控切管机成功地实现了这类坡口一次数控切割成形,并通过一个较为典型的例子作一详细的论述.     

切削温度与切削力综合测量的虚拟仪器

介绍了综合测量切削平均温度和三向切削力并对其进行分析处理的虚拟仪器。利用PCI－1200卡采集热电偶测温仪和电阻应变式测力仪传输的数据。利用Lab VIEW平台开发。具有显示力和温度波形曲线、热电偶标定和测力仪刻度标定、确定切削温度和切削力指数公式的能力。提出了基于切削力和切削温度信息的切削状态判定方法。