共查询到20条相似文献,搜索用时 15 毫秒
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张琳 《锻压装备与制造技术》2014,49(6):54-57
针对直齿圆锥齿轮精锻成形中齿形充填不满及成形力过大导致模具损伤等问题,制定了中心分流法精锻直齿圆锥齿轮的工艺方案.以工艺方案和数值模拟结果为依据,设计了预锻分流区和分流终锻两套模具,并对精锻模具的模膛和结构设计要点进行了阐述. 相似文献
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This paper presents a tri-dexel geometric engine integrated simulation model for the gear hobbing operation. The process kinematics are modeled and validated using CNC signals from a Liebherr LC500 hobbing machine. Workpiece geometry updating and cutter-workpiece engagement (CWE) calculations are efficiently realized in the tri-dexel engine. 3D force contributions at discretized nodes along the hob's cutting edges are computed considering the localized principal cutting directions, and rake and inclination angles. To measure cutting forces, a rotary dynamometer is successfully adapted and used alongside a Kalman filter to compensate for structural dynamics. The predicted forces agree well with their experimental counterparts. 相似文献
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S. K. Choudhury I. V. K. Appa Rao 《International Journal of Machine Tools and Manufacture》1999,39(2):1354
Optimum use of the cutting tool is a growing need in modern industries since the cost of production is directly affected by this. This paper presents a new approach for improving the cutting tool life by using optimal values of velocity and feed throughout the cutting process. A tool life equation has been established from experimental data and the adhesion wear model. Optimization techniques have been used to maximize the tool life subject to practical constraints while maintaining a constant metal removal rate. The experimental results showed an improvement in tool life by 30%. 相似文献
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Geometric error measurement of spiral bevel gears using a virtual gear model for STEP-NC 总被引:1,自引:0,他引:1
S. H. Suh E. S. Lee H. C. Kim J. H. Cho 《International Journal of Machine Tools and Manufacture》2002,42(3)
Geometric error measurement is required to evaluate the grade of the manufactured gears. Due to the complexity of the spiral bevel gear, direct measurement with the physical part has been conducted in a very limited way. In this paper, we present an indirect measurement based on the virtual gears model (VGM), obtained by NUBS fitting of the surface points measured by CMM (coordinate measuring machine). By comparing the VGM with CAD model (soft-master model), various errors such as tooth profile error and tooth trace error can be automatically measured. The developed method is simple and robust without requiring a special measuring device, and hence it can be applied for the industrial practice as a means for measuring the tooth profile and tooth trace errors which cannot be measured by the conventional method. Further, the model-based method can be incorporated on the advanced CNC controller based on the new CAM–CNC interface scheme of STEP-NC [STEP (standard for transfer and exchange of product model data) based data model for CAM and CNC interface] as an on-line inspection module. Algorithmic details together with experimental validation results are given. 相似文献
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Takashi Matsumura Eiji Usui 《International Journal of Machine Tools and Manufacture》2010,50(5):467-473
The cutting force and the chip flow direction in peripheral milling are predicted by a predictive force model based on the minimum cutting energy. The chip flow model in milling is made by piling up the orthogonal cuttings in the planes containing the cutting velocities and the chip flow velocities. The cutting edges are divided into discrete segments and the shear plane cutting models are made on the segments in the chip flow model. In the peripheral milling, the shear plane in the cutting model cannot be completely made when the cutting point is near the workpiece surface. When the shear plane is restricted by the workpiece surface, the cutting energy is estimated taking into account the restricted length of the shear plane. The chip flow angle is determined so as to minimize the cutting energy. Then, the cutting force is predicted in the determined chip flow model corresponding to the workpiece shape. The cutting processes in the traverse and the contour millings are simulated as practical operations and the predicted cutting forces verified in comparison with the measured ones. Because the presented model determines the chip flow angle based on the cutting energy, the change in the chip flow angle can be predicted with the cutting model. 相似文献
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A cutting power model for tool wear monitoring in milling 总被引:4,自引:2,他引:4
H. Shao H. L. Wang X. M. Zhao 《International Journal of Machine Tools and Manufacture》2004,44(14):1503-1509
This paper describes a cutting power model in face milling operation, where cutting conditions and average tool flank wear are taken into account. The cutting power model is verified with experiments. It is shown with the simulations and experiments that the simulated power signals predict the mean cutting power better than the instantaneous cutting power. Finally, the cutting power model is used in a cutting power threshold updating strategy for tool wear monitoring which has been carried out successfully in milling operations under variable cutting conditions. 相似文献
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David W. Smithey Shiv G. Kapoor Richard E. DeVor 《International Journal of Machine Tools and Manufacture》2000,40(13)
Previous studies have shown that there is a region on the flank of a worn cutting tool where plastic flow of the workpiece material occurs. This paper presents experimental data which shows that in three-dimensional cutting operations in which the nose of the tool is engaged, the region of plastic flow grows linearly with increases in total wearland width. A piecewise linear model is developed for modeling the growth of the plastic flow region, and the model is shown to be independent of cutting conditions. A worn tool force model for three-dimensional cutting operations that uses this concept is presented. The model requires a minimal number of sharp tool tests and only one worn tool test. An integral part of the worn tool force model is a contact model that is used to obtain the magnitude of the stresses on the flank of the tool. The force model is validated through comparison to data obtained from wear tests conducted over a range of cutting conditions and workpiece materials. It is also shown that for a given tool and workpiece material combination, the incremental increases in the cutting forces due to tool flank wear are solely a function of the amount and nature of the wear and are independent of the cutting condition in which the tool wear was produced. 相似文献
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焊点可靠性预测研究多采用有限元仿真与单一精度近似模型相结合的模式,存在仿真时间长、效率低、准确性差等问题,为此,提出了一种基于变可信度近似模型的球栅阵列(ball grid array,BGA)焊点可靠性预测与优化方法.首先, 对不同网格细化方案进行收敛性验证,分别设计高/低精度样本点进行有限元仿真;其次,基于Co-Kriging模型融合高/低精度仿真数据进行焊点可靠性预测;最后,将预测结果与单一精度近似模型进行对比分析,并采用遗传算法优化模型获得对应结构参数.结果表明,在更少的仿真成本下,变可信度模型的预测效果更好,在同等预测精度下,变可信度模型高精度样本点数量仅为单一精度模型的1/4,相比高精度神经网络预测模型,在寻优过程中收敛更快.
相似文献15.
Nickel-based superalloys are easy to produce low cycle fatigue (LCF) damage when they are subjected to high temperature and mechanical stresses. Fatigue life prediction of nickel-based superalloys is of great importance for their reliable practical application. To investigate the effects of total strain and grain size on LCF behavior, the high temperature LCF tests were carried out for a nickel-based superalloy. The results show that the fatigue lives decreased with the increase of strain amplitude and grain size. A new LCF life prediction model was established considering the effect of grain size on fatigue life. Error analyses indicate that the prediction accuracy of the new LCF life model is higher than those of Manson-Coffin relationship and Ostergren energy method. 相似文献
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Balkrishna C. Rao Yung C. Shin 《International Journal of Machine Tools and Manufacture》1999,39(10):1631
This paper presents a model of the dynamic cutting force process for the three-dimensional or oblique turning operation. To obtain dynamic force predictions, the mechanistic force model is linked to a tool–workpiece vibration model. Particular attention was paid to the inclusion of the cross-coupling between radial and axial vibrations in the force model. The inclusion of this cross-coupling facilitates prediction of the unstable–stable chatter phenomenon which usually occurs in certain cases of finish turning due to process non-linearity. The dynamic force model developed was incorporated into a computer program to obtain time-saving chatter predictions. Experimental tests were performed on AISI 4140 steel workpieces to justify the chatter predictions of the dynamic cutting process model in both the finishing and roughing regimes. Experimental results corroborate the unstable–stable chatter predictions of the model for different cases of finish machining. In addition, experimental results also confirmed the accuracy of chatter predictions for various cases of rough turning. 相似文献
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为建立焊趾疲劳裂纹萌生行为仿真方法,基于 Roe-Siegmund 循环内聚力模型对 ABAQUS 进行二次开发,形成用于反映疲劳累积损伤的VUMAT子程序,依据文献方法及试验数据获取Q345焊接区域材料的内聚力参数,通过Voronoi图法和内聚力单元法生成具有疲劳累积损伤特性和晶粒特征的微观模型,并与宏观对接焊缝模型合并,进行多尺度疲劳裂纹萌生仿真模拟,获得裂纹萌生路径、临界循环次数及晶粒力学响应特征. 结果表明,此方法能够自发地选择符合实际情况的裂纹萌生位置以及短裂纹扩展路径,完成对焊接区域材料微观断裂过程的模拟,不同仿真组获取的临界循环次数存在于一定的分布范围内,模型中的累积内聚力长度需通过试验数据进行拟合.
相似文献19.
为了准确预测材料的疲劳寿命,提高结构疲劳寿命预测精度,对ABAQUS有限元数值模拟预测试样疲劳寿命的方法进行了研究. 基于Tanaka-Mura位错理论,利用python语言对ABAQUS进行二次开发,模拟预测了S960QL马氏体钢和Ti2AlNb钛合金接头各区域疲劳裂纹萌生寿命. 利用泰森多边形法生成了晶体特征单元建立了微观子模型,考虑了体心立方结构相互垂直的两条滑移带作为潜在的裂纹萌生位置,并对具有相同取向的多条平行滑移带都进行了模拟计算. 通过计算得到的裂纹扩展速率变化,给出了裂纹萌生阶段过渡到裂纹扩展阶段的临界点处的裂纹萌生寿命. 模拟结果表明,除焊缝柱状晶组织外裂纹萌生寿命与试验数据吻合良好. 相似文献