Advances in Machining and Manufacturing Technology XII

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Authors: Kui Hu Cui, Cheng Zu Ren, Guang Chen
Abstract: In this paper, an advanced 3D FE model was established using ABAQUS Explicit to simulate the process of milling aluminum-alloy 7075-T7451. Taking the end edge and the side edge of single flute into consideration, the model simulated the interaction between the spiral flute and wokpiece at full depth of cut. In addition, by defining automatic element deletion criterion and locally refining mesh, this model realized chip separating from workpiece without defining of cutting layer. The simulation results were compared with experimental data to verify the correctness of the simulation model.
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Authors: Guo Sheng Su, Zhan Qiang Liu
Abstract: In this paper, the specific shear energy in high-speed machining 7050-T7451 from 100m/min to 3000m/min is measured and compared with the theoretical value evaluated by the method proposed by Pawade et al. (2009). The influences of cutting speed, rake angle of cutting tool, and uncut chip thickness are also investigated and discussed. Results show that the specific shear energy decreases with the increase of cutting speed, rake angle, and uncut chip thickness. The higher thermal softening makes the specific shear energy lower.
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Authors: Song Zhang, Jian Feng Li, Hong Gang Lv, Wei Dong Chen
Abstract: In the present research, an attempt has been made to experimentally investigate the cutting forces in hard milling of H13 steel with coated carbide tools under dry, MQL (minimum quantity lubrication) and MQCL (minimum quantity cooling lubrication) cutting conditions. Based on Taguchis method, four-factor (cutting speed, feed per tooth, radial depth of cut, and axial depth of cut) four-level orthogonal experiments were employed. It is found that the periodical fluctuation of the cutting forces caused by the variation of the undeformed chip thickness with the entry/exit of the cutting edge is an essential feature of the hard milling process. The empirical models for cutting forces are established, and ANOVA (analysis of variance) indicates that the quadratic models can well express the relationship between cutting forces and cutting parameters.
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Authors: Lu Ning Liu, Zhen Yu Shi, Zhan Qiang Liu
Abstract: In this paper, a face-milling tool system is dealt with the Finite Element Modal Analysis (FEMA) using advanced contact technology functionalities. Dynamic characteristics analysis is performed and the stiffness contribution is included in the modal pre-stressed analysis. Natural frequencies and mode shapes of vibration are calculated. The FEMA is followed by experiments performed for different operating conditions of the face-milling system. The dynamic characteristics obtained in this paper can be used to optimize the face-milling cutter in high speed machining.
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Authors: Dong Wang, Jun Zhao, Xiao Xiao Chen, Yong Hui Zhou
Abstract: An experimental investigation of wear mechanisms in high-speed turning of superalloy GH2132 with Al2O3-based ceramic was conducted under dry cutting condition. The tool wear mechanisms were characterized by observation of tool wear morphology using scanning electron microscopy (SEM) and detection of the element distribution of the worn tool surface utilizing energy dispersive X-ray spectroscopy (EDS). The results of turning experiments indicated that the major wear mechanisms of the ceramic cutting tool were synergistic interaction between abrasive wear and adhesive wear, and meanwhile the micro-chipping was also observed. It is also shown that cutting distance of the Al2O3-TiC ceramic cutting tool at the speed of 420 m/min was higher than that of the speed of 360 m/min and 540 m/min.
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Authors: Sha Liu, Ping Fa Feng, Ding Wen Yu
Abstract: This paper proposes a method to simulate residual stress induced by end milling process via 3-D FEM. First, Johnson-Cook material model parameters for a Japanese type of alloy steel (SCM440H) were extracted by a combination method. With the material model parameters, symmetrical end milling process for plate of SCM440H was simulated by FE software to get the residual stress distribution in the machined workpiece. Residual stress measurement experiment was carried out after end milling process to be compared with simulation result to verify the method, which proved that high simulation accuracy can be obtained by extracted material model parameters.
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Authors: Cai Xu Yue, Xian Li Liu, Jing Ma, Xue Liu, Guang Xu Ren
Abstract: After hard cutting process, processed surface residual stress distribution state has a significantly effect on life of parts. In this paper, typical mold steel Cr12moV as the object of study, after the hard state processing in different cutting parameters and tool parameters, effects of different cutting parameters and tool parameters on surface residual stress and residual stress affected layer. Results showed that different cutting parameters and tool parameters can make different tensile stress distributing on surface, and the residual surface stress is can also be compressive stress. Through the experiment can be found with greater speed, cutting tool wear is bigger, the machined surface residual compressive stress and affected layer depth and when the tool flank wear is greater than 0.3mm, also the surface residual stress distribution curve downward obviously. The research results provide reference for optimization of processing conditions.
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Authors: Gang Liu, Ming Chen, Peng Nan Li, Qing Zhen Bi, Bao Cai Guo
Abstract: The concept of multi-constrained analysis of the cutting process is presented for the first time in the paper. The paper adopts a method to solve an important problem which is how to judge the influence of constrains during the cutting process. The research results are applied for HSS drills for cutting stainless steel. On the basis of the multi-constrained analysis combined with methods of simulations and standard experiments, the optimum methods are provided for structure, coating and cutting parameters of cutting tools. For geometric structure of tools, optimization is to increase thickness of cutting and rake angle. Coating optimization strategy is choosing high temperature hardness and low thermal conductivity coating. Optimization of cutting parameter is to adjust feed fate, then select proper cutting speed. The conclusion of paper is helpful for the cutting optimization.
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Authors: Li Na Zhang, Peng Nan Li, Si Wen Tang, Wen Bo Tang, Shuai Zhang
Abstract: The stress-strain curves, mechanical behaviors, and Johnson-Cook model of 4Cr13 stainless steel were investigated at both the strain rates from 0.001s-1 to 7000s-1 and the temperatures from 293K to 673K based on the electronic universal testing machine and the split Hopkinson bar. The results showed that 4Cr13 stainless steel was very sensitive to the temperature and the strain rate. The temperature sensitivity factor decreased with increasing the temperature, and the strain rate sensitivity factor increased with increasing the strain rate. Both the temperature sensitivity factor and strain rate sensitivity factor decreased with increasing strain. The flow stress increased with strain rate and strain, but decreased with temperature. The J-C model prediction had a good agreement with the experimental stress-strain in the wide range of temperatures and strain rates. The Johnson-Cook model gave the foundation for finite element analysis during the cutting process.
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