共查询到18条相似文献,搜索用时 125 毫秒
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《计算机集成制造系统》2015,(6)
为了评估金属切削刀具的可靠性,提出了机床切削刀具可靠度和平均寿命的概率评估方法,利用马尔科夫链蒙特卡洛法解决了描述刀具故障率的Weibull比例危险模型参数贝叶斯点估计及区间估计难题,所提评估方法可给出刀具可靠度、故障率、平均寿命及其下限的估计值。通过实例分析表明:刀具可靠度随切削用量和切削时间的变化非单调下降,而平均寿命随切削用量的变化而波动变化。所提方法综合考虑了切削用量和验前经验,给出的刀具可靠度和平均寿命估计更符合实际加工条件。 相似文献
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机床刀具故障往往是在多种失效原因的共同作用下发生,不同加工时段故障数据分布不同。为了准确评估刀具的可靠性,综合考虑切削用量等因素的影响,采用混合Weibull分布并结合比例危险模型对刀具故障数据进行建模。所得模型参数较多,用马尔科夫链蒙特卡洛仿真方法解决了模型参数估计难题。该方法可给出刀具可靠度、平均寿命、刀具寿命标准差、故障率及平均剩余寿命等可靠性指标。通过对一工程实例进行分析,展示了该模型的应用价值。 相似文献
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钻削直径在φ22mm以下的深孔广泛地使用装有硬质合金刀片和引导部分的单面切削刀具。它适于向刀具内部输送润滑冷却液,但是它的制造和使用水平还不适宜于采用较大的切削用量。典型结构的单面切削刀具由刀杆和镶有硬质合金块的切削刃与两个引导组成。在刀头上开有输送润滑冷却液的通道,硬质合金块以楔形面同刀杆相联接。刀具的刀杆和整块硬质合金工作部分都采用120°扇形横截面的V形结构,但是这种刀具不能满足提高切削用量的要求。列宁格勒机械学院实验室从对难加工钢深孔钻削进行多次强化试验,得出用刀具的最佳参数来加工直径10~22mm的孔以提高抗振性和工艺可靠性。一种 相似文献
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刀具寿命变异系数是评价刀具可靠性的重要指标之一.本文通过切削试验,从工件材料、刀具几何角废、刀具磨钝标准及切削用量等方面全面探讨了影响刀具寿命变异系数的各种因。提出了降低刀具寿命变异系数,提高刀具可靠性达到加工经济性的途径. 相似文献
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通过对数控机床加工情况的现场调查,验证了关于刀具磨损寿命分布规律的研究成果,分析了刀具可靠性对切削加工过程的影响,建立了应根据刀具的可靠性来决定换刀间隔和切削用量,并提出了提高刀具可靠性的具体措施。 相似文献
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恒定加工条件及定期补偿下的刀具渐变可靠性灵敏度分析方法 总被引:4,自引:0,他引:4
据统计,由刀具失效导致的停机时间超过机床被迫停机时间的1/3,故开展刀具渐变可靠性及其灵敏度分析的研究对提高机床的运行可靠性具有重要意义。采用连续时间、连续状态、具有非减独立增量的非平稳Gamma过程描述刀具磨损量的变化过程。根据加工偏差不大于机床给定加工精度的原则,构建刀具制造及磨损量检测有无误差两种情形下、恒定加工条件及定期补偿的刀具渐变状态函数,由此推导出相应的渐变可靠度模型。在此基础上给出渐变可靠度模型对各个参数的灵敏度计算方程。通过数值实例分析,阐述了通过提出的渐变可靠性模型及灵敏度分析方法提高刀具运行可靠性的应用过程。这一工作为提高恒定加工条件及定期补偿下刀具的运行可靠性提供切实可行的理论和方法基础。 相似文献
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以0Cr18Ni9耐热钢为研究对象进行车削试验,得出切削用量对刀具耐用度的影响规律,确定每种刀具的最佳切削速度,分析了刀具磨损破损机理。 相似文献
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Influence of geometric and cutting parameters of cemented carbide cutting tool on reliability of cutting tool has become more and more mature, yet influence of its physical and material parameters on reliability is still blank. In view of this, cutting test and fatigue crack growth test of YT05 cemented carbide cutting tool are conducted to measure such data as the original crack size, growth size, times of impact loading, number and time of cutting tool in failure, and stress distribution of cutting tool is also obtained by simulating cutting process of tools. Mathematical models on dynamic reliability and dynamic reliability sensitivity of cutting tool are derived respectively by taking machining time and times of impact loading into account, thus change rules of dynamic reliability sensitivity to physical and material parameters can be obtained. Theoretical and experimental results show that sensitive degree on each parameter of tools increases gradually with the increase of machining time and times of impact loading, especially for parameters such as fracture toughness, shape parameter, and cutting stress. This proposed model solves such problems as how to determine the most sensitive parameter and influence degree of physical parameters and material parameters to reliability, which is sensitivity, and can provide theoretical foundation for improving reliability of cutting tool system. 相似文献
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K. Kadirgama K. A. Abou-El-Hossein B. Mohammad H. Habeeb 《Journal of Mechanical Science and Technology》2007,21(10):1651-1655
The aim of this study is to develop the surface roughness prediction models, with the aid of statistical methods, for hastelloy
C-22HS when machined by PVD and CVD coated carbide cutting tools under various cutting conditions. These prediction models
were then compared with the results obtained experimentally. By using response surface method (RSM), first order models were
developed with 95 % confidence level. The surface roughness models were developed in terms of cutting speed, feed rate and
axial depth using RSM as a tool of design of experiment. In general, the results obtained from the mathematical models were
in good agreement with those obtained from the machining experiments. It was found that the feed rate, cutting speed and axial
depth played a major role in determining the surface roughness. On the other hand, the surface roughness increases with a
reduction in cutting speed. PVD coated cutting tool performs better than CVD when machining hastelloy C-22HS. It was observed
that most of the chips from the PVD cutting tool were in the form of discontinuous chip while CVD cutting tool produced continuous
chips. 相似文献
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通过数控加工工艺特点分析,提出数控刀具的技术要求。并分析数控刀具损坏形式,提出了数控刀具的可靠度概念、性质及刀具耐用可靠度,介绍改善数控刀具耐用可靠度的优化要点。 相似文献
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Ziling Zhang Zhifeng Liu Ligang Cai Qiang Cheng Yin Qi 《The International Journal of Advanced Manufacturing Technology》2017,91(5-8):1547-1566
Accuracy design constitutes an important role in machine tool designing. It is used to determine the permissible level of each error parameter of a machine tool, so that any criterion can be optimized. Geometric, thermal-induced, and cutting force-induced errors are responsible for a large number of comprehensive errors of a machine tool. These errors not only influence the machining accuracy but are also of great importance for accuracy design to be performed. The aim of this paper is the proposal of a general approach that simultaneously considered geometric, thermal-induced, and cutting force-induced errors, in order for machine tool errors to be allocated. By homogeneous transformation matrix (HTM) application, a comprehensive error model was developed for the machining accuracy of a machine tool to be acquired. In addition, a generalized radial basis function (RBF) neural network modeling method was used in order for a thermal and cutting force-induced error model to be established. Based on the comprehensive error model, the importance sampling method was applied for the reliability and sensitivity analysis of the machine tool to be conducted, and two mathematical models were presented. The first model predicted the reliability of the machine tool, whereas the second was used to identify and optimize the error parameters with larger effect on the reliability. The permissible level of each geometric error parameter can therefore be determined, whereas the reliability met the design requirement and the cost of this machining was optimized. An experiment was conducted on a five-axis machine tool, and the results confirmed the proposed approach being able to display the accuracy design of the machine tool. 相似文献
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Taghi Feyzi S. Mohsen Safavi 《The International Journal of Advanced Manufacturing Technology》2013,66(5-8):1025-1030
In this paper, by joining three non-traditional machining methods — plasma-enhanced machining, cryogenic machining, and ultrasonic vibration assisted machining — a new hybrid machining technique for machining of Inconel 718 is presented. Cryogenic machining reduces the temperature in the cutting zone, and therefore decrease tool wear and increases tool life, while plasma-enhanced machining helps to increase the temperature in the workpiece to make it softer. Also, applying ultrasonic vibrations to the tool helps to improve cutting quality and to prolong tool life by lowering, mainly, the cutting force and improving the dynamic cutting stability. This study experimentally investigates the effect of cutting parameters on cutting performance in the machining of Inconel 718 and compares the results of hybrid machining and conventional machining (CM). It is found that the hybrid method results in better surface finish and improves tool life in hard cutting at low cutting speeds as compared to the CM method. 相似文献
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Marwa Ayadi Nabil Derbel 《The International Journal of Advanced Manufacturing Technology》2017,91(1-4):39-48
Tool wear degradation and working status of slotting cutter have a great effect on the surface quality of rotor slot; therefore, tool condition monitoring and its degradation estimation are needed for guaranteeing slot machining quality. This paper proposes a two-phase method based on acoustic emission (AE) signal classification and logistic regression model for slotting cutter condition monitoring and its degradation estimation. In the first phase, the failure reliability estimation models corresponding to different machining processes are established considering the variability of process system like tool regrinding times and material randomness of workpiece. In the second phase, the most appropriate estimation model corresponding to the optimum cluster is selected and used for failure reliability estimation and status determination of slotting cutter. This approach has been validated on a CNC rotor slot machine in a factory. Experimental results show that the proposed method can be effectively used for cutting tool degradation estimation and status determination of slotting cutter with high accuracy. 相似文献
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Mehmet Alper Sofuoğlu Fatih Hayati Çakır Selim Gürgen Sezan Orak Melih Cemal Kuşhan 《The International Journal of Advanced Manufacturing Technology》2018,95(1-4):83-97
Ultrasonic-assisted machining is a machining operation based on the intermittent cutting of material which is obtained through vibrations generated by an ultrasonic system. This method utilizes low-amplitude vibrations with high frequency to prevent continuous contact between a cutting tool and a workpiece. Hot machining is another method for machining materials which are difficult to cut. The basic principle of this method is that the surface of the workpiece is heated to a specific temperature below the recrystallization temperature of the material. This heating operation can be applied before or during the machining process. Both of these operations improve machining operations in terms of workpiece-cutting tool characteristics. In this study, a novel hybrid machining method called hot ultrasonic-assisted turning (HUAT) is proposed for the machinability of Hastelloy-X material. This new technique combines ultrasonic-assisted turning (UAT) and hot turning methods to take advantage of both machining methods in terms of machining characteristics, such as surface roughness, stable cutting depths, and cutting tool temperature. In order to observe the effect of the HUAT method, Hastelloy-X alloy was selected as the workpiece. Experiments on conventional turning (CT), UAT, and HUAT operations were carried out for Hastelloy-X alloy, changing the cutting speed and cutting tool overhang lengths. Chip morphology was also observed. In addition, modal and sound tests were performed to investigate the modal and stability characteristics of the machining. The analysis of variance (ANOVA) method was performed to find the effect of the cutting speed, tool overhang length, and machining techniques (CT, UAT, HUAT) on surface roughness, stable cutting depths, and cutting tool temperature. The results show both ultrasonic vibration and heat improve the machining of Hastelloy-X. A decrease in surface roughness and an increase in stable cutting depths were observed, and higher cutting tool temperatures were obtained in UAT and HUAT compared to CT. According to the ANOVA results, tool overhang length, cutting speed, and machining techniques were effective parameters for surface roughness and stable cutting depths at a 1% significance level (p ≤ 0.01). In addition, cutting speed and machining techniques have an influence on cutting tool temperature at a 1% significance level (p ≤ 0.01). During chip analysis, serrated chips were observed in UAT and HUAT. 相似文献