共查询到20条相似文献,搜索用时 0 毫秒
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Vipin Kumar Sharma Vinod Kumar Ravinder Singh Joshi 《Machining Science and Technology》2020,24(1):42-64
AbstractIn present research work, ultrafine-grained strips of Al-6063 alloy were fabricated using hybrid extrusion machining technique known as “large strain extrusion machining (LSEM).” Fabrication of strips was done using the customized HSS tools of different rake angles varying from 0° to 10° under different machining conditions. Microstructural and mechanical characterizations of these strips were done to ascertain the effect of different parameters on their properties. From the results of hardness measurement of strips, it was concluded that hardness of the strips increased by 34–97% of the base material as of the refinement of grain size occurred. Surface lay was improved by 30% with higher cutting velocity and rake angle. Crystallite size was found to decrease with increase in the rate of strain. The shear strain was increased as chip compression ratio increased and rake angle decreased. Fabrication ability of strips increased due to increase in strain hardening exponent and it may result in the large scope of their applications. Nano-hardness of the strips was found to be more than bulk alloy. These above said results showed that ultrafine strips fabricated using LSEM process can become a good choice for future material fabrication. 相似文献
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HALINA GARBACZ MAGORZATA LEWANDOWSKA WACAW PACHLA† & KRZYSZTOF J. KURZYDOWSKI 《Journal of microscopy》2006,223(3):272-274
The aim of the present study was to examine the potential of hydrostatic extrusion for the fabrication of high‐strength materials for medical applications. The materials examined were 316LVM steel and technically pure titanium. The microstructures and mechanical properties of the materials before and after hydrostatic extrusion were analysed. It was found that the hydrostatic extrusion process resulted in a substantial refinement of the material microstructures. The refinement of the microstructure was accompanied by an improvement of the mechanical properties, such as the microhardness and yield stress. 相似文献
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According to the established thermal theories on electro-discharge machining (edm), the size of the craters produced in edm is proportional to the discharge energy, which is equal to the product of mean pulse current and pulse duration for a constant gap voltage. As a practical edm surface is a random superposition of such craters, the behaviour of the surfaces largely depends on the two important parameters, pulse current and pulse duration. With the help of multiple linear regression analysis, the effect of pulse duration and pulse current on the surface topography parameters Rq and β* has been studied. sem photomicrographs have been taken in support of the qualitative evidence 相似文献
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介绍了在普通车床上应用滚压技术加工船舶艉轴等轴类零件的过程,该方法操作简单,解决了轴表面粗糙度和形位公差要求高的技术难题,可供相关工程技术人员参考。 相似文献
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In machining, cutting tools suffer from severe surface wear, especially in the cutting of difficult-to-cut materials. A major cause of tool wear is the friction generated at the tool-work and tool-chip interfaces, which produces a great deal of frictional heat and abrasion. In order to extend tool life and improve the quality of machined components, a host of techniques have been applied to modify the rake and flank faces of cutting tools. These techniques aim at providing cutting tools with improved resistance to external loading, better tribological performance and/or better chemical stability. This article presents a review of the fundamentals behind which the friction and wear in machining are reduced by modifying the cutting tool surface with the commonly used techniques, such as surface coating, high energy beam treatment, and surface texturing. The effects of these surface modifications on improving the cutting performance are also analyzed. Future research directions are finally discussed. 相似文献
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M. Agmell A. Ahadi J. M. Zhou R. L. Peng V. Bushlya J.-E. Ståhl 《Machining Science and Technology》2017,21(1):103-120
Traditionally, the development and optimization of the machining process with regards to the subsurface deformation are done through experimental method which is often expensive and time consuming. This article presents the development of a finite element model based on an updated Lagrangian formulation. The numerical model is able to predict the depth of subsurface deformation induced in the high- speed machining of Inconel 718 by use of a whisker-reinforced ceramic tool. The effect that the different cutting parameters and tool microgeometries has on subsurface deformation will be investigated both numerically and experimentally. This research article also addresses the temperature distribution in the workpiece and the connection it could have on the wear of the cutting tool. The correlation of the numerical and experimental investigations for the subsurface deformation has been measured by the use of the coefficient of determination, R2. This confirms that the finite element model developed here is able to simulate this type of machining process with sufficient accuracy. 相似文献
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《Lubrication Science》2017,29(7):493-501
The aim of the present research work was to investigate the effectiveness of grooved surface texturing with a rhombic geometry under different lubrication regimes. Tribological investigation under unidirectional sliding was focused on the effect of texturing parameters including pattern area density on the coefficient of friction under different lubrication regimes, achieved by varying sliding speed and lubricant viscosity. Grooved patterns with different textured area densities were produced on steel samples by electrical discharge machining. Results of this investigation showed that under boundary lubrication, textures resist sliding thus resulting in increased friction. The largest improvement of friction reduction was observed under hydrodynamic lubrication, for low‐viscosity oil when using the textured disc with 21% pattern area density. The reduction of the coefficient of friction if compared with the untextured surface was of approximately 24%. Examination of the sliding surfaces has not shown any quantifiable wear for the contact conditions studied. 相似文献
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Research on the localisation of the workpieces with large sculptured surfaces in NC machining 总被引:4,自引:1,他引:4
Y. Sijie Z. Yunfei P. Fangyu L. Xide 《The International Journal of Advanced Manufacturing Technology》2004,23(5-6):429-435
Localisation of workpieces with large sculptured surfaces can be difficult. Previously, such pieces were measured by the probe of the machine and adjusted manually. This process is arduous and time-consuming and an even allowance cannot be ensured for every measured point. Searching for the optimal location of surface matching by computer can realise computer aided localisation (CAL) and thus enhance the precision of localisation, saving a lot of time and greatly accelerating machining cycles while reducing machining cost.In this paper, a method is proposed for a localisation problem that consists of rough surface matching and accuracy surface matching. Rough matching determines the variable range of the follow-up algorithms. Accuracy matching acquires the optimal location. Then fast localisation and a clamp can be implemented. A hybrid global optimisation method is adopted to cope with the accuracy matching. It shares the advantages of both genetic algorithms (GAs) and simplex algorithms. The method presented in this paper has been used in the 5-axis machining of both large Kaplan and Francis hydro turbine blades. It shows that the method is easy to realise and the algorithm is steady and robust. 相似文献
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Analysis of profile measurement techniques employed to surfaces planed by an active machining system 总被引:1,自引:0,他引:1
The importance of a reliable and robust surface profile measurement system in the inspection of surface finish is beyond any doubt. For years, visual inspection has been employed in industries to determine the quality of surface finish. Since, in most cases, it fails to ensure a consistent minimum standard of finish quality, mechanical stylus based measurement systems have successfully taken over from human inspection. However, in recent years, the trend is to explore other techniques for conducting surface profile measurements. Non-contact optical methods have emerged as one of the leading candidates. In this paper, capabilities of two optical profile measurement methods (namely, light-sectioning and two-image photometric stereo) have been explored for surfaces machined using an active machining system. These profile measurement results have been compared to the ones obtained from a conventional mechanical stylus instrument. An industry-standard Talysurf CLI system has been used to provide the benchmark, traceable to NPL standards, for the measurements. Suitability of different measurement techniques have been discussed based on the results obtained. 相似文献
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非均匀有理B样条曲面五轴加工数控指令的构建与处理 总被引:1,自引:0,他引:1
为了将非均匀有理B样条曲面的几何信息和工艺信息完整地传输到计算机数字控制系统中,提出了一种新的非均匀有理B样条曲面,直接插补G指令与加工信息的传输和处理机制.解决了传统的非均匀有理B样条曲面加工方法中将曲面离散成曲线时,丢失待加工曲面与刀具接触点的法向信息和刀具轨迹切向信息的问题,有助于在计算机数字控制中实现在线三维刀具补偿和智能控制.仿真结果证实了这种方法的有效性和准确性. 相似文献
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金刚石飞切加工微结构表面的工艺参数优化 总被引:1,自引:0,他引:1
为了获得具有纳米级表面质量的微结构表面,利用‘Nanosys-300'超精密复合加工系统实现了微结构表面的三维金刚石飞切加工,研究了主轴转速、进给量以及背吃刀量对微结构表面粗糙度的影响.理论分析表明,金刚石飞切加工微结构时理论表面粗糙度沿法线方向并没有变化,而沿进给方向存在着周期变化.减小进给量和金刚石飞刀前端角或增大切削半径可以降低理论粗糙度值.实验分析表明,表面粗糙度值Ra随进给量的增加而增加,主轴转速对Ra影响不大.切削聚碳酸酯(PC)时,在5~40 μm Ra随背吃刀量的增加而增加;而切削铝合金(LY12)时,在2~10 μm Ra随背吃刀量的增加而减小.实验中Ra最好可达38 nm(LY12)和43 nm(PC).最后,利用优化工艺参数加工出了微沟槽阵列和微金字塔矩阵微结构. 相似文献
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This paper presents an any-degrees-of-freedom (anyDOF) registration method for the characterization of freeform surfaces. The method attempts to fill the research gap regarding traditional surface registration methods which are normally dedicated to solving the global optimization problem with all DOF but they lack flexibility. The proposed anyDOF method is capable of registering surfaces with any specified combination of DOF. This is particularly useful when some of the DOF are known to be unchanged according to the a priori knowledge. The anyDOF surface registration method is regarded as a typical optimization problem of finding the minimum distance from target surface to the reference surface, with constraints of the unwanted DOF. The problem is solved by the Levenberg-Marquardt method. Simulated experiments for a two-dimensional (2D) profile and a three-dimensional (3D) surface were undertaken, together with three measurement experiments including a fluid-jet polished surface, a bonnet polished surface and a diamond machined freeform surface. Experimental results show that the anyDOF registration method is highly flexible in the characterization of freeform surfaces. 相似文献
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The importance of the plasticity index for defining the degree of elastic and plastic deformation of surface asperities is described. Some experimental validation of the argument is provided and the method is extended to cover the case of ellipsoidal asperity contacts and the effect of work-hardening for a general asperity height probability distribution. It is also shown how the model may be applied to study the behaviour of multi-phase composites. The arguments are based on Hertzian contacts without tractions but may be used with reasonable confidence for contacts where the coefficient of friction is less than 0.1. 相似文献
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Xiangsong Fu Yanan Liu Chuanzhen Huang Peng Yao 《Machining Science and Technology》2013,17(6):951-970
AbstractIn this study, the cutting edge passivation by a micro-abrasive blasting method for cermet inserts and its machining performance were investigated. The micro-abrasive blasting parameters for cermet inserts were optimized and the micro-creation of cutting edge was determined with detail. A Back Propagation (BP) neural network prediction model was further established based on our micro-abrasive blasting experiment datum, which can directly evaluate the micro-abrasive blasting ability to generate the specific edge radius. The improvement of cutting performance of micro-abrasive blasted cermet inserts benefits from the strengthening of cutting edge that caused by the obvious elimination of a large number of micro-defects rooted around the edge, and the formation of circular cutting edge is the result of brittle removal and plastic removal. The micro-creation of inserts can acquire a circular cutting edge, and the optimal edge radius is 15?μm under the selected cutting conditions when the tool life was chosen as an optimization target and the surface roughness was simultaneously taken into account. It is found that the blasted cermet inserts can prolong the tool life by at least 86% and the machined-surface quality can be improved by up to 1.65?μm, compared to inserts without micro-abrasive blasting. 相似文献
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A. V. Kolubaev S. Yu. Tarasov O. V. Sizova E. A. Kolubaev Yu. F. Ivanov 《Journal of Friction and Wear》2007,28(6):514-520
The methods of speckle-interferometry, electron, optic, and atom-force microscopy were used to study the structure and regularities of deformation of surface layers on metals and alloys in friction. The causes of deformation localization are analyzed. An explanation of the strong wear resistance of Hadfield steel is proposed using data on the evolution of the surface layer structure. 相似文献