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61.
A 2D Finite Element Model set up using the Arbitrary Lagrangian Eulerian (A.L.E) formulation proposed in Abaqus/Explicit (v6.4) is employed to predict serrated chip formation during cutting process. No artificial criterion is employed to create the chip or to initiate serrated chip formation. The sensitivity of serrated chip prediction to numerical and process parameters is analyzed in this paper. Experimental tests in orthogonal cutting conditions on machining of AISI-4140 with coated and uncoated cemented-carbide inserts were carried out to validate numerical results. They showed significant influence of cutting speed and rake angle on the serrated chip phenomena. The comparison between numerical and experimental results showed a good qualitative agreement and underlined the outstanding influence of the element dimensions employed in Finite Element Modeling (F.E.M.) tests. 相似文献
62.
High production machining and grinding is becoming essential to enhance productivity and profitability. But such machining technique inherently increases the machining and grinding zone temperature, which in turn enhances tool wear rate and impairs the product quality. Historically cutting compounds and grinding fluids are applied to control such high temperature. Not only are such cutting fluids not very effective, but most importantly they are being perceived as a major source of pollution from the machining and grinding industry. The drastic cooling action of liquid nitrogen jets does provide desirable temperature control along with other technological benefits. Several research groups and a few organisations in different parts of the world are investigating the effects of cryogenic cooling on the machinability and grindability of different work materials using different approaches. 相似文献
63.
H.-Y. Xu J.-S. Dai 《The International Journal of Advanced Manufacturing Technology》2002,19(5):325-329
An approach to 3D implicit curve interpolation in computer numerical systems (CNC) is presented. A 3D implicit curve is the
intersection of two implicit surfaces. Geometric entities of 3D implicit curves are related to motion entities along the curve.
The results are then used to develop real-time 3D implicit curve interpolation. An improved interpolation scheme has been
proposed to augment the initial interpolation scheme to eliminate the cumulative point deviations. Simulations of implicit
curve interpolation have been carried out to verify the effectiveness of the proposed algorithm. They also demonstrate that
under typical machining conditions, the interpolation error for the improved scheme is well within the accuracy requirements
of typical machines. The example has an application potential for tool-path interpolation when tool paths are obtained by
intersecting an implicit design surface by drive cylinders. These show that the proposed algorithm is potentially useful for
the machining of implicit surfaces. 相似文献
64.
以实例的形式给出加工中心主轴准停装置几种常见的故障现象,并说明维修排障的具体方法,对加工中心的实际维护与维修具有指导意义. 相似文献
65.
66.
Partchapol Sartkulvanich Taylan Altan Joerg Soehner 《Machining Science and Technology》2005,9(2):271-288
To obtain reliable results from Finite Element (FE) simulation of machining processes, it is necessary to have as input the properties of the workpiece and tool materials as well as the characteristics of the tool/chip interface. These input parameters include physical and thermal data, friction and heat transfer, and most importantly the flow stress of the workpiece material under high strain, strain rate and temperature conditions that exist during the process. This paper presents a brief review of FE simulation of machining processes, a review of the approaches used to determine the flow stress at high deformation rate, and the examples of different constitutive equations used to represent such flow stress data. A material property database (MADAMS) has been developed and provides useful information to conduct simulations of machining processes. The main objectives of the material database are to assist researchers in areas of machining analysis and material modeling and to promote collaboration between various international research groups. 相似文献
67.
玻璃孔加工的试验研究 总被引:3,自引:0,他引:3
研究了电镀金刚石工具结构和加工参数对玻璃孔加工质量和加工效率的影响。试验结果表明,在电镀金刚石工具端部开槽,可获得小的玻璃爆边直径和高的材料去除率。冷却方式影响玻璃孔的加工质量,主轴转速和配重载荷影响玻璃孔的加工效率。 相似文献
68.
工程陶瓷的新加工方法 总被引:2,自引:0,他引:2
工程陶瓷材料具有耐高温、耐腐蚀、抗磨损及抗热冲击等优点。但由于硬度高、脆性大、大多数陶瓷材料不导电,传统的机械加工方法难以加工,使用范围受到限制。近年来,高压磨料水射流这种新兴的加工工程陶瓷的方法越来越受到人们重视。它具有效率高、成本低等优点,并可以加工出形状复杂的产品。 相似文献
69.
Efficiency Measures of Process Plans for Machined Parts 总被引:1,自引:2,他引:1
G.A. Britton G. Thimm S.C. Fork F. Jiang 《The International Journal of Advanced Manufacturing Technology》2001,17(11):819-824
This paper presents an overview of the authors’ rooted tree technique for process planning. The overview provides the foundation
for the main part of the paper, which explains how the rooted tree can be used to develop efficiency measures of process plans.
The efficiency measures are determined by comparing an actual tree and its subgraphs with an "ideal" tree. The "ideal tree"
is one that minimises the number of manufacturing operations. The paper proves that the "ideal tree" is a directed design
dimension graph plus one operation. Three measures of efficiency are presented: finishing efficiency, preforming efficiency,
and overall efficiency. The practical value of the efficiency measures is demonstrated by presenting measures of plans for
four industrial parts. It is also argued that the efficiency measures provide a quantitative assessment of process plans that
can be used to improve them and manufacturing technology. 相似文献
70.
Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro-machining to micro- and nano-machining of simple-to-complex shapes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations, and many more. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade in order to build a relatively new route of laser-hybrid processes. This paper reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The article also highlights the research gaps and future research directions in the context of laser and laser-hybrid ablation. 相似文献