关于逆向车削加工细长轴误差的力学分析

针对细长轴车削加工，分别在两种不同装夹条件下(一端卡盘夹紧、一端顶尖支承和两端顶尖支承)进行正向切削和逆向切削时的工件变形进行了力学分析，建立了正逆向切削工件在切削力作用下产生弯曲变形的解析模型。具体算例表明：逆向切削时工件的弯曲变形以及由此引起的加工误差远小于同等条件下正向切削的变形和误差。该模型及分析结果可用于细长轴加工的工艺设计。     

恢复加工中心在线检测功能的实践

介绍了恢复Mandelli加工中心在线检测功能所做的工作.分析了影响壳体零件加工质量的因素,并探索出实现加工过程在线检测功能与作用的有效途径.     

Finite element modeling of residual stresses in machining induced by cutting using a tool with finite edge radius

A thermal elastic-viscoplastic finite element model is used to evaluate the residual stresses remaining in a machined component. An improvement in the accuracy of the predicted residual stresses is obtained by: (a) using a modified Johnson–Cook material model that is augmented by a linearly elastic component to describe the material behavior as non-Newtonian fluid; (b) using a remeshing scheme to simulate the material flow in the vicinity of the rounded cutting tool edge without the use of a separation criterion; (c) properly accounting for the unloading path, and (d) considering the thermomechanical coupling effect on deformation. Case studies are performed to study the influence of sequential cuts, cutting conditions, etc., on the residual stresses induced by orthogonal machining.     

加工中心立柱可适应动态优化设计

应用定量化的分析工具,对加工中心立柱结构进行了可适应动态设计过程分析。提出产品可适应性的综合评价指标,建立了产品可适应性综合评价模型。应用多级模糊综合评价方法在对产品功能适应性等多种评价指标进行初级评价的基础上,进行了二级综合评价,得到了VMC850加工中心立柱产品可适应性综合评价等级,从而为进一步改进产品设计提供了指导和修改依据。在方案设计阶段,通过给出各方案的可适应性度量数值以及对修改设计的难易程度做出定量评价,可有效地指导机床结构设计过程。     

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通过长期拉伸试验研究,发现软件系统自动给出的R_eL、R_eH、R_p0.2、A_gt值不一定准确,应根据拉伸曲线对试验结果进行验证,如果发现问题应进行修正;还应对试验机设置的试验速度是否满足GB/T 228.1—2010中应变速率控制要求进行验证;试样的加工精度不满足标准要求时,应采取相应的解决措施。     

Surface integrity in electro-discharge machining, ultrasonic machining, and diamond saw cutting of ceramic composites

Good surface integrity is frequently required for structural ceramic components, since the lifetime of a ceramic component is in most cases determined by its surface features. In this study, the surface integrity of electro-discharge machined, ultrasonic machined, and diamond saw cut ceramic composites has been investigated and compared. The surface roughness, hardness, and topography of the machined surface were examined. Flexural strength and its distributions were used to evaluate the effect of machining process on the surface integrity of the machined specimens. Results show that the machining process had an important effect on the surface quality of the machined ceramics. Electro-discharge machining of ceramics created a heat-affected surface layer with poor surface integrity, such as cracks and craters, and the variable surface damages on the electro-discharge machined specimens resulted in low Weibull modulus. Within most machining conditions, the ultrasonic machined and diamond saw cut specimens behaved fairly consistently, and the flexural strength and Weibull modulus were higher than that of the electro-discharge machined specimens.     

工程陶瓷加工技术的现状与发展

综述了工程陶瓷的传统加工方法,特种加工方法以及对未来新技术的展望,分析得出工程陶瓷加工技术发展的必然趋势是多种加工技术相复合的加工技术。     

加工中心故障分析及其可靠性增长的措施

从加工中心的故障诊断分析着手,根据加工中心工作和功能特点,研究其故障模式和原因,提出排除故障的方法,最终提高机床的可靠性,为实施可靠性增长技术提供相应的支撑,有助于提升数控机床行业的核心竞争力。     

Virtual process systems for part machining operations

This paper presents an overview of recent developments in simulating machining and grinding processes along the NC tool path in virtual environments. The evaluations of cutter–part-geometry intersection algorithms are reviewed, and are used to predict cutting forces, torque, power, and the possibility of having chatter and other machining process states along the tool path. The trajectory generation of CNC systems is included in predicting the effective feeds. The NC program is automatically optimized by respecting the physical limits of the machine tool and cutting operation. Samples of industrial turning, milling and grinding applications are presented. The paper concludes with the present and future challenges to achieving a more accurate and efficient virtual machining process simulation and optimization system.     

掘进机摇臂升降负载敏感控制系统设计与研究

针对掘进机液压系统定量泵供油、换向阀中位机能卸荷,系统耗能多、换向主阀阀芯设计复杂等问题,设计掘进机摇臂升降负载敏感系统。在验证负载敏感变量泵模型、换向阀HCD模型、掘进机摇臂平面机构模型基础上,搭建掘进机摇臂升降负载敏感控制系统仿真模型,分析掘进机摇臂升降系统中位卸荷性能,研究了平衡阀先导比、摇臂液压缸尺寸、液压缸大腔回油主阀阀芯节流面积对摇臂升降性能的影响。结果表明：换向阀处于中位,系统中位卸荷阀开启,泵处于低压卸荷工况;增大摇臂液压缸缸径、平衡阀先导比、B口SymbolnB@T口回油背压,摇臂下降启动冲击均增大;平衡阀先导比取1.0、摇臂液压缸缸径取160 mm、B口→T口回油节流面积取24.68 mm2时,摇臂下降起动冲击较小。