高速加工切削热产生机理及监控技术研究综述

在概括总结了高速加工主要特点的基础上,分析了高速加工切削热产生机理及目前的研究状况,构建了基于光学、软测量技术和网络通信的计算机刀具综合监控系统,重点从高速加工切削温度场建模和数字仿真、切削温度测量和实时监控等方面论述了切削热产生机理及监控技术的研究思路,最后指出了高速切削刀具种类和刀具参数的选择方法,以及高速切削虚拟仿真软件研制等方面存在的技术难点,这些工作为高速加工应用的基础理论研究提供了技术支撑.     

有限元仿真技术在金属切削加工中的应用进展

得益于计算机和有限元技术的迅速发展,有限元仿真技术已经成为研究切削加工工艺及机理的重要手段。介绍了金属切削加工有限元仿真模型,从高速切削、刀具表面微织构、微切削,以及切削参数与刀具几何优化等方面论述了有限元仿真技术在金属切削加工中的应用进展,并展望了未来的发展方向。     

高速切削技术在难加工材料上的应用

通过对金属传统切削机理与高速切削机理的比较，从切屑成形原理、切削热的产生分布及传递、刀具磨损、表面质量、生产率的提高等各方面来阐述高速切削技术在难切削材料中的应用。     

高速切削温度的二维热传导模型建立及求解

在高速加工过程中,切削热的产生将影响工件加工表面的质量和刀具寿命,分析切削温度的分布对研究切削机理及工艺参数的优化有着重要意义。基于传热学和金属切削理论建立了高速车削温度的热传导模型,结合切削过程中的边界条件和初始条件,应用数学解析法推导出二维热传导方程的解,利用求解导热逆问题的方法估算边界条件。实验中采用人工热电偶测量切削温度,根据测得的刀具内部点的温度值计算出表面热流,进而通过MATLAB软件仿真得到切削温度场,并利用红外热像仪的测量结果进行试验验证。     

高硬度合金高速加工刀具温度场的研究进展

高硬度合金高速加工时,切削区域因剧烈摩擦产生的切削热是影响刀具磨损的重要因素。本文围绕前刀面温度场和内部温度场两个方面,总结近年来刀具温度场的研究进展。从已有研究来看,对刀具前刀面温度场的研究主要在于热源和热分配比的确定,刀具内部的热传导过程主要为非傅里叶热传导模型的建立。本文系统梳理了刀具前刀面温度场模型、测量技术和刀具内部热传导模型的理论和方法,分析了当前研究存在的不足,并对未来高速加工刀具温度场的研究方向进行了展望。     

数控高速加工技术研究

高速切削技术是机械制造业发展的必然趋势,其应用将大幅度地提高加工效率和加工质量。高速切削技术不仅涉及到高速切削加工工艺及高速切削机理,而且包括高速切削所用的刀具、机床等诸多因素。本文着重介绍了高速切削各相关技术的研究动态,并对高速切削技术的应用前景进行了展望。     

高速切削加工刀具技术研究

对高速加工刀具系统进行了深入研究，分析了传统刀具系统存在的弊端，提出了高速切削加工对刀具系统的要求。从刀具材料技术、刀具－机床接口技术、刀具平衡技术、刀具平衡技术、刀具结构设计技术等方面论述了适宜高速切削加工的刀具技术方法，并对未来高速加工刀具系统发展趋势进行了探讨。     

高速加工原理及刀夹、刀具选用

高速切削加工能够大大提高切削速度 ,提高工件的加工质量和刀具的耐用度。在高速切削条件下 ,材料的切削机理将发生变化 ,切削过程将变得容易 ,切削热将降低。介绍了正在研究和应用的刀夹类型和刀具材料。     

高速切削加工工具技术研究

研究高速加工刀具系统,分析传统刀具系统存在的弊端,提出高速切削加工对刀具系统的要求,从刀具材料技术、 刀具-机床接口技术、刀具平衡技术、刀具结构设计技术等方面论述了适宜高速切削加工的刀具技术方法,并探讨对未 来高速加工刀具系统发展趋势。     

高速加工原理及刀夹,刀具选用

高速切削加工能够大大提高切削速度,提高工件的加工质量和刀具的耐用度。在高速切削条件下,材料的切削机理将发生变化,切削过程将变得容易,切削热将降低。介绍了正在研究和的刀夹类型和刀具材料。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.