简易大尺寸座标测量系统

本文介绍大型产品中的大尺寸工件位置偏差的简易测量方法、测量原理、偏差计算的程序、系统测量误差的分析.适合于小批量、低精度工件现场检测.     

异形工件专用荧光磁粉探伤机的研制使用

众所周知，磁粉探伤作为铁磁性材料表面缺陷最有力的检测手段在检测工作中得到了十分广泛的应用。在锅炉、压力容器、压力管道及石化管件及一些大型构件的局部检测中一般采用磁轭法或旋转磁场法探伤，但对一些形状复杂或工件有一定批量的情况这种方法就显得效率不高和灵敏度不够，存在局部漏检现象。在无损检测工作中，经常会遇到一些特殊工件的无损探伤难以有效进行。比如对石化管件（如三通、四通等）、     

大型工件井式热处理炉控制系统研制

针对大型工件井式热处理炉的工艺和控制要求,系统采用工控机配套组态软件作为上位主控设备,可编程逻辑控制器、PID调节器、智能电力监测仪、变频器、数字功率调节器、数字阀门控制器等组成下位设备,构成一种典型的中型DCS集散控制系统。该系统采用双机冗余技术,在满足热处理过程的工艺参数检测与全过程优化控制的同时,提高了大型工件热处理监控系统的可靠性和稳定性。     

数字化检测技术在模具修复中的研究与应用

随着模具在制造业应用领域的发展,模具修复工作也显得极为重要.首先简要介绍了数字化检测技术的重要思想,进而详细阐述了数字化检测技术在模具修复中的检测方法和检测步骤,最后利用一实例验证了数字化检测技术在模具应用中的可行性.     

电力系统下的综合数字化自动化技术创新平台分析

随着我国社会迅速发展,社会对于电力资源需求日渐增加,促使我国电力系统日益完善,并且引入了诸多先进技术手段。综合数字化自动化技术创新平台当前已经成为我国电力系统改革创新的强大支撑,并且积极应用到了电力系统的建设当中,有效地提升了电力系统的自动化水平。本文将针对电力系统综合数字化自动化平台的组成进行详细分析,探究电力系统综合数字化自动化平台的设计策略,明确电力系统综合数字化自动化平台的应用优势。     

振动时效技术在大型曲轴加工中的应用

介绍了振动时效技术在大型曲轴加工过程中的应用,试验结果表明:经振动时效处理后的工件再经磨削工序,加工应力释放得非常平稳,工件变形明显减小。影响曲轴加工中由应力导致变形的因素是多方面的,振动时效消除加工应力在某种程度上需通过各项工艺参数之间的合理选配。     

压力对等离子氮化工艺的温度均匀性影响

等离子氮化不用辅助加热，阴极工件各区域的温度取决于工件能量的热平衡，取决于离子和中性粒子的轰击，同时温度通过热传导、对流和辐射而损失。本文着重分析压力和阴阳极距离对流密度和温度均匀性的影响，叙述大型曲轴的等离子氮化，具有应用推广价值。     

四猫爪大型汽缸垂弧及挠度的控制方法

分析了大型汽缸在加工过程中控制垂弧及挠度,以减少汽缸在安装、运行时的变形,提高运行品质,提高安全可靠性,分析了产生的原因,给出了控制方法,第一次在大型工件加工的方法中提出按挠性件加工的思想,对大型工件的加工具有普遍的指导意义。     

大型轴类工件喷气冷却流动和传热特性的数值模拟

以某喷气冷却装置为参考,对缝隙喷气冷却大型轴类工件展开研究.通过数值模拟研究了具有两相对缝隙的大型轴类工件(直径D=1 000～3 000 mm)喷气冷却装置内的漉动传热特性,对比数值计算结果与实验数据验证了模型预测的准确性,探讨了大型喷气冷却装置内部气体的流动特点,分析了双缝隙喷气冷却轴类工件的传热规律,获得了轴类工...     

数字化测量技术在转轮叶片修复中的应用

本文介绍了空间中曲面工件的数字化测量方法。通过运用激光跟踪仪、转站等技术对水轮机转轮叶片进行测量,方便修复与加工工作。旨在提高叶片等曲面工件修复效率和修复质量。     

利用数控机床工作台的回转中心设置工件零点的技巧

工件零点是工件坐标系的原点,在数控镗铣加工中心上,一次装夹需要设置多个工件零点。利用工作台的回转中心可以同时设置多个工件零点,既准确方便,又节省辅助加工时间。     

Heat transfer analysis of intermittent grinding processes

An analytical solution for a two-dimensional boundary-value problem that models the transfer of heat to the workpiece during an intermittent grinding process has been previously constructed. In this solution, two variable functions in the boundary condition of the problem described the interrelation between the grinding wheel, the workpiece and the grinding fluid. In this paper, a numerical algorithm is developed. This algorithm allows one to study the effect on the workpiece temperature of varying either the velocity of the workpiece and/or the cycle-times related parameters. Our objective is to determine the values of the appropriate parameters so that the amount of material removed is maximized and the amount of coolant required is minimized.     

一台组合机床双夹紧压力液压系统的设计

一台微型汽车后桥组合机床 ,在加工时因夹紧力过大而导致工件变形。笔者通过对变形原因的分析 ,提出了有效的改进途径 ,设计了双夹紧压力液压系统来解决工件变形问题     

An analytical model for transient temperature distributions in coated carbide cutting tools

The cutting temperature during metal cutting processes has been recognized as one of major factors influencing the tool performance and workpiece geometry accuracy.     

消除剩磁对焊接电弧的影响

焊接电弧的稳定与否直接影响焊接质量的好坏 ,磁场对焊接电弧的影响是其中不忽视的一种作用。本文重点介绍了焊接质量在生产过程中遇到并解决的几种工件剩磁磁场对焊接电弧的不良影响及解决办法     

Three-dimensional modeling of heat transfer and fluid flow in laminar-plasma material re-melting processing

Modeling study is performed concerning the heat transfer and fluid flow for a laminar argon plasma jet impinging normally upon a flat workpiece exposed to the ambient air. The diffusion of the air into the plasma jet is handled by using the combined-diffusion-coefficient approach. The heat flux density and jet shear stress distributions at the workpiece surface obtained from the plasma jet modeling are then used to study the re-melting process of a carbon steel workpiece. Besides the heat conduction within the workpiece, the effects of the plasma-jet inlet parameters (temperature and velocity), workpiece moving speed, Marangoni convection, natural convection etc. on the re-melting process are considered. The modeling results demonstrate that the shapes and sizes of the molten pool in the workpiece are influenced appreciably by the plasma-jet inlet parameters, workpiece moving speed and Marangoni convection. The jet shear stress manifests its effect at higher plasma-jet inlet velocities, while the natural convection effect can be ignored. The modeling results of the molten pool sizes agree reasonably with available experimental data.     

某1000 MW超超临界汽轮机铸造汽缸加工技术研究

分析了某1000MW超超临界汽轮机超高压、高压、中压外缸结构,技术要求,加工难点.针对工件重、尺寸大、刚性差、异形、精度高、密封要求严等特点,拟定了能有效保证加工精度、高效率、低成本的加工方案,技术先进,经济效益显著.     

Experimental study of distribution of energy during EDM process for utilization in thermal models

Electrical discharge machining (EDM) has steadily gained importance over the years because of its ability to cut and shape a wide variety of materials and complicated shapes with high accuracy. The effectiveness of the EDM process is evaluated in terms of the material removal rate, relative wear ratio and the surface roughness of the work piece. The input discharge energy during this process is distributed to various components of the process, which further influences the material removal rate and other machining characteristics like surface roughness. Since during this process the electrical energy is converted into heat energy, hence the theoretical modeling of this process is based upon the heat transfer equations and in all existing thermal models the fraction of the energy transferred to the workpiece, is one of the important parameters. The accurate prediction of the fraction of energy effectively transferred to the workpiece will help to reduce the errors of the thermal models. In this study experiments have been performed to study the percentage fraction of energy transferred to the workpiece utilizing heat transfer equations, at different EDM parameters. This study also relates the optimum parameters with the optimum utilization of input discharge energy and hence will help to improve the technological performance of this process.     

Thermal conduction induced by electron-beam

The electron-energy deposition profile within the workpiece, induced by a perpendicularly impinging electron-beam, is obtained by solving the electron-beam transport equation via a Monte Carlo approach. The profile serves as the external electron generation in the two-temperature model. The beam is assumed to be a continuous source (not pulsed), and the energy exchange between the electron-beam and the target workpiece occurs at a time scale much shorter than the characteristic time of thermal conduction by electrons and phonons inside the workpiece. A series of numerical results explain the details of the heating phenomena at the nanoscale using an electron-beam.     

Experimental and numerical studies of AISI1020 steel in grind-hardening

Currently, most of the researches studying grind-hardening have used Design of Experiments approach to obtain empirical correlations without any in-depth theoretical analyzes. In this paper, a comprehensive numerical model is developed to simulate the temporal and spatial temperature distributions of the workpiece under the dry grind-hardening condition using finite element method. The simulated hardness penetration depth is deduced from the local temperature distribution and time history of workpiece and its martensitic phase transformation conditions. The results from simulations are validated with experiments. The effect of two major grinding parameters, workpiece speed and depth of cut, on the hardness penetration depth are discussed.