双层摆梁的剪板机

法国普洛梅坎(Promecan)公司生产了一种新型的机械传动剪板机(图1)。其主要技术规格:被剪板厚×被剪板宽为4×3100毫米(剪切中碳钢或不锈钢板时为2.5×3100毫米),每分钟行程次数为90。当被剪板宽大于2米时,后挡料架的挡料长度为750毫米,而被剪板宽等于或小于2米时则剪切长度不受限制。机器的主要特点有:(1)采用双层摆梁结构,外梁作为压料梁,内梁作为刀架。内梁支承在外梁两侧臂上,由于内梁和外梁的摆动轴线离下刀刃的距离成一定的比例,因此在剪切过程中压料力始终与剪切力成一定的比例;     

五坐标水切割中的刀具补偿方法

针对五轴水切割自动编程和加工问题,提出五轴水切割的刀具补偿方法.采用五坐标刀具长度补偿法控制五轴水切割靶距;刀具长度补偿值适应喷嘴长度调整.通过分析三维刀具半径补偿与刀位轨迹计算的一致性,利用刀具半径补偿法初步规划五坐标水切割刀位轨迹曲线.应用结果表明,刀具补偿法对解决五轴水切割加工靶距控制是切实可行的,且解决了水切割编程工具的问题.     

基于PLC的水下切割装置速度控制系统研制

水下切割装置在进行切割作业时,在水面不能直接获知其运行状态。原有系统用液压马达的流量对水下切割装置的运行速度进行估计,误差较大,响应速度慢。为解决速度检测精度等问题,对原有系统进行改造,采用深水码盘实现切割速度检测,使用比例流量阀调整液压马达流量,实现转速的实时精确控制。基于可编程逻辑控制器实现了水下切割装置的速度控制。     

高速走丝线切割锥度加工时的切点补偿

分析了高速走丝线切割机进行锥度切割时的切点补偿问题，给出了误差产生的原因及补偿原理、补偿值计算、补偿方向和补偿过程。     

剪板机剪切力与剪板断面形貌的关系浅析

通过观察剪板机剪板的断面形貌,分析剪板机的剪板过程,进而导出了一种剪切力的简易计算方法,该法计算结果与常用公式的计算结果近似,但方法更为简单,可作为设计计算的参考。     

凸轮在数控剪板机刀片间隙调整机构中的应用

介绍了数控剪板机刀片间隙自动调整机构中两种不同电位器反馈刀片间隙值的方式。实践证明：凸轮和直线电位器并用的结构，能真实反馈刀片间隙，准确控制间隙精度，从而可靠地保证了剪板质量。     

一种新型铸坯定重切割技术

在连铸-棒材生产流程中,开发了新型铸坯定重切割技术,满足高效率、低成本连铸连轧的生产需要。采用静态辊道秤采集铸坯重量信息,高精度红外摄像系统控制铸坯切割长度,利用PLC、WinCC等软件处理铸坯重量、长度信息与生产工艺参数间的逻辑、数学关系,实现了铸坯定重切割的自动运行。技术实施后,铸坯定尺误差在1015 mm,铸坯单重合格率稳定在70%左右,棒材工序成材率提高0.15%。     

气焊及切割工艺与设备

激光切割中的超声速喷嘴辅助气体流场分析与结构改进 激光切割过程的实现是高能激光束与辅助气体相互作用的结果，喷嘴内部形状及其产生的流场特征是影响激光切割质量和效率的关键因素之一。根据可压缩流体轴对称N-S方程，采用结构网格和二阶精度的有限体积法，分析激光切割的超声速喷嘴辅助气体射流场结构与喷嘴喉部转角的关系，以及研究发散段长度对流场状态参数的影响规律，通过合理规划喉部转角与发散段长度，     

WEDM角形精度与AGIEpilot

ＷＥＤＭ角形精度与ＡＧＩＥｐｉｌｏｔ北京市电加工研究所，瑞士机械服务有限公司杨建国，张雄伟线切割放电加工（ＷＥＤＭ）工件的几何精度，除计量线性长度误差外，还应检验角部形状精度（角部精度人角部精度泛指切割方向改变时所产生的形状误差。显然，角形精度应包括...     

氧生物柴油火焰温度计算及火焰切割分析

从理论上分析生物柴油用于金属火焰切割的可行性,根据热力学理论计算生物柴油中性焰和氧化焰的理论温度,分析生物柴油燃烧过程中氧气的消耗量;并根据燃烧学对比分析生物柴油与汽油在空气中完全燃烧的火焰长度。计算结果表明:虽然生物柴油火焰温度比乙炔燃烧温度低,但能达到2436℃以上,火焰长度将近是汽油火焰长度的0.92倍,长度基本相当,说明生物柴油可用于金属火焰切割,只是预热时间应比乙炔长。这在理论上说明生物柴油可作为金属切割的燃料,为进一步进行氧生物柴油火焰切割技术研究奠定了理论基础。     

Phase field methods and dislocations

We present a general formalism for incorporating dislocations in Phase Field methods (PFM) based on the elastic equivalence between a dislocation loop and a platelet inclusion of specific stress-free strain. Dislocations may be elastically and dynamically coupled to any other field such as a concentration field. Special attention is paid to the treatment of dislocation cores after the discretization of real and reciprocal space required by the computer implementation of any PFM. In particular, we propose a method based on two length scales to account for dislocation cores much smaller than the grid spacing. The method is illustrated through the simulation of the motion of a dislocation loop in a microstructure representative of a late-stage γ/γ′ microstructure.     

Fast real-time NURBS path interpolation for CNC machine tools

In this paper, a novel fast real-time non-uniform rational B-spline (NURBS) path interpolation method is presented. This method efficiently integrates the data processing of a NURBS path in a CNC controller, from pre-processing to real-time interpolation. In the calculation of the total length of the NURBS path, the numerical adaptive quadrature method adapts to the integrand, i.e. the first derivative of the length function, automatically, dividing the parameter interval into subintervals with fine or coarse spacing according to the varying condition of the integrand. This new method takes full advantage of the subdivision scheme. The key point is to generate inverse length functions (ILF) for each resulting subinterval. In the real-time NURBS path interpolation, the new setting path parameter can be calculated directly using the ILF without the need for any time-consuming computation of NURBS derivatives and iteration. The proposed method is extremely fast, accurate and suitable for real-time implementation, and simulations and practical tests proved its effectiveness.     

Physical modeling of metalworking processes—I: Determination of large plastic strains

This article discusses the application of the visioplasticity method to the evaluation of large plastic strains such as those occurring in metalforming. Although this method can be used for any mode of deformation, its application to plane-strain deformation is treated here. The distortion of a quadrilateral element of a grid is tracked to compute strains during deformation. In each case any two lines of the quadrilateral can be used (length before and after deformation and direction cosines before deformation) to determine strains in the element. The method has been verified by application to basic cases of deformation such as uniaxial compression, tension, pure shear, and rotation of elements. The effect of choice of lines upon the results of strain calculation is also discussed.     

Calibration of a hexapod machine tool using a redundant leg

Parallel configurations are recently being applied to the machine tool with the hopes of greater rigidity, stability, and accuracy than conventional multi-axis structures allow. However, the many calibration methods presently available for serial machine tools are not applicable to hexapod type structures. A calibration method is presented that uses a ball–bar or other simple length measuring device to act as an ‘extra leg,’ allowing calibration of the hexapod's true kinematic parameters. This method utilizes a total least squares minimization, does not require any special hexapod configuration or difficult six degree of freedom pose measurements, and is effective with as few as one additional length sensor. Selection of calibration pose sets is briefly discussed, as well as the influence of measurement noise on calibration accuracy. Simulations show the potential for this algorithm to significantly reduce errors to the point where machining errors are within 5–10 times the measurement errors.     

平衡气量控制法合成四针状氧化锌晶须的形貌和发光性能

以金属锌为原料不添加任何催化剂,在700°C时通过平衡气量控制法合成四针状氧化锌晶须。研究了成长时间对样品微结构和发光性能的影响。结果表明,制备的样品是由四针状氧化锌组成的;四针状氧化锌针的长度和直径随成长时间的延长而增加;在样品的室温发光谱中,在385~391nm处出现强的紫外光发射,但没有任何深水平发射,且紫外发射的强度随样品成长时间的延长而增强。     

Development of an automatic arc welding system using a sliding mode control

This paper describes the development of an automatic welding control system for alternating current shield metal arc welding. This method could replace manual operations which require a well-trained technician. We have derived a mathematical model of the welding control system and identified system parameters. An adaptive sliding mode controller, estimates the bound of uncertainties, and modulates the rate of the electrode feed mechanism that regulates the arc current. The electrode feed-rate mechanism with this controller is driven by an AC servomotor, which can compensate for both the molten part of the electrode and undesirable fluctuations in the arc length during the welding process. The method can be easily applied to any welding system in which the electrode is consumed during the welding process. By maintaining the magnitude of the arc current at the desired value and the stability of the arc length, excellent welding performance is obtained. The simulation and the experimental results both show that this automatic welding control system, based on the adaptive sliding mode controller, can perform effectively.     

工业结构钢疲劳极限的断裂力学研究

文章提出一种预测材料疲劳极限的简便方法。该方法仅需获得一个材料参数(如材料硬度)便可确定材料的裂纹扩展抵抗阻力曲线。由于有效应力强度因子范围门槛值ΔKeffth∞是一个与裂纹长度及应力比无关的材料常数,只需将裂纹张开应力强度因子门槛值Kopth表示为裂纹长度的函数,作出材料的疲劳断裂曲线,就可以预测任意应力比下光滑试样的疲劳极限。利用这种方法作出的预测值与试验结果一致。     

Geometric model of robotic arc welding for automatic programming

0　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｒｅｅｋｉｎｄｓｏｆｉｎｆｏｒｍａｔｉｏｎａｒｅｎｅｅｄｅｄｆｏｒａｕｔｏｍａｔｉｃｐｒｏｇｒａｍｍｉｎｇｏｆａｒｃｗｅｌｄｉｎｇｒｏｂｏｔ.(1)Ｇｅｏｍｅｔｒｉｃｉｎｆｏｒｍａｔｉｏｎｏｆｗｅｌｄｉｎｇｗｏｒｋｐｉｅｃｅ,ｉｎｃｌｕｄｉｎｇｇｅｏｍｅｔｒｉｃｉｎｆｏｒｍａｔｉｏｎｏｆｗｅｌｄｉｎｇｓｅａｍｆｏｒｗｅｌｄｉｎｇｐａｔｈｐｒｏｇｒａｍｍｉｎｇ,ｇｒｏｏｖｅｓｈａｐｅａｎｄｓｉｚｅｆｏｒｗｅｌｄｉｎｇｐａｒａｍｅｔｅｒｓｐｒｏｇｒａｍｍｉｎｇａｎｄｗｏｒｋ…     

用于自动编程的机器人弧焊几何模型

几何信息对于弧焊机器人自动编程具有重要作用,本文建立了完整的机器人弧焊几何模型,在焊缝曲线几何模型中,提出用焊缝长度为参数建立参数方程表达任意形状的焊缝,并给出了确定焊缝上离散编程点的方法,在焊接工件几何模型中,针对焊接结构的特点,采用三级基本体系和基本体素对表示焊接工件,给出了具体的数据结构。在焊枪位姿变换中,定义了世界坐标系,焊枪坐标系和活动坐标系给出了坐标系间的变换关系,在此几何模型基础上,     

细长轴加工夹具的应用

介绍在车床上加工细长轴专用夹具的设计制造过程。使用该夹具可切削加工任意长度的细长轴。