静叶片内背弧型面线切割电极丝温度场分布规律研究

基于静叶片型面的线切割加工,根据Fourier热传导理论和叠加原理,将电极丝温度场分布进行合理的简化,可得电极丝温度场分布变化,结合实际静叶片线切割后型腔表面粗糙度、电极丝损耗、切割速度等工艺指标进行分析,修正相关加工参数。试验结果表明:通过模拟电极丝温度场分布情况,对电加工参数进行调整,能有效降低电极丝损耗。     

线切割加工中材料性能对加工质量的影响

分析和研究了线切割加工中材料性能对加工质量、加工工艺以及加工效果的影响,通过不同加工材料的实验数据对比分析指出了切割加工中合理选取极性效应、放电间隙的重要性,提出了合理制定加工工艺、实施加工方法以及优化加工参数的一些具体措施和解决对策。实践证明完善了切割工艺,提高了加工质量。     

Effect of coupling between melt shape and temperature field on electromagnetic shaping

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｃａｓｔｉｎｇｔｅｃｈｎｉｑｕｅｗａｓａｐ ｐｌｉｅｄｔｏｏｂｔａｉｎｉｎｇａｌｕｍｉｎｕｍｉｎｇｏｔｓｗｉｔｈｌａｒｇｅｃｒｏｓｓ ｓｅｃｔｉｏｎｉｎ 1980 ,ｉｎｗｈｉｃｈｌｏｗｅｌｅｃｔｒｉｃｃｕｒｒｅｎｔｆｒｅ ｑｕｅｎｃｙｗａｓｕｓｕａｌｌｙｓｅｌｅｃｔｅｄ[1～ 5] .Ｉｎｏｕｒｌａｂｏｒａｔｏｒｙ ,ｔｈｅｒｅｓｅａｒｃｈｉｓｆｏｃｕｓｅｄｏｎｔｈｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｓｈａｐｉｎｇｏｆｂｌａｄｅ ｌｉｋｅａｎｄｔｈｉｎ ｐ…     

Integrated model for assessment of electromagnetic force field due to arc welding

Abstract

Computation of the electromagnetic force over a wide range of consumable arc welding parameters is difficult with available models because of the need for experimentally evaluated electrode extension for every individual set of parameters. This becomes more complicated in case of submerged are welding, because the welding arc remains buried beneath flux. This study presents a new approach of integrating mechanistic model of electrode extension with the computational model of electromagnetic force, wherein the apparent electrode extension is obtained by solving the electrode melting rate equation. The proposed approach is demonstrated through a case on submerged arc welding. The effect of current, voltage, electrode diameter, contact tip to workpiece distance and polarity, on the electromagnetic force, is determined and analysed. This investigation shows that detrimental effects of welding electromagnetic force can be restricted without compromising productivity because after initial rapid increase, no considerable change in melting rate is caused by the force under consideration.     

电火花线切割机的抗电磁干扰设计

从电磁干扰信号的产生、耦合的途径出发，介绍了数控电火花线切割机抗电磁干扰设计的几种常用的思想和方法。     

电磁铆接电磁场数值模拟

为了分析电磁铆接电磁场的变化规律,采用数值模拟方法,以ANSYS软件为平台建立了电压激励的电磁场耦合模型.通过电阻分流器测最线圈放电电流,验证建立耦合模型的正确性.研究结果表明:驱动片主要受轴向磁场力作用,沿驱动片径向分布不均匀,在驱动片半径一半附近轴向磁场力最大;磁场力沿驱动片厚度方向呈梯度分布.在线圈与驱动片之间,磁场主要沿径向分布,渗入驱动片的磁场呈衰减分布.     

冷凝器炉中钎焊温度场三维有限元分析

文中对SF-X05平行流式汽车空调冷凝器在钎焊炉中的传热行为进行了分析.通过定义工件表面不同区域的辐射率、对流换热系数来表征不同区域受到的热流密度的差异关系,从而优化了冷凝器三维数值模拟的算法.同时,分析了冷凝器炉中钎焊的温度场,对比实测与模拟结果,试验结果表明了所开发的有限元模拟程序的准确性,从而为后续的工艺改进提供一个有效的理论分析手段,达到节省试验成本的目的.     

金属熔焊成形三维温度场数值模拟与分析

针对三维金属熔焊技术经历多次重叠热循环,层间等待时间直接影响成形质量和焊缝微观组织及可能引起的成形缺陷,建立了基于Sysweld求解器的单道多层直线往返堆积路径有限元模型,并进行加工试验验证. 结果表明,数值模拟技术可准确得到金属熔焊复杂的温度场及循环曲线,随层数的增加,热量累积,热源后方热影响区不断扩大,需设置层间等待时间保证成形质量. 等待时间大于30 s时,焊缝区经历明显的温度循环,成形质量较好. 等待时间越长,焊缝微观组织晶粒越均匀细密.     

非均匀磁场作用下磁流变弹性体悬臂夹层梁振动响应实验分析

流体压力脉动致振是影响大型服务器液冷系统管道可靠性的重要因素之一。基于ANSYS workbench中的模块连接功能,提出一种液冷管道振动应力分析方法。首先在Static Structural模块中分析管道在稳定流体压力作用下的应力情况,然后在Harmonic Response模块中分析管道在流体压力脉动作用下的响应情况。测量实际管道的振动加速度,并结合有限元仿真计算结果进行对比分析,确定液冷管道中流体的压力脉动幅值。分析结果表明：弯管处是管道上应力最大的部位,应优先进行振动可靠性分析。该成果可为大型服务器液冷系统管道可靠性研究提供了一种可行的振动分析方法。     

Refinement and migrating behaviors in Al-Si hypereutectic alloys solidified under electromagnetic vibration

The effects of electromagnetic vibration (EMV) on the refinement and migration of primary silicons in the Al-18 wt pct Si alloy were investigated systematically. It was found that EMV could effectively refine primary silicons. The equivalent diameter of primary silicon first decreases slowly with the current increasing from 1 A to 3 A, but then drops rapidly between 3 A and 10 A, next gradually decreases with increasing current intensity. When the EMV intensity was low, the primary silicons were agglomerate...     

面向对象技术在线切割加工图形软件中的应用

采用面向对象技术和Visual C^ 6．0工具对线切割加工图形软件进行了开发，描述了面向对象技术中的封装性、继承性、多态性在电火花线切割加工软件开发过程中的具体应用。     

Influence of electromagnetic brake on flow field of liquid steel in the slab continuous casting mold

Metallurgical effect of electromagnetic brake (EMBR) could be influenced by many factors. A three-dimensional finite-volume mathematical model of region electromagnetic brake process has been built based on the theory of computational fluid dynamics (CFD) and magneto-hydrodynamics (MHD). Three-dimensional numerical simulation is studied by using the commercial software. The results from numerical simulation show that flow field in the mold can be effectively controlled by electromagnetic brake; electromagnetic force is the motive power of braking, the effects of EMBR is associated directly with the intensity magnitude of magnetic field, the reciprocal position between magnetic field and acting region and casting speed, etc.     

数控电火花线切割加工在塑料模加工中的应用

分析了数控电火花线切割加工在塑料模加工中的应用场合,探讨了数控电火花线切割加工在塑料模加工应用中的几种特殊方法.     

高速精密冲床动态不平衡力优化分析与振动特性研究

高速精密冲床运转工作时,内部机构质量产生的惯性力作用在机架上,会造成机体的不平衡,引发冲床产生振动,在机械加工时易降低零件的精度和缩短冲床的使用寿命.对高速精密冲床的动态不平衡力和振动模态进行了分析,得出了减小动态不平衡力质量块的最佳质量和平衡效果,从结构改善方面提出了减小振动的方案.首先对某型高速曲柄式精密冲床进行惯性力模型推导,以了解此冲床工作过程的受力,然后利用滑块的配重和杆件质心位置等参数做惯性力分析及比较,最后利用推导出的惯性力作为数值分析计算法的边界条件,在有限元软件ANSYS中分析结构的振动特性,找出部分结构的改良方案,为以后冲床的设计方案提供理论依据.     

Investigation on the displacement fluctuation of the linear motor feed system considering the linear encoder vibration

Optical linear encoder is generally adopted to realize the full-closed loop control for the linear motor feed system. Its reading head installed on the worktable may vibrate as a result of the excitation of disturbance harmonics, which leads to the encoder's error. This study aims to investigate the mechanism of displacement fluctuation due to the encoder's error caused by the worktable vibration in the linear motor feed system. The vibrating modes of feed system are analyzed firstly, and then the influences of three torsional vibrations on encoder's errors are investigated. The transfer function between disturbance and output response is proposed to analyze the influence of encoder's error on the displacement fluctuation. The relationships among vibration, encoder's error, thrust harmonic and displacement fluctuation are discussed in detail. The results show that the encoder's error can produce obvious displacement fluctuation for the linear motor feed system, which is actually an electromechanical coupling process due to the direct drive and full-closed loop control. Finally, three effective measures are put forward to diminish the system displacement fluctuation.     

An analysis and optimisation of the geometrical inaccuracy due to wire lag phenomenon in WEDM

An extensive study of the wire lag phenomenon in Wire-cut Electrical Discharge Machining (WEDM) has been carried out and the trend of variation of the geometrical inaccuracy caused due to wire lag with various machine control parameters has been established in this paper. In an extremely complicated machining process like Wire-cut EDM, which is governed by as many as ten control factors, it is very difficult to select the best parametric combination for a particular situation arising out of customer requirements. In the present research study, all the machine control parameters are considered simultaneously for the machining operation which comprised a rough cut followed by a trim cut. The objective of the study has been to carry out an experimental investigation based on the Taguchi method involving thirteen control factors with three levels for an orthogonal array L₂₇ (3¹³). The main influencing factors are determined for given machining criteria, such as: average cutting speed, surface finish characteristic and geometrical inaccuracy caused due to wire lag. Also, the optimum parametric settings for different machining situations have been found out and reported in the paper.     

电子束焊接过程温度应力场三维有限元仿真

利用MSC．MARC有限元分析软件，在考虑电子束焊接匙孔效应基础上，采用双椭圆热模型，通过增大热传导系数、降低弹性模量和屈服强度的方法来模拟焊接过程中流体的流动效应，并采用自编子程序模拟了热源移动的过程，给出了铝锂合金电子束焊接过程中的温度应力场分布。计算结果表明：铝锂合金电子束焊接时，电子束热源对焊缝热冲击较大，焊缝附近处最高温度可达1300℃左右，三维方向上存在巨大温度梯度，成为热应力集中产生的根源。同时分析了焊缝不同位置处的等效应力演化过程，发现焊缝初始端应力剧烈振荡，处于复杂的三维应力状态，且自始至终高于焊缝的其他位置处的应力分布，成为接头区域薄弱环节。     

Refinement and migrating behaviors in A1-Si hypereu- tectic alloys solidified under electromagnetic vibration

The effects of electromagnetic vibration (EMV) on the refinement and migration of primary silicons in the Al-18 wt pct Si alloy were investigated systematically...     

Mastercam和Twincad在线切割加工方面的应用

以某级进模一块凹模板的低速走丝线切割加工为例,较为详细地讲述了运用Twincad 和Mastercam软件的低速走丝线切割加工的工艺、步骤及软件的具体运用.     

电火花线切割自动编程系统零件特征模型的研究

根据电火花线切割自动编程系统对零件智能化，参数化设计以及零件的三维显示和加工过程仿真的需要，通过对电火花线切割加工对象的分析，结合OpenGL在图形几何建模上的特点，建立了零件的特征模型，并在Winodws98下使用Visual C^ 开发了自动编程系统的仿真系统。