基于流场分析的螺旋电极电解加工孔的研究

发布时间：2018-04-27 21:18

本文选题：电解加工 + 流场分析　；参考：《西华大学》2015年硕士论文

【摘要】：孔的加工一直以来是制造业的加工难点。传统的机械加工小孔包含钻孔、冲孔和磨孔等,但是传统加工在一些硬度较高的材料,如硬质合金,磨具刚等方面显得十分乏力,不仅是加工效率低下,在加工质量上也很难保证。电解加工是上个世纪出现的新的加工技术,是21世纪加工孔的重要技术之一。电解加工的本质上是颗粒腐蚀的过程,从理论上说能加工任何导电的材料,同时由于以离子的形式去除材料,因此能够保证加工质量和加工精度。对于电解加工,国内外都做了很多的研究,其研究领域也不同,有的是加工电压的大小,有的是电解液的浓度等等,而从鲜有从加工间隙内电解液流场的角度为出发点研究电解颗粒的流向及运动情况。本文模拟分析过程为,首先建立电解加工的理论模型,然后将模型导入ICEM中划分网格及边界条件设置(这里只是名称设置,后续参数在CFD前处理中进行),再将画好的网格导入CFX中设置具体参数并且运行,运行结果在CFD-POST中处理,本文主要做了如下工作。分析了圆柱电极在不同转动的情况下的侧面流场和底部的流场情况。通过对圆柱电极的模拟,分析了圆柱电极的底部和侧面颗粒的运动情况,结果表明,电极转动会使得电解颗粒向加工间隙内流动,如果转速越高颗粒流动的速度会越快,但是也发现如果转速过高,会使得颗粒碰撞电极,且使颗粒堆积在底部从而影响加工效率。因此,只有在特定的转速情况下才能够最大的发挥电解加工效率。分析了螺旋电极在不同的转速下的流场分析。通过仿真实验得到螺旋电极确实使得加工效率增加,原因是螺旋电极的特殊外形,使得电解加工过程中流场分布发生了改变,与此同时在Z向上产生了一个速度,从而加速了电解颗粒的运动,使颗粒能够更好的逃离加工间隙。本文以颗粒为研究对象,分别分析了颗粒的压强梯度和流量,从理论上讲如果值越大将会越有利于电解加工。分析得到转速越高压强梯度和流量都会增加,但是同圆柱电极相同,转速过高都会使得颗粒碰撞电解使得颗粒难以逃逸出去,且堆积在底部,因此影响加工效率。因此,螺旋电极提高了电解加工的效率,但只有特定的转速才能够有利于电解加工。虽然通过分析得到了螺旋电极有利于电解加工,但是对于螺旋电极的参数还未讨论,最后通过在特定的转速条件下对螺旋电电极的四参数(螺距、底槽宽、槽深和螺旋角)进行正交实验。通过三水平四因素正交实验建立9组不同的电极,通过对压强梯度和流量分析,得到:对于压强分析,螺距和槽深越小,底槽越宽越压强梯度越大,对于流量得到,螺距越小底槽越宽流量越大。从物理角度上分析得到,流量和压强梯度越大将会带走更多的电解颗粒,越有利于电解加工。因此,合适的减小螺距和适当的增加底槽宽度将会有利于电解颗粒逃逸加工间隙,有利于提高电解加工效率。
[Abstract]:Hole processing has always been a manufacturing difficulty. The traditional machining holes include drilling holes, punching holes and grinding holes, but the traditional machining is very weak in some high hardness materials, such as cemented carbide, grinding tools and so on, not only is the processing efficiency low, Processing quality is also difficult to guarantee. Electrolytic Machining (ECM) is a new machining technology in the last century and one of the most important techniques in the 21 ~ (st) century. Electrolytic machining (ECM) is essentially a process of particle corrosion. In theory, it can process any conductive material, at the same time, it can ensure the quality and precision of machining because of removing the material in the form of ions. For electrolytic machining, many researches have been done at home and abroad, and the research fields are also different. Some of them are the size of the processing voltage, some are the concentration of electrolyte, and so on. The flow direction and movement of electrolytic particles are studied from the point of view of electrolyte flow field in machining gap. The process of simulation and analysis in this paper is as follows: first, the theoretical model of ECM is established, and then the model is imported into ICEM to divide the grid and set the boundary conditions (in this case, it is just the name setting, The following parameters are processed in CFD pre-processing, and then the drawn grid is imported into CFX to set specific parameters and run. The running results are processed in CFD-POST. The main work of this paper is as follows. The lateral flow field and the flow field at the bottom of the cylinder electrode under different rotation conditions are analyzed. Through the simulation of the cylindrical electrode, the movement of the bottom and side particles of the cylindrical electrode is analyzed. The results show that the electrode rotation will make the electrolytic particles flow into the machining gap, and the higher the rotational speed, the faster the particle flow will be. However, it is also found that if the rotational speed is too high, particles will collide with the electrode, and the particles will pile up at the bottom, which will affect the processing efficiency. Therefore, only in the specific speed of the case can maximize the efficiency of ECM. The flow field analysis of helical electrode at different rotational speeds was carried out. The simulation results show that the spiral electrode does increase the machining efficiency because of the special shape of the spiral electrode, which makes the flow field distribution change during ECM, and at the same time produces a speed in Z upward. Thus, the movement of electrolytic particles is accelerated and the particles can escape the machining gap better. In this paper, the pressure gradient and flow rate of particles are analyzed respectively. In theory, the larger the value is, the more favorable ECM will be. The analysis shows that the higher the rotational speed the higher the pressure gradient and the flow rate will increase but the higher the rotational speed will make the particle collision electrolysis make it difficult for particles to escape and pile up at the bottom so the processing efficiency will be affected. Therefore, the helical electrode improves the efficiency of ECM, but only the specific rotational speed can be beneficial to ECM. Although it is found that helical electrode is beneficial to ECM, the parameters of helical electrode have not been discussed. Finally, the four parameters (pitch, bottom slot width) of helical electrode are obtained under specific rotating speed. The groove depth and spiral angle were tested by orthogonal test. Nine groups of different electrodes were established by orthogonal experiment of three water and four factors. Through the analysis of pressure gradient and flow rate, it was obtained that for pressure analysis, the smaller the pitch and groove depth, the wider the bottom slot, the greater the pressure gradient, and for the flow rate, the greater the pressure gradient. The smaller the pitch, the wider the flow rate. From the physical point of view, the larger the flow rate and pressure gradient, the more electrolytic particles will be taken away, which is more favorable to ECM. Therefore, a proper reduction of pitch and a proper increase of the width of bottom slot will be conducive to the escape gap of electrolytic particles and to improve the efficiency of ECM.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG662

【参考文献】