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  本文選題：螺旋線　切入點：螺旋角　出處：《西安工業(yè)大學》2015年碩士論文　論文類型：學位論文

【摘要】：在等螺距螺旋線電解加工中傳統(tǒng)陰極的工作齒與陰極體是一體的,沿用傳統(tǒng)陰極加工變螺距螺旋線,線槽必然被加寬,造成陽線“塌壁”,特別是從0°起變的大螺旋角變螺距螺旋線幾乎不能加工,這是因為剛性工作齒不能按螺旋線方程改變角度。本文提出一種新的分立式陰極,沿陰極的軸向并垂直于軸將工作齒切成若干某種厚度的片,每片均含陰極體整圈的工作齒,稱為輪盤。當陰極按螺旋線方程運動時,受內(nèi)嵌于陰極體的微電機驅(qū)動的每個輪盤各自按加工的螺旋線位置取向,實現(xiàn)工作齒的包絡(luò)線與被加工螺旋線螺旋角方向一致。但是工作齒相鄰齒節(jié)間臺階臨近流場易出現(xiàn)空穴、分離、渦流等缺陷,影響成型精度。為解決得到均勻的流場,本文提出了圓弧等齒厚工作齒和圓弧變齒厚工作齒兩種齒牙形狀的分立式陰極設(shè)計,先后采用八種修形方案,基于COMSOL Multiphysics模擬各方案工作齒與被加工工件之間的加工間隙流場分布,比較各方案的流線場、流速場以及壓力場,結(jié)合時均阻力系數(shù)的計算結(jié)果進行分析,結(jié)果表明,方案八中將每片厚輪齒一側(cè)切去一半,同時將旋出的臺階全部倒成0.3mm的圓角,并將薄齒的另一側(cè)旋出臺階的右下角全部倒成0.4 mm的圓角,流場效果顯著改善。這種根據(jù)工作齒錯位形成的位置設(shè)計的圓弧變齒厚工作齒,有效地降低了輪盤旋轉(zhuǎn)形成工作齒節(jié)間的臺階對流場的影響。為進一步對齒牙形狀優(yōu)化,基于脊狀表面減阻機理,在上述最佳方案的基礎(chǔ)上,設(shè)計了側(cè)表面具有不同尺寸分布的脊狀結(jié)構(gòu)的工作齒,利用COMSOL Multiphysics對工作齒與被加工工件之間的加工間隙流場進行分析,研究脊狀結(jié)構(gòu)的形狀參數(shù)與電解液流速、湍流參數(shù)和剪切速率之間的關(guān)系,結(jié)果證明,工作齒表面脊狀尺寸為s=0.2mm、h=0.05mm的脊狀結(jié)構(gòu)不僅可以減小摩擦阻力,而且有效地穩(wěn)定了間隙流場。
[Abstract]:The working teeth of the traditional cathode and the cathode body are integrated in the equal pitch helix ECM. If the traditional cathode is used to process the variable pitch helix, the slot will be widened. This causes the "wall collapse" of the positive line, especially the helical spiral line with large helical angle from 0 擄, which can hardly be machined, because the rigid working teeth can not change the angle according to the helix equation. A new discrete cathode is proposed in this paper. Along the axis of the cathode and perpendicular to the axis, the working teeth are cut into a number of plates of some thickness, each of which contains the working teeth of the cathode body in a whole circle, called a wheel. When the cathode moves according to the helix equation, Each wheel driven by a micromotor embedded in the cathode is oriented separately according to the helical position of the machining, The envelope of the working tooth is consistent with the spiral angle of the spiral line being machined. However, the defects such as cavity, separation, eddy current and so on are easy to appear near the flow field between the adjacent teeth of the working tooth. In order to solve the problem of obtaining a uniform flow field, the forming accuracy is affected by the defects such as cavity, separation, eddy current and so on. In this paper, a discrete cathode design for the shape of two kinds of tooth teeth with circular arc equal thickness working teeth and circular arc variable tooth thickness working teeth is presented. Eight modification schemes have been adopted one after another. Based on COMSOL Multiphysics, the flow field distribution between the working teeth and the machined workpiece is simulated, the streamline field, velocity field and pressure field of each scheme are compared, and the calculated results of the average resistance coefficient are analyzed. In the eighth scheme, each thick gear tooth is cut off in half, at the same time, the spinning steps are all turned into a round angle of 0.3 mm, and the other side of the thin tooth is rotated out of the lower right corner of the step into a 0.4 mm corner. The effect of flow field is greatly improved. The circular arc variable tooth thickness working tooth is designed according to the position of the working tooth dislocation, which effectively reduces the influence of rotating disk on the step flow field between the working teeth. In order to further optimize the tooth shape, Based on the drag reduction mechanism of the ridge surface, the working teeth with different size distribution on the side surface are designed on the basis of the above optimum scheme. The flow field between the working teeth and the machined workpiece is analyzed by COMSOL Multiphysics. The relationship between the shape parameters of the ridge structure and the electrolyte flow rate, turbulence parameter and shear rate is studied. The results show that the ridge structure with a ridge size of 0.2 mm / h on the surface of the working tooth can not only reduce the friction resistance, but also reduce the friction resistance. Moreover, the gap flow field is effectively stabilized.
【學位授予單位】：西安工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG662

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本文編號：1595966